JP2016072552A - Circuit board, manufacturing method thereof, and solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a circuit board which eliminates the need for the step of removing an unwanted part in circuit pattern formation and reduces the occurrence of a trouble owing to burr of an end face of a circuit pattern and the delamination of a circuit pattern; and a method for manufacturing such a circuit board.SOLUTION: A circuit board comprises a base material 53, an adhesion layer 52 and metal electrode patterns 51a and 51b which are laminated in turn. The metal electrode patterns 51a and 51b have short-circuit prevention layers 54a and 54b made of an oxide of a metal constituting metal electrodes in their end face parts respectively. The metal electrodes are made of one of aluminum, copper, iron or an alloy thereof.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a solar cell circuit board, and more particularly to a structure for improving insulation between wiring circuits and a method for manufacturing the same.

  Conventionally, when a conductive pattern such as a circuit or wiring is formed on a substrate, a metal thin film is formed on the substrate and then patterned by photoetching, etc., and unnecessary metal thin film is removed to remove the conductive film. In many cases, a sex pattern is formed.

  Since such a manufacturing method requires many steps, in recent years, a conductive pattern is formed by bonding a metal foil sheet on a substrate and punching the metal foil with a punching blade. For example, in Patent Document 1, in order to form an antenna pattern of an IC tag, a metal foil sheet having an adhesive layer and a supporting base material are overlapped, and the metal foil sheet is punched and temporarily used with a heated punching blade. A technique is disclosed in which a conductive pattern serving as an antenna is formed by stopping and removing unnecessary portions with a suction machine or the like.

JP 2007-76288 A

However, the prior art punching has the following problems.
When forming a circuit pattern, an unnecessary portion removing process is required after the metal foil is punched into a pattern. However, if the pattern of this unnecessary portion becomes complicated, it will be broken at the time of peeling, making the removal operation difficult. In addition, when removing unnecessary parts, the edge part of the required circuit pattern is pulled, burrs appear on the circuit end face, and the circuit pattern floats or peels off. There was a problem.

  Further, when forming a circuit pattern by a conventional method, punching is performed with two parallel parallel blades, and unnecessary portions are peeled off. However, if the interval is 1 mm or less, it becomes a limit of physical proximity by an unnecessary portion of the punching blade, and it becomes difficult to form a high-density wiring pattern because pattern punching becomes difficult. On the other hand, when a single blade is simply punched, there is a problem that there is no distance between circuit patterns and a short circuit due to contact occurs, and the circuit is not established.

  The present invention has been made in view of the above circumstances, and provides a circuit board that eliminates the need to remove unnecessary portions when forming a circuit pattern, and reduces defects due to circuit pattern end surface burrs and circuit pattern peeling, and a method of manufacturing the circuit board. The present invention provides a high-density circuit board and a solar cell module that are inexpensive and highly reliable.

The first aspect of the present invention is:
In a circuit board in which a base material, an adhesive layer, and a metal electrode are sequentially laminated,
The circuit board is characterized in that an end face portion of the metal electrode is provided with a short-circuit prevention layer made of a metal oxide composing the metal electrode.

The second aspect of the present invention is:
A step of sequentially laminating a base material, an adhesive layer, and a metal foil;
Cutting the metal foil by punching to form a metal electrode pattern;
The method for manufacturing a circuit board according to claim 1, further comprising: oxidizing the end face of the metal electrode pattern to form a short-circuit prevention layer.

  According to a third aspect of the present invention, in the method for manufacturing a circuit board according to claim 2, the metal electrode is aluminum, copper, iron, or an alloy thereof. is there.

  According to a fourth aspect of the present invention, there is provided a solar cell module comprising the circuit board according to claim 1.

According to the circuit board of the present invention, it is not necessary to remove unnecessary portions when forming a circuit pattern. In addition, defects such as edge burrs in the conductive circuit are reduced, and in addition, since the end face is covered with an insulating layer, it is possible to reduce a short circuit between wirings even if the circuit is miniaturized.
Therefore, it is possible to provide a high-quality circuit board, and by applying this circuit board, it is possible to provide an inexpensive and highly reliable solar cell module.

It is a figure of typical sectional view showing the composition of the solar cell module of one embodiment of the present invention. It is process drawing of the cross-sectional view explaining the punching process of a circuit board. It is process drawing of the cross sectional view explaining a mode that an insulating layer and a protective layer are formed in the end surface of a circuit board. It is process drawing of the cross sectional view explaining an example of the manufacturing process of a solar cell module. FIG. 5 is a cross-sectional process diagram illustrating an example of a manufacturing process of a solar cell module, and is a continuation of FIG. 4.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 5. In all the drawings, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.
FIG. 1 is a schematic cross-sectional view showing the configuration of the solar cell module 60.

