CN110710001A

CN110710001A - Apparatus, screen printing device, system and method for screen printing on a substrate for manufacturing solar cells

Info

Publication number: CN110710001A
Application number: CN201780091363.2A
Authority: CN
Inventors: 达维德·科莱; 马可·加里亚佐; 乔治·塞莱尔
Original assignee: Applied Materials Baccini SpA
Current assignee: Applied Materials Italia SRL
Priority date: 2017-05-30
Filing date: 2017-05-30
Publication date: 2020-01-17
Also published as: WO2018219434A1

Abstract

The present disclosure provides an apparatus (100) for screen printing on a substrate (10) for manufacturing a solar cell. The apparatus (100) comprises a detection device (110) and a positioning device (120), the detection device (110) being configured to read an identification member (220) on one or more screen devices (200) to obtain information about one or more characteristics of the one or more screen devices (200), and the positioning device (120) being configured to position the one or more screen devices (200) relative to at least one of the substrate (10) and the line pattern on the substrate (10) based on the one or more characteristics obtained by the detection device (110).

Description

Apparatus, screen printing device, system and method for screen printing on a substrate for manufacturing solar cells

Technical Field

Embodiments of the present disclosure relate to an apparatus for screen printing on a substrate for manufacturing a solar cell, a screen device for screen printing on a substrate for manufacturing a solar cell, a system for screen printing on a substrate for manufacturing a solar cell, and a method for screen printing on a substrate for manufacturing a solar cell. Embodiments of the present disclosure relate to, inter alia, apparatuses, screen devices, systems and methods for printing line patterns, such as finger lines (fingers) and/or busbars (busbars), of solar cells.

Background

Solar cells are Photovoltaic (PV) devices that convert sunlight directly into electrical energy. In this field, it is known to use printing techniques, such as screen printing, to produce solar cells on a substrate, such as a crystalline silicon substrate, so as to realize a structure of a pattern of conductive lines on one or more surfaces of the solar cell. The line pattern may then be printed in a plurality of printing processes, for example using a plurality of printing stations and screen devices. In view of the quality of the manufactured solar cell, the printed line patterns should be aligned with respect to the substrate and/or with respect to each other in the printing process. For example, the alignment of the line patterns with respect to each other may affect electrical characteristics, such as the conductivity of the line patterns and/or the output power of the fabricated solar cell.

In view of the above, new apparatus, screen devices, systems and methods for screen printing on substrates for manufacturing solar cells that overcome at least some of the problems in the art would be beneficial. In particular, the present disclosure aims to provide an apparatus, a screen device, a system and a method which allow improved alignment of the printing tracks with respect to the substrate and/or each other.

Disclosure of Invention

In view of the above, an apparatus, a screen device, a system and a method for screen printing on a substrate for manufacturing a solar cell are provided. Other aspects, benefits and features of the present disclosure will be apparent from the claims, description and drawings.

According to an aspect of the present disclosure, there is provided an apparatus for screen printing on a substrate for manufacturing a solar cell. The apparatus comprises a detection device configured to identify (e.g. read) an identification member on one or more screen devices to obtain information about one or more characteristics of the one or more screen devices, and a positioning device configured to position the one or more screen devices relative to at least one of the substrate and the line pattern on the substrate based on the one or more characteristics obtained by the detection device.

According to an aspect of the present disclosure, there is provided an apparatus for screen printing on a substrate for manufacturing a solar cell. The apparatus comprises a detection device configured to identify (e.g. read) an identification member on one or more screen devices to obtain information about one or more characteristics of the one or more screen devices, and a controller configured to select the one or more screen devices for a printing process based on the one or more characteristics obtained by the detection device.

According to a further aspect of the present disclosure, there is provided a screen printing apparatus for screen printing on a substrate for manufacturing a solar cell. The screen device includes one or more apertures defining a line pattern to be deposited over the substrate and an identification member, wherein the identification member is configured to provide access to one or more characteristics of the screen device.

According to another aspect of the present disclosure, a system for screen printing on a substrate for fabricating a solar cell is provided. The system comprises an apparatus according to the present disclosure and a screen unit.

According to yet another aspect of the present disclosure, a method for screen printing on a substrate for fabricating a solar cell is provided. The method comprises the following steps: identifying (e.g., reading) identifying members on one or more screen devices to obtain information about one or more characteristics of the one or more screen devices, and at least one of selecting and aligning the one or more screen devices with respect to at least one of the substrate and the line pattern on the substrate based on the obtained information about the one or more characteristics.

Embodiments are also directed to apparatuses for performing the disclosed methods and include apparatus portions for performing each of the described method aspects. The method aspects may be performed by hardware components, a computer programmed by appropriate software, by any combination of the two, or in any other manner. Furthermore, embodiments according to the present disclosure also relate to a method for operating the device. It includes method aspects for performing each function of the device.

Drawings

So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and describe the same as follows:

fig. 1 shows a schematic view of an apparatus for screen printing on a substrate for manufacturing solar cells according to embodiments described herein;

fig. 2 shows a schematic view of a screen printing screen arrangement on a substrate for manufacturing a solar cell according to embodiments described herein;

3A-3C illustrate schematic views of apertures and lines of a screen apparatus according to embodiments described herein;

fig. 4A and 4B show mesh pairings according to embodiments described herein;

FIG. 5 illustrates a screen having a line pattern according to embodiments described herein;

FIG. 6 illustrates apertures and nodes of a wire mesh according to embodiments described herein;

FIG. 7 shows a screen pairing and dual printing process according to embodiments described herein;

FIG. 8 shows a schematic diagram of a system for screen printing on a substrate for fabricating a solar cell according to embodiments described herein; and

fig. 9 shows a flow diagram of a method for screen printing on a substrate for manufacturing a solar cell according to embodiments described herein.

