An electrode of a solar cell, a printing stencil of the electrode, and a printing method

Abstract

Embodiments of the present invention disclose an electrode of a solar cell, a printing stencil of the electrode, and a printing method. The electrode includes main grid lines and sub-grid lines; the sub-grid lines intersect with the main grid lines; at the intersection, the sub-grid lines are stacked on top of the main grid lines; the height of the main grid lines in the intersection area is less than the height of the main grid lines in other areas. In the embodiments of the present invention, the height of the main grid lines in the intersection area is less than the height of the main grid lines in other areas, which can make the height of the intersection area of the main grid lines and sub-grid lines of the electrode basically the same as the height of other areas of the main grid lines or sub-grid lines of the electrode after the intersection, avoiding the height of the intersection area of the main grid lines and sub-grid lines of the electrode being higher than other areas of the main grid lines, thus solving the technical problem that in the prior art, due to the height of the sub-grid lines being higher than that of the main grid lines in the electrode of the solar cell, there will be a height difference, and there is an extrusion force during welding, which is likely to cause hidden cracks or fragments.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and particularly to an electrode of a solar cell, a printing screen plate of the electrode, and a printing method. Background Art

[0002] At present, silicon PN (Positive Negative, N-type semiconductor and P-type semiconductor) junction solar cells have developed into the dominant in the photovoltaic market. The production of silicon PN junction solar cells uses silicon as a substrate, makes a textured surface on the surface, then diffuses to form a PN junction, then etches the edge, and then deposits a passivation antireflection film, and finally makes electrodes through screen printing and sintering technology. At present, the method of making electrodes through screen printing and sintering technology has the advantage that the overlap printing of the sub-grid is changed to single printing, which greatly reduces the thick line problem and greatly improves the yield of the manufacturing process.

[0003] Currently, the screen plate design for making electrodes through screen printing and sintering technology is that the main grid penetrates through, and the sub-grid passes through the main grid, that is, when the sub-grid is printed, at the intersection, the sub-grid directly crosses over from the top surface of the main grid. This electrode structure is likely to cause hidden cracks or fragmentation during subsequent battery interconnection. Summary of the Invention

[0004] The present invention provides an electrode of a solar cell, a printing screen plate of the electrode, and a printing method, aiming to solve the technical problem of hidden cracks or fragmentation of the battery chip.

[0005] In a first aspect, the present invention discloses an electrode of a solar cell, the electrode including a main grid line and a sub-grid line; the sub-grid line intersects with the main grid line; at the intersection, the sub-grid line overlaps on the main grid line;

[0006] The height of the main grid line in the intersection area is less than the height of other areas of the main grid line.

[0007] Optionally, the sum of the height of the main grid line and the height of the sub-grid line in the intersection area is equal to the height of other areas of the main grid line.

[0008] Optionally, the height of the sub-grid line in the intersection area is less than the height of other areas of the sub-grid line.

[0009] In a second aspect, the present invention discloses a printing screen plate of an electrode of a solar cell, the printing screen plate including a main grid screen plate and a sub-grid screen plate;

[0010] The main grid screen plate includes a main grid frame, a main grid wire mesh installed in the main grid frame, and a main grid emulsion layer covering a part of the surface of the main grid wire mesh;

[0011] The auxiliary grid stencil includes an auxiliary grid frame, an auxiliary grid wire mesh installed within the auxiliary grid frame, and an auxiliary grid emulsion layer covering a partial surface of the auxiliary grid wire mesh;

[0012] The main grid emulsion layer includes a first region corresponding to the printing area where the main grid intersects with the auxiliary grid and a second region corresponding to other printing areas of the main grid; the thickness of the main grid emulsion layer in the first region is less than the thickness of the main grid emulsion layer in the second region.

[0013] Optionally, the sum of the thickness of the main grid emulsion layer in the first region and the thickness of the auxiliary grid emulsion layer in the corresponding auxiliary grid printing area is equal to the thickness of the main grid emulsion layer in the second region.

