Method for etching conductive features, and related devices and systems

Abstract

To provide a method for reducing the uncontrolled spread / translation of a deposited liquid etching mask ink on a surface of a substrate, when non-impact printing is used to prepare an etching mask.SOLUTION: A method of making a device patterned with one or more electrically conductive features includes: depositing a conductive material layer over an electrically insulating surface of a substrate; depositing an anti-corrosive material layer over the conductive material layer; and depositing an etch-resist material layer over the anti-corrosive material layer. The anti-corrosive material layer forms a bi-component etch mask in a pattern resulting in covered portions of the conductive material layer and exposed portions of the conductive material layer, the covered portions being positioned at locations corresponding to one or more conductive features of the device. A wet-etch process is performed to remove the exposed portions of the conductive material layer from the electrically insulating substrate, and the bi-component etch mask is removed to expose the remaining conductive material.SELECTED DRAWING: Figure 19

Description

Technical Field

[0001] Introduction The manufacture of various electronic devices and electronic components requires the fabrication of pattern layers on a substrate. For example, microchips, printed circuit boards, solar cells, electronic displays (such as liquid crystal displays, organic light emitting diode displays, and quantum dot electroluminescent displays), and various other electrical or optical devices and components may be composed of a number of overlapping pattern layers of different materials supported by a substrate. The manufacture of one such pattern layer on a substrate may be carried out by depositing an unpatterned layer of material on the substrate, preparing an etching resist mask on such a layer, and performing an etching process to remove the portions of the layer not covered by the etching resist mask, and thus forming a pattern layer on the substrate.

Background Art

[0002] In one illustrative example that can be used to manufacture, for example, a printed circuit board (PCB) or other electronic components, an electrically conductive metal layer is deposited on the electrically insulating surface of the substrate (i.e., an electrically conductive layer is formed on the electrically insulating surface of the substrate), an etching resist mask is deposited (or formed) on the conductive layer, an etching process is performed to remove the portions of the conductive layer not covered by the etching resist mask, and thus a patterned conductive layer is formed on the electrically insulating surface of the substrate. Such a patterned conductive layer may include one or more conductive features of conductive material, such as lines, circles, squares, and other shapes, on the electrically insulating surface of the substrate. In certain cases, the etching process used to form such a patterned conductive layer may be a wet etching process, in which a liquid etching material interacts with the conductive layer such that the conductive layer is removed from the electrically insulating surface of the substrate. Such a wet etching process may be, for example, a wet "chemical" etching process.

[0003] A common feature in wet etching is "undercutting," which, in typical cases of etching conductive layers, refers to the removal of conductive layer material beneath the etching mask. Such undercutting can reduce the conductivity of the conductive layer by reducing the feature width in the direction perpendicular to the current flow relative to the corresponding width of the etching mask. As a result, the conductivity may drop below the desired level. Such a reduction in conductivity due to undercutting can be particularly pronounced for relatively small feature widths, for example, those narrower than about 60 μm. This undercutting phenomenon can also impart a sloped or non-planar "sidewall" to the conductive feature. As used herein, "sidewall" refers to the lateral surface of a feature, such as the side wall of the feature extending downward from the top of the feature adjacent to the etching mask to the bottom of the feature adjacent to the substrate. In some cases, a feature associated with such undercutting may have a sloped or non-planar sidewall such that the width near the top of the feature (closer to the etching mask) is smaller than the width near the bottom of the feature (closer to the substrate). Since a certain minimum feature width above a feature is considered desirable, for example, to achieve a desired conductivity or a desired electrical frequency response, such an undercut may impose a lower limit on at least one of the minimum feature width or the minimum spacing between features, thereby limiting the density of features that can be provided to the substrate.

[0004] Undercuts are considered undesirable in applications other than patterning conductive metal wires in PCB manufacturing. For example, similar concerns already mentioned regarding PCBs may apply to other applications that utilize metal wires for the purpose of transmitting current and / or electrical signals, such as in the manufacture of microchips, electronic displays, or solar cells. In another example, other concerns may apply to applications that utilize pattern layers, non-metallic layers, such as optical coatings or insulating layers, in the manufacture of electronic or optical devices or components where substantially vertical sidewalls are desirable.

[0005] When forming pattern layers on a substrate for the purpose of manufacturing electronic and / or optical devices or electronic and / or optical components, there is a need for improved techniques to mitigate (e.g., reduce or eliminate) feature undercuts formed using wet etching processes.

[0006] In conventional processing, the etching mask described above is formed by depositing a blanket coating of a photosensitive material (often a UV-sensitive material) onto the substrate, which is then converted into an etching mask by exposure and subsequent processing according to the pattern. Such subsequent processing typically involves the removal of the photosensitive material (e.g., during the developing step) so that the etching mask pattern is formed on the substrate. In many cases, but not limited to, when an etching mask is used to pattern a metal layer of a PCB, the etching mask covers less than 50% of the substrate surface, and the removed photosensitive material is discarded as waste. In many cases, the removal of photosensitive materials requires cleaning the substrate in a liquid (e.g., developer), and the liquid used for such cleaning is discarded as waste. Often, but not limited to, when etching masks are used to pattern the metal layers of a PCB, the photosensitive material is prepared on a carrier sheet and then transferred from the carrier sheet to the substrate via lamination, and after such transfer, the carrier sheet is discarded as waste. When manufacturing electronic and / or optical devices and / or components, it is often desirable to reduce waste. One method for reducing such waste is to directly attach the etching mask to the substrate in the desired pattern using non-impact printing (e.g., inkjet printing) so that a liquid etching mask ink is delivered onto the substrate in the desired pattern, and then the liquid coating is processed (e.g., via drying and / or baking) to form the finished etching mask. However, inks ejected by such non-impact printing methods are typically not adequately absorbed on the surface of substrates used in the manufacture of optical and / or electrical components and / or devices. Such inks can spread and / or translate on such surfaces in an uncontrolled manner, potentially leading to phenomena such as clustering, aggregation, and dot gain. As a result, etching masks obtained from such non-impact printing processes may exhibit reduced resolution, lack of detail, inconsistent patterned line widths, insufficient line edge smoothness, connections between features that should be separated, and breaks in features that should be continuous. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] As described above, when non-impact printing is used to prepare etching masks, it is required to mitigate (e.g., reduce or eliminate) such uncontrolled spreading and / or translation of the deposited liquid etching mask ink on the substrate surface. [Means for solving the problem]

[0008] Abstract In one exemplary aspect of the present disclosure, a method for fabricating a patterned device with one or more electrically conductive features includes depositing a conductive material layer on an electrically insulating surface of a substrate, depositing a corrosion-resistant material layer on the conductive material layer, and depositing an etching resist material layer on the corrosion-resistant material layer. In the deposition of the etching resist material layer on the corrosion-resistant material layer, the etching resist material layer and the corrosion-resistant material layer form a two-component etching mask in a pattern that results in covered portions of the conductive material layer and exposed portions of the conductive material layer, the covered portions being positioned at locations corresponding to one or more electrically conductive features of the device. A wet etching process is performed to remove the exposed portions of the electrically insulating substrate, the two-component etching mask is removed, and the remaining conductive material in the covered portions of the conductive material layer is exposed, thereby forming one or more electrically conductive features of the device.

[0009] In another exemplary embodiment of the present disclosure, an apparatus for fabricating a patterned device with electrically conductive features includes a first deposition module configured to deposit a corrosion-resistant material layer on a conductive material layer on an electrically insulating surface of a substrate; a second deposition module configured to deposit an etching resist material layer on the corrosion-resistant material; and a wet etching module configured to etch the conductive material layer of the substrate.

[0010] In yet another exemplary aspect of the present disclosure, a device patterned with an electrically conductive feature includes a substrate having an electrically insulating surface and a conductive feature deposited on the electrically insulating surface. The conductive feature includes a height (c) measured perpendicular to the electrically insulating surface, a first width (a) measured on the electrically insulating surface, and a second width (b) measured at the end of the conductive feature opposite the electrically insulating surface along the height (c) of the conductive feature. The value obtained by dividing half the difference between ) and the height (c) is at least 2 (i.e., [ab] / c ≥ 2).

[0011] In yet another exemplary embodiment of the present disclosure, the method includes applying a first liquid composition containing a first reactive component to a metal surface to form a primer layer, and printing a second liquid composition containing a second reactive component onto the primer layer in an image by a non-impact printing process to generate an etching mask according to a predetermined pattern. When droplets of the second liquid composition come into contact with the primer layer, the second reactive component undergoes a chemical reaction with the first reactive component to immobilize the droplets.

[0012] Additional purposes, features, and / or other advantages are partially stated in the following description, partially revealed therefrom, or can be learned through the implementation of this disclosure and / or claims. At least some of these purposes and advantages can be realized and achieved by the elements and combinations specifically indicated in the appended claims.

[0013] Both the above general description and the following detailed description are illustrative and descriptive only, and do not limit the scope of the claims; rather, the claims should cover the entire scope of those claims, including their equivalents. [Brief explanation of the drawing]

[0014] [Figure 1A] Figure 1A shows cross-sectional and plan views of a device that has undergone a conventional process for forming a pattern layer on a substrate. [Figure 1B] Figure 1B shows cross-sectional and plan views of a device that has undergone a conventional process for forming a pattern layer on a substrate. [Figure 1C] Figure 1C shows cross-sectional and plan views of a device that has undergone a conventional process for forming a pattern layer on a substrate. [Figure 1D] Figure 1D shows cross-sectional and plan views of a device that has undergone a conventional process for forming a pattern layer on a substrate. [Figure 2A]FIG. 2A shows a cross-sectional view and a plan view of a device that has undergone another conventional process for forming a pattern layer on a substrate. [Figure 2B] FIG. 2B shows a cross-sectional view and a plan view of a device that has undergone another conventional process for forming a pattern layer on a substrate. [Figure 2C] FIG. 2C shows a cross-sectional view and a plan view of a device that has undergone another conventional process for forming a pattern layer on a substrate. [Figure 3A] FIG. 3A shows a cross-sectional view and a plan view of a device that has undergone another conventional process for forming a pattern layer on a substrate. [Figure 3B] FIG. 3B shows a cross-sectional view and a plan view of a device that has undergone another conventional process for forming a pattern layer on a substrate. [Figure 4A] FIG. 4A shows a cross-sectional view and a plan view of a device that has undergone another conventional process for forming a pattern layer on a substrate. [Figure 4B] FIG. 4B shows a cross-sectional view and a plan view of a device that has undergone another conventional process for forming a pattern layer on a substrate. [Figure 4C] FIG. 4C shows a cross-sectional view and a plan view of a device that has undergone another conventional process for forming a pattern layer on a substrate. [Figure 5A] FIG. 5A shows a cross-sectional view, a plan view, and a perspective view of a device that has undergone another conventional process for forming a pattern layer on a substrate. [Figure 5B] FIG. 5B shows a cross-sectional view, a plan view, and a perspective view of a device that has undergone another conventional process for forming a pattern layer on a substrate. [Figure 5C] FIG. 5C shows a cross-sectional view, a plan view, and a perspective view of a device that has undergone another conventional process for forming a pattern layer on a substrate. [Figure 6A] FIG. 6A shows a cross-sectional view and a plan view of a device that has undergone a process for forming a pattern layer on a substrate according to an exemplary embodiment of the present disclosure. [Figure 6B]FIG. 6B shows a cross-sectional view and a plan view of a device that has undergone a process for forming a pattern layer on a substrate, according to an exemplary embodiment of the present disclosure. [Figure 6C] FIG. 6C shows a cross-sectional view and a plan view of a device that has undergone a process for forming a pattern layer on a substrate, according to an exemplary embodiment of the present disclosure. [Figure 6D] FIG. 6D shows a cross-sectional view and a plan view of a device that has undergone a process for forming a pattern layer on a substrate, according to an exemplary embodiment of the present disclosure. [Figure 7A] FIG. 7A shows a cross-sectional view and a plan view of a device that has undergone a process for forming a pattern layer on a substrate, according to another exemplary embodiment of the present disclosure. [Figure 7B] FIG. 7B shows a cross-sectional view and a plan view of a device that has undergone a process for forming a pattern layer on a substrate, according to another exemplary embodiment of the present disclosure. [Figure 7C] FIG. 7C shows a cross-sectional view and a plan view of a device that has undergone a process for forming a pattern layer on a substrate, according to another exemplary embodiment of the present disclosure. [Figure 8A] FIG. 8A shows a cross-sectional view of a device that has undergone a process for forming a pattern layer on a substrate, according to another exemplary embodiment of the present disclosure. [Figure 8B] FIG. 8B shows a cross-sectional view of a device that has undergone a process for forming a pattern layer on a substrate, according to another exemplary embodiment of the present disclosure. [Figure 8C] FIG. 8C shows a cross-sectional view of a device that has undergone a process for forming a pattern layer on a substrate, according to another exemplary embodiment of the present disclosure. [Figure 8D] FIG. 8D shows a cross-sectional view of a device that has undergone a process for forming a pattern layer on a substrate, according to another exemplary embodiment of the present disclosure. [Figure 9A] FIG. 9A shows a cross-sectional view of a device that has undergone a process for forming a pattern layer on a substrate, according to another exemplary embodiment of the present disclosure. [Figure 9B]Figure 9B shows a cross-sectional view of a device that has undergone a process for forming a patterned layer on a substrate, according to another exemplary embodiment of the present disclosure. [Figure 9C] Figure 9C shows a cross-sectional view of a device that has undergone a process for forming a patterned layer on a substrate, according to another exemplary embodiment of the present disclosure. [Figure 10] Figure 10 shows a cross-sectional view of a device being processed to form a pattern layer on a substrate using a conventional process. [Figure 11] Figure 11 shows a cross-sectional view of a device being processed to form a pattern layer on a substrate, according to an exemplary embodiment of the present disclosure. [Figure 12A] Figure 12A is a cross-sectional view of a device being processed to form a pattern layer on a substrate, according to an exemplary embodiment of the present disclosure. [Figure 12B] Figure 12B is an enlarged view of the area inside circle 12B in Figure 12A. [Figure 13A] Figure 13A is a cross-sectional view of a device being processed to form a pattern layer on a substrate, according to another exemplary embodiment of the present disclosure. [Figure 13B] Figures 13B and 13C are enlarged views of the portions within circles 13B and 13C in Figure 13A, illustrating the characterization of the different states in B and C. [Figure 13C] Figures 13B and 13C are enlarged views of the portions within circles 13B and 13C in Figure 13A, illustrating the characterization of the different states in B and C. [Figure 14] Figure 14 is a flowchart showing a workflow for forming a patterned layer on a substrate according to an exemplary embodiment of the present disclosure. [Figure 15] Figure 15 is a flowchart showing a workflow for forming a patterned layer on a substrate according to another exemplary embodiment of the present disclosure. [Figure 16] Figure 16 is a flowchart showing a workflow for forming a patterned layer on a substrate according to another exemplary embodiment of the present disclosure. [Figure 17]Figure 17 is a flowchart illustrating a workflow for forming a patterned copper layer on a substrate, for example, in the manufacture of a PCB, according to another exemplary embodiment of the present disclosure. [Figure 18] Figure 18 is a block diagram of the components of a system for forming a device according to various exemplary embodiments of the present disclosure. [Figure 19] Figure 19 is a flowchart showing a workflow for forming a patterned layer on a substrate according to another exemplary embodiment of the present disclosure. [Figure 20] Figure 20 is a micrograph of conductive features formed by a conventional process. [Figure 21] Figure 21 is a micrograph of a conductive feature formed by an exemplary embodiment of the present disclosure. [Modes for carrying out the invention]

