JP2011129858A - Wiring sheet, solar cell modules, and manufacturing methods thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring sheet which has good rust prevention and solderability without the use of organic anticorrosives which may have a bad influence on a solar cell, and also to provide its manufacturing method. <P>SOLUTION: A wiring sheet 1 has a conductive layer 4 made of copper and laminated on the surface of resin substrate 2 and an anticorrosive protection layer 5 made of zinc and formed on the surface of the conductive layer 4 by thin-film formation, wherein the amount of zinc is >0.5 mg/m<SP>2</SP>and ≤20 mg/m<SP>2</SP>. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a resin-based wiring sheet and a method for manufacturing the same, and more particularly to a wiring sheet used as a wiring in a solar cell module and a method for manufacturing the same.

  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 includes a transparent front substrate, a front surface side filler sheet, a solar cell, a back surface side filler sheet, and a back sheet (also referred to as a back surface protection sheet) from the light receiving surface side. It is the structure laminated | stacked in order and has the function to generate electric power when sunlight injects into the said photovoltaic cell.

  A plurality of solar cells 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 cells inside a solar cell module, for example, a wiring sheet in which a metal foil that becomes a wiring pattern is laminated on the surface of a resin sheet as a base material is used (see Patent Document 1). ). And the metal foil which is the wiring provided in the wiring sheet, and the output electrode of a photovoltaic cell are electrically joined by soldering.

  In order to provide wiring on the surface of the resin sheet that is the base material of the wiring sheet, for example, similarly to a printed wiring board, first, a metal foil is laminated on the entire surface of the base material, and then this metal foil is photolithography. Etching may be performed so as to obtain a desired wiring pattern by a method.

  By the way, the surface of the copper foil 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 which is a wiring pattern needs rust prevention processing. In this respect, in a printed wiring board, a method of applying a rust-preventive coating on the surface of the wiring pattern (see Patent Document 2), and a method of forming a film having a complex structure with copper on the surface of the wiring pattern (Patent Document 3) In general, an organic rust prevention treatment is applied to the surface of the wiring pattern as in The printed wiring board subjected to such rust prevention treatment suppresses the oxidation of the surface of the wiring pattern and maintains good wettability with respect to the solder. This is preferable from the viewpoint of secure mounting.

JP 2007-081237 A Japanese Patent Laid-Open No. 9-326549 JP-A-6-6018

  As for the wiring sheet used in the solar cell module, the wiring pattern on the wiring sheet is oxidized between the time when the wiring sheet is manufactured and the time when it is incorporated into the solar cell module, as in the case of the printed wiring board. It is necessary to prevent this. However, since the wiring sheet for solar cell modules is used in a state of being bonded to the solar cells, the wiring sheet is subjected to a rust prevention treatment using an organic rust preventive agent like a printed wiring board. Then, during use as a solar cell module for a long period of time, the rust preventive agent contained in the wiring sheet may adversely affect the solar cells and cause the performance deterioration of the solar cell modules.

  In addition, it is conceivable to carry out rust prevention treatment by applying zinc / chrome plating or galvanization to the copper foil on the wiring sheet, but in this case, as in the case of using an organic rust inhibitor. While the adverse effect on the solar cell is reduced, the wettability of the wiring pattern with respect to the solder is remarkably lowered, and there is a problem that the reliability of the joining between the solar cell and the wiring sheet by the solder is lowered.

  As described above, there is no wiring sheet that can achieve both stability to solar cells and good solderability (that is, wettability to solder).

  The present invention has been made in view of the above situation, and has good rust prevention and solderability without using an organic rust inhibitor that may adversely affect solar cells. It is an object of the present invention to provide a wiring sheet including the above and a manufacturing method thereof.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the presence of a very thin zinc plating of several atoms level as a protective film on the surface of the copper foil as a wiring pattern is good. As a result, the inventors have found that both rust prevention and solderability can be achieved, and have completed the present invention.