Detailed Description

Reference will now be made in detail to the various embodiments of the disclosure, one or more examples of which are illustrated in the figures. In the following description of the drawings, like reference numerals refer to like parts. Generally, only the differences with respect to the individual embodiments are described. Each example is provided by way of explanation of the disclosure, and is not meant as a limitation of the disclosure. Furthermore, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the present description include such modifications and variations.

The solar cell has a structure of a conductive wire pattern, such as fingers and bus bars. The high conductivity of the line pattern may be beneficial for improving the electrical characteristics of the solar cell. Furthermore, the line width of the fingers has decreased over the past few years, increasing the likelihood of narrow line breaks.

The present disclosure uses one or more characteristics of one or more screen devices used to form a line pattern during a screen printing process to select and/or align the one or more screen devices. For example, one or more characteristics may be associated with the apertures of a screen device and/or the screens (wire mesh) within the apertures that define the line pattern. In multi-printing, such as dual printing, two or more screen devices may be paired based on one or more characteristics obtained for each of the two or more screen devices in order to ensure optimal printing results, and in particular optimal matching between the line patterns printed on top of each other. Additionally or alternatively, the screen device may be aligned relative to the substrate and/or the line pattern previously printed on the substrate, for example by applying an offset to the screen device based on one or more characteristics to ensure optimum printing results.

In view of the above, appropriate selection and/or alignment of one or more screen devices may improve the quality of the printed line pattern. In particular, the interruption of the line pattern can be avoided. In addition, electrical characteristics of the line pattern, such as conductivity, may be improved.

Fig. 1 shows a schematic view of an apparatus 100 for screen printing on a substrate 10 for manufacturing solar cells according to embodiments described herein. The apparatus 100 may be configured for multi-printing, such as dual printing, e.g., Fine Line Dual Printing (FLDP).

The apparatus 100 comprises a detection device 110 and a positioning device 120, the detection device 110 being configured to recognize (e.g. read) the identification member 220 on one or more screen devices 200 ("smart screen") to obtain information about one or more characteristics of the one or more screen devices, and the positioning device 120 being configured to position the one or more screen devices 200 relative to the substrate 10 and at least one of the line patterns on the substrate 10 based on the one or more characteristics obtained by the detection device 110. For example, the positioning device 120, which may be or may include a controller, may be configured to select and position one or more screen devices 200 based on the obtained information. Additionally or alternatively, the positioning device 120 may be configured to align one or more screen devices 200 based on the obtained information.

According to some embodiments, which can be combined with other embodiments described herein, one or more characteristics can be selected from the group consisting of geometric properties of one or more of the screen devices 200, classification of one or more of the screen devices 200, layout properties, and application properties of one or more of the screen devices 200. The geometric properties may be associated with the apertures of the respective screen devices and/or the screens within the apertures that define the line pattern. For example, the geometric property can be selected from the group consisting of the position of one or more apertures, the position of a node of a line structure in one or more apertures, the angle between a line of the web and an aperture, and the position of a line web portion of the web from which the reference line web stock is supplied. However, the present disclosure is not so limited, and the geometric property may be other geometric properties suitable for the intended purpose, such as all properties related to the geometry of the screen. The categories may include screen categories, such as precision categories and/or offset/opening categories, and types of line patterns to be printed on the substrate. The layout properties may include (or data related to) the hole layout of the screen and/or the properties of the solar cell layout. The application properties may include properties of (or data relating to) emulsification of the printing material and/or the screen device.

The data about the printed material may include information about at least one of: (a) identification of printing paste along with a screen that has been tested/qualified by the screen supplier; (b) identification of the printing paste by one or more of the paste supplier, model type, supplier code, customized code (e.g., agreed upon by the paste supplier, user, and screen supplier), and the like.

The property regarding emulsification may include at least one of the following items: (a) emulsion type, (b) thickness of the over-mesh (i.e., thickness of the emulsion exceeding the thickness of the wire) on the blade side and on the wafer side, and (c) tapering of the cross-section of the holes on the screen. Tapering can be achieved by adjusting the emulsification process. The manufacturer can determine different values for the openings on the blade side and on the wafer side. For example, the nominal openings of the fingers (holes) of the screen may be 35 μm, the wafer side openings may be 38 μm, and the squeegee side may be 32 μm.

According to some embodiments, a screen class (particularly an accuracy class) may be used to match the solar cell layout for dual printing. The offset/aperture classes can be used to establish a correlation between one or more apertures and the position of the wire mesh (especially the position of the nodes of the wire mesh). Sorting, matching and pairing of the screens is illustrated in fig. 4 to 7.

In some embodiments, the one or more characteristics may include, for example, data related to manufacturing the web. For example, the one or more characteristics may include at least one of screen data, screen category, and layout properties. The screen data may include data relating to two-dimensional geometry and/or data relating to non-two-dimensional geometry. In some embodiments, the non-two-dimensional geometric elements may be selected from the group consisting of layer compositions, emulsified thickness over a web (referred to as "EOM"), wire-calendering, and the like. For example, the screen data may include data regarding one or more apertures (also referred to as "openings"), printing material, emulsification of the screen device, and the like. The layout data may include a digital scan, such as jpeg, of the corresponding layout. The layout data may include one or more of the following items: (a) vector graphics of the printed pattern (e.g., a CAD file in dxf (dwg) format), (b) high-precision image scans obtained by an automated microscope system (such as Vertex Micro-Vu; formatted JPG/BMP or others; the image may be high resolution), and (c) low-resolution pictures JPG/BMP for immediate identification of the pattern type. In particular, the layout data may include some or all of the geometric characteristics that may be represented by the two-dimensional scan.

