WO2011158913A1

WO2011158913A1 - Mesh member for screen printing

Info

Publication number: WO2011158913A1
Application number: PCT/JP2011/063847
Authority: WO
Inventors: 啓吾高岡; 隆古保里
Original assignee: 株式会社コベルコ科研
Priority date: 2010-06-16
Filing date: 2011-06-16
Publication date: 2011-12-22
Also published as: JP5325839B2; KR20130012076A; CN102933397A; CN102933397B; JP2012000845A; KR101420040B1

Abstract

Provided is a mesh member for screen printing, which: uses a high-viscosity paste; achieves printing with little printing width variation and has a high printing height even when the width of the printing pattern is small (narrow); and has the required and even strength. Specifically provided is a mesh member for screen printing and for forming a printing pattern by means of a photosensitive emulsion. The mesh member for screen printing is characterized by being formed by means of a rolled metal foil, wherein the rolled metal foil has: a section corresponding to a printing region in which an object to be printed is printed; and a section corresponding to a non-printing region in which the object to be printed is not printed. The section corresponding to the printing region is arranged, in a row, with a plurality of holes having a shape which expands towards the object to be printed, and is provided with a region in which the lines separating the adjacent holes do not intersect.

Description

Mesh material for screen printing

The present invention relates to a mesh member used for screen printing, and particularly in printing using a high-viscosity paste used for printing a surface electrode of a solar cell, even when the width of a printing pattern is reduced (thinned), the printing height The present invention relates to a mesh member for screen printing for realizing printing that is high and has a small variation in printing width.

Screen printing is used not only for the production of electronic components such as multilayer chip capacitors, but also for the formation of current collecting main electrodes (bus bars) and current collecting grid electrodes (finger electrodes) that are surface electrodes of solar cells. A printing plate (screen plate) used for screen printing uses a mesh member formed by knitting fine lines made of metal or resin (polyester). In addition, a mesh fabric (hereinafter referred to as “polyester mesh fabric”) formed by knitting polyester fine wires around a mesh fabric (hereinafter sometimes referred to as “metal mesh fabric”) formed by knitting stainless steel fine wires. Printing plates (combination masks) formed by bonding (sometimes called) are also widely used.

When creating a combination mask, first, a metal mesh fabric is bonded to a polyester mesh fabric stretched on an aluminum mold, and after drying, the polyester mesh fabric overlapping the metal mesh fabric is cut. Thereafter, a photosensitive emulsion is applied, and a target print pattern is exposed and developed on a metal mesh fabric, thereby producing a combination mask. When mesh fabrics formed by knitting fine wires have the same thickness, the amount of paste to be transmitted increases as the mesh fabric opening ratio (total area ratio of mesh openings 2 shown in FIG. 1) increases. A metal mesh fabric having an aperture ratio of about 50 to 60% is used for printing the surface electrodes of solar cells.

¡In order to reduce the size of electronic components and improve the power generation efficiency of solar cells, efforts are being made to narrow and increase the width of electrodes printed by screen printing. Since the resistance value of the electrode depends on the cross-sectional area, in order to reduce the size of electronic components and increase the light receiving area of the solar cell to increase the power generation efficiency, the cross-sectional area should be made as narrow and high as possible. It is necessary to increase the resistance value of the electrode so as not to increase. However, when printing using a metal mesh fabric, there is a problem that mesh marks are likely to remain, and variations in printing height are likely to vary. In addition, after printing (after the printing squeegee passes), the paste may remain at a portion where the fine lines of the mesh fabric of the printing plate intersect, and the printing (electrode) height may be lowered. Therefore, when the print pattern width is made smaller, print fading is likely to occur, and there may be a portion where the electrode height is low. In such a case, the target electric resistance value cannot be obtained.

FIG. 1 is a partially enlarged explanatory view of a printing plate usually used for screen printing. In FIG. 1, a mesh member (mesh fabric) formed by knitting a thin wire 1 made of metal or polyester and having an opening 2 is stretched on a screen frame (not shown). Thereafter, the photosensitive emulsion (resin) 4 is coated on the entire surface and covered with a mask, and the photosensitive emulsion 4 is cured by exposure only to a portion not to be printed. And the printing plate 5 is produced by removing the photosensitive emulsion 4 of the part to print.

In screen printing, as shown in FIG. 2A, the paste 7 is filled into the opening 2 of the print pattern portion 3 (see FIG. 1) by moving the squeegee 6, and Paste 7 is deposited. After the squeegee 6 passes, the printing plate 5 (see FIG. 1) is separated from the printing object 8 due to the tension of the printing plate, but the paste 7 remains on the printing object 8. Thereafter, three patterns of the print pattern portion from which the photosensitive emulsion 4 has been removed are printed. The paste 7 immediately after printing is thick in the portion corresponding to the opening 2 and thin in the portion corresponding to the thin line 1 (FIG. 2B). Thereafter, the paste 7 is flattened (leveled) due to the viscosity and surface tension of the paste 7 (FIG. 2C). At this time, the paste 7 spreads beyond the opening 2 of the printing plate 5. The spread of the paste is indicated by reference numeral 7a in FIG. 2 (c) and is called printing bleeding.