[0015] Detailed explanation For the sake of simplification and clarity of the illustrations, the elements shown in the figures are not necessarily drawn to scale. For example, some dimensions of elements may be exaggerated relative to others for clarity. Furthermore, where appropriate, reference numerals may be repeated between figures to indicate corresponding or similar elements.

[0016] The following detailed description includes numerous specific details to provide a complete understanding of the disclosure. However, it will be understood by those skilled in the art that the disclosure can be implemented without these specific details. Where otherwise, well-known methods, procedures, and components are not described in detail so as not to obscure the disclosure.

[0017] Microchips, printed circuit boards, solar cells, electronic displays (including, but not limited to, liquid crystal displays, organic light-emitting diode displays, and quantum dot electroluminescent displays), and various other electrical or optical devices and components may consist of a number of overlapping layers, including patterned layers of different materials supported by a substrate. Various exemplary embodiments of this disclosure envision methods and devices for forming patterned layers on a substrate for adhesion in the fabrication of electrical and / or optical devices and / or components. As herein, “device layer” refers to a layer of material including a layer of a completed optical and / or electronic device and / or component in its final form, which may optionally be patterned; “patterned device layer” refers to such a layer after it has been patterned; and “unpatterned device layer” refers to such a layer before it has been patterned. For example, various exemplary embodiments envision a patterned device layer of conductive material including a set of conductive lines, which may be fabricated on a substrate as part of the manufacture of, for example, a printed circuit board (PCB) or other electronic component. According to embodiments of the present disclosure, an unpatterned device layer on a substrate, for example, a conductive layer of copper or other conductive material overlapping the electrically insulating surface of the substrate, may be coated with a “primer” layer containing an “undercut reducing” material that exhibits an effect of reducing undercuts during a wet etching process used to remove the device layer material exposed through an etching mask. For example, the undercut reducing material may be an anticorrosion material that includes a material that exhibits anticorrosion properties against the device layer material. Such anticorrosion materials may include polymers, organic materials, inorganic materials, Schiff bases, or other materials, for example, those disclosed in International Patent Application Publication Nos. WO2016 / 193978 A2 and WO2016 / 025949 A1, the entire contents of which are incorporated herein by reference. The anticorrosion material may be blanket-formed or deposited on the unpatterned device layer, or patterned or deposited.In various exemplary embodiments, the terms corrosion-preventive material and undercut-reducing material may be used synonymously.

[0018] Various exemplary embodiments of the present disclosure intend to form an etching mask on a substrate by forming a primer layer containing an undercut reduction material on an unpatterned device layer on the substrate, and then forming a patterned layer of etching resist material on the primer layer. Other exemplary embodiments of the present disclosure intend to form an etching mask on an unpatterned device layer on a substrate by forming a patterned layer of a mixture of the undercut reduction material and the etching resist material on the substrate, without the need to form a separation layer containing the undercut reduction material, such as a primer layer. In exemplary embodiments, a primer layer containing the undercut reduction material is formed on an unpatterned device layer on the substrate, and then an etching mask is formed on the primer layer, which is formed by patterning or depositing a liquid etching resist ink onto the primer layer, and then converting the liquid ink into an etching mask through subsequent processing, for example, by drying or baking the ink so that a solid patterned layer of etching resist material is formed, the liquid etching resist ink may contain a material that interacts with the primer layer. For example, a liquid etching resist ink undergoes a chemical reaction upon contact with a primer layer, thereby inhibiting the translation or spreading of the ink on the primer surface, for example, through a chemical reaction. In other embodiments, the liquid etching resist ink may be applied to a surface in the form of droplets delivered by an inkjet nozzle, and upon contact with the primer surface, such droplets may soon be effectively fixed or “frozen” in place so as to significantly reduce or completely stop any further translation or spreading of the ink droplets on the primer surface, as described in International Publication Nos. WO2016 / 193978 A2 and WO2016 / 025949 A1, the entire contents of which are incorporated herein by reference.In exemplary embodiments, suppression of the spreading of etching resist ink on the primer surface, for example, through a chemical reaction resulting from the interaction between the etching resist ink and the primer layer, can contribute to the precise deposition of the mask pattern on the patterned layer.

[0019] In exemplary embodiments, the primer layer is formed on an unpatterned device layer on a substrate, and the etching mask is formed on the primer layer by dispensing liquid etching resist ink in a pattern onto the primer layer and then converting the liquid ink into an etching mask through subsequent processing, for example, by drying or baking the ink so that a solid pattern layer resistant to subsequent etching is formed. In exemplary embodiments, the primer layer contains a first reactive component, and the liquid etching resist ink contains a second reactive component, and when the etching resist ink comes into contact with the primer layer, the first and second reactive components react to effectively fix or "solidify" the ink in place, thereby significantly reducing or completely stopping further translation or spreading of the ink on the primer surface. In exemplary embodiments, the primer layer comprises a third reactive component, and the liquid etching resist ink comprises a fourth reactive component. The reaction of the third and fourth reactive components produces an etching mask material that is relatively insoluble in the etching resist ink and relatively insoluble in the etching solution used to subsequently etch the non-patterned device layer (relatively insoluble, as defined herein with respect to the fourth reactive component). The etching mask material thus formed is referred herein to as a two-component material or two-component reaction product. In various embodiments, the reactive component that provides the majority of the mass to form the two-component material constituting the etching mask is called the etching resist component or the same thing, but the etching-resistant component, while the other reactive components are called the fixing component or the same thing, but the fixing-reactive component or fixing composition. In exemplary embodiments, the etching resist component comprises a number of materials. In exemplary embodiments, the fixing component comprises a number of materials. In exemplary embodiments, the etching resist ink is an aqueous ink, and the two-component material is relatively insoluble in water. In exemplary embodiments, the etching solution is an acidic etching solution, such as a mixture of copper chloride and hydrogen peroxide, for example, but not limited to these. In exemplary embodiments, one or more of the first, second, third, or fourth components include a number of materials.In exemplary embodiments, the first and third components are the same. In exemplary embodiments, the second and fourth components are the same. In exemplary embodiments, the reaction to produce the two-component material is the same as the reaction to immobilize droplets of etching resist ink onto the primer layer. In exemplary embodiments, the primer layer includes an undercut prevention material. In exemplary embodiments, the reactive component of the primer (e.g., the first or third reactive component described above) includes an undercut prevention material. In exemplary embodiments, the reactive component of the etching resist ink (e.g., the second or fourth reactive component described above) includes an undercut prevention material. In exemplary embodiments, the etching resist ink includes an undercut prevention material.

[0020] In exemplary embodiments, at least one of the primer or etching resist ink may contain polyvalent and / or polycationic groups and / or polyvalent inorganic cations. In exemplary embodiments, at least one of the primer or etching resist ink may contain polyanionic groups. In exemplary embodiments, at least one of the primer or etching resist ink may contain a reactive anionic component, which may be water-soluble. In exemplary embodiments, such a reactive anionic component may contain at least one anionic polymer (in base form) at a pH higher than 7.0. In exemplary embodiments, such anionic polymers may be selected from acrylic resins and styrene-acrylic resins, which are in soluble salt form (for example, but not limited to sodium salt form), and sulfone resins, which are in soluble salt form (for example, but not limited to sodium salt form). In exemplary embodiments, such anionic polymers may be in ammonium form or amine-neutralized form. In exemplary embodiments, such anionic polymers may take the form of a polymer emulsion or dispersion. In various embodiments, the reaction that produces the two-component material causes a significant increase in the viscosity of the etching resist ink on the primer layer, and the immobilization phenomenon is substantially derived from this increase in viscosity. In various embodiments, the etching resist ink provides the majority of the material mass that forms the two-component material. In various embodiments, the primer provides the majority of the material mass that forms the two-component material, in which case the primer layer may contain the etching resist component and the etching resist ink may contain the fixing component. In various embodiments, the primer layer is formed by providing a coating of liquid primer ink on the unpatterned device layer, and then processing the layer to form the primer layer by, for example, drying or baking the layer. In various embodiments, such primer ink is aqueous. In various embodiments, the primer layer adheres well to the unpatterned device layer.In various embodiments, the primer layer is applied to the unpatterned device layer by inkjet printing, spray coating, metered rod coating, roll coating, dipping coating, or any other suitable printing or coating method. In various embodiments, the primer layer may be a uniform (e.g., blanket) coating or a patterned coating.

[0021] In an exemplary embodiment, the primer layer is formed by depositing a surface-activated solution onto the non-patterned device layer, at least partially. The surface activating solution comprises one or more of the following: copper salt, ferric salt, chromium sulfuric acid, persulfate, sodium chlorite, and hydrogen peroxide. In exemplary embodiments, the unpatterned device layer is a metal layer, and the surface activating solution is applied to the surface of the metal layer. In exemplary embodiments, the surface activating solution may be applied for a predetermined period of time and then washed off for, for example, 10 seconds, 20 seconds, 30 seconds, 60 seconds, or longer. In exemplary embodiments, the surface activating solution may be applied by immersing the surface in a bath containing the surface activating solution. In exemplary embodiments, the surface activating solution may be applied by spraying the surface activating solution onto the surface or by any other suitable method. In exemplary embodiments, the surface activating solution is washed off the surface using a cleaning fluid, for example, an alcohol solution, ethanol, propyl alcohol, isopropyl alcohol, and acetone, but not limited to these. In exemplary embodiments where the surface is a copper layer, such as the surface of a PCB, a surface-activated aqueous solution of CuCl2 (or any divalent copper salt) is used at a concentration of 0.5 to 1.0 weight percent, and the primer layer is formed by immersing the copper surface in a bath containing the surface-activated solution for 30 seconds, at least in part. In exemplary embodiments where the surface is a copper layer, such as the surface of a PCB, a surface-activated aqueous solution of Na2S2O8 (or any persulfate) is used at a concentration of 0.5 to 1.0 weight percent, and the primer layer is formed by immersing the copper surface in a bath containing the surface-activated solution for 30 seconds, at least in part. In exemplary embodiments where the surface is a copper layer, such as the surface of a PCB, a surface-activated aqueous solution of H2O2 is used at a concentration of 10 weight percent, and the primer layer is formed by immersing the copper surface in a bath containing the surface-activated solution for 30 seconds, at least in part. In an exemplary embodiment, where the surface is a copper layer, such as the surface of a PCB, a surface-activated aqueous solution of FeCl3 is used at a concentration of 20 wt percent, and the primer layer is formed by immersing the copper surface in a bath containing the surface-activated solution for 10 seconds, at least partially.In exemplary embodiments where the surface is a copper layer, such as the surface of a PCB, a surface-activated aqueous solution of HCrO4 / H2SO4 is used at a concentration of 5 wt percent, and the primer layer is formed by immersing the copper surface in a bath containing the surface-activated solution for 30 seconds, at least in part. In exemplary embodiments where the surface is a copper layer, such as the surface of a PCB, a surface-activated aqueous solution of NaClO2 is used at a concentration of 5 wt percent, and the primer layer is formed by immersing the copper surface in a bath containing the surface-activated solution for 60 seconds, at least in part.

