Processes and systems for subtractive and additive manufacturing of patterned foils

Abstract

Provided herein are tools and methods for continuously patterning an electrically- conducting foil using a roll-to-roll electroetching and / or electrodeposition system that includes a circumferentially closed band mask exhibiting an array of holes arranged in a perforation pattern or a pattern of through-holes.

Description

[0001] PROCESSES AND SYSTEMS FOR SUBTRACTIVE AND ADDITIVE

[0002] MANUFACTURING OF PATTERNED FOILS

[0003] FIELD AND BACKGROUND OF THE INVENTION

[0004] The present invention, in some embodiments thereof, relates to manufacturing of patterned metal or metal-containing foils, and more particularly, but not exclusively, to metal foils patterned (e.g., perforated) by a seamless repeating pattern.

[0005] Patterned metal foils are widely employed in various industrial applications, such as, but not limited to, printed circuit boards and batteries, as well as for decorative purposes.

[0006] When relating to perforated patterns, thin metal foils that are perforated by a pattern of very fine holes can be used in a variety of applications, such as the aerospace industry for weight reduction and noise reduction, in the energy storage and conversion industry for energy storage and / or generation devices’ elements, in sensing and biosensing applications, and in the filtration industry for filtering very fine particles. Additionally, they can be used in the medical industry for implantable devices and in the electronics industry for shielding and heat dissipation.

[0007] In some applications, the pattern of a metal foil is required to be accurate and precise over a relatively large area of the foil in order to provide similar conditions over that area. Exemplary application which requires such precision and accuracy is the use of a perforated and or three-dimensional metal foil as a current collector in a rechargeable battery electrode.

[0008] For example, a current collector may contain a substrate layer and a patterned coating required for a particular assembly of the battery active material upon the current collector. The patterned metal layer upon the current collector may further increase surface roughness, thereby enhancing adhesion of the battery active materials to the CCs and increasing the contact area with the active material layer. The patterned surface of the current collector may further increase stability of the electrode during charge and / or discharge cycles. Perforation patterning of a current collector foil may reduce the weight of a current collector and facilitate ion transport between the two sides of the current collector to enable balanced cycling and enhance power density.

[0009] In some industrial fields, such as the battery electrode industry, the production of electrodes is executed using a very long metal foil typically provided in the form of a roll of hundreds and sometimes thousands of meters long. In such applications, the uniformity of the foil is imperative for repeatability and optimal performance of the resulting electrodes. When the foil is perforated / patterned, this uniformity requirement applies also to the perforation or its surface and / or bulk structural elements, meaning the patterned foil should exhibit a repeating pattern with no irregularities.

[0010] While a "perforation die" which has rows of needles that puncture the metal sheet through a punch press, fails to provide fine perforation (limited to holes of more than 100 pm) at high precision (limited to the span of the die) and high density of the holes, other methods, such as laser perforation and electron beam emission, can produce perforated metal foils with high precision to some extent (typically limited to about 30 % variance in holes size). Similar to other energy beam methodologies, the laser process can produce intricate geometries with exacting dimensions by burning small holes consistently and accurately, leaving a reinforced ring around each cut; however, one major drawback of energy beam perforation, e.g., laser perforation, is the high cost and time consumption, particularly when the need is to produce hundreds and thousands of meters of perforated metal foil. Other methods for producing thin metal foils with a fine perforation pattern, which are based on semiconductor lithographic techniques, suffer from one or more of the abovementioned disadvantages, and are further limited in their capacity to perforate thin foils below 100 pm in thickness.

[0011] Perforated foils may be optionally prepared through an electroetching process. Electroetching (also termed herein “electrochemical etching”) through a mask is a common method used to create precise patterns or designs in metal foils, often used in the production of filters, screens, and decorative items. The process involves placing a mask (a template stencil) on at least one face of a prefabricated metal foil and applying electric current using electrodes while the stencil covers the areas that should not be etched. The electrical current causes the metal foil to corrode and etch away, physically subtracting metal atoms from the foil and more likely forming through-holes or perforations in the material.

[0012] A mask for metal electroetching can be made of a variety of materials, such as photoresist, rubber, or metal. The etching is affected in the areas of the foil that are not covered by the mask, templating the pattern of the mask and resulting in a perforated pattern or design on the foil. Unlike chemical etching, electroetching allows high level of control over the size, shape and the spacing of individual through-holes in the perforation pattern, which can be controlled, inter alia, by adjusting the electrical current, the duration of the etching process, temperature, electrolyte composition, and the distance between the electrodes. Once the etching process is complete, the mask is removed and the perforated metal foil is rinsed to remove any residue. However, state-of-the-art electrochemical etching process is not configured for producing long patterned foils and / or seamless patterns in roll-to-roll foil configurations.

[0013] Thin and long metal foils may be produced industrially using electroforming methods, such as electrodeposition (also termed herein “electrolytic deposition” or “electroplating”). Electrodeposition is a process that allows producing metal foils by immersing an anode and a moving plating surface in an electrolyte containing a solution of metal ions and applying an electrical current between the anode and the plating surface so as to deposit a layer of metal on the plating surface by reducing the metal ions into zero valence metallic species.

[0014] There is a need for cost- and time-effective tools and methods for producing (a) metal foils having a seamless repeating pattern of fine pores or through-holes, and (b) patterned metal foils having a seamless repeating pattern, wherein the foils are produced over an unlimited length of the foil in a roll-to-roll configuration.

[0015] SUMMARY OF THE INVENTION

[0016] The present disclosure provides a roll-to-roll foil patterning system. The system may comprise an electropatterning unit. The system may comprise an input roll. The system may comprise an output roll configured to collect the patterned foil. The system may comprise a power supply.

[0017] The electropatterning unit may be configured to transform a starting foil into a patterned foil upon application of electric current and / or voltage. The electropatterning unit may be configured to transform a starting foil into a patterned foil upon application of electric current. The electropatterning unit may be configured to transform a starting foil into a patterned foil upon application of electric voltage. The electropatterning unit may comprise an electrode. The electropatterning unit may comprise an elastic mask. The electropatterning unit may comprise two or more shafts. The electropatterning unit may comprise a vessel for holding and / or circulating a liquid electrolyte composition. The electropatterning unit may comprise a fluid transportation unit.

[0018] The starting foil may be electrically conducting. The patterned foil may be electrically conducting.

[0019] The mask may have a circumferentially closed band form. The circumferentially closed band mask may have an external surface that is electrically insulating. The mask may include a contact section positioned to contact a corresponding contact section of the starting foil such that the contact section of the mask may have a curved shape, which can conform to a curvature of the contact section of the starting foil. The contact section of the mask may be positioned between the electrode and the contact section of the starting foil.

[0020] The fluid transportation unit may be configured to direct a flow of the electrolyte composition. The fluid transportation unit may be configured to direct a flow of the electrolyte composition supplied by the vessel. The fluid transportation unit may be configured to direct a flow of the electrolyte composition supplied by the vessel to be tangential to the external surface of the mask. The fluid transportation unit may be configured to direct a flow of the electrolyte composition supplied by the vessel to be tangential to the external surface of the mask along essentially an entire length of the contact portion of the mask.

[0021] The fluid transportation unit may be configured to direct a flow of the electrolyte composition supplied by the vessel to be parallel to the external surface of the mask. The fluid transportation unit may be configured to direct a flow of the electrolyte composition supplied by the vessel to be parallel to the external surface of the mask along essentially an entire length of the contact portion of the mask.

[0022] The two or more shafts may hold the mask under tension.

[0023] The fluid transportation unit may be in fluid flow connection with the vessel.

[0024] The input roll may be configured to feed the starting foil into the electropatterning unit. The output roll may be configured to collect the patterned foil.

[0025] Upon feeding the starting foil by the input roll and / or collecting the patterned foil by the output roll, the mask and the starting foil may be configured for coordinated motion while the starting foil is in contact with the mask. Upon feeding the starting foil by the input roll, the mask and the starting foil may be configured for coordinated motion while the starting foil is in contact with the mask. Upon collecting the patterned foil by the output roll, the mask and the starting foil may be configured for coordinated motion while the starting foil is in contact with the mask.

[0026] The power supply may be configured to apply voltage and / or current between the electrode and the contact section of the starting foil in the presence of the electrolyte composition. The power supply may be configured to apply current between the electrode and the contact section of the starting foil in the presence of the electrolyte composition. The power supply may be configured to apply voltage between the electrode and the contact section of the starting foil in the presence of the electrolyte composition

[0027] The electropatterning unit may comprise a washing unit. The washing unit may be connectable to a washing liquid source. The washing unit may comprise at least one nozzle facing a portion of the elastic mask. The washing unit may be configured to rinse the portion of the elastic mask with a washing liquid.

[0028] The liquid may comprise water. The washing unit may comprise two nozzles. The washing unit may be configured to wash the portion of the mask with pressurized water. The fluid transportation unit may be positioned between the electrode and the mask within the contact region. The fluid transportation unit may be positioned between the starting foil and the mask before the contact region.

[0029] The electrode may be divided into two essentially equal sections. The fluid transportation unit may be positioned between the two sections facing the mask.

[0030] The system may further comprise an ultrasonic cleaning device. The ultrasonic cleaning device may comprise an ultrasonic transducer. The ultrasonic transducer may be facing the contact section of the starting foil. The ultrasonic transducer may be configured to transmit ultrasonic waves thereto.

[0031] The system may further comprise a counter electrode. The counter electrode may be positioned adjacent to the contact section.

[0032] The system may further comprise a liquid pump. The liquid pump may be configured to circulate the electrolyte composition, in a flow path between the electrode and the counter electrode. The liquid pump may be configured to circulate the electrolyte composition, in a flow path between the electrode and the starting foil. The system may further comprise a filter. The filter may be positioned within the flow path. The filter may be configured to filter solid particles from the electrolyte composition.

[0033] The mask may comprise a hydrophilic material. The mask may be composed of a polymer or a polymer-coated metal. The mask may comprise a hydrophilic polymer or a hydrophilic polymer-coated metal. The mask may comprise a polyamide film.

[0034] Upon feeding said starting foil by the input roll and / or collecting said patterned foil by the output roll, said starting foil may be pressed against said mask. Each possibility represents a separate embodiment of the invention. Upon feeding said starting foil by the input roll and collecting said patterned foil by the output roll, said starting foil may be pressed against said mask. The input roll, output roll or both may be configured to transition the starting foil in a direction from the input roll to the output roll. Each possibility represents a separate embodiment of the invention. The pressing and the transition of the starting foil may be dragging the mask. The pressing and the transition of the starting foil may be dragging the mask so that the starting foil may be configured for coordinated motion with said mask. The dragging may be affected by friction.

[0035] At least one of the input roll and output roll may be a crowned roller. Both the input roll and output roll may be a crowned roller. The crowned roller may be configured to maintain alignment of the starting role with the mask in a lateral direction perpendicular to a direction of motion of the mask and the staring foil. The lateral direction may be substantially parallel to the surfaces of the mask and the staring foil.

[0036] The electrode may have a curved active surface having a curvature. The curvature may conform to a curvature of the contact section of the starting foil.

[0037] The electropatterning unit may comprise an element having a curved surface. The element may be configured to contact the starting foil on a first side of the contact section of the starting foil. The contact section of the mask may be configured to contact the starting foil on a second side of the contact section of the starting foil.

[0038] The mask may be configured to move towards the element prior to effecting an electropatterning process. The mask may be configured to move towards the element prior to effecting an electropatterning process, thereby forming an electropatterning zone between the contact section of the starting foil and the electrode. The surface may form a part of a lateral surface of a rotatable cylinder or of a surface of an endless belt conveyor.

[0039] The electrode may be a cathode. The curved surface may be electrically insulating. The starting foil may be connected to a positive pole of the power supply via an electrically conducting shaft. The electrically conducting shaft may be positioned outside the electropatterning zone.

[0040] The electrode may be an anode. The curved surface may be electrically insulating. The starting foil may be connected to a negative pole of the power supply via an electrically conducting shaft. The electrically conducting shaft may be positioned outside the electropatterning zone.

[0041] The mask may be configured to move towards the starting foil. The mask may be configured to move towards the starting foil thereby forming an electropatterning zone between the contact section of the starting foil and the electrode.

[0042] The mask may encircle the electrode.

[0043] The system may further comprise a computerized control unit.

[0044] The mask may be elastic and tensioned between two or more shafts.

[0045] The system may be a roll-to-roll foil electroetching system. The electropatterning unit may be a an electroetching unit. The electroetching unit may be configured to transform the starting foil into an electroetched foil upon the application of electric current and / or voltage. The electroetching unit may be configured to transform the starting foil into an electroetched foil upon the application of electric current. The electroetching unit may be configured to transform the starting foil into an electroetched foil upon the application of electric voltage. The electrode may be a cathode.

[0046] The electroetching unit may be configured to transform an electrically conducting foil into an electroetched foil through an electroetching process. The electroetching process may impart a pattern to the foil.

[0047] The mask may be an SRP-template mask. The mask may exhibit a seamless repeating patten (SRP) of through-holes. The through-holes may have an opening dimension of about 10-2,000 pm. The through-holes may have a pitch of about 50-2,500 pm, including each value and sub-range within the specified range.

[0048] The mask may have a thickness ranging from about 5 pm to about 100 pm, including each value and sub-range within the specified range. The foil may be selected from an aluminum foil and a copper foil. The foil may be an aluminum foil.

[0049] The mask may be configured to move towards said element prior to effecting an electroetching process, thereby forming an electroetching zone between the contact section of the starting foil and the cathode.

[0050] The curved surface may be electrically conductive, and the starting foil may be connected to a negative pole of the power supply via said curved surface.

[0051] The system may be a roll-to-roll foil electrodeposition system. The electropatterning unit may be an electrodeposition unit. The electrodeposition unit may be configured to transform the starting metal foil into a foil patterned by electrochemically deposited metal upon the application of electric current and / or voltage. The electrodeposition unit may be configured to transform the starting metal foil into a foil patterned by electrochemically deposited metal upon the application of electric current. The electrodeposition unit may be configured to transform the starting metal foil into a foil patterned by electrochemically deposited metal upon the application of electric voltage. The electrode may be an anode. The mask may be an SRP-template mask. The mask may exhibit a seamless repeating patten (SRP) of through-holes. The through-holes may have an opening dimension of about 10-2,000 pm, including each value and sub-range within the specified range. A horizontal distance between the centers of two adjacent through-holes may range about 50 - 2,500 pm, including each value and sub-range within the specified range.

[0052] The mask may have a thickness ranging from about 20 pm to about 300 pm, including each value and sub-range within the specified range.

[0053] The mask may be configured to move towards said element prior to effecting an electrodeposition process, thereby forming an electrodeposition zone between the contact section of the starting foil and the anode.

[0054] The curved surface may be electrically conductive, and the starting foil may be connected to a negative pole of the power supply via said curved surface.

[0055] The present disclosure further provides an electroetching process for imparting a pattern to a starting metal foil.

[0056] The process may include feeding the foil into an electroetching unit. The electroetching unit may comprise a mask and a cathode. At least a contact section of said foil may be disposed within the electroetching unit. The process may include contacting a contact section of the mask with the contact section of the foil. The contacting may form a contact region. The contact section of the mask may be positioned between the cathode and the contact section of the foil.

[0057] The process may include directing an electrolyte liquid composition to be tangential to the external surface of the mask. The process may include directing an electrolyte liquid composition to be tangential to the external surface of the mask along essentially an entire length of the contact section of the mask.

[0058] The process may include applying current, voltage or both between the cathode and the foil. Each possibility represents a separate embodiment of the invention. The process may include applying current, voltage or both between the cathode and the foil while advancing the foil through the electroetching unit. Each possibility represents a separate embodiment of the invention. The application of current, voltage or both and / or the advancing of the foil may entail electroetching the foil. Each possibility represents a separate embodiment of the invention. The electroetching the foil may entail forming an electroetched foil. The electroetching the foil may entail forming a salt of the metal.

[0059] The advancing may be coordinated with a motion of the mask.

[0060] The process may include collecting the electroetched foil.

[0061] The mask may have a form of a circumferentially closed band. The mask may have an electrically insulating external surface.

[0062] The contact region may be curved.

[0063] The process may include washing the mask from the salt of the metal with a washing liquid.

[0064] The applying current and / or voltage may be affected in the presence of the electrolyte liquid composition. The electrolyte liquid composition may comprise an electrolyte. The electrolyte may be supplied to an electroetching zone formed between the cathode and the contact region.

[0065] The process may include positioning the mask between the cathode and the starting metal foil.

[0066] The process may include positioning the foil between the mask and an anode. The electrolyte may be in contact with the anode and with the cathode.

[0067] The process may include applying current, voltage or both between the cathode and the anode. The process may include reversing the polarity of the anode and the cathode. The process may include applying reverse pulse current, voltage or both between the cathode and the anode. Each possibility represents a separate embodiment of the invention. The reverse pulse current, voltage or both may at least partially remove the salt of the metal from the electroetched foil and or from the contact section of the mask.

[0068] The electrolyte liquid composition may be in the form of an aqueous solution contained in a vessel.

[0069] The process may include circulating the aqueous solution between the anode and the cathode or between the foil and the cathode.

[0070] The process may include directing the electrolyte liquid composition to be tangential to the external surface of the mask. The process may include directing the electrolyte liquid composition to be tangential to the external surface of the mask along essentially the entire length of the contact section of the mask.

[0071] The circulation may be performed under pressure. The circulation may comprise flowing the aqueous solution using a liquid pump. The circulation may comprise flowing the aqueous solution using a liquid pump in a closed path. The closed path may be in contact with any one of the anode and the foil, the cathode and the contact region. The circulation may achieve forced and / or directed flow thereto. Each possibility represents a separate embodiment of the invention.

[0072] The foil may be selected from an aluminum foil and a copper foil. The foil may be an aluminum foil.

[0073] Contacting the contact section of the mask with the contact section of the foil may entail pressing one of the mask and foil over the other at the contact section. Advancing the starting foil may entail dragging the mask at a similar rate. Advancing the starting foil may entail dragging the mask at a similar rate to form a coordinated motion of the foil and the mask.

[0074] The process may include preventing relative shift between the starting foil and the mask in a direction which is perpendicular to the advancement direction. The direction may be parallel to a surface of the starting foil.

[0075] The starting metal may have thickness in the range of 5pm to 100pm, including each value and sub-range within the specified range.

[0076] Electroetching the foil may entail forming the salt of the metal and the electroetched foil having a plurality of etched perforations. The plurality of etched perforations may have a mean diameter of no more than 100pm. plurality of etched perforations may have an open area of the plurality of perforations in the electroetched foil in at least 15% base of the total area of the electroetched foil.

[0077] The mask may be elastic.

[0078] The process may include tensioning the mask between two or more shafts.

[0079] The process may include contacting the contact section of the foil with a lateral surface of a cylinder or with a surface of an endless belt conveyer. The process may include contacting the contact section of the foil with a lateral surface of a cylinder. The process may include contacting the contact section of the foil with a surface of an endless belt conveyer.

[0080] The feeding may be affected from a feed roll. The collecting may be affected onto an output roll, or both.

[0081] The process may include rinsing the electroetched foil. The process may include prior to the collecting, rinsing the electroetched foil. The rising may be with water.

[0082] The process may include washing the mask from the salt of the metal with a washing liquid. The washing liquid may include water. The washing may be performed continuously.

[0083] The contacting may include moving the rigid circular mask towards the contact section of the starting foil.

[0084] The advancing may comprise a coordinated rotation of at least one of said two or more shafts and said rigid circular mask.

[0085] The present disclosure further provides a process comprising, feeding an electrically conducting starting foil into an electrodeposition unit; contacting a contact section of the mask with the contact section of the foil; applying current, voltage or both between the anode and the foil while advancing the foil through the electroetching unit, thereby electrodepositing a metal on the starting metal foil; and collecting a patterned foil,

[0086] The process may include directing an electrolyte liquid composition to be tangential to the external surface of the mask. Directing an electrolyte liquid composition may be tangential to the external surface of the mask along essentially an entire length of the contact section of the mask. The mask may have a form of a circumferentially closed band. The mask may have an electrically insulating external surface.

[0087] The contact region may be curved.

[0088] The electrodeposition unit may comprise a mask and an anode, such that at least a contact section of the foil may be disposed within the electroetching unit

[0089] Contacting the contact section of the mask with the contact section of the foil may form a contact region. The contact section of the mask may be positioned between the anode and the contact section of the foil.

[0090] The advancing may be coordinated with a motion of the mask.

[0091] The present disclosure further provides a metallic member. The metallic member may include a base foil and a plurality of raised textural elements on a surface of said base foil.

[0092] The plurality of raised textural elements may be arranged in a seamless repeating pattern. The metallic member may be at least 0.1 m in width. The metallic member may be at least 0.5 m in length.

[0093] The metallic member may be prepared by the process disclosed herein.

[0094] The pattern may cover a continuous area constituting 10-95 % of said surface of the base foil.

[0095] The raised textural elements may be electrically deposited on the base foil.

[0096] The raised textural elements may have a base dimension that ranges about 10-2,000 pm. A horizontal distance between the centers of two adjacent raised textural elements can be in the range of about 50-2,500 pm.

[0097] A height of the raised textural elements may be in the range of about 5-300 pm.

[0098] The seamless repeating pattern may be characterized by uniformity of at least 15 %.

[0099] The base foil may comprise a metal selected from the group consisting of copper, nickel, gold, silver, iron, tin, aluminum, palladium, and any alloys and combination thereof. Each possibility represents a separate embodiment of the invention.

[0100] The raised textural elements may comprise a metal selected from the group consisting of copper, nickel, gold, silver, iron, tin, aluminum, palladium, and any alloys and combination thereof. Each possibility represents a separate embodiment of the invention. The base foil may be 3-100 pm thick. A height of the raised textural elements may be in the range of about 1-100 |am from the top-side of the base foil.

[0101] The present disclosure further provides a roll comprising a cylindrical core and the metallic member disclosed herein wound around said core.

[0102] A width of the metallic member may be at least 0.1-5 m.

[0103] A length of the metallic member in the roll can be at least 0.5-10,000 m.

[0104] The present disclosure further provides a current collector. The current collector may comprise at least one metallic member disclosed herein.

[0105] The present disclosure further provides an electrode comprising the current collector disclosed herein.

[0106] The present disclosure further provides a battery comprising at least one electrode according to the present disclosure. The present disclosure further provides an electric device comprising at least one battery according to the present disclosure.

[0107] BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0108] Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying figures. With specific reference now to the figures in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken with the figures makes apparent to those skilled in the art how embodiments of the invention may be practiced.

