Transfer of a pattern to a substrate

Abstract

An apparatus and method are disclosed for transferring patterns carried by a web of a deformable plastics material onto substrates. The apparatus comprises a nip defined between at least one nip roller and a backing support through which the substrates are passed simultaneously with the web and by means of which pressure is applied to effect transfer of the patterns from the web to the substrates. In the invention, a web heater and a web tensioner are arranged upstream of the nip, and a control unit is provided for controlling the web heater and the web tensioner in dependence upon data indicative of the lengths and widths of the patterns on the web prior to transfer, or of the patterns on the substrates after transfer, so as to ensure that, after transfer to the substrates, the patterns conform to a desired length and width.

Description

[0001] TRANSFER OF A PATTERN TO A SUBSTRATE

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims Paris Convention priority from Great Britain patent application No. GB 2311276.6 filed on July 21, 2023, the entire disclosures of which are hereby incorporated by reference, as if fully set forth herein.

[0004] FIELD

[0005] The present invention relates to the transfer of patterns from a web to substrates, such as performed in the manufacture of solar cells and circuit boards, wherein the pattern may furthermore be conductive.

[0006] BACKGROUND

[0007] In the manufacture of certain products, there arises a need to apply a substance pattern to a surface of a substrate, the applied pattern being intended to have a function, an ornamental purpose, or both. For example, in the manufacture of solar cells, circuit boards, touch screens and radio frequency identification (RFID) antennas, amongst other items, one may wish to apply to a substrate, according to a desired pattern, a substance that comprises a composition containing particles of an electrically conductive material, and typically a binder maintaining the particles in a desired shape (e.g., pattern of lines, cross-section of lines, etc.) and / or an adhesive which may enhance adherence to the intended substrate or facilitate any functional interaction therewith. The substrate may, for instance, be a semiconductor wafer in the case of a solar cell, or it may be an electrically insulating substrate in the case of a printed circuit board. While such substrates are typically rigid and planar, flexible and / or non-flat (e.g., curved) substrates may also be used. In some cases, for example for an RFID device or when the pattern is ornamental, it may be desired to apply a substance pattern directly onto a three-dimensional item, such as part of the body of a piece of equipment or a decorative article, whereupon the surface may be flat or curved.

[0008] There has previously been proposed by the present Applicant in EP 3826438, which is incorporated herein by reference in its entirety, a method of applying a pattern of electrical conductors to a substrate, which comprises providing a flexible membrane, or web, having a layer made of a conformable plastics polymer, such as a thermoplastic polymer, capable of being embossed or cast. A first surface of the membrane (or front side of the web) has a pattern of grooves formed therein, the pattern corresponding to at least a part of a desired pattern of electrical conductors to be applied to the substrate. A composition is loaded into the grooves of the first surface of the membrane, or may be otherwise deposited thereon, the composition including particles of an electrically conductive material and an adhesive. The loading is performed in filling cycles such that on completion of loading the composition substantially fills the grooves, level with the first surface of the membrane, and parts of the first surface between the grooves are substantially devoid of the composition. The membrane is next contacted with the substrate with the first surface of the membrane facing a desired face of the substrate and pressure is applied to the membrane to cause the composition loaded into the grooves in the first surface of the membrane to adhere to the substrate. Next, the membrane can be separated from the substrate to transfer the composition from the grooves in the first surface of the membrane to the substrate. Energy may later be applied to sinter the electrically conductive particles, to render electrically conductive the pattern of composition transferred to the substrate from the grooves. A similar method is disclosed in EP 3491900 to the Applicant, which is incorporated herein by reference in its entirety.

[0009] In EP 3491902, which is also incorporated herein by reference in its entirety, the Applicant has further proposed an apparatus for transferring a pattern of a transferable composition, such as containing particles of an electrically conductive material and a thermally activatable adhesive, from a surface of such a flexible web to a surface of a substrate. The apparatus comprises respective drive mechanisms for advancing the web and the substrate at the same time through a nip at which the surfaces of the web and the substrate are pressed against one another. A heating station is provided for heating the web and / or the substrate prior to, and / or during, passage through the nip, to a temperature at which the adhesive in the composition is activated when the surfaces are in contact with one another. A cooling station can be used to cool the web after passage through the nip and prior to the web optionally passing through a separating device that peels the web away from the substrate to leave the pattern of composition adhered to the surface of the substrate.

[0010] When employing the above methods and apparatus to apply, for instance, conductive patterns to substrates, it has been found that the dimensions of the patterns after application to the substrates may vary. Not only can the dimensions of transferred patterns vary between different webs carrying the patterns but even patterns carried by the same web can vary in size progressively during the transfer process from the web to the substrates. The variations can be in both the length of the patterns, as measured in the direction of movement of the web through the nip (which can be referred to as an X-direction) and in their width as measured in the transverse direction (which can be referred to as a Y-direction). Such variations may be caused both by conditions during the production of the web carrying the patterns, as well as conditions during the process of transferring patterns from the web to the substrates. Such variations may result in deviations from desired nominal values exceeding tolerable divergences. In such a case, the transferred patterns having non-conforming dimensions may be less able to align properly with the substrates and / or with patterns transferred to the opposite side of the same substrates. Alternatively, or additionally, some deviations from desirable dimensions may adversely affect the appearance and / or function of the transferred pattern.

[0011] OBJECT OF THE INVENTION

[0012] The present invention seeks to mitigate the problem of size variation between patterns applied to different substrates, this problem being particularly significant when the patterns are carried by a flexible web.

[0013] SUMMARY OF THE INVENTION

[0014] In one aspect, the present invention provides an apparatus for transferring patterns carried by a web of a deformable plastics material onto substrates, the apparatus comprising a nip defined between at least one nip roller and a backing support through which the substrates are passed simultaneously with the web and by means of which pressure is applied to effect transfer of the patterns from the web to the substrates, the apparatus being characterized by a web heater and a web tensioner arranged upstream of the nip, and a control unit for controlling the web heater and the web tensioner in dependence upon data indicative of the lengths and widths of the patterns on the web prior to transfer, or of the patterns on the substrates after transfer, so as to ensure that, after transfer to the substrates, the patterns conform to a desired length and width.

[0015] The patterns need not have the exact nominal values of the dimensions desired following transfer to the substrates. The patterns’ dimensions may be within a tolerated deviation therefrom (either in absolute terms, e.g., within 100 micrometer (pm), or in relative terms, e.g., within 1% of ideal length and / or width). In some cases, the relative position of the patterns on the substrates is not critical, provided that the patterns conform to desired dimensions characterizing them, whereas in other cases it can be additionally desired that the patterns be applied within a specific area of the substrates. The desired area within the surface of the substrate can be referred to as the “transfer region”, whereas the area of the substrate where no pattern is to be applied can be called the “no-transfer region”. Generally, the no-transfer regions form margins surrounding at least a part of the perimeter of the pattern, but they may alternatively (or additionally) be regions within the otherwise permitted transfer region. When the patterns on the web need additionally to be aligned with respect to at least one edge of the substrates, dimensions of the substrates can additionally be taken into account or determined by the apparatus so that each pattern can be aligned with each substrate to which it is to be transferred.

[0016] The relative alignment of each pattern with its substrate can be addressed by at least one of: a) a web guide device adapted to actively displace the web upstream of the nip along the Y-direction traverse to its X-direction of movement towards the nip or designed to maintain the web within a laterally predetermined path; b) an alignment device adapted to position inter alia the lateral edges of the substrate (z.e., their Y-position) and / or rotate the substrate to match a skew of the pattern on the web, prior to substrate’s entry into the nip; and c) a speed modifying device adapted to accelerate or decelerate a substrate to ensure the timing of its entry into the nip (z.e., its X-position) coincide with the entry of the web carrying the pattern to be transferred thereupon.

[0017] For instance, the apparatus can be set (e.g., via proper operation of a suitable web guiding device, of the substrate alignment device, and / or of a substrate speed modifier) so that a centroid point of the pattern and of the substrate substantially coincide (or are at a desired separation), whilst the two pass through the nip.

[0018] In some cases, when patterns are to be applied to both sides of a substrate, and the two patterns are to be aligned one with respect to the other, the desired length and width of the first pattern carried by a first web may depend on the length and width of the second pattern carried by a second web. In such a case, at least one of the heating and tensioning of the first and the second web can be set to ensure proper reciprocal alignment. In some embodiments, patterns on distinct webs (sides of the substrate) do not only need to be aligned with one another, but also with the substrate, when particular transfer regions are intended for the applied patterns. In such case, at least one of the webs and the substrate may be aligned relative to one another (for instance, such as aforementioned for the case of a single web serving to apply a pattern on a single side of the substrate). When two webs are used to convey same or different patterns separately for each side of the substrate, the transfer regions on both sides of the substrate need not be the same (e.g., in shape and / or position with respect to the substrate edges).

[0019] In some embodiments of the invention, measurements of the patterns or fiducial markings on the web may be made prior to the patterns reaching the nip at which the patterns are transferred to the substrates, and during the process of transferring the patterns from the web to the substrates, the temperature and tension of the web prior to entering the nip being regulated in dependence upon the measurements.

[0020] In alternative embodiments, measurements may be made of patterns that have been transferred to substrates, and during the process of transferring patterns from the web to further substrates, the temperature and tension of the web prior to entering the nip being regulated in dependence upon the measurements.

[0021] The length of the patterns can be varied by varying the tension of the web upstream of the nip, but such stretching of the web may also reduce its width and therefore the width of the patterns. Heating of the web will soften the web and therefore increase its deformation during passage through the nip, causing both the width and the length of the patterns to increase with increased temperature. By correctly setting both the tension and the temperature of the web prior to reaching the nip in dependence upon measurements taken prior to the web entering the nip, and / or after exiting the nip, the invention can ensure that the patterns are stretched as necessary during the transfer to conform more accurately and consistently to a desired length and width after transfer to the substrates.