In some embodiments, the apparatus 100 (and in particular the positioning device 120) may be configured to select one or more of the screen devices 200 based on one or more characteristics (such as classification). For example, the apparatus 100 may be configured to select two or more screens of one or more screen devices 200 for a multi-print process on the substrate 10 based on one or more characteristics obtained by the detection device 110. For example, the apparatus 100 is configured to select two screen devices for a dual printing process. The two screen units may be paired or combined based on one or more characteristics in order to achieve the best printing results. This selection may be done automatically by the system, or the operator may manually scan the screens with the mobile device, and the system may for example indicate which screens to select for performing the double printing.

According to some embodiments, a plurality of screen devices (e.g., a screen inventory) may be provided, such as a first screen device, a second screen device, and a third screen device. A first screen device may be used to print a first line pattern on the substrate 10 and a second screen device may be used to print a second line pattern over the first line pattern. The first and second line patterns may together form fingers and/or busbars of the solar cell. However, the present disclosure is not limited thereto, and the same screen device may be used to print both the first and second line patterns.

In order to provide the best match between the first and second line patterns, the apparatus 100 may be configured to select one or more screen devices by determining a match between the plurality of screen devices based on the one or more characteristics obtained for each of the plurality of screen devices. For example, the first screen unit may not match the second screen unit or the third screen unit, and the second screen unit may match the third screen unit. The second and third screen units may be selected and paired and may be used, for example, for a double printing process. The overlapping of the first and second line patterns may be provided without magnification, such as finger magnification, thereby improving the quality of the printing process.

According to embodiments, which can be combined with other embodiments described herein, the apparatus 100 (in particular the positioning device 120) can be configured to align one or more screen devices 200 based on one or more characteristics (such as geometrical characteristics and/or classification) of the one or more screen devices 200. For example, the positioning device 120 may be configured to align the one or more screen devices 200 with respect to the substrate 10 and at least one of the line patterns (such as the first line pattern) on the substrate 10 based on the one or more characteristics obtained by the detection device. For example, the positioning device 120 may be configured to align one or more screen devices 200 for a dual printing process to form fingers and/or busbars of solar cells, for example. One or more of the screen units 200 may be aligned based on one or more characteristics in order to achieve optimal printing results. The same screen device may be used for a dual printing process, e.g. for printing two or more line patterns on top of each other. For example, after printing the first line pattern, the screen device may be aligned (e.g. offset) with respect to the first line pattern based on one or more characteristics of the screen device in order to ensure an optimal printing result.

The database, which may be a web-based database, may include one or more characteristics of one or more of the screen apparatuses 200. The database may be network-based and accessible by a remote connection. In this case, the data may be downloaded by the system. In other embodiments, the database may be local to the system. The data may be updated using, for example, an upload from the USB device or another dependent storage medium. One or more characteristics or data regarding one or more characteristics may be downloaded by reading an identification member 220 (such as a bar code) provided on the screen device. The identification member 220 may be one of a bar code, an RFID device, and an identification code. Reading can be accomplished by RF interface, bar code laser scanning, optical inspection by a vision system, and the like. The apparatus 100 may, for example, match the screen devices for optimal positioning of the second line pattern relative to the first line pattern in a dual printing process and/or may assign a score to a selected pair of screen devices.

The score may be assigned in relation to the expected outcome of the web match on device performance. If the screen Axx matches the screen Ayy, the score dispensed is the best score: 100 percent. The following table shows examples of classifications.

Screen mesh numbering	Classification
		1	L23
2	B36
		3	E30
4	A17

A match between the a17 screen and the B36 screen may yield a fraction of about 90%. A match between the a17 screen and the L23 screen may result in a fraction of about 15%. Different letters (A, B.. L) determine the score of the match. In this case, the system has a limited effect on the results of improving the efficiency of the device. Since the system can compensate with an offset, different numbers do not affect the score. It is to be understood that the foregoing classifications are exemplary only. Other possibilities of increasing the classification based on the web properties may be used, such as the angle formed by the lines and holes.

According to some embodiments, which can be combined with other embodiments described herein, the detection device 110 comprises or is a reader, such as a bar code reader, configured to read the identification means 220 to obtain information about one or more characteristics. The detection device 110 may be on board the system or on a mobile device connected to the system. For example, an operator may use a moving device to scan the screen. The identification member 220 may be selected from the group consisting of a barcode, an RFID (radio frequency identification) chip, an identification code, and any combination thereof. Reading can be accomplished by RF interface, bar code laser scanning, optical inspection by a vision system, and the like.

The present disclosure is not limited to a reader, and the detection device 110 may be another device configured to recognize the identification means 220. For example, the detection device 110 may include or be an optical device, such as a vision system. For example, a CCD camera may be used to find a particular feature/code on the web.

In some embodiments, the identification component 220 includes (e.g., stores) information about one or more characteristics, and in particular includes (e.g., stores) one or more characteristics. In other words, the apparatus 100 may retrieve the one or more characteristics directly from the identification component 220. For example, the RFID chip may include a storage medium configured to store one or more characteristics, such as a classification and/or a geometric property of the web.

In a further embodiment, the apparatus 100 comprises a communication unit 130 configured to communicate with a database, such as a server (e.g. shown in fig. 4), to obtain information about one or more characteristics from the database. The database includes (e.g., stores) one or more characteristics. The database may be a web-based database. For example, the communication between the communication unit 130 and the database may be performed via a network such as the Internet (Internet). The identifying means 220 may include (e.g., store) information, such as access information for accessing a database to retrieve one or more characteristics. In other words, the device 100 may use the access information provided by the identification component 220 to retrieve one or more characteristics from the database.

According to some embodiments, which can be combined with other embodiments described herein, the apparatus 100 can be configured to perform multiple printing, such as dual printing, on the substrate 10. In particular, the apparatus 100 may be configured to print fingers and/or busbars of solar cells using a multi-print process.