[0109] In the figures:

[0110] FIGs. 1A-B present a schematic illustration of electroetching unit 10, according to some embodiments of the present invention, showing circumferentially closed band mask 11, wound and tensioned between tension shafts 12a and 12b, encircling concave cathode 13 and positioned close to cylindrical mandrel constituting anode 14 on which foil 15 is wrapped tightly over part of the convex surface of anode 14, wherein FIG. 1A shows electroetching unit 10 in the loading stage, before mask 11 is put in contact with foil 15 and before electric power is applied, and FIG. IB shows electroetching unit 10 in the electroetching stage, in which mask 11 contacts foil 15, whereas the dashed rectangle in FIG. IB marks the contact region between mask 11 and foil 15, including contact section Ila of mask 11 and contact section 15a of foil 15, and contact is made by moving tension shafts 12a and 12b towards anode 14, moving anode 14 towards tension shafts 12a and 12b, or a combination thereof, while tension shafts 12a and 12b may be put in coordinated rotary motion with anode 14, during which electrolyte is flown between cathode 13 and anode 14 (not shown) and electric power is applied to cathode 13 and anode 14 to effect electroetching of foil 15;

[0111] FIG. 1C present a schematic illustration of the electroetching unit 10 shown in FIGs 1A- B, according to some embodiments of the present invention, wherein the concave cathode 13 is a split cathode, which include cathode portion 13a and cathode portion 13b, wherein the electrolyte can flow between cathode portion 13a and cathode portion 13b and anode 14, and wherein circumferentially closed band mask 11 is wound and tensioned between three tension shafts 12a, 12b and 12b;

[0112] FIG. ID present a schematic illustration of the electroetching unit 10 shown in FIGs 1A- B, according to some embodiments of the present invention, which further comprises a washing unit that includes a wash head 16, comprising one or more nozzles directed to closed band mask 11, a washing tray 17, positioned to collect washing liquid from closed band mask 11, and a wiper 18, that can prevent washing liquid from contacting foil 15; and further comprises a roller 19, configured to stretch closed band mask 11, thereby exposing its area to the nozzle(s);

[0113] FIGs. 2A-B present a schematic illustration of electroetching unit 20, according to some embodiments of the present invention, showing circumferentially closed band mask 21, wound and tensioned between tension shafts 22a and 22b, encircling concave cathode 23 and positioned near electrically insulating cylindrical mandrel 24 on which foil 25 is wrapped tightly over part of the convex surface of mandrel 24 and electrically conducting tension shaft 26, wherein FIG. 2A shows electroetching unit 20 in the loading stage, before mask 21 is put in contact with foil 25 and before electric power is applied, and FIG. 2B shows electroetching unit 20 in the electroetching stage, in which mask 21 contacts foil 25, whereas the dashed rectangle in FIG. 2B marks a contact region between mask 21 and foil 25, including contact section 21a of mask 21 and contact section 25a of foil 25, while tension shafts 22a and 22b may be put in coordinated rotary motion with mandrel 24, and, optionally, tension cylinder or endless belt conveyer 26, during which electrolyte is flown between cathode 23 and foil 25 (not shown) and electric power is applied to cathode 23 and tension cylinder or endless belt conveyer 26, which is connected to a positive pole of a power supply (not shown), thereby holding foil 25 at a positive voltage versus cathode 23, and effecting electroetching of foil 25;

[0114] FIGs. 3A-B present a schematic illustration of electroetching unit 30, according to some embodiments of the present invention, showing circumferentially closed band mask 31, wound and tensioned between tension shafts 32a and 32b, encircling concave cathode 33 and positioned near stationary anode 34 having a curved active surface on which foil 35 is wrapped tightly over a convex surface thereof and tension cylinder or endless belt 36, wherein FIG. 3A shows electroetching unit 30 in the loading stage, before mask 31 is put in contact with foil 35 and before electric power is applied, and FIG. 3B shows electroetching unit 30 in the electroetching stage, in which tension cylinders 32a and 32b move towards anode 34 allowing contact between mask 31 and foil 35, while tension shafts 32a and 32b may be put in coordinated rotary motion with rotation shaft 36, during which electrolyte is flown between cathode 33 and stationary anode 34 and electric power is applied to cathode 33 and stationary anode 34, thereby effecting electroetching of foil 35;

[0115] FIGs. 4A-B present a schematic illustration of electroetching unit 40, according to some embodiments of the present invention, showing rigid circumferentially closed band mask 41 having a cylinder shape viewed from the top, encircling rotating cathode 43 and positioned near foil 45 that is wound over tension / rotation shafts 46a and 46b, wherein tension shaft 26a is electrically conducting, the mask, the cathode, and the contact section of the starting foil being immersed in an electrolyte solution (not shown), wherein FIG. 4A shows electroetching unit 40 in the loading stage, before mask 41 is put in contact with foil 45 and before electric power is applied, and FIG. 4B shows electroetching unit 40 in the electroetching stage, in which mask 41 contacts foil 45, wherein the contact may be affected by moving tension shafts 46a and 46b towards mask 41, moving mask 41 towards tension cylinders 46a and 46b, or a combination thereof, whereas tension shafts 46a and 46b may be put in coordinated rotary motion with mask 41, and electric power is applied to cathode 43 and tension shaft 46a, which is connected to a positive pole of a power supply (not shown), thereby holding foil 45 at a positive voltage versus cathode 43, and effecting electroetching of foil 45 while cathode 43 may be rotated to assist electrolyte solution flow between cathode 43 and foil 45. Cathode 43 has central portion 43a and curved blades 43b and 43c which are connected to central portion 43a and which outer surfaces constitute active surface of cathode 43, wherein the shape of curved blades 43b and 43c conforms to the shape of mask 41 to provide constant distance between the active surface of cathode 43 and the contact section of foil 45;

[0116] FIGs. 5A-D present a drawing of electroetching system 500 (side view in FIG. 5A, and cross-sections in FIGs. 5B-5D), according to some embodiments of the present invention, that includes an electroetching unit including circumferentially closed band mask 51, wound and tensioned between tension shafts 52a, 52b, and 53c, encircling concave cathode 53 and positioned near electrically insulating cylindrical mandrel 54 on which foil 55 is wrapped tightly over part of the convex surface of mandrel 54 and electrically conducting tension shaft 56, wherein foil 55 is fed into the electroetching unit by input (feed) roll 57a and is collected onto output roll 57b, and wherein the electrolyte is introduced into the electroetching unit via electrolyte inlet 58;

[0117] FIG. 6 is a schematic illustration of an exemplary mask, or SRP-template mask, according to embodiments of the present invention, showing a circumferentially closed band (a loop), exhibiting a seamless repeating patten, exemplified by an exemplary pattern of hexagonal holes shown in the enlarged circle;

[0118] FIG. 7 presents a schematic illustration of two tapered holes in a mask having a local thickness, showing the diameter of the hole at the outer side ( i) being smaller than the diameter of the hole at the inner side (di) of the mask;

[0119] FIG. 8 is a flowchart presenting the rudimentary steps of the process for continuous subtractive manufacturing (roll-to-roll configuration) of a very long patterned foil by electroetching a very long pristine foil through the holes of a mask having a repeating pattern of holes, so as to form a repeating pattern of through-holes in the foil;

[0120] FIG. 9 is a photograph of the exemplary mask used in this example, exhibiting an SRP of round holes of 100 pm in diameter spaced apart by 150 pm and arranged in a hexagonal packing; and

[0121] FIG. 10 is a photograph of the perforated aluminum foil resulting from the herein- provided process, exhibiting an SRP of round through-holes of 100 pm in diameter spaced apart by 150 pm;

[0122] FIGs. 11A-B present a schematic illustration of electrodeposition unit 110, according to some embodiments of the present invention, including a circumferentially closed band mask 111, wound and tensioned between tension shafts 112a and 112b, encircling concave anode 113 and positioned close to cylindrical mandrel constituting cathode 114 having a convex surface on which a starting foil 115 is wrapped, wherein FIG. 11 A shows electrodeposition unit 110 in the loading stage and FIG. 1 IB shows electrodeposition unit 110 in the electrodeposition stage;

[0123] FIGs. 12A-B present a schematic illustration of electrodeposition unit 120, according to some embodiments of the present invention, including circumferentially closed band mask 121, wound and tensioned between tension shafts 122a and 122b, encircling concave anode 123, electrically insulating cylindrical mandrel 124 having a convex surface on which starting foil 125 is wrapped, and electrically conducting tension shaft 126, wherein FIG. 12A shows electrodeposition unit 120 in the loading stage and FIG. 12B shows electrodeposition unit 120 in the electrodeposition stage;

[0124] FIGs. 13A-B present a schematic illustration of electrodeposition unit 130, according to some embodiments of the present invention, including circumferentially closed band mask 131, wound and tensioned between tension shafts 132a and 132b, encircling mask 131, concave anode 133 , stationary cathode 134 having a convex surface on which starting foil 135 is wrapped, and tension cylinder or endless belt conveyer 136, wherein FIG. 13 A shows electrodeposition unit 130 in the loading stage and FIG. 13B shows electrodeposition unit 130 in the electrodeposition stage;

[0125] FIGs. 14A-B present a schematic illustration of electrodeposition unit 140, according to some embodiments of the present invention, showing rigid circumferentially closed band mask 141 having a cylinder shape viewed from the top, rotating anode 143, and starting foil 145 that is wound over tension / rotation shafts 146a and 146b, wherein FIG. 14A shows electrodeposition unit 140 in the loading stage, and FIG. 14B shows electrodeposition unit 140 in the electrodeposition stage;

[0126] FIGs. 15A-D present a drawing of electrodeposition system 1500 (side view in FIG. 15A, and cross-sections in FIGs. 15B-45D), according to some embodiments of the present invention, that includes an electrodeposition unit including circumferentially closed band mask 151, wound and tensioned between tension shafts 152a, 152b, and 153c, encircling anode 153 and positioned near electrically insulating cylindrical mandrel 154 on which starting foil 155 is wrapped tightly over part of the convex surface of mandrel 154 and electrically conducting tension shaft 156, wherein starting foil 155 is fed into the electrodeposition unit by input (feed) roll 157a and is collected onto output roll 157b, and wherein the electrolyte is introduced into the electrodeposition unit via electrolyte inlet 158;

[0127] FIG. 16 is a flowchart presenting the rudimentary steps of the process for continuous additive manufacturing (roll-to-roll configuration) by electrodepositing metal upon a very long starting foil through the holes of a mask having a repeating pattern of holes, so as to form a seamless repeating pattern of protruding elements on the starting foil; and

[0128] FIGs. 17A-B present microscope images of an exemplary copper foil including copper textural elements electrodeposited on its surface, resulting from the herein-provided process, the elements being cone-shape textural elements of approximately 10-20 pm height and 100 pm base diameter spaced apart by about 150 pm, wherein FIG. 9A presents a top view at X20 magnification, and FIG. 9B presents a tilted side view at X50 magnification).

[0129] DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0130] The present invention, in some embodiments thereof, relates to manufacturing of patterned electrically-conducting (e.g. metal or metal-containing) foils, and more particularly, but not exclusively, to metal foils patterned by a seamless repeating pattern. Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details set forth in the following description or exemplified by the Examples. The disclosure is meant to encompass other embodiments or of being practiced or carried out in various ways.

[0131] In some aspects and embodiments, the present invention provides a system that can perform electroetching of electrically conductive (e.g., metal or metal-coated polymer) foils in a roll-to-roll configuration in order to create indents or pores within the foil or perforate the foil. In some aspects and embodiments, the present invention provides a system that can perform electrodeposition of a metal over electrically conductive starting foils, such as metal, metal-coated polymer, graphite, carbon, or conductive polymer foils, in a roll-to-roll configuration in order to create a foil having a patterned surface or bulk, e.g., having voids within the foil and / or surface elements protruding from the foil surface. In addition, the present invention provides a tool that allows forming a patterned foil having a seamless repeating pattern over extended lengths, which are restricted only by practical considerations and not by process limitations. Electroetching is a metal etching process that uses a solution of an electrolyte, an anode, and a cathode. The metal piece to be etched is connected to the positive pole of an electric power source. Another piece of metal, known as the cathode, is connected to the negative pole of the power source. To minimize unwanted effects, the anode and cathode may be made of the same metal. The electrolyte may also contain the same metal cation. When current or voltage is applied between the anode and the cathode, the metal of the anode undergoes an oxidation reaction, thereby dissolving and releasing a metal cation to the electrolyte. Simultaneously, the cation in the electrolyte undergoes a reduction reaction, thereby being converted into metal and deposited on the cathode. Other complex electrochemical effects can occur based on voltage and electrolyte concentration, but the main effects involve oxidation / dissolution at the anode and reduction / depo sition at the cathode.

[0132] In the context of the present invention, the term “electroetching” refers to a process in which an electrically conducting material, such as metal, is held at a positive potential against a counter electrode and is in ionic contact with the counter electrode, e.g., via an electrolyte, thereby undergoing oxidation, such that the material is being dissolved and ions of the material are released to the electrolyte.

[0133] While reducing the present invention to practice, the present inventors have demonstrated an electroetching system comprising a mask configured as a circumferentially closed band or loop, wherein the mask is used as a stencil for a repeating pattern, which is designed to produce a desired configuration of pores or holes within an electrically- conducting foil, including a seamless repeating pattern. Aspects of the present invention provide a roll-to-roll architecture that enables the production of a continuous porous or perforated foil with predesigned patterns. The tools and methods according to the various aspects and embodiments of the present invention provide control over the electroetching process, allowing to perforate foils of different thicknesses, such as battery grade aluminum foil, while achieving high precision (low variance) in pores area, even when having relatively small pores and / or relatively high open area of the perforations. Hence, the present invention allows the production of continuous thin metal foils suitable for industrial manufacturing processes, which may exhibit a seamless repeating pattern (SRP) of fine indents or through-hole elements, which is essentially identical over extensive lengths of the foil (such as at least 1 meter long), namely exhibiting uniformity of the fine pattern essentially along and across the entire area of the foil.

[0134] With respect to electrodeposition, the electrodeposition system according to the various aspects and embodiments of the present invention, includes a mask configured as a circumferentially closed band or loop, wherein the mask is used as a stencil for a repeating pattern, which is designed to produce a metal foil having a particular configuration of voids and / or protruding surface elements, as dictated by the mask, including a seamless repeating pattern. Aspects of the present invention provide a roll-to-roll architecture that enables the production of a continuous patterned foil with predesigned patterns. The tools and methods according to the various aspects and embodiments of the present invention provide control over the electrodeposition process, allowing to create patterned foils with different thicknesses which may be assembled in a roll, such as battery grade copper foil, while achieving high precision (low variance) in pattern shape and dimensions. Hence, the present invention allows the production of continuous thin metal foils suitable for industrial manufacturing processes, which may exhibit a seamless repeating pattern (SRP) of fine indents or protruding elements, which is essentially identical over extensive lengths of the foil (such as at least 1 meter long), namely exhibiting uniformity of the fine pattern essentially along and across the entire area of the foil. The system and process of the present invention allow manufacturing of metal foils composed of a single type of metal (e.g., when electrically depositing copper on a copper starting foil or a combination of metals (e.g., when electrically depositing copper on a nickel starting foil). In other words, the disclosed system and process may allow patterning a metal foil with a different metal, e.g., for forming functional or decorative textured coatings.

[0135] Roll-to-roll electroetching system:

[0136] As known in the art, electroetching is a process that uses an electric current to etch metal from a metal substrate surface by oxidizing the metal into metal ions. Electroetching may be used to transfer a pattern from a mask onto the metal surface. The mask is placed over the metal substrate’s surface. Electric current is passed through the electrolyte solution, and the metal is dissolved only from the surface that is not covered by the mask, thereby transferring the mask pattern to the metal surface and / or bulk (depending on the duration and conditions of the electroetching process). At certain process conditions, transferring the pattern to the metal surface results in surface alterations, while more aggressive or longer electroetching process may form holes in the metal starting foil. The mask is typically made of a material that is inert to the electrolyte solution and the general conditions of the process, including during the flow of the electric current.

[0137] In some embodiments thereof, the present invention provides an electroetching system for forming indents or through-holes in a pristine electrically-conducting foil, which is configured to produce a very long (at least 1 meter and preferably more than 100 meters) patterned foil (metallic member) in a roll-to-roll configuration. The system includes an input (feed) roll that feeds a pristine foil into an electroetching unit (EU), and an output roll for collecting the etched (patterned) foil. Indents or through-holes may be etched in the foil in a seamless repeating pattern in the electroetching unit, which includes a mask in the form of a circumferentially closed band that exhibits a pattern of holes. A section of the mask is positioned between a cathode and a section of the foil, and the foil is held at a positive voltage versus the cathode by physically contacting an anode or being in electrical contact with a positive pole of the power supply, wherein the cathode is connected to the negative pole thereof. The section of the foil that contacts the section of the mask is etched when a voltage is applied to the electrodes (namely, the cathode and the foil or the anode), wherein the electrodes are in ionic contact, e.g., by flowing an electrolyte solution therebetween. Accordingly, indents or through-holes are formed in the foil essentially in the areas that are not covered (masked) by the mask material, namely the indents or through-holes are formed in the foil according to the holes in the mask.

[0138] In the context of the present invention, the term “cathode” refers to the electrode on which a reduction reaction takes place within the electroetching unit, whereas the term “anode” refers to the electrode on which an oxidation reaction (i.e., electroetching) takes place. The cathode is therefore connected to the negative pole of the power supply, and the anode is connected to the positive pole of the power supply. Polarity of the electrodes may be reversed when the process includes applying reverse pulsed voltage and / or current for a certain period of time.

[0139] In the context of the present invention, the terms “starting foil” “pristine metal foil”, “pristine foil”, and “substrate foil” refer to a foil before undergoing an electroetching process that forms pores therein, such as indents or through-holes and / or enables electrodeposition of a metal thereon, that forms a plurality of raised textural elements. The patterned foil may be a porous foil, i.e., containing pores. In the context of the present invention, the term “pore” refers to hollow structures such as an indent, depression or recess formed within the foil not extending through the entirety of the thickness of the foil, as well as to hollow structures extending through the entirety of the foil, also termed herein “through-holes”. The through holes may be used, inter alia, to create the desired pattern within the pristine foil or cut the pristine foil into discrete pieces following electroetching and collection on the output roll.

[0140] In the context of the present invention, the terms “porous metallic foil”, “porous foil”, “patterned metallic foil”, and “patterned foil” refer to an electrically conducting foil exhibiting a pattern of pores therein, including, inter alia, through-holes. In some embodiments the pattern of pores follows a seamless repeating pattern.

[0141] In the context of the present invention, the terms “perforated metallic foil” “perforated foil” and “metallic member” refer to a metal foil exhibiting a pattern of though-holes therein. In some embodiments the pattern of through-holes follows a seamless repeating pattern.

[0142] When referring herein and throughout to a “foil” or a “metal foil”, it is meant to refer to both pristine and patterned (e.g., perforated) states of the metal foil, before it undergoes the process of electroetching, during the process and thereafter. It is noted herein that the metal foil is an electrically-conducting foil by virtue of it being made of metal, regardless of its perforation or lack thereof. The term “electrically-conducting foil”, as used herein, is meant to encompass metal and metal alloy foils, as well as foils made of composite materials or combinations of materials, wherein at least one of said materials is electrically conductive, e.g., being in a form of a metal layer disposed over an electrically insulating substrate, such as a polymer, or having metal regions dispersed throughout an electrically insulating material, wherein said metal regions are at least partially present on the surface of the foil.

[0143] The pristine foil may be solid (non-porous), porous, or perforated, even prior to the electroetching process, wherein the electroetching process enhances its porosity by creating additional pores and / or increasing the volume (e.g., depth) of the existing pores. In general, to controllably produce a precise pattern when electroetching a metal foil using a mask with holes thereon, it is necessary for the mask to be in direct contact with the foil. For a dynamic and continuous electroetching process, having the mask in a constant contact with the foil can present mechanical, electrical, and chemical challenges for the system and the process. In the context of the present invention, the contact sections of the mask and the foil are preferably in contact in order to achieve high stenciling fidelity of the pattern of holes from the mask to the foil, as defined and explained hereinbelow.

[0144] In the context of the present invention, the term “stenciling fidelity” refers to the accuracy of the pattern that is created when using a stencil, whereas the mask acts as a stencil. A high stenciling fidelity means that the pattern in the mask is reproduced in the foil with a high level of control on the accuracy and the consistency of the production and, with little or no distortion or loss of detail.

[0145] In order to provide a long and patterned foil, the foil may be constantly passed through the electroetching unit and the mask may be rotated, such that a certain section of the mask is always positioned between the cathode and a new section of the foil. The mask is stretched over the foil to eliminate contact between areas of the foil that are not configured for etching and the electrolyte. In order to afford for the constant contact between a section of the mask, the foil, and the electrolyte, advancement of the foil through the electroetching unit may be coordinated with the rotation of the mask. The flow of the electrolyte may be restricted to the contact region of the mask of the foil. Typically, in an electroetching process, the electrolyte may be configured not only to provide ionic contact between the electrodes, but also to remove the etched material from the surface of thereof, as well as to assist in the removal of gas bubbles that may form as metal dissolution by-product. The gas bubbles may hinder metal dissolution due to increased electrical resistance when present on the metal surface. The bubbles may further enter the area between the metal and the mask, loosening the contact therebetween and thus impairing the stenciling fidelity of the mask. The system of the present invention may be particularly advantageous in electroetching media containing gas bubbles, as the mask is configured to be maintained in close and constant contact with the moving foil throughout the entire electroetching process.

[0146] To afford controlled electroetching in accordance with (templating) the mask pattern, and to afford a perforation pattern in the foil that will be faithful to the pattern of the mask, at least a section of the foil is configured to be in intimate proximity, or contact with at least a section of the closed-band mask during the electroetching process. The section of the mask that contacts or is in intimate proximity with the corresponding section of the foil, and the section of the foil that contacts or is in intimate proximity with the corresponding section of the mask are also termed herein “contact sections”, and the area of the mutual contact is termed “contact region” or “perforation zone”. It is to be understood that during the continuous electroetching process, the foil is passed into the electroetching unit to be electroetched, and an unetched portion of the pristine foil continuously becomes the contact section to allow seamless etching of the entire foil length, wherein the contact section on the mask, being a circumferentially closed band, continuously changes and collectively spans the entire circumference of the mask. Alternatively, the mask can be seen as including a limited number of contact sections, the number of which depends on the length of the contact section of the foil and the total length of the mask (its circumference).

[0147] The term continuous in the context of the electroetching process according to the various aspects and embodiment of the present invention, is meant to encompass a process of electroetching of a continuous (long) foil, preferably, in a roll-to-roll configuration, wherein the foil may be advanced through the electroetching unit in a continuous manner (at a constant or changing rate) or incrementally, wherein the duration of the steps during which the foil is advanced, the advancement rate, and the waiting time between the steps may be adjusted in accordance with the electroetching conditions.

[0148] According to some embodiments, the contact section in the foil and the corresponding contact section the mask are in physical contact with one another, essentially over the entire contact sections, except the areas of the holes (voids) in the mask. Since the system operates in continuous motion of at least the foil and the mask, meaning that the contact sections change continuously, the phrase “essentially over the entire contact sections” is meant to address the dynamic state of the contact sections, stating that at any given timepoint during the process, the majority of the areas of the contact sections are in physical contact (zero distance), whereas some minor areas of the contact sections may be in intimate proximity with each other, and these areas change dynamically. In some embodiments, the contact section of the foil and the corresponding contact section of the mask, or parts thereof, are in intimate proximity with one-another, wherein “intimate proximity” refers to a distance of 0-0.5 mm. In some embodiments, in the context of the contact regions, the term “contact” is meant to encompass a range of states from complete physical contact over the entire area of the contact sections, via essentially over the entire contact sections, to intimate proximity over the entire area of the contact sections.