[0014] Optionally, the auxiliary grid emulsion layer includes a third region corresponding to the printing area where the auxiliary grid intersects with the main grid and a fourth region corresponding to other printing areas of the auxiliary grid; the thickness of the auxiliary grid emulsion layer in the third region is less than the thickness of the auxiliary grid emulsion layer in the fourth region.

[0015] Optionally, the width of the main grid printing area of the main grid stencil is greater than or equal to 38 microns and less than or equal to 42 microns, and the depth is greater than or equal to 10 microns and less than or equal to 13 microns.

[0016] Optionally, the width of the auxiliary grid printing area of the auxiliary grid stencil is greater than or equal to 27 microns and less than or equal to 29 microns, and the depth is greater than or equal to 11 microns and less than or equal to 15 microns.

[0017] Optionally, the auxiliary grid emulsion layer includes an intermediate printing area and an edge area surrounding the intermediate printing area; the thickness of the auxiliary grid emulsion layer in the edge area is greater than the thickness of the auxiliary grid emulsion layer in the intermediate printing area.

[0018] In a third aspect, the present invention discloses a printing method for an electrode of a solar cell, including the following steps:

[0019] Print the main grid lines on the battery chip using the main grid stencil; then print the auxiliary grid lines using the auxiliary grid stencil.

[0020] In an embodiment of the present invention, the height of the main grid line in the intersection area is less than the height of the main grid line in other areas, which can make the height of the intersection area of the main grid line and the auxiliary grid line of the electrode basically the same as the height of other areas of the main grid line or the auxiliary grid line of the electrode after the intersection of the main grid line and the auxiliary grid line of the electrode, avoiding the height of the intersection area of the main grid line and the auxiliary grid line of the electrode being higher than other areas of the main grid line, thereby solving the technical problem that in the prior art, due to the height of the auxiliary grid line being higher than the main grid line of the electrode of the solar cell, there will be a height difference, and there is an extrusion force during welding, which is likely to cause hidden cracks or fragments. Description of the Drawings

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0022] Figure 1 Shows a main grid line and a sub-grid line structure diagram in an embodiment of the present invention;

[0023] Figure 2 Shows a main grid screen structure diagram in an embodiment of the present invention;

[0024] Figure 3 Shows a sub-grid screen structure diagram in an embodiment of the present invention;

[0025] Figure 4 Shows a main and sub-grid line structure diagram on a printing screen of an electrode of a solar cell in an embodiment of the present invention;

[0026] Figure 5 Shows a flowchart of a printing method for an electrode of a solar cell in an embodiment of the present invention;

[0027] Figure 6 Shows a partial enlarged view of the lap joint between the main grid wire mesh and the emulsion of the main grid screen in an embodiment of the present invention. Detailed implementation manners

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0029] The inventors of the present invention have found through research that the main reasons for easy occurrence of hidden cracks or fragments during subsequent battery interconnection are as follows: at the intersection of the main and sub-grids, the sub-grid overlaps the main grid, so the grid line height at the intersection of the main and sub-grids is higher than that of other areas of the main grid, that is, it is uneven in the extending direction of the main grid; when welding the welding rod, the contact points between the welding rod and the main grid are too few, and the overall welding tension is reduced; and due to the height difference, there is extrusion pressure during welding, which is likely to cause hidden cracks or fragments.

[0030] An embodiment of the present invention discloses an electrode of a solar cell, and the electrode includes a main grid line and a sub-grid line; refer to Figure 1, the secondary grid line 1 intersects with the main grid line; at the intersection, the secondary grid line 1 overlaps on the main grid line 2; the height of the main grid line 2 in the intersection area is less than the height of the other areas of the main grid line 2. Specifically, the height of the secondary grid line 1 at the intersection is n2, the height of the main grid line 2 at the intersection is n1, and the height of the other areas of the main grid line is n3. It can be seen that the height n3 of the other areas of the main grid line is basically equal to the sum of the height n2 of the secondary grid line 1 at the intersection and the height n1 of the main grid line 2 at the intersection. The planar heights of the main grid line and the secondary grid line of the solar cell in the embodiment of the present invention are basically the same, thus perfectly solving the technical problem that in the intersection area of the main grid line and the secondary grid line, due to the height of the secondary grid line being higher than that of the main grid line, there will be a height difference, and the extrusion force during welding is likely to cause hidden cracks or fragments.