(1) The present invention is a wiring sheet in which a conductive layer made of copper is laminated on the surface of a resin base material, and a rust preventive protective layer made of zinc is formed in a thin film on the surface of the conductive layer, a wiring sheet, wherein the amount of said zinc is 20 mg / ^{m 2} or less beyond the 0.5 mg / ^{m 2.}

(2) According to the present invention, the amount of the zinc is a wiring sheet is 10 mg / ^{m 2} or less beyond the 0.5 mg / ^{m 2} (1) above, wherein.

(3) According to the present invention, the amount of said zinc is 6 mg / ^{m 2} or less beyond the 0.5 mg / ^{m 2} (1) or (2) a wiring sheet according to claim.

  (4) The present invention is the wiring sheet according to any one of (1) to (3), wherein the wiring sheet is for internal wiring in a solar cell module.

  (5) Moreover, this invention is a solar cell module characterized by joining the surface of the electrically conductive layer in the wiring sheet | seat of the (4) term, and the electrode of a photovoltaic cell by soldering.

(6) In the present invention, a laminated sheet in which a conductive layer made of copper and a plated layer made of zinc are sequentially laminated on the surface of a resin base material is patterned into a desired wiring pattern shape. An etching process for removing the plating layer and the conductive layer in a portion not covered with the etching mask by performing an etching process after producing an etching mask on the surface of the laminated sheet, and then using an alkaline stripping solution And a peeling step of removing the etching mask, and in the peeling step, at the same time that the etching mask is peeled off, a part of the surface of the plating layer is made alkaline. is removed by stripping solution, the density of a thin film than the original plating layer exceeds the 0.5mg / ^{m 2} 20mg / ^{m 2} A method of manufacturing a wiring sheet, characterized in that to form a rust protective layer is below the surface of the conductive layer.

  (7) Moreover, this invention includes the process of joining the surface of the electrically conductive layer in the wiring sheet manufactured by the manufacturing method of (6) description, and the electrode of a photovoltaic cell by soldering. It is a manufacturing method of a solar cell module.

(8) The present invention, by forming a 20 mg / m ² or less of zinc film beyond 0.5 mg / m ² on the copper surface, the copper surface to improve solder adhesion suitability and corrosion resistance of the copper surface This is a surface treatment method.

  (9) Further, in the present invention, after a predetermined amount of solder is applied to the copper surface in a spot shape, the copper is heated at a predetermined temperature to melt and adhere the solder to the copper surface, and then the height of the solder is increased. This is a solder wettability evaluation method in which the height is measured and the height is used as an index of wettability.

  (10) Further, the present invention is the solder wettability evaluation method according to (9), wherein the solder coating amount per spot is measured, and the height of the solder per unit mass of the solder is used as the index. .

  ADVANTAGE OF THE INVENTION According to this invention, the wiring sheet provided with favorable rust prevention property and solderability, and its manufacturing method are provided, without using the organic type rust preventive agent which may have a bad influence on a photovoltaic cell. The

It is a schematic diagram which shows one Embodiment of the wiring sheet of this invention, (a) is a top view, (b) is a longitudinal cross-sectional view in the AA of (a). (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 perspective view which shows typically a mode that the wiring sheet of this invention is joined to a photovoltaic cell. It is a graph which shows the relationship between the surface zinc amount in Example 2, and solder height.

  Hereinafter, one embodiment of the wiring sheet of the present invention, one embodiment of the manufacturing method of the wiring sheet of the present invention, one embodiment of the solar cell module of the present invention, and one embodiment of the manufacturing method of the solar cell module of the present invention Will be described.

<One Embodiment of the Wiring Sheet of the Present Invention>
First, an embodiment of the solar cell module of the present invention will be described with reference to FIG. 1A and 1B are schematic views showing an embodiment of a wiring sheet of the present invention, in which FIG. 1A is a plan view and FIG. 1B is a longitudinal sectional view taken along line AA in FIG.

  The wiring sheet 1 of this embodiment is manufactured by one embodiment of the method for manufacturing a wiring sheet of the present invention described later. The wiring sheet 1 has a wiring pattern 3 formed on the surface of a resin base material 2.

  The resin base material 2 is a resin molded into a sheet shape. Here, the sheet form is a concept including a film form, and there is no difference between them in the present invention. Examples of the resin constituting the resin substrate 2 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), polyamideimide resin, polyimide resin, and the like are preferable from the viewpoint that good heat resistance in soldering can be imparted to the wiring sheet 1. Polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc. are most preferable.