[0149] To provide a sufficiently large contact area between the closed band mask and the foil in a continuous manner, the contact section of the mask and the corresponding contact section of the foil are non-flat, preferably smoothly curved as a curved surface, e.g., following the curvature of an arch, a section of a circle or of an ellipse, wherein the shape of the contact section of the mask is configured to conform to the shape of the contact section of the foil (or vice versa). For example, the contact section of the foil may be convex (i.e., extending towards the contact section of the mask) and the contact section of the mask may be concave (i.e., curving inwards from the contact section of the foil). In another example, the contact section of the foil may be concave and the contact section of the mask may be convex.

[0150] The electroetching process, according to some embodiments of the present invention, takes place in a curved contact region. The contact region or the perforation zone, as this term is defined hereinabove, is afforded when pressing a mask to a pristine foil, and a curved contact region is afforded when at least one of the mask and the foil have a curved surface or are pressed against a curved surface. Preferably, the curved surface, and hence the resulting curved contact region or the abovementioned contact sections of the foil and the mask, are curved so as to inversely match (conform to) the curvature of the active surface of the cathode. For example, the shape of the contact sections of the mask and of the foil may further correspond to the shape of the active surface of the cathode and / or the curvature of a curved surface that forms a part of the lateral surface of a cylindrical or spherical anode (see, FIGs. 1A-B , FIGs. 2A-B , FIGs. 3A-B , and FIGs. 4A-B). A region formed between the cathode and the contact region of the foil and the mask, in which electroetching takes place when the cathode and the foil are in electrical contact and the electrolyte is present therebetween, is termed herein “electroetching zone”.

[0151] According to some aspects and embodiments of the present invention, there is provided a roll-to-roll foil electroetching system, comprising: an electroetching unit, configured to transform the starting foil into an electroetched foil upon the application of electric current and / or voltage; an input roll configured to feed the starting foil into the electroetching unit; and an output roll configured to collect the patterned foil, wherein the electroetching unit comprises: a cathode an elastic mask; two or more shafts, which hold the mask under tension; a vessel for holding and / or circulating a liquid electrolyte composition; a fluid transportation unit in fluid flow connection with the vessel; and a power supply, wherein the starting foil and the patterned foil is electrically conducting; wherein the mask has a circumferentially closed band form, having external surface that is electrically insulating, wherein the mask comprises a contact section positioned to contact a corresponding contact section of the foil such that the contact section of the mask has a curved shape, which conforms to a curvature of the contact section of the starting foil, wherein the contact section of the mask is positioned between the cathode and the contact section of the starting foil; wherein the fluid transportation unit is configured to direct a flow of the electrolyte composition supplied by the vessel to be tangential to the external surface of the mask along essentially an entire length of the contact portion of the mask; wherein upon feeding the starting foil by the input roll and / or collecting the patterned foil by the output roll, the mask and the starting foil are configured for coordinated motion while the starting foil is in contact with the mask; and the power supply is configured to apply voltage and / or current between the cathode and the contact section of the starting foil in the presence of the electrolyte composition.

[0152] The term “mask”, as used herein, refers to a perforated layer (i.e., a layer having through- holes therein), which has an electrically insulating surface, and which resists electroetching.

[0153] As detailed herein, the system includes, according to some embodiments, a fluid transportation unit in fluid flow connection with the vessel. According to some embodiments, the fluid transportation unit is configured to direct a flow of the electrolyte composition supplied by the vessel to be tangential to the external surface of the mask. According to some embodiments, the fluid transportation unit is configured to direct a flow of the electrolyte composition supplied by the vessel to be parallel to the external surface of the mask. Specifically, it was surprisingly found that directed and controlled electrolyte flow (possibly under pressure) into the area between the foil and the mask assembly and the cathode allows to remove etched metal from the foil surface and mask. It thus further allows to form perforation on thick foils. Previous system designs directing electrolyte flow through perforations were less successful with smaller mask holes due to bubbles and / or etched metal salt blocking mask holes, as the electrolyte flow was insufficient to remove these bubbles and / or etched metal salt from the mask holes.

[0154] It was further found that in the lack of flowing electrolyte perforation of thick foils is not allowed.

[0155] Specifically, the present system includes, according to some embodiments, means for directed and controlled electrolyte flow into the contact section of the starting foil and the mask. According to some embodiments, the system includes a liquid pump, configured to circulate the electrolyte composition, in a flow path between the electrode and the counter electrode. According to some embodiments, the liquid pump is configured to create fluid pressure. According to some embodiments, the fluid pressure is directing the flow of the electrolyte composition to be tangential to the external surface of the mask. According to some embodiments, the fluid pressure is directing the flow of the electrolyte composition to the contact section of the foil and the mask.

[0156] According to some embodiments, the system includes a liquid pump, configured to circulate the electrolyte composition, in a flow path between the electrode and the counter electrode along essentially an entire length of the contact portion of the mask. The phrase “essentially an entire length of the contact portion of the mask” refers to at least 80% of the length of the mask, at least 90% of the length of the mask or at least 95% of the length of the mask. Each possibility represents a separate embodiment of the invention.

[0157] It was further found that for even better contact of the electrolyte composition with the cathode, a split cathode may be used. According to some embodiments, the cathode is divided into two or more portions. According to some embodiments, the cathode is divided into two. According to some embodiments, the cathode is divided into two essentially equal sections. According to some embodiments, the fluid transportation unit is configured to direct electrolyte flow between said two sections facing the mask.

[0158] The electrode may be divided into two sections and the electrolyte flows therebetween. In such case the entire system may be rotated 90° counterclockwise, so that the cathode and the mask are positioned underneath the foil and the foil is pulled through the patterning region horizontally. The is exemplified in Fig. 3C herein.

[0159] In some embodiments, the electroetching process imparts a seamless repeating pattern of through-holes to the electrically conducting foil. In some embodiments, the system is configured to etch a seamless repeating pattern of through-holes in a continuous electrically conducting foil in a roll-to-roll configuration.

[0160] Advantageously the present electroetching system and process, allows the formation of small perforations (e.g., smaller than 6 mm in diameter). According to some embodiments, the system is configured to form perforations having a mean diameter lower than 6 mm, lower than 5mm, lower than 4mm, lower than 3 mm, lower than 2mm or lower than 1mm. Each possibility represents a separate embodiment of the invention. According to some embodiments, at least one of the input roll and output roll is a crowned roller. According to some embodiments, the crowned roller is configured to maintain alignment of the starting role with the mask in a lateral direction perpendicular to a direction of motion of the mask and the staring foil.

[0161] A “crowned roller” is a roll that has an arced surface across its face with the arc sweeping from the ends out toward the center of the roller face. The ends of the roller face are the smallest diameter while the roller diameter increases in equal increments across its’ face to the center. A crowned spreader roller can be manufactured from a variety of materials, such as steel, aluminum, stainless steel or plated aluminum or steel and can be rubber covered.

[0162] In some embodiments, the active surface of the cathode conforms to the curvature of the contact section of the foil. In further embodiments, the active surface of the cathode is curved.

[0163] The term “active surface”, in connection with a cathode or an anode, refers to a surface that faces the contact section of the foil during the electroetching process.

[0164] The cathode of the electroetching unit may be connected to a negative pole of the power supply. The contact section of the electrically conducting foil may be connected to a positive pole of the power supply. The electrical connection to the positive pole may be affected as known in the art, e.g., by means of an electrical conductor. The electroetching unit may further include an anode. For example, the contact section of the foil may physically contact such anode, thereby being connected to the positive pole of the power supply and held at a positive potential versus the cathode, to allow electroetching at the contact region of the foil. In some embodiments, the contact section of the foil is electrically connected to the positive pole of the power supply without directly contacting an anode. For example, a section of the metal foil that is not a contact section may be connected to the positive pole of the power supply, e.g., by wounding the foil over an electrically conductive shaft, cylinder or endless belt conveyer, wherein the electrically conductive shaft / cylinder / conveyer is connected to the positive pole. In some embodiments, the electrically conducting foil itself constitutes an anode in the electroetching process.

[0165] In some embodiments, the electroetching unit includes a curved surface. In some embodiments, the curved surface is electrically conductive, and the electrically conducting foil is connected to a positive pole of the power supply via the curved surface. In certain such embodiments, the curved surface may constitute an anode. In some embodiments, both the electrically conducting foil and the curved surface are connected to the positive pole of the power supply.

[0166] In some embodiments, the curved surface forms a part of the lateral surface of a cylinder or endless belt conveyer or a large sphere (such as having a diameter of 3 meters or above). In some embodiments, the cylinder or a conveyer element is rotatable, and configured for coordinated motion with the mask (see, FIGs. 1A-B).

[0167] As mentioned hereinabove, the contact section of the closed band mask has a curved shape corresponding to the contact section of the electrically-conducting foil, meaning that the contact section of the foil may also have a curved surface. The terms “correspond” “corresponding”, “conform” and “conforming”, as used herein in the context of a curved shape, refer to complementing curvatures, namely a combination of a convex and a concave shape or surface. It is to be understood that both the mask and the foil are in a form of a thin film, that is either continuous, as in the case of the foil, or closed band, as in the case of the mask, and as such may be permanently or temporarily shaped to form the corresponding curved contact sections.

[0168] The radius of the curvature of the contact section of the mask and of the foil may be selected to provide the desired length of the contact region and the electroetching zone and may range from about 10 cm to about 1,000 cm or more. The radius of the curvature may further be adjusted to the thickness and material properties of the mask and the foil, such as elongation, e.g., being below elongation at break value of the material.

[0169] The contact section of the foil may be held within the electroetching unit by wrapping over a stationary or moving object having a curved surface. In some embodiments, the foil is wrapped over a stationary or moving object having a convex surface that faces the foil. For example, the contact section of the foil may be wrapped over a portion of an outer (convex) surface of a mandrel, also termed herein “cylindrical mandrel”, “cylindrical drum” or “cylinder”. The terms “drum”, “cylinder” and “mandrel” are used herein interchangeably to refer to a curved surface over which the foil may be wrapped or wound to provide the curved shape of the contact section of the foil. The curved surface of the mandrel may also be a part of a large sphere. The mandrel may be rotated in a coordinated motion with the mask to allow continuous rolling of the foil within the electroetching unit.

[0170] According to some embodiments, the mask and the starting foil are configured for coordinated motion. According to some embodiments, the mask and the starting foil are configured for coordinated motion while said starting foil is in contact with said mask. According to some embodiments, upon feeding said starting foil by the input roll and / or collecting said patterned foil by the output roll, the mask and the starting foil are configured for coordinated motion.

[0171] According to some embodiments, the starting foil is pressed against the mask. According to some embodiments, the input roll, output roll or both are configured to transition the starting foil in a direction from the input roll to the output roll. According to some embodiments, the input roll is configured to transition the starting foil in a direction from the input roll to the output roll. According to some embodiments, the output roll is configured to transition the starting foil in a direction from the input roll to the output roll. According to some embodiments, the pressing and the transition of the starting foil are dragging the mask. According to some embodiments, the drag enables the coordinated motion of the foil and the mask.

[0172] The contact section of the foil may be wrapped over a convex surface of a non-rotating object. In some embodiments, continuous rolling of the foil may be assisted by providing one or more rotation shafts over which the foil is wound. Said non-rotating object may be stationary or moveable in a linear motion, for example, for establishing the desired distance between the foil and the mask and / or the active surface of the cathode. A rotation shaft, a.k.a. a rotation cylinder, is a mechanical part of a machine that is used to allow a sheet or a thread to glide there-over while passively rotating as a result of the movement of the sheet or thread (a passive rotation shaft), or used to move the sheet or thread by means of motorized axial rotation of the shaft and friction therebetween.

[0173] In order to further improve etched metal removal from the foil surface and / or from the mask a designated unit to remove etched metal from the electroetching system may be employed. In particular, etched metal particles may accumulate in holes of the mask and inhibit further electroetching through said holes, thereby negatively affecting the SRP of perforations etched in the foil. This is particularly important when manufacturing a perforated foil with a high open area (e.g., 15% and above) or when the mask hole diameter is relatively small (e.g., lower than 100 pm). Etched metal may include aluminum oxide or aluminum hydroxide, for example when aluminum foils are electroetched. Due to the limited solubility of such salts in electrolyte solutions, they often precipitate as particles, which can accumulate in the foil, mask or other parts of the system. It was found that in the absence of washing, holes size distribution is broad and hole shape is uneven (does not conform to the mask hole shape).

[0174] Thus, according to some embodiments, the system comprises a means to remove etched metal from the electroetching system. According to some embodiments, the system comprises a means to remove etched metal from the foil, the mask or both.

[0175] According to some embodiments, the electroetching unit comprises a means to remove etched metal from the mask.

[0176] According to some embodiments, an in-line mask washing unit may be added to the system to ensure that the holes of the mask are free from the etched metal salt prior to contacting the foil.

[0177] According to some embodiments, the electropatterning unit comprises a washing unit. According to some embodiments, the connectable to a washing liquid source. According to some embodiments, the liquid is a cleaning liquid. According to some embodiments, the liquid comprises water. According to some embodiments, the liquid is an aqueous composition. According to some embodiments, the aqueous composition is an aqueous solution. According to some embodiments, the washing unit comprises at least one nozzle facing a portion of the elastic mask and configured to rinse the portion of the starting foil with a washing liquid.

[0178] According to some embodiments, the washing unit comprises at least one nozzle. According to some embodiments, the washing unit comprises at least two nozzles. According to some embodiments, the washing unit comprises two nozzles.

[0179] According to some embodiments, the washing unit is configured to wash the portion of the mask with pressurized water. According to some embodiments, the portion of the mask if offset from the contact section of the mask with the foil. According to some embodiments, the portion of the mask if exposed and offset from the contact section of the mask with the foil and from the tension shafts. According to some embodiments, the portion of the mask is positioned between two tension shafts.

[0180] According to some embodiments, the washing unit comprises a wash head configured to sprinkle pressurized liquid towards the portion of the mask.

[0181] According to some embodiments, the washing unit further comprises an electroetched metal collection tray, in a for of a liquid reservoir, positioned to collected to washed electroetched metal. It is to be understood that the positioning of the collection tray is such it can collect a jet or spray of water that is washing the mask.

[0182] According to some embodiments, the system comprises an electroetched foil cleaning device. According to some embodiments, the electroetching unit comprises an electroetched foil cleaning device. According to some embodiments, the means to remove etched metal from the foil comprises an electroetched foil washing unit.

[0183] The electroetched foil washing unit may be similar to the mask washing unit, and each of the relevant embodiments that define the mask washing unit may similarly apply to the electroetched foil washing unit, besides its positioning. Specifically, the positioning of the electroetched foil washing unit is such that the electroetched foil washing unit can wash the portion of the electroetched with pressurized water. According to some embodiments, the portion of the electroetched foil if offset from the contact section of the mask with the foil. According to some embodiments, the portion of the mask is positioned between the contact section of the mask with the foil, and the output roll.

[0184] According to some embodiments, the system comprises an ultrasonic cleaning device. According to some embodiments, the electroetching unit comprises an ultrasonic cleaning device. According to some embodiments, the means to remove etched metal from the foil, the mask or both comprises an ultrasonic cleaning device.

[0185] According to some embodiments, the ultrasonic cleaning device comprises an ultrasonic transducer.

[0186] The ultrasonic cleaning device may be configured to transmit ultrasonic to the mask and / or to the electroetched foil. Also, two ultrasonic cleaning devices or an ultrasonic cleaning device with two transducers may be incorporated, according to some embodiments. Each possibility represents a separate embodiment of the invention.

[0187] According to some embodiments, an ultrasonic transducer may face a portion of the mask. The portion of the mask toward which the ultrasonic transducer may face may be as described for the portion of the mask that is washed by the washing unit. Therefore, each of the embodiments relating to the washed portion of the mask may similarly apply to the ultrasonic irradiated portion of the mask. The washed portion of the mask and the ultrasonic irradiated portion of the mask may be the same portion of different portions of the mask, which are defined under the definitions above, according to some embodiments. According to some embodiments, an ultrasonic transducer may face a portion of the electroetched foil. The portion of the electroetched foil toward which the ultrasonic transducer may face may be as described for the portion of the electroetched foil that is washed by the washing unit. Therefore, each of the embodiments relating to the washed portion of the electroetched foil may similarly apply to the ultrasonic irradiated portion of the electroetched foil. The washed portion of the mask and the ultrasonic irradiated portion of the electroetched foil may be the same portion of different portions of the electroetched foil, which are defined under the definitions above, according to some embodiments.

[0188] Another means of removing etched metal from the foil, the mask or both includes a filter, according to some embodiments. As detailed herein, the system can comprise an anode, according to some embodiments, which is positioned adjacent to the contact section.

[0189] The system may further comprise a liquid pump, configured to circulate the electrolyte composition, in a flow path between the electrode and the counter electrode, according to some embodiments. As mentioned, over time electroetched metal (e.g., Al(0H)3) may precipitate to the electrolyte composition, according to some embodiments. Thus, according to some embodiments, the system may further include a filter, which comprises a membrane, configure to filter undissolved solid particles from the electrolyte composition.

[0190] A tension shaft or cylinder may be used to maintain tension on the closed band mask by being mounted on a spring or other mechanism that allows it to move slightly against an opposing force (e.g., against the spring). As the closed band begins to roll, the tension shaft moves to compensate for the change in tension in the band, keeping the band taut.

[0191] The cylindrical mandrel may constitute an anode, i.e., being connected to the positive pole of the power supply. In some embodiments, at least a portion of the curved surface of the mandrel is electrically conducting. In some embodiments, the cylindrical mandrel is made of an electrically conducting material. The mandrel may be made of a solid electrically conducting material, i.e., its bulk being filled by said material. Alternatively, the mandrel may be a hollow electrically conducting mandrel.

[0192] In some embodiments, the bulk of the cylindrical mandrel is made of an electrically insulating material and the curved surface thereof is made of an electrically conducting material. For example, an electrically conducting sleeve may be mounted over the curved surface of an electrically insulating mandrel. Alternatively, the curved surface of the electrically insulating mandrel may be coated with an electrically conducting material, e.g., by electroless deposition.

[0193] In some embodiments, the bulk and / or the curved surface of the cylindrical mandrel are made of alternating electrically conducting and electrically insulating portions. For example, the mandrel may be mainly made of an electrically insulating material, while including insets of an electrically conducting material that spread radially from a center axis of the mandrel towards the curved surface thereof and are present on the curved surface. Without wishing to being bound by theory or mechanism of action, it is contemplated that such configuration may improve current distribution during the electroetching process.

[0194] In some embodiments, the cylindrical mandrel is electrically insulating. In some embodiments, the foil may be electrically connected to the positive pole of the power supply by means of the electrically conductive cylinder that is electrically connected to the positive pole and contacts the foil outside the contact region.

[0195] Non-limiting examples of electrically conducting and electrically insulating materials that may be used in the mandrel include metal, plated metals, and metal alloys, such as Al, Ni, Cu, Mg, Ti, steel, stainless steel, steel coated with chrome; polymers, such as polytetrafluoroethylene (PTFE, e.g., TEFLON™) and polyaryletherketone, e.g., PEEK™; carbon and / or graphite; ceramics; and polymer-coated metals.

[0196] The cathode may have an active surface facing the contact section of the mask, the shape of which corresponds or conforms to the shape of the contact section of the mask and / or the contact section of the foil. For example, the cathode may have a concave active surface that faces the contact section of the mask. In some embodiments, the mask encircles the cathode, and the cathode-mask assembly may be moved as one towards the foil to press the contact section of the mask against the curved contact section of the foil.

[0197] The cathode may be a dynamic cathode, e.g., a rotating cathode. Rotation of the cathode may assist in flowing of the electrolyte solution through the electroetching unit during the electroetching process. The cathode may further be used to deliver the electrolyte solution to the contact region, e.g., by spraying.

[0198] In some embodiments, the length of the active area of the cathode is smaller than the length of the contact region. Without being bound by any particular theory or mechanism of action, it is contemplated and assumed that restricting the length of the cathode active area relatively to the contact region may assist in preventing unwanted electroetching of the foil in the areas that are not in contact with the mask, such as before the point where such contact is established within the electroetching system. This may be particularly important when the foil, the mask, and the cathode are immersed into the electrolyte solution and controlling the contact area between the foil and the electrolyte solution is difficult.

[0199] The cathode may be made of any electrically conductive material that is inert to the electroetching medium and conditions of the electroetching process when used as a cathode. In some embodiments, the cathode is made of the same material as the electrically conducting foil, e.g., aluminum when patterning aluminum foil or copper when patterning copper foil. Non-limiting examples of cathode materials which can be used in combination with different types of electrically conductive foils include graphite, glassy carbon, stainless steel, and platinum.

[0200] According to some embodiments, the cathode can be made of conducting and nonconducting segments. According to some embodiments, such segmented configuration of the cathode enables to bring the cathode current density closer to the anode current density. Such configuration may be advantageous, e.g., in copper etching.

[0201] The mask may be an elastic mask or a rigid mask. In the context of the mask, the term "elastic" refers to the ability of the mask to stretch and contract without breaking while being turned, tensioned, flexed, twisted, and relaxed. The elasticity of the mask confers the ability of the mask to return to its original shape after being deformed, flexed, and relaxed by external forces. In the same context of a mask, the term “rigid” refers to the ability of the mask to maintain its shape under load, and to a mask that does not have the capacity to stretch and return to its original size, wherein in some embodiments a rigid mask can still bend and be wound around and driven by shafts. A mask, according to some embodiments of the present invention, may be elastic and flexible (bendable) as in the case of some polymeric masks, only flexible, namely essentially not stretchable but can be bend and twisted, as in the case of a malleable metal band, or rigid, which has a predefined and constant shape, as in case of a circular hard / rigid metal mask. Accordingly, bendable masks may be temporarily or permanently shaped (e.g., bent or stretched) to form the curved contact section, without necessarily being circular along the entire perimeter thereof. Rigid masks, on the other hand, should be pre-formed to have the circular shape to continuously provide the curved contact section upon rotation.

[0202] In some embodiments, the mask is an elastic mask. As such, the mask may be wound between two or more tension and or rotation shafts to allow continuous driving and / or rolling thereof. The elastic mask may further be tensioned between said two or more tension shafts.

[0203] In some embodiments, the elastic mask is temporarily shaped to form the corresponding curved contact section. For example, a contact section of the mask that is wound between two or more tension shafts may be pushed towards and pressed against the contact section of the foil having a convex shape. Additionally, or alternatively, the contact section of the foil having a convex shape may be pushed towards and pressed against the contact section of the mask that is wound between two or more tension shafts. The convex shape of the contact section of the foil may be provided by wrapping the contact section over a convex surface of a stationary or moving object, such as the cylindrical mandrel.

