JP5919656B2 - Conductive substrate for wiring pattern formation of current collector sheet for solar cell - Google Patents

Description

  The present invention relates to a conductive base material for forming a wiring pattern of a solar cell current collector sheet used as wiring inside a solar cell module.

  In recent years, solar cells as a clean energy source have attracted attention due to the growing awareness of environmental issues. Generally, a solar cell module constituting a solar cell has a configuration in which a transparent front substrate, a front surface side sealing material sheet, a solar cell element, a back side sealing material sheet, and a back surface protection sheet are laminated in order from the light receiving surface side. Yes, it has a function of generating power when sunlight enters the solar cell element.

  A plurality of solar cell elements that generate power inside the solar cell module are usually provided inside the solar cell module, and are configured to obtain necessary voltages and currents by connecting them in series and parallel. . In order to wire a plurality of solar cell elements inside the solar cell module, for example, a solar cell current collector sheet in which a metal foil to be a wiring pattern is laminated on the surface of a resin sheet as a base material is used (patent) Reference 1). And the wiring pattern which consists of metal foil, and the output electrode of a solar cell element are electrically joined by soldering.

  In order to provide a wiring pattern on the surface of a resin sheet that is a base material for a solar cell current collector sheet, for example, similarly to a printed wiring board, first, a conductive base material made of a metal foil or the like on the entire surface of the base material. Then, the conductive base material may be etched by photolithography so as to form a desired wiring pattern.

  By the way, the surface of the copper foil generally used as the conductive substrate is very easily oxidized. And the surface of the oxidized copper foil is remarkably inferior in wettability to solder. Therefore, the surface of the copper foil used as a wiring pattern needs rust prevention processing. In this respect, in a printed wiring board, a method of applying a rust-preventing coating on the surface of a copper foil to be a wiring pattern (see Patent Document 2), and a method of forming a coating formed with a complex structure with copper on the surface of the wiring pattern ( As described in Patent Document 3), the surface of the conductive base material to be a wiring pattern is subjected to rust prevention treatment using an organic rust inhibitor. The printed wiring board that has been subjected to such rust prevention treatment suppresses the oxidation of the surface of the wiring pattern, so that good wettability with respect to solder is maintained, and the electronic component is surely attached to the printed wiring board by soldering. From the viewpoint of proper mounting, it is preferable.

  However, a solar cell current collector sheet is used in a state of being bonded to a solar cell element while being exposed to sunlight for a long period of decades. For this reason, when an anticorrosive treatment using an organic anticorrosive agent is applied like a printed wiring board, the organic anticorrosive agent itself or itself decomposes during the long-term use. The compound produced in this manner may adversely affect the solar cell element and cause the performance deterioration of the solar cell module.

  The conductive base material that forms the wiring pattern of the solar cell current collector sheet requires rust prevention treatment without using an organic rust inhibitor. As such a rust-proofing process, the process which provides a rust-proof layer on copper foil by the plating containing chromium and zinc is performed (refer patent document 4). However, when anti-corrosion treatment with chromium / zinc is applied, the adverse effect on the solar cell element as in the case of using an organic anti-corrosion agent is reduced, while the wettability of the wiring pattern to the solder is reduced. There was a problem that the reliability of joining by soldering between the electrode of the solar cell element and the current collector sheet for solar cell was lowered significantly.

  As described above, there is a conductive base material for forming a wiring pattern of a solar cell current collector sheet that has both rust prevention, stability to solar cell elements, and good solderability (ie, wettability to solder). The current situation is not.

JP 2007-081237 A Japanese Patent Laid-Open No. 9-326549 JP-A-6-006018 JP 2000-178787 A

  The present invention has been made in view of the situation as described above, and has good rust prevention and solderability without using an organic rust inhibitor that may adversely affect solar cell elements. It is an object of the present invention to provide a conductive substrate that can be suitably used for forming a wiring pattern of a solar cell current collector sheet provided with

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained a predetermined amount of adhesion on the surface of the copper foil without using chromium, which is generally considered essential as a rust inhibitor. By using a conductive base material formed with a protective film made of zinc for wiring pattern formation, it was found that the wiring pattern of a solar cell current collector sheet can achieve both good rust prevention and solderability. The invention has been completed. More specifically, the present invention provides the following.

(1) A conductive base material used for a wiring pattern of a solar cell current collector sheet, the adhesion amount of which exceeds 20 mg / m ² and is 40 mg / m ² on at least one surface of a copper foil having a thickness of 10 μm to 35 μm. A conductive base material, wherein a zinc layer of ² or less is formed.

  (2) The conductive base material according to (1), wherein the copper foil is formed of electrolytic foil, wherein the zinc layer is formed on the glossy surface of the copper foil. Base material.