As shown in FIG. 1, the solar cell module 60 of the present embodiment has a light receiving surface 20c that receives light for power generation and a back surface 20d on the opposite side, and a connection electrode 20a for wiring on the back surface 20d. Solar cell 20 provided with a plurality of 20b, circuit substrate 50 protecting solar cell 20, and sealing material 30 stacked on circuit substrate 50 and solar cell 20 to seal solar cell 20 And a conductive connecting material 10 electrically connected to the solar battery cell 20 and a translucent substrate 40 laminated on the sealing material 30.
The solar cell module 60 is manufactured using the circuit board for solar cells of the present invention. Details will be described later.

  The solar battery cell 20 is a semiconductor element that generates electricity by photoelectrically converting light incident from the light receiving surface 20c. The solar cell 20 is not particularly limited as long as it is a so-called back contact type solar cell in which a positive connection electrode 20a and a negative connection electrode 20b are provided on the back surface 20d. Known materials such as crystals and amorphous materials can be appropriately selected.

  Although FIG. 1 is a schematic diagram, the drawing is simplified, but the number of connection electrodes 20a and 20b can be appropriately set to two or more as needed. The connection electrodes 20a and 20b are made of, for example, a baked silver paste. The connection electrodes 20a and 20b may be different in size and shape, but in the following description, the connection electrodes 20a and 20b are described as having the same size and shape as an example.

  As the shape of the solar cell 20 in plan view, for example, a suitable shape such as a rectangular shape can be selected, and there is no particular limitation. Further, only one solar battery cell 20 in the solar battery module 60 is illustrated in FIG. 1, but two or more solar battery cells 20 are arranged along the surface direction of the circuit board 50 with appropriate intervals. Yes. In the present embodiment, although not shown, a plurality of solar cells 20 are aligned and arranged at predetermined intervals in the left-right direction and the front and back directions in FIG. Arranged in a grid.

As shown in FIG. 1, the circuit board 50 is formed by laminating a back sheet 53, an insulating adhesive layer 52, and a metal electrode 51 in this order. The back sheet 53 is a member having a barrier property and a function of a base material as a support. The barrier property is a function for constituting one outer surface in the stacking direction of the circuit board 50 and suppressing intrusion of moisture, oxygen or the like into the solar cell module 60, and a barrier function as a shield material have.
It is also possible to separate the barrier function into layers, and in this case, as a material, an appropriate resin material having excellent barrier properties against moisture and oxygen, a fluorine resin material, an aluminum foil, or an aluminum foil A composite laminated film with an appropriate resin can be used.

  The base material used for the back sheet 53 is a member that supports the metal electrode 51 via the insulating adhesive layer 52, and is composed of a flexible sheet-like member. The substrate is preferably made of a material having excellent electrical insulation. As a base material, what formed the resin material in the sheet form or the film form is employable, for example. As the resin material, for example, a resin material such as acrylic, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, polyimide, urethane, epoxy, melamine, or styrene, or a resin material obtained by copolymerization thereof can be used.

  As a material for the substrate, a material mixed with an organic filler, an inorganic filler, or the like can be used as necessary for controlling heat insulation, elasticity, and optical characteristics. Moreover, it is also possible to employ a laminated film in which a plurality of the above resin materials are laminated, or a composite laminated film in which a layer of the above resin material and a metal foil such as an aluminum foil are laminated as the base material. .

  The insulating adhesive layer 52 is a layered portion for fixing the metal electrode 51 to the surface of the back sheet 53. For example, urethane, acrylic, epoxy, polyimide, olefin, which is a curable resin, or a copolymer thereof is copolymerized. It is formed by curing a curable adhesive. The type of the curable adhesive is not particularly limited, and for example, a thermosetting adhesive, a UV curable adhesive, or the like can be suitably employed. Moreover, although it is preferable to use a step-curing adhesive as the insulating adhesive layer 52, an adhesive that is not a step-curing type may be used.

  The metal electrode 51 forms a wiring pattern that is electrically connected to the solar battery cell 20. As the material of the metal electrode 51, an appropriate metal material having good electrical conductivity can be adopted. For example, examples of the metal electrode 51 include copper, aluminum, and iron.