[0204] Reference is now made to FIGs. 1A-B, which present a schematic illustration of electroetching unit 10, according to some embodiments of the present invention, showing circumferentially closed band mask 11, wound and tensioned between tension shafts 12a and 12b, encircling concave cathode 13 and positioned close to cylindrical mandrel constituting anode 14 on which foil 15 is wrapped tightly over part of the convex surface of anode 14, wherein FIG. 1A shows electroetching unit 10 in the loading stage, before mask 11 is put in contact with foil 15 and before electric power is applied, and FIG. IB shows electroetching unit 10 in the electroetching stage, in which mask 11 contacts foil 15, whereas the dashed rectangle in FIG. IB marks the contact region between mask 11 and foil 15, including contact section Ila of mask 11 and contact section 15a of foil 15, and contact is made by moving tension shafts 12a and 12b towards anode 14, moving anode 14 towards tension shafts 12a and 12b, or a combination thereof, while tension shafts 12a and 12b may be put in coordinated rotary motion with anode 14, during which electrolyte is flown between cathode 13 and anode 14 (not shown) and electric power is applied to cathode 13 and anode 14 to effect electroetching of foil 15.

[0205] As can be reckoned from FIGs. 1A-B, the electroetching unit is configured to form indents or through-holes in the foil in a pattern that is templated (stenciled) by the pattern of the mask as a result of applying electric power between the cathode and the anode while continuously passing the tensioned foil through the electroetching unit, wherein the movement of the foil is coordinated with the movement of the mask, and flowing electrolyte solution at least though the part of the electroetching unit where the foil and the mask are positioned between the electrodes. In particular, as a result of the coordinated rotary motion of tension cylinders 12a and 12b and anode 14, new sections of foil 15 and of mask 11 come in contact forming new contact sections 15a and Ila, respectively, being positioned between the electrodes and in the electrolyte solution to allow continuous electroetching of the foil in accordance with the mask pattern. In this exemplary illustration, the electroetching unit includes a curved surface on which the curved perforation zone is formed, which is the curved surface of anode 14.

[0206] Reference is now made to FIGs. 2A-B, which present a schematic illustration of electroetching unit 20, according to some embodiments of the present invention, showing circumferentially closed band mask 21, wound and tensioned between tension shafts 22a and 22b, encircling concave cathode 23 and positioned near electrically insulating cylindrical mandrel 24 on which foil 25 is wrapped tightly over part of the convex surface of mandrel 24 and electrically conducting tension shaft 26, wherein FIG. 2A shows electroetching unit 20 in the loading stage, before mask 21 is put in contact with foil 25 and before electric power is applied, and FIG. 2B shows electroetching unit 20 in the electroetching stage, in which mask 21 contacts foil 25, whereas the dashed rectangle in FIG. 2B marks a contact region between mask 21 and foil 25, including contact section 21a of mask 21 and contact section 25a of foil 25, while tension shafts 22a and 22b may be put in coordinated rotary motion with mandrel 24, and, optionally, tension cylinder 26, during which electrolyte is flown between cathode 23 and foil 25 (not shown) and electric power is applied to cathode 23 and tension cylinder 26, which is connected to a positive pole of a power supply (not shown), thereby holding foil 25 at a positive voltage versus cathode 23, and effecting electroetching of foil 25.

[0207] FIG. 1C present a schematic illustration of the electroetching unit 10 shown in FIGs 1A- B, according to some embodiments of the present invention, wherein the concave cathode 13 is a split cathode, which include cathode portion 13a and cathode portion 13b, wherein the electrolyte can flow between cathode portion 13a and cathode portion 13b and anode 14, and wherein circumferentially closed band mask 11 is wound and tensioned between three tension shafts 12a, 12b and 12b.

[0208] FIG. ID present a schematic illustration of the electroetching unit 10 shown in FIGs 1A- B, according to some embodiments of the present invention, which further comprises a washing unit that includes a wash head 16, comprising one or more nozzles directed to closed band mask 11, a washing tray 17, positioned to collect washing liquid from closed band mask 11, and a wiper 18, that can prevent washing liquid from contacting foil 15; and further comprises a roller 19, configured to stretch closed band mask 11, thereby exposing its area to the nozzle(s). Roller 19 can also assist in centering the mask and preventing its axial motion. Thus, according to some embodiments, roller 19 may be a crowned roller. Roller 19 may be configured to stretch the mask 11 exposing its area to a nozzle(s) of the wash head 16. Wiper 18 may be to configured to prevent washing liquid contacting the foil.

[0209] As can be reckoned from FIGs. 2A-B, the electroetching unit is configured to form indents or through-holes in the foil in a pattern that is templated by the pattern of the mask as a result of applying electric power between the cathode and the foil while continuously passing the tensioned foil through the electroetching unit, wherein the movement of the foil is coordinated with the movement of the mask, and flowing electrolyte solution at least though the part of the electroetching unit where the mask is positioned between the cathode and the foil. In this exemplary illustration, the electroetching unit includes a curved surface on which the curved perforation zone is formed, which is the curved surface of cylindrical mandrel 24.

[0210] Reference is now made to FIGs. 3A-B, which present a schematic illustration of electroetching unit 30, according to some embodiments of the present invention, showing circumferentially closed band mask 31, wound and tensioned between tension shafts 32a and 32b, encircling concave cathode 33 and positioned near stationary anode 34 having a curved active surface on which foil 35 is wrapped tightly over a convex surface thereof and tension cylinder 36, wherein FIG. 3A shows electroetching unit 30 in the loading stage, before mask 31 is put in contact with foil 35 and before electric power is applied, and FIG. 3B shows electroetching unit 30 in the electroetching stage, in which tension cylinders 32a and 32b move towards anode 34 allowing contact between mask 31 and foil 35, while tension shafts 32a and 32b may be put in coordinated rotary motion with rotation shaft 36, during which electrolyte is flown between cathode 33 and stationary anode 34 and electric power is applied to cathode 33 and stationary anode 34, thereby effecting electroetching of foil 35.

[0211] In the exemplary illustration of FIGs. 3A-B, the electroetching unit includes a curved surface on which the curved perforation zone is formed, which is the curved active surface of stationary anode 34.

[0212] In some embodiments, the circumferentially closed band mask is a rigid mask. The rigid mask may have a constant shape and does not necessarily have to be wound over tension cylinders. The rigid mask may be in a form of a cylinder having a lateral surface serving as a curved surface. In some embodiments, the foil may be wound over two or more tension / rolling shafts, such that during the electroetching process the contact section of the mask has a convex shape and the contact section of the foil is concave, and the two corresponding contact sections contact each other to form a contact region.

[0213] Reference is now made to FIGs. 4A-B, which present a schematic illustration of electroetching unit 40, according to some embodiments of the present invention, showing rigid circumferentially closed band mask 41 having a cylinder shape viewed from the top, encircling rotating cathode 43 and positioned near foil 45 that is wound over tension / rotation shafts 46a and 46b, wherein tension shaft 26a is electrically conducting, the mask, the cathode, and the contact section of the starting foil being immersed in an electrolyte solution (not shown), wherein FIG. 4 A shows electroetching unit 40 in the loading stage, before mask 41 is put in contact with foil 45 and before electric power is applied, and FIG. 4B shows electroetching unit 40 in the electroetching stage, in which mask 41 contacts foil 45, wherein the contact may be affected by moving tension shafts 46a and 46b towards mask 41, moving mask 41 towards tension cylinders 46a and 46b, or a combination thereof, whereas tension shafts 46a and 46b may be put in coordinated rotary motion with mask 41, and electric power is applied to cathode 43 and tension shaft 46a, which is connected to a positive pole of a power supply (not shown), thereby holding foil 45 at a positive voltage versus cathode 43, and effecting electroetching of foil 45 while cathode 43 may be rotated to assist electrolyte solution flow between cathode 43 and foil 45. Cathode 43 has central portion 43a and curved blades 43b and 43c which are connected to central portion 43a and which outer surfaces constitute active surface of cathode 43, wherein the shape of curved blades 43b and 43c conforms to the shape of mask 41 to provide constant distance between the active surface of cathode 43 and the contact section of foil 45.

[0214] In this exemplary illustration the curved perforation zone is formed on rigid mask 41, which constitutes the curved surface of the electroetching unit.

[0215] The speed of the linear and rotary motion of tension and rotation shafts and rotating anodes, and the flow rate of the electrolyte, may determine the uniformity of the etching process, and therefore may be monitored and / or controlled throughout the process. The electroetching process conditions, such as parameters of the applied voltage or current, including but not limited to, amplitude, type (direct, pulsed, alternating, etc.), waveform, frequency, and step, distance between the electrodes (or between the cathode and the foil), and temperature and / or composition and properties of the electrolyte solution, may further be controlled.

[0216] The electroetching system may include a computerized control unit (CCU). The electroetching process which is affected by the electroetching system may be controlled by a CCU (a computer and a number of sensors and actuators, as these are known in the art) that monitors the voltage and / or current between the electrodes and / or the foil, and can also adjust the speed of the cylinders motion and the flow rate of the electrolyte to achieve the desired results. In general, a computerized control unit (CCU) is a device that uses a computer to control a system. The computer in a CCU is typically an embedded computer that is specifically designed for the task of controlling the system. The CCU may also include a number of sensors and actuators. Sensors are devices that measure physical quantities, such as electrical parameters, temperature, pH, conductivity, pressure, or flow rate, as well as chemical composition and concentration. Actuators are devices that can change physical quantities, such as the position of a valve or the speed of a motor. The computer in a CCU may use the data from the sensors to determine the current state of the system. The computer then may use this information to control the actuators in order to maintain the system in a desired state.

[0217] The CCU may be used to control the voltage and / or current between the electrodes and / or the starting foil. The voltage and / or current may determine the rate at which the foil is etched, wherein a higher voltage and current will typically result in a faster etching rate. The CCU may also control the flow rate of the electrolyte used in the electroetching process. A consistent flow of fresh electrolyte may result in a more uniform etching pattern. The term “electrolyte”, as used herein, refers to an ionically conductive and electrically insulating medium, typically an aqueous solution. The type of electrolyte used may depend on the material of the foil and the mask, and other considerations, such as toxicity, corrosion and environmental impact.

[0218] In some embodiments, the electrolyte may comprise an aqueous solution. The terms “aqueous electrolyte” and “aqueous solution”, as used herein, are meant to encompass liquid compositions containing water as a sole solvent, as well as containing organic solvents or additives, wherein the water content of the liquid phase is at least about 70% (w / w).

[0219] The ingredients of an exemplary electrolyte solution may include one or more of the following:

[0220] A salt of a metal to be electroetched, e.g., copper sulphate or copper chloride for electroetching copper, zinc sulphate for electroetching zinc, and ferrous sulphate for electroetching mild steel;

[0221] Chloride salts (such as sodium chloride, potassium chloride, or ammonium chloride) that increase the conductivity of the electrolyte solution, which allows the current to flow more easily; An acid, such as hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid, citric acid, or perchloric acid, to assist the etching process;

[0222] Water that serves as a carrier (solvent) for the salts, and, optionally, acids, and also helps to regulate the temperature of the electrolyte solution; and

[0223] An organic solvent, such as, but not limited to, isopropyl alcohol, ethyl alcohol, and ethylene glycol.

[0224] According to some embodiments, the electrolyte composition may be adjusted, e.g., using sodium nitrate instead of sodium chloride when electroetching copper, to prevent formation of copper chloride, which is a fine dispersion that gets easily adhered to the cathode, thereby reducing the distance between the cathode and the foil.

[0225] In addition to these ingredients, some electrolyte solutions may also contain other additives, such as dispersants, surfactants, buffers and organic compounds. These additives may improve the etching process and enhance the quality of the resultant electroetched foil, or to prevent the formation of corrosion products. The specific ingredients and concentrations of an electrolyte solution for electroetching will depend on the composition of the foil and the desired etching results.

[0226] Non-limiting examples of suitable electrolyte solutions include ferric chloride acidified with hydrochloric acid and dissolved in water; sodium chloride and citric acid dissolved in water; and sodium chloride and dispersant dissolved in water and ethanol.

[0227] The electroetching unit may further include a vessel for holding and / or circulating an electrolyte. In some embodiments, the power supply is configured to apply voltage and / or current between the cathode and the contact section of the foil in the presence of the electrolyte. Accordingly, the contact section of the foil, the contact section of the mask, and the cathode may be immersed in said electrolyte solution, or alternatively, the electrolyte solution may be flown from the vessel to the electroetching zone.

[0228] When using electrolyte bath, the electrolyte may be prevented from contacting the foil at the exposed areas thereof (i.e., that are not being in contact with the contact section of the mask), by immersing the foil into the electrolyte solution only at the contact section thereof, i.e., after the point of the initial contact with the mask. When using circulating electrolyte, the electrolyte may be prevented from contacting the foil at the exposed areas thereof (i.e., that are not being in contact with the contact section of the mask), by introducing the electrolyte into the electroetching system at a point that is past the initial contact of the foil with the mask.

[0229] The system may include a single electrolyte inlet or multiple electrolyte inlets. In certain embodiments, the system includes a single electrolyte inlet positioned between the cathode and the foil-mask assembly within the contact region. The electrolyte inlet may be configured to supply the electrolyte solution across the entire foil width. Spreading of the electrolyte may be assisted by the foil and the mask motion. The system may further include two or more seals at the periphery of the contact region (i.e., along or outside the outer edges of the foil and / or the mask) to restrict the flow of the electrolyte to the contact region and / or prevent its spreading outside of said region. The seals may be dynamic seals that do not interfere with the motion of the foil and / or the mask.

[0230] The system may further include an electrolyte circulation unit, that brings electrolyte solution to the perforation zone throughout the process, and may further control the temperature and possibly the chemical composition of the electrolyte. The electrolyte circulation unit is optionally configured to filter the electrolyte to remove debris and purge it from excess dissolved gases that are generated during the process. Dissolved gases that turn into gas bubbles may remain in the EU and adversely act as an insulator and stop the electroetching process, at least at the location of the bubbles. The electrolyte circulation unit may further include a reservoir, a waste bin, various pumps, chemical sensors (pH, ionic strength, viscosity, optical density), tubing and other arts.

[0231] The system may further include a patterned foil cleaning station, in which the patterned foil is rinsed off the electrolyte and debris, and optionally dried in preparation for its rewinding on the output roll. In some embodiments the electroetching system further includes an upstream foil cleaning station for preparing a foil for the electroetching process.

[0232] The system may further include a variety of motorized or passive shafts and cylinders, linear motion actuators, and various sensors that assist in controlling the process continuously.

[0233] Reference is now made to FIGs. 5A-D, which present a schematic drawing of electroetching system 500 (side view (Fig. 5A) and cross-sections (FIGs. 5B-5D), according to some embodiments of the present invention, that includes an electroetching unit including circumferentially closed band mask 51, wound and tensioned between tension shafts 52a, 52b, and 53c, encircling concave cathode 53 and positioned near electrically insulating cylindrical mandrel 54 on which foil 55 is wrapped tightly over part of the convex surface of mandrel 54 and electrically conducting tension shaft 56, wherein foil 55 is fed into the electroetching unit by input (feed) roll 57a and is collected onto output roll 57b, and wherein the electrolyte is introduced into the electroetching unit via electrolyte inlet 58.

[0234] The dashed line in FIG. 5C marks a contact region between mask 51 and foil 55. The dashed line in FIG. 5D schematically shows the electrolyte pathway through the electroetching unit. It can be seen that the electrolyte is introduced into the electroetching unit after point 59 where the contact between mask 51 and foil 55 is established. In other words, the electrolyte is introduced into the contact region of mask 51 and foil 55. It may further be seen that the length of the active surface of cathode 53 is smaller than the length of the contact region. The electroetching reaction is therefore confined to the area of the foil that is covered by the mask, thereby allowing controlled etching of the foil according to the mask perforation pattern.

[0235] Electrolyte inlet 58 may be connected through a tube to the vessel for holding and / or circulating the electrolyte. According to some embodiments, the tube can be orthogonal to the cross-section plane.

[0236] The electroetching system 500 can include one or more gaskets 511. The gasket(s) 511 can prevents electrolyte flow upwards. The electrolyte is thus enclosed from three sides and dragged downwards by gravitational force.

[0237] For the sake of clarity, element 512 represents the volume filled with the electrolyte composition.

[0238] Roll-to-roll electrodeposition system:

[0239] As known in the art, electrodeposition is a process that uses an electric current to deposit metal from a metal-ion containing solution over a conductive substrate surface by reducing the metal ions into metal. Electrodeposition may be used to form solid uniform foils, as well as foils having a predefined pattern on the metal surface or within the bulk. In the context of the present invention, the term “electrodeposition” refers to a process in which an electrically conducting surface, such as metal, is held at a negative potential against a counter electrode and is in ionic contact with the counter electrode via an electrolyte that contains metal ions, such that the metal ions are reduced on the surface of the electrically conducting surface and a solid metal is deposited thereon.

[0240] In some embodiments thereof, the present invention provides an electrodeposition system is configured to produce a very long (at least 1 meter and preferably more than 100 meters) patterned foil (metallic member) in a roll-to-roll configuration. The system includes an input (feed) roll that feeds an electrically conducting starting foil into an electrodeposition unit (EU), and an output roll for collecting the electrodeposited (patterned) foil, wherein said foil is supported on the starting foil. The electrodeposition process may include patterning a starting foil in the electrodeposition unit, which includes an electrically insulating mask in the form of a circumferentially closed band that exhibits a pattern of holes. A section of the mask is positioned between an anode and a section of the starting foil, and the starting foil is held at a negative voltage versus the anode by physically contacting a cathode or being in electrical contact with a negative pole of the power supply, wherein the anode is connected to the positive pole thereof. The section of the starting foil that contacts the section of the mask but is not covered by the mask material (i.e., the starting foil that is exposed through the holes of the mask) acts as a substrate for electrodeposition of metal, when a voltage is applied to the electrodes (namely, the anode and the foil or the cathode), wherein the electrodes are in ionic contact, e.g., by flowing an electrolyte solution therebetween, and wherein the electrolyte contains ions of the metal to be deposited on the starting foil, and the voltage or current is adjusted based on the type of the metal to be deposited and the anode. Accordingly, the metal is electrodeposited on the starting foil essentially in the areas that are not covered (masked) by the mask material forming a raised pattern, while the covered areas of the starting foil remain uncoated, thereby voids are formed in the electrodeposited layer in the areas that are covered by the mask. The shape of the raised pattern formed upon the starting foil directly corresponds to the perforation pattern of the mask and inversely corresponds to the negative space of the mask perforation (i.e., the material around the holes). In turn, the pattern of the voids of the electrodeposited foil inversely correlates with the perforation pattern of the mask (or directly correlates with the negative space of the mask hole pattern).

[0241] The electrodeposition system disclosed herein has similarities and shared components and features with the electroetching system disclosed herein. The electrodeposition system thus can include any of the features described for electroetching system, except from the specifics discussed herein with specific reference to the electrodeposition system. First, as electrodeposition and electroetching have opposite flow of electric current, the cathode and anode are reversed in function and position, therefore statements relating to the cathode in the electroetching system may be applied to the anode in the electrodeposition system and statements relating to the anode in the electroetching system may be applied to the cathode in the electrodeposition system. References to negative / positive poles may also reverse in meaning.

[0242] The starting metal foil may be solid (non-porous), porous, or perforated, wherein its perforation pattern may be selected to provide a patterned foil including raised elements with perforations therebetween, thereby enhancing corrugation of the patterned foil.

[0243] In the context of the present invention, the terms “electrodeposited foil”, “patterned foil”, “patterned metallic foil”, “porous foil”, “porous metallic foil”, and “metallic member” refer to a foil that is formed in the electrodeposition process upon the starting foil and encompass an assembly of the electrodeposited metal and the starting foil. The terms and phrases “a plurality of raised textural elements arranged in a pattern”, “a pattern of raised protrusions”, “a seamless repeating pattern of raised protrusions”, “electrodeposited layer”, “patterned layer”, “porous layer”, “electrodeposited coating”, “electrodeposited pattern”, “electrodeposited textural elements”, “patterned coating”, and “porous coating”, refer specifically to the metal that is deposited upon the starting foil.

[0244] The patterned foil may be a porous foil, i.e., containing pores. In the context of the present invention, the terms “pore” and “void”, which are used interchangeably, refer to hollow structures such as an indent, depression or recess formed within the foil not extending through the entirety of the thickness of the foil. The voids may be formed between two or more electrodeposited textural elements protruding from the starting foil surface. In some embodiments, the pattern of voids and / or the electrodeposited textural elements follows a seamless repeating pattern.

[0245] In the context of the present invention, the terms “structural element”, “surface element”, “protruding element”, “surface structure”, and “protruding structure”, which are used herein interchangeably when referring to the electrodeposited foil, are meant to encompass the metal material deposited upon the starting foil in the areas not screened by the mask material, i.e., the metal deposited between the voids caused by the mask. In the context of the electrodeposition, a high stenciling fidelity means that the pattern in the mask is reproduced in the electrodeposited foil with a high level of control on the accuracy and the consistency of the production and with little or no distortion or loss of detail, wherein the pattern created on the starting foil inversely correlates with the pattern in the mask (i.e., the through-holes are translated into raised textural elements).

[0246] In order to provide a long, patterned foil, the starting foil on which electrodeposition takes place, may be constantly passed through the electrodeposition unit and the mask may be rotated, such that a certain section of the mask is always positioned between the anode and a new section of the starting foil. The mask is stretched over the starting foil to eliminate contact between certain areas of the starting foil and the electrolyte, wherein said areas are configured for creating voids in the electrodeposited metal. The exposed sections of the starting foil require contact with the electrolyte to enable deposition of the metal ions from the electrolyte onto the starting foil. In order to afford for the constant contact between a section of the mask, the foil, and the electrolyte, advancement of the foil through the electrodeposition unit may be coordinated with the rotation of the mask. The flow of the electrolyte may be restricted to the contact region of the mask of the foil. The shape of the contact sections of the mask and of the starting foil may further correspond to the shape of the active surface of the anode and / or the curvature of a curved surface that forms a part of the lateral surface of a cylindrical or spherical cathode (see, FIGs. 11A-B, FIGs. 12A-B, FIGs. 13A-B, and FIGs. 14A-B). A region formed between the anode and the contact region of the foil and the mask, in which electrodeposition takes place when the anode and the starting foil are in electrical contact and the electrolyte is present therebetween, is termed herein “electrodeposition zone”.

[0247] According to some aspects and embodiments of the present invention, there is provided a roll-to-roll foil electrodeposition system, comprising: an electroetching unit is an electrodeposition unit configured to transform the starting metal foil into a foil patterned by electrochemically deposited metal upon the application of electric current and / or voltage; an input roll configured to feed the starting foil into the electrodeposition unit; and an output roll configured to collect the patterned foil, wherein the electrodeposition unit comprises: an electrode an elastic mask; two or more shafts, which hold the mask under tension; a vessel for holding and / or circulating a liquid electrolyte composition; a fluid transportation unit in fluid flow connection with the vessel; and a power supply, wherein the starting foil and the patterned foil is electrically conducting; wherein the mask has a circumferentially closed band form, having external surface that is electrically insulating, wherein the mask comprises a contact section positioned to contact a corresponding contact section of the foil such that the contact section of the mask has a curved shape, which conforms to a curvature of the contact section of the starting foil, wherein the contact section of the mask is positioned between the electrode and the contact section of the starting foil; wherein the fluid transportation unit is configured to direct a flow of the electrolyte composition supplied by the vessel to be tangential to the external surface of the mask along essentially an entire length of the contact portion of the mask; wherein upon feeding the starting foil by the input roll and / or collecting the patterned foil by the output roll, the mask and the starting foil are configured for coordinated motion while the starting foil is in contact with the mask; and the power supply is configured to apply voltage and / or current between the electrode and the contact section of the starting foil in the presence of the electrolyte composition.