In a multiple printing process, two or more layers (or line patterns) may be printed on top of each other using two different screen devices or the same screen device to form the fingers and/or busbars. For example, a first layer (e.g., a first line pattern) of two or more layers may be printed directly on the substrate 10 using a first screen device. A second layer (e.g., a second pattern of lines) of the two or more layers may be printed on the first layer and especially directly on the first layer using either the first screen device or the second screen device. The printing material used for multiple prints may comprise or be silver. According to some embodiments, which can be combined with other embodiments described herein, the printing material can be selected from the group consisting of silver, aluminum, copper, tin, nickel, silicon-based paste, and any combination of the above.

According to some embodiments, in the above-described duplex printing, one or more of the screen devices 200 may be two or more screen devices including a first screen device and a second screen device. The first screen device may have a first identification means configured to provide access to the one or more first characteristics relative to the one or more apertures of the first screen device. The second screen device may have a second identification means configured to provide access to the one or more second characteristics relative to the one or more apertures of the second screen device. The positioning device may be configured to perform at least one of selecting the first screen device and aligning the first screen device with respect to the substrate 10 based on the one or more first characteristics obtained by the detection device 110 for depositing the first line pattern. The positioning device 120 may be configured to at least one of select a second screen device and align the second screen device relative to the first line pattern based on the one or more second characteristics obtained by the detection device 110 for depositing a second line pattern over the first line pattern.

In some embodiments, the width of the finger line formed by the first line pattern and the second line pattern superimposed on the first line pattern may be less than 100 micrometers, specifically less than 80 micrometers, and more specifically less than 60 micrometers. The thickness of the finger lines formed by the first line pattern and the second line pattern superimposed on the first line pattern may be greater than 15 microns, specifically greater than 20 microns, and more specifically greater than 30 microns.

In some embodiments, the indication of the finger width and height may be considered qualitative. In particular, for single print, the prior art finger line width may be 45-50 μm. The double printing is slightly lower, such as about 40-45 μm. With regard to the finger line height, it is considered that the lower the width, the lower the height for a single print. For single prints of 45-50 μm, it may be about 15-20 μm. Dual printing can achieve the same or higher height at lower widths.

When referring to the term "over.," (e.g. the second line pattern is over the first line pattern), it is to be understood that, starting from the substrate 10, the first line pattern is printed over the substrate 10 and the second line pattern to be printed after the first line pattern is thus printed over the first line pattern and over the substrate 10. In other words, the term "over. This is independent of whether the substrate 10 or the solar cell is depicted upside down.

According to some embodiments, the second line pattern is superimposed on (or coincident with) the first line pattern. For example, the second line pattern is not printed on the substrate 10, but is completely printed over the first line pattern. In other embodiments, the second line pattern is partially superimposed on the first line pattern. For example, the second line pattern may be offset with respect to the first line pattern.

The substrate 10 according to embodiments described herein may comprise at least one of an electrically conductive material (especially with silicon or aluminum), a plate, a wafer, a foil, a semiconductor wafer, a solar cell wafer, a silicon solar cell wafer, or a green sheet circuit board (especially useful for forming solar cells).

Fig. 2 shows a schematic view of a screen printing device 200 for screen printing on a substrate for manufacturing a solar cell according to embodiments described herein.

The screen device 200 includes one or more apertures 215 that define a line pattern, such as a first line pattern and/or a second line pattern, to be deposited on a substrate and an identifying member 220, wherein the identifying member 220 is configured to provide access to one or more characteristics of the screen device 200. As described with respect to fig. 1, the one or more characteristics may be selected from the group consisting of one or more geometric properties of the screen apparatus 200, one or more classifications of the screen apparatus 200, layout properties, and one or more application properties of the screen apparatus 200.

In some embodiments, the wire mesh device 200 can include a frame 210 and a wire mesh attached to the frame 210. The identification member 220 may be provided at the frame 210. For example, the identification member 220 may be attached to or embedded in the frame 210. A bar code may be printed or snapped, for example, onto the frame 210. Similarly, an RFID chip may be affixed to or embedded within the frame 210.

The screen may include at least one of a net, a printing mask, a sheet, a metal sheet, a plastic sheet, a plate, a metal plate, and a plastic plate. In some embodiments, the screen defines a pattern corresponding to the structure to be printed on the substrate, wherein the pattern may include one or more apertures 215. The pattern may correspond to a pattern of conductive lines to be printed on the substrate 10, such as fingers and/or busbars of a solar cell. For example, the screen apparatus 200, and particularly the screen, may have one or more apertures defining a pattern of conductors and a screen provided within the one or more apertures. For example, the material to be deposited on the substrate 10 may be provided as a substantially uniform layer on the screen by using a water knife (flodebar). Due to the presence of the wire mesh, material does not flow through the one or more holes 215. During the deposition process, the squeegee may exert a force or pressure on the material and push the material through the one or more apertures such that the material is transferred to (i.e., deposited on) the substrate 10.

Fig. 3A-3C show schematic views of a hole 310 and a line 320 (such as a finger line or a bus bar) according to embodiments described herein. The lines 320 of the first line pattern are exemplarily shown deposited on the substrate 10, wherein another line (not shown) of the second line pattern may be printed over the lines 320 of the first line pattern.

According to some embodiments, which can be combined with other embodiments described herein, the wire mesh device comprises a wire structure, such as a mesh or net, within one or more apertures. For example, the line structure may be provided by a plurality of first lines 312 extending in a first direction and a plurality of second lines 314 extending in a second direction different from the first direction. The wire structure may be a woven mesh or a wire mesh. The diameter of the plurality of first lines 312 and the plurality of second lines 314 may be in the range of 10 to 30 micrometers, and specifically in the range of 15 to 20 micrometers. The plurality of first lines 312 and the plurality of second lines 314 may cross each other to define a plurality of openings 316 therebetween. The size of the openings 316 (e.g., the pitch of the mesh) may be in the range of 1 to 500 microns, specifically in the range of 10 to 150 microns, and more specifically in the range of 15 to 100 microns. For example, the size may be about 60 microns. In some embodiments, the 325-16 wire mesh is characterized by 325 wires per inch, and each wire can have a diameter of 16 μm. Thus, the opening 316 may be "calculated" to be 25.4mm/325-0.016 mm-0.062 mm. In other embodiments, in the case of a 500-16 mesh, the openings may be 25.4mm/500-0.016mm ═ 0.035 mm. Other meshes are possible, such as 380-14 (380 wires per inch with a diameter of 14 μm) and 440-13 (440 wires per inch with a diameter of 13 μm).

