JP6141456B2 - Solar cell manufacturing method and printing mask - Google Patents

Description

  The present invention relates to a method for manufacturing a solar cell, a printing mask, a solar cell, and a solar cell module.

  Currently, solar cells that constitute solar cell modules are mainly provided with electrodes on each of a front surface that is a light receiving surface of a substrate material such as silicon and a back surface on the opposite side. In recent years, solar cells in which electrodes are formed only on the back surface of both surfaces have been put into practical use, but solar cells in which electrodes are formed on both surfaces are still widely used.

  For example, Patent Document 1 adopts the following procedure when manufacturing a solar cell. First, a reflection structure of sunlight on the surface of a substrate material such as silicon is changed, and a texture structure (unevenness) for taking the reflected light into the substrate is formed by a technique such as etching. Next, a pn bond is formed by a technique such as diffusion. Next, an antireflection film for reducing the reflection of sunlight by a light interference effect is formed on at least one surface of the substrate material using a silicon nitride film or the like. Next, a metal paste is applied in a desired pattern on the antireflection film. Next, in order to heat the metal paste and melt the antireflection film with the glass contained in the metal paste to obtain an electrical connection with the substrate, firing is performed to form an electrode. Further, the substrate material is immersed in an etching solution having a property of dissolving the glass component to dissolve the glass component contained in the electrode, thereby reducing the electrical resistance of the electrode.

  For example, Patent Document 2 and Patent Document 3 disclose a method for manufacturing a solar cell having electrodes on both the front surface side and the back surface side of a substrate material.

  In general, a simple method such as screen printing is employed as a method of forming a solar cell electrode. A printing mask used for screen printing is a material to be printed by fixing a base material called a screen mesh made of metal thread or chemical fiber to a mask frame, and fixing the part other than the part that allows metal paste to pass through with resin. Used for patterning.

  In order to reduce the cost of the solar cell module, it is extremely difficult to realize the cost reduction of the constituent material of the solar cell that occupies a large proportion in price. For example, it is necessary to review everything from the substrate material, which is a base material, to the materials and consumables used in each process. Among them, a metal paste material used as an electrode material is usually made of silver as a conductive metal, but it is very expensive. However, simply reducing the amount of electrode material used increases the resistance loss at the electrode and reduces the power generation efficiency of the solar cell. Therefore, it is required to reduce the amount of metal paste used without reducing the power generation efficiency of the solar cell.

  In the grid electrode for collecting the current on the surface side of the solar cell, since the portion where the grid electrode is arranged does not generate power, the grid electrode width is preferably narrow. However, since the electrical resistance increases and the resistance loss increases only by reducing the electrode width, it is desirable that the grid electrode is thicker. As the thickness of the grid electrode is increased, the resistance loss is reduced and the power generation efficiency of the solar cell is improved.

  When a conventional screen printing mask is used, the thickness of the electrode is determined by mask specifications such as the screen mesh wire diameter and opening width. In the printing mask, the specification is expressed using the number of yarns per inch (25.4 mm) used for the screen mesh (hereinafter referred to as mesh count) and the wire diameter of the yarns. For example, 200 yarns per inch and a yarn having a wire diameter of 40 μm are expressed as “200φ40”. Therefore, the larger the number, the finer the mesh, and the relatively smaller the wire diameter.

  In a conventional printing mask, the screen mesh is affixed to the mask frame so that the warp or weft of the screen mesh is inclined 20 to 30 degrees with respect to the grid electrode pattern. This is because when the grid electrode pattern and the yarn are parallel, the pattern edge is covered with the yarn, so that a precise electrode pattern cannot be formed.

  In the solar cell module, the bus electrode of the solar cell is soldered to the back bus electrode of the adjacent solar cell with a soldered copper wire and connected in series. In the present specification, the bus electrode refers to a bus electrode on the surface side. The electrode on the back side bus is described as the back bus electrode.

  In a bus electrode for soldering and connecting solar cells with a soldered copper wire, bonding strength by soldering is required, so there is a limit to reducing the bus electrode width. Therefore, in order to reduce the amount of metal paste used in the bus electrode, it is necessary to reduce the thickness of the bus electrode.

Japanese Patent No. 4486622 Japanese Patent No. 4319006 Japanese Patent No. 4481869

  However, since the bus electrode thickness is determined by mask specifications such as the screen mesh wire diameter and opening width as in the case of the grid electrode, if the grid electrode thickness is increased in order to improve power generation efficiency, the bus electrode thickness is increased. It will also be thicker. In the bus electrode, since the collected current flows on the soldered copper wire soldered on the bus electrode, increasing the thickness of the bus electrode does not reduce the resistance loss and does not improve the power generation efficiency. .

  That is, when the grid electrode is increased in thickness for improving the power generation efficiency of the solar cell, the bus electrode is also increased in thickness, which increases the amount of metal paste used. On the other hand, if the thickness of the bus electrode is reduced in order to reduce the amount of metal paste used, the thickness of the grid electrode is also reduced, and the power generation efficiency of the solar cell is greatly reduced.

  The present invention has been made in view of the above, and is manufactured by a solar cell manufacturing method capable of manufacturing a solar cell having high power generation efficiency at low cost, a printing mask used in the manufacturing method, and a manufacturing method thereof. It aims at obtaining a solar cell and a solar cell module provided with an electrode.

In order to solve the above-described problems and achieve the object, a method for manufacturing a solar cell according to the present invention includes a printing mask having an opening corresponding to an electrode shape having a bus electrode portion and a grid electrode portion. A method of manufacturing a solar cell including a screen printing step in which a paste containing a conductive material as an electrode material is applied to an electrode forming surface of a substrate, wherein the two constituent yarns made of a metal material are twisted. A step of applying the paste using the printing mask provided on the opening with a screen mesh formed using at least one of warp and weft yarns. And

  According to the present invention, it is possible to produce a solar cell having high power generation efficiency at low cost.