[0248] The term “electrically conducting foil”, as used herein, refers to metal or metal alloy foils; composite foils; carbon and / or graphite; and electrically conducting polymers. Composite foils may contain metal, e.g., in a form of a metal layer disposed over an electrically insulating substrate, such as a polymer, or having metal regions dispersed throughout an electrically insulating material, wherein said metal regions are at least partially present on the surface of the foil. Electrically conducting polymers, which are also termed herein “intrinsically conducting polymers (ICPs)”, may be selected from linear-backbone "polymer blacks", such as, polyacetylene, polypyrrole, polyindole and polyaniline, and their copolymers; and aromatic cyclic polymers, such as poly(p-phenylene vinylene) (PPV). The mask may have an electrically insulating surface and which resists electrodeposition, namely, which prevents electrodeposition on a surface that is covered by the mask material.

[0249] The anode may be made of any electrically conductive material that is inert to the electrodeposition medium and conditions of the electrodeposition process when used as an anode. In some embodiments, the anode is made of a material that does not participate in the electrodeposition process (i.e., does not dissolve to be deposited on the starting foil). In some embodiments, the anode is made of the same material as the electrodeposited metal, e.g., copper, when forming a patterned copper layer or nickel, when forming a patterned nickel layer over the starting foil. In certain such embodiments, the anode may be at least partially dissolved during the electrodeposition process. In other words, such anode may be a consumable anode. Non-limiting examples of anode materials which can be used for electrodeposition of various types of metals include carbon-based such as graphite or glassy carbon, and metals, such as titanium, lead, tantalum, or niobium, as well ferrites and oxides thereof.

[0250] The metal that is electrodeposited in the electrodeposition system and process according to the various aspects and embodiments of the present invention may originate from metal ions present in the electrolyte and / or from the consumable anode.

[0251] The starting foil may be made of any electrically conducting material, as known in the art, such as, but not limited to metals, metal alloys, metal-containing composite materials, carbon-based materials, and electrically conducting polymers.

[0252] In some embodiments, the system is configured to provide a metal or metal-containing foil having a patterned multi-layer structure, wherein the different layers include different structure and / or arrangement of voids (including layers, which are essentially non- porous). Such multi-layer foils may be produced by changing the mask between electrodeposition of different layers.

[0253] Reference is now made to FIGs. 1A-B, which present a schematic illustration of electrodeposition unit 110, according to some embodiments of the present invention, showing circumferentially closed band mask 111, wound and tensioned between tension shafts 112a and 112b, encircling concave anode 113 and positioned close to cylindrical mandrel constituting cathode 114 on which foil 115 is wrapped tightly over part of the convex surface of cathode 114, wherein FIG. 11A shows electrodeposition unit 110 in the loading stage, before mask 111 is put in contact with starting foil 115 and before electric power is applied, and FIG. 11B shows electrodeposition unit 110 in the electrodeposition stage, in which mask 111 contacts starting foil 115, whereas the dashed rectangle in FIG. 11B marks the contact region between mask 111 and starting foil 115, including contact section Illa of mask 111 and contact section 115a of starting foil 115, and contact is made by moving tension shafts 112a and 112b towards cathode 114, moving cathode 114 towards tension shafts 112a and 112b, or a combination thereof, while tension shafts 112a and 112b may be put in coordinated rotary motion with cathode 114, during which electric power is applied to anode 113 and cathode 114, and electrolyte containing ions of metal to be electrodeposited is flown (not shown) between anode 113 and cathode 114 to effect electrodeposition of said metal on starting foil 115.

[0254] As can be reckoned from FIGs. 11A-B, the electrodeposition unit is configured to form a metal layer on the starting foil within the contact region upon foil areas that are not covered by the mask. The metal layer is therefore continuously formed in a pattern that is templated by the of mask perforations. The continuous electrodeposition occurs as a result of applying electric power between the cathode and the anode while continuously passing the tensioned starting foil through the electrodeposition unit, wherein the movement of the starting foil is coordinated with the movement of the mask, and flowing electrolyte solution at least though the part of the electrodeposition unit where the starting foil and the mask are positioned between the electrodes. In particular, as a result of the coordinated rotary motion of tension cylinders 112a and 112b and anode 114, new sections of starting foil 115 and of mask 111 come in contact forming new contact sections 115a and Illa, respectively, being positioned between the electrodes and in the electrolyte solution to allow continuous electrodeposition upon the foil in accordance with the mask pattern. In this exemplary illustration, the electrodeposition unit includes a curved surface on which the curved contact region is formed, which is the curved surface of cathode 114.

[0255] Reference is now made to FIGs. 12A-B, which present a schematic illustration of electrodeposition unit 120, according to some embodiments of the present invention, showing circumferentially closed band mask 121, wound and tensioned between tension shafts 122a and 122b, encircling concave anode 123 and positioned near electrically insulating cylindrical mandrel 124 on which starting foil 125 is wrapped tightly over part of the convex surface of mandrel 124 and electrically conducting tension shaft 126, wherein FIG. 12A shows electrodeposition unit 120 in the loading stage, before mask 121 is put in contact with starting foil 125 and before electric power is applied, and FIG. 12B shows electrodeposition unit 120 in the electrodeposition stage, in which mask 121 contacts starting foil 125, whereas the dashed rectangle in FIG. 12B marks a contact region between mask 121 and starting foil 125, including contact section 121a of mask 121 and contact section 125a of starting foil 125, while tension shafts 122a and 122b may be put in coordinated rotary motion with mandrel 24, and, optionally, tension cylinder 126, during which electric power is applied to anode 123 and tension cylinder 126, which is connected to a negative pole of a power supply (not shown) thereby holding starting foil 125 at a negative voltage versus anode 123, and electrolyte containing ions of metal to be electrodeposited is flown (not shown) between anode 123 and starting foil 125, to effect electrodeposition of said metal on starting foil 125. In this exemplary illustration, the electrodeposition unit includes a curved surface on which the curved contact region is formed, which is the curved surface of cylindrical mandrel 124.

[0256] Reference is now made to FIGs. 13A-B which present a schematic illustration of electrodeposition unit 130, according to some embodiments of the present invention, showing circumferentially closed band mask 131, wound and tensioned between tension shafts 132a and 132b, encircling concave anode 133 and positioned near stationary cathode 134 having a curved active surface on which starting foil 135 is wrapped tightly over a convex surface thereof and tension cylinder 136, wherein FIG. 13 A shows electrodeposition unit 130 in the loading stage, before mask 131 is put in contact with starting foil 135 and before electric power is applied, and FIG. 13B shows electrodeposition unit 130 in the electrodeposition stage, in which tension cylinders 132a and 132b move towards cathode 134 allowing contact between mask 31 and starting foil 135, while tension shafts 32a and 132b may be put in coordinated rotary motion with rotation shaft 136, during which electric power is applied to anode 133 and stationary cathode 134 and electrolyte ions of metal to be electrodeposited is flown (not shown) between anode 33 and stationary cathode 134 and to effect electrodeposition of foil said metal on 135. In this exemplary illustration, the electrodeposition unit includes a curved surface on which the curved contact region is formed, which is the curved active surface of stationary cathode 134. Reference is now made to FIGs. 14A-B which present a schematic illustration of electrodeposition unit 140, according to some embodiments of the present invention, showing rigid circumferentially closed band mask 411 having a cylinder shape viewed from the top, encircling rotating anode 143 and positioned near starting foil 145 that is wound over tension / rotation shafts 146a and 146b, wherein tension shaft 126a is electrically conducting, the mask, the anode, and the contact section of the starting foil being immersed in an electrolyte solution containing ions of metal to be electrodeposited (not shown), wherein FIG. 14A shows electrodeposition unit 140 in the loading stage, before mask 141 is put in contact with starting foil 145 and before electric power is applied, and FIG. 14B shows electrodeposition unit 140 in the electrodeposition stage, in which mask 141 contacts starting foil 145, wherein the contact may be affected by moving tension shafts 146a and 146b towards mask 141, moving mask 141 towards tension cylinders 146a and 146b, or a combination thereof, whereas tension shafts 146a and 146b may be put in coordinated rotary motion with mask 141, and electric power is applied to anode 143 and tension shaft 146a, which is connected to a negative pole of a power supply (not shown), thereby holding starting foil 145 at a negative voltage versus anode 143, and effecting electrodeposition of the metal ions from the electrolyte on starting foil 145, while anode 143 may be rotated to assist electrolyte solution flow between anode 143 and starting foil 145. Anode 143 has central portion 143a and curved blades 143b and 143c which are connected to central portion 143a and which outer surfaces constitute active surface of anode 143, wherein the shape of curved blades 143b and 143c conforms to the shape of mask 141 to provide constant distance between the active surface of anode 143 and the contact section of starting foil 145. In this exemplary illustration, the curved contact region is formed on rigid mask 141, which constitutes the curved surface of the electrodeposition unit.

[0257] The ingredients of an exemplary electrolyte solution suitable for electrodeposition may include one or more of the following:

[0258] A salt of a metal to be electrodeposited, e.g., copper sulphate or copper tetrafluoroborate for electrodeposition of copper, and nickel sulphate, nickel sulfamate, or nickel chloride for electrodeposition of nickel. The salt may be obtained by dissolving said metal in a strong acid containing the salt anion; Chloride salts (such as sodium chloride, potassium chloride, or ammonium chloride) that increase the conductivity of the electrolyte solution, which allows the current to flow more easily;

[0259] An acid, such as sulfuric acid, boric acid, fluoroboric acid, or sulfamic acid, to dissolve the metal and / or assist the deposition process;

[0260] Water that serves as a carrier (solvent) for the salts, and, optionally, acids, and also helps to regulate the temperature of the electrolyte solution.

[0261] In addition to these ingredients, some electrolyte solutions may also contain other additives, such as dispersants, surfactants, buffers and organic solvents and compounds. These additives may improve the deposition process and enhance the quality of the resultant electrodeposited foil, or to prevent the formation of reaction by-products. The specific ingredients and concentrations of an electrolyte solution for electrodeposition will depend on the composition of the foil and the desired coating results.

[0262] One non-limiting example of electrolyte solution suitable for copper electrodeposition includes copper dissolved in sulfuric acid and a chloride salt.

[0263] The system may further include a passivation unit or chemical treatment unit, as known in the art.

[0264] Reference is now made to FIGs. 15A-D, which present a schematic drawing of electrodeposition system 1500 (side view (FIG. 15A) and cross-sections (FIGs. 15B- 15D), according to some embodiments of the present invention, that includes an electrodeposition unit including circumferentially closed band mask 151, wound and tensioned between tension shafts 152a, 152b, and 153c, encircling concave anode 153 and positioned near electrically insulating cylindrical mandrel 154 on which starting foil 155 is wrapped tightly over part of the convex surface of mandrel 154 and electrically conducting tension shaft 156, wherein starting foil 155 is fed into the electrodeposition unit by input (feed) roll 157a and is collected onto output roll 157b, and wherein the electrolyte is introduced into the electrodeposition unit via electrolyte inlet 158. The dashed line in FIG. 15C marks a contact region between mask 151 and starting foil 155. The dashed line in FIG. 15D schematically shows the electrolyte pathway through the electrodeposition unit. It can be seen that the electrolyte is introduced into the electrodeposition unit after point 159 where the contact between mask 151 and starting foil 155 is established. In other words, the electrolyte is introduced into the contact region of mask 151 and starting foil 155. It may further be seen that the length of the active surface of anode 153 is smaller than the length of the contact region. The electrodeposition reaction is therefore confined to the area of the starting foil that is covered by the mask, thereby allowing controlled metal deposition on the foil according to the mask perforation pattern.

[0265] An SRP-template mask:

[0266] The uniformity of the perforation / electrodepo sited pattern in a patterned foil is critical, inter alia, when the metallic member is used as a current collector in a lithium-ion battery. Hence, the present invention provides a solution to the problem of forming a consistent, uniform and seamlessly repeated pattern of through-hole or sprotruding elements and / or voids in a very long conductive foil. Since industrial processes require the metallic member to be provided in the form of a roll of a long continuous member, and since the member should not exhibit breaks or gaps which are not a part of the desired pattern, or unintended variations of the through-holes, surface and / or bulk pattern, the present inventors devised an SRP-template mask in the form of circumferentially closed band or ribbon (loop) mask, made of an electrically insulating material or composite material, that is essentially inert in the operating conditions of the electropatterning unit (electrochemically-stable), that exhibits a seamless repeating pattern of holes.

[0267] Thus, according to an aspect of some embodiments of the present invention, there is provided a circumferentially closed gap mask, having a seamlessly-repeating pattern of holes, and referred to herein as an “SRP-template mask”. Herein and throughout, the term “mask” encompasses the term “SRP-template mask”, which is a mask exhibiting a seamlessly -repeating pattern (SRP) of holes that can be used to form an SRP on a substrate (e.g., a metal foil).

[0268] The terms “essentially inert” and "electrochemically-stable material" refer to a property of a material that does not undergo significant changes in its properties when it is exposed to an electrolyte or to an electric current in an electrolyte. This is important for electroetching masks because the mask needs to be able to withstand the electroetching conditions without dissolving or corroding. The mask’s material is selected such that it is essentially resistant to etching, dissolution, corrosion and mechanical wear and tear, so it can sustain long periods of operation under electroetching / electrodeposition conditions. In the context of the mask, a circumferentially closed ribbon or band is a shape that has no open ends. It is a continuous curve that forms a loop. A closed ribbon can have any width or length, but no open ends.

[0269] FIG. 6 is a schematic illustration of an exemplary mask, or SRP-template mask, according to embodiments of the present invention, showing a circumferentially closed band (a loop), exhibiting a seamless repeating patten, exemplified by an exemplary pattern of hexagonal holes shown in the enlarge circle.

[0270] The material or composite material from which a mask, as well as the presently disclosed SRP-template mask, is made of is an electrochemically-stable material. There are a number of materials that that may be used for forming the mask, such as the SRP-template mask provided herein, which include, without limitation:

[0271] Kapton®: Kapton® is a brand name for a type of polyimide that is known for its high temperature resistance. It is often used in applications where the material needs to withstand high temperatures, such as in aerospace and electronics applications. The generic name for Kapton® is polyimide.

[0272] Polyimide: Polyimide is a synthetic polymer that is known for its high strength, toughness, and chemical resistance. It is often used in applications where high performance and durability are required, such as in the aerospace and electronics industries. Polyimide is a synthetic polymer that is made from two monomers, pyromellitic dianhydride (PMDA) and 4, 4'-oxy diphenylamine (ODA). The monomers are linked together through condensation reactions to form a long, chain-like molecule. PTFE: Polytetrafluoroethylene (PTFE), also known as Teflon, is another synthetic polymer that is known for its excellent electrical and chemical resistance. It is often used in applications where a non-stick surface is required, such as in cookware and medical implants.

[0273] Parylene: Parylene is a generic name for a group of polymer coating materials that are optionally dielectric and are commonly used to protect electronic components, medical devices, and other objects from moisture, chemicals, and other contaminants. Parylene coatings are typically applied by chemical vapor deposition (CVD), which means that they are deposited on the surface of the object from a gaseous state. This process allows for the creation of thin, uniform coatings that conform to the surface of the object, even in complex shapes. Composite materials which are suitable for use in the context of a circumferentially closed band mask, such as an SRP-template mask, include core-coat composites, namely a base material that is coated with a highly resistant coat material. Masks made from less resistant metals can be coated with an electrically insulating and electrochemically-stable material, such as a polymer, e.g., parylene. A non-limiting example of a base material is stainless steel. Stainless steel is an alloy of iron that contains chromium and other elements. It is known for its high strength, corrosion resistance, and lasting luster. Stainless steel is often used in applications where a durable and corrosion-resistant material is required, and may be further coated by a polymer, such as polyimide to improves its corrosion resistance.

[0274] Composite materials which can be used to construct a mask, such as the SRP-template mask, include, without limitation, a polymer-coated metal, e.g., parylene-coated nickel, a layered composite of different metals and polymers, as well as some woven materials such as fiberglass.

[0275] The specific material or composite material that is used to make the mask, such as the SRP-template mask, will depend on the specific application. For example, if the mask is being used to etch under corrosive conditions, then a material with high chemical resistance, such as PTFE, would be a preferred choice for the mask or for a coating of the mask. If the mask is being used to etch at high temperatures, then a material with high temperature resistance, such as Kapton®, would be a preferred choice for the mask or for a coating of the mask.

[0276] In some embodiments, the mask is made of a hydrophilic material. Without wishing to being bound by theory or mechanism of action, it is contemplated that decreasing hydrophobicity of the mask may improve one or more process parameters, such as stenciling fidelity, life-span, electrolyte flow, and the like. For example, the hydrophilic surface of the mask may improve electrolyte flow within the pores of the mask. The term “hydrophilic”, as used herein, refers to the wettability of the mask by water or the electrolyte solution, and may be defined by the contact angle between the mask surface and water or electrolyte. In some embodiments, the contact angle between water or electrolyte and the mask surface is less than 90°. In certain embodiments, the contact angle is less than 80°, less than 70°, or less than 60°. The mask may be made of a hydrophobic material that is treated to improve its wetting ability by electrolyte. In some embodiments, the outer surface of the mask that is configured to contact the foil is rendered hydrophilic by a surface treatment, such as but not limited to, laser etching.

[0277] As mentioned hereinabove, the mask may be either elastic or rigid, i.e., having a flexible or stable shape. The choice of the mask material may also be made based on the desired elasticity of the mask.

[0278] According to some embodiments, the mask comprises a hydrophilic material. According to some embodiments, the mask is composed of a polymer or a polymer-coated metal. According to some embodiments, the mask is composed of a hydrophilic polymer or a hydrophilic polymer-coated metal. Each possibility represents a separate embodiment of the invention. According to some embodiments, the polymer or polymer coating comprises polyamide. According to some embodiments, the mask comprises a polyamide film. Without wishing to be bound by any theory of mechanism of action, hydrophilic mask may be important for electrolyte removal.

[0279] According to some embodiments, the mask comprises at least one surface, which is electrically insulating. According to some embodiments, the electrically insulating surface is the mask external surface, which comes in contact with the foil.

[0280] The mask may have an essentially smooth outer surface, including at the edges of the perforations. In some embodiments, the mask has an essentially smooth inner surface. The term “essentially smooth”, as used herein, refers in some embodiments to a surface roughness (Ra) of 1 pm or less. In some embodiments, the surface roughness of the mask is below 0.5 pm. It is to be understood that the term “surface roughness” relates to structural irregularities on the surface that rea not the intentionally formed through-holes of the mask. In some embodiments, the surface of the through-hole walls within the mask is essentially smooth.

[0281] The thickness of the mask, such as the SRP-template mask, is related to several factors that affect the process, such as mechanical aptitude and stenciling fidelity. A too thin mask may have a short life-span (short usability term), and may be more difficult to control, drive and manipulate around the various shafts and other moving part of the drive-train. A too thick mask may not be flexible enough to make close contact at the contact region, or be harder to manipulate around the various shafts and other moving parts of the drive-train. Additionally, higher thickness of the mask may limit diffusion of the etched foil material from the exposed areas. Furthermore, a too thick mask may have a negative effect on the stenciling fidelity, namely lower the resemblance between the pattern of the mask and the resulting pattern on the perforated foil. The thickness of the mask may affect the local composition and properties of the electrolyte solution at the exposed areas of the starting foil (i.e., areas which are not covered by the mask during electrodeposition within the contact region). Thicker masks, however, may allow producing thicker patterned layers upon the starting foil. Preferably, the thickness of the electrodeposited layer is essentially equal to, or smaller than the thickness of the mask.

[0282] The thickness of the mask, such as the SRP-template mask, suitable for use in the electroething systems and methods of the present invention may range from about 5 pm to about 100 pm. In some embodiments, the thickness of the mask ranges from about 5 pm to about 80 pm. In further embodiments, the thickness of the mask ranges from about 5 pm to about 60 pm. The thickness of the mask, such as the SRP-template mask, suitable for use in the electrodeposition systems and methods of the present invention may range from about 20 pm to about 300 pm. In some embodiments, the thickness of the mask ranges from about 50 pm to about 200 pm. In some embodiments, the thickness of the mask is at least about 25 pm. In some embodiments, the thickness of the mask is at least about 50 pm.

[0283] According to some embodiments, the mask exhibits a seamless repeating patten (SRP) of through-holes. According to some embodiments, the through-holes have an opening dimension of about 10-2,000 pm, including each value and sub-range within the specified range. According to some embodiments, the openings have mean diameter of below 100 pm. According to some embodiments, the openings have mean diameter of below 80 pm.

[0284] According to some embodiments, the openings have mean diameter of below 60 pm.

[0285] According to some embodiments, the openings have mean diameter of below 40 pm.

[0286] According to some embodiments, the openings have mean diameter of below 30 pm.

[0287] According to some embodiments, the openings have average diameter of below 100 pm.

[0288] According to some embodiments, the openings have average diameter of below 80 pm.

[0289] According to some embodiments, the openings have average diameter of below 60 pm.

[0290] According to some embodiments, the openings have average diameter of below 40 pm.

[0291] According to some embodiments, the openings have average diameter of below 30 pm.

[0292] It is to be understood that when referring to the contact section of the mask, the term “contact section” encompasses both the continuous solid area of the mask (where there are no holes) and the areas of the holes of the mask. This is to distinguish between the areas within the contact region in which there is no contact between the mask and the starting foil due to mask perforation but there is a physical contact between the mask and the starting foil, and areas outside the contact region, in which there is no physical contact between the mask and the starting foil.

[0293] The mask may be wider than the starting foil, e.g., by at least about 1 %, 5 %, 10 %, or more. The larger width of the mask may prevent uncontrolled etching of- or electrodeposition on the foil edges. The larger width of the mask may also be used to seal the electropatterning unit, such that the flow of the electrolyte is confined to the contact region.

[0294] In the context of the present invention and as afforded by the electropatterning system as disclosed herein, the circumferentially closed band mask is taken as an endless / continuous strip, with no apparent ends, no apparent seam, stitch or closure mark (unless deliberately introduced to produce such seams on the starting foil). To impart a uniform and seamless pattern such as a plurality of indents or perforation or protrusions to the foil during the electropatterning process, the mask is a SRP-template mask that is characterized, inter alia, by a non-random, and purposely designed seamless repeating pattern (SRP) of holes spanning essentially the entire area of the strip (except in the margins, in some embodiments), closed into a band or ribbon without visible or tangible boundaries or irregular / arbitrary / random transitions between the repeating pattern motifs or within the motifs. The SRP of holes in the mask is also continuous, namely has no sign of a beginning or an end along the circumference of the band (see, FIG. 6).

[0295] As used herein, the terms “template”, “stencil” and “patterned” with reference to a mask, refer to a purposely designed and engineered closed band having regularly-shaped, regularly-spaced, and / or regularly-oriented holes (also referred to herein interchangeably as “textural elements”) in / on its surface.