In some embodiments, the first direction and the second direction may be substantially perpendicular to each other. The term "substantially perpendicular" relates to a substantially perpendicular orientation of, for example, a first direction and a second direction, wherein deviations of a few degrees from the exact perpendicular orientation (e.g. up to 10 ° or even up to 15 °) are still considered to be "substantially perpendicular". In some embodiments, the line may have an angle of 80 °. According to some embodiments, the first direction and/or the second direction may be inclined with respect to a longitudinal extension of the hole 310 and/or a length direction of a line 320 defined by the hole 310 (such as a length direction of a finger line or a busbar). For example, the first and second directions may be inclined at an angle in the range of about 20 degrees to about 60 degrees with respect to the longitudinal extension of the bore 310. For example, the first and second directions may be tilted by about 22.5 degrees, about 30 degrees, or about 45 degrees. The line structure may include a plurality of nodes 318. The nodes may be defined by lines of a cross-line structure, such as a cross between the plurality of first lines 312 and the plurality of second lines 314.

Although fig. 3A shows a mesh that is angled with respect to the length direction of the apertures, it is to be understood that the present disclosure is not so limited. For example, the line structure may be substantially parallel to the aperture. In this case, the irregularity in finger height (see fig. 3C) will not be caused by a line node, but by a line.

In some embodiments, the node positions perpendicular to the length direction of the line 320 (such as the finger direction) may vary. The connecting lines along and connecting the nodes may have a constant angle. Changes in node position can affect the shape of the printed line. According to some embodiments, the one or more characteristics of the screen device may comprise geometrical characteristics or information about the position of the nodes in the holes and/or information about the position of the holes on the screen. Irregularities caused by the nodes 318 may be smoothed or even eliminated by selecting an appropriate alignment for the screen device based on one or more characteristics, such as the location of the nodes in the hole, for printing a second line pattern over the first line pattern.

Fig. 3B shows a top view of a line 320 (such as a finger line) formed using the hole 310 of fig. 3A. Fig. 3C shows a cross-sectional side view (i.e., profile) of line 320 of fig. 3B. The lines 320 may be irregular shapes caused by the structure of the screen device, and in particular the line structures provided in the holes 310 as shown in fig. 3A.

As shown in fig. 3B, a line width, such as a finger line width, may vary along the extended length of line 320. Further, as shown in fig. 3C, the wire 320 may have varying thicknesses. For example, the line width and/or line thickness may vary by approximately sinusoidal. The line width may have a maximum value (maximum width) and a minimum value (minimum width). Likewise, the line thickness may have a maximum value (peak; maximum height or thickness) and a minimum value (valley; minimum height or thickness). The maxima and minima may have a periodicity corresponding to the spacing between nodes 318 of a wire structure, such as a wire mesh. In particular, there may be a correlation between (i) the location of node 318 along hole 310, (ii) the shape of line 320 on substrate 10 (footprint), and (iii) the roughness of the finger defined by the peaks and valleys.

The present disclosure may smooth the contours and/or thickness of the patterns printed on top of each other, such as a second line pattern printed on top of the first line pattern, to form fingers and/or busbars of the solar cell. In particular, one or more screen devices are positioned relative to at least one of the substrate and the first line pattern on the substrate based on one or more characteristics (such as node positions) obtained by the detection device. For example, the screen device used to print the second line pattern may be selected and/or positioned such that the width variation and/or thickness variation is smooth (even out). In some embodiments, the minimum value of the second line pattern may be positioned above the maximum value of the first line pattern, and the maximum value of the second line pattern may be positioned above the minimum value of the first line pattern. The screen device used for printing the second line pattern may be the same screen device as used for printing the first line pattern or another screen device.

According to some embodiments, the apparatus is configured to select and optionally align at least one of the one or more screen devices based on one or more characteristics (such as geometric properties and/or classification) of the at least one screen device. For example, the positioning device is configured to align the at least one screen device with respect to the substrate 10 and at least one of the line patterns (such as the first line pattern) on the substrate 10 based on the one or more characteristics obtained by the detection device. According to some embodiments, which can be combined with other embodiments described herein, the alignment can include applying an offset relative to a line pattern (such as a first line pattern) on the substrate 10 based on one or more characteristics obtained by the detection device. As used throughout this disclosure, the terms "offsetting" and "offset" may also be understood in the sense of "shifting" or "displacement".

In some embodiments, the offset may be selected based on at least one of one or more characteristics of a screen device used to print the first line pattern and one or more characteristics of a screen device used to print the second line pattern. Additionally or alternatively, the offset may be selected based on a periodicity of the width variation and/or the thickness variation of the first line pattern and/or the second line pattern. For example, the offset may correspond to a periodicity of the width variation and/or the thickness variation of the first line pattern. According to some embodiments, the periodicity of the first line pattern may be derived from one or more characteristics of a screen device used for printing the first line pattern. In further embodiments, for example, the periodicity of the first line pattern may be measured in-situ between a first printing process for printing the first line pattern and a second printing process for printing the second line pattern. The periodicity thus determined may then be used to apply a predetermined offset for the second printing process.