The printing film thickness (the thickness d1 of the paste 7 applied to the printing object 8) is determined by the thickness of the printing plate 5 and the aperture ratio of the mesh member (total area ratio of the opening 2). It is known that the following relationship holds when the printing area is the same.
Printing film thickness (μm) = printing plate thickness (μm) × opening ratio (%)

If a mesh member with no irregularities on the surface is used, it is difficult to leave mesh marks, and it can be expected that the difference in printing height can be reduced. As a method of manufacturing a mesh member having no irregularities on its surface, a method of depositing nickel or the like in a mesh shape by electroforming has been proposed (for example, Patent Documents 1 and 2). However, it is known that the metal foil produced by the electroforming method has a variation in strength, and the mesh member produced by the electroforming method may have a variation in strength. In addition, it is conceivable to make a mesh member by punching an electrolytic foil of nickel or the like by etching or the like, but there is a risk of variation in strength as in the case of a mesh member by electroforming.

Japanese Patent No. 3516882 Japanese Patent No. 2847746

The present invention has been made in view of such a situation, and the width of the printed pattern is reduced (thinned) by using a high-viscosity paste such as a conductive silver paste used for printing of a surface electrode of a solar cell. In this case, it is an object to provide a mesh member for screen printing that can realize printing with a high printing height and a small variation in printing width, and has a necessary and uniform strength.

The mesh member for screen printing according to the present invention that has solved the above problems is a mesh member for screen printing for forming a printing pattern with a photosensitive emulsion, and the mesh member for screen printing is made of a rolled metal foil. The rolled metal foil has a portion corresponding to a printing area of a printing object and a portion corresponding to a non-printing area of the printing object, and the portion corresponding to the printing area includes a printing object. It has a gist in that a plurality of holes having a shape spreading toward an object are arranged in a line, and a region where the line portions separating the adjacent holes are not intersected is provided.

In the mesh member for screen printing of the present invention, the breaking load when a tensile test was performed at a tensile speed of 10 mm / min on a test piece having a width of 15 mm and a gauge distance of 100 mm cut out from the portion corresponding to the printing region ( The tensile strength in which N) is converted per 1 cm width of the test piece is 20 N / cm or more.

The mesh member for screen printing of the present invention includes a member in which no hole is formed in a portion corresponding to the non-printing area. In the mesh member for screen printing according to the present invention, a large number of holes are formed in a portion corresponding to the non-printing region, and an aperture ratio of the hole in the portion corresponding to the non-printing region corresponds to the printing region. The thing smaller than the aperture ratio of the hole in a part is included.

The mesh member for screen printing of the present invention preferably has a thickness of 5 μm or more and 30 μm or less. In addition, the screen printing mesh member of the present invention is preferably such that at least a part of the boundary contour between the portion corresponding to the printing region and the portion corresponding to the non-printing region is rounded. In the screen printing mesh member of the present invention, it is preferable that at least one side of the line portion is flat.

The rolled metal foil used as the material for the screen printing mesh member of the present invention is not particularly limited, and examples thereof include stainless steel, titanium or titanium alloy, nickel or nickel alloy, copper or copper alloy, and aluminum alloy.

According to the mesh member for screen printing of the present invention, even when a high-viscosity paste is used, it is possible to realize printing with high printing height and small variation in printing width, and having necessary and uniform strength. A mesh member can be realized. The mesh member for screen printing of the present invention is extremely useful for the production of electronic components and the formation of current collecting main electrodes (bus bars) and current collecting grid electrodes (finger electrodes) that are surface electrodes of solar cells.