  (3) The conductive base material according to (1) or (2), wherein one or more functional enhancement layers are further formed on the zinc layer of the copper foil, wherein the functional enhancement layers The conductive substrate according to (1) or (2), wherein none of the layers contains chromium.

(4) A lamination step of laminating the conductive substrate according to any one of (1) to (3) with a resin substrate to obtain a laminate, and an etching mask patterned into a desired wiring pattern shape An etching process is performed after forming the surface of the laminate to remove the conductive base material in a portion not covered with the etching mask, and an alkaline stripping solution is used after the etching process. A step of removing the etching mask, and a method for producing a solar cell current collector sheet, wherein in the peeling step, the etching mask is peeled off, and a part of the surface of the zinc layer is made alkaline. is removed by the stripping solution, the wiring path anticorrosive protective layer is 20 mg / ^{m 2} or less adhesion amount exceeds the 0.5 mg / ^{m 2} of said zinc Method for producing a current collector sheet for a solar cell, characterized in that to form on the surface of the over down.

  ADVANTAGE OF THE INVENTION According to this invention, the wiring pattern of the current collection sheet | seat for solar cells provided with favorable rust prevention property and solderability, without using the organic type rust preventive agent which may have a bad influence on a solar cell element A conductive substrate for forming is provided.

It is a schematic diagram which shows the laminated constitution of the electroconductive base material for wiring pattern formation of the collector sheet for solar cells of this invention. It is a schematic diagram which shows the collector sheet for solar cells using the electroconductive base material for wiring pattern formation of the collector sheet for solar cells of this invention, (a) is a top view, (b) is (a). It is a longitudinal cross-sectional view in the AA line. (A)-(d) is a schematic diagram which shows sequentially a mode that a wiring pattern is formed by one embodiment of the manufacturing method of the wiring sheet of this invention. It is a graph which shows the relationship between the surface zinc amount in Example 2, and solder height.

  Hereinafter, a conductive base material for forming a wiring pattern of a solar cell current collector sheet of the present invention (hereinafter, also simply referred to as “conductive base material”), and a wiring pattern for forming a solar cell current collector sheet of the present invention. The manufacturing method of the current collection sheet for solar cells using an electroconductive base material is demonstrated.

<Conductive substrate for wiring pattern formation of current collector sheet for solar cell>
First, the conductive base material 10 for forming the wiring pattern of the solar cell current collector sheet of the present invention will be described with reference to FIG. FIG. 1 is a schematic view showing a layer structure of a conductive substrate 10 for forming a wiring pattern of a solar cell current collector sheet of the present invention.

  The conductive substrate 10 is a conductive thin film in which a zinc layer 12 is formed on at least one surface of a copper foil 11, and the solar cell current collector sheet 1 (see FIG. 2) is manufactured by a manufacturing method described in detail later. ) Can be suitably used as a base material constituting the wiring pattern 10a. The other surface of the copper foil 11 on which the zinc layer 12 is not formed in the conductive substrate 10 is not particularly limited in the layer structure and the like, but it is preferable that at least some rust prevention treatment is applied. In the conductive base material 10, a back zinc layer 13 made of zinc is formed.

  The copper foil 11 becomes a conductive portion of the wiring pattern 10a when the conductive substrate 10 becomes the wiring pattern 10a in the solar cell current collector sheet 1. The wiring pattern 10a is required to have high conductivity and processability at the time of molding, but the copper foil 11 sufficiently satisfies these conditions.

  What is necessary is just to set the thickness of the copper foil 11 suitably according to the magnitude | size of the electric current resistance etc. which are requested | required of the collector sheet 1 for solar cells (refer FIG. 2) demonstrated in detail later. Although the thickness of the copper foil 11 is not specifically limited, 10-35 micrometers is mentioned as an example.

  The copper foil 11 can be made by a conventionally known manufacturing method including an electrolytic method and a rolling method. The production method is not particularly limited, but a preferable example is an electrolytic foil-making method. The electrolytic foil-making method includes a rotating drum anode partially immersed in an electrolytic bath, and an arcuate cathode facing the space between the rotating drum anode and copper in the rotating drum. This is a manufacturing method in which a copper foil is made by electrodeposition and finally peeling a copper foil having a predetermined thickness from a drum. In the copper foil produced by this method, the surface on the side that was in close contact with the rotating drum at the time of foil production becomes a glossy surface with extremely small surface roughness, and the surface on the opposite side has a relatively large surface roughness. It becomes a conversion surface.

  As the copper foil 11 constituting the conductive base material 10, a copper foil having a glossy surface and a roughened surface as described above can be particularly preferably used. When the copper foil 11 having a glossy surface and a roughened surface is used as the copper foil 11, a conductive substrate 10 having particularly excellent solderability is manufactured by forming a zinc layer 12 described in detail below on the glossy surface side. can do.