In further embodiments, the system may incrementally vary the offset and find the value that gives the best device performance. The system may apply incremental shifts to successive cells of a subsequent batch, such as a 10 μm shift to 500 cells of a first batch, a 20 μm shift to 500 cells of a second batch, and so on. The batch of wafers may be tracked along the equipment until a test portion of the electrical property is measured. The lot with the best electronic result (e.g., best device performance, such as battery efficiency) may be the lot from which the offset is to be selected for production.

According to some embodiments, which can be combined with other embodiments described herein, the same screen device can be used for printing the first and second line patterns. For example, a first line pattern may be printed on the substrate 10 in a first printing process using a screen device. The substrate 10 and the screen device may be offset with respect to each other and the second line pattern may be printed over the first line pattern in a second printing process using the screen device (i.e. the same screen device). However, the present disclosure is not limited thereto, and alignment using offset may be applied to a multi-printing process using different screen devices (such as a first screen device and a second screen device) to print line patterns on top of each other.

Interruptions in the printed line pattern can be reduced or even avoided by offsetting (transferring, displacing) the substrate 10 and the screen device relative to each other after the first printing process and before the second printing process. For example, there may be interruptions in the first line pattern printed in the first printing process when the screen portion is obstructed by the (dry) printing material. The second line pattern may also have interruptions when the same screen portion is still obstructed in the second printing process. However, this break in the second line pattern will be offset with respect to the break in the first line pattern. In other words, the second line pattern provides a bridge over the interruption in the first line pattern, and there is no interruption in the printed line pattern (e.g. in the fingers of the solar cell). This may increase the efficiency of the manufactured solar cell.

Furthermore, offsetting the substrate 10 and the screen device relative to each other between printing processes may reduce the number of cleaning processes of the screen device, since possible interruptions in the first line pattern may be cured (bridged) by the second line pattern, and vice versa. For example, maintenance down of equipment for manufacturing solar cells may be reduced, and yield may be increased.

In some embodiments, the offset is provided in a direction substantially parallel to the first longitudinal extension of the one or more lines of the first line pattern. The one or more lines may be fingers of the solar cell. As an example, the offset is a longitudinal extension substantially parallel to the fingers of the solar cell. The term "substantially parallel" relates to, for example, an offset direction and a substantially parallel orientation referring to the longitudinal extension of the line, wherein deviations of a few degrees from the exact parallel orientation (e.g. up to 10 ° or even up to 15 °) are still considered to be "substantially parallel". The term "longitudinal extension" is to be understood as the extension of the lines of the first line pattern (and the second line pattern) in the length direction of the lines. The length of a line refers to the longer dimension of the line, wherein the width of the line refers to the shorter dimension of the line.

According to some embodiments, which can be combined with other embodiments described herein, the offset can be provided by moving the substrate 10 and the screen device relative to each other in a plane substantially parallel to the surface of the substrate 10 on which the first and second line patterns are to be printed. In some embodiments, the offset is provided by linear movement of the substrate 10 and the screen device relative to each other. The linear movement may be substantially parallel or substantially perpendicular to the longitudinal extension of the one or more lines of the first line pattern. The offset is provided, for example, by a linear movement of the substrate 10 and/or the screen arrangement substantially parallel to the longitudinal extension of the fingers of the solar cell.

According to a further embodiment, the offset is provided by a two-dimensional movement of the substrate 10 and the screen device relative to each other. The two-dimensional movement may be a movement in a plane substantially parallel to the surface of the substrate 10 on which the first and second line patterns are to be printed. The offset is provided, for example, by a two-dimensional movement of the substrate 10 and/or the screen device, wherein the movement component is substantially parallel and perpendicular to the longitudinal extension of the one or more lines of the first line pattern.

According to some embodiments, which can be combined with other embodiments described herein, the positioning device can comprise one or more actuators configured to move the screen device, for example to align the screen device and/or to offset the screen device. The one or more actuators may be selected from the group consisting of electric motors, electromagnetic motors, linear motors, stepper motors, pneumatics, piezoelectrics, and any combination thereof.

In some embodiments, the offset (e.g., the amount of displacement) in the longitudinal extension of the one or more lines of the first line pattern is in the range of 10 to 1000 microns, specifically in the range of 10 to 500 microns, and more specifically in the range of 100 to 200 microns, for example. For example, the offset may be at least 10 microns, and specifically at least 50 microns.

In some embodiments, offsetting the substrate 10 and the screen device relative to each other comprises moving the substrate 10 using, for example, a transport device such as a shuttle. The screen arrangement may be stationary while the substrate 10 is moving. For example, the first printing process and the second printing process may be performed in the same printing station. The printing station may have the screen unit in a stationary position. The substrate 10 may be moved to provide the offset using, for example, a movable substrate support on which the substrate 10 is located.

In other embodiments, offsetting the substrate 10 and the screen arrangement relative to each other comprises moving the screen arrangement. The substrate 10 may be stationary when the screen device is moved using, for example, one or more actuators. For example, the first printing process and the second printing process may be performed in the same printing station. The printing station may have a screen device movably provided therein.

Offset printing as described above may be used, for example, for Fine Line Dual Printing (FLDP) in high volume production (HVM). The benefit of achieving lower roughness compared to the baseline cell efficiency may result in increased cell efficiency and/or lower slurry deposition. In particular, applying the offset may utilize the fact that finger roughness is associated with the spacing of mesh nodes within the holes or openings. If the second print is shifted by the calculated offset along the finger direction, the overall roughness or rugosity may be lower than that of each individual print. Offset printing can be advantageously used when the same screen device is used to print multiple line patterns. However, the present disclosure is not limited thereto, and offset printing may also be applied to a process of printing a plurality of line patterns using different screen devices.

According to some embodiments, which can be combined with other embodiments described herein, the substrate 10 can be aligned with respect to the screen device before printing the first line pattern. In some embodiments, the alignment of the substrate 10 relative to the screen device prior to printing the first line pattern may be performed based on one or more characteristics of the screen device. For example, the identification member may be used to obtain a geometric characteristic associated with one or more apertures of the screen device. Alignment with respect to the substrate 10 may be accomplished based on geometric characteristics, such as the position of one or more apertures at the screen device.

