JP5692347B2 - Conductive adhesive - Google Patents

Description

  The present invention relates to a solar battery module in which a surface electrode of a solar battery cell is connected to a tab wire, and a manufacturing method thereof.

The solar cell module is formed by connecting a plurality of solar cells in series, and the surface electrode of at least one of the solar cells is connected to a tab wire made of a ribbon-like copper foil coated with solder. . Specifically, in the crystalline solar cell module, the bus bar electrode formed by screen printing of silver paste on the light receiving surface of the solar cell, a tab lead functioning as inner leads are connected by solder da treatment cage, in the thin-film solar cell module, the solar cell surface electrode at both ends, the tab line are connected by solder da treated as outer lead for power extraction (patent document 1).

However, by heating at the time of solder da treatment, or warp the solar cell, the internal stress or occur in connection of the tab lead and the surface electrode, resulting in the surface electrode and the tab line when the solar cell There was a problem that the connection reliability between the two was lowered.

  Therefore, in recent years, a conductive adhesive film that can be connected by thermocompression treatment at a relatively low temperature has been used to connect the surface electrode of the solar battery cell and the tab wire (patent document). 2). As such a conductive adhesive film, a film obtained by dispersing spherical conductive particles having an average particle size of the order of several μm in a thermosetting binder resin composition is used. In addition, as the spherical conductive particles, spherical metal particles having relatively high hardness and spherical resin particles coated with relatively low hardness are used.

JP 2004-356349 A JP 2008-135654 A

  By the way, since most of the surface electrodes of the solar battery cells are formed by applying and heating a silver paste, irregularities of the order of several μm are usually formed on the surface of the surface electrode, and spherical conductive particles There are also variations in diameter.

  For this reason, when spherical metal particles having a relatively high hardness are used as the conductive particles to be blended in the conductive adhesive film, the spherical metal particles having a relatively large particle size are interposed between the surface electrode of the solar battery cell and the tab wire. When sandwiched, spherical metal particles having a smaller particle diameter cannot contact the surface electrode and the tab wire at the same time and do not contribute to the connection. As a result, the connection reliability between the surface electrode and the tab wire is reduced. There was a problem that decreased.

  On the other hand, when using relatively low-hardness metal-plated spherical resin particles, the metal-plated spherical resin particles sandwiched between the surface electrode of the solar cell and the tab wire are subjected to thermocompression treatment at the time of connection. Because it is flattened out, there is nothing or no if any that does not contribute to the connection. However, from the viewpoint of reducing the material cost of the surface electrode, when an Al paste or an Al deposited film is applied instead of the silver paste, the metal-plated spherical resin particles are flattened during the thermocompression treatment at the time of connection. Although deformed, the surface passivated film of the Al deposited film was not destroyed, and as a result, there was a problem that the connection reliability between the surface electrode of the solar battery cell and the tab wire was lowered.

  An object of the present invention is to solve the above-described problems of the conventional technique, in which a plurality of solar cells are connected in series, and a surface electrode of at least one solar cell is connected to a tab wire. In the solar cell module, the connection reliability between the surface electrode and the tab wire can be ensured regardless of the presence or absence of the surface unevenness or the material of the surface electrode.

  As the conductive particles used in the conductive adhesive film, the present inventors have a flake shape in which at least 50% by mass has a specific size and aspect ratio, and has higher hardness than the surface electrode and the tab wire. The inventors have found that the above object can be achieved by using metal particles, and have completed the present invention.

That is, the present invention is a solar cell module in which a plurality of solar cells are connected in series, and in the solar cell module in which the surface electrode of at least one solar cell is connected to the tab wire,
The surface electrode of the solar battery cell and the tab wire are connected by thermocompression bonding through a conductive adhesive layer in which conductive particles are dispersed in a binder resin composition, and 50% by mass or more of the conductive particles are It has a major axis of 1 to 50 μm, a thickness of 5 μm or less, and a major axis / thickness aspect ratio (= major axis / thickness) of 3 to 150, and higher hardness than the first electrode, the second electrode, and the tab wire. Provided is a solar cell module characterized by having flaky metal particles.

Further, the present invention provides a method for manufacturing a solar cell module in which a plurality of solar cells are connected in series, and a surface electrode of at least one solar cell is connected to a tab wire.
A step of laminating a conductive adhesive layer formed by dispersing conductive particles in a binder resin composition on the surface electrode of the solar battery cell;
A step of arranging a tab wire on the conductive adhesive layer; and a thermocompression treatment from the tab wire side on the conductive adhesive layer to electrically connect the surface electrode of the solar cell and the tab wire. Having a process,
50% by mass or more of the conductive particles have a major axis of 1 to 50 μm, a thickness of 5 μm or less, and an aspect ratio (= major axis / thickness) of 3 to 150 and higher hardness than the surface electrode and the tab wire. Provided is a method for producing a solar cell module, characterized in that it is a flaky metal particle.