As the planar view shape of the metal electrode 51, that is, the wiring pattern, for example, both the positive electrode 51a and the negative electrode 51b are comb-shaped, and these comb-shaped portions penetrate into the gaps between the linear portions. In addition, patterns that are closely spaced apart from each other can be cited. The cut portions of the metal electrode 51 are short-circuit prevention layers 54a and 54b made of oxide formed by heating and oxidizing the surface layer of the metal electrode 51. The forming method will be described later.
In addition, it is only necessary that the connection between the positive electrode 20a and the negative electrode 20b of the solar battery cell 20 in the solar battery module 60 can be electrically separated, and the solar battery module 60 is not limited to a plan view shape such as a comb shape.

  The sealing material 30 only needs to be able to seal and insulate the solar cell 20 from the metal electrode 51 supported on the insulating adhesive layer 52 and the insulating adhesive layer 52 of the circuit board 50, and from an appropriate material. You can choose. Suitable materials for the sealing material 30 include a film material made of a thermoplastic resin, for example, an ethylene / vinyl acetate copolymer (EVA), an ethylene / methacrylic acid copolymer (EMAA), or the like.

As shown in FIG. 1, the encapsulant 30 of the present embodiment sandwiches the solar battery cell 20 between an encapsulant sheet 32 and a transparent encapsulant sheet 31 composed of the above-described thermoplastic resin film material. It is formed by integrating both by lamination.
For this reason, in the solar cell module 60, the boundary between the sealing material sheet 32 and the transparent sealing material sheet 31 is not particularly problematic when the same material is used, but when different materials are used, the color, the transmittance, or the refractive index. For example, an interface 33 as shown by a two-dot chain line in FIG. 1 may be recognized.

  The sealing material sheet 32 may not have light transmittance in the sealing material region closer to the circuit board 50 than the light receiving surface 20 c of the solar battery cell 20. As the material of the sealing material sheet 32 for this region, various films having light absorption, light scattering, and light reflectivity can be employed. For example, a colored (including white) film containing a color material having a suitable color, such as a black film or a white film, can be suitably employed. By adopting such a colored film as the sealing material sheet 32, the upper surface of the circuit board 50 cannot be visually recognized through the gap between the solar battery cells 20 from the translucent substrate 40 side. Can be improved.

On the other hand, the transparent sealing material sheet 31 is a film member for sealing the solar battery cell 20 from the light receiving surface 20c side. The transparent sealing material sheet 31 is required to have light transmittance so as not to interfere with the light reception of the solar battery cell 20, and is most preferably colorless and transparent.
In the present embodiment, the thickness of the transparent sealing material sheet 31 has a thickness substantially corresponding to the layer thickness from the back surface 20 d of the solar battery cell 20 to the translucent substrate 40 in the solar battery module 50.

  The conductive connecting material 10 may be any material that can electrically connect the connection electrodes 20a and 20b of the solar battery cell 20 and the metal electrodes 51a and 51b when forming the solar cell module 60 described later. Examples thereof include conductive adhesives such as silver paste, copper paste, and carbon paste, tin, and nickel-based low melting point solder.

  A method for processing the metal electrode 51 will be described with reference to FIG. In FIG. 2 (a), a back sheet 53, an insulating adhesive layer 52, and a metal foil sheet 51 are sequentially superposed on each other, and heated and pressed to form a sheet according to the bonding conditions of the insulating adhesive layer 52. showed that.

  A method for forming the circuit pattern of the metal electrode 51 will be described with reference to FIG. Although the detailed drawing is omitted, the punching blade 70 is formed on the surface of a flat punching die. The cutting blade 70 has an isosceles triangular longitudinal section that narrows in the protruding direction, and forms a cutting edge at the tip in the protruding direction. The height h to the cutting edge of the punching blade 70 is larger than the thickness of the metal foil layer 51 and is set to a height that does not penetrate the insulating adhesive layer 52.

The punching blade 70 can use a corrosion mold, a cutting mold or the like, but is not limited thereto. Pre-hardened steel, quenching and tempering steel, precipitation hardened steel, alloys of tungsten carbide and cobalt, other superhard alloys, etc. can be used as the material for forming the punching die 30. There is no limit.

  In order to form a metal electrode pattern (circuit pattern) from the metal foil state using the punching blade 70, the metal foil 51 is pressed after positioning at the place where the punching blade 70 is put. Thereby, as shown in FIG. 2B, the cutting edge of the punching blade 70 cuts the metal foil 51, and the tip of the cutting edge C reaches the insulating adhesive layer 52. The metal foil 51 is plastically deformed along the side surface shape of the punching blade 70 to form a V-shaped groove shape to which the outer shape of the punching blade 70 is transferred, and the metal electrode pattern 51 is formed.