FIG. 1 is a diagram illustrating a light receiving surface of a solar battery cell including an electrode formed by the method for manufacturing a solar battery according to the first embodiment of the present invention. FIG. 2 is a diagram showing a back surface opposite to the light receiving surface of the solar battery cell shown in FIG. 1. FIG. 3 is a cross-sectional view of the main part of the solar battery cell according to the first embodiment of the present invention, and is a cross-sectional view taken along line AA in FIGS. 1 and 2. FIG. 4 is a schematic cross-sectional view of a stage portion of a printer used in a screen printing process for forming electrodes. FIG. 5 is an enlarged explanatory view of a main part of FIG. FIG. 6 is a plan view showing an example of a substrate material for forming an electrode in the first embodiment of the present invention. FIG. 7 is a plan view showing an example of a substrate material for forming an electrode in the first embodiment of the present invention. FIG. 8 is a top view showing a print mask used in the screen printing process. 9 is an enlarged cross-sectional view of the BB portion (grid electrode corresponding portion) in FIG. FIG. 10 is an enlarged cross-sectional view of the CC portion (bus electrode corresponding portion) in FIG. FIG. 11 is a schematic diagram of a mask (blank) before forming an electrode pattern in the print mask used in the method for manufacturing the solar cell according to the first embodiment of the present invention. FIG. 12 is an enlarged view of the square part DEFG of FIG. FIG. 13 is a schematic diagram showing the printed surface side after the electrode pattern is formed with the photosensitive emulsion in the printing mask used in the method for manufacturing the solar cell according to the first embodiment of the present invention. FIG. 14 is an enlarged view of the square part DEFG of FIG. FIG. 15 is an enlarged schematic view showing a part of a screen mesh in a general standard printing mask. FIG. 16 is an enlarged schematic view of a part of the screen mesh of the printing mask according to the first embodiment of the present invention. FIG. 17 is a table showing a list of calculation examples of the transmission thickness at the grid electrode openings of a general standard printing mask. FIG. 18 is a chart showing a list of calculation examples of transmission thicknesses in the grid electrode openings of the printing mask according to the first embodiment of the present invention. FIG. 19 is a table showing a list of relative paste usage ratios of the screen mesh of the printing mask according to the first embodiment with respect to the screen mesh of a general standard printing mask. FIG. 20 is a schematic cross-sectional view illustrating the procedure of the method for manufacturing the solar cell module according to the second embodiment of the present invention. FIG. 21: is a cross-sectional schematic diagram explaining the procedure of the manufacturing method of the solar cell module concerning Embodiment 2 of this invention.

  EMBODIMENT OF THE INVENTION Below, embodiment of the manufacturing method of a solar cell concerning this invention, a printing mask, a solar cell, and a solar cell module is described in detail based on drawing. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably. In the drawings shown below, the scale of each member may be different from the actual scale for easy understanding. The same applies between the drawings. Further, even a plan view may be hatched to make the drawing easy to see.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a light receiving surface of a solar battery cell 1 including electrodes formed by the method for manufacturing a solar battery according to the first embodiment of the present invention. FIG. 2 is a diagram showing a back surface opposite to the light receiving surface of the solar battery cell 1 shown in FIG. 1.

  The light receiving surface of the solar battery cell 1 is provided with a light receiving surface side electrode including a grid electrode 21 and a front bus electrode 22 arranged so as to be orthogonal to each other. In FIG. 1, the horizontal direction indicated by the arrow X is the longitudinal direction of the grid electrode 21, and the vertical direction indicated by the arrow Y is the longitudinal direction of the front bus electrode 22.

  A back aluminum electrode 23 and a back bus electrode 24 made of aluminum are provided on the back surface of the solar battery cell 1. In FIG. 2, the vertical direction indicated by the arrow Y that is the same as the longitudinal direction of the front bus electrode 22 is the longitudinal direction of the front bus electrode 22.

FIG. 3 is a cross-sectional view of main parts of the solar battery cell 1 according to the first embodiment of the present invention, and is a cross-sectional view taken along line AA in FIGS. 1 and 2. In the figure, the upper side is a light receiving surface (surface). In the solar battery cell 1, an n-type impurity diffusion layer 32 is formed on the upper surface of a p-type silicon substrate 31 by phosphorus diffusion to form a photoelectric conversion unit having a pn junction. An antireflection film 33 is formed on the upper side of the n-type impurity diffusion layer 32. A front bus electrode 22 is provided on the upper side of the antireflection film 33. The antireflection film 33 under the front bus electrode 22 is melted by firing, and the front bus electrode 22 is in electrical contact with the n-type impurity diffusion layer 32. A back aluminum electrode 23 and a back bus electrode 24 are provided on the back side of the p-type silicon substrate 31. Incidentally, FIG. 3, since shows a cross section along the longitudinal direction of the grid electrode 21 definitive in the region between the adjacent grid electrode 21, the grid electrode 21 is not shown.

  Next, the process for manufacturing the photovoltaic cell 1 shown in FIGS. 1 to 3 will be described. In addition, since the process demonstrated here is the same as the manufacturing process of the general photovoltaic cell using a silicon substrate, it does not show in particular in figure.

First, the p-type silicon substrate 31 is put into a thermal oxidation furnace and heated in the presence of phosphorus oxychloride (POCl ₃ ) vapor. As a result, phosphorus glass is formed on the surface of the p-type silicon substrate 31, phosphorus is diffused into the p-type silicon substrate 31, and an n-type impurity diffusion layer 32 is formed on the surface layer of the p-type silicon substrate 31.

  Next, after removing the phosphor glass layer of the silicon substrate in a hydrofluoric acid solution, a silicon nitride film (SiN film) is formed on the n-type impurity diffusion layer 32 as the antireflection film 33 by, for example, plasma CVD. The film thickness and refractive index of the antireflection film 33 are set to values that most suppress light reflection. Note that two or more layers having different refractive indexes may be stacked. The antireflection film 33 may be formed by a different film forming method such as a sputtering method.

  Next, a metal paste mixed with silver is printed on the light-receiving surface of the silicon substrate in a comb shape by screen printing, and a metal paste mixed with aluminum is printed on the entire back surface of the silicon substrate by screen printing, followed by baking treatment. It implements and forms a light-receiving surface side electrode and a back surface electrode. On the light receiving surface of the silicon substrate, the antireflection film 33 under the light receiving surface side electrode is melted by baking, and the light receiving surface side electrode is in electrical contact with the n-type impurity diffusion layer 32. As described above, the solar cell shown in FIGS. 1 to 3 is manufactured.

  Next, the electrode formation method in the manufacturing method of the photovoltaic cell concerning this Embodiment is demonstrated. FIG. 4 is a schematic cross-sectional view of a stage portion of a printer used in a screen printing process for forming electrodes. In the screen printing process, the metal paste 5 is applied to the electrode forming surface of the substrate material 3 through the printing mask 2. FIG. 5 is an enlarged explanatory view of a main part of FIG.