  What is necessary is just to set the thickness of the resin base material 2 suitably according to the intensity | strength, thinness, etc. which are requested | required of the wiring sheet 1. FIG. Although the thickness of the resin base material 2 is not specifically limited, 20-250 micrometers is mentioned as an example.

  The wiring pattern 3 is an electrical wiring formed on the surface of the wiring sheet 1 so as to have a desired wiring shape (wiring pattern). The wiring pattern 3 includes a conductive layer 4 and a rust prevention protective layer 5. Next, these layers will be described.

  The conductive layer 4 is a layer for imparting conductivity to the wiring pattern 3 and is a layer made of copper. In order to form the conductive layer 4 on the surface of the resin base material 2, a method of bonding a copper foil to the surface of the resin base material 2 and then patterning the copper foil by etching or the like is exemplified. In order to join the copper foil to the surface of the resin base material 2, a known method can be used without particular limitation. Examples of such a method include a method of adhering copper foil to the surface of the resin base material 2 with an adhesive, a method of depositing copper on the surface of the resin base material 2, and the like from the viewpoint of cost. A method of adhering the foil to the surface of the resin substrate 2 with an adhesive is advantageous. Among these, a method of adhering the copper foil to the surface of the resin base material 2 by a dry laminating method using an adhesive such as urethane, polycarbonate, or epoxy is preferable.

  What is necessary is just to set the thickness of the conductive layer 4 according to the magnitude | size of the electric current resistance requested | required of the wiring sheet 1, etc. suitably. Although the thickness of the conductive layer 4 is not specifically limited, As an example, 10-35 micrometers is mentioned.

  Next, the rust prevention protective layer 5 will be described. The rust prevention protective layer 5 is a layer provided to suppress oxidation of the copper surface constituting the conductive layer 4, and is a zinc layer formed as a thin film on the surface of the conductive layer 4.

The amount of zinc forming the anticorrosive protective layer 5, 20 mg / ^{m 2} or less beyond the 0.5 mg / ^{m 2} As apparent from Examples to be described later, preferably not exceed 0.5mg / ^{m 2} 10mg / m ² or less, more preferably 6 mg / ^{m 2} or less beyond the 0.5 mg / ^{m 2.} This amount is very small to form a layer (thin film). Therefore, a thin film formed of such an amount of zinc is considered to have a thickness of several atoms, and it is considered that defects of the film are generated in some places. It is considered that the copper of the conductive layer 4 existing under the rust preventive protective layer 5 is exposed in some places because of such film defects. By having such a configuration, the wiring sheet 1 of the present invention is thought to be compatible with both solder adhesion suitability and rust prevention of copper as the conductive layer 4.

  This will be described in more detail. As described in the background section, the surface of copper is very easily oxidized. Therefore, in a printed wiring board or the like, in order to prevent the surface of the copper wiring from being oxidized, after the copper wiring is produced, the surface is subjected to rust prevention treatment. This rust preventive treatment uses an organic rust preventive and is devised so as not to affect the solder adhesion on the copper wiring surface. For this reason, in the printed wiring board, it is possible to achieve both rust prevention of copper wiring and solder adhesion.

  However, the wiring sheet 1 used as the internal wiring of the solar cell module is different from the printed wiring board. This is because the solar cell module is exposed to sunlight for a long period of several decades, so that the members used for the solar cell module are highly required to be stable against high temperatures and ultraviolet rays. That is, when an organic rust inhibitor is placed in such a harsh environment, the solar cell may be adversely affected by itself or a compound produced by decomposition thereof. Solar cells affected by organic rust inhibitors may be defective or power generation efficiency may be reduced. Therefore, if organic rust inhibitors are used for wiring sheet 1, the lifetime of the solar cell module is reduced. It may lead to a decrease.