[0022] Measurements of the length and width of the patterns may be carried out at the time of manufacture of the web and encoded markings (e.g., a barcode) may be applied to the web during manufacture containing data indicative of the sizes of the patterns. In such an implementation of the invention, the control unit of the apparatus would serve to set the web temperature and tension based on the data read from the web. The encoded markings may provide information of relevance to different variations displayed along the web at a distance of unwinding, the web temperature and tension being modulated so as to be suitable at said distance.

[0023] Alternatively, or additionally, there could be detectable data markings on the web. The data markings on the web may be a measure of the length and width of the patterns on the web in a region adjacent to the markings, or may allow the actual in-line measurements of said dimensions, or they may indicate the optimum web temperature and web tension to be set by the control unit at the time of the transfer of the patterns to the substrates. Such an approach would suffice if maintaining constant temperature and pressure during transfer of the patterns would consistently yield transferred patterns on the substrates of a constant size. However, as mentioned previously, it has been found in practice that size variations can develop progressively during the transfer of patterns from a single web. To compensate for such errors, in an alternative embodiment of the invention, the apparatus comprises sensors to take measurements indicative of the widths and lengths of the patterns on the web at the time of the transfer at a position upstream of the nip.

[0024] It will be appreciated that because the web temperature can only be changed relatively slowly, as compared to the speed at which the web may be fed to the nip (e.g., up to 1 m / sec), it is not possible to use this approach to correct for random variations in the size of the transferred patterns from one pattern to the next on the same web. However, this approach will at least reduce the progressive size changes that have experimentally been found to occur.

[0025] In some embodiments, the sensors may comprise optical sensors for determining the positions of specific markings on the web on opposite lateral sides of the web, the markings being either fiducials distinct from the (e.g., conductive) patterns or elements of the patterns, so as to provide a measurement indicative of the width of the patterns on the web. For illustration, the markings (or elements at corresponding positions in subsequent patterns) can be expected to be ideally at a pre-determined pitch between occurrences repeating along the web.

[0026] The nip may be associated with a shaft encoder capable of measuring the movement of the web through nip. In such an embodiment, the length of web passing through the nip between detection by the optical sensors of consecutive specific markings on the web provides an indication of the length of the patterns on the web.

[0027] In some embodiments, the web heater may be a heated roller located upstream of the nip, but it would alternatively, or additionally, be possible to heat a section of the web by means of a blower or by radiation. It is further possible for at least one of the surfaces which, when engaged, define the nip at which transfer is performed (ie., a nip roller or the backing support) to include a heater.

[0028] In some embodiments, the apparatus is adapted to transfer patterns to both sides of the same substrate. In such a case, the apparatus may include two separate nips, each one for transfer of a particular pattern from a respective web to a specific side. The nips can be constituted of a nip roller and a backing support or of two nip rollers aligned one with the other. Alternatively, the two patterns may be transferred to each side of the substrate from a respective web at a same nip, in which case the nip is constituted of two nip rollers, which are typically symmetrical.

[0029] In some embodiments, the apparatus may include, upstream of the nip, a web guide system capable of laterally modifying the position of the web with respect to the lateral ends of the nip (z.e., the Y-position of the web edges relative to the nip), the web guide system including any suitable web guide device which in response to a web edge sensor or any other sensor capable of detecting a position of the web allow the correct positioning of the lateral edges of the web with respect to the nip (hence also with respect to a substrate independently aligned with respect to the same nip). The web guide system may include one or more such web guiding devices being selected from a group comprising an unwinding web guide, a steering web guide, a displacement web guide, and offset-pivot guides, the system further including the sensor, controller and / or actuator adapted to detect and correct (e.g., reduce or eliminate) a deviation from a sought position of the web. For illustration, an actuator of the web guiding system can be configured to displace and / or tilt a roller while the web is moving thereon.

[0030] In some embodiments, the apparatus may include, upstream of the nip, a substrate alignment device configured to modify at least Y-coordinates of the substrate with respect to the nip (hence also with respect to a web and / or pattern thereon independently aligned with respect to the same nip). In some embodiments, the alignment device may laterally shift the substrate by the same distance (to its right or left) as can be measured from its leading edge to its trailing one, the X-coordinates of the corners not being affected by the alignment. In other embodiments, the alignment device may further modify the X-coordinates of at least three of the corners of the substrate. In other words, the alignment device can rotate the substrate relative to the orientation it was originally supplied upon entry on the substrate drive mechanism. These lateral displacements or rotations of the substrate can be achieved inter alia by a substrate alignment device comprising lateral abutments located on opposite sides of the substrate and movable relative to one another in a Y-direction, the lateral abutments being reversibly biased towards one another to grip opposite side edges of the substrate at any desired position with respect to the nip, so as to advance the substrate towards the nip with the desired alignment as controllably set by the abutments.

[0031] In some embodiments, the apparatus may include, upstream of the nip, a speed modifying device adapted to accelerate or decelerate a substrate before its entry into the nip to ensure that the timing of its entry into the nip (z.e., their X-position) should coincide with the entry of the web carrying the pattern to be transferred thereupon.

[0032] The patterns that may be transferred to substrates by use of the apparatus and / or method according to the present teachings can be functional or decorative, the substrates and transferable compositions carried by the flexible web being accordingly selected and adapted to the desired end-use of the transferred patterns.

[0033] Notably, as the patterns are carried by a flexible web, the substrates to which they are to be transferred need not be exclusively rigid and flat, and flexible and / or non-flat (e.g., curved) substrates may also be used and benefit from the present teachings.

[0034] In another aspect, there is provided a method for ensuring that patterns carried by a web of a deformable plastics material conform to a desired length and width following transfer to a substrate at a transfer nip, the method including a) collecting data indicative of the lengths and widths of the patterns on the web prior to transfer, or of the patterns on the substrates after transfer, and b) controlling a temperature of the web and a tension of the web upstream of, or at, the nip in dependence upon the collected data.

[0035] These, and additional benefits and features of the invention, will be better understood with reference to the following detailed description taken in conjunction with the figures and non-limiting examples.

[0036] BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The invention will now be described further, by way of example, with reference to the accompanying drawings, where like reference numerals or characters indicate corresponding or like components. The description, together with the figures, makes apparent to a person having ordinary skill in the art how some embodiments of the disclosure may be practiced. The figures are for the purpose of illustrative discussion and no attempt is made to show structural details of an embodiment in more detail than is necessary for a fundamental understanding of the disclosure. For the sake of clarity and convenience of presentation, some objects depicted in the figures are not necessarily shown to scale.

[0038] In the Figures:

[0039] Figure 1 is similar to Figure 1 of EP 3491902 and is reproduced herein for completeness to show an exemplary apparatus for transferring patterns from a web to substrates;

[0040] Figure 2 is a schematic representation of details of the web feeding apparatus in Figure 1 that have been modified in order to implement the present invention; Figure 3 is a perspective view of part of the web feeding apparatus of Figure 2;

[0041] Figure 4 is a perspective view of a part of a web schematically depicting patterns therein and / or thereon;

[0042] Figure 5 is a perspective view of a part of a web schematically depicting a single pattern and how measurements with respect thereto can be made;

[0043] Figures 6 A to 6C are schematic side views of nips through which the web(s) and substrates may pass to effect transfer; and

[0044] Figure 7 is a flow chart of the steps that may be included to perform a method according to the present invention.

[0045] DETAILED DESCRIPTION

[0046] Overview of the Apparatus

[0047] The exemplary apparatus of Figure 1 is intended to apply patterns to opposite sides of substrates 10, drawn from a substrate supplying device, such as a stack 12, the patterns being of a transferable composition that may contain particles of an electrically conducting material and an adhesive which may later be thermally and / or pressure activated. In such a case, the composition can be sintered by application of energy to render the patterns electrically conductive. Thus, in one example, the substrates 10 may be semiconductor wafers or insulating substrates onto which the apparatus applies the front and back patterns (e.g., electrodes, circuits, antenna, etc.) of the desired end product. However, the composition may not require the application of energy to become conductive, and in some cases electrical conductivity may not be required, the pattern, for example, having other functions or being only ornamental. If the pattern is to be treated to develop its desired functional and / or aesthetic effect, for instance it is to be heated to become electrically conductive, or to be fused or cured to increase adhesion to the substrate, this treatment is typically performed following transfer of the pattern to a suitable substrate and can be performed off-line from the roll-to-roll apparatus exemplified in this figure.

[0048] The two patterns that may be applied to each face of a substrate are usually not the same but may need to be correctly aligned with one another and with the substrate. In the substrate drive mechanism 90, substrates 10 are dispensed one at a time from the stack 12 to an inspection station 60 where the upper surfaces of the substrates can be analyzed optically for defects by a suitable inspection device disposed at the station. In the selection station 62 that follows, substrates found to be defective can be ejected by a suitable selection device. Substrates 10 without defects are advanced onto an alignment device 50 where they can, in one embodiment, also be heated by a heater 52. After being heated, if desired, and correctly positioned and oriented at the alignment station, the substrates 10 are fed into a nip 40 defined, in the present illustration, between two pressure rollers 22a and 22b. A reference numeral assigned to a station (sub-system) in the apparatus can also serve to identify the relevant device performing the function assigned to the station. For illustration, referral 60 can interchangeably be used to refer to the station at which substrates can be inspected, as well as to the inspecting device selected to detect any defect of relevance to the substrates.

[0049] While the inclusion of an inspection station 60 and a selection station 62 to detect and eject defective substrates is recommended, such stations are not essential for the operation of the apparatus, being only preferable from a quality control standpoint. Stations fulfilling similar roles downstream of the nip, and typically following the peeling of the flexible web, when performed, can optionally be further included to detect defective patterns and eliminate substrates bearing such defects. In Figure 1, the downstream inspection of the substrate and / or of the patterns transferred thereto is schematically illustrated by way of sensors 80a and 80b, that can be the same as, or different from, sensors positioned upstream of the nip, such as sensor 70, being for illustration an optical sensor such as cameras 122 and 601, all to be detailed hereinbelow.