  The printing machine shown in FIGS. 4 and 5 includes a stage 4 on which the substrate material 3 is placed, and the stage 4 includes a suction mechanism 7 for fixing the substrate material 3. The suction mechanism 7 fixes the substrate material 3 to the stage 4 by sucking air at the stage 4.

  The printing mask 2 includes a mask frame 6, a screen mesh 9 having warp yarns 11 and weft yarns 12 attached to the printing surface side of the mask frame 6, and a photosensitive emulsion 10. FIG. 5 is drawn with the stage 4 and the mask frame 6 omitted.

  6 and 7 are plan views showing examples of substrate materials for forming electrodes in the first embodiment. As the substrate material 3, for example, a square-shaped substrate as shown in FIG. 6 and a rounded-rectangular substrate having four corners in an arc as shown in FIG. 7 are used. The width M of one side in the square shape shown in FIG. 6 and the width M ′ corresponding to one side in the rounded square shape shown in FIG. 7 are, for example, 156 mm.

  As the substrate material 3, for example, a silicon wafer that is thin plate silicon is used. In the process for manufacturing the solar cell 1 described above, for example, a silicon substrate on which the antireflection film 33 is formed is used. The substrate material 3 may be made of any material as long as an electrode can be formed by a screen printing process.

  The metal paste 5 includes a conductive material that is an electrode material, and the components are adjusted so as to maintain a desired viscosity. Typical conductive materials used for the metal paste 5 include gold, silver, copper, platinum and palladium. The metal paste 5 contains one or more of these conductive materials.

  The printing machine applies the metal paste 5 to the electrode formation surface of the substrate material 3 through the print mask 2 by scanning the squeegee 8 on the print mask 2 on which the metal paste 5 is placed. In the printing mask 2, the metal paste 5 is not passed through the portion covered with the photosensitive emulsion 10, but the metal paste 5 is passed through the portion where the screen mesh 9 is exposed. The pattern is transferred onto the electrode forming surface.

  The metal paste 5 applied to the substrate material 3 by screen printing becomes an electrode by a process generally called baking. In the firing step, heat treatment is performed in the firing furnace so that the peak temperature is 900 ° C. or less, preferably 750 to 800 ° C. The heat treatment time in the firing furnace is generally within 2 minutes.

  When the separation of the p-type electrode and the n-type electrode (hereinafter referred to as pn separation) is performed prior to the formation of the electrode by screen printing, in order to suppress the occurrence of leakage current due to adhesion of the electrode material, the substrate material It is necessary to suppress the adhesion of the metal paste 5 to the outer peripheral side surface 13 and to provide a margin 14 as shown in FIG. For this purpose, it is desirable to form a pattern so that the peripheral portion of the printing mask 2 is covered with the photosensitive emulsion 10. Further, also in the case of performing pn separation by laser processing or the like after electrode formation, in order to suppress the generation of leakage current, the adhesion of the metal paste 5 to the outer edge side surface 13 of the substrate material 3 is suppressed, and the margin 14 is provided. It is desirable.

  The solar cell electrode is formed by the process as described above. In addition, except for the formation method of the electrode for solar cells, a photovoltaic cell is manufactured by the general manufacturing method as described above.

  Next, the printing mask 2 used for electrode formation of the light-receiving surface side electrode of the photovoltaic cell 1 according to the first embodiment will be described in detail. FIG. 8 is a top view showing the printing mask 2 used in the screen printing process. 9 is an enlarged cross-sectional view of the BB portion (grid electrode corresponding portion) in FIG. FIG. 9 is a cross-sectional view at an angle parallel to the weft 12. The left-right direction indicated by the arrow X in FIG. 8 corresponds to the longitudinal direction of the grid electrode 21. The vertical direction indicated by the arrow Y in FIG. 8 corresponds to the longitudinal direction of the front bus electrode 22. The screen mesh 9 has warp yarns 11, weft yarns 12 and photosensitive emulsion 10. As shown in FIG. 9, the photosensitive emulsion 10 is provided with a grid electrode opening 41 as a part of the opening 20 which is a portion where the screen mesh 9 is exposed.

  FIG. 10 is an enlarged cross-sectional view of the CC portion (bus electrode corresponding portion) in FIG. FIG. 10 is a cross-sectional view at an angle parallel to the weft 12. As shown in FIG. 10, the photosensitive emulsion 10 is provided with a bus electrode opening 42 as a part of the opening 20. In the printing mask 2 according to the first embodiment, a screen mesh 9 for holding the metal paste 5 is a general screen mesh using twisted yarns in which two constituent yarns are twisted and knitted as warp and weft yarns. It is characterized by having made a net by the same plain weave. 9 and 10, the twisted yarn is simplified and drawn as a single line.

  FIG. 11 is a schematic diagram of a mask (blank) before forming an electrode pattern in the printing mask 2 used in the method for manufacturing the solar cell according to the first embodiment. FIG. 12 is an enlarged view of the square part DEFG of FIG. The square part DEFG in FIG. 11 corresponds to the outer peripheral corner part DEFG in FIG. The vertical direction indicated by the arrow X in FIG. 11 is the direction that is the longitudinal direction of the grid electrode 21. In FIG. 11, the horizontal direction indicated by the arrow Y is the direction that is the longitudinal direction of the front bus electrode 22. FIG. 11 is a layout view in which FIG. 8 is rotated 90 degrees clockwise. The mask (blank) is composed of the screen mesh 9 and the mask frame 6. A screen mesh 9 is attached to the printing surface side of the mask frame 6.

  FIG. 12 is also a plan view showing a method for making the screen mesh 9. The screen mesh 9 has warp threads 111 to 113 and weft threads 121 to 123. In the drawing, in order to clarify the warp and the weft, only the warp is hatched.

  In the screen mesh 9 according to the first embodiment, warps and wefts are netted so that the top and bottom are alternately switched. In other words, the weft 121 is netted so as to pass under the warp 111, above the warp 112, and below the warp 113. The weft yarn 122 is netted so as to pass over the warp yarn 111, under the warp yarn 112, and over the warp yarn 113. The weft 123 is netted so as to pass under the warp 111, above the warp 112, and below the warp 113.

  Here, in the screen mesh 9 of the first embodiment, the warp and the weft are not made of one each, but the net is made by using a twisted yarn in which two constituent yarns are knitted in advance as the warp and the weft. The The two constituent yarns are tightly knitted so as not to leave a gap as much as possible so that the metal paste 5 does not pass between the two constituent yarns. In the printing mask 2 according to the first embodiment, the screen mesh 9 has a standard configuration except that a twisted yarn obtained by twisting two constituent yarns is used for the warp and the weft. The configuration of the screen mesh of the printing mask is the same.