[0022] In exemplary embodiments where an etching resist ink is printed onto a primer layer using an inkjet printer, the substrate may be at approximately "room" temperature, for example, in the range of 20°C to 30°C, or at a high temperature, for example, around 100°C. In exemplary embodiments, the two-component etching mask may have a thickness of at least 0.01 μm. In exemplary embodiments, the two-component etching mask may have a thickness of less than 12 μm.

[0023] In exemplary embodiments of the present disclosure, a primer layer is deposited on a substrate, and etching mask ink is subsequently deposited on the primer layer using inkjet printing and then baked to form an etching mask layer. Shortly after contact with the primer layer, droplets of etching mask ink interact with the primer layer, and as a result of a chemical reaction between a first reactive component in the primer layer and a second reactive component in the etching mask ink, the ink droplets are effectively immobilized or “solidified” such that further spreading and / or translation is significantly reduced or eliminated. Furthermore, one or more components of the etching mask ink react with one or more components of the primer layer to form a two-component etching mask material that is relatively insoluble in the etching mask ink and relatively insoluble in the etching solution in which the etching mask will be used together (relatively insoluble is defined herein as an etching mask ink that reacts to form a two-component etching mask material). For example, the etching mask ink may be aqueous, and the etching mask material obtained from such a reaction will be insoluble in water, and the etching solution may be an acidic etching solution, and the etching mask material obtained from such a reaction will be insoluble in the acidic etching solution.

[0024] In exemplary embodiments, coating an unpatterned device layer, such as a copper layer, with an undercut-reducing material, such as a corrosion-resistant material, is applicable to any process that uses an etching mask to prevent the device layer material from being wet-etched. Other metal layers besides copper may be used in exemplary embodiments, but are not limited to, aluminum, stainless steel, gold, and metal alloys. Exemplary embodiments of the present disclosure involve introducing an undercut-reducing material in the form of a primer layer before depositing a photoresist layer onto an unpatterned device layer, for example via lamination, slot die coating, or spin coating, which is then patterned via exposure to light of a selected wavelength, such as UV light, through a photomask, or via direct laser imaging.

[0025] The behavior of undercut-reducing materials during a chemical etching process can mitigate (e.g., reduce and eliminate) the appearance of undercuts in device layer features obtained from a patterning process. Thus, after a chemical etching process, device layer features with more vertical and less sloped sidewalls may be formed compared to device layers formed without undercut-reducing materials, due to the reduction or elimination of undercuts. When applied to a patterned device layer containing a conductive material capable of transmitting current or electrical signals, various embodiments of the present disclosure can enhance the overall performance of the thus formed electrical circuit, improve the overall conductivity of individual conductive features, enhance the frequency response, and enable the production of patterns with both higher density and thinner features and narrower spaces between features. Similar benefits can also be induced in components by using patterned device layers of non-metallic materials, such as optical or insulating patterned features.

[0026] In conventional wet etching processes, as the liquid etchant progresses downwards through the thickness of the device layer material being etched in areas not covered by the etching mask (e.g., towards the substrate), it is thought that the liquid etchant also progresses laterally toward the lateral surfaces (sidewalls) of such portions of the device layer material covered by the etching mask. As the etching depth increases, more of the sidewalls are exposed to lateral etching, and therefore the portion of the sidewall closest to the etching mask is exposed to the liquid etchant for a longer period than the portion of the sidewall closest to the substrate, and is subjected to correspondingly increased lateral etching, thus giving the sidewalls of the resulting patterned device layer features an undercut shape. In other words, the time for the etchant to react with the device layer material to remove portions of the device layer material increases with distance from the substrate. While not adhering to any particular theory, in conventional wet etching processes, despite the intention of the etching mask to prevent the removal of device layer material in those areas, whether carried out by immersion or by spraying or atomizing the etchant, the additional reaction time between the etchant and the portion of device layer material further obtained from the substrate is thought to result in lateral inward erosion (removal) of the device layer material in the region of the device layer material directly beneath and adjacent to the etching mask features. A further explanation and illustration of this phenomenon is presented below in relation to Figures 4B-5C.

[0027] As discussed in various exemplary embodiments of this disclosure, the reaction between the etchant and the portion of the device layer material corresponding to the lateral surface of the patterned device layer features, or the same as the sidewall, is mitigated (e.g., reduced, prevented, inhibited) during the wet etching process, thereby mitigating the formation of undercut shapes on the lateral surface.

[0028] Figures 1A–5C all illustrate various stages of device fabrication for forming a patterned device layer on a substrate, or the same as forming patterned device layer features on a substrate, using various conventional processes. In exemplary embodiments, the device is a PCB in the process of being manufactured, and the device layer material is an electrically conductive material. However, those skilled in the art will understand that the reference to PCB is non-limiting and merely illustrative, and that various applications, such as the various electronic and optical components mentioned above, are encompassed within the scope of this disclosure. Referring now to Figures 1A–1D, various diagrams of device 100 fabricated to form patterned device layer features using one conventional process. Figure 1A is a plan view and a side view of device 100, which includes a substrate 102 and on which an unpatterned device layer 104 is disposed.

[0029] The substrate 102 itself comprises a number of layers, including, for example, one or more unpatterned or patterned device layers. For example, although the unpatterned device layer 104 is shown on one side of the substrate 102 (e.g., the “top” in the orientation shown in the figure), the disclosure also intends to process “both sides” of the device 100, and for example, the substrate 102 includes a second unpatterned device layer positioned to include the opposite side of the substrate 102 (e.g., the “bottom”). In exemplary embodiments, such an “bottom” side unpatterned device layer is subjected to a patterning process similar to that of the “top” side unpatterned device layer 104, and such “bottom” side patterning is performed, in whole or in part, before, after, or between the “top” side patterning of the unpatterned device layer 104. In exemplary embodiments, the substrate 102 may include one or more patterned device layers processed by one or more exemplary embodiments, using a method similar to that used to process, for example, the unpatterned device layer 104.

[0030] In one exemplary embodiment, device 100 is a PCB in the manufacturing process, and an unpatterned device layer 104 comprises an electrically conductive material, thereby making the layer an unpatterned electrically conductive device layer, and the substrate 102 comprises a layer of one or more electrically insulating materials configured to provide an “upper” electrically insulating surface and a “bottom” electrically insulating surface, with the unpatterned electrically conductive device layer 104 positioned adjacent to the “upper” electrically insulating surface. A second unpatterned electrically conductive device layer is incorporated into the substrate 102 and positioned adjacent to the “bottom” electrically insulating surface (such a “bottom” electrically insulating surface is located within the substrate 102 and is not shown in Figure 1), and the “bottom” surface of the substrate 102, i.e., the surface opposite to the surface adjacent to the unpatterned device layer 104, is the surface of the second unpatterned electrically conductive device layer.

[0031] In one exemplary embodiment, device 100 is a PCB in the manufacturing process, and substrate 102 has an electrically insulating surface over a region including at least a portion of the interface between substrate 102 and the unpatterned device layer 104. In one exemplary embodiment, substrate 102 may include a layer of electrically insulating material, such as a composite material containing glass fibers bonded together with epoxy resin or other material, for example, but not limited to such composite materials. Such an electrically insulating material may have a thickness ranging from, for example, about 0.001 inches to about 0.05 inches. In one exemplary embodiment, the substrate 102 may include a number of layers in which electrically insulating and electrically conductive materials are arranged alternately, and may further include at least two electrically insulating layers, each containing glass fibers bonded with epoxy resin or other material, having a thickness of 0.001 inches to 0.05 inches, and including, for example, one “core” layer and one layer containing a pre-bonded sheet (which may be called a “prepreg”), at least one patterned electrically conductive layer placed between the electrically insulating layers, and the “top” surface of the substrate 102 that aligns with the unpatterned device layer 104 is one surface of the at least two electrically insulating layers. In an exemplary embodiment, the prepreg includes an FR4 grade epoxy laminated sheet. In an exemplary embodiment, the core layer includes an FR4 grade epoxy laminated sheet.

[0032] The unpatterned device layer 104 may include a layer of conductive material, such as a metal or metal alloy, including, but not limited to, copper, aluminum, silver, gold, or other conductive materials familiar to those skilled in the art. In exemplary embodiments, the unpatterned device layer 104 is a copper foil laminated on the substrate 102, and the interface between the substrate 102 and the unpatterned device layer 104 is electrically insulated; however, other conductive materials are considered to be within the scope of this disclosure.

[0033] Referring next to Figure 1B, in the next step of processing, an etching mask 106 is formed on the exposed surface 110 of the unpatterned device layer 104. The etching mask 106 may be formed in a desired pattern 108, such as lines corresponding to lines of the patterned device layer that are desired on the device 100 after processing, as shown in Figure 1B. In other words, the etching mask 106 may include an etching resist material deposited on the unpatterned device layer 104 at locations corresponding to where the patterned device layer features are desired on the device 100. The etching mask 106 may include a material such as a polymer, oxide, nitride, or other material. In one exemplary embodiment, the etching mask material is a polymer formed using a negative-type photoresist material, for example, one of the SU-8 series photoresists supplied by MicroChem Corp., 200 Flanders Road, Westborough, MA 01581 USA. In one exemplary embodiment, the etching mask material is a polymer formed using a positive-type photoresist material, for example, one of the ma-P 1200 series photoresists supplied by micro resist technology GmbH, Kopenicker Str. 325, 12555 Berlin, DE. The etching mask 106 can be patterned on the surface of the unpatterned device layer 104 by methods such as silkscreen printing, inkjet printing, photolithography, gravure printing, stamping, photorelief printing, or other methods. After the etching mask 106 is attached to the surface 110 of the unpatterned device layer 104, the device 100 is exposed to an etchant, such as a chemical etchant, to remove the material of the unpatterned device layer 104 from areas not protected by the etching mask 106, resulting in the formation of a patterned device layer 114 as shown in Figure 1C. Such a chemical etchant may contain a compound that exhibits a corrosive effect on the material of the unpatterned device layer 104.In exemplary embodiments, the unpatterned device layer 104 is an electrically conductive layer, and such a chemical etchant may include, but is not limited to, ammonium persulfate, ferric chloride, or other compounds that exhibit a corrosive effect on the material of the unpatterned device layer 104. In one embodiment, the unpatterned electrically conductive device layer 104 contains copper, and the etchant used is copper chloride (CuCl2). Those skilled in the art will be familiar with a variety of chemical etchants suitable for removing the material of the unpatterned device layer 104.

[0034] Continuing to refer to Figure 1C, when the unpatterned device layer 104 is exposed to the etchant, the etchant dissolves (e.g., corrodes) the material of the unpatterned device layer 104, starting from the exposed upper surface 110. As the material of the unpatterned device layer 104 is removed, the etchant may also remove portions of the material of the unpatterned device layer 104 below the etching mask 106, resulting in non-vertical sidewalls 112 that are not straight. For example, in the device 100 produced by the process shown in Figures 1A-1D, as shown in Figure 1C, the sidewalls 112 of the features of the patterned device layer 114 produced by the pattern 108 of the etching mask 106 may exhibit a tapered shape, for example, from a first feature with a width W1 at the interface between the patterned device layer 114 and the etching mask 106 to a second feature with a width W2 that is wider than the width W1 of the first feature at the interface between the substrate 102 and the patterned device layer 114. Figure 1D shows the device 100 after the etching mask 106 has been removed, exposing the patterned device layer 114. The tapered shape shown in Figure 1D by the feature sidewalls 112 of the patterned device layer 114 is one example of an "undercut" sidewall, which will be discussed in more detail below in relation to Figures 4A-4C. Other shapes and arrangements of undercut sidewalls may occur, including sidewalls that are not substantially straight and do not extend substantially perpendicular to the surface of the substrate on which they are formed.