  The zinc layer 12 is a layer made of zinc formed in a thin film on one surface of the copper foil 11, preferably a glossy surface, in order to suppress oxidation of the surface of the copper foil 11. Here, when the surface of the conductive substrate 10 on which the zinc layer 12 is formed is used as the wiring pattern 10a of the solar cell collector sheet 1, the wiring pattern 10a is joined to the electrode of the solar cell element. This is the side surface (see FIG. 2). Therefore, solderability is required for the surface on which the zinc layer 12 is formed in addition to rust prevention. Conventionally, when performing a rust prevention treatment without using an organic rust inhibitor on the surface of a copper foil, it has been essential to form a chromium layer in addition to a zinc layer. 10 is to secure a necessary rust prevention property in a solar cell current collector sheet by forming a zinc layer limited to a certain adhesion amount on the surface to be bonded to the electrode of the solar cell element, and at least When the solar cell current collector sheet is used as a wiring pattern, it is characterized in that the soldering suitability is improved by making this surface chromeless.

  The method for forming the zinc layer 12 on the surface of the copper foil 11 is not particularly limited, and can be formed by galvanization, zinc sputtering or vapor deposition. Especially, a conventionally well-known electroplating method can be used preferably. In addition to zinc, the plating solution may contain a complexing agent or ammonia water as required. As plating conditions, it is preferable that the temperature of the plating solution is in the range of 15 ° C to 50 ° C.

  Here, as will be described in detail later, the zinc layer 12 of the conductive base material 10 is a surface of the anticorrosive protective layer 12a remaining on the wiring pattern 10a during the peeling process for removing the etching mask after the etching process. The portion is deleted, and finally, in the wiring pattern 10a, the rust prevention protective layer 12b is thinner than the original zinc layer 12 (see FIG. 3). When the conductive base material 10 becomes the wiring pattern 10a in the solar cell current collector sheet 1, the zinc layer in advance is adjusted so that the amount of zinc attached to the rust prevention protective layer 12b becomes an appropriate amount described below. By adjusting the amount of zinc 12 to an appropriate range, the wiring pattern 10a of the solar cell collector sheet 1 is imparted with rust prevention, stability to solar cell elements, and good solderability. It is possible.

Specifically, in the state where the conductive substrate 10 becomes the wiring pattern 10a of the solar cell current collector sheet 1, the amount of zinc that forms the rust-preventing protective layer 12b on the surface of the conductive layer 11a is: It is preferably more than 0.5 mg / m ² and not more than 20 mg / m ² . When the adhesion amount of zinc forming the rust prevention protective layer 12b is within this range, the solar cell current collector sheet 1 may have both rust prevention, stability to solar cell elements, and good solderability. it can.

  The amount of zinc attached is extremely small to form a thin film. Therefore, it is considered that such a thin film formed of a small amount of zinc has a thickness of several atoms, and it is considered that defects of the film are generated in some places. Since such a film defect exists, the copper of the conductive layer 11a existing under the rust preventive protective layer 12b is exposed in some places, so that both solderability and rust resistance can be achieved. it is conceivable that.

In order to make the adhesion amount of the rust prevention protective layer 12b finally formed on the wiring pattern 10a of the solar cell current collector sheet 1 within the above range, the conductive base material 10 is formed on the copper foil 11. The amount of zinc deposited on the zinc layer 12 exceeds 20 mg / m ² and is 40 mg / m ² or less. Further, it is more preferable exceed 25 mg / ^{m 2} is 35 mg / ^{m 2} or less. When the adhesion amount of the zinc in the zinc layer 12 is less than 20 mg / ^{m 2,} the adhesion amount of the zinc to form an anticorrosive protective layer 12b after the etching process it is difficult to to exceed 0.5 mg / ^{m 2,} The rust prevention property of the wiring pattern 10a becomes insufficient. Moreover, when the zinc adhesion amount in the zinc layer 12 exceeds 40 mg / m ² , the zinc adhesion amount forming the rust prevention protective layer 12b when etching is performed under general conditions exceeds 20 mg / m ^2. As a result, the solderability of the wiring pattern 10a is degraded. Moreover, although it is possible to increase the removal amount of zinc in order to prevent it, it is not preferable because the cost of zinc to be removed increases.

In the present invention, as described above, in the conductive base material 10, the zinc layer 12 made of zinc is formed on the surface of the copper foil 11 with a specific adhesion amount, so that the current collector sheet 1 for a solar cell as a final product is formed. To achieve both solder processability and rust prevention. Originally, zinc has poor adhesion to solder. However, the present inventors surprisingly found that the amount of zinc that forms the rust-preventing protective layer 12b formed on the surface of the conductive layer 11a of the wiring pattern 10a of the solar cell collector sheet 1 is 0.5 mg / kg. By setting it to 20 mg / m ² or more exceeding m ² , it is possible to suppress a decrease in solder processability due to zinc and to sufficiently oxidize copper constituting the conductive layer 11a within a period of about two months. It is found that the amount of zinc adhering to the zinc layer 12 is more than 20 mg / m ² and not more than 40 mg / m ^{2 in the} conductive substrate 10 which is a constituent material of the wiring pattern 10a. Thus, it has been found that the oxidation of copper constituting the copper foil 11 can be sufficiently suppressed within a period of about three months. The present invention has been completed based on such findings.