[0031] In the embodiment of the present invention, the height of the main grid line in the intersection area is less than the height of the other areas of the main grid line. In this way, the main grid line is thinned in advance in the intersection area. After the secondary grid line overlaps on the main grid line, the height of the area where the main grid line and the secondary grid line intersect can be made basically the same as the height of the other areas, avoiding unevenness, and thus solving the technical problem that the extrusion force during welding is likely to cause hidden cracks or fragments.

[0032] Optionally, the sum of the height of the main grid line and the height of the secondary grid line in the intersection area is equal to the height of the other areas of the main grid line. In this way, further, in the extending direction of the main grid line, the heights of the grid lines are the same, which is more conducive to the welding electrode and further reduces the problems of hidden cracks and fragments.

[0033] Optionally, the height of the secondary grid line in the intersection area is less than the height of the other areas of the secondary grid line.

[0034] In this way, the secondary grid line is also thinned in advance in the intersection area, further making the thinning of the main grid line and the secondary grid line smaller respectively, which is beneficial to the uniformity of the main grid line and the secondary grid line and is beneficial to improving the printing process.

[0035] In the present invention, the height of the main grid line in the intersection area is less than the height of the other areas of the main grid line, which can make the height of the area where the main grid line and the secondary grid line of the electrode intersect basically the same as the height of the other areas of the main grid line or the secondary grid line of the electrode after intersection, avoiding the height of the intersection area of the main grid line and the secondary grid line of the electrode being higher than the other areas of the main grid line, and thus solving the technical problem that in the existing solar cell electrode, due to the height of the secondary grid line being higher than that of the main grid line, there will be a height difference, and the extrusion force during welding is likely to cause hidden cracks or fragments.

[0036] The present invention also discloses a printing screen for the electrode of a solar cell, and the printing screen includes a main grid screen and a secondary grid screen;

[0037] The main grid stencil includes a main grid frame, a main grid wire mesh installed within the main grid frame, and a main grid emulsion layer covering a partial surface of the main grid wire mesh;

[0038] The auxiliary grid stencil includes an auxiliary grid frame, an auxiliary grid wire mesh installed within the auxiliary grid frame, and an auxiliary grid emulsion layer covering a partial surface of the auxiliary grid wire mesh;

[0039] The main grid emulsion layer includes a first region corresponding to the printing area where the main grid intersects with the auxiliary grid and a second region corresponding to other printing areas of the main grid; the thickness of the main grid emulsion layer in the first region is less than the thickness of the main grid emulsion layer in the second region.

[0040] Refer to Figure 2 As shown in the structure of the main grid stencil, the main grid stencil includes a main grid frame 101, a main grid wire mesh 102 installed within the main grid frame 101, and a main grid emulsion layer 103 covering a partial surface of the main grid wire mesh. The main grid emulsion layer 103 includes a first region corresponding to the printing area where the main grid intersects with the auxiliary grid and a second region corresponding to other printing areas of the main grid; the thickness of the main grid emulsion layer in the first region is less than the thickness of the main grid emulsion layer in the second region.

[0041] Among them, the main grid frame is used to fix the main grid wire mesh. The main grid wire mesh can be a steel wire mesh or a wire mesh made of other materials. The embodiments of the present invention do not make specific limitations in this regard.

[0042] Refer to Figure 3 As shown in the structure of the auxiliary grid stencil, the auxiliary grid stencil includes an auxiliary grid frame 201, an auxiliary grid wire mesh 202 installed within the main grid frame 201, and an auxiliary grid emulsion layer 203 covering a partial surface of the auxiliary grid wire mesh.

[0043] Among them, the auxiliary grid frame is used to fix the auxiliary grid wire mesh. The auxiliary grid wire mesh can be a steel wire mesh or a wire mesh made of other materials. The embodiments of the present invention do not make specific limitations in this regard.