[0035] Referring next to Figures 2A-2C, a method for forming an etching mask 206 having a conductive line pattern 208 is shown. The device 200 having a substrate 202 and an unpatterned device layer 204 is such that the entire area of ​​the unpatterned device layer 204 is covered (i.e., blanket coated) with an unpatterned etching resist layer 216. The unpatterned etching resist layer 216 is then exposed to light (e.g., UV light) in a certain pattern so that the exposed area is relatively resistant to removal in the subsequent development process (so-called negative processing), or so-called positive processing so that the exposed area is relatively more resistant to removal in the subsequent development process. Exposure used in such a pattern can be achieved in a so-called direct drawing process in a certain pattern as a function of time, for example, by shining light through a photomask as in so-called photolithography, or by sending a series of pulses or scans of focused light, for example in the form of a laser beam, onto the etching resist layer 216. The development process removes the material of the unpatterned etching resist layer 216 in accordance with the pattern exposure, resulting in a patterned etching mask 206 having a pattern 208 as shown in Figure 2C. The development process may also include immersing the device 200 in a liquid developer that dissolves or corrodes the material of the unpatterned etching mask layer 216. For example, but not limited to, a negative process makes removal relatively easier, and the developer liquid may dissolve the material of the unpatterned etching resist layer 216 that has not been exposed to UV light, while a positive process may dissolve the material of the unpatterned etching resist layer that has been exposed to UV light. The removal of the portion of the unpatterned device layer 204 not protected by the etching mask 206 then proceeds as discussed above in relation to Figure 1D, resulting in a device 200 having a patterned device layer that has the characteristics of pattern 208 and exhibits undercuts.

[0036] Alternatively, the etching mask may be deposited directly onto the unpatterned device layer in a desired pattern, without the intermediate step of patterning the unpatterned etching resist layer, as in the embodiments of Figures 2A-2C. For example, referring to Figures 3A and 3B, the etching mask 306 may be formed directly onto the unpatterned device layer 304 of the device 300 as a desired pattern 308 of lines corresponding to the desired locations of the patterned device layer features on the resulting device. The etching mask 306 may be deposited on the unpatterned device layer 304 in the desired pattern 308 by, for example, inkjet printing, lamination, screen printing, gravure printing, stamping, or other methods. In one exemplary embodiment, the etching mask 306 is formed on the unpatterned device layer 304 using inkjet printing, where an inkjet printhead having multiple nozzles ejects droplets of liquid etching resist ink onto the device 300 to form a coating of liquid etching resist ink corresponding to the pattern 308, and such a coating of liquid etching resist ink is subsequently processed so that the liquid coating is converted into an etching mask 306. In one exemplary further embodiment, processing of the liquid etching resist ink includes drying and / or baking the device so that a solid etching mask 306 is formed from the liquid coating. In one exemplary embodiment, the etching mask 306 is formed on an unpatterned device layer 304 using an inkjet printer which includes one or more print heads including a plurality of nozzles, a substrate support for holding the substrate, a stage for moving the plurality of nozzles and the substrate relative to each other, a motion control system for controlling the relative position of the substrate and the nozzles, and a nozzle control system for controlling the initiation of the nozzles, configured to deliver droplets onto the substrate in a desired pattern. In any embodiment in which inkjet printing is utilized to deposit the liquid coating, it is intended that an inkjet printing system as described herein may be used.

[0037] Figures 4A–4C illustrate a conventional process for removing material from the unpatterned device layer 404 of device 400, which is thought to occur during a wet etching process that causes undercuts. In Figure 4A, the unpatterned device layer 404 is covered by an etching mask 406 corresponding to a pattern 408. Device 400 is then exposed to a chemical etchant 418. In an exemplary embodiment of Figure 4B, the exposure is performed by immersion in the etchant 418. The etchant 418 removes material from the unpatterned device layer 404 (from Figure 4A) so that a partially patterned device layer 405 is created. For example, in the embodiment of Figure 4B, the etchant 418 contains a liquid, for example, a solution, contained in a tank 420, and device 400 with the etching mask 406 (Figure 4B) is immersed in the etchant 418 as shown in Figure 4B. As the exposed portion of the upper surface 410 (Figure 4A) of the unpatterned conductive layer 404 is etched away and the sidewall 412 begins to form, the sidewall 412 is exposed to the etchant 418, which removes material from the sidewall 412, resulting in the tapered undercut shape characteristic of the patterned device layer 414 shown in Figure 4C. In other words, the etchant 418, which can act uniformly in all directions, invades the material including the device layer laterally under the etching mask 406 as soon as the upper surface 410 of the unpatterned device layer 404 is etched away (whether the device layer is in its unpatterned state, i.e., 404, partially patterned state, i.e., 405, or patterned state, i.e., 414). The amount of material of the device layer removed by the etchant 418 may depend on the length of time the material of the device layer is exposed to the etchant 418. Therefore, as the etchant 418 progresses through the thickness of the partially patterned device layer 405 (i.e., perpendicular to the plane of the substrate 402), the portion of the sidewall 412 closer to the etching mask 406 is exposed to the etchant 418 for a longer period than the portion of the sidewall 412 closer to the substrate 402, thereby imparting the tapered (i.e., undercut) shape of the sidewall 412 as shown in Figure 4C.In other words, the time it takes for the etchant to react with the material in the device layer and remove such material from the device layer increases with distance from the substrate. Therefore, although we are not bound by any particular theory, the additional reaction time between the etchant and the material in parts of the device layer that are far from the substrate is thought to lead to erosion (removal) of the material from the device layer in a lateral inward direction in the region of the device layer, directly beneath and in close proximity to the etching mask, even though the intention of the etching mask is to prevent the removal of material from the device layer in those areas.

[0038] Next, referring to Figures 5A-5C, another embodiment of a conventional process is shown. The process in Figures 5A-5C is similar to that described in relation to Figures 4A-4C and includes forming an etching mask 506 on the unpatterned device layer 504 of the device 500, as shown in Figure 5A. Rather than immersing the device 500 in the etchant 518 as shown above in relation to Figure 4B, the etchant 518 is introduced as a jet 522 that impacts the device 500, which may be in a tank 520, as shown in Figure 5B. Excess etchant 518 can flow into a drain 524 of the tank 520 or be collected by other means for recirculation or other processing. Since the etchant 518 acts in all directions, tapers or undercuts are formed on the sidewalls 512 of the features of the resulting patterned device layer 514, as shown in Figure 5C.

[0039] As discussed above, the formation of undercut sidewalls on the feature of the patterned device layer on the device introduces various constraints on the size and shape of the features that can be formed. For example, as discussed above, the tendency for undercuts to form may impose constraints on the minimum feature width or minimum spacing between features that can be generated, thereby limiting the feature density on the device. In various applications, performance is improved by maximizing the feature density on the device. In various embodiments, the device layer includes an electrically conductive material, the device is a PCB, and the tendency for undercuts may limit the minimum feature width, minimum spacing between features, and maximum feature density.

[0040] Figures 6A-617 illustrate various embodiments of processes for reducing (e.g., reducing or eliminating) undercuts that occur during conventional processing. For example, referring to Figure 6A, the device 600 has an unpatterned device layer 604 on a substrate 602. The unpatterned device layer 604 may be attached to the substrate by chemical vapor deposition, physical vapor deposition, lamination, slot die coating, spin coating, inkjet printing, screen printing, nozzle printing, gravure printing, rod coating, or any other suitable method, as is familiar to those skilled in the art. The unpatterned device layer 604 is coated with an anticorrosion layer 629, and then an etching mask 628 is formed on the anticorrosion layer 629. The anticorrosion layer 629 may be attached to the substrate by chemical vapor deposition, physical vapor deposition, lamination, slot die coating, spin coating, inkjet printing, screen printing, nozzle printing, gravure printing, rod coating, or any other suitable method, as is familiar to those skilled in the art. In some embodiments, the corrosion protection layer 629 includes a “primer” layer, and the etching mask 628 is formed by depositing a liquid etching resist ink on the primer layer, which is converted into the etching mask 628 through subsequent processing, e.g., drying or baking, but not limited to these processes. In various embodiments, as described above, such liquid etching resist ink may be delivered to the device 600 in the form of droplets via inkjet printing, and such droplets can interact with the corrosion protection layer 629 (which in such cases functions as the primer layer) in such a manner that they are rapidly (e.g., on the order of microseconds) effectively fixed or “solidified” in place upon contact with the primer surface, and thus further translation or spreading of the ink droplets on the primer surface is greatly reduced or completely stopped, as further discussed in International Publication Nos. WO2016 / 193978 A2 and WO2016 / 025949 A1 incorporated by reference above. Such liquid etching resist ink may further generate a two-component material that forms at least partially the etching resist mask through interaction with such primer layer.

[0041] In various embodiments, referring to Figure 6A, the device 600 is a PCB, the unpatterned device layer 604 comprises an electrically conductive material such as copper, aluminum, gold, and / or other metals, and the surface of the substrate 602 adjacent to the unpatterned electrically conductive device layer 604 is electrically insulating.

[0042] In exemplary embodiments, the corrosion protection layer 629 may include materials selected based on their ability to prevent the corrosive action of chemical etchants used to remove material from the unpatterned device layer 604 of device 600. In non-limiting examples, the corrosion protection layer 629 may include, but is not limited to, polymers, organic compounds, such as organic compounds containing one or more -imine groups, one or more -amine groups, one or more -azole groups, one or more -hydrazine groups, one or more amino acids, Schiff bases, or other materials. In other exemplary embodiments, the corrosion protection layer 629 may include inorganic materials such as chromate, molybdate, tetraborate, or another inorganic compound. In some exemplary embodiments, the corrosion protection layer 629 may include reactive compounds such as one or more reactive cationic groups containing polycations and / or polyvalent cations. The cationic reactive component may be able to adhere to a metallic surface, such as a copper surface.

[0043] In some embodiments, the corrosion protection layer 629 may be formed by depositing a liquid corrosion protection ink onto an unpatterned device layer using any known deposition method, such as, but not limited to, spraying, spin coating, nozzle printing, rod coating, screen printing, coating, inkjet printing, or similar, and then processing the device 600 so that the liquid coating is converted into the corrosion protection layer 629. In some embodiments, the corrosion protection layer 629 may be referred to as the primer layer, and the liquid corrosion protection ink may be referred to as the primer ink. The liquid corrosion protection ink may contain a solution that may contain polyimines such as polyethyleneimines, such as linear polyethyleneimines or branched polyethyleneimines, having low or high molecular weights. In non-limiting examples, the molecular weight may range from about 800 to about 2,000,000.

[0044] In some embodiments, to enable the liquid anticorrosive ink to be ejected via an inkjet printhead, the liquid ink may be an aqueous solution containing additional active ingredients such as propylene glycol, n-propanol, and wetting additives (such as TEGO 500 supplied by Evonik Industries).

[0045] In some embodiments, the thickness of the anticorrosion material layer 629 may be in the range of about 0.03 μm to about 1.1 μm. In some embodiments, the method may include drying the adhered ink using any drying method that forms a solid coating. In some embodiments, the method may include baking the adhered ink using any drying method that forms a solid coating.

[0046] As a further non-limiting example, if present, the cationic reactive components of the anticorrosion material layer 629 may include polyamides, such as polyethyleneimine, polyquaternary amines, long-chain quaternary amines, and polytertiary amines at various pH levels, as well as polyvalent inorganic cations, such as magnesium cations, zinc cations, calcium cations, copper cations, ferric cations, and ferrous cations. Polymer components may be introduced into the formulation either as soluble components or in emulsion form.

[0047] The corrosion protection layer 629 may be attached to the unpatterned device layer 604 using any suitable printing or coating method, including but not limited to inkjet printing, spraying, metering rod coating, roll coating, dip coating, spin coating, screen printing, lamination, stamping, and others. The corrosion protection layer 629 may be uniformly attached to the unpatterned device layer 604, or it may be attached to a desired pattern, such as a pattern 608 (as shown in Figure 6) that defines a desired pattern on the patterned device layer 630.

[0048] In the exemplary embodiments shown in Figures 6A–6D, the corrosion protection layer 629 may include a “primer” layer, and the etching mask 628 may be formed by depositing a liquid etching resist ink onto the primer layer, which is converted into the etching mask 628 through subsequent processing, such as drying or baking, but not limited to. In various embodiments, such drying may include baking at a temperature of 70°C or higher, but not limited to. In various embodiments, as described above, such liquid etching resist ink may be delivered to the device 600 in the form of droplets via inkjet printing, and such droplets may interact with the primer layer in such a manner that they are rapidly fixed in place or “solidified” (e.g., in about microseconds) by contact with the primer surface, so that further translation or spreading of the ink droplets on the primer surface is greatly reduced or completely stopped, as further discussed in International Publication Nos. WO2016 / 193978 A2 and WO2016 / 025949 A1 incorporated by reference above. Such liquid etching resist inks may be further produced through the interaction of such a primer layer with a two-component material that forms at least partially an etching mask.