Additionally or alternatively, the alignment of the substrate 10 relative to the screen device prior to printing the first line pattern may use a vision system, for example comprising one or more cameras. According to some embodiments, the method further comprises aligning the substrate 10 with respect to the screen device before printing the second line pattern. At least one of the alignment processes before printing the first and second line patterns may use a camera configured to take a picture of the substrate 10. The processing device may evaluate the position of the substrate 10 relative to, for example, at least one of the substrate support, the printing device, and the screen device. The processing device may adjust the position of at least one of the substrate 10, the substrate support and the screen device to adjust the relative position of the substrate 10 and the screen device.

Fig. 4A and 4B show mesh pairings according to embodiments described herein. The screens can be paired for a double printing process.

In fig. 4A, reference numeral 410 indicates a nominal size of a printed layout, such as a solar cell's fingers and/or busbars. The actual size may be defined by one or more apertures of the screen, or the actual size may correspond to one or more apertures of the screen. In fig. 4A (a), the actual size 412, which may be a square, is larger than the nominal size 410. In fig. 4A (b), the actual dimension 414 is smaller than the nominal dimension 410. (c) And (d) shows unconventional actual dimensions.

Figure 4B shows a screen pairing. For example, screens having an actual dimension 412 that is larger than the nominal dimension 410 may be paired. Further, screens having the actual size 416 of (c) may be paired, and screens having the actual size 418 of (d) may be paired. The screens of (a) and (b) cannot be paired.

Fig. 5 and 6 show exemplary classifications of screens. Fig. 5 illustrates a screen 500 having a line pattern 510 according to embodiments described herein. In some embodiments, the webs may be classified according to the geometry of the pattern, as shown in the following examples:

screen mesh numbering	Nominal value of "x	Measured value of "x	Classification
				1	150.000μm	150.050μm	L
2	150.000μm	150.010μm	B
				3	150.000μm	150.026μm	E
...	...	...	...
				n	150.000μm	150.005μm	A

Fig. 6 shows the holes 310 and nodes 318 of a wire mesh according to embodiments described herein. In some embodiments, the webs may be sorted according to the position of the lines, as shown in the following examples:

using the classification shown above with respect to fig. 5 and 6, the screen classification can be defined as a combination of one letter and two numbers:

screen mesh numbering	Classification
		1	L23
2	B36
		3	E30
n	A17

By knowing the classification, it is possible to match the screen as shown in fig. 7. Fig. 7 shows a dual printing process using screens matched based on classification, such as screen a17 and screen B36 with a 15 μm offset. The first print 710 and the second print 720 are formed on top of each other to form the fingers of the solar cell.

Fig. 8 shows a schematic diagram of a system 800 for screen printing on a substrate for fabricating a solar cell according to embodiments described herein.

The system 800 includes an apparatus according to the present disclosure and a screen device. The apparatus may be included at least in part in the printing station 830 of the system 800. The positioning means and optional detection means may be included in the printing station 830. In some implementations, aspects of the device may be provided at different locations within the system 800. The system 800 may further include a server 820 having a database with one or more characteristics. Communication between the devices and the server 820 may be performed via a network 810, such as the Internet (Internet).

In some embodiments, the system includes a plurality of processing stations, such as a printing station 830, a drying station 840, and one or more further processing stations 850 (such as at least one of another printing station, an inspection station, and another drying station). The screen unit is provided in the printing station 830. The drying station 840 may be configured to dry the first line pattern and/or the second line pattern printed on the substrate in the printing station 830. The drying station 840 may, for example, include an oven. The one or more further processing stations 850 may include another printing station configured to print, for example, bus bars on a substrate having finger lines printed thereon. The inspection station may be configured to perform quality control of the line patterns printed on the substrate. For example, the inspection system may include a vision system including one or more cameras. For example, the camera may take a picture of the substrate or the portion of the substrate having the line pattern printed thereon. The processing device may determine the position of the line pattern or portions of the line pattern relative to, for example, features (e.g., edges) of the substrate and/or each other. The processing device may determine the quality of the printed line pattern and optionally whether to dump the substrate.

The system 800 may include a transfer arrangement configured to move substrates between at least some of the processing stations. For example, the transfer arrangement is configured to move the substrate from the printing station 830 to the drying station 840 (represented by arrow 1) to dry the first line pattern. The transfer arrangement may be configured to move the substrate from the drying station 840 back to the printing station 830 (represented by arrow 2) to print the second line pattern. The transport arrangement may be further configured to move the substrate from the printing station 830 or the drying station 840 to one or more further processing stations 850 (represented by arrow 3) for at least one of quality control, further printing, and/or further drying processes, for example.

According to some embodiments, which can be combined with other embodiments described herein, a substrate is positioned on a substrate support, such as a movable substrate support ("shuttle"). In some embodiments, the substrate support may include a nest or other support upon which the substrate may be placed for screen printing. For printing the line pattern, a printing device, such as a squeegee, is movable relative to the substrate support along a printing direction. The transfer device may be configured to transport the movable substrate support between at least some of the processing stations.

In fig. 8, one printing station is exemplarily shown. For example, the same screen may be used in the printing station to print a first line pattern and a second line pattern over the first line pattern. However, the present disclosure is not so limited and two or more printing stations each having a respective screen device may be provided. For example, the first printing station may comprise a first screen device for printing a first line pattern, and the second printing station may comprise a second screen device for printing a second line pattern. The first and second screen devices may be paired based on one or more characteristics obtained by the detection device. In some embodiments, a screen stock may be provided, wherein the first and second screen devices are selected from the screen stock and moved to the first and second printing stations, respectively.