It is the elements on larger scale of the printing plate normally used for screen printing. (A) (b) (c) is a figure for demonstrating the filling state of the paste in the screen printing by a prior art. It is a figure explaining the condition where presence of the intersection of the line part which comprises a mesh member affects the number of disconnections. 4 is a graph showing the relationship between the number of locations where the line width B shown in FIG. 3 is 50% or more of the printing width A (the line width is 50% or more of the printing width and more than the printing width) and the number of disconnections. It is an enlarged view for demonstrating the opening shape of the hole of the conventional mesh member. It is explanatory drawing which shows an example of the form of the mesh member of this invention. It is explanatory drawing which shows the other example of the form of the mesh member of this invention. It is explanatory drawing which shows the further another example of the form of the mesh member of this invention. It is explanatory drawing which shows the other example of the form of the mesh member of this invention. It is explanatory drawing which shows an example of the form of the mesh member of a comparative product. (A) is explanatory drawing which shows the other example of the form of the mesh member of this invention, (b) is a figure which shows the state which apply | coated the photosensitive emulsion to the mesh member of (a). (A) (b) is explanatory drawing which shows an example of the opening shape of the hole in the mesh member of this invention. (A) (b) (c) (d) is explanatory drawing which shows the various examples of the opening shape of the hole in the mesh member of this invention. It is explanatory drawing which shows the further another example of the form of the mesh member of this invention. (A) (b) (c) is a figure for demonstrating the filling state of the paste in screen printing when the mesh member of this invention is used. It is a reference drawing based on a photograph which shows the shape which expanded a part of mesh member obtained in Example 1. FIG. It is the reference drawing based on a photograph which shows the shape which expanded a part of mesh member obtained in Example 2. FIG.

The present inventors discharged a high-viscosity paste using a mesh member (rolled metal foil mesh member) perforated in a rolled metal foil and a mesh member formed of a mesh fabric knitted with a fine stainless steel wire. The situation was observed. As a result, according to the rolled metal foil mesh member, it was found that the state of discharge of the paste was uniform as compared with the mesh member constituted by the mesh fabric. Further, the paste was observed to remain in the openings of the mesh fabric, but the paste did not remain in the holes (openings) of the rolled metal foil mesh member. As described above, according to the rolled metal foil mesh member, the discharge of the paste is uniform and the paste does not remain in the opening, so that printing with a small height difference can be performed. However, when a rolled metal foil mesh member is used, print fading may occur when the width of the print pattern is narrow.

In order to analyze the cause of the occurrence of such a phenomenon, the present inventors used a stainless steel rolled foil having a thickness of 21 μm (standard SUS304-H, manufactured by Toyo Seiki Co., Ltd.) and a mesh number of 250 or 320 (lines / inch). ), An aperture ratio of 50 to 62% and a bias of 22.5 degrees or 57.5 degrees were drilled to produce a mesh member. Using these mesh members, the present inventors produced printing plates having a print pattern portion width (print pattern width) of 40 μm, 60 μm, 80 μm, and 100 μm, respectively. In the present invention, “bias” means an angle formed by the direction of the line portion 1a (see FIG. 5) of the mesh member and the printing direction (left-right direction in FIG. 14).

The present inventors performed a printing test using these printing plates and the silver paste for solar cells, and measured the number of print fading locations (number of disconnections) per 1 cm of the printing length after printing. As a result of the measurement, when the printed pattern width was 100 μm or 80 μm, disconnection hardly occurred. However, the number of breaks increased as the print pattern width became 60 μm and 40 μm, and the number of breaks became maximum when the print pattern width was 40 μm.
Therefore, the present inventors observed the printing plate with a microscope (manufactured by Keyence Corporation, model VHX-2000), and analyzed factors that affect the number of disconnections. As a result of the analysis, when the intersecting portion of the line portion constituting the mesh member exists in the print pattern portion, 50% or more of the print pattern width (print width) is blocked by the line portion and the length of the blocked portion It has been found that there is a positive correlation between the number of places where the print pattern width is greater than or equal to the print pattern width and the number of places with faint printing (number of disconnections).

FIG. 3 is a diagram for explaining a situation in which the presence of the intersecting portion 9 of the line portion 1a constituting the mesh member affects the number of disconnections. In FIG. 3, A is the print pattern width (print width), B is the width blocked by the line portion 1a, and C is B (width blocked by the line portion 1a: line width) is 50% of A. The lengths of the above portions are shown respectively. FIG. 4 shows the relationship between the number of locations where the line width B is 50% or more of the print width A and the line width B is greater than or equal to the print width A and the number of disconnections (however, the print pattern width is 100 μm). 80 μm was not shown because there was no disconnection).

From these results, we could consider as follows. That is, all the places where the line portion 1a blocks 50% or more of the print pattern width A are places where the line portion 1a of the mesh member intersects (intersection portion 9) exists in the print pattern A. For this reason, if the intersecting portion 9 of the line portion 1a of the mesh member is thin, it is expected that printing without fading can be realized. However, if the intersecting portion 9 of the line portion 1a is significantly reduced, the strength is reduced, and there is a risk of breaking during printing plate preparation or printing. Therefore, the present inventors further studied a method for removing the influence of the intersecting portion 9 of the line portion 1a.