[0049] The etching mask 628, or the liquid etching resist ink used to prepare such an etching mask 628 (as in the various embodiments described above), may contain a water-soluble polymer component and may contain anionic groups. The anionic polymer may be selected from acrylic resins and styrene-acrylic resins in the form of their dissolved salts. The anionic polymer may be selected from sulfone resins in the form of their dissolved salts, e.g., sodium, ammonium-, or amine-neutralized forms. In embodiments utilizing the liquid etching resist ink, the liquid ink may contain additional active ingredients to improve the printing or other deposition quality of the material.

[0050] The etching mask 628, or the liquid etching resist ink used to prepare such an etching mask 628 (according to certain embodiments described above), may contain a reactive component which may be water-soluble, and may contain a reactive anionic group. A non-limiting example of an anionic reactive component may contain at least one anionic polymer (in basic form) at a pH higher than 7.0. The anionic polymer may be selected from acrylic resins and styrene-acrylic resins which are in their soluble salt form. The anionic polymer may be selected from sulfone resins which are in their soluble salt form which may be, for example, sodium salt form, ammonium or amine neutralized form, and polymer emulsion or dispersion form. The polymer component may be introduced into the formulation as either a soluble component or in emulsion form.

[0051] Referring to Figure 6B, the corrosion protection layer 629 and etching mask 628 can be printed directly onto the device 600. In one exemplary embodiment, the corrosion protection layer 629 can be formed by printing on an unpatterned device layer 604 with a desired pattern, such as pattern 608, to facilitate the fabrication of a correspondingly patterned device layer 630 (as shown in Figure 6). The corrosion protection layer 629 may be deposited to a thickness of about 100 nm or less, ranging from about 5 nm to about 100 nm, or about 1 μm or less. Other thicknesses of the corrosion protection material layer 629 are conceivable within the scope of this disclosure and may depend on the specific application. The etching mask 628 is then formed by printing on the corrosion protection material layer 629 with a desired pattern, such as pattern 608, to facilitate the fabrication of a correspondingly patterned device layer 630 (as shown in Figure 6). The etching mask 628 may be deposited to have a thickness ranging from approximately 1 μm to approximately 5 μm, or approximately 5 μm or less, or approximately 15 μm or less.

[0052] The device 600 is then introduced into an etchant such as the liquid chemical etchant 418 or 518 discussed in relation to Figures 4B and 5B. The presence of the anticorrosion material layer 629 may contribute to a reduction in the amount of undercut of the features of the patterned device layer 630, as shown in Figures 6C and 6D. For example, the features of the patterned device layer 630 may exhibit a first width W1 adjacent to the anticorrosion layer 629 and a second width W2 adjacent to the substrate 602. In some exemplary embodiments, the difference between widths W1 and W2 results in a feature of the patterned device layer 630 exhibiting tapered sidewalls 632 (i.e., the features of the patterned device layer 630 may exhibit some degree of undercut). The undercut exhibited by the features of the patterned device layer 630 may be less than the undercut exhibited by the features of the patterned device layers 114, 414 (Figures 1D and 4D) discussed above. The degree of undercut may be quantified using various measurements, as will be discussed in more detail below in relation to Figures 10 and 11.

[0053] In the exemplary embodiments shown in Figures 7A-7C, the protective layer 729 is a blanket deposited on the surface of an unpatterned device layer 704 deposited on a substrate 702. Such blanket coating may be carried out by methods such as chemical vapor deposition, physical vapor deposition, lamination, inkjet printing, spraying, metering rod coating, roll coating, dipping coating, spin coating, screen printing, nozzle printing, or other methods, but are not limited to these. The etching mask 728 may be formed on the protective layer 729 with a desired pattern, such as the pattern 708 discussed in relation to the various embodiments described above. The method proceeds similarly to the embodiments shown in Figures 6A-6C described above. For example, a device 700 with the protective layer 729 and etching mask 728 is exposed to an etchant such as etchant 418 or 518 discussed in relation to Figures 4B and 5B. As shown in Figure 7B, the device 700 is placed in a tank 720, and the etchant 718 is sprayed onto the surface of the device 700 where the etching mask 728 is placed. The etchant 718 removes the protective layer 729 from the surface of the unpatterned device layer 704, exposing the material of the unpatterned device layer 704 removed by the etchant 718 as shown in Figure 7B, and can form a patterned device layer 730 having sidewalls 732 that show a reduced degree of undercut compared to the sidewalls 112 associated with the patterned device layers 114, 414 produced by a conventional process. The partially patterned device layer 705 reflects an intermediate state of the device layer after the protective layer 729 has been removed from the area exposed through the etching mask and a portion of the material of the device layer itself has been etched away, and before the etching has progressed sufficiently to form the patterned device layer 730.

[0054] Referring next to Figures 8A-8D, a more detailed illustration of a part of the process in the embodiment shown in Figures 7A-7C is provided. In Figure 8A, a jet of etchant 822 (such as etchant 718 in Figure 7B) strikes the surface of the protective layer 829 and the etching mask 828, which are deposited on the unpatterned device layer 804 on the substrate 802. The protective layer 829 may preferentially adhere to the surface of the device layer material and may become at least partially soluble in the etchant 718, while the etching resist material 828 may be substantially insoluble in the etchant 718. The jet 822 of the etchant 718 may contain sufficient kinetic energy to remove the corrosion protection layer 829 from the unpatterned device layer 804 in the region exposed through the etching mask, as shown in Figure 8B, and the etchant 718 may then begin to remove the material of the unpatterned device layer 804 that is not covered by the etching resist material 828, forming a partially patterned device layer 805, as shown in Figure 8C. Figure 8D shows the device 800 after the partially patterned device layer 805 has been sufficiently etched to form a patterned device layer 830. As shown in Figure 8D, the patterned device layer 830 has sidewalls 832 that exhibit less undercut than the sidewalls produced by the conventional process described in relation to Figures 1A-5C. Although the patterned device layer 830 is shown with a slight undercut in Figure 8D, this disclosure intends for a patterned device layer (e.g., conductive) feature that is substantially free of undercuts (i.e., substantially straight and extending perpendicularly to the surface of the substrate 802).

[0055] Next, referring to Figures 9A-9C, another embodiment of the process for forming a patterned device layer 930 on device 900 is shown. An unpatterned device layer 904, placed on substrate 902, is masked with a corrosion protection layer 929 and an etching mask 928. Device 900 is introduced into a tank 920 with an etchant 918, so that in Figure 9B the device is immersed in the etchant 918. As shown in Figure 9C, the patterned device layer 930 obtained on device 900 has sidewalls 932 that exhibit less undercut than the undercut indicated by the conductive feature 114 (Figure 1D) associated with the conventional process.

[0056] Referring now to Figure 10, an enlarged view of the device 100 discussed in relation to the conventional methods of Figures 1A-5C is shown. In Figure 10, the features of the patterned device layer 114 show tapered sidewalls extending between the interface between the etching mask 106 and the patterned device layer 114 and the interface between the patterned device layer 114 and the substrate 102. The patterned device layer features 114 show a first width W1 at the interface between the patterned device layer 114 and the etching mask 106, and a second width W2 at the interface between the patterned device layer 114 and the electrically insulating substrate 102. Figure 10 is drawn for illustrative purposes and various types of profiles may occur, but generally the patterned device layer 114 has a wider width at the interface with the substrate than at the interface with the etching resist material. Note that the etching mask 106 has a width W3 intended by this disclosure which is greater than, less than, or equal to the width W2.

[0057] Next, referring to Figure 11, an enlarged view of device 1100 similar to devices 600, 700, 800, or 900 shown in Figures 6A-9C is provided. In this exemplary embodiment, the patterned device layer 1130 is characterized by a first width W1 at the interface between the patterned device layer 1130 and the anticorrosion layer 1129, and a second width W2 at the interface between the patterned device layer 1130 and the substrate 1102. It should be noted that the etching mask 1128 has a width W3 intended by this disclosure, which is greater than, less than, or equal to the width W2.

[0058] An exemplary measure of the degree of undercut is the etch factor F, which is the ratio of the difference in width between the widest and narrowest parts of the patterned device layer feature to the height of the patterned device layer feature. Thus, the etch factor F is defined as H / X (wherein H is the height of the line (H) and X is equal to (W2-W1) / 2, i.e., the difference between the base width (W2) and the top width (W1) divided by 2). Figure 11 schematically illustrates the relationship between H and X. Exemplary values ​​of the etch factor F of the patterned device layer features of this disclosure are discussed below with reference to Examples 1-3. As a non-limiting example, the device layer features associated with devices manufactured by various exemplary embodiments of this disclosure may exhibit an etch factor F greater than 2, greater than 5, greater than 7, or greater than such, for example, greater than 10, greater than 20, etc. In further embodiments, the etch factor F of a conductive feature with sidewalls approaching a vertical line (i.e., not exhibiting an undercut) is considered to approach infinity as the value of X approaches zero. Measurements of H, W1, and W2 may be performed using various microscopy techniques for measuring surface profiles, cross-sections, and film thicknesses, such as, but not limited to, morphometry, scanning electron microscopy, polarization analysis, and confocal microscopy.

[0059] While not adhering to any particular theory, the inventors believe that during the etching process, portions of the anticorrosion material layer detach from the layer and adhere to and / or adsorb to the sidewalls of the device layer under the etching mask, thereby reducing undercuts. Figures 12A and 12B illustrate this phenomenon.

[0060] Figure 12A shows a cross-sectional view of device 1200 during an intermediate processing step in a patterning process according to various exemplary embodiments of the present disclosure. As shown, a partially patterned device layer 1205 on a substrate 1202 is undergoing an etching process. Figure 12B shows a magnified view of the portion of Figure 12A at the interface between the sidewall 1232 of the partially patterned device layer 1205 and the corrosion protection layer 1229. As shown in Figure 12B, when device 1200 is exposed to the etchant 1218, portions 1246 of the corrosion protection material constituting the corrosion protection layer 1229 detach from the corrosion protection layer 1229 by partially dissolving the corrosion protection layer, for example, due to the operation of the etchant 1218, and such corrosion protection material then proceeds onto the sidewall 1232, adhering and / or adsorbing. In other words, the presence of the etchant 1218 can facilitate the migration of portions 1246 of the corrosion-preventive material constituting the corrosion-preventive layer 1220 from the corrosion-preventive material layer 1229 to the sidewalls 1232 of the partially patterned device layer 1230 during the etching process. The presence of portions 1246 of the corrosion-preventive material on the sidewalls 1232 then inhibits the corrosion action of the etchant 1218 on the sidewalls 1232, thereby reducing (e.g., reducing or eliminating) the amount of undercuts exhibited in the resulting patterned device layer 1230. In various exemplary embodiments, at least two processes are thought to contribute to these phenomena, one of which involves the corrosion-preventive material dissolving due to the etchant, and another simultaneously occurring process in which the corrosion-preventive material dissolving in the etchant is adsorbed and / or adhered to the sidewalls 1232. In various exemplary embodiments, the speeds of the first and second processes are such that the amount of undercut obtained is reduced (e.g., reduced or eliminated) as the corrosion-resistant material portion 1246 is formed and maintained during the etching process.

[0061] As shown in Figure 12B, in some cases, the portion of the anticorrosion material 1246 adsorbed to the sidewall 1232 may exhibit a substantially tapered shape, in which case the bonded and / or adsorbed layer 1246 of the anticorrosion material exhibits a greater thickness in close proximity to the anticorrosion material layer 1229 and a decreasing thickness along the layer 1246 in the direction away from the anticorrosion material layer 1229 and toward the substrate.

[0062] Figures 13A, 13B, and 13C illustrate additional embodiments of the process in which particles 1348 of the anticorrosion material may detach from the anticorrosion layer 1329 and adhere to and / or adsorb onto the sidewalls 1332 of the partially patterned device layer 1305 of the device 1300. Figures 13B and 13C show enlarged views of the interface between the anticorrosion material layer 1329 and the sidewalls 1332 of the partially patterned device layer. As shown in Figure 13B, particles 1348 of the anticorrosion material detach from the anticorrosion material layer 1306. In Figure 13C, the detached particles 1348 adhere to and / or adsorb onto the sidewalls 1332 of the partially patterned device layer 1305. The detached particles 1348 may adhere to and / or adsorb onto the sidewalls 1332 of the pattern, which generally decreases in thickness in the direction away from the anticorrosion material layer 1329. In various cases, the dissociated particles 1348 may adsorb and / or adhere to the sidewall 1332 in a substantially uniform pattern, a substantially random pattern, or some other pattern. The presence of particles 1348 on the sidewall 1332 may inhibit the operation of the etchant 1318 and reduce (e.g., reduce or eliminate) undercuts that occur on the partially patterned device layer 1305 during the etching process. As already mentioned with respect to Figure 12, in various exemplary embodiments, at least two processes are thought to contribute to these phenomena, in which one process the protective material is dissolved by the etchant, and in another simultaneously occurring process the dissolved protective material is adsorbed and / or adhered to the sidewall 1332, and in various embodiments, the speed of the first and second processes is such that portions of the protective material 1346 are formed and maintained during the etching process such that the amount of undercuts observed is reduced (e.g., reduced or eliminated).