  In the solar cell current collector sheet, an extremely high antirust property is required for the oxidation of the wiring pattern before joining with the solar cell element, but after being integrated as a solar cell module, The surface is covered with solder, and the components of the solar cell module have a high gas barrier property, so that the oxidation of the copper foil is difficult to proceed. It doesn't matter if it exists. Therefore, there is no shortage in practice as long as the necessary rust prevention performance can be exhibited within the time as described above. From such circumstances, the conductive substrate of the present invention can be used as a very suitable member when the use thereof is for forming a wiring pattern of a solar cell collector sheet.

  The surface opposite to the surface on which the zinc layer 12 is formed in the conductive substrate 10 is bonded to the resin substrate 20 in the wiring pattern 10a when used as the wiring pattern 10a of the solar cell current collector sheet 1. It becomes the surface to do. Therefore, high rust resistance and solderability as high as the surface on which the zinc layer 12 is formed are not required, but the back zinc layer 13 is preferably formed in order to ensure appropriate rust resistance. Usually, when the zinc layer 12 is formed by the above plating method, the back surface zinc layer 13 is also formed at the same time. However, since the back zinc layer 13 is not required to have the same physical properties as the zinc layer 12, it is not an essential component of the present invention.

  In addition to the above-described layers, the conductive substrate 10 may further include other function enhancement layers as necessary. Examples of these functional enhancement layers include, but are not limited to, a heat resistant layer in which nickel or the like is laminated or an adhesion improving layer using a silane coupling agent or the like provided on the roughened surface. However, in the case where the functional enhancement layer is provided on the surface on the zinc layer 12 side, it is preferable that the layer does not contain chromium in order to avoid adverse effects on soldering suitability.

  In addition, about the surface on the opposite side to the zinc layer 12 used as a joint surface with a resin base material, in order to improve adhesiveness with a resin base material, for example, the adhesion improvement layer using a silane coupling agent etc. It is preferable to separately form a roughening treatment layer in which various roughening particles are laminated. For these layers, it is not necessary to consider the influence on the solderability, so that the exclusion of chromium is not particularly required.

<Current collector sheet for solar cell>
First, the solar cell current collector sheet 1 which is an embodiment of the conductive substrate 10 for forming the wiring pattern of the solar cell current collector sheet of the present invention will be described with reference to FIG. 2A and 2B are schematic views of the solar cell current collector sheet 1. FIG. 2A is a plan view, and FIG. 2B is a longitudinal sectional view taken along line AA in FIG. The conductive substrate 10 of the present invention is used as a material for forming the wiring pattern 10a in the solar cell collector sheet 2 shown in FIG.

  As shown in FIGS. 1A and 1B, the solar cell current collector sheet 1 is obtained by forming a wiring pattern 10 a made of a conductive base material 10 on the surface of a resin base material 20. As will be described in detail later, the wiring pattern 10a is formed on the surface of the resin base material 20 by a method of bonding the conductive base material 10 of the present invention to the surface of the resin base material 20 and then patterning by an etching process or the like. Can do.

  The wiring pattern 10a is an electric wiring formed on the surface of the solar cell current collector sheet 1 so as to have a desired wiring shape (wiring pattern). The wiring pattern 10a includes a conductive layer 11a and a rust prevention protective layer 12b formed on one surface of the conductive layer top 11a.

  The conductive layer 11a is made of copper foil 11 having high conductivity, imparts conductivity to the wiring pattern 10a, is joined to the electrode of the solar cell element on the solar cell current collector sheet, and collects current from the solar cell element. It becomes electric wiring for performing.

  The rust prevention protective layer 12b is a layer made of the zinc layer 12 and suppressing oxidation of the surface of the conductive layer 11a. The rust prevention protective layer 12b is a surface on the side to be joined to the output electrode of the solar cell element in the wiring pattern 10a of the solar cell current collector sheet.

  The back surface antirust protective layer 13a is a antirust layer formed by the back surface zinc layer 13, and is formed on the surface of the conductive layer 11a on the side bonded to the resin base material.