[0050] When the apparatus does comprise stations 60 and 62 upstream of the nip, it can be desired to include further an accelerating station 64 allowing a non-defective substrate being drawn after a defective one, which was therefore ejected, to reach the nip in synchronism with the pattern(s) of the web(s). Such accelerating station 64 may therefore prevent an "empty" feeding of the web at the nip, in absence of a substrate. Such an accelerating station is, however, not essential as such empty feeding can be tolerated or mitigated by alternative means, such as adding a substrate pre-selected as flawless from a buffer of such non-defective substrates (e.g., wafers), or by any like solution.

[0051] The station 64 can more generally serve to modify the speed of the substrate being fed to the nip 40, regardless of the presence of an inspecting station 60 or a selection station 62 configured to detect and eliminate defective substrates 10. Accordingly, station 64 can also be referred to as a speed modifying station, the homonym device included therein being capable of accelerating or decelerating the substrate as can be required to ensure that its entry into the nip is synchronous with the pattern(s) on the web(s) with which it is to be aligned. In the present illustration, the patterns of composition that are to be transferred to the substrates are carried by two flexible webs 14a and 14b. The substances to be transferred, also termed transferrable compositions, can be located within recesses below the surface of the web (e.g., grooves) and / or on the surface of the web. The side of the web carrying the pattern of substances can be referred to as the front side of the web, whereas the opposite side of the web can be referred to as its rear side.

[0052] As can clearly be seen from Figure 1, the drive mechanisms of the two webs 14a and 14b can be mirror images of one another. To avoid repetition, reference numerals without a suffix will be used in the present description to refer generically to components of both web drive mechanisms but suffixes "a" and "b" are used in the drawings to distinguish between the upper and lower drive mechanisms.

[0053] Each web 14 is drawn from a motorized supply roll 16 by way of idler rollers 18 and a dancer 20, that can move from left to right, as represented by an arrow 21, so as to draw or release slack of the web. The unwinder 16 may further serve as a web guide, the supply roll being movable in a direction parallel to its longitudinal axis of rotation, so as to adjust the lateral position of the web. In the present view of the apparatus, lateral guidance of the web would be achieved by displacing the supply roll to the front or the rear of the plane of the drawing. Guidance of the lateral edges of the web can additionally, or alternatively be achieved by suitable steering rollers suitably positioned along the path of the web.

[0054] For illustration, roller 18 closer to the nip may serve, if needed, as a steering guide “bending” the web so that it may arrive at a future station (e.g. , at the nip 40) in better alignment with a desired position. Any other displacement guide can be used to achieve lateral guidance of the web, if desired to facilitate meeting additional alignment constraints, all the foregoing web guides being referred to as web guiding systems, each such guiding system including, if needed, its own detection system and controller, as well as any actuator capable of implementing a desired corrective action (such components, if separate, not being shown on the figure).

[0055] The web 14 then passes between the two pressure rollers 22 that define the nip 40 into which substrates are fed. Within the nip, the composition pattern on the web 14 is pressed against a surface of the substrate 10 resulting in the pattern of composition adhering to the substrate. The web then passes, in the present illustration, through a cooling station 23 and between two rollers 26 to a separating device 30. After separation from the substrates 10 by the device 30, the web is rewound on a take-up roll 32. To the extent that the flexible web is separated from the substrates, the web can be disposed of after a single use, in view of the costs of the plastics materials forming it and the methods (e.g., roll-to-roll embossing) that can be used for its manufacturing. A flexible web, if separated, can in some cases be irreversibly deformed, such deformation not affecting the patterns transferred from the separated web.

[0056] To ensure correct registration of the patterns of composition with the substrates, optical sensors 70 are positioned to sense the patterns on the web 14, or markings related thereto, upstream of the idler rollers 18. Any kind of optical sensor can be suitable for the present apparatus, if adapted to the pattern and / or the markings to be detected thereby. Optical sensors can be image sensors, fiber optic sensors, or contrast sensors, or any other like sensor adapted to detect an optical signal.

[0057] Figure 4 schematically presents a perspective view of a web as can be used in an apparatus and method according to the present teachings. In Figure 4, an arrow 400 represents any sensor suitable for measuring the width W and the length L of patterns 410 comprising a transferable composition within or upon the surface of the flexible web 100. Markings 420 and 430 detectable by sensor 400 are provided on the web, the markings being in the present illustration on both sides of the web, this however not being limiting as the markings could alternatively be upstream and / or downstream of each pattern and even positioned within the patterns in some cases. The illustration also shows how specific elements 440 within the patterns may alternatively, or additionally, fulfill a similar detection and measurement function. Downstream of the nip, following peeling of the web, the markings remaining relevant to detections and measurements to be made by a downstream sensor, if present, are typically specific elements within the transferred patterns, unless fiducial markings are made of a transferable material. In this illustration, a single sensor 400 is represented, this being suitable when the field of detection of the sensor is wide enough to perceive all markings of relevance to the intended measurements (e.g., if positioned on opposite sides of the web as shown by markings 420 and 430) and the sensor is disposed with respect to the web so as ideally to detect both its lateral edges. If the field of detection of the sensor is more limited, it may be necessary to use more than one sensor to detect all relevant markings. In the present figure, the thin horizontal lines of the pattern could represent traces known as “fingers” when transferred to a solar cell substrate, whereas the broad transverse lines could represent bus bars. The transferable composition due to form the fingers is typically found in recesses beneath the surface of the web, these grooves having a cross-sectional profile adapted to solar cell fingers (e.g., the crosssection of the grooves being triangular, preferably with a high aspect ratio). In contrast, the transferable composition due to form the bus bars can be found upon the surface of the web.

[0058] While, for simplicity, there has been described herein the transfer of patterns from a web to a substrate involving the control of a web heater and a web tensioner (arranged upstream of the nip of transfer) in dependence only upon data indicative of characteristic dimensions of the patterns (e.g., their lengths and / or widths) measured either on the web prior to transfer or on the substrate after transfer (or both), the lengths and the widths of the patterns need not be the sole dimensions required to be conform to desired values.

[0059] Figure 5 shows a single pattern that will be used to explain how measurements can be derived therefrom, following the acquisition of the relevant data by any suitable sensor, camera or scanner. While the outline of the pattern schematically illustrated in Figure 4, was from top view of a square, in the present illustration the outline of the pattern (indicated by a dotted line) is more of a trapeze to disambiguate some of the following explanations. For simplicity, reference shall be made to a pattern on a web, similar considerations applying to a pattern transferred to a suitable substrate. Thus, while on a web the lateral edges may serve for the positioning (e.g., setting axes from which (x,y) coordinates can be determined) in the plan of the web of measured points (e.g., of the pattern, of its contour, and / or of its associated markings), the lateral edges of the substrate may similarly serve for the positioning of points measured on the surface of the substrate.

[0060] Taking one of the lateral edges of the web as a line of reference (e.g., in the present drawing the lower horizontal border of the web) and a particular point thereon as setting the origin of this axis (z.e., having coordinates (0,0)), the position of any points on the web can be determined by assessing their respective (x,y) coordinates in the X-Y plan in which the pattern resides. The width W and / or length L of the pattern and deviations from desired values, or variations between subsequent measurements of a similar dimension, can be determined by repeatedly measuring at a similar position on each of the patterns the distance between two points indicative of the width or length of the pattern. Four points A-D are marked up on the pattern illustrated in Figure 5, these points being shown on the contour of the pattern at its four corners, but this should not be construed as limiting, the points being alternatively selected from fiducial markings on the web or elements in the pattern. While not shown in this figure, a subsequent pattern may have, at corresponding positions, four characterizing points A’ -D’, with a subsequent pattern characterized by points A”-D”, then A”’-D”’ and so on. The width of the pattern could be assessed by measuring the distance between points A-C or points B-D, and comparing the calculated values with pertinent reference data and / or with similar calculations made between points A’-C’ or points B’-D’, points A”-C” or points B”-D”, or points A”’-C”’ or points B”’-D”’ etc., to monitor a progressive change in width, if any, so as to take corrective actions and / or assess their efficacy. Similarly, the length of the pattern could be assessed by measuring the distance between points A-B or points C-D and comparing the calculated values with pertinent reference data and / or with similar calculations made between points A’-B’ or points C’-D’, points A”-B” or points C”-D”, and so on.

[0061] Alternatively, the width and / or length of the pattern can be calculated as an average of two or more measurements. As the present drawing depicts only four points for characterizing the pattern, an average of two distances would be considered. The width W of the pattern can be calculated by averaging the distance between points A-C (Wl) with the distance between points B-D (W2). The length L of the pattern can be calculated by averaging the distance between points A-B (LI) with the distance between points C-D (L2).

[0062] Having determined, following proper data acquisition, the position of these exemplary four points, more information can be calculated. For instance, the position of the centroid (center of mass) of the pattern can be determined by averaging the location of points A-D in each (x,y) coordinate, this point E being represented by a star in the present drawing.

[0063] Likewise, having determined the coordinates of points characterizing the pattern on the web, further allows assessing the relative positioning of the pattern with respect to the web edges. In some cases, it may not suffice for the pattern to conform to a desired length or width, the pattern being furthermore required to be within a specific area of the web (in other words, out of specific margins). Taking the width of the pattern for illustration, it may not suffice for the distance between points A-C or B-D, or the average of Wl and W2, to meet the reference value set for W, but it may also be required for the distance between each of points A-D and its respective closest projection on the web edge to be greater than the value set for the margins within which the pattern may not reside on the web (or on the substrate following transfer). Likewise, it may not suffice for the distance between points A-B or C-D, or the average of LI and L2, to meet the reference value set for L, but it may also be required for the distance between each of points A-D and its respective closest projection on the substrate edge to be greater than the value set for the margins within which the pattern may not reside on the substrate. A relative displacement between the centroid E of the pattern as derived from the measured points A-D from the ideal position of the centroid of the reference pattern may also be indicative of a skew in the shape of the pattern. Alternatively, the tilt in the orientation of the pattern can be assessed by measuring the angle between an edge of the web and a straight line passing between two points selected for this purpose. For illustration based on the pattern depicted in Figure 5, line A-B could be expected to be parallel to the lateral edge of the web, the angle formed between this virtual line and the edge (e.g., the upper line in the drawing) representing the angle of skew a alpha. To some extent a skew in the pattern can be corrected by subjecting the substrates to a similar skew with the assistance of the alignment device 50 which may include lateral pushers capable of assigning a mild angle to the substrate upon its entry into the nip (e.g., modifying a Y-coordinate of at least one of its corners). In practice, the skew of a pattern (as typically resulting from a manufacturing inaccuracy) may only be corrected if forming an angle with intended orientation not exceeding the ability of the substrate alignment device to slightly rotate the substrate so as to increase the alignment of the edges of the substrate with the intended orientation of the pattern. In other words, and assuming all other parameters to be as desired, the fact that virtual line A-B is not parallel to the lateral edge of the web can be overlooked if the edge of the web was due to be parallel to the lateral edge of the substrate, the substrate being now rotated so as to ensure that its lateral edge be parallel to line A-B.