  FIG. 13 is a schematic diagram showing the printed surface side after the electrode pattern (opening) is formed by the photosensitive emulsion 10 in the printing mask 2 used in the method for manufacturing the solar cell according to the first embodiment. FIG. 14 is an enlarged view of the square part DEFG of FIG. The square part DEFG in FIG. 13 corresponds to the outer corner part DEFG in FIG. Further, the square portion DEFG in FIG. 13 corresponds to the outer peripheral corner portion DEFG in FIG. 11, and the square portion DEFG in FIG. 14 corresponds to the outer peripheral corner portion DEFG in FIG. The vertical direction indicated by the arrow X in FIG. 13 is the direction that is the longitudinal direction of the grid electrode 21. In FIG. 13, the left-right direction indicated by the arrow Y is the direction in which the front bus electrode 22 is longitudinal.

  As shown in FIGS. 13 and 14, the printing mask 2 is obtained by coating and forming the pattern of the photosensitive emulsion 10 on the screen mesh 9, and the photosensitive emulsion covering the screen mesh 9 and a part of the screen mesh 9. 10 and a mask frame 6. The photosensitive emulsion 10 has an opening 20 composed of a grid electrode opening 41 and a bus electrode opening 42. The grid electrode openings 41 are arranged such that the vertical direction indicated by the arrow X in FIGS. 13 and 14 is the longitudinal direction. The bus electrode openings 42 are arranged such that the left-right direction indicated by the arrow Y in FIGS. 13 and 14 is the longitudinal direction.

  According to the printing mask 2, as shown in FIG. 5, in the portion covered with the photosensitive emulsion 10, the passage of the metal paste 5 to the printing surface side is blocked, and the portion where the screen mesh 9 is exposed, that is, the opening 20 Then, the metal paste 5 is passed to the printing surface side. The mask frame 6 holds the photosensitive emulsion 10 and the screen mesh 9.

  The configuration of the printing mask 2 may be changed as appropriate as long as it has characteristics suitable for screen printing for electrode formation. For example, in the printing mask 2, stainless steel is generally used as a material for the screen mesh. However, the present invention is not limited to this, and the printing mask 2 may use a screen mesh made of a synthetic fiber material or a screen mesh made of a metal material other than stainless steel instead of stainless steel. The printing mask 2 may be used by attaching a metal member pattern to a screen mesh in place of the photosensitive emulsion 10.

  Next, the screen mesh of a general standard printing mask in which one warp and one weft are reticulated for the discharge amount of the metal paste passing through the screen mesh 9 in the printing mask 2 according to the first embodiment. And will be described. FIG. 15 is an enlarged schematic view showing a part of a screen mesh in a general standard printing mask. FIG. 16 is a schematic diagram illustrating an enlarged part of the screen mesh 9 of the printing mask 2 according to the first embodiment. In the drawing, in order to clarify the warp and the weft, only the warp is hatched.

  First, a screen mesh in a general standard printing mask will be described with reference to FIG. A screen mesh in a general standard printing mask is made of a net so that one warp and one weft are alternately switched up and down.

The warp yarn 201 and the warp yarn 202 are formed with the warp yarn wire diameter D1. The weft yarn 203 and the weft yarn 204 are formed with a weft yarn diameter D2. Adjacent warps are arranged with an interval of the warp opening width W1. Adjacent wefts are arranged with a weft opening width W2 therebetween. The warp arrangement pitch P1 is a total value of the warp opening width W1 and the warp wire diameter D1. The weft arrangement pitch P2 is a total value of the weft opening width W2 and the weft wire diameter D2. Arrangement pitch is equivalent to the distance between the center axis of the thread adjacent.

  When the weft passes below the warp, it passes above the warp adjacent to the warp. In addition, when the weft thread passes over the upper side of a certain warp thread, it passes under the warp thread adjacent to the warp thread. By repeating such a netting pattern, the warp and the weft are netted in a plain weave to form a screen mesh. Generally, the warp yarn diameter D1 and the weft yarn diameter D2 are the same, and the warp yarn opening width W1 and the weft yarn opening width W2 are also the same.

  As an index indicating the discharge amount of the metal paste 5 from the screen mesh, an index called transmission thickness T is used. The transmission thickness T will be described with reference to FIG. The metal paste in which the screen mesh opening is filled with the thickness of the screen mesh (hereinafter referred to as “thickness”) is subjected to a printing operation, and when the screen mesh is removed, all of the filling amount in the opening is obtained. Is not discharged. That is, of the metal paste filled in the opening of the screen mesh, a part of the metal paste remains due to the surface tension.

For this reason, the thickness of the printed metal paste is thinner than the thickness by the amount of the metal paste remaining in the opening. Then, after the printing operation is performed and the screen mesh is removed, the height when the metal paste 5 spreads on the substrate is the transmission thickness T. The discharge amount of the metal paste 5 from the screen mesh is an index generally called a permeation volume or a permeation volume, but is an index having a dimension of length. Call. The aperture ratio K is the ratio of the area of the portion where there is no mesh (warp and weft) when the print mask is viewed from above to the entire screen mesh. The thickness TA and the aperture ratio K A transmission in general standard print mask shown in FIG. 15 is expressed by the following equation.

Permeation thickness T A = (opening area × 紗 thickness) / (warp yarn arrangement pitch × weft yarn arrangement pitch)
Opening ratio K A = opening area / (warp yarn arrangement pitch × weft yarn arrangement pitch)
Opening area = warp opening width W1 x weft opening width W2
Warp yarn arrangement pitch P1 = warp yarn opening width W1 + warp yarn wire diameter D1
Weft arrangement pitch P2 = Weft opening width W2 + Weft wire diameter D2

  In a normal case, W1 = W2, D1 = D2, and P1 = P2. The cocoon thickness is generally the same as the value obtained by adding the warp yarn diameter and the weft yarn diameter. Screen meshes that have been crushed after being knitted (hereinafter referred to as calendaring) can be used up to a thickness of about 50% of (warp yarn diameter + weft yarn diameter).