  In the solar cell module in which the conductive adhesive film is used, a plurality of solar cells are connected in series, and the surface electrode of at least one solar cell is connected to the tab wire, as conductive particles to be blended in the conductive adhesive film, At least 50% by mass or more uses flaky metal particles having a major axis of 1 to 50 μm, a thickness of 5 μm or less, and an aspect ratio (= major axis / thickness) of 3 to 150. Since such flaky metal particles have a flat shape, they can overlap each other when sandwiched between the surface electrode of the solar battery cell and the tab wire. The number can be eliminated or reduced as much as possible. Therefore, good connection reliability can be ensured regardless of the presence or absence of surface irregularities of the electrodes normally used for solar cells.

  Moreover, this flaky metal particle has hardness higher than the surface electrode and tab wire | line of a photovoltaic cell. Therefore, even when Al paste or Al deposited film is used to form these electrodes, the surface passivation film of aluminum can be destroyed during the thermocompression treatment, and good connection reliability can be obtained. Can be secured. In addition, good adhesiveness can be secured even for a curable Ag paste electrode in which Ag powder is kneaded with epoxy resin.

It is a general | schematic fragmentary sectional view of the solar cell module of this invention. It is a schematic whole sectional view of the solar cell module of the present invention. It is a schematic top view of the solar cell module of the present invention. It is a schematic perspective view of a flaky metal particle.

  Hereinafter, an example of the solar cell module of the present invention will be described with reference to the drawings.

  In the solar cell module of the present invention, a plurality of solar cells are connected in series, and the surface electrode of at least one solar cell is connected to a tab wire.

  The solar cell to which the present invention is applied has a photoelectric conversion element as a photoelectric conversion part. As the photoelectric conversion element, a single crystal silicon photoelectric conversion element, a polycrystalline silicon photoelectric conversion element, a microcrystalline silicon photoelectric conversion element, an arbitrary silicon photoelectric conversion element including an amorphous silicon type solar cell element, GaAs Other semiconductor compound-based photoelectric conversion elements such as a type and a calcobylite type, and dye-based photoelectric conversion elements such as a dye-sensitized solar cell can be used. An ITO thin film electrode may be formed on these surfaces as necessary.

  Solar cells composed of these photoelectric conversion elements can be broadly classified into thin-film solar cells and other crystalline solar cells.

  Hereinafter, an example of the solar cell module of the present invention using a crystalline solar cell will be described.

  FIG. 1 is a schematic partial sectional view of a solar cell module 100 of the present invention. In this solar cell module 100, a plurality of solar cells 50 are connected in series with tab wires 30 that function as interconnectors. Here, the solar cell 50 includes a photoelectric conversion element 10, a first electrode 21 that is a bus bar electrode that is a surface electrode provided on the light receiving surface thereof, and a second electrode 23 that is a bus bar electrode provided on a non-light receiving surface. The finger electrodes 22 and 24 that are collector electrodes provided on the photoelectric conversion element 10 so as to be substantially orthogonal to the first electrode and the second electrode.

  As shown in FIG. 2, the solar cell module 100 of FIG. 1 is usually made of a metal frame 200 such as aluminum, a translucent surface protective material 201 such as glass or translucent plastic, and an aluminum foil made of a resin film. Is sealed with a light-transmitting sealing material 203 such as ethylene vinyl alcohol resin (EVA).

  In the solar cell module of the present invention having such a structure, as shown in FIG. 1, the tab wire 30, the first electrode 21, and the second electrode 23 are made of conductive adhesive in which conductive particles are dispersed in a binder resin. The layers 40 are connected by thermocompression treatment.

  In the present invention, flat flaky metal particles are used as the conductive particles. The flat flaky metal particles can overlap each other when sandwiched between the first electrode or the second electrode of the light receiving surface of the solar battery cell and the tab wire, and therefore, the conductive particles not involved in the connection The number can be eliminated or reduced as much as possible, and good connection reliability can be ensured regardless of the presence or absence of surface irregularities of the normal electrodes used in solar cells.

  As the flaky metal particles, flaky metal particles of metals and alloys such as nickel, silver and solder can be used. Among them, flaky nickel particles can be preferably used from the viewpoint of low cost and good conductivity. .