As shown in FIG. 5, the conventional mesh member generally has crossed portions 9 in which line portions 1 a are formed in a lattice state. However, such a mesh member causes the above problems. Therefore, the present inventors set the intersecting portion 9 of the line portion 1a in the region for the printing pattern (the portion corresponding to the printing region of the printing object: hereinafter, sometimes simply referred to as “printing region corresponding portion”). I came up with a mesh member that I don't have.

FIG. 6 is an explanatory view showing an example of the form of the mesh member of the present invention. In the mesh member of the present invention, as shown in FIG. 6, the holes 2 in the printing region are arranged in a line, and the portion where the line portion 1a intersects is eliminated in the portion corresponding to the printing region. A mesh member can be realized. By uniform and good paste discharge, even when the print pattern width is narrowed, the print height is high (no print fading), there is no height difference, and the variation in print width is also reduced. Also, only the portion corresponding to the printing area is punched, and the peripheral portion corresponding to the non-printing area (the portion corresponding to the non-printing area of the printing object) is not perforated, or the portion corresponding to the non-printing area corresponds to the printing area. The strength as a mesh member can be maintained by making a hole with a lower opening ratio than the portion. FIG. 7 shows a plan view of an example of such a mesh member (the holes in the non-printing region equivalent portion 12 are not shown). Further, if the holes 2 are arranged in a line as described above in at least a part of the print region equivalent portion 11, the effect of the present invention can be exhibited. FIG. 8 shows a plan view of an example of a mesh member in which holes are arranged in a line and a crossing portion of line portions is not formed in only a part (right side in the drawing) of the printing region equivalent portion 11 (non-printing region equivalent portion). 12 holes are not shown). In FIG. 8, in the other part (the left side in the figure) of the print region equivalent part 11, the intersection part of the line part is formed. In the present invention, “arranged in a line” means a state in which the holes 2 are arranged in the same direction as shown in FIGS.

In order to confirm the effectiveness of the mesh member of the present invention (that is, the mesh member not having the crossing portion 9 of the wire portion 1a), a rolled stainless steel foil having a thickness of 21 μm (standard SUS304-H manufactured by Toyo Seiki Co., Ltd.) ) To form a rolled metal foil mesh member by etching from one side so that the holes 2 in the printing region are square and aligned. The rolled metal foil mesh member has a line width of 15 μm, an opening width of 85 μm, and a mesh count of 250 (lines / inch). This rolled metal foil mesh member (invention product) of the present invention is shown as a plan view in FIG. 9 (the holes in the non-printing area are not shown).

Further, as a comparative product, a rolled metal foil mesh having a plurality of square holes 2 arranged in a print region (a print region having a wide print pattern width and a print region having a narrow print pattern width) and having intersecting portions 9 of line portions 1a Produced. This comparative rolled metal foil mesh member is shown as a plan view in FIG. 10 (the holes in the non-printing area are not shown).

Incidentally, the bias of the mesh member of the present invention (FIG. 9) having no crossing portion of the line portion is 0 degree, and the bias of the comparative product (FIG. 10) having the crossing portion 9 is 22.5 degree. Using these rolled metal foil mesh members, printing plates having a printing pattern width of 40 μm were prepared, and a printing test was performed using a silver paste for solar cells. Three printed electrodes are observed with a microscope (manufactured by KEYENCE: model VHK-2000), and the number of print blur spots per 1 cm of electrode length (number of disconnections) is measured. The results are shown in Table 1.

From this result, it can be considered as follows. Since the comparative product has the intersecting portion 9 of the line portion 1a in the print pattern, the paste does not sufficiently wrap around the line portion of the mesh member at this portion, and printing blur occurs. On the other hand, since the mesh member of the invention does not have the intersecting portion 9 of the line portion 1a, the paste sufficiently wraps around the lower side of the line portion, and printing blur does not occur.

When the shape (opening shape) of the hole (opening) 2 in the mesh member is a square (FIGS. 6 and 9), the exposure position (that is, the coating position of the photosensitive emulsion) is shifted from the printing area when the print pattern is exposed. There is a risk that the print pattern as designed may not be formed. Further, when the print pattern is shifted from the print area and enters the non-print area, the paste is not ejected. Therefore, the hole 2 preferably has an opening width larger than the print pattern width. FIG. 11A is a plan view of the mesh member, and FIG. 11B is a diagram showing a state in which a photosensitive emulsion is applied to the mesh member of FIG. In the area that does not have the intersection 9 of the line portion 1a corresponding to the print area, if the shape of the hole 2 is rectangular, the strength can be maintained and the print area can be exposed even if the print pattern exposure position is slightly shifted. Emulsion 4 can be applied (FIG. 11b) and a printed pattern can be formed.