  FIG. 17 is a chart showing a list of calculation examples of the transmission thickness TA in the grid electrode openings (corresponding to the grid electrode openings 41 in the print mask 2 according to the first embodiment) of a general standard print mask. FIG. 17 shows a calculation example of the transmission thickness TA for four types of samples A1 to A4. Here, the warp opening width W1 and the weft opening width W2 are the same (W1 = W2), the warp wire diameter D1 and the weft wire diameter D2 are the same (D1 = D2), and the warp arrangement pitch P1 and the weft arrangement pitch P2 are the same. Were the same (P1 = P2).

  Sample A1 is “200φ40” in which 200 yarns are arranged per inch and yarns having a wire diameter of 40 μm are used. In sample A1, since 200 yarns are arranged per 25.4 mm, the arrangement pitch of the yarns is 25.4 mm / 200 = 127 μm. The opening width is equal to the value obtained by subtracting the wire diameter of the yarn from the arrangement pitch. In sample A1, since the yarn has a wire diameter of 40 μm, the opening width is 87 μm. The thickness was set equal to the thickness of a general screen mesh that was calendered. The thickness shown in FIG. 17 is a value of the thickness of a general screen mesh. In the sample A1 under such conditions, the aperture ratio KA is 46.9%, and the transmission thickness TA is 29.6 μm.

  Sample A2 is “250φ30” in which 250 yarns are arranged per inch and yarns having a wire diameter of 30 μm are used. In sample A2, the arrangement pitch of the yarn is 25.4 mm / 250 pieces = 102 μm. The opening width is equal to the value obtained by subtracting the wire diameter of the yarn from the arrangement pitch. In sample A2, since the yarn has a wire diameter of 30 μm, the opening width is 72 μm. The thickness was set equal to the thickness of a general screen mesh that was calendered. The thickness shown in FIG. 17 is a value of the thickness of a general screen mesh. In the sample A2 under such conditions, the aperture ratio KA is 49.7%, and the transmission thickness TA is 22.8 μm.

  Sample A3 is “290φ20” in which 290 yarns are arranged per inch and yarns having a wire diameter of 20 μm are used. In sample A3, the arrangement pitch of the yarn is 25.4 mm / 290 pieces = 88 μm. The opening width is equal to the value obtained by subtracting the wire diameter of the yarn from the arrangement pitch. In sample A3, since the yarn has a wire diameter of 20 μm, the opening width is 68 μm. The thickness was set equal to the thickness of a general screen mesh that was calendered. The thickness shown in FIG. 17 is a value of the thickness of a general screen mesh. In the sample A3 under such conditions, the aperture ratio KA is 59.5% and the transmission thickness TA is 20.8 μm.

  Sample A4 is “360φ16” in which 360 yarns are arranged per inch and yarns having a wire diameter of 16 μm are used. In the sample A4, the arrangement pitch of the yarn is 25.4 mm / 360 pieces = 71 μm. The opening width is equal to the value obtained by subtracting the wire diameter of the yarn from the arrangement pitch. In sample A4, since the wire diameter of the yarn is 16 μm, the opening width is 55 μm. The thickness was set equal to the thickness of a general screen mesh that was calendered. The thickness shown in FIG. 17 is a value of the thickness of a general screen mesh. In sample A4 under such conditions, the aperture ratio KA is 59.8% and the transmission thickness TA is 16.7 μm.

Next, the screen mesh 9 in the printing mask 2 according to the first embodiment will be described with reference to FIG. The configuration of the screen mesh 9 in the printing mask 2 according to the first embodiment is that of a general standard printing mask except that twisted yarns in which two component yarns are twisted and knitted are used for warp yarns and weft yarns. It is the same as the screen mesh configuration. Luz clean mesh 9 put in the printing mask 2, one of the warp (yarn) and one weft and (strands) are manufactured network in plain weave so as switch the top and bottom alternately.

  The warp yarn 111, the warp yarn 112, and the warp yarn 113 are each constituted by a twisted yarn obtained by twisting and knitting a constituent yarn 131 having a warp wire diameter D3 and a constituent yarn 132 having a warp wire diameter D4. The weft yarn 121, the weft yarn 122, and the weft yarn 123 are each composed of a twisted yarn in which a constituent yarn 133 having a weft yarn diameter D5 and a constituent yarn 134 having a weft yarn diameter D6 are twisted and knitted. Adjacent warps are arranged with an interval of the warp opening width W3. Adjacent wefts are arranged with an interval of the weft opening width W4. The warp arrangement pitch P3 is a total value of the warp opening width W3, the warp wire diameter D3, and the warp wire diameter D4. The weft arrangement pitch P4 is a total value of the weft opening width W4, the weft yarn diameter D5, and the weft yarn diameter D6. The arrangement pitch corresponds to the distance between the central axes of adjacent yarns.

  When the weft passes below the warp, it passes above the warp adjacent to the warp. In addition, when the weft thread passes over the upper side of a certain warp thread, it passes under the warp thread adjacent to the warp thread. The screen mesh 9 is configured by repeating such a netting pattern and netting warp and weft in plain weave. The transmission thickness TB and the aperture ratio KB in the printing mask 2 shown in FIG. 16 are expressed by the following equations.

Permeation thickness TB = (opening area × thickness) / (warp arrangement pitch × weft arrangement pitch)
Opening ratio KB = opening area / (warp yarn arrangement pitch × weft yarn arrangement pitch)
Opening area = warp opening width W3 x weft opening width W4
Warp yarn arrangement pitch P3 = warp yarn opening width W3 + warp yarn wire diameter D3 + warp yarn wire diameter D4
Weft arrangement pitch P4 = Weft opening width W4 + Weft wire diameter D5 + Weft wire diameter D6

  As an example, W3 = W4, D3 = D4 = D5 = D6, and P3 = P4. The cocoon thickness is, for example, the same as the value obtained by adding the warp yarn diameter and the weft yarn diameter. The screen mesh 9 subjected to calendering after knitting yarn can be used up to a thickness of about 50% of (warp yarn diameter + weft yarn diameter).

  FIG. 18 is a chart showing a list of calculation examples of the transmission thickness TB in the grid electrode openings 41 of the printing mask 2 according to the first embodiment. FIG. 18 shows a calculation example of the transmission thickness TB for four types of samples B1 to B4. Here, the warp opening width W3 and the weft opening width W4 are the same (W3 = W4), and the warp wire diameter D3, the warp wire diameter D4, the weft wire diameter D5, and the weft wire diameter D6 are the same (D3 = D4 = D5 = D6), the warp yarn arrangement pitch P3 and the weft yarn arrangement pitch P4 are the same (P3 = P4). The warp yarn arrangement pitch P3 and the weft yarn arrangement pitch P4 are the same as the warp yarn arrangement pitch P1 of the screen mesh of a general standard printing which is a comparative example.