  By at least partially burying in the insulating adhesive layer 52, even if the metal foil is deformed due to subsequent heating or aging, the cut end faces are prevented from contacting each other, and the cut end faces are brought into contact with each other. Can be prevented. In addition, when a pattern is formed, in accordance with the resin formation characteristics of the insulating adhesive layer 52, for example, when a thermosetting resin is used, it is more robust by heating to the curing temperature after inserting the blade. A simple circuit pattern can be formed.

  In conventional punching circuit pattern formation, metal foil was punched into a circuit pattern shape using two parallel punching blades, and unnecessary foil between the circuit patterns was removed. Cutting burrs sometimes appeared on the circuit surface side. However, in the pattern formation of the present proposal, burrs at the time of punching are embedded on the insulating adhesive layer 52 side, and generation on the circuit surface is reduced.

  A method of forming the short-circuit prevention layer 54 provided on the end face of the metal electrode 51 will be described with reference to FIG. FIG. 3A shows a case where a patterned and separated metal electrode 51 is formed on an insulating adhesive layer 52, and an AC power source is installed between the separated metal electrodes 51a and 51b, and an appropriate current is applied. It shows how to play.

FIG. 3B shows a state in which the cut surface is selectively heated by the resistance of the reactance in which the cut surface is regarded as a capacitor, and the cut end surface of the metal is heated and oxidized by applying an alternating current. If aluminum, the oxide film (Al ₂ O ₃ ) becomes thick, if copper, black cupric oxide (CuO) is formed; if iron, black triiron tetroxide (Fe ₃ O ₄ ) is formed. Form. The cut surface is selectively heated, and the insulating short-circuit prevention layer 54 is formed only by the metal oxide at the cut portion. By being heated and oxidized in air, an oxide film with improved insulation can be formed.

A method for manufacturing the solar cell module 60 of the present embodiment will be described.
In order to form the circuit board 50, the back sheet 53, the insulating adhesive layer 52, and the metal foil 51 are laminated in this order. After these layers are joined together, the circuit board 50 is formed by punching and applying an alternating current. As a bonding method, various known methods such as dry lamination and extrusion lamination may be appropriately selected.

  Next, according to the position of the connection electrodes 20a and 20b of the solar battery cell 20, the conductive connection material 10 is printed on the circuit board 50 by using, for example, a screen printing method. It is only necessary to be able to form a pattern, and the printing method is not particularly concerned. Similarly, through holes 32 a are formed in the sealing material 32 in accordance with the positions of the connection electrodes 20 a and 20 b of the solar battery cell 20. As a method for opening the through hole, an existing method such as punching using a die punch, laser processing, or a drill can be employed. The diameter of the through hole is preferably equal to or larger by 1 to 2 mm than the connection electrodes 20a and 20b.

As shown in FIG. 4, the circuit board 50 on which the conductive connecting material 10 is printed, the sealing material 32, the solar battery cell 20, the transparent sealing material sheet 31, and the translucent substrate 40 are arranged in this order.
In this way, the laminated body 65 shown in FIG. 5 in which the circuit board 50, the sealing material 32, the solar battery cell 20, the transparent sealing material sheet 31, and the translucent substrate 40 are laminated is formed.

  Next, using a laminator, vacuum pressurization laminating is performed in which the laminated body 65 is heated in the laminating direction under vacuum. The processing conditions of the heating temperature and the applied pressure are such that the encapsulant sheet 32 and the transparent encapsulant sheet 31 are softened and deformed, and can be adhered to and adhered to the surfaces of adjacent members, and The conductive bonding material 10 and the connection electrodes 20a and 20b, and the conductive bonding material 10 and the metal electrode 51 are electrically heated and applied with pressure.

  By such a laminating process, the conductive bonding material 10 sandwiched between the substrate electrode portion and the connection electrodes 20a and 20b is pressurized and heated in the thickness direction. As a result, the conductive bonding material 10 is cured, and the metal electrode 51 and the connection electrodes 20 a and 20 b are bonded by the conductive bonding material 10.

  Moreover, the sealing material sheet 32 and the transparent sealing material sheet 31 are softened and deformed and integrated by heating in the lamination process. Further, the softened sealing material sheet 32 and the transparent sealing material sheet 31 flow and are in close contact with the surfaces of adjacent members. Thereby, the outer peripheral part of the photovoltaic cell 20 is sealed, and the layer of the sealing material 30 is formed between the circuit board 50 and the translucent substrate 40. When the heating and pressurization are completed, the layers of the laminate 65 are solidified in a bonded state, and the solar cell module 60 as shown in FIG. 1 is completed.