In order to avoid stress concentration when the mesh member is stretched on the aluminum frame or when printing pressure is applied by the squeegee during printing, the corner of the hole 2 in the region that does not have the intersection of the line portions in the printing region equivalent portion 11 is used. It is preferable to add an R shape to the. FIG. 12A shows a case where the opening shape of the hole 2 is rectangular, and FIG. 12B shows a case where the hole 2 has an R shape. Further, the opening shape of the hole 2 is not limited to a shape in which squares or rectangles are arranged in parallel. For example, the parallelogram-shaped holes 2 (FIG. 13A) or the trapezoidal holes (FIG. 13C) may be arranged in a line, or the rectangular holes 2 may be inclined and arranged in a line. Alternatively, the rectangular shape may be curved (FIG. 13D), and various shapes can be employed. These shapes may be selected in consideration of the shape and width of the print pattern.

As shown in FIG. 14, the outline of the boundary between the portion of the rolled metal foil corresponding to the print region (print region equivalent portion 11) and the portion of the rolled metal foil corresponding to the non-print region (non-print region equivalent portion). When at least a part is formed to be rounded, the stress concentration at the time of tensioning can be reduced, and a mesh member that is difficult to break can be obtained. In particular, it can be expected that breakage can be prevented even when the mesh member is thin (approximately 20 μm or less), has a high aperture ratio, and is stretched with higher tension.

The boundary D between the print area equivalent part 11 and the non-print area equivalent part 12 is set with reference to the end of the opening 2 of the print area equivalent part 11 as shown in FIGS. Is done. This boundary D becomes a reference when calculating the respective aperture ratios of the printing area equivalent portion 11 and the non-printing area equivalent portion 12.

The mesh member of the present invention is configured from the viewpoint of improving strength while increasing the aperture ratio. The rolled metal foil has a portion corresponding to a non-printing region of the printing object (a portion corresponding to a non-printing region) in addition to a portion corresponding to the printing region of the printing object (a portion corresponding to the printing region). The member includes a form in which no hole is formed in a portion corresponding to the non-printing area (that is, the aperture ratio is 0%). In addition, the mesh member of the present invention has holes in the portion corresponding to the non-printing area, but the opening ratio of the hole in the portion corresponding to the non-printing area is smaller than the hole opening ratio in the portion corresponding to the printing area. Including.

If no hole is formed in the portion corresponding to the non-printing area of the rolled metal foil, the strength is sufficient. However, in such a case, depending on the type of the photosensitive emulsion, the adhesiveness to the rolled metal foil is lowered, and there is a concern that peeling may occur during repeated printing. For this reason, it is preferable to set the aperture ratio of the portion corresponding to the non-printing area in consideration of the adhesiveness of the photosensitive emulsion (and the type of rolled metal foil that affects the adhesiveness).

In addition, the shape of the hole 2 in the thickness direction of the rolled metal foil spreads toward the printing object 8 in order to prevent the paste from staying inside the mesh member and improve the dischargeability of the high-viscosity paste. The shape is preferable (see FIG. 15A). The aperture ratio of the mesh member when the hole 2 is formed in a shape that expands toward the print object 8 is an average value of the aperture ratios on the squeegee surface side and the print object surface side.

If there is a low-strength portion in the mesh member, there is a risk of cracking due to the pressure of the squeegee during printing or printing on the aluminum frame, and the entire mesh may break. The portion of the mesh member with the lowest strength is the portion with the highest aperture ratio. Therefore, with respect to a test piece having a width of 15 mm and a target distance of 100 mm, the tensile speed of 10 mm / The tensile strength obtained by converting the breaking load (N) when the tensile test is performed in minutes per 1 cm width of the test piece is preferably 20 N / cm or more.

A test was conducted to confirm whether the presence or absence of the intersection of the line portions in the printing area affects the tensile strength. A mesh member (invention product) in which only a printing area is perforated in a rolled stainless steel foil of 21 μm thickness (made by Toyo Seiki Co., Ltd., standard SUS304H), and there is no crossing portion of the line portion in the printing region, and the crossing portion is A mesh member (comparative product) was manufactured. The basic shape of each mesh member is the same as in FIGS. Note that the width of each line portion is 50 μm, the opening width is 150 μm, and the number of meshes is 125 (lines / inch). Further, the bias of the mesh member having no intersecting portion of the line portion is 0 degree, and the bias of the mesh member having the intersecting portion is 22.5 degree.

A test piece having a width of 15 mm and a gauge distance of 100 mm is cut out from each mesh member so that the printing area (opening) is in the center, and the tensile speed is 10 mm / min using a tensile tester (Orientec Co., Ltd.). A tensile test was performed. The tensile strength per unit width is obtained by converting the breaking load (N) when the tensile test is performed per 1 cm width of the test piece. The results are shown in Table 2. Thus, it can be seen that even when there is no crossing part of the line part (invention product), it has the same tensile strength as when there is a crossing part of the line part (comparative product).