[0064] The dimensions have so far been discussed in connection with patterns on a deformable web, similar approaches being applicable to the substrates. For rigid substrates, however, the values for their width and length can alternatively be predetermined by the manufacturer, or prior to their loading into the apparatus. That being said, they may also be independently inline assessed by the apparatus with proper sensors adequately located along the substrate drive mechanism. The front and rear edge may serve to determine the length of the substrate, while its lateral edges may serve to determine its width. Points characterizing a substrate can be its four corners, or in the absence of intersecting straight edges, virtual points set at the intersection of straight portions of the substrate edges (said four points being referred to as e.g., Alef, Bet, Guimel, Dalet). The position of the centroid (He) of the substrate can be calculated as explained for a pattern. For proper alignment between a pattern and its substrate, their respective centroids (E and He) may be required to coincide or to be positioned one with respect to the other according to a reference vector. Following transfer, eight points can now be taken into consideration, points A-D characterizing the patterns and points Alef-Dalet characterizing the substrate, allowing to directly assess the actual margins between the contour of the transferred pattern and its substrate. While the figures schematically illustrate an apparatus allowing simultaneous transfer of two patterns onto respective opposite surface of the substrate, the skilled person can readily appreciate how a similar apparatus can be prepared to transfer patterns of composition on a single substrate side. In such a case, nip 40 can, for instance, be formed between a single pressure roller 22 and a backing support 42 for substrate 10. Additionally, the transfer of two patterns onto respective opposite surfaces of a substrate need not be simultaneous, in which case the apparatus may include two separate nips, one for each web and side of the substrate.

[0065] These alternatives are schematically illustrated in Figure 6, in which panel A depicts a single nip 40A formed between one pressure roller 22 and a backing support 42; panel B depicts a single nip 40B formed between two pressure rollers 22a and 22b, which in the present illustration are shown of similar dimensions; panel C depicts two sequential nips 40’ and 40”, each as previously illustrated by nip 40A, when in other cases not shown each separated first and second nip used to transfer to a distinct side of a substrate could alternatively be independently selected from nip types 40A and 40B. In Figures 6A to 6C the surfaces constituting the exemplified nips are shown whilst engaged with one another, the substrates and the webs being omitted for clarity. As readily appreciated by a skilled person, the surfaces forming a nip can also be disengaged when desired, e.g., for servicing, repairing, or cleaning of the apparatus.

[0066] The apparatus may include additional stations that are not shown in the figure, some being optionally off-line stations, to perform activities that can take place at a separate time and / or location, and / or be handled by different entities. For illustration, the apparatus may include a curing station to cure the transferred patterns, a furnace to sinter particles of the transferred compositions and / or to fuse the transferred patterns to their respective substrates, an overcoating station to over-coat the transferred patterns and any like post-transfer treating stations capable of bringing the transferred patterns and their respective substrates closer to an intended ready-to-use end product. Each such station can be referred to as a finishing station whether off-line or in-line. The apparatus may include other in-line stations to facilitate any of the activities already described and further detailed hereinbelow. Some of these stations and related devices may operate on the substrates and / or the web(s) prior to their entry into the nip and be generally referred to as pre-transfer stations (also omitted from the figure for clarity). For illustration, the apparatus may include a pre-coating station which may selectively or continuously apply upstream of the nip a layer of adhesive on the patterns while on the web, on selected regions of the substrates, or on both, the intermediate adhesive layer(s) so formed between the pattern and the substrate facilitating the transfer of the former to the latter at the nip.

[0067] Having given above a general description of an exemplary apparatus in which the present invention can be implemented, individual components and parts of the apparatus will now be described.

[0068] The Substrate Drive Mechanism

[0069] The apparatus illustrated in the drawings is intended for use in the manufacture of solar cells or printed circuit boards where the substrate is typically rigid and has the form of a square semiconductor wafer or a rectangular insulating board. Before describing the drive mechanism in detail, it should be made clear that its design will depend in practice on the nature of the substrate, which in turn may depend on the type of patterns to be transferred thereto (e.g., functional or decorative). If, in alternative embodiments, the substrate is itself flexible, then the drive mechanism of the substrate may resemble that of the web. If the substrate is a 3D article that is only to have a (e.g., conductive) pattern applied to one side, then the substrate drive mechanism 90 may be a conveyor passing beneath a single pressure roller 22. Such adaptations and modifications can readily be implemented by a skilled person and need not be further detailed herein.

[0070] In the case of the embodiment illustrated in Figure 1, the substrate drive mechanism 90 includes a cassette within which a stack 12 of individual substrates 10 are stored. By means of a conveyor belt (not shown in the figure), the substrates 10 can be dispensed one at a time from the stack 12 to the inspection station 60 (e.g., for optical detection of defects) where they can be viewed from above by a camera 601. The image from the camera can be analyzed by a computer programmed to detect defects and flaws, such as cracks. The selection station 62 that follows the inspection station 60 may include, by way of example, a solenoid operated deflector that is under the control of the image analysis computer of the preceding station and displaces faulty substrates off the conveyor into a waste receptacle. Only substrates without defects are then allowed to pass to the next station(s), where they can be heated, if desired, and correctly aligned with respect to the nip and the pattern(s) to be transferred thereto. Correct positioning of the substrates with respect to the nip can be achieved by way of suitable abutments. Correct registration with respect to incoming patterns carried by a web can be achieved by way of acceleration or deceleration of the feeding of the substrate to the nip, in accordance with the distance of the pattern from the nip and of the speed of the web. In some embodiments, the substrate drive mechanism 90 is configured and adapted to feed substrates to a nip 40 at a linear speed of at least 0.1 meter / second (m / s), at least 0.5 m / s, or at least 0.7 m / s. Typically, a linear speed of a substrate at a nip does not exceed 2.0 m / s, and is generally in a range of 0.2 m / s to 1.5 m / s, of 0.4 m / s to 1.0 m / s and of 0.5 m / s to 0.8 m / s.

[0071] Heating and Alignment Station

[0072] As its name implies, this station serves two separate functions. First, it serves to heat, when preferred, the substrate 10 to a temperature that will activate the adhesive in the composition carried by the web 14 when the two are brought into contact at the nip. The appropriate temperature will depend on the nature of the composition and the adhesive and is discussed in more detail in EP 3491900.

[0073] The heating station (represented by the dotted box 52) may take different forms, depending on the temperature to be reached, and can be by conduction (the substrate coming into contact with a hot plate, that is heated by a circulating fluid, a resistive heating element or PTC resistors), by convection (blowing a heated gas onto the substrate) or by radiation (infrared or microwave, depending on the nature of the substrate). When heating is performed by conduction, it may be desired to further include elements capable of maintaining the substrate in intimate contact with the hot plate (e.g., rollers forming a nip with the plate) to accelerate substrate heating to the desired temperature.

[0074] While heating can be performed upstream of the nip, to heat separately at least one of the web and substrate surfaces due to be urged one into contact with the other, it can alternatively, and / or additionally, be performed at the nip. For instance, the pressure roller 22 may, in such embodiments, additionally serve as a heating roller.

[0075] The web 14 is made of a flexible material into which grooves can be formed by any of a variety of possible processes (e.g., by embossing or casting). The grooves, of which the geometry is complementary to that of the desired pattern e.g., of conductors, can be filled with a composition that contains particles of an electrically conductive material, for example of silver, and a thermally and / or pressure activatable adhesive. As mentioned, for certain types of relatively flat conductive patterns, such as back electrodes of solar cells and ground planes of PCBs' ground planes, the composition can alternatively be positioned on the surface of the web. In the present context, it suffices to know that the web carries patterns of the composition matching at least a part of the desired patterns (e.g., of conductors) to be applied to the substrate, but the interested reader will find in EP 3491900 more detail on the type of material from which the web can be made, the manner in which the grooves can be made, and the chemical structure of the components of the composition. It should be mentioned that the composition need not itself be conductive but could become conductive once sintered, if conductive patterns are sought. Moreover, while the present description mainly refers to the transfer of a pattern intended to become conductive, the invention should not be construed as limited to such patterns. The present invention may be beneficial to the transfer of any kind of pattern (e.g., having a function other than electric conductivity or being decorative) for which maintaining the size of the transferred pattern within strict dimensions, or tolerated deviations therefrom, is important.

[0076] For the present purpose, it can be briefly noted that the web is sufficiently non-elastic to maintain the contour of the grooves (and patterns) and the shape of the compositions to be transferred therefrom. On the other hand, the web has enough elasticity (e.g., stretchability) to facilitate registration of patterns carried thereon with the substrate by way of dancers and tensioning. Thus, the plastics materials of which the deformable web (or a layer thereof, typically the one due to contact the substrate) can be made include any polymer capable of shape changing as a result of the operating conditions of the apparatuses manufacturing the webs (e.g., embossing them) or using the webs for transfer. Moreover, the web of deformable plastics can be irreversibly deformed during its separation from the substrates, so that it is suitable for a single use following which it can be discarded. Materials suitable for such webs (or outermost deformable layer) can be thermoplastic polymers comprising cyclic olefin copolymer (COC), polypropylene (PP), polyethylene (PE), thermoplastic polyurethane (TPU), and copolymers thereof, to name but a few.