  The resin base material 20 is a resin molded into a sheet shape. Examples of the resin constituting the resin base material 20 include polyethylene resin, polypropylene resin, cyclic polyolefin resin, polystyrene resin, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, polyvinyl chloride resin, Fluorine resin, poly (meth) acrylic resin, polycarbonate resin, polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyamide resins such as various nylons, polyimide resins, polyamideimide resins Examples thereof include resins, polyaryl phthalate resins, silicone resins, polysulfone resins, polyphenylene sulfide resins, polyether sulfone resins, polyurethane resins, acetal resins, and cellulose resins.Among these, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyamide-imide resin, polyimide from the viewpoint that good heat resistance in the soldering process can be imparted to the solar cell collector sheet 1. Based resins are preferred, and polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc. are most preferred.

  What is necessary is just to set the thickness of the resin base material 20 suitably according to the intensity | strength, thinness, etc. which are requested | required of the collector sheet 1 for solar cells. Although the thickness of the resin base material 20 is not specifically limited, 20-250 micrometers is mentioned as an example.

<Method for producing solar battery collector sheet>
Next, an embodiment of the method for producing a solar cell current collector sheet of the present invention will be described with reference to FIGS. 2 (a) to 2 (d) are schematic views sequentially showing how a wiring pattern is formed by an embodiment of the method for producing the solar cell current collector sheet 1 of the present invention. In the following description, the description overlapping with the content already described will be omitted, and different portions will be mainly described.

  The solar cell current collector sheet 1 described above is manufactured by the method for manufacturing the solar cell current collector sheet 1 of the present embodiment. In the method for producing a solar cell current collector sheet of this embodiment, as shown in FIG. 3A, the laminate 3 is formed on the surface of the resin substrate 20 by a laminating step of laminating the conductive substrate 10. The solar cell current collector sheet 1 is produced by subjecting the laminate 3 to an etching step and a peeling step. Hereinafter, the lamination process, the etching process, and the peeling process will be described.

[Lamination process]
In order to join the conductive base material 10 of the present invention to the surface of the resin base material 20, a known method can be used without particular limitation. As such a method, a method of adhering the conductive substrate 10 to the surface of the resin substrate 20 with an adhesive may be mentioned. Among these, a method of adhering the conductive substrate 10 to the surface of the resin substrate 20 by a dry laminating method using an adhesive such as urethane, polycarbonate, or epoxy is preferable. At this time, when the copper foil 11 constituting the conductive base material 10 has a glossy surface and a roughened surface, the roughened surface side is bonded to the resin base material.

[Etching process]
In the etching process, the etching mask 14 patterned in the shape of a desired wiring pattern is formed on the surface of the conductive substrate 10 and then an etching process is performed, so that the conductive group in a portion not covered with the etching mask 14 is obtained. This is a step of removing the material 10.

As already described, the laminate 3 used in this step is obtained by laminating the conductive substrate 10 on the surface of the resin substrate 20. A part of the zinc layer 12 made of zinc is removed in a peeling step to be described later to become a rust prevention protective layer 12b. For this reason, the zinc adhesion amount in the zinc layer 12 may be appropriately adjusted according to the conditions of the peeling process, and the zinc adhesion amount in the zinc layer 12 is 20 to 40 mg under the general peeling process conditions. By adjusting within the range of / m ² , the adhesion amount of zinc in the rust prevention protective layer 12b can be more than 0.5 mg / m ² and 20 mg / m ² or less. The battery current collector sheet 1 can be provided with both rust prevention, stability to solar cell elements, and good solderability.

  In this step, as shown in FIG. 2B, first, an etching mask 14 that is patterned in the shape of a desired wiring pattern on the surface of the conductive substrate 10 (that is, the surface of the zinc layer 12) is produced. The etching mask 14 is provided so that the anticorrosion protection layer 12a and the conductive layer 11a, which will become the wiring pattern 10a in the future, are free from corrosion by the etching solution in an etching process described later. That is, the plan view shape of the wiring pattern 10a to be manufactured and the plan view shape of the etching mask 14 are the same. The method for forming such an etching mask 14 is not particularly limited. For example, the etching mask 14 is formed on the surface of the conductive substrate 10 by developing a photoresist or a dry film after exposing the photoresist or dry film through the photomask. Alternatively, the etching mask 14 may be formed on the surface of the conductive substrate 10 by a printing technique such as an inkjet printer.

  The etching mask 14 needs to be able to be stripped with an alkaline stripping solution in a stripping step described later. From such a viewpoint, it is preferable to produce the etching mask 14 using a photoresist or a dry film.

  Next, the etching process in an etching process is demonstrated. As shown in FIG. 2C, this process is a process of removing a portion of the conductive substrate 10 that is not covered with the etching mask 14 with an etching solution. By passing through this treatment, portions other than the portion to be the wiring pattern 10a in the conductive substrate 10 are removed, so that the wiring pattern 10a has a desired shape on the surface of the resin substrate 20. 10a will remain. About the etching liquid used for an etching process, a well-known thing can be especially used without a restriction | limiting.