The higher the aperture ratio of the mesh member, the greater the amount of paste permeation per area. For this reason, in screen printing using a rolled metal foil mesh and a high-viscosity paste, it is desirable that the aperture ratio of the region through which the paste permeates be high. When printing is performed using a paste having a relatively high viscosity among conductive silver pastes, it is desirable that the aperture ratio be 50% or more, ideally 70% or more. However, since increasing the aperture ratio can lead to a decrease in the strength of the mesh member, the aperture ratio when the thickness is 5 μm is up to about 50%, and the aperture ratio when the thickness is 30 μm is up to about 90%. Preferably there is.

Further, when the width of the print pattern is thin, if the number of meshes is small (that is, the pitch of the line portions of the mesh member is large), it is necessary to increase the width of the line portions in order to ensure the required strength. Therefore, when the print pattern width is thin (for example, less than 100 μm), it is preferable to increase the number of meshes, that is, to reduce the pitch of the line portions of the mesh member. From this viewpoint, the number of meshes is preferably 125 (lines / inch) or more. However, if the number of meshes becomes too large, the opening width becomes small and it becomes difficult for a high-viscosity paste to permeate (discharge), so the number of meshes is preferably 420 (lines / inch) or less. When using a paste having a narrower print pattern width (for example, less than 60 μm) and a high viscosity, the number of meshes is preferably 210 (lines / inch) or more and 320 (lines / inch) or less.

When using the same emulsion thickness, the thicker the mesh member, the thicker the print can be made. However, depending on the paste used for printing, if the thickness of the mesh member is too thick, a difference in printing height tends to occur. When such a situation is expected, the thickness of the mesh member (that is, the thickness of the rolled metal foil) is preferably 30 μm or less in order to reduce the height difference. As the mesh member is thinner, printing with less height difference is possible, but a rolled metal foil having a thickness of less than 5 μm is difficult to obtain and it is difficult to ensure strength. Therefore, the thickness of the mesh member is preferably 5 μm or more. From the viewpoint of securing strength, this thickness is more preferably 10 μm or more.

The mesh member of the present invention is manufactured by forming a large number of holes as described above in a rolled metal foil. In such a mesh member, at least one surface constituting the line portion is flat. For example, as shown in FIG. 15A, the movement of the squeegee 6 is smaller than that of a mesh knitted with fine lines having irregularities on the surface. Since it becomes smooth, it is preferable. Further, according to such a mesh member, the paste 7 can be easily stretched uniformly as shown in FIG. 15B, and a relatively thick printed film thickness d2 as shown in FIG. 15C. A pattern can be printed. In addition, when a combination mask (a mask with a resin mesh around and a metal mesh at the center) is produced, if the metal mesh has such a flat surface, it is easy to adhere to the resin mesh. There is also. FIG. 15A also shows a state in which the holes 2 are formed so as to expand toward the printing surface side (printing object 8 side).

The mesh member of the present invention can be manufactured by punching a rolled metal foil by etching, laser processing, or shot blasting, but the etching method is optimal from the viewpoint of opening accuracy and opening speed. In addition, when drilling is performed by etching, if the holes are formed by etching from both sides, there is a possibility that the paste may remain during screen printing due to the convex portions formed in a part of the holes. Therefore, drilling by etching from one surface is good. As a result, the shape (external shape) of the hole 2 is a shape that spreads from one side in the thickness direction of the rolled metal foil toward the other side. Thus, the situation where a paste stays can be avoided by forming the hole of the shape which spreads toward the printing object.

The procedure for producing the mesh member of the present invention by forming a large number of holes in the rolled metal foil by punching by etching is as follows. First, a state in which a rolled metal foil is stretched and attached to a fixed plate having a flat surface such as glass or a roll in which a rolled metal foil is wound, that is, the rolled metal foil is stretched so as not to be wrinkled. In this state, the photosensitive resist is applied as thinly as possible to the rolled metal foil. Then, the pattern of the opening part is formed in the rolled metal foil by exposing and developing the pattern of the opening part of the mesh drawn on the mask.

The procedure for manufacturing a mesh member having a portion corresponding to a non-printing area in which a large number of holes are formed and having a hole opening ratio in the non-printing area corresponding portion smaller than the hole opening ratio in the printing area corresponding portion is as follows. is there. First, after applying a photosensitive resist to the rolled metal foil, a mask on which an opening pattern corresponding to a non-printing area is drawn is placed on a mask on which an opening pattern corresponding to a printing area is drawn. Then, by performing exposure and development, and subsequent etching, a mesh member having a portion with a high aperture ratio and a portion with a low aperture ratio can be manufactured by a relatively simple procedure.