[0044] In the embodiments of the present invention, since the thickness of the main grid emulsion layer in the first region is less than the thickness of the main grid emulsion layer in the second region, and the thickness of the emulsion layer in the corresponding region determines the height of the main grid line formed by printing in this region; when using this main grid stencil to print the main grid line on the substrate of the solar cell, the height of the main grid line printed in the first region can be made less than the height of the main grid line printed in other regions. In this way, after the main grid line is printed on the substrate, when using the auxiliary grid stencil to print the auxiliary grid line on this substrate, the height of the region where the main grid line and the auxiliary grid line intersect can be made basically the same as the height of other regions, avoiding the technical problems of easy occurrence of hidden cracks or fragmentation due to extrusion force during welding.

[0045] Optionally, the sub-grid emulsion layer includes a third region corresponding to the printing area where the sub-grid intersects with the main grid and a fourth region corresponding to other printing areas of the sub-grid; the thickness of the sub-grid emulsion layer in the third region is less than the thickness of the sub-grid emulsion layer in the fourth region.

[0046] In an embodiment of the present invention, corresponding to the electrode structure of the solar cell, the sub-grid emulsion layer here is divided into a third region and a fourth region, and the thickness of the sub-grid emulsion layer in the third region is less than the thickness of the sub-grid emulsion layer in the fourth region. When using this stencil to print sub-grid lines on the electrode substrate of the solar cell, the sub-grid lines will also be thinned in advance in the intersection region, further reducing the thinning of the main grid line and the sub-grid line respectively, which is beneficial to the uniformity of the main grid line and the sub-grid line and is beneficial to improving the printing process.

[0047] Optionally, the sum of the emulsion thickness of the first region of the main-grid emulsion layer and the emulsion thickness of the third region of the sub-grid emulsion layer is equal to the emulsion thickness of the second region of the main-grid emulsion layer.

[0048] Refer to Figure 4 , which shows the specific position of the first region, specifically showing the main grid line 10 on the solar cell electrode, the sub-grid line 20 on the solar electrode, and the overlapping region 30 of the main grid line and the sub-grid line. Among them, the overlapping region 30 corresponds to the first region of the main-grid stencil.

[0049] Optionally, the main-grid stencil includes a first positioning point, and the sub-grid stencil includes a second positioning point. The number of the first positioning points is greater than or equal to two, and the number of the second positioning points is greater than or equal to two.

[0050] In an embodiment of the present invention, the first positioning point and the second positioning point play a positioning role when printing the solar cell. In order to achieve a more accurate positioning effect, the number of the first positioning point and the second positioning point is set to be not less than two. As a specific example, refer to Figure 2 and Figure 3 , the number of the first positioning points 104 and the second positioning points 204 is 4, and they are respectively distributed at both ends of the two diagonals of the main-grid area and the sub-grid area.

[0051] Optionally, the width of the main-grid printing area of the main-grid stencil is greater than or equal to 38 microns and less than or equal to 42 microns, and the depth is greater than or equal to 10 microns and less than or equal to 13 microns. The main-grid printing area of the main-grid stencil refers to the area on the main-grid stencil corresponding to the formation of the main grid line, that is, the area where the electrode paste leaks from the mesh holes of the screen; that is, the area without coating the main-grid emulsion layer.

[0052] The width of the sub-grid printing area of the sub-grid stencil is greater than or equal to 27 microns and less than or equal to 29 microns, and the depth is greater than or equal to 11 microns and less than or equal to 15 microns. The sub-grid printing area of the sub-grid stencil refers to the area on the sub-grid stencil corresponding to the formation of the sub-grid lines, that is, the area where the electrode paste leaks from the mesh holes of the screen; that is, the area where the sub-grid emulsion layer is not coated.

[0053] In the embodiment of the present invention, the sizes of the main-grid printing area of the main-grid stencil and the sub-grid printing area of the sub-grid stencil are determined by the actual required sizes on the solar cell electrode. It can be understood that the main-grid printing area of the main-grid stencil and the sub-grid printing area of the sub-grid stencil can also be other sizes, and the embodiment of the present invention does not make specific limitations on this.