  Sample B1 is a “200φ40 double” in which 200 yarns per inch are arranged, and twisted yarns obtained by twisting and knitting two yarns having a wire diameter of 40 μm are used as warp yarns and weft yarns. 200 here means 200 twisted yarns. In sample B1, since 200 twisted yarns are arranged per 25.4 mm, the arrangement pitch of the twisted yarns is 25.4 mm / 200 = 127 μm. The opening width is equal to the value obtained by subtracting the wire diameter of the twisted yarn from the arrangement pitch. In the sample B1, the warp wire diameter D3 and the warp wire diameter D4 are 40 μm, and the apparent wire diameter of the twisted yarn is doubled to 80 μm (inside () in the wire diameter column in FIG. 18). However, the apparent wire diameter Da of the twisted yarn becomes 63 μm by performing calendar processing similar to general standard printing. Therefore, in the sample B1, the opening width is 64 μm, which is a value obtained by subtracting the apparent wire diameter Da of the twisted yarn from the arrangement pitch. The cocoon thickness was a value obtained by simply knitting a twisted yarn (twice the apparent wire diameter Da of the twisted yarn). In the sample B1 under such conditions, the aperture ratio KB is 25.4%, and the transmission thickness TB is 32.0 μm.

  Sample B2 is a “250φ30 double” in which 250 yarns per inch are used, and twisted yarns in which two yarns having a wire diameter of 30 μm are twisted and knitted are used as warp yarns and weft yarns. The 250 here means 250 twisted yarns. In sample B2, since 250 twisted yarns are arranged per 25.4 mm, the arrangement pitch of the twisted yarns is 25.4 mm / 250 = 102 μm. The opening width is equal to the value obtained by subtracting the wire diameter of the twisted yarn from the arrangement pitch. In the sample B2, the warp wire diameter D3 and the warp wire diameter D4 are 30 μm, and the apparent wire diameter of the twisted yarn is doubled to 60 μm (inside () in the wire diameter column in FIG. 18). However, the apparent wire diameter Da of the twisted yarn becomes 46 [mu] m by performing calendar processing similar to general standard printing. Therefore, in sample B2, the opening width is 56 μm, which is a value obtained by subtracting the apparent wire diameter Da of the twisted yarn from the arrangement pitch. The cocoon thickness was a value obtained by simply knitting a twisted yarn (twice the apparent wire diameter Da of the twisted yarn). In the sample B2 under such conditions, the aperture ratio KB is 30.1%, and the transmission thickness TB is 27.7 μm.

  Sample B3 is a “290φ20 double” in which 290 yarns per inch are arranged, and twisted yarns obtained by twisting and knitting two yarns having a wire diameter of 20 μm are used as warp yarns and weft yarns. 290 here means 290 twisted yarns. In sample B3, since 290 twisted yarns are arranged per 25.4 mm, the arrangement pitch of the twisted yarns is 25.4 mm / 290 = 88 μm. The opening width is equal to the value obtained by subtracting the wire diameter of the twisted yarn from the arrangement pitch. In sample B3, the warp wire diameter D3 and the warp wire diameter D4 are 20 μm, and the apparent wire diameter of the twisted yarn is doubled to 40 μm (inside () in the column of the wire diameter in FIG. 18). However, the apparent wire diameter Da of the twisted yarn becomes 35 μm by performing calendar processing similar to general standard printing. Therefore, in sample B3, the opening width is 53 μm, which is a value obtained by subtracting the apparent wire diameter Da of the twisted yarn from the arrangement pitch. The cocoon thickness was a value obtained by simply knitting a twisted yarn (twice the apparent wire diameter Da of the twisted yarn). In the sample B3 under such conditions, the aperture ratio KB is 36.3%, and the transmission thickness TB is 25.4 μm.

  Sample B4 is a “360φ16 double” in which 360 yarns are arranged per inch and two yarns having a wire diameter of 16 μm are twisted and knitted as warp yarns and weft yarns. Here, 360 means 360 twisted yarns. In sample B4, since 360 twisted yarns are arranged per 25.4 mm, the arrangement pitch of the twisted yarns is 25.4 mm / 360 = 71 μm. The opening width is equal to the value obtained by subtracting the wire diameter of the twisted yarn from the arrangement pitch. In sample B4, the warp wire diameter D3 and the warp wire diameter D4 are 16 μm, and the apparent wire diameter of the twisted yarn is doubled to 32 μm (inside () in the wire diameter column in FIG. 18). However, the apparent wire diameter Da of the twisted yarn becomes 28 μm by performing calendar processing similar to general standard printing. Therefore, in sample B4, the opening width is 43 μm, which is a value obtained by subtracting the apparent wire diameter Da of the twisted yarn from the arrangement pitch. The cocoon thickness was a value obtained by simply knitting a twisted yarn (twice the apparent wire diameter Da of the twisted yarn). In the sample B4 under such conditions, the aperture ratio KB is 36.7%, and the transmission thickness TB is 20.5 μm.

  FIG. 19 is a table showing a list of relative paste usage ratios of the screen mesh of the printing mask according to the first embodiment with respect to the screen mesh of a general standard printing mask. FIG. 19 is obtained based on FIG. 17 and FIG.

  For example, the sample B1: “200φ40 double” of the printing mask 2 according to the first embodiment has the same arrangement pitch of 127 μm as compared with the sample A1: “200φ40” of a general standard printing mask, but the opening width is the same. The aperture ratio decreases from 46.9% to 25.4% because the size decreases from 87 μm to 64 μm. On the other hand, the transmission thickness increases from 29.6 μm to 32.0 μm. The value obtained by multiplying the transmission thickness and the aperture ratio is reduced from 13.9 to 8.1, and the ratio is 58.6%.

  That is, assuming that the amount of the metal paste included in the screen mesh of a general standard printing mask sample A1: “200φ40” is 1, the screen of the sample B1: “200φ40 double” of the printing mask 2 according to the first embodiment. The amount of the metal paste included in the mesh 9 is 0.586. Similarly, assuming that the amount of metal paste contained in the screen mesh of sample A2: “250φ30” is 1, the amount of metal paste contained in the screen mesh 9 of sample B2: “250φ30 double” is 0.737. .