Fig. 9 shows a flow diagram of a method 900 for screen printing on a substrate for manufacturing a solar cell according to embodiments described herein. The method 900 may utilize apparatus and systems in accordance with the present disclosure.

The method 900 includes reading identification members on one or more screen devices to obtain information regarding one or more characteristics of the one or more screen devices at block 910, and selecting and/or aligning one or more screen devices at block 920. One or more screen devices may be aligned relative to the substrate and/or the line pattern on the substrate based on the obtained information about the one or more characteristics. According to some embodiments, the method 900 further may include accessing a database having one or more characteristics based on the identification information read from the identification component.

In some embodiments, the one or more screen devices are two or more screen devices, such as a first screen device for printing a first line pattern and a second screen device for printing a second line pattern over the first line pattern. The first and second line patterns may together form 4 exemplary fingers of the solar cell. Two or more screen devices may be selected and combined based on one or more characteristics to perform a multi-printing process on the substrate, such as a dual printing process for forming fingers and/or busbars of a solar cell. However, the present disclosure is not limited thereto, and the same screen device may be used to perform a multi-printing process.

In some embodiments, aligning at least one of the one or more screen devices includes applying an offset to at least one of the one or more screen devices relative to at least one of the substrate and a line pattern (such as a first line pattern) on the substrate. For example, the same screen device may be used for printing the first and second line patterns. Aligning the at least one screen device may comprise offsetting the at least one screen device with respect to the first line pattern. Irregularities caused by the wire web inside the holes of at least one wire web device can be compensated.

The present disclosure uses one or more characteristics of one or more screen devices used to form a line pattern during a screen printing process to select and/or align the one or more screen devices. For example, one or more characteristics may be associated with the apertures of the screen device and/or the screens within the apertures that define the line pattern. In multi-printing (such as dual printing), two or more screen devices may be paired up based on one or more characteristics obtained for each of the two or more screen devices in order to ensure optimal printing results, and in particular optimal matching between the line patterns printed on each other. Additionally or alternatively, the screen device may be aligned relative to the substrate and/or the line pattern previously printed on the substrate, for example by applying an offset to the screen device based on one or more characteristics, so as to ensure optimum printing results.

In view of the above, appropriate selection and/or alignment of one or more screen devices may improve the quality of the printed line patterns. In particular, the interruption of the line pattern can be avoided. In addition, electrical characteristics of the line pattern, such as conductivity, may be improved.

While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

1. An apparatus for screen printing on a substrate for manufacturing solar cells, comprising:

a detection device configured to recognize an identification member on one or more screen devices to obtain information about one or more characteristics of the one or more screen devices; and

a positioning device configured to position the one or more screen devices relative to at least one of the substrate and the line pattern on the substrate based on the one or more characteristics obtained by the detection device.

2. The apparatus of claim 1, wherein the one or more characteristics are selected from the group consisting of a geometric property of the one or more screen devices and a classification of the one or more screen devices.

3. The apparatus of claim 1 or 2, wherein the positioning device is configured to align at least one of the one or more screen devices relative to the substrate and at least one of the line patterns on the substrate based on the one or more characteristics obtained by the detection device.

4. The apparatus of any of claims 1 to 3, wherein the apparatus is configured to select two or more of the one or more screen devices for a multiple print process on the substrate based on the one or more characteristics obtained by the detection device.

5. The device of any one of claims 1 to 4, wherein the detection means comprises at least one of:

a reader configured to read at least one of a bar code and an RFID chip of the one or more web devices to obtain information about the one or more characteristics; and

an optical device configured to visually obtain information about the one or more characteristics.

6. The apparatus of any of claims 1 to 5, further comprising a communication unit configured to communicate with a database to obtain information about the one or more characteristics from the database.

7. A screen printing apparatus for screen printing on a substrate for manufacturing a solar cell, comprising:

one or more apertures defining a line pattern to be deposited over the substrate; and

identifying means, wherein the identifying means is configured to provide access to one or more characteristics of the screen device.

8. The screen apparatus of claim 7, further comprising wire structures within the one or more apertures.

9. A system for screen printing on a substrate for fabricating solar cells, comprising:

the apparatus of any one of claims 1 to 6; and

the screen unit of any of claims 7 to 8.

10. The system of claim 9, further comprising a server having the database, the database having the one or more characteristics.

11. The system of claim 8 or 9, wherein the one or more screen devices are two or more screen devices including a first screen device and a second screen device,

wherein the first screen device has first identification means configured to provide access to one or more first characteristics relative to one or more apertures of the first screen device,

wherein the second screen device has second identifying means configured to provide access to one or more second characteristics relative to one or more apertures of the second screen device,

wherein the positioning device is configured to at least one of select and align the first screen device relative to the substrate for depositing a first line pattern based on the one or more first characteristics obtained by the detection device, and

wherein the positioning device is configured to at least one of select and align the second screen device relative to the first line pattern for depositing a second line pattern over the first line pattern based on the one or more second characteristics obtained by the detection device.

12. A method for screen printing on a substrate for manufacturing a solar cell, comprising the steps of:

identifying an identification member on one or more screen devices to obtain information regarding one or more characteristics of the one or more screen devices; and

at least one of selecting and aligning the one or more screen devices with respect to at least one of the substrate and the line pattern on the substrate based on the obtained information about the one or more characteristics.

13. The method of claim 12, wherein the one or more screen devices are two or more screens, and wherein the two or more screen devices are selected and combined based on the one or more characteristics to perform a multi-print process on the substrate.

14. The method of any of claims 12 to 13, further comprising the step of:

accessing a database having the one or more characteristics based on the identification information read from the identification component.

15. The method of any of claims 12 to 14, wherein the step of aligning at least one of the one or more screen devices comprises the steps of:

applying an offset to the at least one screen relative to at least one of the substrate and the line pattern on the substrate.