[0063] Figure 14 is a flowchart illustrating an exemplary embodiment of a workflow 1400 for forming a device, for example, an electrical or optical component or device, as provided in this disclosure, for example. In 1402, an unpatterned device layer is prepared on a substrate. For example, an unpatterned device layer, such as a conductive coating, is laminated or otherwise deposited on the electrically insulating surface of the substrate. In 1404, an undercut-resistant etching mask is formed by depositing an anticorrosion layer on the unpatterned device layer and depositing an etching mask on the anticorrosion material. For example, a liquid primer ink containing an anticorrosion material is blanket-coated onto the substrate and then dried to form an anticorrosion primer layer, and a liquid etching mask ink is printed onto the anticorrosion primer layer and then dried to form an etching mask. Together, the primer layer and the etching mask form an undercut-resistant etching mask. The undercut-resistant etching mask may include a corrosion protection layer (e.g., corrosion protection layers 629, 729, 829, 929, 1129, 1229, or 1329, etc.) and an etching mask (e.g., etching masks 628, 728, 828, or 928, etc.), as discussed in the exemplary embodiments above. The primer layer and the liquid etching mask ink may interact as described above to form a two-component material. The primer layer and the liquid etching mask ink may interact to effectively fix or solidify the ink on the primer surface as described above. In 1406, wet etching is performed to remove areas of the unpatterned device layer not covered by the etching mask (i.e., exposed portions of the unpatterned device layer). The wet etching is performed for a duration sufficient to remove the exposed portions of the unpatterned device layer, thereby leaving the patterned device layer corresponding to the features covered by the etching mask. In 1408, the etching mask is removed by immersing the device in a stream of a stripping fluid designed to dissolve and thereby remove the etching mask, or by spraying the stream onto the device, in order to expose the patterned device layer obtained on the device.In various further embodiments, the stripping process also removes the protective layer beneath the etching mask.

[0064] Figure 15 is a flowchart illustrating in more detail an exemplary embodiment of workflow 1500 for forming an undercut-resistant etching mask, as discussed in relation to 1404 above, on a substrate according to the present disclosure. In 1502, an anticorrosion layer, such as anticorrosion layers 629, 729, 829, 929, 1129, 1229, or 1329, is formed on a substrate having an unpatterned device layer. In the embodiment of Figure 15, the anticorrosion layer is formed as a blanket coating (i.e., an unpatterned layer) on the entire surface of the unpatterned device layer. In 1504, an etching mask, such as an etching mask 628, 728, 828, or 928, is formed on the surface of the anticorrosion layer by blanket coating. In 1506, the etching resist material is directly exposed or photoexposed, such as by exposure to create a pattern of UV light, as schematically discussed above in relation to Figures 2A-2C. In step 1508, the etching resist material is developed to form a patterned etching mask, for example, by removing the etching resist material that has not been exposed to UV light (in the case of a negative process) or that has been exposed to UV light (in the case of a positive process).

[0065] Figure 16 is a flowchart illustrating another exemplary embodiment of workflow 1600 for forming an undercut-resistant etching mask on a substrate according to the present disclosure. In 1602, an anticorrosion layer (e.g., anticorrosion layers 629, 729, 829, 929, 1129, 1229, or 1329, etc.) is formed on a substrate having an unpatterned device layer, with a blanket coating on the unpatterned device layer. In 1604, a patterned etching mask (e.g., etching mask 628, 728, 828, or 928, etc.) is prepared on the unpatterned anticorrosion coating.

[0066] Figure 17 is a flowchart illustrating another exemplary embodiment of the workflow 1700 for forming a device according to the present disclosure. In 1702, an unpatterned device layer, such as a copper film, is laminated onto the electrically insulating surface of the substrate, for example, but not limited to these. In 1704, a protective layer (e.g., protective layers 629, 729, 829, 929, 1129, 1229, or 1329) is formed by blanket coating on the copper film. In 1706, an etching mask (e.g., etching resist mask 628, 728, 828, or 928) is prepared by printing a liquid etching resist ink in a desired pattern onto the blanket-coated protective material, and then drying the liquid to form the etching mask. In 1708, spray wet etching is performed to etch areas of the copper film not covered by the etching mask material. In 1710, the etching mask is peeled off from the rest of the copper film to expose the formed conductive features. In various embodiments, the corrosion-resistant layer is a primer layer, and the liquid etching resist ink may be applied to the surface in the form of droplets delivered by an inkjet nozzle. Upon contact with the primer surface, such droplets are immobilized or "solidified" in place shortly (e.g., in about microseconds) due to a chemical reaction induced by the interaction between the etching resist ink and the primer layer, for example, but not limited to these droplets. Thus, as described above and in International Publication Nos. WO2016 / 193978 A2 and WO2016 / 025949 A1, further translation or spreading of the ink droplets on the primer surface is greatly reduced or completely stopped. In various embodiments, the primer layer and the liquid etching mask ink interact to form a two-component etching mask material.

[0067] Figure 18 shows a block diagram of an apparatus 1800 for producing a device according to an embodiment of the present disclosure. The apparatus 1800 may include a housing 1802. In various exemplary embodiments, the housing 1802 may be configured to provide ambient particle filtration, relative humidity control, temperature control, or other process condition control within the processing environment. The apparatus 1800 may include a first substrate transfer mechanism 1804 and a substrate input unit 1806 configured to receive a substrate from the first substrate transfer mechanism 1804. The substrate may include an unpatterned device layer such as substrates 602, 702, 802, or 902, and unpatterned device layers 604, 704, 804, or 904, as discussed in relation to Figures 6A-9C. The first deposition module 1808 is configured to deposit a first layer, such as corrosion protection layers 629, 729, 829, 929, 1129, 1229, or 1329, as discussed in relation to Figures 6A-9C and 11-13C, on a non-patterned device layer, and the first deposition module 1808 may include a portion for depositing the first material onto the substrate and a portion for further processing the deposited first material, for example, by drying, curing, or otherwise processing the first material to form a corrosion protection layer. The second deposition module 1812 is configured to deposit an etching mask, such as an etching mask 628, 728, 828, or 928, as discussed in relation to Figures 6A-9D, on a corrosion protection material layer. The second deposition module 1812 may include a portion for depositing the second material onto the substrate and a portion for further processing the deposited second material, for example, drying, curing, developing, light exposure, laser direct writing, or other processing, so that an etching mask is formed. The apparatus 1800 may include a substrate output unit 1820 for providing the substrate to a second substrate transfer mechanism (not shown). The first substrate transfer mechanism 1804 may transfer the substrate from a prior processing module or apparatus to the apparatus 1800, and the second substrate transfer mechanism may transfer the substrate to the next processing module or apparatus.

[0068] In various exemplary embodiments, the first deposition module 1808 and the second deposition module 1812 may be configured to deposit material by methods such as inkjet printing, spraying, lamination, spin coating, or any other deposition method including, but not limited to, any of the deposition methods described above.

[0069] In some exemplary embodiments, the apparatus includes a substrate cleansing module 1807 configured to receive a substrate from a substrate input unit 1806, clean the substrate, and transfer the substrate to a first deposition module 1808. In some exemplary embodiments, the first deposition module 1808 and the second deposition module 1812 may be a single module. In some exemplary embodiments, the apparatus 1800 includes an etching module 1816 configured to etch material from an unpatterned device layer not protected by an etching mask, and a stripping module 1818 configured to remove the etching mask from the substrate after etching the material from the unpatterned device layer on the substrate.

[0070] Figure 19 shows an exemplary workflow 1900 according to another embodiment of the present disclosure. In 1902, a primer layer containing a first reactive component is deposited on a metal surface, such as an unpatterned device layer such as copper foil. The primer layer may be an anticorrosion layer such as the anticorrosion layers 629, 729, 829, 929, 1129, 1229, or 1329 associated with the above embodiments. In 1904, a two-component etching resist mask is prepared by printing a liquid etching resist ink containing a second composition containing a second reactive component onto the primer layer as an image. The two-component material obtained from the interaction of the etching resist inks may include, for example, etching masks such as 628, 728, 828, or 928 described in relation to the above embodiments. The second composition may contain a second reactive component that is capable of undergoing a chemical reaction with the first reactive component. In various embodiments, the etching resist ink may be applied to the surface in the form of droplets delivered by an inkjet nozzle, and upon contact with the primer surface, such droplets may soon (e.g., in microseconds) be fixed in place or "solidified" due to a chemical reaction induced by the interaction between the etching resist ink and the primer layer, for example, but not limited to, and thus further translation or spreading of the ink droplets on the primer surface is greatly reduced or completely stopped, as described above and in International Publication Nos. WO2016 / 193978 A2 and WO2016 / 025949 A1. In 1906, the unmasked portion of the primer layer (i.e., the portion of the primer layer not covered by the etching mask) is removed before or during the etching process. In 1908, the unmasked portion of the metal surface is etched to form a patterned device layer such as the patterned device layer 630, 730, 830, 930, 1130, 1230, or 1330 discussed in relation to the above embodiments. In step 1910, the etching resist mask is removed to expose the patterned device layer. [Examples]

[0071] (Examples 1-3) The comparative examples below were conducted to demonstrate the reduction in undercuts achieved using the embodiments of this disclosure compared to conventional processes that do not utilize corrosion inhibitors.

[0072] In Examples 2 and 3, detailed below, the polyimine-based active material composition was first deposited onto the top of an FR4 copper-clad plate having a copper thickness of 1 / 2 oz (17 μm) using an Epson Stylus 4900 inkjet printer. An etching resist mask was then deposited on top of the polyimine layer. The aqueous etching resist composition was prepared using 10% propylene glycol as a wetting agent, 1% (w / w) 2-amino-2-methylpropanol as an ion exchanger, 0.3% (w / w) BYK 348 supplied by BYK as a surfactant, and 2% (w / w) Bayscript BA cyanide as a colorant. The etching resist solution further contained 24% Joncryl 8085 styrene-acrylic resin solution as an anionic etching resist. In the following description, % (w / w) is a measure of the concentration of a substance as a weight percentage relative to the weight of the composition. The printed samples were dried at 80°C. Copper from unprotected exposed zones was etched away using an etchant bath containing an acidic etching solution. The etching resist mask was removed by immersing the etched plate in a 1% (w / w) NaOH aqueous solution at 25°C, then washing the FR4 copper plate with water and drying it using air at 25°C. In Example 1, a different sample was prepared without the underlying working material layer.

[0073] (Example 1) The etching resist pattern was printed on the upper surface of an uncoated copper FR4 plate with a copper thickness of 1 / 2 Oz (17 μm) using an Epson Stylus 4900 inkjet printer. Refer to Figure 20, which shows a micrograph of the cross-section of the copper wire sample prepared in Example 1. The aqueous etching resist composition was prepared using 10% propylene glycol as a wetting agent, 1% (w / w) 2-amino-2-methylpropanol as an ion exchanger, 0.3% (w / w) BYK348 supplied by BYK as a surfactant, and 2% (w / w) Bayscript BA cyanide as a colorant. The etching resist solution further contained 24% Joncryl 8085 styrene acrylic resin solution as an anionic etching resist reactive component. Drying, etching, and removal of the etching resist were carried out as described above. As can be seen from Figure 20, the gradient of the copper sidewall is relatively high. The relevant dimensions of the formed conductive features were measured, and the etch factor was calculated to be 1.5.

[0074] (Example 2) An etching resist pattern was printed onto the upper surface of a copper FR4 plate coated with a polyimine-based coating. The polyimine aqueous solution was prepared as a 0.3% (w / w) mixture containing a 10% (w / w) aqueous solution of LUPASOL G100 (polyethyleneimine with a molecular weight of 5000) supplied by BASF, 10% (w / w) propylene glycol, 10% n-propanol, and TEGO 500 supplied by Evonik Industries. The polyimine solution was applied using an Epson Stylus 4900 inkjet printer. The polyimine coating was left to dry at room temperature, resulting in a completely transparent and uniform coating with a dry thickness of 0.075 μm that covered the entire surface of the plate without crystal formation. The etching resist composition was printed onto the coated copper plate using the process and materials detailed above. The relevant dimensions of the formed conductive features were measured, and the etch factor was calculated to be 2.5.