  Similarly, if the amount of metal paste contained in the screen mesh of sample A3: “290φ20” is 1, the amount of metal paste contained in the screen mesh 9 of sample B3: “290φ20 double” is 0.742. . Similarly, assuming that the amount of metal paste contained in the screen mesh of sample A4: “360φ16” is 1, the amount of metal paste contained in the screen mesh 9 of sample B4: “360φ16 double” is 0.753. .

  In such a screen mesh 9, one part and two parts of the constituent yarn are alternately arranged on one side of the shielding portion by the twisted yarn when the screen mesh 9 is viewed from the upper surface. For this reason, even when the arrangement pitch is the same, the opening width becomes narrower and the opening ratio becomes smaller than in the case of plain weaving one yarn. On the other hand, in the screen mesh 9, since the twisted yarn is knitted by twisting two constituent yarns, the thickness of the printing mask 2 is higher than that when plain weaving one yarn. For example, although depending on the degree of calendering, the height is higher than two component yarns, lower than four, and on average can be as high as three component yarns. That is, in the screen mesh 9, the aperture ratio can be reduced and the thickness can be increased by adjusting the wire diameter of the constituent yarn and the degree of calendering.

  Thus, by performing screen printing of the grid electrode using the printing mask 2 according to the first embodiment, the transmission thickness is increased while drawing and printing a fine fine line electrode pattern while suppressing the aperture ratio. Can do. Therefore, by performing screen printing of the grid electrode using the printing mask 2 according to the first embodiment, the thickness of the grid electrode is ensured to be thick while the width of the grid electrode is narrowed, and the thin line electrode is difficult to be disconnected. Can be realized. Thereby, while reducing the shadow loss in the light-receiving surface side of a solar cell, the electrical resistance of an electrode can be reduced and resistance loss can be reduced, and the power generation efficiency of a solar cell can be improved.

  In addition, by performing screen printing of the bus electrodes using the printing mask 2 according to the first embodiment, the amount of paste itself included in the screen mesh 9 can be reduced. Therefore, the amount of paste used for the bus electrode can be suppressed, and the amount of paste used can be suppressed for the entire electrode printing. Thereby, the cost of an electrode can be reduced and the manufacturing cost of a solar cell can be reduced.

  That is, by performing screen printing using the printing mask 2 using the screen mesh 9 made by twisting and knitting the two constituent yarns, the metal paste necessary for printing the light receiving surface side electrode The metal paste 5 sufficient to draw the thick grid electrode 21 can be supplied while suppressing the amount of use of the entire 5. Thereby, while improving the power generation efficiency of a solar cell, the manufacturing cost of a solar cell can be reduced.

  In the above description, the case where the twisted yarn is used for both the warp and the weft has been described. However, the twisted yarn may be used for at least one of the warp and the weft. However, in order to obtain a sufficient effect, it is preferable to use twisted yarns for both the warp and the weft.

  Moreover, in the above, although the effect when the wire diameter of a warp (twisted yarn) and the wire diameter of a weft (twisted yarn) was the same was demonstrated, the wire diameter of a warp (twisted yarn) and the wire diameter of a weft (twisted yarn) are different. Even when the wire diameter is changed, the same effect as described above can be obtained. Moreover, in the above, although the effect in the case where the wire diameters of the two constituent yarns constituting the warp yarn (twisted yarn) are the same was described, the wire diameters of the two constituent yarns constituting the warp yarn (twisted yarn) are different from each other. Even when the diameter is changed, the same effect as described above can be obtained. You may change each wire diameter. Similarly, even when the wire diameters of the two constituent yarns constituting the weft yarn (twisted yarn) are changed to different wire diameters, the same effect as described above can be obtained. In addition, the same effect as described above can be obtained even when two constituent yarns constituting each of the warp and weft yarns, that is, all four constituent yarns have different wire diameters. Thus, by adjusting the wire diameter of the constituent yarn and changing the configuration of the twisted yarn, the interval between adjacent warp yarns or the arrangement pitch of the warp yarns can be freely changed. Moreover, the space | interval of adjacent wefts or the arrangement pitch of a weft can be changed freely. Thereby, it is possible to adjust an aperture ratio and permeation | transmission thickness to an appropriate value according to an electrode pattern.

  Further, by using the printing mask 2 according to the first embodiment, the amount of metal paste used for electrode printing can be reduced even when a general printing machine is used. For this reason, except for using the printing mask 2 according to the first embodiment as a printing mask, a thin screen electrode having a large thickness is drawn by a general screen printing method, and the amount of metal paste used as the whole electrode is reduced. Is possible. Moreover, the screen printing mentioned above can be easily implemented only by changing a printing mask into the printing mask 2 concerning Embodiment 1 in a general printing machine, and it is excellent in versatility. The print mask 2 according to the first embodiment is particularly useful for forming the light receiving surface side electrode of the solar cell.

  In addition, when the arrangement pitch is the same and two warp yarns (weft yarns) in which two constituent yarns are arranged side by side are used, the above-described effects cannot be obtained. That is, when the warp yarn (weft yarn) is configured by simply arranging two constituent yarns side by side, the aperture ratio can be reduced, but the thickness cannot be increased.

  As described above, in the first embodiment, in the screen printing of the electrodes, a printing mask using a screen mesh made of a twisted yarn in which two constituent yarns are twisted and knitted is used. As a result, it is possible to form an electrode having an electrode height that is difficult to break even when printing a thinned grid electrode. In addition, the amount of metal paste used can be reduced in printing bus electrodes. Therefore, according to Embodiment 1, while improving the power generation efficiency of a solar cell, the manufacturing cost of a solar cell can be reduced. As described above, the solar cell manufacturing method, the printing mask, and the solar cell according to the first embodiment are useful for reducing the cost of the solar cell.

Embodiment 2. FIG.
Next, a solar battery module using the solar battery cell 1 manufactured by the solar battery manufacturing method according to the first embodiment will be described. 20 and 21 are schematic cross-sectional views illustrating the procedure of the method for manufacturing the solar cell module according to the second embodiment. 20 and 21 show the state where the upper side is installed as the light receiving surface (front surface), but when assembling the solar cell module, the assembly is performed with the top and bottom inverted in FIGS. 20 and 21.

  First, the translucent resin member 52 is installed on the translucent substrate 51. Next, the solar cell 53 with wiring is installed on the translucent resin member 52. The solar cell with wiring 53 is a solar cell adjacent to a predetermined number of solar cells 1 (see FIGS. 1 to 3) that are manufactured by using the method for manufacturing a solar cell according to the first embodiment. The first front bus electrodes 22 are connected to each other by a soldered copper wire or the like which is a connecting member, so that they are electrically connected in series. The material used for the wiring may be any conductive material other than the copper wire with solder. The solar cell with wiring 53 is installed on the translucent resin member 52 with the back surface of each solar cell 1 facing upward.