  For this reason, in the wiring sheet 1 used as internal wiring of a solar cell module, the rust prevention process which does not use an organic type rust preventive agent is needed. As such a rust prevention treatment, a rust prevention treatment by plating can be considered. In this respect, since the copper foil is usually rust-proofed by chromium / zinc plating or galvanization, the wiring sheet 1 can be protected against by forming the wiring sheet 1 without peeling off the protective plating. It is thought that rustability can be imparted. However, chromium / zinc plating and galvanization are significantly inferior in adhesion to solder compared to the copper surface. Therefore, when the wiring sheet 1 having such a plating is used, not only the soldering process becomes extremely difficult but also the reliability of the wiring in a long-term use is lowered. Thus, in the wiring sheet 1 used for a solar cell module, it is the actual situation that it was difficult to achieve both solder adhesion suitability and rust prevention.

In this respect, in the present invention, as described above, the compatibility of solder adhesion and the antirust property are achieved by forming the antirust protective layer 5 made of zinc on the surface of the conductive layer 4 as a thin film. As already mentioned, zinc has poor adhesion to solder. However, the present inventors have surprisingly found that the amount of zinc contained in the rust prevention protective layer 5 (zinc layer) formed on the surface of the conductive layer 4 exceeds 0.5 mg / m ² and is 20 mg / m ^2. It has been found that by making the following, the decrease in the solder adhesion suitability due to zinc is suppressed, and the oxidation of copper constituting the conductive layer 4 is suppressed. The present invention has been completed based on such findings.

As already mentioned, in the present embodiment, the amount of zinc contained in the anticorrosive protective layer 5 to be formed on the surface of the conductive layer 4 is 10 mg / m ² or less beyond the 0.5 mg / m ^2. When the amount of zinc contained in the rust prevention protective layer 5 is 0.5 mg / m ² or less, a sufficient rust prevention effect for the conductive layer 4 cannot be obtained. On the other hand, if the amount of zinc contained in the rust prevention protective layer 5 exceeds 20 mg / m ² , the adhesion of the wiring pattern 3 to the solder deteriorates.

  In the wiring sheet 1 of the present embodiment, the amount of zinc contained in the rust prevention protective layer 5 is extremely small as described above. In order to quantify such a small amount of zinc, the rust prevention protective layer 5 whose area is known in advance is dissolved with an acid or alkali, and the amount of zinc atoms contained in the obtained solution is determined by atomic absorption analysis. Good.

<One Embodiment of Manufacturing Method of Wiring Sheet of the Present Invention>
Next, an embodiment of the method for manufacturing a wiring 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 manufacturing a wiring sheet 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 wiring sheet 1 demonstrated above is manufactured by the manufacturing method of the wiring sheet of this embodiment. In the method for manufacturing a wiring sheet according to this embodiment, as shown in FIG. 2A, a conductive layer 4 made of copper and a plating layer 6 made of zinc are sequentially laminated on the surface of the resin base 2. A laminated sheet 9 is used. The wiring sheet 1 is produced by performing an etching process and a peeling process on the laminated sheet 9. Hereinafter, the etching process and the peeling process will be described.

[Etching process]
First, the etching process will be described. In this step, the etching mask 7 patterned in the shape of a desired wiring pattern is formed on the surface of the laminated sheet 9 and then an etching process is performed, so that the plating layer 6 and the conductive layer in the portion not covered with the etching mask 7 are processed. This is a step of removing the layer 4.

As already described, the laminated sheet 9 used in this step is such that the conductive layer 4 made of copper and the plated layer 6 made of zinc are sequentially formed on the surface of the resin base material 2. The method for forming the conductive layer 4 made of copper on the surface of the resin base 2 is as already described. In order to form the plating layer 6 made of zinc on the surface of the conductive layer 4, a known plating method may be used. A part of the plating layer 6 made of zinc is removed in a peeling step described later. For this reason, what is necessary is just to adjust the thickness of the plating layer 6 suitably according to the conditions of a peeling process, etc. As an example, the thickness (density) of the plating layer 6 is 20 to 40 mg / m ² .