[0296] As used herein, the phrase “seamless repeating pattern”, abbreviated herein to “SRP”, refers to a pattern that spans an undefined and unlimited surface without visible transitions or boundaries. An SRP is a continuous repeating pattern of textural elements that consists of repeating elements arranged in a two-dimensional format, such as a geometric shape or a decorative design. An SRP continues indefinitely in all directions, creating a seamless visual effect. This type of pattern is often used in textiles, wallpaper, flooring, and other decorative materials, as well as in graphic design, packaging, and branding. As discussed herein, an SRP can be defined by a repeating pattern unit, whereas placing a plurality of such units intimately adjacent (juxtaposed) to each other will afford the SRP. The repeating unit is referred to herein as a tile or a motif.

[0297] The motif is defined by one or more textural elements, whereas each motif blends into neighboring motifs to achieve the SRP. In the context of the present invention, the motif includes textural elements in the forms of holes (i.e., through- holes, perforations, apertures, through-windows), whereas the entire SRP can be defined by the repeating motif. The arrangement of any given textural elements in the seamless repeating pattern characterizing the SRP-template mask provided herewith is controlled (non-random), as opposed to a random distribution of similar textural elements over a similar area; hence, the SRP characterizing the SRP-template mask provided herein (and the resulting patterned metallic member) is non-random by definition.

[0298] The coverage of a planar surface, such as a surface of the SRP-template mask, with the aforementioned SRP, essentially follows any standard tessellation or tiling approach, using one or more geometric shapes (tiles; motifs) with no overlaps and no gaps. While some embodiments of the present invention are drawn to a flat surface, which is essentially a two-dimensional entity if the thickness is disregarded, is noted that tessellation can be generalized to higher dimensions and a variety of geometries. In some embodiments, the SRP is afforded by a periodic tiling, whereas some embodiments include regular tiling with regular polygonal tiles, all having the same shape, and some embodiments include semiregular tiling with regular tiles of more than one shape and with every corner identically arranged.

[0299] The terms “motif’ or “tile”, as used herein, refer to the smallest and simplest single textural element, or non-repeating group of textural elements, the repetition of which forms and defines the SRP. In the context of the present invention, a motif is closely related to a unit cell in a 3D lattice (a crystal / lattice), whereas the SRP is form by repeating the motif in the plane to any direction on the plane. Within a motif there can one textural element, or more than one textural elements. In some embodiments, the motif includes more than one textural elements that relate to one another by symmetry operations in the 2D plane, such as translation, rotation and reflection transformation operations. In some embodiments, the motif includes more than one textural elements that are arranged non- symmetrically with respect to one-another, or more than one textural elements having different size / shape. It is to be understood that within a single tile the textural elements should not necessarily be arranged in a symmetrical or ordered manner. A flat plane, or SRP, can be fully tiled (covered) with triangular, rectangular and hexagonal polygons (tiles), each having one or more textural elements arranged within. Rectangular and hexagonal tiles can be placed using the same tile orientation (only translation, no rotation), while triangular tiles are placed with a 600rotation (translation and rotation). An example of a simple motif is a round dot, the expression of which can be a hole, whereas its SRP can be a square or hexagonal circle packing where the circles are evenly spaced, and in the case of through-holes, do not touch each other to allow continuous material therebetween).

[0300] Practically, in some embodiments, the SRP-template mask exhibits the SRP over the entire area thereof, from edge to edge; in some embodiments, the SRP spans the major area of the SRP-template mask, leaving narrow margins along its edges due to technical / practical requirements of industrial processing machinery. By margins, it is meant that the SRP-template mask does not exhibit the SRP in the area regarded as the margins, wherein the SRP-template mask can be intact or have a different pattern than the SRP. In some embodiments, the margins extend on each edge of the mask, and in some embodiments, the margins span less than 1 %, less than 2 %, less than 5 %, less than 10 %, less than 20%, or less than 30% of the total width of the SRP-template mask. In some embodiments, the margins extend on each edge of the mask, and in some embodiments, the margins span at least 1 %, at least 2 %, at least 5 %, at least 10 %, at least 20%, or at least 30% of the total width of the SRP-template mask. In some embodiments, one or more non-patterned strips are present near or at the center along the long axis of the SRP-template mask, designed for practical and industrial purposes, such as cutting the resulting member to narrower strips. In such embodiments, the majority of the SRP-template mask includes an SRP while narrow strips of pristine mask separate broad strips of patterned mask.

[0301] The mask may include a number of different SRP patterns along its width and / or length. For example, when using a relatively wide mask and starting foil, different patterned foil sections may be produced along the foil length. The patterned foil with different pattern sections may be used as it or cut into separate sections to obtain narrower long foils with a single type of pattern. Alternatively, when using a mask with a relatively large circumference, different patterned foil sections may be produced along the foil width. The patterned foil with different pattern sections may be used as it or cut into separate sections to obtain wide and short foils with a single type of pattern.

[0302] The seamless repeating pattern, according to some embodiments of the present invention, is mathematically defined or constructed. In some embodiments, the SRP is generated by machine learning, based on the requirements of the intended patterned foil.

[0303] It is to be understood that the mask may not necessarily be the SRP mask. For example, when producing a continuous patterned foil which is configured to be cut into discrete sections along its length, a seamless pattern is not essential. Additionally, the through- holes may be arranged within the mask in a non-symmetrical manner (e.g., a random manner), which is, however, predefined to produce the desired pattern structure on / within the starting foil.

[0304] Textural elements:

[0305] In some embodiments, the textural elements of the mask, such as the SRP-template mask, are small through-holes. According to embodiments of the present invention, the holes can take any shape and orientation, including round, oval, rectangular, triangular, polygon, hexagonal, rounded polygon, diamond or odd shaped. Round holes may be used to produce rod- or cone-like protruding elements on the starting foil surface, while polygonal holes may be used to form truncated and / or augmented pyramidal protrusions, and the likes. In certain embodiments, the holes are round, i.e., having a circular crosssection.

[0306] With respect to electrodeposition, the electrodeposition process and tools provided herein may also be used to afford a patterned foil having a protruding pattern that resembles the protruding pattern of a steel diamond plate, also known as a checker plate, a deck plate, a floor plate, a non-slip plate or a tread plate, which is a type of metal sheet that has a raised diamond lug pattern on one side and is smooth on the other side. To afford such a pattern, the holes may have the shape of a slit, a slot, a notch, a crack, a chink, or a cleft, with a ratio between width and length of up to 1:10,000. For example, slit-shaped holes impart an elongated protrusion or bulge on the starting foil; such elongated textural features may further exhibit particular relative orientation that affords intricate patterns, such as found in checker corrugated metal plates. This a type of pattern typically exhibits a series of raised angular, and symmetrical diamond- or linear-shaped ridges that are onto the surface of a metal sheet or foil. A checker corrugated metal plate is a type of sheet metal that has a checkerboard pattern of relatively-oriented and spaced-apart ridges. The height of the ridges and the width of the spaces between them can vary, and the textural features of the resulting pattered metal foil may be characterized by the following: The ridges are the raised portions of the pattered foil, and may exhibit V-shaped perpendicular cross-section; the spaces are the areas between the ridges, which are typically flat and smooth; and the ridges on such patterned foil are typically found in two orientations that are perpendicular to one-another.

[0307] An alternative definition of the SRP describes the SRP-template mask as a foil having a patterned surface, wherein the patterned surface is a porous surface having a designed pore location distribution (PLD), wherein the pores are through-holes. In some embodiments, the pores are located at regularly spaced intervals on the SRP-template mask. In some embodiments, the SRP-template mask has different sized pores at different locations on the SRP-template mask. In some embodiments, the SRP-template mask has different types of pores at different locations on the SRP-template mask. In some embodiments, the SRP-template mask has different shapes of pores at different locations on the SRP-template mask. In some embodiments, the SRP-template mask has pores which are aligned in straight lines. In some embodiments, the SRP-template mask has pores which are aligned in lines which are tilted at an angle with respect to an edge of the SRP-template mask.

[0308] As used herein, the term “size” refers to a characteristic dimension of an object, a structural element, or a textural element. When referring to the size of a plurality of objects, it refers to the average value obtained by measuring the size of a representative group of objects. A size of an object that is circular can refer to a diameter of the object. In the case of an object that is non-circular, a size of the non-circular object can refer to a diameter of a corresponding circular object, where the corresponding circular object exhibits or has a particular set of derivable or measurable characteristics that are substantially the same as those of the non-circular object. Alternatively, or in conjunction, a size of a non-circular object can refer to an average of various orthogonal dimensions of the object. Thus, for example, a size of an object that is a conic section (e.g., an ellipse) can refer to an average of a major axis and a minor axis of the object. In some embodiments, the term “size” refers to an equivalent circular radius.

[0309] When referring to a set of objects as having a particular size, it is contemplated that the objects can have a distribution of sizes around the particular size. Thus, as used herein, a size of a set of objects can refer to a typical size of a distribution of sizes, such as an average size, a median size, or a peak size.

[0310] As discussed hereinabove, perforation of the SRP-template mask follows a seamless repeating pattern, or SRP, which can be defined by tangent tiles or motifs within which the holes, or the textural elements, are positioned. An SRP is formed by filling the plane with the tiles. A tile may include a part of a (symmetric) hole, a single hole or any shape, or more than one hole of identical or different shapes (a mixture of shapes) and / or parts thereof.

[0311] In some embodiments, a through-hole may have parallel walls, being perpendicular to the plane of the mask (a cylinder- shaped hole). In some embodiments, a through-hole may have a tapered shape, or slanted walls, making the one opening of the through-hole different in size and shape than the opposite opening of the same hole (a truncated cone- shaped hole).

[0312] FIG. 7 presents a schematic illustration of two tapered holes in a mask having a local thickness, showing the diameter of the hole at the outer side (di) being smaller than the diameter of the hole at the inner side (di) of the mask.

[0313] A mask, such as the SRP-template mask, may be constructed with tapered holes. Without wishing to being bound by theory or mechanism of action, it is contemplated that tapered holes may improve one or more process parameters, such as stenciling fidelity, life-span, electrolyte hydraulics, and the like. For example, the space (void) defining a round hole may have the tapered shape of a truncated cone, and the space defining a rectangular hole may have the tapered shape of a trimmed pyramid. In some embodiments, the holes in the mask, such as the SRP-template mask, are characterized by a tapered aperture, or in other words, the hole narrows from one surface side of the foil’ s plane to the other surface. In some embodiments, the mask, such as the SRP-template mask, has an outer side that is configured to contact the starting foil, and an inner side that is configured to face the cathode, and the holes in the mask are wider at the inner side than at the outer side of the mask, namely the holes taper to the same side of the mask, which is the outer side. In some embodiments, all the holes in the mask, are wider at the inner side than at the outer side of the mask.

[0314] Without wishing to being bound by theory or mechanism of action, it is contemplated that in the electroetching process the widening of the holes outwards from the foil (and towards the cathode) assists in the flow of the electrolyte in the holes and, in particular, enhances gas bubbles removal from the foil surface, as compared to through-hole having parallel walls or tapered walls which taper towards the inner side of the mask that faces the cathode.

[0315] According to some embodiments, the diameter of the opening of the pores (opening size) of the mask, such as the SRP-template mask having a seamless repeating pattern of through-hole textural elements, as provided herein, can be as small as 1-200 pm. In some embodiments, the opening size of through-holes ranges from 10 pm to 5000 pm, or about 10-2000 pm, or about 10-1000 pm, or about 10-500 pm, or about 10-200 pm, or about 10-100 pm, or about 10-50 pm, or 20-100 pm, 30-100 pm, 40-100 pm, 50-100 pm, 60- 100 pm, 70-100 pm, 80-100 pm, 90-200 pm, 90-300 pm, 90-400 pm, or about 90-500 pm. In some embodiments, the opening size of a through-hole textural element (hole; pore) is less than about 1,000 pm, less than about 750 pm, less than about 500 pm, less than about 250 pm, less than about 100 pm, less than 90 pm, less than 80 pm, less than 70 pm, less than 60 pm, less than 50 pm, less than 40 pm, less than 30 pm, less than 20 pm, less than 15 pm, less than 10 pm, less than 9 pm, less than 8 pm, less than 7 pm, less than 6 pm, less than 5 pm, or less than 4 pm.

[0316] In some embodiments, including any of the foregoing, the pores have an opening (aperture; opening size) dimension of about 1-100 pm x about 1-100 pm, about 1-50 pm x about 1-50 pm, about 20-30 pm x about 20-30 pm, about 40 pm x 50 pm, or about 52 pm x 52 pm.

[0317] In some embodiments, the opening size of the through-hole is equal to or higher than the thickness of the mask. In further embodiments, the opening size of the mask is at least about 10 %, at least about 30 %, at least about 50 %, at least about 70 %, or at least about 100 % higher than the thickness of the mask.

[0318] The mask may have a unimodal, bimodal, trimodal, or other multimodal forms of pore (hole) size distribution. A unimodal pore size distribution may be employed when pores / textural elements of an essentially identical size are to be formed in the starting foil. A mask with a multimodal pore size distribution may be beneficial when creating a metal foil patterned with varying sizes of pores or textural elements. The mask may have a pore size distribution wherein at least 80% of the pores are within the range of 0.9-1.1 times the average pore size. Preferably, more than 90 % of the pores have a pore size within this range. Even more preferably, more than 95 % of the pores have a pore size within this range.

[0319] The average pore size and pore size distribution of the mask may be measured, inter alia, by an optical microscope or a scanning electron microscope (SEM), using suitable image analysis software.

[0320] The horizontal distance between the centers of two adjacent pores, also termed herein “pitch”, may be selected in accordance with the intended pattern of the foil as long as the adjacent pores do not coalesce. In some embodiments, the horizontal distance between the centers of two adjacent pores ranges 10-5000 pm, or 10-2,000 pm, or 50 - 2,500 pm, or 10-1000 pm, or 20-500 pm, 30-500 pm, 40-500 pm, 50-250 pm, 60-250 pm, 70-250 pm, 80-250 pm, about 100 - 200 pm, or about 60 - 100 pm. In some embodiments, the horizontal distance between the center of two through-holes (pores) in the mask is about 5 pm, 6 pm, 7 pm, 8 pm, 9 pm, 10 pm, 20 pm, 30 pm, 40 pm, 50 pm, 60 pm, 70 pm, 80 pm, 90 pm, or about 100 pm, 110 pm, 120 pm, 130 pm, 140 pm, 150 pm, 160 pm, 170 pm, 180 pm, 190 pm, 200 pm, 210 pm, 220 pm, 230 pm, 240 pm, 250 pm, 260 pm, 270 pm, 280 pm, 290 pm, 300 pm, 310 pm, 320 pm, 330 pm, 340 pm, 350 pm, 360 pm, 370 pm, 380 pm, 390 pm, or about 400 pm, 450 pm, 500 pm, 550 pm, 600 pm, 650 pm, 700 pm, 750 pm, 800 pm, 850 pm, 900 pm, 950 pm, or 1,000 pm.

[0321] Pore density depends on the size of the holes and the horizontal distance between adjacent holes. In the context of the present invention, the pore density of a mask, such as the SRP- template mask, relates to the number of through-holes per unit area. In some embodiments, the pore density relates to the ratio between mask material area and void (hole) area per unit area. According to some embodiments, the pore density ranges from 30 holes per 1 mm2(square millimeter) to 200 holes / mm2.

[0322] The uniformity of the SRP may be determined by any experimental method, such as, for example, taking photographs of different sections of the SRP-template mask or the resulting patterned foil, scanning a pre-determined area within a photograph or in different photographs, identifying and digitizing the motifs in the scanned image and measuring the size and horizontal distance of a predetermined number of motifs per scanned section, and calculating the standard deviation in motif over across sections. In embodiments where the motif / tile encompasses a single hole, the SRP uniformity related to the standard deviation between individual holes. In embodiments wherein the motif / tile encompasses more than one hole, the SRP uniformity relates to the standard deviation between motifs / tiles. In some embodiments, the standard deviation in motif overlap ranges 0-15 %. In some embodiments, the standard deviation in motif overlap is less than 15 %, less than 10 %, or less than 5 %.

[0323] Continuous subtractive manufacturing processes:

[0324] Subtractive processes of the present invention relate to the present electroetching system and process. The challenge of seamless and continuously repeating patterning was achieved by using the circumferentially closed band SRP-template mask, that was developed for continuous production mode, based on roll-to-roll architecture. The presently provided tools and methods suitable for electroetching, use electric current and the mask under certain operating conditions that remove the metal at predetermined locations in a pristine electrically-conducting foil. By choosing to perforate a pristine foil with electroetching rather than chemical etching, the present inventors achieved control over the process parameters, and thus uniform perforation patterns and high stenciling fidelity were achieved.

[0325] The roll-to-roll electroetching system provided herein may be used in methods of making a patterned metal foil, such as perforated metal foil (metallic member) or composite foil, or a metal-coated dielectric material, such as a polymer, which are suitable for producing a continuous SRP on or in a continuous pristine foil, also referred to herein as a starting / substrate foil; such methods are also referred to as continuous subtractive manufacturing methods. The present invention provides the tools and methods to produce a long, perforated foil with high and uniform porosity cheaply and rapidly, which involve the enhancement of functional porosity of thin foils, such that these perforated metallic foils provide the benefits of 3D structures (e.g., metal foams) while maintaining the benefits of uniformity, speed of production, cost of production and roll-readiness gained from continuous production methods.

[0326] The provisions of the present invention include tools and methods for perforating a preformed thin metallic foil to exhibit SRP perforation in a single subtractive manufacturing step, namely the metallic member can be afforded at any length (up to tens of kilometers long, essentially limited by the original length of the input pristine foil) by introducing perforation to the foil. The step of perforation by electroetching may be conducted under SRP conditions and uniformity requirements. In some embodiments, the subtractive manufacturing technique is electroetching, wherein an electrically-conducting foil is subjected to etching conditions through a mask that exhibits apertures arranged under SRP conditions (an SRP-template mask), causing selective removal of the etchable foil material, such as metal, through the apertures, as discussed hereinbelow. For example, a thin aluminum foil can be subjected to electroetching through an SRP-template mask having well-ordered arrangement of holes. In the context of the present invention, this well-ordered arrangement is a template for a SRP, and the mask serves as a template or a stencil for the formation of the holes in the metallic member. This step may result in a fine through-hole seamless repeating pattern in the metallic member, stencilling the arrangement of the holes in the mask.

[0327] According to some aspects and embodiments of the present invention, there is provided an electroetching process for imparting a pattern to a starting metal foil. The process comprises: feeding the foil into an electroetching unit that comprises a mask and a cathode, such that at least a contact section of the foil is disposed within the electroetching unit; contacting a contact section of the mask with the contact section of the foil, thereby forming a contact region, wherein the contact section of the mask is positioned between the cathode and the contact section of the foil; directing an electrolyte liquid composition to be tangential to the external surface of the mask along essentially an entire length of the contact section of the mask; applying current, voltage or both between the cathode and the foil while advancing the foil through the electroetching unit, thereby electroetching the foil and forming an electroetched foil and a salt of the metal, wherein the advancing is coordinated with a motion of the mask; and collecting the electroetched foil, wherein: the mask is having a form of a circumferentially closed band having an electrically insulating external surface; and said contact region is curved.

[0328] The phrase “applying current and / or voltage” as used herein is meant to also encompass applying electric power (which is a product of current and voltage), while the electroetching process may be performed at or controlled voltage, current, and / or power. A skilled artisan would further readily realize that applying current and / or voltage in an electrochemical system such as electroetching unit requires presence of an electrolyte solution between the electrodes of the system or unit to establish ionic contact therebetween.

[0329] One or more of the above steps may be performed continuously to provide an electrically- conductive foil having a seamless repeating pattern. For example, the foil may be continuously or incrementally fed into the electroetching unit and continuously (or incrementally) collected once exiting the electroetching unit. The process may further include contacting the contact section of the mask with the contact section of the foil throughout the entire continuous process and constantly applying current or voltage between the cathode and the contact section of the metal film in the presence of the electrolyte. The electrolyte may be circulated in the electroetching unit, and in particular, constantly flowing between the cathode and the contact section of the foil.

[0330] The speed by which the pristine foil is fed into the electroetching system, or collected as a patterned foil at the output roll, governs the etching time period, which is the time period that any section along the foil spends in the electroetching unit and becomes the contact region. The etching time period (and, in practice, the foil feeding speed) may be adjusted depending on the thickness of the pristine foil, the length of the contact region(s) along the workflow direction, the perforation density (indicative of the amount of foil material to be etched-away), the composition and concentration of the electrolyte solution, as well as other factors. The etching time period may be determined experimentally, and can be controlled by changing the speed of the coordinated motion of the mask and the foil and / or the power supply parameters, wherein a sufficient etching time period is not less than the minimal time for achieving the desired pore depth of the foil at the given speed and power settings. A typical etching time period ranges 1-600 sec. Alternatively, the speed by which the foil is passed through the system in the workflow direction may be adjusted based on the length of the contact region (that may depend, inter alia, on the radius of the curvature of the foil and / or the mask) to provide exposure of each axial section of the foil that enters the electroetching unit to the cathode and the electrolyte for a time period sufficient for etching (i.e., 1-600 sec). In some embodiments, the speed by which the foil is passed through the system in the workflow direction ranges from about 1 to about 500. meters per hour.

[0331] As detailed above, the present system allows directed electrolyte in a path that connects the two electrodes and the contact section of the foil and the mask, according to some embodiments. According to some embodiments, directing of the electrolyte liquid composition entails directing in a path to be tangential to the external surface of the mask along essentially an entire length of the contact section of the mask

[0332] According to some embodiments, the electrolyte liquid composition is in the form of an aqueous solution contained in a vessel. According to some embodiments, the process comprises circulating the aqueous solution between the anode and the cathode. According to some embodiments, the process comprises directing the electrolyte liquid composition to be tangential to the external surface of the mask along essentially the entire length of the contact section of the mask.

[0333] According to some embodiments, the circulation is performed under pressure. According to some embodiments, the liquid pressure is provided from a liquid pump. According to some embodiments, the circulation comprises flowing the aqueous solution using a liquid pump in a closed path, which is in contact with the anode, the cathode and the contact region, thereby achieving forced and directed flow thereto.

[0334] According to some embodiments, directing the electrolyte flow further comprises flowing between the two portions of the split cathode.

[0335] According to some embodiments, the electroetching forms an electroetched (e.g., perforated) foil and an electroetched metal salt. According to some embodiments, the starting foil comprises a metal. According to some embodiments, the metal comprises aluminum. According to some embodiments, the electroetched metal salt comprises aluminum oxide.

[0336] According to some embodiments, the process further comprises washing the mask from the salt of the metal with a washing liquid. According to some embodiments, the washing is performed using the washing unit of the system disclosed herein. According to some embodiments, the washing comprises application (e.g., rinsing) of a water stream toward a portion of the mask. The position of the portion of the mask is defined herein when relating to the washing unit. According to some embodiments, the washing comprises application (e.g., rinsing) of a water stream toward a portion of the electroetched foil. The position of the portion of the electroetched foil is defined herein when relating to the washing unit. According to some embodiments, the process includes washing both the mask and the electroetched foil.