  Next, the translucent resin member 52 and the back sheet 54 are installed in this order on the solar cell 53 with wiring. FIG. 20 shows a state in which the light-transmitting substrate 51, the light-transmitting resin member 52, the solar cell with wiring 53, the light-transmitting resin member 52, and the back sheet 54 are stacked in order from the top of the figure.

  By performing a heat treatment in a state in which these members are pressure-bonded, as shown in FIG. 21, a translucent resin layer 55 in which the solar cell with wiring 53 is sealed, a translucent substrate 51, and a back sheet. Thus, a solar cell module integrated with 54 is produced. By using the solar battery cell 1 including the electrode formed by the method for forming a solar battery according to the first embodiment, a solar battery with high power generation efficiency can be manufactured at a low manufacturing cost.

  It is desirable to use a vacuum thermocompression bonding device called a laminator for the heating and pressure bonding processes in the production of the solar cell module. The laminator heats and deforms the translucent resin member 52 and the back sheet 54 and further thermosets them to seal the solar cell in the translucent resin layer 55.

  The vacuum thermocompression bonding apparatus heats and crimps each member in a reduced pressure environment. Thereby, between the translucent board | substrate 51 and the translucent resin member 52, between the translucent resin member 52 and the solar cell 53 with wiring, between the solar cell 53 with wiring, and the translucent resin member 52, translucent resin member In any of the space between the back sheet 54 and the back sheet 54, it is possible to prevent gaps and bubbles from remaining, and to press-bond each member with a uniform pressure.

  The heating and pressure-bonding treatment in the vacuum thermocompression bonding apparatus is performed at a temperature of 200 degrees or less, desirably 150 degrees to 200 degrees. It is assumed that the temperature in the heating and pressure bonding processes can be changed as appropriate depending on the material of the translucent resin member 52 and the like.

  As the translucent substrate 51, for example, a glass substrate is used. The translucent board | substrate 51 should just be what can permeate | transmit sunlight, and is good also as what consists of materials other than glass. The translucent resin member 52 is one of resins such as ethylene vinyl acetate, polyvinyl butyral, epoxy, acrylic, urethane, olefin, polyester, silicon, polystyrene, polycarbonate, and rubber. Contains one or more. As long as the translucent resin member 52 can transmit sunlight, any material other than those listed here may be used.

  As the back sheet 54, a sheet made of one or a plurality of resins such as polyester, polyvinyl, polycarbonate, and polyimide is used. The back sheet 54 may be made of any material other than those listed here as long as it has sufficient strength, moisture resistance and weather resistance for protecting the solar cell module. The back sheet 54 may be made of not only a resin material but also a composite material in which a metal foil material is bonded to improve strength, moisture resistance, and weather resistance. Further, the back sheet 54 may be formed by bonding a metal material having a high light reflectance or a transparent member having a high refractive index to a resin material by vapor deposition or the like.

  The end face of the solar cell module may be protected with a tape made of a rubber-based resin member or the like in order to improve the adhesion of the laminating process and prevent intrusion of moisture or the like from the outside. For example, butyl rubber or the like is used as the rubber-based resin member. Furthermore, the solar cell module may be provided with a frame surrounding the outer periphery in view of ease of handling as a structure. The frame is configured using a metal member such as aluminum or an aluminum alloy, for example.

  According to the second embodiment, a solar battery module is manufactured using the solar battery cell 1 manufactured by the method for manufacturing a solar battery according to the first embodiment. As a result, an inexpensive solar cell module with high power generation efficiency can be obtained by a simple method without changing the general method for manufacturing a solar cell module. Therefore, the manufacturing method of the solar cell according to the first embodiment and the manufacturing method of the solar cell module according to the second embodiment are very useful industrially.

  As described above, the method for manufacturing a solar cell according to the present invention is useful for manufacturing a solar cell with high power generation efficiency.

  1 Solar cell, 2 Print mask, 3 Substrate material, 4 Stage, 5 Metal paste, 6 Mask frame, 7 Suction mechanism, 8 Squeegee, 9 Screen mesh, 10 Photosensitive emulsion, 11 Warp, 12 Weft, 13 Outer edge side, 14 margin, 20 opening, 21 grid electrode, 22 front bus electrode, 23 back aluminum electrode, 24 back bus electrode, 31 p-type silicon substrate, 32 n-type impurity diffusion layer, 33 antireflection film, 41 grid electrode opening, 42 bus electrode opening, 51 translucent substrate, 52 translucent resin member, 53 solar cell, 54 back sheet, 55 translucent resin layer, 111, 112, 113 warp, 121, 122, 123 weft, 131, 132, 133, 134 Constituent yarn, 201, 202 warp, 203, 204 weft, D1, D3, D4 warp Yarn wire diameter, D2, D5, D6 Weft yarn diameter, Da apparent wire diameter of twisted yarn, width of one side in M square shape, width equivalent to one side in M ′ rounded square shape, P1, P3 warp yarn arrangement pitch, P2, P4 Weft arrangement pitch, W1, W3 warp opening width, W2, W4 weft opening width.

Claims (4)

A sun including a screen printing process in which a paste containing a conductive material as an electrode material is applied to an electrode forming surface of a substrate through a printing mask having an opening corresponding to an electrode shape having a bus electrode portion and a grid electrode portion. A battery manufacturing method comprising:
In the screen printing process, the printing is performed in which a screen mesh formed by using a twisted yarn knitted by twisting two constituent yarns made of a metal material as at least one of a warp and a weft is provided in the opening. Applying the paste using a mask;
A method for manufacturing a solar cell.   The wire diameters of the two constituent yarns are the same,
  The thickness of the printing mask is higher than two of the constituent yarns and lower than four of the constituent yarns;
  The manufacturing method of the solar cell of Claim 1 characterized by these. A printing mask used when applying a paste containing a conductive material, which is an electrode material, to the electrode forming surface of a substrate by screen printing,
The screen mesh for holding the paste is made by using a twisted yarn in which two constituent yarns made of a metal material are twisted and knitted as at least one of a warp yarn or a weft yarn,
Print mask characterized by.   The wire diameters of the two constituent yarns are the same,
  The thickness of the printing mask is higher than two of the constituent yarns and lower than four of the constituent yarns;
  The printing mask according to claim 3.

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