  In this step, as shown in FIG. 2B, first, an etching mask 7 patterned in the shape of a desired wiring pattern is produced on the surface of the laminated sheet 9 (that is, the surface of the plating layer 6). The etching mask 7 is provided in order to avoid corrosion of the plating layer 6 and the conductive layer 4 to be the wiring pattern 3 in the future in the etching process described later. That is, the plan view shape of the wiring pattern 3 to be manufactured and the plan view shape of the etching mask 7 are the same. A method for forming such an etching mask 7 is not particularly limited. For example, the etching mask 7 may be formed on the surface of the laminated sheet 9 by developing a photoresist or a dry film after exposure through the photomask. Alternatively, the etching mask 7 may be formed on the surface of the laminated sheet 9 by a printing technique such as an inkjet printer.

  The etching mask 7 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 7 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 the plating layer 6 and the conductive layer 4 in a portion not covered with the etching mask 7 with an etching solution. Through this treatment, portions of the plating layer 6 and the conductive layer 4 other than the portion that becomes the wiring pattern 3 are removed, so that the surface of the resin substrate 2 has a desired shape of the wiring pattern 3. The plating layer 6 and the conductive layer 4 remain. About the etching liquid used for an etching process, a well-known thing can be especially used without a restriction | limiting. In the etching process, the plating layer 6 and the conductive layer 4 may be removed by a single process, or the process of removing the conductive layer 4 after the process of removing the plating layer 6 may be performed a plurality of times. Processing may be performed.

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

Through this step, the etching mask 7 is removed from the surface of the plating layer 6 as shown in FIG. At this time, a part of the surface of the plating layer 6 is dissolved by an alkaline stripping solution, and is a thin film than the original plating layer 6 and the density thereof is 5 to 15 mg / m ^2. Become. That is, the rust prevention protective layer 5 is a layer formed by the plating layer 6 existing on the surface of the laminated sheet 9 becoming a thin film. As described above, the presence of the thin anticorrosive protective layer 5 gives the wiring sheet 1 the anticorrosive properties and the solder adhesion suitability of the conductive layer 4.

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

In the method for manufacturing a wiring sheet of this embodiment, in the peeling step, the etching mask 7 is completely peeled off, while the plating layer 6 is dissolved so as to remain at a density (thickness) of 5 to 15 mg / m ² . The remaining plating layer 6 becomes the rust prevention protective layer 5. For this reason, it is necessary to investigate the conditions under which the etching mask 7 can be completely removed and the plating layer 6 can be left at a density (thickness) of 5 to 15 mg / m ² by a manufacturing test. . Specifically, the degree of peeling of the etching mask 7 and the remaining degree of the plating layer 6 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 conditions, the conditions for the peeling process are appropriately determined in the manufacturing test. As to how much the plating layer 6 remains, the amount of remaining zinc may be quantified by atomic absorption analysis or the like as already described. After the conditions are determined by the manufacturing test, the manufacturing may be performed using the conditions.

As an example, when a sheet having a plating layer 6 having a density (thickness) of 30 mg / m ² and having an etching mask 7 having a thickness of 15 μm obtained by photocuring a dry film is used, the temperature is 40 ° C. and the concentration is 1.5 g. Etching mask 7 is completely removed by using a / L aqueous caustic soda solution as a stripping solution, and performing a dip treatment for about 1 minute as a stripping step, and the density (thickness) of plating layer 6 (rust prevention protective layer 5) is About 10 mg / m ² .

  In addition, in the wiring sheet of the present invention described above, there is an excellent effect that so-called solder shorts can be suitably suppressed. That is, since the wiring sheet of the present invention has excellent solder wettability, there is almost no solder remaining on the insulating portion between the wirings. For this reason, especially the wiring sheet of this invention is used suitably not only in the high density wiring whose wiring pitch is 1 mm or less, but also in the high density wiring of 200 μm or less and the high density wiring of 100 μm or less.

  Also, the solder to be used is an alloy / resin composite solder composed of a conductive alloy component and a highly insulating resin component, and after the solder is applied to substantially the entire surface of the wiring sheet, Overlap, and then reflow and heat-bonding to the wiring sheet, leaving the solder resin component between the wires, the alloy component is transferred onto the wiring pattern to phase separate the alloy and the resin, the solder alloy component The wiring sheet of this invention can be used suitably for the method of joining with a wiring pattern. That is, in this case, it is necessary to quickly separate the alloy and the resin by reflow. However, since the wiring sheet of the present invention is excellent in the wettability of the wiring pattern portion, the migration of the alloy portion occurs quickly.