[0337] Advancing the foil and the mask can be performed in a continuous manner or by discrete (incremental) steps. Voltage and / or current may be applied during the advancement steps and / or in the intervals between the advancement steps. When advancing foil incrementally, step duration, advancement rate and intervals between the steps may be adjusted to be compatible with the electroetching rate governed by the above-mentioned conditions, to provide a seamless pattern, if desired. For example, when the electroetching process is relatively slow and the voltage and / or current are applied in the intervals, short- duration advancement steps at a slow advancement rate with short intervals therebetween would be essentially similar to a continuous slow motion of the foil and should not impair seamlessness of the electroetched pattern. The form of the motion of the foil may be selected based on the desired final pattern and practical considerations.

[0338] The advancing may include a coordinated motion of the foil with the mask. According to some embodiments, the coordinated motion can include pressing the foil against the mask and advancing the foil, so that the mask is moving therewith (e.g., through frictional engagement).

[0339] According to some embodiments, contacting the contact section of the mask with the contact section of the foil entails pressing one of the mask and foil over the other at the contact section. According to some embodiments, advancing the starting foil entails dragging the mask at a similar rate to form a coordinated of the foil and the mask.

[0340] According to some embodiments, the process comprises preventing relative shift between the starting foil. According to some embodiments, the shift is prevented in a direction which is perpendicular to the advancement direction. According to some embodiments, the shift is prevented in a direction which is parallel to a surface of the starting foil; or both. According to some embodiments, the shift is prevented through using a crowned roller as the input roll, the outpull roll or both. According to some embodiments, the input roll is a crowned roller According to some embodiments, the output roll is a crowned roller.

[0341] It was found that parallel flow along the mask length allows to better replenish the electrolyte in the mask holes, thereby allowing etching smaller holes and / or to form etched foils with a larger open area.

[0342] The foil may be fed into the electroetching unit by an input roll and be collected as it exits the electroetching unit by an output roll. The foil that exits the electroetching unit is also termed herein “etched foil”, “patterned foil”, “porous foil”, and “perforated foil”.

[0343] Applying current and / or voltage between the cathode and the contact section of the foil may be performed by connecting the foil to a positive pole and the cathode to a negative pole of the power supply, as presented hereinabove. The voltage and / or current may be direct, constant, pulsed, stepped, or alternating, while waveform, frequency, and step duration may be adjusted based on the desired electroetching process configuration and outcome. When using pulsed voltage and / or current, polarity of the electrodes may be reversed for certain periods of time, for example, for altering electrolyte composition near the etched surface.

[0344] According to some embodiments, the process comprises applying reverse pulse current. According to some embodiments, the process comprises comprising positioning the mask between the cathode and the starting metal foil, and positioning the foil between the mask and an anode, wherein the electrolyte is in contact with the anode and with the cathode. According to some embodiments, the process comprises applying current, voltage or both between the cathode and the anode. According to some embodiments, the process comprises reversing the polarity of the anode and the cathode, and applying reverse pulse current, voltage or both between the cathode and the anode.

[0345] According to some embodiments, the reverse pulse is forming bubbles, wherein the bubbles at least partially remove the salt of the metal from the electroetched foil.

[0346] Applying current and / or voltage between the cathode and the contact section of the foil may further encompass establishing ionic contact between the foil and the cathode. The ionic contact may be established, for example, by submerging at least the contact section of the foil, the contact section of the mask, and the cathode in an electrolyte solution or by flowing the electrolyte solution at least though the part of the electroetching unit where the contact section of the foil, the contact section of the mask, and the cathode are positioned.

[0347] For example, for aluminum electroetching, an aqueous electrolyte solution can be used with 0.5-3 M NaCl and pH range between 6-8. Electroetching may be performed under a constant or pulsed voltage in the range of 3-10 V for etching time periods that range 1- 600 sec.

[0348] In some embodiments of the process provided herein, the mask is an SRP-template mask. The shape of the mask pattern and / or conditions of the electroetching process may be adjusted to provide the desired pattern on the foil, such as, inter alia, indents or through- holes.

[0349] In some embodiments, the process includes electroetching a pristine copper foil, an aluminum foil, a titanium foil, or a steel / stainless-steel foil, and in general any metal or alloy, by applying a suitable current and / or voltage. In some embodiments, the process includes electroetching an electrically-conducting composite foil containing a metal, e.g., in a form of a metal layer deposited onto a polymer film.

[0350] In some embodiments, including any of the foregoing, pristine foil is wrapped over an anode having a shape of a drum. In some of these embodiments, the drum is made of Al, Ni, Cu, Mg, Ti, steel, stainless steel, steel coated with chrome or other suitable metal that is inert in the operating conditions of the electroetching process anode.

[0351] In some embodiments, the pristine foil is wrapped over the drum that is made of a dielectric material. In certain such embodiments, the pristine foil may be electrically connected to the positive pole of the electric power supply by contacting the foil with a conductor that is electrically connected to the positive pole, such as, but not limited to, by wrapping the foil over a tension cylinder that is connected to the positive pole, before the foil gets wrapped over the drum. The drum may be made of any electrically insulating (dielectric) material that is dimensionally stable, e.g., polymers, ceramics, and polymer- coated metals. Non-limiting examples of suitable polymers include polytetrafluoroethylene (PTFE, e.g., TEFLON™) and polyaryletherketone, e.g., PEEK™.

[0352] Briefly, the continuous electroetching (subtractive manufacturing) process provided herein may be carried out, inter alia, by providing a roll of a pristine electrically conducting foil, and a circumferentially closed band mask (e.g., an SRP-template mask exhibiting a pattern of holes corresponding to the SRP) intended for etching holes in the foil, and loading (feeding) the pristine foil into an electroetching unit of an electroetching system, according to some embodiments of the present invention, essentially as presented herein. The elements of the electroetching unit may include a cathode having a curved active surface, and, optionally, a correspondingly-curve surface over-which the foil and the mask can be pressed against each other to form the contact region therebetween, which the foil is connected to or serves as an anode.

[0353] The loading of the foil into an electroetching unit is affected such that the leading end of the foil is advanced into the electroetching unit until at least a contact region of the foil is disposed within the electroetching unit, which has been fitted with the cathode and the mask. For example, in some embodiments, feeding the foil into the electroetching unit involves wrapping the foil around at least a section of the circumference of the curved surface of a conductive cylindrical mandrel, which serves as the anode in the electroetching unit, so as to form an electrically conductive contact region where the foil is in contact with the cylindrical anode.

[0354] A section of the mask is brought into contact with the contact section of the foil such that the contact section of the mask and the contact section of the foil are essentially in contact over an area having a curved shape, and such that the contact section of the mask is positioned between the cathode and the contact section of the foil. For example, the circumferentially closed band mask may be brought into contact with the section of the foil that is wrapped over the curve-shaped anode, thereby forming the curved contact region therebetween, and having the mask’s contact region disposed between the foil and the cathode. In another example, the circumferentially closed band mask is a rotatable rigid mask having a permanently stable circular shape, which encircles the cathode, and the foil that is wound over two or more tension / rotation shafts may be brought into contact with a contact section of the mask, thereby forming the curved contact region therebetween, and having the mask’s contact region disposed between the foil and the cathode.

[0355] Once the elements of the electroetching unit are brought into place and contact, the process continues by applying current and / or voltage between the cathode and the contact section of the foil in the presence of an electrolyte. For example, once the foil, the mask and other elements are brought together in the electroetching unit, optionally with additional seals and walls (plates) so as to form a flow-cell, an electrolyte is continuously flown therein, a current / voltage is continuously applied between the anode and the contact section of the pristine foil, and the relevant tension and rotation shafts are put into coordinated motion, thereby continuously electroetching the pristine foil essentially only through the holes of the mask while the foil is continuously advanced through the electroetching unit, and the contact section of the mask constantly contacts the contact section of the foil.

[0356] The process is completed once the input foil in the roll of pristine foil has been passed through the electroetching system, and the output patterned foil that exits the electroetching unit has been collected on the output roll.

[0357] FIG. 8 is a flowchart presenting the rudimentary steps of the process for continuous subtractive manufacturing (roll-to-roll configuration) of a very long patterned foil by electroetching a very long pristine foil through the holes of a mask having a repeating pattern of holes, so as to form a repeating pattern of through-holes in the foil.

[0358] According to some embodiments, the process comprises forming perforations having a mean diameter lower than 6 mm, lower than 5mm, lower than 4mm, lower than 3 mm, lower than 2mm or lower than 1mm. Each possibility represents a separate embodiment of the invention.

[0359] Continuous additive manufacturing processes:

[0360] The challenge of seamless and continuously repeating patterning was achieved by using the circumferentially closed band SRP-template mask, that was developed for continuous production mode, based on roll-to-roll architecture. The presently provided tools and methods suitable for electrodeposition, use electric current and the mask under certain operating conditions that deposit the metal at predetermined locations on an electrically- conducting foil (starting foil).

[0361] The roll-to-roll electrodeposition system provided herein may be used in methods of making a metal foil having a pattern of raised protrusions on one side of a metal foil (metallic member), a composite foil comprising more than one substance (e.g., two metals), or a metal-coated dielectric material, such as a polymer, which are suitable for producing a continuous SRP on or in a continuous pristine foil, also referred to herein as a starting foil; such methods are also referred to as continuous additive manufacturing methods. The present invention provides the tools and methods to produce a long, patterned foil with uniform, and optionally seamless surface or bulk patterns, which provide the benefits of 3D structures while maintaining the benefits of uniformity and roll-readiness gained from continuous production methods.

[0362] The provisions of the present invention include tools and methods for patterning a preformed thin metallic foil to exhibit SRP in a single additive manufacturing step, namely the metallic member can be afforded at any length (up to tens of kilometers long, essentially limited by the original length of the input starting foil) by introducing pattern to the foil. Patterning by electrodeposition may be conducted under SRP conditions and uniformity requirements. In some embodiments, the additive manufacturing technique is electrodeposition, wherein an electrically-conducting foil is subjected to an electrolyte solution containing metal ions and is held at a negative potential versus a counter electrode to effect electrodeposition of said metal through a mask that exhibits apertures arranged under SRP conditions (an SRP-template mask), causing selective growth of the electrodeposited layer within said mask apertures.

[0363] According to some aspects and embodiments of the present invention, there is provided an electrodeposition process that includes: feeding an electrically conducting starting foil into an electrodeposition unit that comprises a mask and an anode, such that at least a contact section of said foil is disposed within said electroetching unit; contacting a contact section of said mask with said contact section of said foil, thereby forming a contact region, wherein said contact section of said mask is positioned between said anode and said contact section of said foil; directing an electrolyte liquid composition to be tangential to the external surface of the mask along essentially an entire length of the contact section of the mask; applying current, voltage or both between said anode and said foil while advancing said foil through said electroetching unit, thereby electrodepositing a metal on the starting metal foil, wherein the advancing is coordinated with a motion of the mask; and collecting a patterned foil, wherein: said mask is having a form of a circumferentially closed band having an electrically insulating external surface; and said contact region is curved.

[0364] The electrodeposition subtractive process disclosed herein has similarities and shared components, steps and features with the additive electroetching process disclosed herein. The electrodeposition process thus can include any of the features described for process system, except from the specifics discussed herein with specific reference to the electrodeposition process. First, as electrodeposition and electroetching have opposite flow of electric current, the cathode and anode are reversed in function and position, therefore statements relating to the cathode in the electroetching system may be applied to the anode in the electrodeposition system and statements relating to the anode in the electroetching system may be applied to the cathode in the electrodeposition system. References to negative / positive poles may also reverse in meaning.

[0365] The starting foil may be fed into the electrodeposition unit by an input roll and be collected as it exits the electrodeposition unit by an output roll. As mentioned hereinabove, the starting foil that exits the electrodeposition unit is also termed herein “electrodeposited foil”, “patterned foil”, “patterned metallic foil”, “porous foil”, and “porous metallic foil”.

[0366] For or copper electrodeposition, an aqueous electrolyte solution can be used with 10-25 g / L of copper, 90-120 ml / L sulfuric acid, and 50-80 mg / L sodium chloride. Electrodeposition may be performed under a constant voltage at a current density of 5-10 A / dm2.

[0367] In some embodiments, the process includes electrodeposition of copper, nickel, cobalt, zinc, or any combination thereof, and in general any metal or alloy which is suitable for electrodeposition. In some embodiments, the process includes electrodeposition upon a metallic starting foil. The metal of the starting foil may be the same metal as the electrodeposited metal or a different metal. Alternatively, the process may include electrodeposition over a carbon- or graphite-based foil or a conductive polymer foil.

[0368] In some embodiments, including any of the foregoing, the starting foil is wrapped over a cathode having a shape of a drum. In some of these embodiments, the drum is made of Ti, steel, stainless steel, steel coated with chrome or other suitable metal that is inert in the operating conditions of the electrodeposition process cathode. Briefly, the continuous electrodeposition (additive manufacturing) process provided herein may be carried out, inter alia, by providing a roll of an electrically conducting starting foil, and a circumferentially closed band mask (e.g., an SRP-template mask exhibiting a pattern of holes corresponding to the SRP) intended for imparting a pattern to the starting foil, and loading (feeding) the starting foil into an electrodeposition unit of an electrodeposition system, according to some embodiments of the present invention, essentially as presented herein. The elements of the electrodeposition unit may include an anode having a curved active surface, and, optionally, a correspondingly-curve surface over-which the starting foil and the mask can be pressed against each other to form the contact region therebetween, which the starting foil is connected to or serves as a cathode. FIG. 16 is a flowchart presenting the rudimentary steps of the process for continuous electrodeposition (roll-to-roll configuration) of metal on a very long starting foil through the holes of a mask having a repeating pattern of holes, so as to form a repeating pattern of protruding structures on the surface of the starting foil.

[0369] A patterned foil:

[0370] The electrodeposition system and process provided herein, may be used to manufacture a long metallic pattered foil in industrial setting. The pattered foil is characterized by a smooth bottom side and a pattern of raised textural elements (protrusions) on the other (top) side, arranged in a seamless repeating pattern, having a three-dimensional structure that is characterized by an unlimited length, a given width, and a given thickness that is the sum of the thickness of the base foil and the height of the raised protrusions.

[0371] The raised textural elements on the top side of the base foil are attached to the base foil by being electrodeposited thereon, and arranged in a seamless repeating pattern, creating a uniform and consistent surface texture. The shape, size, and arrangement of the raised textural elements can vary depending on the specific design of the SRP-template mask. The raised textural elements are formed by electrodeposition; hence the raised textural elements are fused to the base foil. This is because the electrodeposition process involves the transfer of metal ions from an electrolyte solution to the surface of the starting foil. The metal ions are deposited on the surface as raised textural elements, and the basis of each element is bonded to the surface by metallic bonds. Metallic bonds are formed by the delocalization of electrons throughout the metal. The metal atoms lose their valence electrons and these electrons become delocalized, meaning they are not associated with any one atom but are free to move throughout the metal. The delocalized electrons are attracted to the positively charged metal ions, which creates a strong force of attraction between the atoms. Metallic bonds are responsible for the properties that make the metallic members provided herein so unique, such as their high conductivity, malleability, and ductility. The delocalized electrons allow metals to conduct electricity and heat, and they also make metals soft and easy to deform.

[0372] The strength of the bond between the raised textural elements and the base foil depends on a number of factors, including the type of metal, the concentration of the electrolyte solution, and the applied voltage. In general, the bond strength is stronger for metals with high melting points and for electrolyte solutions with high concentrations of metal ions. The applied voltage also affects the bond strength, with higher voltages resulting in stronger bonds. The fused nature of the raised textural elements to the base foil ensures that the raised textural elements are firmly attached to the surface and will not come loose, and it prevents the textural elements from corroding or being damaged by environmental factors. The fused nature of the raised textural elements to the base foil also allows the textural elements to be used in a variety of applications, such as in batteries, capacitors, electric circuitry, sensors, actuators, and microelectronics.

[0373] In some embodiments, the use of two different metals, one for the base foil and another for the raised textural affords various physical, chemical and electrical features. Phenomena that can be observed when fusing (juxtaposing) two different metals, such as in embodiments where one type of metal is electrodeposited on a different metal, include without limitation, contact potential difference, galvanic corrosion, thermoelectric effect, piezoelectric effect, and magnetic effect.

[0374] Briefly, contact potential difference is observed when two different metals are placed in contact - a potential difference is created between them over the contact interface. This potential difference is called the contact potential difference, and it is caused by the different electron affinities of the two metals. Galvanic corrosion is a type of corrosion that occurs when two different metals are placed in contact in the presence of an electrolyte - the more active metal (the one with the lower standard reduction potential) will corrode, while the less active metal will be protected. The thermoelectric effect is the production of a voltage when two different metals are placed in contact and there is a temperature difference between them, whereas the voltage generated is proportional to the temperature difference. Piezoelectricity is the ability of certain materials to generate an electric charge when they are subjected to mechanical stress. The magnetic properties of metals can be affected by the presence of other metals; for example, the addition of small amounts of cobalt or nickel to iron can make it much more magnetic.

[0375] The height of the raised textural elements would also vary depending on the electrodeposition chemical and electrical parameters, and the design of the mask. In some cases, the height of the raised elements could be relatively small, creating a subtle protruding texture on the surface (top-side) of the base foil. In other cases, the height of the raised elements could be more pronounced, creating a more prominent texture.

[0376] Thus, according to another aspect of some embodiments of the present invention, there is provided a metallic member which includes a base foil and a plurality of raised textural elements on the top-side of the base foil, wherein the raised textural elements are arranged in a seamless repeating pattern; and the metallic member has a given width and an unlimited length, or is at least 0.1 m in width and at least 0.5 m in length.

[0377] In some embodiments, the plurality of raised textural elements, or the pattern, covers a continuous, unbroken and uninterrupted area constituting at least 10 % of the area of the top-side of the base foil. In some embodiments, the SRP covers a continuous, area constituting 10-95 % and up to 100 % of the top-side of the base foil. When referring to coverage of a surface by a pattern, it is meant to consider the entire area over which the pattern is found, including the flat area between individual raised textural elements. In some embodiments, non-patterned area (i.e., the surface of the base foil that is not covered by the raised textural elements) includes a continuous strip of base foil defining the edge along the axis of the foil, or two strips along each of the two edges along the long axis of the foil, or one or two strips between the edges of the foil. Such non-pattered strips may be used for additional post-production processes and manipulation of the metallic member provided herein.

[0378] In some embodiments, the raised textural elements are formed by electrodeposition of a metal on the top-side of the base foil.

[0379] As discussed hereinabove, each of the raised textural elements inherit its base shape and dimension from the holes of the mask, since the textural element is formed by electrodepositing metal through the holes in the mask, and therefore the shape and size of the base of the structural element (the area of interface / contact between the base foil and the raised textural element) corresponds to the shape and size of the mask’s hole. According to some embodiments, the base shape of the raised textural elements have a dimension that ranges about 10-200 pm and the horizontal distance between the centers of two adjacent raised textural elements ranges about 50-250 pm.

[0380] In some embodiments, the height of the raised textural elements depends on the chemical and electrical conditions and parameters of the electrodeposition process, and the thickness of the mask. In some embodiments, the height of the raised textural elements ranges about 5-300 pm.

[0381] As discussed hereinabove, each of the base foil and the raised textural elements can be made from the same or a different metal, each selected independently from the group consisting of copper, nickel, gold, silver, iron, tin, aluminum, palladium, and any alloys and combination thereof. The base foil may be further made of an electrically conducting material such as carbon / graphite or conducting polymer. The skilled artisan will appreciate the particular selection of materials and electrodepositing parameters suitable for each type of material and any particular combination of a base material and deposited metal.

[0382] In some embodiments, the base foil is 3-100 pm thick. In some embodiments, the height of the raised textural elements ranges about 1-100 pm from the top-side of the base foil.

[0383] Additional aspects:

[0384] According to yet another aspect of some embodiments of the present invention, there is provided a roll that includes a cylindrical core and the metallic member provided herein, wound around the core.

[0385] In some embodiments, the width of the metallic member in the roll ranges at least 0.1-5 m. In some embodiments, the length of the metallic member in the roll ranges at least 0.5- 10,000 m.

[0386] According to yet another aspect of some embodiments of the present invention, there is provided a current collector that includes at least one metallic member as provided herein. As used herein, the term “current collector” (CC) refers to a substrate that conducts electrons in a sufficient manner to be used in a battery or electrochemical cell to complete an electrical circuit at the cathode and anode. The CC is typically made of a metal such as copper, aluminum or nickel. Other metals such as magnesium, tungsten, cobalt, iron, titanium, platinum, tungsten and gold, and any alloy thereof, may also be used, as well as alloys or combinations of metals, such as steel. In the context of a secondary battery, the CC in the battery cathode conducts electrons into the battery cathode from the external circuit during a discharge and conducts electrons out of the cathode into an external circuit during a charge, whereas in a battery anode, the CC conducts electrons into the battery anode from the external circuit during a charge and conducts electrons out of the battery anode into the external circuit during a discharge.

[0387] The current collector provided herein may further include contacts and contact leads, terminals and other features common and / or needed as part of a current collector, or needed for its assembly and implementation in an electric device, and these additional features, all or any selection thereof, are encompassed in the definition of a current collection, as used herein.

[0388] The advantages gained by using the metallic member provided herein as a CC, include increasing the amount of active material that can be loaded per unit area, increasing the surface area of contact between the current collector and the active material, improving electric path within the active material, and all of that while maintaining low production costs and compatibility with mass production machinery and processes.

[0389] The metallic members and CCs provided herein may contribute to a reduction of local current densities by enlarging the surface area of the CCs. Because lowering the current density at a lithium battery anode can retard the onset of dendritic growth of lithium and slow down the growth rate, the CCs provided herein may alleviate dendritic growth.

[0390] Advantageously, the member provided herein, as well as the current collector comprising or consisting of the same, can be implemented in electrode production in the form of continuous rolls of feed foil that is being fed into the active material coating devices, later to be cut into individual electrodes.

[0391] Thus, according to as aspect of some embodiments of the present invention, there is provided an electrode, e.g., in the context of a battery or a capacitor, that includes at least one current collector, and an active electrode material (a.k.a., coating material) disposed on the CC, wherein the current collector includes at least one, or consists of the metallic member provided herein. Herein throughout, the term “electrode” refers to both anodes and cathode, unless stated otherwise explicitly.

[0392] Electrode coating is a significant part of battery manufacturing process, with a large contribution to the final micro structure and thus pertinent to the functioning of the resulting electrode. According to embodiments of the present invention, coating of the metallic member provided herein can be performed via various routes, whereas the coater device may be a draw down coater, which is commonly used in research labs to produce small coatings, or for larger, industrial applications, a roll-to-roll (a.k.a., R2R or reel-to- reel) coater, for which the presently disclosed member is particularly suitable. In a roll- to-roll setup, the geometry of the coater, used to coat the metallic member according to some embodiments of the present invention, can be doctor blade (a fine blade set at a fixed gap from the CC), comma bar (a comma shaped geometry with a curved leading edge), slot die (coating material is extruded out of a slot onto the CC), “knife-over-roll” (coating material is dispensed to the CC, which then passes through a knife and roller), “reverse roll”, “Meyer rod” (wherein a roller applies the coating material to the CC, and then a Meyer bar meters out the correct amount), as these methods and devices are known in the art. The coating may be applied while the CC is supported by a roller, or it can also be applied to an unsupported CC under tension, which is known as tensioned web coating. Other electrode coating processes known in the art may be used to coat a current collector, set forth herein.