[0054] As a specific example, the width of the main-grid printing area is 40 microns and the depth is 12 microns; the width of the sub-grid printing area is 28 microns and the depth is 13 microns.

[0055] As another specific example, the width of the main-grid printing area is 42 microns and the depth is 13 microns; the width of the sub-grid printing area is 29 microns and the depth is 15 microns.

[0056] Optionally, the sub-grid emulsion layer includes an intermediate printing area and an edge area surrounding the intermediate printing area; the intermediate printing area is substantially the same as the shape of the battery cell; the sub-grid printing area is located within the intermediate printing area; the emulsion thickness of the edge area is greater than the emulsion thickness of the intermediate printing area.

[0057] In the embodiment of the present invention, the fact that the emulsion thickness of the edge area of the sub-grid stencil is greater than the emulsion thickness of the intermediate printing area can effectively avoid the problems of paste leakage and deformation at the corners of the stencil during the printing process using the sub-grid stencil.

[0058] In the embodiment of the present invention, the height of the main-grid line in the intersection area is less than the height of the other areas of the main-grid line, which can make the height of the intersection area of the main-grid line and the sub-grid line of the electrode basically the same as the height of the other areas of the main-grid line or the sub-grid line of the electrode after the intersection of the main-grid line and the sub-grid line of the electrode, avoiding the height of the intersection area of the main-grid line and the sub-grid line of the electrode being higher than the other areas of the main-grid line, thereby solving the technical problem that in the existing technology, due to the height of the sub-grid line being higher than the main-grid line of the solar cell electrode, there will be a height difference, and there is an extrusion force during welding, which is likely to cause hidden cracks or fragmentation.

[0059] The embodiment of the present invention also discloses a printing method for the electrode of a solar cell, referring to Figure 5 , including the following steps:

[0060] Step 101, print the main-grid line on the battery cell using the main-grid stencil; then print the sub-grid line using the sub-grid stencil.

[0061] In an embodiment of the present invention, when printing the main grid lines on the substrate of a solar cell using a main grid stencil, the main grid wire mesh in the main grid stencil is arranged on the side far from the substrate of the solar cell, and the paste for preparing the electrode is passed through the main grid wire mesh and based on the main grid stencil to form the main grid lines on the substrate of the solar cell. The main grid lines are convex structures. When printing the sub-grid lines on the substrate of the solar cell using a sub-grid stencil, the sub-grid wire mesh in the sub-grid stencil is arranged on the side far from the substrate of the solar cell, and the paste for preparing the electrode is passed through the sub-grid wire mesh and based on the sub-grid stencil to form the sub-grid lines on the substrate. The sub-grid lines intersect with the main grid lines, and the height of the intersection area between the sub-grid lines and the main grid lines is the same as that of other areas of the main grid lines, thus solving the technical problem that since the height of the sub-grid lines is higher than that of the main grid lines, there will be a height difference, and the extrusion force during welding is likely to cause hidden cracks or fragmentation.

[0062] Optionally, the height of the intersection area between the main grid lines and the sub-grid lines on the electrode of the solar cell is the same as the height of the non-intersection areas between the main grid lines and the sub-grid lines.

[0063] In an embodiment of the present invention, when using the main grid stencil to print on the substrate of the solar cell, the electrode paste passes through the main grid stencil to print the main grid lines on the substrate of the solar cell, and then uses the sub-grid stencil for printing. The electrode paste passes through the sub-grid stencil to print the sub-grid lines on the substrate of the solar cell, and the sub-grid lines penetrate the main grid lines.

[0064] Refer to Figure 6 , the partial enlarged view of the lap joint of the wire mesh and the emulsion. The first area of the main grid stencil can adjust the emulsion thickness of the mark 5 to make the printing height at the intersection consistent with that of the sub-grid, so that effective gain can be obtained at both the solar cell end and the module end. The area of the mark 5 is only a part of the first area and cannot show the complete target area.