<Solar cell module and manufacturing method of solar cell module>
The solar cell module using the wiring sheet 1 as described above and the method for manufacturing the solar cell module are also one aspect of the present invention. Next, one embodiment and one embodiment of these inventions will be described with reference to FIG. FIG. 3 is a perspective view schematically showing how the wiring sheet 1 of the present invention is bonded to the solar battery cell 8.

  In one embodiment of the solar cell module of the present invention, the surface of the conductive layer 4 in the wiring sheet 1 and the electrode of the solar cell 8 are joined by soldering via the antirust protective layer 5. And Specifically, the wiring pattern 3 composed of the conductive layer 4 and the rust prevention protective layer 5 is joined to the electrode (not shown) of the solar battery cell 8 by soldering. Thereby, the wiring sheet 1 and the photovoltaic cell 8 are electrically joined, and become an electrical wiring inside the solar cell module. In addition to the wiring by the wiring sheet 1, in the solar cell module, wiring by a ribbon line or the like may be performed as necessary.

  Here, the electrode of the solar battery cell 8 is an electrode for outputting the electric power generated by the solar battery cell 8 by receiving light to the outside of the solar battery cell 8. Although not particularly limited, this electrode is made of silver or a silver compound as an example.

  Moreover, the conventionally well-known thing can be especially used for a solder used in soldering processing without a restriction. 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 photovoltaic cell 8 and the surface of the conductive layer 4 by soldering via the antirust protective layer 5, a conventionally known method can be used without any particular limitation.

  The joined body of the wiring sheet 1 and the solar battery cell 8 includes, as necessary, a transparent front substrate (not shown), a front side filler sheet (not shown), a back side filler sheet (not shown), A solar cell module is obtained by combining a back sheet (not shown) and the like.

  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 filler sheet, a joined body of the solar cell 8 and the wiring sheet 1, a back surface side filler material sheet, and a back sheet. Although it is possible to superimpose in this order and integrate by vacuum heat laminating, it is not limited to such a configuration, and may be appropriately configured in consideration of the performance required for the solar cell module.

<Surface treatment method>
A surface treatment method for a copper surface that maintains rust prevention and improves solder adhesion on the copper surface by forming a zinc thin film of 0.5 to 20 mg / m ² on the copper surface is also one aspect of the present invention. is there. Since the method of forming a zinc thin film of 5 to 15 mg / m ^{2 on} the copper surface and the effect of applying such a treatment are as described above, the description thereof is omitted here.

  The wiring sheet, the manufacturing method of the wiring sheet, the solar cell module, the manufacturing method of the solar cell module, and the surface treatment method of the present invention have been specifically described with reference to the embodiment and the embodiment. The present invention is not limited to the embodiment and the embodiment, and can be implemented with appropriate modifications within the scope of the configuration of the present invention.

  For example, in the above embodiment and embodiment, the plating layer 6 is formed by galvanization, but may be formed by sputtering or vapor deposition of zinc.

  Moreover, in the said embodiment and embodiment, although the wiring sheet 1 was a wiring sheet for internal wiring in a solar cell module, uses other than a solar cell module may be sufficient. Since the wiring sheet of the present invention achieves both rust prevention properties and solder adhesion suitability without performing organic rust prevention processing, it is suitably used in applications where it is not preferable to perform organic rust prevention processing.

  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>
A 25 μm copper foil is laminated on the surface of polyethylene naphthalate (PEN) (thickness 50 μm) formed into a sheet by a dry laminating method, and a plating layer having a density of 30 mg / m ² by galvanization is further formed on the surface of this copper foil. Was used as a resin base material (a copper foil generally used for printed circuit boards). Using a dry film on the surface of this resin substrate, 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 plating layer and copper foil of the location which is not coat | covered with the etching mask were removed.