[Peeling process]
Next, the peeling process will be described. This step is a step of removing the etching mask 14 using an alkaline stripping solution.

By passing through this process, as shown in FIG.2 (d), the etching mask 14 is removed from the surface of the antirust protection layer 12a. At this time, a part of the surface of the rust preventive protective layer 12a is dissolved by an alkaline stripping solution, and the amount of zinc attached is 5 to 15 mg / m ² in a thin film than the original rust preventive protective layer 12a. It becomes the antirust protection layer 12b. That is, the rust prevention protective layer 12b is a layer formed by the rust prevention protection layer 12a existing on the surface of the conductive substrate 10 becoming a thin film. As described above, the presence of the thin anticorrosive protective layer 12b imparts the anticorrosive property and solderability of the conductive layer 11a to the solar cell collector sheet 1.

  Examples of the alkaline stripping solution used in the stripping step include an aqueous solution of caustic soda.

In the method for producing a solar cell current collector sheet of this embodiment, in the peeling step, the etching mask 14 is completely peeled off, while the zinc adhesion amount of the rust prevention protective layer 12b remains at 5 to 15 mg / m ^2. Dissolve in. For this reason, it is necessary to investigate the conditions under which the etching mask 14 can be completely removed and the amount of zinc deposited on the anticorrosive protective layer 12b can be left at 5 to 15 mg / m ² by a manufacturing test. is there. Specifically, the degree of peeling of the etching mask 14 and the degree of remaining of the anticorrosive protective layer 12b vary depending on the type of the peeling liquid, the temperature of the peeling liquid, the concentration of the peeling liquid, the processing time of the peeling process, and the like. In order to meet the above conditions, the conditions for the peeling process are appropriately determined in the manufacturing test. In addition, what is necessary is just to quantify the quantity of the zinc which remain | survives by atomic absorption analysis etc. as already demonstrated about how much the antirust protective layer 12b remains. After the conditions are determined by the manufacturing test, the manufacturing may be performed using the conditions.

As an example, when a conductive substrate 10 having a zinc layer 12 with an adhesion amount (thickness) of 30 mg / m ² and an etching mask 14 with a thickness of 15 μm obtained by photocuring a dry film are used, the temperature is 40 ° C., the concentration By using a 1.5 g / L aqueous caustic soda solution as a stripping solution and performing a dipping treatment for about 1 minute as a stripping step, the etching mask 14 is completely removed, and the adhesion amount (thickness) of the anticorrosive protective layer 12b is: It became about 10 mg / m ² .

  In addition, in the said solar cell current collection sheet | seat of this invention, there exists the outstanding effect that what is called a solder short can be suppressed suitably. That is, the current collector sheet for solar cells of the present invention is excellent in solder wettability, so that there is almost no solder remaining on the insulating portion between the wirings. For this reason, the solar cell current collector sheet of the present invention is suitably used not only for high-density wiring having a pitch between wirings of 1 mm or less, but also for high-density wiring of 200 μm or less or high-density wiring of 100 μm or less.

  Also, the solder used is an alloy / resin composite solder composed of a conductive alloy component and a highly insulating resin component, and this solder was applied to substantially the entire surface of the solar cell current collector sheet. When the solar battery current collector sheet is overlaid and then reflowed and heat bonded to the solar battery current collector sheet, the alloy component is transferred onto the wiring pattern while leaving the solder resin component between the wires. The solar cell current collector sheet of the present invention can be suitably used for a method of phase-separating the resin and joining the wiring pattern with a solder alloy component. That is, in this case, it is necessary to quickly separate the alloy and the resin by reflow. However, the solar cell current collector sheet of the present invention is excellent in the wettability of the wiring pattern portion, so that the transition of the alloy portion occurs quickly.

<Solar cell module>
The solar cell current collector sheet 1 using the conductive base material 10 of the present invention is incorporated into a solar cell module and used as electrical wiring in the module. The surface of the conductive layer 11a in the solar cell collector sheet 1 and the electrode of the solar cell element are joined by soldering via the rust prevention protective layer 12b, whereby the solar cell collector sheet 1 and the solar cell element Are electrically joined to form electrical wiring.

  Here, the electrode of the solar cell element is an electrode for outputting electric power generated by receiving light from the solar cell element to the outside of the solar cell element. Although not particularly limited, this electrode is made of silver or a silver compound as an example.

  As the solder used in the soldering process, a conventionally known solder can be used without any particular limitation. Examples of such solder include lead-tin alloy solder, silver-containing solder, lead-free solder, tin-bismuth, tin-bismuth-silver, and the like. When joining the electrode of the solar cell element and the surface of the copper foil 11 by soldering via the antirust protective layer 12b, a conventionally known method can be used without any particular limitation.

  The joined body of the solar cell current collector sheet 1 and the solar cell element is formed by combining a transparent front substrate, a front surface side sealing material sheet, a back side side sealing material sheet, a back surface protection sheet, and the like as necessary. It becomes a battery module.