[0077] Dancers may also serve as buffers until the web reaches a constant speed. As the various motorized cylinders that would be contacting the web on its path have different diameters, there can be some inertia between them until all can provide a same linear speed. The web is preferably flexible enough to conform to the surface of the substrate, to permit a sufficiently intimate contact for transfer of the composition lines. This capacity is associated with the presence of a thermoplastic polymer at least in a layer forming the first surface / front side of the web. It is believed that upon heating as aforesaid, the thermoplastic layer of the web first surface can soften sufficiently to match substantially the topography of the substrate surface. For illustration, assuming the substrate has a random or patterned textured surface, e.g., with pyramid like protrusions as may be found in silicon substrates for solar cells, the conformability of the web, in particular when heated, allows the thermoplastic surface to fill substantially the relatively shallow spacings between neighboring relatively protruding textures. It is stressed that thermosetting polymers, such as used for the preparation of dimension-wise resilient molds (such as used in intaglio plates) are not capable of such topographic conformity under normal operating conditions.

[0078] Other desirable properties can be readily understood, so as to render the web compatible with the process implemented by the apparatus (e.g., stress resistant, heat resistant, heat conductive or dissipative, and the like) and with the compositions used therein (e.g., chemically resistant, chemically inert, etc. , while being responsive to the changes in temperature and tensioning allowing for the modulation of the patterns lengths and widths according to the present teachings.

[0079] The Pressure Rollers

[0080] The purpose of the pressure roller(s) 22 is to press the web 14 against the substrate 10. A force is applied to the pressure roller 22 to apply a compressive force at the nip 40, the magnitude of the force depending on the nature of the web, the compositions carried therein and / or thereon and the substrate, as well as on the geometry of the pattern (e.g., the depth and / or cross-sectional profile of a groove, complexity of the patterns, etc.). The speed at which the web is fed to the nip (z.e., the period of time it would be subjected to pressure) and the desired quality of transfer may also affect the magnitude of the applied force. The pressure roller may be made of any suitable material, for instance of a rubber or of steel but coated with a thin layer of a compliant material to ensure good contact over the entire surface area of the web. Therefore, while the nip can be ideally considered as the line of contact formed between the web and a face of the substrate, in practice the presence of compressible material on the side of the nip coming into contact with the rear side of the web causes the nip to form an area of contact elongated in a direction parallel to the width of the web.

[0081] As mentioned, in some embodiments, when heating is not exclusively performed on the substrate, nor on the web upstream of the nip, the pressure roller 22 can additionally serve as a heating cylinder. The pressure roller can furthermore be motorized to draw the web from the supply roll 16. When the nip is formed between two pressure rollers, as illustrated in the figure, it suffices for only one of the pressure rollers to be motorized, when desired.

[0082] It is important to ensure that when the patterns on the web 14, regardless of whether they are beneath and / or above the surface of the web, arrive at the nip 40, they be synchronized with the arrival of the substrates. The patterns of composition are spaced on the web so that blank web may pass through the nip 40 while a fresh substrate is being oriented for correct presentation to the nip, the alignment being optionally performed whilst the substrate is being heated. A problem arises because the web is driven continuously whereas the presentation of substrates to the nip 40 is intermittent, hence the arrival time of the patterns at the nip may not coincide with the presence of a substrate in the nip.

[0083] To avoid this problem, web is drawn from the supply roll 16, be it by rotation of the supply roll 16 or the take-up roll 32. A sensor 70 is provided to detect the arrival of patterns at a certain position as the web comes away from the supply roll 16. If the expected arrival time of the pattern at the nip 40 does not coincide with the next arrival of a substrate 10 at the nip 40, then the movement of the dancer 20 can vary the length of the path of the web from the supply roll 16 to the nip 40, which has the effect of increasing or decreasing the time taken for the sensed pattern to reach the nip 40. Thus, controlling of the dancer 20 in dependence upon the time that a pattern is sensed by sensor 70 and the time that a substrate 10 is fed to the nip 40, it is possible to ensure correct registration between the patterns and the substrates. If patterns on opposite surfaces of a substrate are both correctly in register with the substrate, then they will also be in correct register with one another.

[0084] While any suitable alignment device 50 may be used in connection with the present invention, the Applicant has conceived various methods for timely feeding a substrate to a nip, while ensuring its proper alignment with its respective pattern. In addition to the devices disclosed in EP 3491902, the interested reader will find in EP 4049308 and EP 4320059 alternative methods and devices for their implementation, all such devices being capable of serving as alignment device 50. In some cases, it can be advantageous to use an alignment device capable of tilting the substrate to match a skew in the orientation of the patterns on the web, if such a situation is observed prior to or following transfer of the patterns.

[0085] The Cooling Station

[0086] The cooling of the web 14 after it has passed through the nip 40 is carried out in the illustrated embodiment by means of conduction. An endless cooling belt 24 passes over first and second rollers 26 and is maintained in tension by an idler roller 28. In this way, the cooling belt 24 is maintained in thermal contact with the rear side of the web over the entire run extending from the pressure roller 22 to the second roller 26.

[0087] The cooling belt 24 is exposed to ambient air over the remainder of its length and may not need additional cooling. Should there be a need to cool the belt 24, a blower may be provided for blowing air onto it, the air being preferably, but not necessarily, cooled.

[0088] As an alternative, it would be possible to dispense with the cooling belt 24 and to cool the web downstream of the nip by directly blowing air onto its rear side. The air may, if necessary, be cooled, such as by means of a refrigeration circuit, to a temperature not exceeding 20°C. As a further alternative, the cooling belt can be replaced by any heatsink suitable to lower the temperature to a desired range of temperatures.

[0089] While passing through the cooling station 23, the web 14 remains attached to the substrates 10 but as the web cools, the adhesion of the composition to the web decreases and / or conversely the adhesion of the composition to the substrate increases, such changes in relative adhesivity to respective source and target surface assisting in the subsequent separation of the web from the substrates, as and when desired. Thus, the temperatures to be reached or maintained by the cooling station may depend on the web, on the substrate and on a future action they might be jointly subjected to. When the cooling station is a heatsink, it can advantageously be controlled so that the temperature of the web and the substrate upon exit from the cooling station is adapted to the function to be performed at a downstream station.

[0090] As the active cooling of the web 14 and / or its underlying substrate 10 is intended to facilitate a proper separation of the web from the substrate, so that that pattern of transferable composition remains adequately attached thereto, the cooling can be superfluous if no separation of the web is sought, or at least not imminently.

[0091] The Separation Device

[0092] The separation device 30 illustrated in the exemplary embodiment of the depicted apparatus comprises a metal plate that is bent or manufactured to define an acute angle, such as can be found in a blade. The web on its return path to the take-up roller 32 is bent over the sharp edge defined by the outer sides of the separation device. This action peels the web 14 away from the substrate 10 leaving the composition adhering to the substrate 10. A skilled person will readily appreciate that alternative separation devices, e.g., upon which the web may revolve towards the take-up roller, can satisfactorily achieve similar peeling of the web, when such separation is desired, a rod or a rotating cylinder being but examples of such alternative devices.

[0093] In some embodiments, it may be desired to maintain the web 14 attached to the substrates 10, either as a temporary protection to the patterns, until separation is made at a later time (optionally at different facilities and / or by different entities), or as a permanent casing to the patterns. In such a case, the web 14 need not be rewound by a take-up roll 32 but only drawn from the supply roll 16 by any suitable device adapted to this purpose. Moreover, when separation of the web(s) from the substrates is delayed or omitted, it may not be necessary to cool the web 14 downstream of the nip 40 or to cool it to a temperature selected to facilitate separation. Furthermore, in such a case, and in particular when the substrates are fed to the nip as separate individual units, the apparatus may include a cutting device to slit the web remaining on the substrates in the unbound margin between any desired number of adjacent substrates. The cutting device (not shown in the figure) may disconnect each single substrate from the following one or may disconnect sets of two or more substrates from a following set of substrates.

[0094] An embodiment of the present invention is shown partially in Figures 2 and 3. For clarity, many components already discussed with reference to Figure 1, such as the substrate supplying device (e.g., 12), the substrate drive mechanism (e.g., 90, the conveyor not being shown) and the alignment station (e.g., 50), as well as the optional substrate inspection station (e.g., 60), selection station (e.g., 62), speed modifying station (e.g., 64) and heating station (e.g., 52), found upstream of the nip, are omitted, as are any other pre-transfer stations that may be desired for a particular apparatus (or method). Likewise, for post-transfer stations that may be found downstream of the nip (40) or even downstream of a separating station (e.g., 30), if present.

[0095] Figures 2 and 3 show schematically only the part of the apparatus shown in Figure 1 that has been modified in order to implement the present invention. The web 100 in Figures 2 and 3 drawn from a motorized supply roll (not shown but equivalent to the roll 16 in Figure 1, which as mentioned can also be a web guiding unwinder) in a direction shown in the region of the nip by arrow 130 passes first over a dancer 102 disposed between two guide rollers 104 and 106. The web 100 next passes over a further guide roller 108, through a tensioning nip formed between a motorized tensioning roller 110 and a rubber roller 112 which is forced against the web at a constant pressure to ensure there would be no slippage between tensioning roller 110 and the web 100. The web is concomitantly and / or thereafter heated by a web heater (e.g., by passing around a heated roller 114) before reaching the nip roller 116 at which the patterns are transferred from the web 100 to substrates. The nip roller 116 (equivalent to pressure roller 22 in Figure 1), or at least one of them (e.g., the upper one) when the nip is formed between two nip rollers as illustrated in the figures (e.g., as nip 40), can be motorized to drive the web 100.

[0096] The dancer 102 is equivalent to the dancer 20 in Figure 1 and its role is to serve as buffer during initial acceleration, and / or final deceleration, of the system when the linear speeds of the different rollers have yet to match one another. The dancer is also associated with a camera 118 that is used to ensure correct registration of the patterns with the substrate by accelerating or decelerating feeding of the substrate. The position of the substrates with respect to the nip can be ascertained upstream of the nip by way of sensors (e.g., optical sensors) which can monitor either the edges of the substrates, fiducial marks on the substrates, or both. Such sensors may be part of the substrate alignment device (depicted as station 50 in Figure 1).