[0393] Thus, according to some embodiments of the present invention, the electrode is produced by any known roll-to-roll (R2R) process, using a roll of the metallic member provided herein.

[0394] In view of the forgoing, there is provided a cell or a battery, that includes at least one electrode, wherein the electrode comprises at least one metallic member as provided herein, or wherein the electrode comprises a current collector that includes at least one, or consists of the metallic member provided herein. It is noted herein that while a cell is a single unit of device that converts chemical energy into electrical energy, and a battery may include a collection of cells that converts chemical energy into electrical energy, the terms “cell” and “battery” are used herein interchangeably.

[0395] Correspondingly, there is provided an electric device that includes the cell, an array of cells, the battery or an array of batteries, as provided herein.

[0396] In some embodiments, the cell or the battery includes at least one electrode that includes at least one current collector, wherein the CC is a metallic member as described herein. The electric devices which are contemplated within the scope of the present invention, include any electric device that can use the cell or the battery provided herein as a main, auxiliary or minor source of energy. Alternatively, an electric device is one that includes at least one battery according to the present invention, wherein the device uses the electricity stored in the battery as its power source.

[0397] Examples of electric devices include, without limitation, an electric vehicle for transportation in air, land, water and / or space, a smartphone, a laptop computer, a portable media player, a power tool, a toy, a heating device, a colling device, an article for illumination (e.g., flashlight), and the likes.

[0398] The battery according to the various embodiments of the present invention may further be present within a power storage and / or generation device or system,

[0399] It is expected that during the life of a patent maturing from this application many relevant tools and methods for continuous electrodeposition of electrically conducting foils will be developed and the scope of the phrase "tools and methods for continuous electrodeposition of electrically conducting foils" is intended to include all such new technologies a priori.

[0400] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

[0401] As used herein the term “about” refers to ± 10 %. For example, the term “about 100 pm” encompasses the value 100 pm, as well as the values 90 pm, 91 pm, 92 pm, 93 pm, 94 pm, 95 pm, 96 pm, 97 pm, 98 pm, 98 pm, 99 pm, 100 pm, 101 pm, 102 pm, 103 pm, 104 pm, 105 pm, 106 pm, 107 pm, 108 pm, 109 pm, and 110 pm.

[0402] The terms "comprises", "comprising", "includes", "including", “having” and their conjugates mean "including but not limited to".

[0403] The term “consisting of’ means “including and limited to”.

[0404] The term "consisting essentially of" means that the composition, method or structure may include additional ingredients, steps and / or parts, but only if the additional ingredients, steps and / or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure.

[0405] As used herein, the phrase “selected from the group consisting of’ includes all members of the recited group, each member of the recited group, and all possible combinations. For example, selected from the group consisting of A, B, and C, includes A, only, as well as B, only, as well as C, only, as well as A and B, as well as A and C, as well as B and C, and as well as A, B, and C.

[0406] As used herein, the phrases "substantially devoid of" and / or "essentially devoid of" in the context of a certain substance, refer to a composition that is totally devoid of this substance or includes less than about 5, 1, 0.5 or 0.1 percent of the substance by total weight or volume of the composition. Alternatively, the phrases "substantially devoid of" and / or "essentially devoid of" in the context of a process, a method, a property or a characteristic, refer to a process, a composition, a structure or an article that is totally devoid of a certain process / method step, or a certain property or a certain characteristic, or a process / method wherein the certain process / method step is affected at less than about 5, 1, 0.5 or 0.1 percent compared to a given standard process / method, or property or a characteristic characterized by less than about 5, 1, 0.5 or 0.1 percent of the property or characteristic, compared to a given standard.

[0407] When applied to an original property, or a desired property, or an afforded property of an object or a composition, the term “substantially maintaining”, as used herein, means that the property has not change by more than 20 %, 10 % or more than 5 % in the processed object or composition.

[0408] The term “exemplary” is used herein to mean “serving as an example, instance or illustration”. Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and / or to exclude the incorporation of features from other embodiments.

[0409] The words “optionally” or “alternatively” are used herein to mean “is provided in some embodiments and not provided in other embodiments”. Any particular embodiment of the invention may include a plurality of “optional” features unless such features conflict.

[0410] As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a compound" or "at least one compound" may include a plurality of compounds, including mixtures thereof. Throughout this application, various embodiments of this invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

[0411] Whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range. The phrases “ranging / ranges between” a first indicate number and a second indicate number and “ranging / ranges from” a first indicate number “to” a second indicate number are used herein interchangeably and are meant to include the first and second indicated numbers and all the fractional and integral numerals therebetween.

[0412] As used herein the terms “process” and "method" refer to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of the chemical, material, mechanical, computational and digital arts.

[0413] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and / or materials are described below. In case of conflict, the patent specification, including definitions, will prevail. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

[0414] Various embodiments and aspects of the present invention as delineated hereinabove and as claimed in the claims section below find experimental support in the following examples. EXAMPLES

[0415] Reference is now made to the following examples, which together with the above descriptions, illustrate some embodiments of the invention in a non-limiting fashion.

[0416] EXAMPLE 1

[0417] Foil perforation system

[0418] The roll-to-roll electroetching system used in this example included a foil advancing mechanism that included an unwind shaft (an input roll), a rewind shaft (an output roll), and an electroetching unit. The electroetching unit included a center cylinder 15 cm in diameter, made of stainless steel and coated with TEFLON™, corresponding to cylindrical mandrel 24 in FIGs. 2A-B, a roll corresponding to tension cylinder 26 in FIGs. 2A-B and connected to the positive pole of a power supply, a concave cathode corresponding to cathode 23 in FIGs. 2A-B, wherein the curvature of the cathode matches the curvature of the center cylinder inversely so as to maintain a constant distance between the cathode and the center cylinder.

[0419] The electroetching unit further included a mask, acting as an SRP-template mask, and corresponding to mask 21 in FIGs. 2A-B, tensioned by two tension shafts, corresponding to tension shafts 22a and 22b in FIGs. 2A-B, and surrounding the cathode, wherein the mask exhibited a pattern of round holes, each 100 pm in diameter and arranged in a hexagonal 2D packing with hole centers distance of 150 pm.

[0420] The system further included an electrolyte flow and circulation mechanism, a perforated foil cleaning station, various guiding idler rollers, tension and rotation shafts, and a CCU, all of which are not shown in the figures. The electrolyte was an aqueous solution of NaCl 3M containing a dispersant dissolved in ethanol.

[0421] The mask was made of a 45 pm thick and 94.2 cm long Kapton® film (polyimide by DuPont) 20 cm wide, that was used to form a closed band, and was patterned with the SRP as a closed band using a computer guided laser beam. FIG. 9 is a photograph of the exemplary mask used in this example, exhibiting an SRP of round holes of 100 pm in diameter spaced apart by 150 pm and arranged in a hexagonal packing. A roll of pristine (unperforated) aluminum foil, 19 cm wide, 13 pm thick and 300 meters long was loaded on the system and used as the input roll for the process. The lead end of the foil was pulled over and wrapped around a portion of the center cylinder facing the cathode, making sure no wrinkles form in the foil. The foil was further guided through the cleaning station of the system and from there to the rewind shaft (output roll).

[0422] The mechanism tensioning the SRP-template mask was moved towards the center cylinder so as to press the contact region of the mask against the contact region of the foil, thereby creating the perforation zone (see, dashed rectangle in FIGs. 2A-B).

[0423] The cathode was positioned closer to the perforation zone, such that a gap of 0.2 mm was formed between the tensioned SRP-template mask and the concave surface of the cathode (see, for example, FIG. 2B).

[0424] The electrolyte circulation was activated, filling the perforation zone with the electrolyte (i.e., exposing the contact region thereto), and foil advancing mechanism was put into motion, driving the foil and the mask in a coordinated motion.

[0425] A current of 280 Amp under potential of 10 V was applied on the electrodes, and the electroetching process took place within the perforation zone, stenciling the SRP of the mask onto / into the pristine foil, essentially as described hereinabove, according to some embodiments of the present invention.

[0426] The resulting perforated aluminum foil was collected on the rewind shaft.

[0427] FIG. 10 is a photograph of the perforated aluminum foil resulting from the herein- provided process, exhibiting an SRP of round through-holes of 100 pm in diameter spaced apart by 150 pm.

[0428] EXAMPLE 2

[0429] Electrodeposition system

[0430] The roll-to-roll electrodeposition system used in this example included a foil advancing mechanism that included an unwind shaft (an input roll), a rewind shaft (an output roll), and an electrodeposition unit. The electrodeposition unit included a center cylinder 115 cm in diameter, made of stainless steel and coated with TEFLON™, corresponding to cylindrical mandrel 124 in FIGs. 12A-B, a roll corresponding to tension cylinder 126 in FIGs. 12A-B and connected to the negative pole of a power supply, a concave anode corresponding to anode 123 in FIGs. 12A-B, wherein the curvature of the anode matches the curvature of the center cylinder inversely so as to maintain a constant distance between the anode and the center cylinder.

[0431] The electrodeposition unit further included a mask, acting as an SRP-template mask, and corresponding to mask 121 in FIGs. 12A-B, tensioned by two tension shafts, corresponding to tension shafts 122a and 122b in FIGs. 12A-B, and surrounding the anode, wherein the mask exhibited a pattern of round holes, each 100 pm in diameter and arranged in a hexagonal 2D packing with hole centers distance of 150 pm.

[0432] The system further included an electrolyte flow and circulation mechanism, a patterned foil cleaning station, various guiding idler rollers, tension and rotation shafts, and a CCU, all of which are not shown in the figures. The electrolyte contained copper sulfate 75 g / 1 and H2SO4 100 g / 1.

[0433] The mask was made of a 45 pm thick and 94.2 cm long Kapton® film (polyimide by DuPont) 20 cm wide, that was used to form a closed band, and was patterned with the SRP as a closed band using a computer guided laser beam.

[0434] A roll of 30 pm thick starting copper foil was loaded on the system and used as the input roll for the process. The lead end of the starting foil was pulled over and wrapped around a portion of the center cylinder facing the anode, making sure no wrinkles form in the starting foil. The starting foil was collected on the rewind shaft (output roll).

[0435] The mechanism tensioning the SRP-template mask was moved towards the center cylinder so as to press the contact region of the mask against the contact region of the foil, thereby creating the electrodeposition zone (see, dashed rectangle in FIGs. 2A-B).

[0436] The anode was positioned closer to the electrodeposition zone, such that a gap of 1-2 mm was formed between the tensioned SRP-template mask and the concave surface of the anode (see, for example, FIG. 2B).

[0437] The electrolyte circulation was activated, filling the electrodeposition zone with the electrolyte (i.e., exposing the contact region thereto), and foil advancing mechanism was put into motion, driving the starting foil and the mask in a coordinated motion.

[0438] A direct current of 6-8 Amp / dm2was applied on the electrodes, and the electrodeposition process took place within the electrodeposition zone, inversely stenciling the SRP of the mask onto / into the starting foil, essentially as described hereinabove, according to some embodiments of the present invention. The resulting patterned foil was collected on the rewind shaft. Microscope images of the obtained patterned foil are presented in FIGs. 17A-B.

[0439] FIGs. 17A-B present microscope images of an exemplary copper foil including copper textural elements electrodeposited on its surface, resulting from the herein-provided process, the elements being cone-shape textural elements of approximately 10-20 pm height and 100 pm base diameter spaced apart by about 150 pm

[0440] Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

[0441] It is the intent of the applicant(s) that all publications, patents and patent applications referred to in this specification are to be incorporated in their entirety by reference into the specification, as if each individual publication, patent or patent application was specifically and individually noted when referenced that it is to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting. In addition, any priority document(s) of this application is / are hereby incorporated herein by reference in its / their entirety.

Claims

CLAIMS:

1. A roll-to-roll foil patterning system, comprising: an electropatterning unit, configured to transform a starting foil into a patterned foil upon application of electric current and / or voltage; an input roll configured to feed said starting foil into said electropatterning unit; and an output roll configured to collect said patterned foil, wherein said electropatterning unit comprises: an electrode an elastic mask; two or more shafts, which hold said mask under tension; a vessel for holding and / or circulating a liquid electrolyte composition; a fluid transportation unit in fluid flow connection with the vessel; and a power supply, wherein said starting foil and said patterned foil is electrically conducting; wherein said mask has a circumferentially closed band form, having an external surface that is electrically insulating, wherein the mask comprises a contact section positioned to contact a corresponding contact section of said starting foil such that said contact section of said mask has a curved shape, which conforms to a curvature of said contact section of said starting foil, wherein said contact section of said mask is positioned between said electrode and said contact section of said starting foil; wherein the fluid transportation unit is configured to direct a flow of the electrolyte composition supplied by the vessel to be tangential to the external surface of the mask along essentially an entire length of the contact portion of the mask; wherein upon feeding said starting foil by the input roll and / or collecting said patterned foil by the output roll, said mask and said starting foil are configured for coordinated motion while said starting foil is in contact with said mask; and said power supply is configured to apply voltage and / or current between said electrode and said contact section of said starting foil in the presence of said electrolyte composition.

2. The system of claim 1, wherein said electropatteming unit comprises a washing unit, connectable to a washing liquid source, wherein the washing unit comprises at leastone nozzle facing a portion of the elastic mask and configured to rinse the portion of the elastic mask with a washing liquid.

3. The system of claim 2, wherein the liquid comprises water, and wherein the washing unit comprises two nozzles, and is configured to wash the portion of the mask with pressurized water.

4. The system of any one of claims 1-3, wherein the fluid transportation unit is positioned between the electrode and the mask within the contact region.

5. The system of any one of claims 1-4, wherein the electrode is divided into two essentially equal sections and the fluid transportation unit is positioned between said two sections facing the mask.

6. The system of any one of claims 1-5, further comprising an ultrasonic cleaning device comprising an ultrasonic transducer, which is facing the foil when wrapped around the input roll and output role, and configured to transmit ultrasonic wave thereto.

7. The system of any one of claims 1-6, further comprising a counter electrode, which is positioned adjacent to the contact section.

8. The system of claim 7, further comprising a liquid pump, configured to circulate the electrolyte composition, in a flow path between the electrode and the counter electrode.

9. The system of claim 8, further comprising a filter positioned within the flow path and configured to filter solid particles from the electrolyte composition.

10. The system of any one of claims 1-9, wherein the mask comprises a hydrophilic material; the mask is composed of a polymer or a polymer-coated metal; or both.

11. The system of any one of claims 1-10, wherein the mask comprises a polyamide film.

12. The system of any one of claims 1-11, wherein upon feeding said starting foil by the input roll and / or collecting said patterned foil by the output roll, said starting foil is pressed against said mask, wherein the input roll, output roll or both are configured to transition the starting foil in a direction from the input roll to the output roll, wherein the pressing and the transition of the starting foil are dragging the mask, so that the starting foil is configured for coordinated motion with said mask.

13. The system of any one of claims 1-12, wherein the at least one of the input roll and output roll is a crowned roller, configured to maintain alignment of the starting role with the mask in a lateral direction perpendicular to a direction of motion of the mask and the staring foil.

14. The system of any one of claims 1-13, wherein said electrode has a curved active surface having a curvature that conforms to a curvature of said contact section of said starting foil.

15. The system of any one of claims 1-14, wherein said electropatterning unit comprises an element having a curved surface that is configured to contact said starting foil on a first side of said contact section of said starting foil, and said contact section of said mask is configured to contact said starting foil on a second side of said contact section of said starting foil.

16. The system of claim 15, wherein said mask is configured to move towards said element prior to effecting an electropatterning process, thereby forming an electropatterning zone between said contact section of said starting foil and said electrode.

17. The system of any one of claims 14-16, wherein said curved surface forms a part of a lateral surface of a rotatable cylinder or of a surface of an endless belt conveyor.

18. The system of claim 17, wherein the electrode is a cathode, wherein said curved surface is electrically insulating, and said starting foil is connected to a positive pole of said power supply via an electrically conducting shaft that is positioned outside said electropatterning zone.

19. The system of claim 17, wherein the electrode is an anode, wherein said curved surface is electrically insulating, and said starting foil is connected to a negative pole of said power supply via an electrically conducting shaft that is positioned outside said electropatterning zone.

20. The system of any one of claim 15-19, wherein the mask is configured to move towards said element prior to effecting an electropatterning process, thereby forming an electropatterning zone between the contact section of the starting foil and the electrode.

21. The system of any one of claim 15-20, wherein the curved surface is electrically conductive, and the starting is be connected to a pole of the power supply via said curved surface.

22. The system of any one of claims 1-21, wherein said mask is configured to move towards said starting foil, thereby forming an electropatterning zone between said contact section of said starting foil and said electrode.

23. The system of any one of claims 1-22, wherein said mask encircles said electrode.

24. The system of any one of claims 1-23, further comprising a computerized control unit.

25. The system of any one of claims 1-24, which is a roll-to-roll foil electroetching system, wherein: the electropatterning unit is a an electroetching unit configured to transform the starting foil into an electroetched foil upon the application of electric current and / or voltage, and the electrode is a cathode.

26. The system of claim 25, wherein said mask is an SRP-template mask, exhibiting a seamless repeating patten (SRP) of through-holes, wherein said through-holes have an opening dimension of about 10-2,000 pm and wherein the through-holes have a pitch of about 50-2,500 pm.

27. The system of any one of claims 25-26, wherein said mask has a thickness ranging from about 5 pm to about 100 pm.

28. The system of any one of claims 1-24, which is a roll-to-roll foil electrodeposition system, wherein: the electropatterning unit is an electrodeposition unit configured to transform the starting metal foil into a foil patterned by electrochemically deposited metal upon the application of electric current and / or voltage, and the electrode is an anode.

29. The system of claim 28, wherein said mask is an SRP-template mask, exhibiting a seamless repeating patten (SRP) of through-holes, wherein said through-holes have an opening dimension of about 10-2,000 pm and wherein a horizontal distance between the centers of two adjacent through-holes ranges about 50 - 2,500 pm.

30. The system of any one of claims 28-29, wherein said mask has a thickness ranging from about 20 pm to about 300 pm.

31. An electroetching process for imparting a pattern to a starting metal foil, the process comprising:feeding the foil into an electroetching unit that comprises a mask and a cathode, such that at least a contact section of said foil is disposed within said electroetching unit; contacting a contact section of said mask with said contact section of said foil, thereby forming a contact region, wherein said contact section of said mask is positioned between said cathode and said contact section of said foil; directing an electrolyte liquid composition to be tangential to the external surface of the mask along essentially an entire length of the contact section of the mask; applying current, voltage or both between said cathode and said foil while advancing said foil through said electroetching unit, thereby electroetching the foil and forming an electroetched foil and a salt of the metal, wherein the advancing is coordinated with a motion of the mask; and collecting the electroetched foil, wherein: said mask is having a form of a circumferentially closed band having an electrically insulating external surface; and said contact region is curved.

32. The process of claim 31 further comprising washing the mask from the salt of the metal with a washing liquid.

33. The process of any one of claims 27-32, wherein said applying current and / or voltage is affected in the presence of the electrolyte liquid composition, which comprises an electrolyte, wherein the electrolyte is supplied to an electroetching zone formed between said cathode and said contact region.

34. The process of claim 33, comprising positioning the mask between the cathode and the starting metal foil, and positioning the foil between the mask and an anode, wherein the electrolyte is in contact with the anode and with the cathode; applying current, voltage or both between said cathode and said anode; reversing the polarity of the anode and the cathode; and applying reverse pulse current, voltage or both between said cathode and said anode, thereby at least partially removing the salt of the metal from the electroetched foil and / or from the contact section of the mask.

35. The process of claim 34, wherein the electrolyte liquid composition is in the form of an aqueous solution contained in a vessel, and the process comprises: circulating the aqueous solution between the anode and the cathode or between the foil and the cathode; and directing the electrolyte liquid composition to be tangential to the external surface of the mask along essentially the entire length of the contact section of the mask.

36. The process of claim 35, wherein the circulation is performed under pressure, and comprises flowing the aqueous solution using a liquid pump in a closed path, which is in contact with the any one of the anode and the foil, the cathode and the contact region, thereby achieving forced and directed flow thereto.

37. The process of any one of claims 31-36, wherein the foil is an aluminum foil.

38. The process of any one of claims 31-37, wherein the mask is configured to move towards said element prior to effecting an electroetching process, thereby forming an electroetching zone between the contact section of the starting foil and the cathode.

39. The process of any one of claims 31-38, wherein: contacting the contact section of the mask with the contact section of the foil entails pressing one of the mask and foil over the other at the contact section, wherein advancing the starting foil entails dragging the mask at a similar rate to form a coordinated motion of the foil and the mask; the process comprises preventing relative shift between the starting foil and the mask in a direction which is perpendicular to the advancement direction and parallel to a surface of the starting foil; or both.

40. The process of any one of claims 31-39, wherein the starting metal has thickness in the range of 5pm to 100pm.

41. The process of any one of claims 31-40, wherein electroetching the foil entails forming the salt of the metal and the electroetched foil having a plurality of etched perforations, wherein the plurality of etched perforations has a mean diameter of no more than 100pm; an open area of the plurality of perforations in the electroetched foil of at least 15% based of the total area of the electroetched foil; or both.

42. The process of any one of claims 31-3841 wherein said mask is elastic, and wherein the process comprises: tensioning the mask between two or more shafts; and contacting the contact section of the foil with a lateral surface of a cylinder or with a surface of an endless belt conveyer.

43. The process of any one of claims 31-42, wherein said feeding is affected from a feed roll; said collecting is affected onto an output roll; or both.

44. The process of any one of claims 31-43, further comprising, prior to said collecting, rinsing said electroetched foil.

45. An electrodeposition process comprising: feeding an electrically conducting starting foil into an electrodeposition unit that comprises a mask and an anode, such that at least a contact section of said foil is disposed within said electroetching unit; contacting a contact section of said mask with said contact section of said foil, thereby forming a contact region, wherein said contact section of said mask is positioned between said anode and said contact section of said foil; applying current, voltage or both between said anode and said foil while advancing said foil through said electroetching unit, thereby electrodepositing a metal on the starting metal foil, wherein the advancing is coordinated with a motion of the mask; and collecting a patterned foil, wherein: said mask is having a form of a circumferentially closed band having an electrically insulating external surface; and said contact region is curved.

46. The process of claim 45, further comprising directing an electrolyte liquid composition to be tangential to the external surface of the mask along essentially an entire length of the contact section of the mask;47. A metallic member comprising a base foil and a plurality of raised textural elements on a surface of said base foil, wherein: said plurality of raised textural elements is arranged in a seamless repeating pattern.

48. The metallic member of claim 47, which is at least 0.1 m in width and at least 0.5 m in length.

49. The metallic member of any one of claims 47-48, which is prepared by the process of claim 42.

50. A roll comprising a cylindrical core and the metallic member of any one of claims 47-48, wound around said core.

51. A current collector, comprising at least one metallic member according to any one of claims 47-48.

52. An electrode comprising the current collector according to claim 51.

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