  As an example of such a solar cell module, from the surface side of the solar cell module, a transparent front substrate, a front surface side sealing material sheet, a joined body of the solar cell element and the solar cell current collector sheet 1, and a back surface side sealing material The sheet and the back surface protective sheet are stacked in this order and integrated by vacuum heat laminating, but are not limited to such a configuration, and appropriately configured in consideration of the performance required for the solar cell module do it.

  As described above, the conductive substrate for forming the wiring pattern of the solar cell current collector sheet of the present invention and the method for producing the solar cell current collector sheet using the conductive substrate are specifically described with reference to the embodiment and the embodiment. However, the present invention is not limited to the above-described embodiments and embodiments, and can be implemented with appropriate modifications within the scope of the configuration of the present invention.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited to a following example.

<Test Example 1>
Polyethylene naphthalate obtained by molding a conductive base material in which a zinc layer having an adhesion amount of 30 mg / m ² is formed by zinc electrolytic plating on a glossy surface of a copper foil having a thickness of 25 μm obtained by an electrolytic foil method. A laminate obtained by laminating a (PEN) (thickness 50 μm) substrate surface by a dry lamination method was used. Using a dry film on the surface of this laminate, an etching mask having a thickness of 80 μm, a width of 150 mm, and a length of 150 mm was produced.

  Thereafter, using a ferric chloride aqueous solution at a temperature of 45 ° C. and a concentration of 250 g / L as an etching solution, the laminated sheet on which the etching mask was formed was immersed in this etching solution for about 2 minutes, and then washed with pure water. Thereby, the electroconductive base material of the location which is not coat | covered with the etching mask was removed.

  Next, as a peeling step, the laminate subjected to the above etching treatment was immersed in a peeling solution, which is an aqueous caustic soda solution having a temperature of 40 ° C. and a concentration of 1.5 g / L, for the time shown in Table 1. Then, it was washed with pure water. As a result, a wiring pattern having a width of 150 mm and a length of 150 mm made of a conductive base material was formed on the surface of the base material. Table 1 shows the results of quantifying the amount of zinc contained in the anticorrosive protective layer (zinc layer) of the wiring pattern by atomic absorption analysis.

Each of the solar cell current collector sheets of Examples 1 to 3 and Comparative Examples 1 to 2 described in Table 1 was tested for solder adhesion suitability. The solder used in the test contains 42% tin, 57% bismuth, and 1% silver as alloy components (type TCAP-5405, manufactured by Tamura Kaken Co., Ltd.) on the entire surface of the collector sheet for solar cells. After applying the solder, the solar cell current collector sheet was heated and melted on a hot plate so that the solder melting temperature was 160 to 170 ° C. Thereby, the alloy component of solder transferred to the wiring pattern portion of the current collector sheet for solar cells. Solder adhesion suitability was evaluated visually and in accordance with the following criteria.
○: Solder spreads over the wiring pattern and showed good wettability △: Solder adhered to the surface of the wiring pattern so as to rise, but adhesion was good ×: Solder raised to the surface of the wiring pattern Adhered and adhesion was poor

Each of the current collector sheets for solar cells of Examples 1 to 3 and Comparative Examples 1 and 2 described in Table 1 was evaluated for rust prevention by leaving it at 85 ° C. and 85% RH for 24 hours. The evaluation of rust prevention property was performed by visual observation, and the following criteria were followed.
○: No fogging occurs on the surface of the wiring pattern. Δ: Metal gloss on the surface of the wiring pattern is slightly lowered. X: The wiring pattern is partially discolored.

As shown in Table 1, in the solar cell current collector sheets of Examples 1 to 3 in which the amount of zinc contained in the antirust protective layer is 5 to 15 mg / m ² , both solder adhesion suitability and antirust properties are achieved. On the other hand, it can be seen that Comparative Examples 1 and 2 cannot satisfy either the solder adhesion suitability or the rust prevention property. From this, the effectiveness of the solar cell current collector sheet using the conductive substrate of the present invention can be confirmed.

<Test Example 2>
The solar cell current collector sheets of Examples 4 to 7 and Comparative Examples 3 to 4 were obtained in the same manner as in Test Example 1 except that the amount of zinc contained in the anticorrosive protective layer was changed to the amount shown in Table 2 below. Next, solder was applied in a circular shape on each solar cell current collector sheet using a 6 mm diameter screen. Thereafter, the solar cell current collector sheet was heated and melted with a hot plate so that the solder melting temperature was 160 to 170 ° C., and then cooled by being left standing.