When the print area is set according to the print pattern to be exposed and perforated, and the mesh member is stretched on the aluminum frame, the mesh member may be stretched and the position of the print area may be shifted from the print pattern. Therefore, when the print pattern is exposed, the exposed print pattern may be out of the print area. In that case, a part of the printing pattern enters the non-printing area and the paste is not ejected, so that printing blur and variation in printing width occur. Therefore, if the position of the printing area to be punched is biased to the center in advance, the mesh member is stretched when stretched on the aluminum frame, so that the position of the printing pattern can be easily adjusted.

A test was conducted to confirm the effectiveness of the above configuration. From one side so that the outermost side of the printing area is scaled 0.9992 (100 μm inside) with respect to the printed pattern on a stainless steel rolled foil of 21 μm thickness (Toyo Seiki Co., Ltd., Standard SUS304-H) The rolled metal foil mesh of the present invention was produced by punching by etching. The printed area with a high aperture ratio has a shape that matches the shape of the surface electrode pattern of the solar cell, and the portion where the printed pattern of the finger electrode is exposed and developed has a width of 500 μm. A printing plate was prepared using this mesh member. For comparison, a mesh member was produced that was perforated without any reduction while maintaining the print pattern. With respect to these mesh members, the magnitude of the positional deviation of the printing pattern from the center of the printing area was measured with a microscope (manufactured by Keyence Corporation, model VHX-2000). Table 3 shows the results. Thereby, according to the mesh member of this invention, it has confirmed that there was little position shift.

The material of the rolled metal foil may be any material that can be formed into a foil shape other than stainless steel, such as titanium or titanium alloy, nickel or nickel alloy, copper or copper alloy, or aluminum alloy. For example, SUS304-H or the like for stainless steel, JIS4600 80 or the like for titanium alloy, JISCS2520 (1986) NCHRW1 or the like for nickel alloy, JISH3130 C1720R-H or the like for copper alloy, JISH4000 for aluminum alloy, etc. 5052 or the like. Moreover, such a rolled metal foil is generally commercially available and can be easily obtained.

Hereinafter, the present invention will be described in more detail with reference to examples. The following examples are not intended to limit the present invention, and can be implemented with appropriate modifications within a range that can be adapted to the gist of the preceding and following descriptions, all of which fall within the technical scope of the present invention. included.

[Example 1]
A commercially available rolled stainless steel foil having a thickness of 21 μm (manufactured by Toyo Seiki Co., Ltd .: Standard SUS304H) was punched by etching from one side to produce a rolled metal foil mesh. The region with a high aperture ratio has a shape that matches the shape of the surface electrode pattern of the solar cell. The portion where the printed pattern of the finger electrode is exposed and developed has a width of 500 μm and a length of 152 mm. A portion where the bus bar pattern is exposed and developed has a width of 2.4 mm and a length of 152 mm. Moreover, the hole is formed in a shape in which the opening widens toward the printing surface side. The pitch on the printing surface side of the portion with a high aperture ratio (portion corresponding to the printing region) is 80 μm, and the number of meshes is 320 (lines / inch). Of the portion with a high aperture ratio (the portion corresponding to the printing area), the aperture ratio of the portion that exposes and develops the finger electrode print pattern is 78%, and the aperture ratio of the portion that exposes and develops the bus bar pattern is 52%. The aperture ratio of a portion with a low aperture ratio (corresponding to a non-printing area) is 20%. Among these, the portion where the printed pattern of the finger electrode is exposed and developed does not have a portion where the line portion intersects, and the other portion includes a portion where the line portion intersects. The opening shape of the hole having a high opening ratio has an R shape at the corner. A shape obtained by enlarging a part of the obtained mesh member is shown in FIG.

This mesh member was joined to a polyester fine wire mesh, and after applying a photosensitive emulsion, a printing pattern having a finger electrode width of 40 μm and a bus bar width of 2 mm was exposed and developed to prepare a printing plate. Using the prepared printing plate, printing using conductive silver paste (Toyo Ink Manufacturing Co., Ltd .: “RAFS”) is performed, and the printing height is measured with a laser microscope (Keyence Co., Ltd .: Model VK-9700). did. As a result, it was confirmed that there was no fading and printing was possible with an average height of 18 μm, height difference of 9 μm, and width variation of 4 μm.

In addition, from the obtained mesh member, the portion where the printed pattern of the finger electrode having the highest aperture ratio in the portion corresponding to the printing area is exposed and developed (the portion where the holes are arranged in a line) becomes the central portion of the gauge distance. A test piece having a width of 15 mm and a gauge distance of 100 mm was cut out. The tensile strength obtained by converting the breaking load (N) when the tensile test was performed at a tensile speed of 10 mm / min to the test piece per cm of the width of the test piece was 29 N / cm.