  According to the solar cell module 60 of the present embodiment, it is possible to provide a circuit that eliminates the need to remove unnecessary portions when forming a circuit pattern and can reduce problems caused by edge burrs in the conductive circuit, and is inexpensive and reliable. A highly efficient solar cell module can be provided.

  Next, an example and a comparative example are shown about a solar cell bonding material assembly and a solar cell module of the present invention.

Example 1
As the sealing material sheet 32 of the present example, a white EMAA film having a thickness of 200 μm was used, and the diameter of the through hole 32a was 3 mm (see FIG. 4). As a material of the metal electrode 51, an aluminum foil made of high-purity aluminum (purity 99% or more) having a thickness of 50 μm was used. The insulating adhesive layer 52 was previously formed on the back sheet 53 with a film thickness of 50 μm using Elephant CS (trade name; manufactured by Yodogawa Paper Co., Ltd.), a thermosetting epoxy resin. The circuit board 50 was formed by laminating the back sheet 53, the insulating adhesive layer 52, and the metal foil 51 in this order and press-bonding them with a dry laminator.

  Further, the metal foil 51 is punched using a punching blade 70 having a blade height h = 80 μm, the cut end surface of the metal electrode 20 is embedded in an insulating adhesive, and the metal electrode 51 is processed into a comb pattern, and then the metal electrode 51a. An alternating electric field of 50 Hz and 10 V was applied between the first and second 51b. When the aluminum oxide film thickness on the end face of the metal electrode 51 before and after the application was measured with a transmission electron microscope (TEM), it increased from 5 nm to 25 nm. A short-circuit prevention layer 54 was formed by the growth of the oxide film. At the same time, the insulating adhesive layer 52 at the end face portion of the metal electrode 51 was heated and flowed to cover the end face of the metal electrode 51 and the protective layer 55 was formed.

The solar cell module 60 of this example includes a circuit board 50, a conductive bonding material 10, a sealing material sheet 32, a solar cell 20, a transparent sealing material sheet 31, which are arranged in accordance with the arrangement of the connection electrodes 20a of the solar cells 20. A translucent substrate 40 made of a glass plate having a thickness of 3 mm was laminated in this order, and the module lamination was performed by a module laminator. Here, the conductive bonding material 10 was formed by screen printing using a conductive paste Pertron S-3028 (trade name; manufactured by Pernox Co., Ltd.). Moreover, the transparent sealing material sheet 31 used the transparent EVA film with a thickness of 300 micrometers. The module lamination was performed under vacuum at 150 ° C. for 3 minutes, followed by pressurization in the laminating direction at 150 ° C. and 1 × 10 ⁵ N / m ² for 12 minutes. In the solar cell module 60 manufactured in this way, the solar cells 20 were well electrically connected to the metal electrode 51, and no conduction failure occurred.

(Comparative example)
In the solar cell module of the example, a solar cell module of a comparative example was produced in the same manner as in the example except that the metal electrode 51 end face heat treatment was not performed and the protective layer 55 was not formed.
In this comparative example, there was an electrical connection failure due to a short circuit between the electrodes.

  The embodiments and examples of the present invention have been described above. However, the technical scope of the present invention is not limited to the above-described embodiments, and combinations of components may be changed without departing from the spirit of the present invention. Various changes can be added to or deleted from each component.

DESCRIPTION OF SYMBOLS 10 Conductive bonding material 20 Solar cell 20a Positive connection electrode 20b Negative connection electrode 20c Solar cell light-receiving surface 20d Solar cell back surface 30 Sealing material 31 Transparent sealing material sheet 32 Sealing material sheet 32a Through-hole 33 Interface 40 Light transmission Substrate 50 Circuit board 51 Metal electrode (or metal foil)
52 Insulating Adhesive Layer 53 Back Sheet 54 Short-Circuit Prevention Layer 55 Protective Layer 60 Solar Cell Module 65 Laminate 70 Punching Blade

Claims (4)

In a circuit board in which a base material, an adhesive layer, and a metal electrode are sequentially laminated,
A circuit board comprising a short-circuit prevention layer made of an oxide of a metal composing the metal electrode on an end surface portion of the metal electrode. A step of sequentially laminating a base material, an adhesive layer, and a metal foil;
Cutting the metal foil by punching to form a metal electrode pattern;
The method of manufacturing a circuit board according to claim 1, further comprising: oxidizing the end face of the metal electrode pattern to form a short-circuit prevention layer.   The method for manufacturing a circuit board according to claim 2, wherein the metal electrode is aluminum, copper, iron, or an alloy thereof.   A solar cell module comprising the circuit board according to claim 1.

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