  Next, as a peeling step, the laminated sheet that had undergone the above etching treatment was immersed in a peeling solution that was an aqueous caustic soda solution at 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 in which a conductive layer made of copper foil and a rust-preventing protective layer made of zinc were formed was formed on the surface of the substrate. Table 1 shows the results of quantitative determination of the amount of zinc contained in the rust prevention protective layer by atomic absorption analysis.

Each of the wiring sheets of Examples 1 to 3 and Comparative Examples 1 and 2 described in Table 1 was tested for solder adhesion suitability. The solder used for the test contains 42% tin, 57% bismuth and 1% silver as alloy components (type TCAP-5405 manufactured by Tamura Kaken Co., Ltd.), and the solder was applied to the entire surface of the wiring sheet. Thereafter, the wiring sheet was heated and melted with 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 wiring sheet. 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 swell, but adhesion was good ×: Solder swelled on the surface of the wiring pattern Adhered and adhesion was poor

Each of the wiring sheets 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 wiring sheets of Examples 1 to 3 in which the amount of zinc contained in the rust prevention protective layer is 5 to 15 mg / m ² , both solder adhesion suitability and rust prevention can be achieved. On the other hand, in Comparative Examples 1 and 2, it can be seen that either solder adhesion suitability or rust prevention property cannot be satisfied. From this, the effectiveness of the wiring sheet of this invention can be confirmed.

<Test Example 2>
Wiring 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 wiring sheet using a 6 mm diameter screen. Thereafter, the wiring sheet was heated and melted with a hot plate so that the solder melting temperature was 160 to 170 ° C., and then cooled by 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.

DESCRIPTION OF SYMBOLS 1 Wiring sheet 2 Resin base material 3 Wiring pattern 4 Conductive layer 5 Antirust protection layer 6 Plating layer 7 Etching mask 8 Solar cell 9 Laminated sheet

Claims (10)

A wiring sheet in which a conductive layer made of copper is laminated on the surface of a resin base material,
On the surface of the conductive layer, a rust prevention protective layer made of zinc is formed as a thin film,
Wiring sheet, wherein the amount of said zinc is 20 mg / ^{m 2} or less beyond the 0.5 mg / ^{m 2.} Wiring sheet of claim 1 wherein the amount of said zinc is 10 mg / ^{m 2} or less beyond the 0.5 mg / ^{m 2.} Wiring sheet according to claim 1 or 2 wherein the amount of said zinc is 6 mg / ^{m 2} or less beyond the 0.5 mg / ^{m 2.}   The wiring sheet according to claim 1, wherein the wiring sheet is for internal wiring in a solar cell module.   The solar cell module, wherein the surface of the conductive layer in the wiring sheet according to claim 4 and the electrode of the solar cell are joined by soldering. Using a laminated sheet in which a conductive layer made of copper and a plated layer made of zinc are sequentially laminated on the surface of the resin base material,
An etching process for removing a plating layer and a conductive layer in a portion not covered with the etching mask by performing an etching process after producing an etching mask patterned in the shape of a desired wiring pattern on the surface of the laminated sheet When,
Next, a peeling step of removing the etching mask using an alkaline stripping solution, and a method for manufacturing a wiring sheet comprising:
In the stripping step, at the same time as stripping the etching mask, a part of the surface of the plating layer is removed with the alkaline stripping solution, so that the density is 0.5 mg as a thin film than the original plating layer. method for manufacturing a wiring sheet, wherein the / m ² and over to form a rust protective layer is 20 mg / m ² or less on the surface of the conductive layer.   A method for manufacturing a solar cell module, comprising a step of joining a surface of a conductive layer in a wiring sheet manufactured by the manufacturing method according to claim 6 and an electrode of a solar cell cell by soldering. By forming a 20 mg / m ² or less of zinc film beyond 0.5 mg / m ² on the copper surface, the surface treatment method of the copper surface to improve solder adhesion suitability and corrosion resistance of the copper surface.   After a predetermined amount of solder is applied to the copper surface in a spot shape, the copper is heated at a predetermined temperature to melt and adhere the solder to the copper surface, and then the height of the solder is measured. Solder wettability evaluation method using as a measure of wettability.   The solder wettability evaluation method according to claim 9, wherein the solder coating amount per spot is measured, and the height of the solder per unit mass of the solder is used as the index.

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