[Example 2]
A commercially available rolled stainless steel foil having a thickness of 21 μm (manufactured by Toyo Seiki Co., Ltd .: Standard SUS304H) was punched by etching from one side to produce a rolled metal foil mesh. The area with a high aperture ratio is a shape that matches the shape of the surface electrode pattern of the solar cell, and the dimensions of the portion where the finger electrode print pattern is exposed and developed are 400 μm wide, 152 mm long, and the bus bar pattern is exposed and developed. The dimensions of the part to be developed are 2.4 mm in width and 152 mm in length. Moreover, the external shape of the hole is a shape in which the opening widens toward the printing surface side. The pitch on the printing surface side of the portion with a high aperture ratio (portion corresponding to the printing region) is 100 μm, and the number of meshes is 250 (lines / inch). Of the portion with a high aperture ratio (corresponding to the printing area), the aperture ratio of the portion that exposes and develops the finger electrode print pattern is 64%, and the aperture ratio of the portion that exposes and develops the bus bar pattern is 51%. The aperture ratio of a portion with a low aperture ratio (corresponding to a non-printing area) is 20%. Among these, there are no portions where the line portions intersect at the portions where the printed pattern of the finger electrode is exposed and developed, and there are portions where the line portions intersect at other portions. The opening shape of the hole having a high opening ratio has an R shape at the corner. A shape obtained by enlarging a part of the obtained mesh member is shown in FIG. 17 (drawing substitute micrograph).

This mesh member was joined to a polyester fine wire mesh, and after applying a photosensitive emulsion, a printing pattern having a finger electrode width of 60 μm and a bus bar width of 2 mm was exposed and developed to prepare a printing plate. Using the obtained printing plate, printing using a conductive silver paste (Toyo Ink Manufacturing Co., Ltd .: “RAFS”) was performed, and the printing height was measured with a laser microscope (Keyence Co., Ltd .: Model VK-9700). did. As a result, it was confirmed that printing could be performed with no fading, an average height of 26 μm, a height difference of 6 μm, and a width variation of 5 μm.

In addition, from the portion corresponding to the print area of the obtained mesh member, the portion that exposes / develops the print pattern of the finger electrode with the highest aperture ratio among the portions corresponding to the print region (portion in which the holes are arranged in a line) is the mark distance A test piece having a width of 15 mm and a gauge distance of 100 mm was cut out so as to be the central part of the test piece. A tensile test was performed on the test piece at a tensile speed of 10 mm / min. The tensile strength at which the breaking load (N) at this time was converted per 1 cm width of the test piece was 43 N / cm.

The embodiments and examples of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. Is. This application is based on a Japanese patent application filed on June 16, 2010 (Japanese Patent Application No. 2010-137720), the contents of which are incorporated herein by reference.

1 Thin wire 1a Wire part 2 Hole (opening)
3 Print Pattern 4 Photosensitive Emulsion 5 Printing Plate 6 Squeegee 7 Paste 7a Bleeding 8 Print Object 9 Intersection

Claims

A screen printing mesh member for forming a printing pattern with a photosensitive emulsion,
The screen printing mesh member is formed of a rolled metal foil,
The rolled metal foil has a portion corresponding to a printing area of a printing object and a portion corresponding to a non-printing area of the printing object,
In the portion corresponding to the printing region, a plurality of holes having a shape that spreads toward the printing object is arranged in a line, and a region in which the line portions that separate the adjacent holes do not intersect is provided. A mesh member for screen printing characterized by the above.
The breaking load (N) when a tensile test was performed at a tensile speed of 10 mm / min on a test piece having a width of 15 mm and a gauge distance of 100 mm cut out from a portion corresponding to the printing region was expressed as follows. The mesh member according to claim 1, wherein the tensile strength converted to the per unit is 20 N / cm or more.
The mesh member according to claim 1 or 2, wherein no hole is formed in a portion corresponding to the non-printing area.
2. A plurality of holes are formed in a portion corresponding to the non-printing area, and an opening ratio of a hole in a part corresponding to the non-printing area is smaller than an opening ratio of the hole in a part corresponding to the printing area. Or the mesh member of 2.
The mesh member according to any one of claims 1 to 4, wherein the thickness is 5 µm or more and 30 µm or less.
The mesh member according to any one of claims 1 to 5, wherein at least a part of a contour of a boundary between the portion corresponding to the printing region and the portion corresponding to the non-printing region is rounded.
The mesh member according to any one of claims 1 to 6, wherein at least one side of the line portion is flat.
The mesh member according to any one of claims 1 to 7, wherein the rolled metal foil is made of any one of stainless steel, titanium or a titanium alloy, nickel or a nickel alloy, copper or a copper alloy, and an aluminum alloy.