[0097] A control system 120 is provided to compensate for errors in the dimensions of patterns transferred to the substrates. As represented by dotted lines in Figure 2, the control system is electrically connected to receive data signals from cameras 122 and from a shaft encoder associated with the nip roller 116, and to send control signals to set the speeds and / or torques of the motorized tensioning roller 110 and the temperature of the heating roller 114 or alternatively, and additionally, of any other heating device disposed along the path followed by the web upstream of the nip or in the nip. For illustration, a segment of web 100 between guide roller 106 and nip roller 116, or between tensioning roller 112 and heated roller 114, can be heated by convection or by radiation (e.g., using an infra-red heater).

[0098] As shown in Figure 2 and best seen in Figure 3, two cameras 122 can be positioned to view fiducials on opposite sides of the web 100 as it passes over the nip roller 116. Additionally, or alternatively, cameras may be positioned to view fiducials on patterns after they have been transferred to substrates. From the detection of the position of the fiducials, deviations in the width separation of the fiducials from a desired dimension can be determined by the control system 120. Furthermore, from measurement by the shaft encoder associated with the nip roller 116 of the movement of the web 100 between sensing of consecutive fiducials, the control system 120 can ascertain deviations in the lengths of the patterns from a desired dimension.

[0099] Variations in the widths of the transferred patterns can be managed by the control system 120 by varying the temperature provided by the heating devices upstream of the nip (e.g., of the heating roller 114), which will in turn vary the temperature of the web 100 and the degree that it (and patterns thereon) will spread when compressed against the substrate by the nip roller 116

[0100] Variations in length of the transferred patterns can be brought about by the control system 120 by varying the tension in the web 100 immediately upstream of the nip roller 116. Tension control can be achieved by varying the relative speed and / or torque between the motors driving the nip roller 116 (or one of them if the nip is formed of a pair) and the tensioning roller 110. By “immediately” it is meant that while not necessarily being instantaneous or at an exact preceding spot, the change being effected by the control system prior to entry of the web into the nip is performed at a time and / or spot sufficiently close to this event for the controlled effect to last to a degree sufficient for the modification(s) intended at the nip.

[0101] The degree of tensioning that needs to be applied to the web will depend inter alia on the specific web, the dimensions of the patterns to be transferred and their divergence from nominal and tolerated values, and the temperature of the web (e.g., between 20°C and 80°C).

[0102] Tolerable deviations in dimensions and / or positions of patterns may depend on the pattern to be transferred and / or on the parameter under consideration. For illustration, the deviation tolerated from ideal dimensions (e.g., length and / or width of the pattern, of transfer regions and / or of no-transfer regions) or from ideal positions (e.g., of points characterizing the pattern, the substrate or their respective centroids) can be in absolute terms of up to 100 pm, up to 50 pm, up to 25 pm, up to 10 pm, up to 5 pm, or up to 1 pm. Alternatively, or additionally, such deviations can be in relative terms from the values sought for the data of reference, such as being within 1% of the ideal dimension and / or position, or within 0.5%, or within 0.25%, or within 0.1%, or within 0.05% of the pertinent nominal value(s) (e.g., be it a distance between two points or coordinates of a point).

[0103] Regardless of the margins of tolerance encompassing ideal values, the present apparatus can correct deviations being up to twice the upper value of acceptable variation in any dimension, the apparatus being in some embodiments capable of correcting an up to 5-fold deviation, up to 10-fold deviation or up to 20-fold deviation. If, for illustration, a pattern may have a width within 10 pm of ideal width value and a length within 50 pm of ideal length value to remain satisfactory upon its intended substrate, then the apparatus is adapted to modify the widths and / or the lengths of the patterns carried by the web to be within 200 pm and / or 1000 pm of respective ideal values. Considering the angle of skew of a pattern, in some cases the present apparatus may allow to correct a mis-orientation of the patterns with respect to the web having an alpha angle of up to 2°. In some embodiments, the apparatus can be used to properly align with their respective substrates, patterns having an a angle of 1.5° or less, 1° or less, or 0.5° or less. Ideally, there is substantially no skew (« < 0.03°) between the orientation of the patterns as observed on the web (or on the substrates following transfer) and the intended “reference” orientation of these patterns on these respective supports.

[0104] The apparatus is shown for symmetry as having two controllers 120 but it will be appreciated that in practice a single controller could be used for both webs based on data received from different cameras for each web, in the event that the apparatus is designed to transfer patterns from two different webs to opposite sides of a same substrate (e.g., at a same nip or at two distinct nips).

[0105] In some embodiments, the data read by the cameras 122 may be encoded data, written on the web at the time of its manufacture, indicative of either the lengths and widths of the patterns as measured at the time of their manufacture, or optimum setting for the amount of heat and tension to be applied to the web to achieve a desired consistent size of the patterns after transfer to the substrates. Such data need only be entered on one lateral side of the web and a single camera would suffice for each web.

[0106] While heat is the predominant parameter for determining widening of the patterns during the transfer and tension is the predominant parameter for determining the lengthening of the e.g., conductive) patterns, these two adjustments are not independent of one another as heating may lengthen the patterns and tension may narrow them. The controller must therefore take both the measured length and width measurements into consideration when setting the degree of heating and the web tension.

[0107] The controller may contain a look-up table that will indicate the optimum heating and tensioning based on the measured widths and lengths of the patterns on the web or may use a recursive algorithm to arrive at the optimum settings.

[0108] It should be understood that the feedback loop that varies the heating and tensioning of the web during the process cannot respond sufficiently quickly to correct variations in dimensions from one pattern to the next. However, from readings taken at the commencement of a web, the controller can arrive at heating and tensioning settings for the remainder of the web and from reading taken during transfer of patterns from a web, the settings can be modified to compensate for slow long terms drifts in the measured lengths and widths of the patterns.

[0109] Overview of the Method

[0110] The method previously explained with respect to an apparatus adapted to implement it, shall now be described with respect to Figure 7. It must be stressed that while the prospective steps have been assigned numerical values, they need not be performed according to their sequential numbering.

[0111] Typically, in a first step marked as SOI in the figure, at least one web bearing the patterns and the substrates to which they are to be transferred are driven towards the nip, the substrates being fed one at a time. Preferably, the web and the substrates are pre-aligned before their entry into the nip, the positioning of the web lateral edges with respect to the nip being addressed by a web guiding system and the positioning of the substrate by a substrate alignment device.

[0112] As mentioned in the description of the apparatus, this step may include the inspection of the substrates, their sei ection / rej ection, and / or their heating. Furthermore, to the extent that at a later stage a deviation is detected in the alignment of the patterns and their substrates, the feeding of the substrate can be modified as part of the actions taken to correct such a mismatch gradually. For illustration, the substrates can be accelerated or decelerated as needed until the speed of the web and the substrates can be matched again; and / or the substrates can be tilted during their alignment so as to match a skew in the orientation of the patterns on the web.

[0113] In step S02, the dimensions (lengths and / or widths) of the patterns are determined on the web before it enters the nip. This step includes data acquisition, which can be made by any suitable sensor adapted to detect elements of the pattern or fiducial markings present on the web in areas other than the patterns, followed by the analysis of the acquired data, for actions to be derived in response thereto.

[0114] The sensors and the markings must be compatible with one another, and typically optical sensors are used for optically detectable markings. This step can alternatively serve to read data encoded in the web during its manufacturing, such encoded data setting the recommended tension and / or temperature for each particular web, or may furthermore combine both approaches of initially setting values recommended at the manufacturing stage with values derived from measurements actually performed during feeding of the web to the nip. This step can be partly or entirely omitted and replaced by step S05 to be later detailed, in which similar data acquisition and analysis, simply referred to as the measurements, can be made once the patterns are transferred on the substrates.

[0115] Assuming that the measurements relating to the patterns were performed at step S02 on the web, the measured lengths and / or widths are compared to the values ideally sought (the reference data), see step S06, and if deviating therefrom, the tension and / or temperature of the web prior to its entry into the nip can be adjusted accordingly (see step S03). Such adjustments can be made even if the divergence between measured and sought values is within tolerance (e.g., so as to avoid or limit future departure therefrom). As previously mentioned with respect to the explanations provided in relation with Figure 5, though for simplicity the steps are referring to the measurements of the lengths and / or widths (or comparison to reference values for the same), in some cases it may be desired to assess additional characteristics of the patterns, such as the position of its centroid (point E in Figure 5), the relative positioning of the pattern with respect to the edges of the web (in particular when margins are to be avoided for a transfer to a proper area of the substrate), and the skew of the pattern (if any) from a reference orientation of the reference pattern. Moreover, while step S02 refers to the measurement of dimensions characterizing the patterns on a first web (e.g., lengths, widths, centroids position, pattern skew, position relative to web edges or lateral margins etc.), the following step S03 of setting the web tension and / or temperature in response to said measurements, may additionally take into account measurements made with respect to the substrate to which the pattern would transfer, as well as similar measurements made with respect to a second pattern carried by a second web and due to transfer to the other side of the substrate, if relevant. In the case of two webs, as the substrate can only be aligned once with respect to both, it could advantageously be set to be at mid-distance between the two patterns (if each relatively deviating from intended position), so that the absolute deviation of each pattern with respect to the substrate could be halved.

[0116] Setting of the web tension and / or temperature (as associated with S03) can initially be done empirically or based on input from the manufacturer of the web, this primary feedforward control being however often insufficient to take into account ongoing changes in patterns dimensions and gradual draft in transfer accuracy. The following corrections of such initial settings is done as a feedback mechanism based on measurements of the patterns while on the web (S02) or following their transfer from the web to their respective substrates at the nip (S04), the measurements (data acquisition and analysis) of e.g., the actual lengths and / or widths of the patterns being now performed while they have transferred to the substrates (S05). If desired the measurements of the patterns can be done both before (S02) and after (S05) transfer. As explained with respect to S02, the dimensions characterizing the patterns on a first side of the substrates (e.g., lengths, widths, centroids position, pattern skew, position relative to substrate edges or lateral margins etc.), can be compared not only to the respective reference values, but also to similar values measured with respect to the substrate to which the pattern would transfer and / or with the patterns on the second side of the substrates.