[0075] (Example 3) An etching resist pattern was printed on the upper surface of a copper FR4 plate coated with a polyimine-based coating. Refer to Figure 21, which shows a micrograph of a cross-section of a copper wire sample prepared according to Example 3 of the embodiments of this disclosure. The polyimine-based coating was applied to the upper surface of the FR4 plate using an Epson Stylus 4900 inkjet printer. The polyimine solution was prepared as a 0.3% (w / w) mixture containing a 10% (w / w) aqueous solution of LUPASOL HF (polyethyleneimine with a molecular weight of 25,000) supplied by BASF, 10% (w / w) propylene glycol, 10% n-propanol, and TEGO 500 supplied by Evonik Industries. The coated plate was left to dry at room temperature, resulting in a completely transparent and uniform coating with a dry layer 0.075 μm thick covering the entire surface without crystal formation.

[0076] The etching resist composition was prepared as detailed in Example 1. Etching of unmasked copper and removal of the etching resist mask were carried out as described with respect to Example 1. As shown in Figure 21, the sidewall gradient of the copper wire is significantly smaller than that of the sample prepared without the undercut exclusion layer shown in Figure 20. The relevant dimensions of the formed conductive features were measured, and the etch factor was measured and found to be 7.5.

[0077] Table 1 below summarizes some of the characteristics of the results from the three examples.

[0078] [Table 1-1]

[0079] The comparative examples below were conducted to demonstrate an improvement in etching mask formation using a primer layer and inkjet-printed etching resist ink, in which contact with the primer layer causes one or more reactions to occur between the components of the primer layer and the etching resist ink, forming a two-component etching mask material in which droplets of etching resist ink are rapidly fixed or solidified (e.g., in about microseconds), and the subsequent spreading and / or translation of such droplets is greatly reduced. (Examples 4-12)

[0080] Using an Epson Stylus 4900 inkjet printer, exemplary etching resist compositions (second compositions as described herein) were printed onto FR4 copper-clad plates having thicknesses of 1 / 2 Oz, 1 / 3 Oz, and 1 Oz. In some cases, using an Epson Stylus 4900 inkjet printer, copper was first coated with a fixing composition (first composition as described herein) to form a fixing layer, and thereon, the etching resist compositions were selectively printed according to a predetermined pattern. In the following description, %(w / w) is a measure of the concentration of a substance as a weight percentage relative to the weight of the composition. Copper from the unprotected-by-exposed zones was etched off using an etchant bath containing a ferric chloride etchant solution supplied by Amza [pernix 166], with a Baume degree intensity of 42°. Etching was performed in a Spray Developer S31 supplied by Walter Lemmen GMBH at a temperature of 35°C for 3 minutes. The etching resist mask was removed by immersing the etched plate in a 1% (w / w) NaOH aqueous solution at 25°C, then washing the FR4 copper plate with water and drying it with air at 25°C. In some experiments, the copper plates were also etched using industrial etching units, including hyper and super etching units manufactured by Universal or Shmidth, which contained copper chloride solutions for etching unprotected copper.

[0081] (Example 4) An etching resist composition was printed onto the upper surface of an uncoated copper FR4 plate (comparative data). The etching resist composition (second composition) was prepared with 10% propylene glycol, 1% (w / w) 2-amino-2-methylpropanol, 0.3% (w / w) BYK 348 supplied by BYK, and 2% (w / w) Bayscript BA cyanide. These materials were dissolved in water containing 24% Joncryl 8085 styrene-acrylic resin solution as an anionic reactive component. Epson style An etching resist mask was produced by printing an etching resist composition onto an FR4 copper-clad plate with a thickness of 1 / 2 oz using a Lath 4900 inkjet printer. The thickness of the dried etching resist was 5 microns.

[0082] Visual inspection of the etching mask revealed that the printed pattern exhibited extremely poor print quality, with very insufficient edge resolution, disconnections, and severe short circuits between lines.

[0083] (Example 5) The etching resist composition was prepared as detailed in Example 4. The primer or fixing composition was prepared as a mixture of 10% (w / w) aqueous solution of LUPASOL PR8515 supplied by BASF (polyethyleneimine as the cationic reactive component), 10% (w / w) propylene glycol, 10% n-propanol, and 0.3% (w / w) TEGO 500 (foam-inhibiting substrate wetting additive) supplied by Evonik Industries.

[0084] An FR4 copper plate was coated using an Epson Stylus 4900 inkjet printer. The coated plate was left to dry at room temperature, resulting in a perfectly transparent and uniform coating with a 0.3 μm thick dry layer covering the entire surface, without any crystal formation. An etching resist composition was printed onto the coated copper plate using the Epson Stylus 4900 inkjet printer and dried at 80°C to produce a two-component etching resist mask. Visual inspection of the etching mask showed better print quality than in Example 4, but still exhibited relatively poor print quality for thicker lines and short circuits between lines. Etching of the unmasked copper and removal of the etching resist mask were carried out as detailed in Example 4. The wiring pattern generated after the etching process had the same image as the etching resist mask, with the same thickness of lines and short circuits between lines. It should be noted that in certain application examples, the print quality shown in Example 5 may be sufficient.

[0085] (Example 6) The etching resist composition was prepared as detailed in Example 4. The fixing composition was prepared as detailed in Example 5, except that 0.3% (w / w) TEGO500 was replaced with 0.3% (w / w) TEGO 500 containing 13% (w / w) concentrated HCl.

[0086] An FR4 copper plate was coated with a fixing composition using an Epson Stylus 4900 inkjet printer, as detailed in Example 5, and after drying, a coating layer was formed as detailed in Example 5. Similar to Example 5, an etching resist composition was inkjet printed onto the coated copper plate and dried at 80°C to produce a two-component etching resist mask. The etching resist pattern demonstrated high print quality, with well-defined fine lines reduced to a thickness of 2 mm, sharp edges, and no breaks. Etching of the unmasked copper and removal of the etching resist mask were carried out as detailed in Example 4. The wiring pattern generated by the etching and stripping process demonstrated a well-defined pattern with fine lines reduced to a width of 15 microns, sharp edges, and no breaks.

[0087] (Example 7) A two-component reaction etching resist composition was printed onto a copper surface coated with a reactive cation composition containing hydrochloric acid (HCl). The etching resist composition was prepared as detailed in Example 4. The fixing composition was prepared as a mixture of 10% (w / w) aqueous solutions of Styleze W-.

[0088] 20% (supplied by ISP as a 20% aqueous polymer solution), 0.1% BYK 348, and 13% (w / w) concentrated HCl.

[0089] A 0.4 μm thick dry layer was created by covering an F4F copper plate with a fixing composition using a Mayer rod. When the coated plate was left to dry, a completely transparent coating was obtained across the entire copper surface without crystal formation. Similar to Example 5, an etching resist composition was inkjet printed onto the coated copper plate and dried at 80°C to produce a two-component etching resist mask.

[0090] The etching resist pattern demonstrated high print quality, with well-defined fine lines reduced to 2 mm in width, sharp edges, and no breaks. Residue of the fixed layer not covered by the etching resist composition was cleaned by immersing the board in water for 2 minutes at 25°C and drying at 80°C. Etching of exposed copper and removal of the etching resist mask were carried out as detailed in Example 4. The wiring pattern on the board demonstrated well-defined fine lines with sharp edges, reduced to a width of 2 mil, and no breaks.

[0091] (Example 8) An etching resist composition printed on a copper surface coated with a two-component reactive cation composition containing hydrochloric acid (HCl). The etching resist composition was prepared as detailed in Example 4.

[0092] The bonding composition was prepared as a mixture of a 10% (w / w) aqueous solution of Lupasol HF (supplied by BASF as a 56% polymer aqueous solution) and 0.1% BYK 348 containing 13% (w / w) concentrated HCl.

[0093] A 1 μm thick dry layer was created by covering an FR4 copper plate with a fixing composition using a Mayer rod. When the coated plate was left dry, a completely transparent coating was obtained across the entire copper surface without crystal formation. Similar to Example 5, an etching resist composition was inkjet printed onto the coated copper plate and dried at 80°C to produce a two-component etching resist mask.

[0094] The etching resist pattern demonstrated high print quality with well-defined, fine lines reduced to 2 mils, containing sharp edges and free from breaks. Residue of the fixed layer not covered by the etching resist composition was cleaned by immersing the board in water at 25°C for 3 minutes and drying at 80°C. Etching of exposed copper and removal of the etching resist mask were carried out as detailed in Example 4. The wiring pattern on the board demonstrated well-defined, fine lines with a width reduced to 2 mils, containing sharp edges and free from breaks.

[0095] (Example 9) Two-component reaction: An etching resist composition printed on a copper surface coated with a reactive cation composition containing hydrochloric acid (HCl). The etching resist composition was prepared as detailed in Example 5. The fixing composition was prepared as a mixture of 10% (w / w) aqueous solution of Lupasol PN50 (supplied by BASF as a 49% polymer aqueous solution) and 0.1% BYK348 containing 13% (w / w) concentrated HCl.

[0096] A 1 μm thick dry layer was created by coating an FR4 copper plate with a fixing composition using a Mayer rod. When the coated plate was left dry, a completely transparent coating was obtained across the entire copper surface without crystal formation. Similar to Example 5, etching resin was used. The resist composition was inkjet printed onto a coated copper plate and dried at 80°C to produce a two-component etching resist mask.

[0097] The etching resist pattern demonstrated high print quality, with well-defined fine lines reduced to 2 mm in width, sharp edges, and no breaks. Residue from the fixed layer was cleaned as described in Example 8. Etching of exposed copper and removal of the etching resist mask were carried out as detailed in Example 1. The wiring pattern on the board demonstrated well-defined fine lines reduced to 2 mil in width, with sharp edges and no breaks.

[0098] (Example 10) An etching resist composition printed on a copper surface coated with a two-component reactive composition containing citric acid. The etching resist composition was prepared as detailed in Example 4. The fixing composition was prepared as a mixture of a 10% (w / w) aqueous solution of citric acid, 25% (w / w) propylene glycol, and 0.3% (w / w) TEGO 500 (foam-inhibiting substrate wetting additive) supplied by Evonik Industries.

[0099] An FR4 copper plate was coated with a bonding composition using an Epson Stylus 4900 inkjet printer. The coated plate was left to dry at room temperature, resulting in a completely transparent and uniform coating with a 0.3 μm thick dry layer covering the entire surface without crystal formation. Similar to Example 5, an etching resist composition was inkjet printed onto the coated copper plate and dried at 80°C to produce a two-component etching resist mask.

[0100] The etching resist pattern demonstrated high print quality, with well-defined, fine lines reduced to 2 mils, sharp edges, and no breaks. Etching of exposed copper and removal of the etching resist mask were carried out as detailed in Example 4. The wiring pattern on the board demonstrated well-defined, fine lines reduced to 2 mils in width, containing sharp edges and no breaks.

[0101] (Example 11) A coating composition containing a two-component reaction and etching resist composition was prepared as detailed in Example 4. The fixing composition was prepared as a mixture of 2.5% (w / w) aqueous solution of Zn(NO3)2, 3.75% (w / w) calcium acetate, 0.2% (w / w) Capstone 51, 5% (w / w) n-propanol, and 5% (w / w) Lupasol FG (supplied from BASF).

[0102] A 0.5 μm thick dry layer was created by covering an FR4 copper plate with a bonding composition using a Mayer rod. When the coated plate was left dry, a completely transparent coating was obtained across the entire copper surface without crystal formation. Similar to Example 5, an etching resist composition was inkjet printed onto the coated copper plate and dried at 80°C to produce a two-component etching resist mask.

[0103] Similar to Example 5, an etching resist composition was inkjet printed onto a coated copper plate and dried at 80°C to produce a two-component etching resist mask.

[0104] The etching resist pattern demonstrated high print quality, with well-defined fine lines reduced to 2 mils, sharp edges, and no breaks. Etching of exposed copper and removal of the etching resist mask were carried out as detailed in Example 4. The wiring pattern demonstrated well-defined, thin lines with widths reduced to 2 mils, containing sharp edges and without breaks.

[0105] (Example 12) The etching resist composition was prepared as a mixture of 8% (w / w) aqueous PVA solution, 24% Joncryl 8085 styrene acrylic resin solution (supplied as a 42% aqueous polymer solution), and 1.5% 2-amino-2-methylpropanol.

[0106] The fixing composition was prepared as follows: 2% (w / w) Basacid Red 495, 10% (w / w) propylene glycol, 10% n-propanol, 0.3% (w / w) TEG0500, 10% (w / w) Lupasol G20 (supplied by BASF), and containing 12% (w / w) concentrated HCl. An FR4 copper plate was coated with the etching resist composition using a Mayer rod to create a 2.4 μm thick dry layer. The coated plate was left to dry, resulting in a completely transparent coating across the entire copper surface without crystal formation. The fixing composition was inkjet printed onto the coated copper plate and dried at 80°C to produce a two-component etching resist mask.