[0065] The above steps form the precise intersection of the main grid lines and the sub-grid lines. The height at the intersection of the main grid lines and the sub-grid lines is the same as the height at the non-intersection of the main grid lines and the sub-grid lines, ensuring the welding tensile force at the module end.

[0066] In an embodiment of the present invention, the height of the main grid lines in the intersection area is less than the height of other areas of the main grid lines, which can make the height of the intersection area of the main grid lines and the sub-grid lines of the electrode basically the same as the height of other areas of the main grid lines or the sub-grid lines of the electrode after intersection, avoiding the height of the intersection area of the main grid lines and the sub-grid lines of the electrode being higher than other areas of the main grid lines, thus solving the technical problem that in the existing technology, due to the height of the sub-grid lines being higher than that of the main grid lines in the electrode of the solar cell, there will be a height difference, and the extrusion force during welding is likely to cause hidden cracks or fragmentation.

[0067] It should be noted that in this text, the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising such element.

[0068] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the claims of the present invention, and all of these fall within the protection scope of the present invention.

Claims

1. An electrode of a solar cell, characterized in that, The electrode includes a main gate line and a sub-gate line; the sub-gate line intersects the main gate line; At the intersection, the sub-gate line overlaps the main gate line; The height of the main gate line in the intersection area is less than the height of the main gate line in other areas; The height of the sub-gate line in the intersection area is less than the height of the sub-gate line in other areas.

2. The electrode according to claim 1, wherein The sum of the height of the main gate line and the height of the sub-gate line in the intersection area is equal to the height of the main gate line in other areas.

3. A printing stencil for an electrode of a solar cell, characterized in that, The printing stencil includes a main gate stencil and a sub-gate stencil; The main gate stencil includes a main gate frame, a main gate wire mesh installed in the main gate frame, and a main gate emulsion layer covering a part of the surface of the main gate wire mesh; The sub-gate stencil includes a sub-gate frame, a sub-gate wire mesh installed in the sub-gate frame, and a sub-gate emulsion layer covering a part of the surface of the sub-gate wire mesh; The main gate emulsion layer includes a first area corresponding to the printing area where the main gate and the sub-gate intersect and a second area corresponding to other printing areas of the main gate; The thickness of the main gate emulsion layer in the first area is less than the thickness of the main gate emulsion layer in the second area; The sub-gate emulsion layer includes a third area corresponding to the printing area where the sub-gate and the main gate intersect and a fourth area corresponding to other printing areas of the sub-gate; the thickness of the sub-gate emulsion layer in the third area is less than the thickness of the sub-gate emulsion layer in the fourth area; The main gate stencil includes at least two first positioning points, and the sub-gate stencil includes at least two second positioning points.

4. The printing screen according to claim 3, characterized in that, The sum of the thickness of the main gate emulsion layer in the first area and the thickness of the sub-gate emulsion layer in the corresponding sub-gate printing area is equal to the thickness of the main gate emulsion layer in the second area.

5. The printing screen plate according to any one of claims 3-4, characterized in that, The width of the main gate printing area of the main gate stencil is greater than or equal to 38 microns and less than or equal to 42 microns, and the depth is greater than or equal to 10 microns and less than or equal to 13 microns.

6. The printing screen according to any one of claims 3-4, characterized in that, The width of the sub-gate printing area of the sub-gate stencil is greater than or equal to 27 microns and less than or equal to 29 microns, and the depth is greater than or equal to 11 microns and less than or equal to 15 microns.

7. The printing screen according to claim 3, characterized in that, The sub-gate emulsion layer includes an intermediate printing area and an edge area surrounding the intermediate printing area; the thickness of the sub-gate emulsion layer in the edge area is greater than the thickness of the sub-gate emulsion layer in the intermediate printing area.

8. A printing method for an electrode of a solar cell, characterized in that, Applied to the printing stencil according to any one of claims 3-7, it includes the following steps: Print the main gate line on the battery cell using the main gate stencil; then print the sub-gate line using the sub-gate stencil.

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