[0117] If the control of the web tension and / or temperature is in response to measurements made on the substrate S05 following transfer, the measured e.g., lengths and / or widths are compared to the reference data in step S06, and if deviating therefrom, the tension and / or temperature of the web prior to its entry into the nip can be adjusted accordingly (see step S03).

[0118] If measurements of dimensions characterizing the patterns on the web (performed at S02) and / or on the substrate (performed at S05) when compared to measurements indicative of the position of the substrate suggest that while the pattern would conform desired values (e.g, inter alia thanks to step S03), the substrate might need be advanced or delayed relatively to the pattern, then a corrective action in a subsequent step SOI might additionally include decelerating or accelerating the substrates upstream of the nip to ensure correct alignment of the patterns with the substrates.

[0119] As separately explained, if the deviation from a desired output relates to the relative Y- position and / or orientation of the pattern with respect to the web or a substrate (if no corrective action is taken), step SOI (or a one following the discovery of the problem) might alternatively (or additionally) include laterally displacing and / or tilting the substrate so it enters the nip with a desired Y-position or skew angle substantially matching the corresponding position or angle of skew of the orientation of the pattern on the web.

[0120] In summary, the preventive or corrective actions that can be performed in the present method prior to entry into the nip may include, in addition to the basic steps of A] feeding the web and the substrates to the nip (SOI) and B] controlling the tension and / or temperature of the web (S03), one or more of: a) Adjusting the lateral position of the web(s) (e.g., by operation of a web guiding system); b) Adjusting the lateral position of the substrates (e.g., by operation of a substrate aligning system evenly modifying the Y-positions of the substrates along their lengths); c) Adjusting the position of the leading edge of the substrates (e.g., by modifying their speed); and d) Adjusting the orientation of the substrates (e.g., by operation of a substrate aligning system differentially modifying the Y-positions of the substrates along their lengths).

[0121] Each aforesaid potential (e.g., responsive) action may not necessarily eliminate totally a deleterious deviation from a desired parameter, provided that it is sufficient to reduce such deviation so as to be within tolerable variations from the sought value(s). In some cases, it can be desired to combine two or more corrective measures to be within the range of tolerated deviations, in which case not all measures being combined need be individually effective, as long as their joint action is satisfactory to reduce the deviation.

[0122] Exemplary Applicability

[0123] The transfer process enabled by the above-detailed apparatus and related method is suitable for rigid or flexible, flat or curved substrates, the exact nature of which being selected according to the intended manufactured article. Substrates for the transfer of functional patterns, such as employed in the manufacturing of electronic components, can be any substrate adapted for the preparation of articles such as printed circuit boards (PCBs), integrated circuits (IC), radio frequency identification (RFID) tags, Liquid Crystal Displays (LCDs), wave guides, thin film devices and photovoltaic (solar) cells, to name but a few. Such substrates are known to the persons skilled in the relevant field and need not be detailed herein. Substrates for the transfer of ornamental patterns are even less restricted, provided suiting the apparatus and method according to the present teachings.

[0124] Considering for illustration substrates suitable for the manufacturing of solar cells, they may include single-junction and multi -junctions, rigid wafers and flexible thin-films, typically made of semiconductor materials including organic semiconductors and inorganic ones such silicon (crystalline or amorphous), gallium arsenide (e.g., in single-junction GaAs cells), cadmium telluride (CdTe), copper indium selenide (CuInSe), perovskite materials (having a crystal structure according to formula ABX3, such as calcium titanium oxide (CaTiCf)) and copper indium gallium selenide (CIGS), to name but a few, some materials being additionally doped or passivated in particular photovoltaic cells. The thickness of such substrates can be as low as a few nanometers (nm) to tens of micrometers for thin films, at which their thickness overlaps with thin wafers (e.g., having a thickness of about 25 pm), more common wafers not exceeding 1 millimeter, and being preferably thinner than 500 pm or 250 pm. As readily appreciated, some of the aforesaid substrates, if rigid, are relatively fragile and brittle, challenging any apparatus and method for ensuring proper transfer of a pattern without breakage of the substrate.

[0125] In addition to the features of the above disclosure that are claimed in the appended claims, features believed to be inventive in their own right are set out in the clauses below, to provide fair basis for eventual filing of one or more divisional patent applications.

[0126] Clauses

[0127] 1. A method of ensuring that patterns carried by a web of a deformable plastics material conform to a desired length and / or width following transfer of the patterns to a substrate at a transfer nip that comprises a rotatable nip roller and at which the web and the substrate are pressed against one another, the method including a) collecting data indicative of at least one of the lengths and widths of the patterns

[0128] (i) on the web prior to transfer of the patterns to the substrates, and / or (ii) on the substrate following transfer of the patterns to the substrates, and b) controlling at least one of a temperature and a tension of the web upstream of, or at, the nip in dependence upon the collected data.

[0129] 2. The method of clause 1, wherein the transfer nip is defined between the rotatable nip roller and a stationary backing support.

[0130] 3. The method of clause 1, wherein the transfer nip is defined between the nip roller and a counter-rotatable second nip roller.

[0131] 4. The method of any one of clause 1 to clause 3, wherein the temperature and / or the tension of the web are controlled by a control unit serving to operate at least one of a web heater and a web tensioner in response to the data collected with respect to the lengths and widths of the patterns.

[0132] 5. The method of any one of clause 1 to clause 4, wherein the data indicative of the lengths and / or the widths of the patterns is collected by at least one sensor disposed along the web upstream and / or downstream of the nip.

[0133] 6. The method of clause 5, wherein one of the at least one sensor is an optical sensor.

[0134] 7. The method of clause 5 or clause 6, wherein data indicative of the lengths and / or widths of the patterns is derived from detection by the or each sensor of elements of the patterns.

[0135] 8. The method of any one of clause 5 to clause 7, wherein data indicative of the lengths and / or widths of the patterns is derived from detection by the or each sensor of fiducials distinct from the patterns.

[0136] 9. The method of any one of clause 5 to clause 8, which method further comprises providing a shaft encoder associated with the nip roller, the encoder being capable of measuring the movement of the web and the substrates through the nip, the length of web passing through the nip between detection of consecutive specific markings by the optical sensors being indicative of the length of the patterns on the web or the substrates.

[0137] 10. The method of any one of clause 1 to clause 9, wherein the lengths and / or widths of the patterns are measured during manufacture of the web and data are placed on the web to indicate the optimum temperature and tension of the web during transfer of the patterns to the substrates, and wherein at least one of a temperature and a tension of the web upstream of, or at, the nip is controlled during transfer of the patterns to the substrates based on the data read from the web. 11. The method of any one of clause 1 to clause 10, wherein the tension in the web is controlled by varying the speed or torque of motors driving two spaced rollers serving to advance the web.

[0138] 12. The method of any one of clause 1 to clause 11, wherein the substrates are fed to the nip by a substrate supplying device and a drive mechanism for transporting the substrates to the nip where the substrates are aligned prior to entry of the substrates into the nip, the method optionally including, prior to said entry one or more of: a) inspecting the substrates for defects; b) selecting the substrates substantially free of defects; c) modifying the speed of the substrates (e.g., by acceleration in case a defective one is thrown off at a previous step of selection); and d) heating the substrates.

[0139] 13. The method of clause 12, wherein the alignment of the substrates includes setting at least the Y-position of the substrates with respect to the nip and / or rotating the substrate, said alignment being optionally performed by lateral abutments.

[0140] 14. The method of clause 12 or clause 13, wherein the substrates are accelerated or decelerated prior to entry into the nip so as to be aligned with patterns upon entry into the nip.

[0141] 15. The method of any one of clause 1 to clause 14, further comprising laterally guiding the web prior to entry into the nip.

[0142] 16. The method of any one of clause 1 to clause 15, further comprising, after transfer of the patterns to the substrates, cooling the web and / or the substrates whilst attached one to the other downstream of the nip; the method optionally including slitting the web between one or more substrates.

[0143] 17. The method of any one of clause 1 to clause 16, further comprising peeling the web away from the substrates after transfer of the patterns to the substrates.

[0144] 18. The method of any one of clause 1 to clause 17, wherein the patterns include at least one transferable composition carried within recesses in and / or on a first surface of the web; the web being made of one or more layers of plastics material and having at least the first surface made of a conformable thermoplastic polymer.

[0145] 19. The method of clause 18, wherein the or each transferable composition contains particles of one or more materials and an adhesive being activatable by heat and / or by pressure prior to or during passage through the nip. 20. The method of clause 19, wherein at least one transferable composition contains particles made of an electrically conductive material.

[0146] 21. The method of clause 20, the method further comprising rendering the pattern, or a part thereof containing particles made of an electrically conductive material, electrically conductive, this step including sintering and / or fusing the pattern transferred to the substrate.

[0147] 22. An article comprising a pattern applied on a substrate, wherein the pattern conforms to a desired length and / or width and deviates therefrom by no more than 100 pm and / or 1% of the respectively desired length and / or width, the article being manufactured using an apparatus and / or a method as set forth in the clauses and claims and substantially as detailed in the present teachings.

[0148] 23. The article of clause 22, wherein the pattern further conforms to a desired position on the substrate and deviates therefrom by no more than 100 pm and / or 1% of the desired respective coordinates of points indicative of the pattern.

[0149] 24. The article of clause 22 or clause 23, wherein the pattern further conforms to a desired orientation with respect to the substrate and deviates therefrom by no more than 3 degrees.

[0150] It is appreciated that certain features of the disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the disclosure. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

[0151] Although the present disclosure has been described with respect to various specific embodiments presented thereof for the sake of illustration only, such specifically disclosed embodiments should not be considered limiting. Many other alternatives, modifications and variations of such embodiments will occur to those skilled in the art based upon Applicant’s disclosure herein. Accordingly, it is intended to embrace all such alternatives, modifications and variations and to be bound only by the scope of the clauses and the claims of the present disclosure and any change which comes within their meaning and range of equivalency.