[0107] Similar to Example 5, an etching resist composition was inkjet printed onto a coated copper plate and dried at 80°C to produce a two-component etching resist mask.

[0108] The etching resist pattern demonstrated high print quality, with well-defined fine lines reduced to 2 mils, sharp edges, and no breaks. Residue of coatings not covered by the etching resist ink was cleaned by immersing the board in a 1% (w / w) NaHCO3 aqueous solution at 25°C for 30 seconds, and then dried at 80°C. Etching of exposed copper and removal of the etching resist mask were carried out as detailed in Example 4. The wiring pattern on the board demonstrated well-defined fine lines with sharp edges and no breaks, reduced to a width of 2 mils. Cationic composition (adhesion-reactive component)

[0109] Non-limiting examples of cationic reactive components (adhesion reactive components) may include polyamides, e.g., polyethyleneimine, divalent metal salts, both organic and inorganic acids, vinylpyrrolidone heteropolymers, dimethylaminopropyl methacrylamide; methacryloylaminopropyl lauryldimethylammonium chloride, polyquaternary amines, and polyamines, either in their natural form or as ammonium salts.

[0110] The thickness of the dry bonded layer may be as thin as approximately 0.01 microns. Typical desired thicknesses for the dry layer can vary from 0.025 to 5 microns.

[0111] The cationic composition (the first composition) may contain additional components adapted to suit the method of adhesion of the dry layer and the desired width. The composition may have a viscosity suitable for spraying or inkjet printing, for example, less than 60 centipoise at ambient temperature, or a viscosity between 3 and 20 cP (centipoise), respectively. The composition may have a higher viscosity when a different coating method is applied.

[0112] In some embodiments, an acidic solution may be added to the first solution to increase the reactivity of the first layer with respect to the copper layer 320 and its reactivity with respect to the etching resist or fixing layer. In some embodiments, the first layer may be further developed, for example, with water, before the copper etching process. In some embodiments, the attached first layer may be dried before the second layer is attached. The as-dried layer may mainly contain the first reactive material. The first layer may be dried using any known drying method.

[0113] Some non-limiting examples of the first reactive component (e.g., a bonding component) and the first composition (e.g., a bonding composition, a cationic composition) are listed in Table 1. [Table 1-2] Anionic composition (etching resist polymer component)

[0114] In some embodiments, the second reactive component (e.g., a polymer component) may be an etching-resistant component (resistant to metal etching solutions). The second reactive component may include polyanionic active groups such as acrylates, styrene acrylates, phosphates, and sulfonates. Droplets of etching resist ink attached to the upper surface of the first (e.g., fixed) layer can be immobilized and fixed to the copper surface due to a chemical reaction between the first reactive material (containing polycations) and the second reactive material (containing polyanions). Since the fixation is very rapid (within the range of microseconds), the dimensions of the printed pattern are similar to the dimensions of the required pattern. The compound formed by the reaction of the first reactive material and the second reactive material (both soluble in water) should be insoluble in copper etching solutions.

[0115] The second composition is an inkjet with a spray temperature of less than 60 cP, for example, 3 to 20 cP. The composition may have a viscosity suitable for printing. The composition may have a higher viscosity if a different coating method is applied. In some embodiments, the second composition may contain 20% (w / w) or less of the reactive component so that the required viscosity is maintained. In some embodiments, the polyanionic reactive component (etching resist polymer) when dissolved in the composition may have a maximum molar weight of 5000 (e.g., the polymer may have relatively short chains). In some embodiments, the etching resist polymer may have a higher molar weight resulting in a composition in the form of a polymer emulsion or dispersion. The second reactive component may have a high acid value, for example, having more than 100 reactive anionic groups per gram of polymer. For example, the etching resist polymer according to embodiments of the present invention may have more than 200, 240, 300, or more reactive anionic groups in each chain.

[0116] Table 2 lists some non-limiting examples of the second reactive component (etching-resistant component) and the second composition (etching-resistant composition, anionic composition). [Table 2]

[0117] This description and accompanying drawings, illustrating exemplary embodiments, should not be construed as limiting. Various mechanical, compositional, structural, and operational modifications, including equivalents, may be made without departing from the scope of this description and claims. In some cases, well-known structures and techniques are not illustrated or described in detail so as not to obscure this disclosure. Similar reference numerals in two or more drawings represent the same or similar elements. Furthermore, elements and their related features described in detail with reference to one embodiment may, whenever practical, be included in other embodiments that are not specifically illustrated or described. For example, if an element is described in detail with reference to one embodiment but not with reference to a second embodiment, it may nevertheless be claimed that the element is included in the second embodiment.

[0118] For the purposes of this specification and the accompanying claims, unless otherwise indicated, all numerical values ​​representing quantities, percentages, or proportions, and other numerical values ​​used herein and in the claims, should be understood to be modified in all cases by the term “about” to the extent that they are not yet modified in that way. Therefore, unless otherwise indicated, numerical parameters described in the following specification and the accompanying claims are approximations, which may vary depending on the desired properties to be obtained. At the very least, without intending to limit the application of the principle of equivalents to the claims, each numerical parameter should be interpreted in light of the reported number of significant figures and by applying common rounding techniques.

[0119] It should be noted that, as used herein and in the appended claims, the use of the singular forms “a,” “an,” and “the,” and any singular form of any word, includes multiple referents unless explicitly and obviously limited to one. The term “includes” and its grammatical variations as used herein are non-restrictive, and therefore the enumeration of items in a list does not exclude any other similar items that may be substituted for or added to the enumerated items.

[0120] Furthermore, the terminology used in this description is not intended to limit this disclosure. For example, spatial terms—such as “beneath,” “below,” “lower,” “above,” “upper,” “proximate,” and similar—may be used to describe the relationship of one element or feature to another, as shown in the figures. These spatial terms shall encompass different locations (i.e., places) and orientations (i.e., rotational orientations) of the device in use or operation, in addition to the positions and orientations shown in the figures. For example, if the device in the figure is inverted, an element described as “below” or “directly below” another element or feature would be considered “above” or “over” that other element or feature. Thus, the exemplary term “below” can encompass both upper and lower positions and orientations. The device may be oriented in other ways (rotated 90 degrees or otherwise), and the spatial descriptions used herein shall be interpreted accordingly.

[0121] Further modifications and alternative embodiments will be made apparent to those skilled in the art in view of the disclosure herein. For example, devices and methods may include additional components or steps omitted from the figures and descriptions for clarity of operation. This description should therefore be interpreted as merely illustrative and intended to teach those skilled in the art a general method for carrying out the teachings of the present invention. It should be understood that the various embodiments illustrated and described herein are to be interpreted as illustrative. Elements and materials, as well as the arrangement of such elements and materials, may be substituted for those illustrated and described herein, parts and steps in workflows and processes may be in alternating order, certain features of the teachings of the present invention may be used independently, all of which can be made apparent to those skilled in the art after benefiting from the description herein. Modifications may be made in elements described herein without departing from the spirit and scope of the teachings of the present invention and the following claims.

[0122] Various exemplary embodiments described herein describe the manufacture of PCBs, but those skilled in the art will know that they can be manufactured using similar etching and metallic or conductive line patterning techniques. It should be understood that other electrical and optical devices or components are included within the scope of this disclosure and claims, and that PCBs are discussed as one non-limiting exemplary application. Other devices and components that may be manufactured by exemplary embodiments herein include, but are not limited to, microchips, electronic displays, solar cells, and other electronic, optical, or other devices and components.

[0123] The specific examples and embodiments described herein are not limiting, and modifications to the structure, dimensions, materials, and methods may be made without departing from the teachings of the invention. Other embodiments provided herein will be apparent to those skilled in the art from the specifications and exercises of this disclosure. The specifications and examples are to be considered merely illustrative, and the following claims are intended to represent the maximum extent of those, including their equivalents under applicable law.

Claims

1. A method for fabricating a device patterned with one or more conductive features, the method comprising: The steps include depositing a conductive layer on the electrically insulating surface of the substrate, The steps include depositing a first layer containing one or more cationic components on the conductive layer, A step of depositing a second layer containing one or more anionic components on the first layer, wherein the second layer and the first layer react to form a two-component etching mask in a pattern that produces a covering portion of the conductive layer and an exposed portion of the conductive layer, and the covering portion is positioned to correspond to the one or more conductive features of the device, The steps include: performing a wet etching process to remove the exposed portion of the conductive layer from the substrate, thereby forming the conductive characteristics; A method comprising the step of removing the two-component etching mask to expose the conductive characteristics of the device, A method wherein the first layer, the second layer, or both are made of a polymer, and the first layer comprises a hydrazine group.

2. A method for fabricating a device patterned with one or more conductive features, the method comprising: The steps include forming a first layer containing one or more cationic components on a conductive layer of a substrate, The steps include: depositing a second layer on the first layer, forming a two-component etching mask in a pattern where the second layer and the first layer react to produce a covering portion of the conductive layer and an exposed portion of the conductive layer, and positioning the covering portion at a location corresponding to one or more conductive features of the device; The steps include: performing a wet etching process to remove the exposed portion of the conductive layer from the substrate to form the conductive features; A method comprising the step of removing the two-component etching mask to expose the conductive characteristics of the device, The first layer comprises a hydrazine group.

3. A method for fabricating a device patterned with one or more conductive features, the method comprising: The steps include depositing a conductive layer on the electrically insulating surface of the substrate, The steps include depositing a first layer containing one or more cationic components on the conductive layer, A step of depositing a second layer containing one or more anionic components on the first layer, wherein the second layer and the first layer react to form a two-component etching mask in a pattern that produces a covering portion of the conductive layer and an exposed portion of the conductive layer, and the covering portion is positioned to correspond to the one or more conductive features of the device, The steps include: performing a wet etching process to remove the exposed portion of the conductive layer from the substrate, thereby forming the conductive characteristics; A method comprising the step of removing the two-component etching mask to expose the conductive characteristics of the device, A method comprising the first layer, the second layer, or both, being made of a polymer, wherein the first layer comprises an amino acid.

4. A method for fabricating a device patterned with one or more conductive features, the method comprising: The steps include forming a first layer containing one or more cationic components on a conductive layer of a substrate, The steps include: depositing a second layer on the first layer, forming a two-component etching mask in a pattern where the second layer and the first layer react to produce a covering portion of the conductive layer and an exposed portion of the conductive layer, and positioning the covering portion at a location corresponding to one or more conductive features of the device; The steps include: performing a wet etching process to remove the exposed portion of the conductive layer from the substrate to form the conductive features; A method comprising the step of removing the two-component etching mask to expose the conductive characteristics of the device, The first layer comprises an amino acid.

5. A method for fabricating a device patterned with one or more conductive features, the method comprising: The steps include depositing a conductive layer on the electrically insulating surface of the substrate, The steps include depositing a first layer containing one or more cationic components on the conductive layer, A step of depositing a second layer containing one or more anionic components on the first layer, wherein the second layer and the first layer react to form a two-component etching mask in a pattern that produces a covering portion of the conductive layer and an exposed portion of the conductive layer, and the covering portion is positioned to correspond to the one or more conductive features of the device, The steps include: performing a wet etching process to remove the exposed portion of the conductive layer from the substrate, thereby forming the conductive characteristics; A method comprising the step of removing the two-component etching mask to expose the conductive characteristics of the device, A method comprising the first layer, the second layer, or both being made of a polymer, wherein the first layer is a Schiff base.

6. A method for fabricating a device patterned with one or more conductive features, the method comprising: The steps include forming a first layer containing one or more cationic components on a conductive layer of a substrate, The steps include: depositing a second layer on the first layer, forming a two-component etching mask in a pattern where the second layer and the first layer react to produce a covering portion of the conductive layer and an exposed portion of the conductive layer, and positioning the covering portion at a location corresponding to one or more conductive features of the device; The steps include: performing a wet etching process to remove the exposed portion of the conductive layer from the substrate to form the conductive features; A method comprising the step of removing the two-component etching mask to expose the conductive characteristics of the device, The first layer comprises a Schiff base.

7. The method according to any one of claims 1 to 6, wherein the step of depositing the first layer on the conductive layer includes the step of depositing a polymer on the conductive layer.

8. The method according to any one of claims 1 to 6, wherein the step of depositing the second layer includes depositing the second layer on the first layer by blanket coating.

9. The method according to any one of claims 1 to 6, wherein the step of depositing the second layer includes using at least one of inkjet printing, slot die coating, spin coating, or lamination.

10. The method according to any one of claims 1 to 6, wherein the step of depositing the first layer includes using at least one of inkjet printing, slot die coating, spin coating, or lamination.

11. The method according to any one of claims 1 to 6, wherein the thickness of the first layer is in the range of 5 μm to 40 μm.

Images