  At this time, the solder formed a substantially convex hemisphere (dome shape) in cross-sectional view on the copper surface due to surface tension. This height was measured with a micrometer to obtain the solder height (average value of N = 3). Moreover, the solder coating amount for each spot was measured separately, and the solder height per unit weight was obtained. Further, the visual appearance of wettability was shown in three stages as in Test Example 1. The results are summarized in Table 2. FIG. 4 is a graph showing the relationship between the amount of zinc contained in the anticorrosive protective layer on the horizontal axis and the solder height per unit weight on the vertical axis.

  As shown in Table 2 and FIG. 4, it can be understood that the wettability is good with the amount of zinc within the range of the present invention and within the preferable range. When the amount of zinc was zero (Comparative Example 4), rust was generated on the copper surface at the start of measurement, and evaluation was not performed. For this reason, in Table 2, the wettability visual evaluation is represented as “−”.

  Further, from Table 2 and FIG. 4, it was found that solder was applied in a spot shape and melted and cooled, and the height of the solder was suitable as an indicator of wettability. In addition, when it is difficult to make the coating amount for each spot constant, the accuracy is further improved by measuring the solder coating amount to obtain the solder height per unit weight. In this example, it can be understood that there is a critical point of wettability in the vicinity of 20 mg of zinc (around 10 μm in solder height). By using this method, the wettability can be easily compared only by measuring the height, which is extremely useful as an evaluation method.

<Test Example 3>
The shiny side of a copper foil having a thickness of 25μm obtained by electrolytic steel foil method, coating weight 5mg / zinc layer of m ² and further deposition amount 2 mg / m ² of conductive chromium layer is formed on the upper layer by electroplating The laminated body which laminated | stacked the base material on the surface of the same base material as Test Example 1 by the dry lamination method was used. Using a dry film on the surface of this laminate, an etching mask having a thickness of 80 μm, a width of 150 mm, and a length of 150 mm was prepared as in Test Example 1.

  Then, the electroconductive base material of the location which is not coat | covered with the etching mask on the same method and conditions as the test example 1 was removed.

Next, as a peeling process, the laminate subjected to the etching treatment was immersed in a peeling solution, which is a caustic soda aqueous solution having a temperature of 40 ° C. and a concentration of 1.5 g / L, for 90 seconds as in Example 1. Then, it was washed with pure water. As a result, a wiring pattern having a width of 150 mm and a length of 150 mm made of a conductive base material was formed on the surface of the base material. When the amount of chromium contained in the surface layer of the anticorrosive protective layer of the wiring pattern was quantified by atomic absorption analysis, the amount of chromium deposited was 2 mg / m ² .

  About the solar cell current collector sheet provided with this chromium layer, the solder adhesion suitability and rust prevention property were evaluated by the test method and evaluation criteria described in Test Example 1 above. As a result, the results were ◯ for rust prevention and x for solder adhesion.

DESCRIPTION OF SYMBOLS 1 Current collection sheet | seat for solar cells 10 Conductive base material 10a Wiring pattern 11 Copper foil 11a Conductive layer 12 Zinc layer 12a Rust protection layer 12b Rust protection layer 13 Back surface zinc layer 13a Back surface protection layer 14 Etching mask 20 Resin group Material 3 Laminate

Claims (3)

A conductive substrate used for manufacturing a wiring pattern of a solar cell current collector sheet,
With a thickness of 10 μm to 35 μm and formed of electrolytic foil, the glossy surface of the copper foil provided with a glossy surface and a roughened surface having a relatively large surface roughness than the glossy surface, have been 30 mg / ^{m 2} or less of the zinc layer is formed beyond the 25 mg / ^{m 2} as adhesion amount,
The electroconductive base material which does not contain chromium in any layer currently formed in the said glossy surface side of the said copper foil . The conductive base material according to claim 1, wherein a functional enhancement layer not containing one or more chromium is further formed on the zinc layer formed on the glossy surface of the copper foil. On at least one surface of a copper foil having a thickness of 10Myuemu～35myuemu, beyond 25 mg / ^{m 2} a conductive substrate 30 mg / ^{m 2} or less of the zinc layer is formed, the zinc layer is formed as a coating weight A laminating step of obtaining a laminate by laminating the resin substrate with the surface opposite to the surface being a bonding surface with the resin substrate;
By performing an etching process after forming an etching mask patterned in the shape of a desired wiring pattern on the surface of the stacked body, the conductive substrate in a portion not covered with the etching mask is removed, and the wiring pattern An etching process to form
A stripping step of removing the etching mask using an alkaline stripping solution after the etching step, and a method for producing a solar cell current collector sheet,
In the stripping step, the etching mask is stripped and a part of the surface of the zinc layer is removed with the alkaline stripping solution, so that the amount of zinc deposited exceeds 0.5 mg / m ² and 5 mg / m ^2. The manufacturing method of the current collection sheet | seat for solar cells characterized by forming the antirust protection layer which is m < ² > or less on the surface of the said wiring pattern.

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