[0152] In the description and claims of the present disclosure, each of the verbs “comprise”, “include” and “have”, and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of features, members, steps, components, elements or parts of the subject or subjects of the verb. Nevertheless, it is contemplated that the methods of the present teachings also consist essentially of, or consist of, the recited process steps, and that the apparatus of the present teachings also consist essentially of, or consist of, the recited devices.

[0153] As used herein, the singular form “a”, “an” and “the” include plural references and mean “at least one” or “one or more” unless the context clearly dictates otherwise. At least one of A and B is intended to mean either A or B, and may mean, in some embodiments, A and B.

[0154] Positional or motional terms such as “upper”, “lower”, “right”, “left”, “bottom”, “below”, “lowered”, “low”, “top”, “above”, “elevated”, “high”, “vertical”, “horizontal”, “backward”, “forward”, “upstream” and “downstream”, as well as grammatical variations thereof, may be used herein for exemplary purposes only, to illustrate the relative positioning, placement or displacement of certain components, to indicate a first and a second component in present illustrations or to do both. Such terms do not necessarily indicate that, for example, a “bottom” component is below a “top” component, as such directions, components or both may be flipped, rotated, moved in space, placed in a diagonal orientation or position, placed horizontally or vertically, or similarly modified.

[0155] Unless otherwise stated, the use of the expression “and / or” between the last two members of a list of options for selection indicates that a selection of one or more of the listed options is appropriate and may be made.

[0156] The word “exemplary” is used herein to mean “serving as an example, instance or illustration”. Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and / or to exclude the incorporation of features from other embodiments.

[0157] As used herein, unless otherwise stated, adjectives such as “substantially”, “approximately” and “about” that modify a condition or relationship characteristic of a feature or features of an embodiment of the present technology, are to be understood to mean that the condition or characteristic is defined to within tolerances that are acceptable for operation of the embodiment for an application for which it is intended, or within variations expected from the measurement being performed and / or from the measuring instrument being used. When the term “about” and “approximately” precedes a numerical value, it is intended to indicate + / - 15%, or + / -10%, or even only + / -5%, and in some instances the precise value. Furthermore, unless otherwise stated, the terms (e.g., numbers) used in this disclosure, even without such adjectives, should be construed as having tolerances which may depart from the precise meaning of the relevant term but would enable the invention or the relevant portion thereof to operate and function as described, and as understood by a person skilled in the art. Unless otherwise stated, when the outer bounds of a range with respect to a feature of an embodiment of the present technology are noted in the disclosure, it should be understood that in the embodiment, the possible values of the feature may include the noted outer bounds as well as values in between the noted outer bounds.

[0158] To the extent necessary to understand or complete the disclosure of the present disclosure, all publications, patents, and patent applications mentioned herein, including in particular the applications of the Applicant, are expressly incorporated by reference in their entirety by reference as is fully set forth herein.

Claims

CLAIMS1. Apparatus for transferring patterns (410) carried by a web (14, 100) of a deformable plastics material onto substrates (10), the apparatus comprising a nip (40) defined between at least one nip roller (22) and a backing support (42) through which the substrates are passed simultaneously with the web and by means of which pressure is applied to effect transfer of the patterns (410) from the web to the substrates, characterized by a web heater (114) and a web tensioner (110) arranged upstream of the nip, and a control unit (120) arranged to control the web heater and the web tensioner in dependence upon data indicative of the lengths and widths of the patterns on the web prior to transfer, or of the patterns on the substrates after transfer, so as to ensure that, after transfer to the substrates, the patterns conform to a desired length and width.

2. Apparatus as claimed in claim 1, comprising at least one sensor (70) for taking measurements indicative of the widths and lengths of the patterns (410) on the web (14, 100) immediately before the transfer at a position upstream of the nip (40).

3. Apparatus as claimed in claim 1 or claim 2, comprising at least one sensor (80) for taking measurements indicative of the widths and lengths of the patterns (410) on the substrates (10) after the transfer at the nip (40).

4. Apparatus as claimed in claim 2 or claim 3, wherein the or each sensor (70, 80) comprises an optical sensor (122) for determining the positions of specific markings on the web on opposite sides of the web (100), the markings being either fiducials (420, 430) distinct from the patterns, or elements (440) of the patterns (410), so as to provide a measurement indicative of the width of the patterns on the web or the substrates (10).

5. Apparatus as claimed in claim 4, wherein the nip roller (22) is associated with a shaft encoder capable of measuring the movement of the web (100) and the substrates (10) through the nip (40), the length of web passing through the nip between detection by at least one optical sensor (122) of consecutive specific markings (420, 430) on the web being indicative of the length of the patterns on the web or the substrates.

6. Apparatus as claimed in any one of claim 1 to claim 5, wherein measurements of the length and width of the patterns (410) are carried out at the time of manufacture of the web (100) and encoded data markings (420, 430) are applied to the web during manufacture containing data indicative of the sizes of the patterns, and wherein the control unit (120) of theapparatus serves to set the web temperature and tension based on the data read from the web.

7. Apparatus as claimed in claim 6, wherein the encoded data markings (420, 430) indicate the optimum web temperature and web tension to be set by the control unit (120) prior to the time of the transfer of the patterns (410) to the substrates (10).

8. Apparatus as claimed in any one of claim 1 to claim 7, wherein the web heater is a heated roller (114) located upstream of the nip (40).

9. Apparatus as claimed in any one of claim 1 to claim 8, wherein at least one of the at least one nip roller (22) includes a heater.

10. Apparatus as claimed in any one of claim 1 to claim 9, wherein tension in the web is variable by control of the speed or torque of motors driving two spaced nip rollers (22) serving to advance the web (14, 100).

11. Apparatus as claimed in any one of claim 1 to claim 10, wherein the backing support (42) is a second nip roller (22).

12. Apparatus as claimed in any one of claim 1 to claim 11, further comprising upstream of the nip at least one of: a) a web guiding system (17); b) a substrate supplying device (12); c) a drive mechanism (90) for transporting the substrates (10) to the nip (40); d) a substrate inspection station (60); e) a substrate selection station (62); f) a substrate speed modifying station (64): g) a substrate heating station (52); and h) a substrate alignment device (50), said device being capable of laterally and / or rotatably displacing the substrate with respect to the nip.

13. Apparatus as claimed in any one of claim 1 to claim 12, further comprising downstream of the nip at least one of: i) a cooling station (23) for cooling the web (14, 100) and / or the substrates (10) whilst attached one to the other; ii) a separation device (30) for peeling the web away from the substrates; iii) a cutting device for slitting the web between one or more substrates; andiv) a finishing station.

14. Apparatus as claimed in any one of claim 1 to claim 13, wherein the patterns (410) include at least one transferable composition carried within recesses in and / or on a first surface of the web.

15. Apparatus as claimed in claim 14, wherein the web (14, 100) is made of one or more layers of plastics material and has at least the first surface made of a formable thermoplastic polymer.

16. Apparatus as claimed in any one of claim 1 to claim 15, wherein the patterns (410) are made of one or more transferable compositions containing particles of one or more materials and an adhesive being activatable by heat and / or by pressure.

17. Apparatus as claimed in claim 16, wherein the patterns (410) are, or can be rendered, conductive and at least part of the particles is made of an electrically conductive material.

18. A method of ensuring that patterns carried by a web of a deformable plastics material conform to a desired length and / or width following transfer of the patterns to a substrate at a transfer nip that comprises a rotatable nip roller and at which the web and the substrate are pressed against one another, the method including: a) collecting data indicative of at least one of the lengths and widths of the patterns(i) on the web prior to transfer of the patterns to the substrates, and / or(ii) on the substrate following transfer of the patterns to the substrates, and b) controlling at least one of a temperature and a tension of the web upstream of, or at, the nip in dependence upon the collected data.

19. A method as claimed in claim 18, wherein the data indicative of the lengths and / or the widths of the patterns is collected by at least one sensor disposed along the web upstream and / or downstream of the nip.

20. A method as claimed in claim 19, wherein the data indicative of the lengths and / or widths of the patterns is derived from detection by the or each sensor of two or more markings selected from elements of the patterns and fiducials distinct from the patterns.

21. A method as claimed in any one of claim 18 to claim 20, which method further comprises providing a shaft encoder associated with the nip roller, the encoder being capable of measuring the movement of the web and the substrates through the transfer nip, the length of web passing through the nip between detection of consecutive specific markings beingindicative of the length of the patterns on the web or the substrates.

22. A method as claimed in any one of claim 18 to claim 21, wherein the lengths and / or widths of the patterns are measured during manufacture of the web and data are placed on the web to indicate the optimum temperature and tension of the web during transfer of the patterns to the substrates, and wherein at least one of a temperature and a tension of the web upstream of, or at, the transfer nip is controlled during transfer of the patterns to the substrates based on the data read from the web.

23. A method as claimed in any one of claim 18 to claim 22, wherein a) varying the temperature in the web is controlled by heating the web upstream of, and / or at, the transfer nip; and / or b) varying the tension in the web is controlled by varying the speed or torque of motors driving two spaced rollers serving to advance the web towards the nip.

24. A method as claimed in any one of claim 18 to claim 23, wherein the substrates are fed to the nip by a substrate supplying device and a drive mechanism for transporting the substrates to the transfer nip where the substrates are aligned prior to entry of the substrates into the nip, the method optionally including, prior to said entry, one or more of: a) inspecting the substrates for defects; b) selecting the substrates substantially free of defects; c) modifying the speed of the substrates; and d) heating the substrates.

25. A method as claimed in claim 24, wherein the alignment of the substrates includes setting at least the Y-position of the substrates with respect to the transfer nip and / or rotating the substrates, said alignment being optionally performed by lateral abutments.

26. A method as claimed in any one of claim 18 to claim 25, further comprising laterally guiding the web prior to entry into the transfer nip.

Images