  The flaky metal particles used in the present invention have a major axis of 1 to 50 μm, preferably 1 to 40 μm, and a thickness of 5 μm or less, preferably 3 μm or less. Regarding the major axis, if it is less than 1 μm, the conduction resistance after connection tends to be high, and if it exceeds 50 μm, there is a tendency that a problem arises in film applicability when the film is formed. Moreover, when the thickness exceeds 5 μm, the insulation resistance tends to be low. The major axis and thickness of the flaky metal particles are numerical values measured by appearance observation with a microscope or the like.

  Furthermore, the flaky metal particles used in the present invention have an aspect ratio of 3 to 150, preferably 3 to 100, as shown in FIG. When the aspect ratio exceeds 150, the conduction resistance after connection tends to increase.

  In addition, the flaky metal particles exhibit higher hardness than the first electrode on the light receiving surface of the solar battery cell, the second electrode on the non-light receiving surface, and the tab line. Therefore, even when Al paste or Al vapor deposition film is used to form these electrodes, the surface passivation film of aluminum can be destroyed during the thermocompression treatment, and the tab wire It can bite in and can ensure good connection reliability.

  In the present invention, the conductive particles in the conductive adhesive layer 40 contain flaky metal particles as described above at 50% by mass or more, preferably 60% by mass or more.

  If the content of the conductive particles in the conductive adhesive layer 40 used in the present invention is too small, the connection reliability is not sufficient, and if it is too large, the connection strength becomes insufficient, preferably 3 to 30% by mass, More preferably, it is 3-20 mass%.

  As the binder resin composition constituting the conductive adhesive layer 40, it can be appropriately selected from thermosetting binder resin compositions used in conventional conductive adhesives. For example, a binder resin composition in which a curing agent such as an imidazole curing agent or an amine curing agent is blended with a thermosetting epoxy resin, a thermosetting urea resin, a thermosetting melamine resin, a thermosetting phenol resin, or the like. be able to. Especially, when the point with the favorable adhesive strength after hardening is considered, the binder resin composition using a thermosetting epoxy resin can be used preferably.

  Such a thermosetting epoxy resin may be liquid or solid, and preferably has an epoxy equivalent of usually about 100 to 4000 and having two or more epoxy groups in the molecule. For example, a bisphenol A type epoxy compound, a phenol novolac type epoxy compound, a cresol novolac type epoxy compound, an ester type epoxy compound, an alicyclic epoxy compound, or the like can be preferably used. These compounds include monomers and oligomers.

  The binder resin composition used in the present invention can contain a filler such as silica and mica, a pigment, an antistatic agent, and the like, if necessary. Coloring agents, preservatives, polyisocyanate crosslinking agents, silane coupling agents, and the like can also be blended.

  Moreover, well-known spherical or irregular-shaped electroconductive particle can also be mix | blended. When spherical conductive particles are blended in addition to the flaky metal particles, the conduction resistance value can be further stabilized, and the amount of the flaky metal particles used can be reduced to reduce the manufacturing cost of the conductive adhesive. It is done. Such spherical conductive particles preferably have an average particle diameter of 1 to 10 μm and smaller than the major axis of the flaky metal particles. Moreover, it is preferable that the compounding quantity of spherical or irregular-shaped electroconductive particle is 0.01-1 times the compounding quantity (mass part) of flaky metal particle.

The conductive adhesive layer 40 in the present invention is used as a paste-like conductive adhesive or a film-like conductive adhesive film, but if its melt viscosity is too low, it will flow from the temporary compression bonding to the main curing process, resulting in poor connection. And protrusion to the light-receiving surface. Even if it is too high, defects are likely to occur at the time of application or film sticking. In the case of a paste, the viscosity at 25 ° C. measured with a cone plate viscometer is preferably 50 to 200 Pa · s, more preferably 50 to 150 Pa · s, and in the case of a film, the lowest melt viscosity measured with a cone plate viscometer is preferably 1 × 10 ² to 1 × 10 ⁵ Pa · s, more preferably 1 × 10 ^{2 to} 5 ×. 10 ⁴ Pa · s.

  In the present invention, the conductive adhesive layer 40 is a known coating applied to the first electrode and the second electrode of the solar cell by applying a conductive adhesive in which conductive particles are uniformly dispersed in a thermosetting binder resin composition according to a conventional method. It can be formed by the method. Moreover, it can form by transferring the conductive adhesive layer of the conductive adhesive film obtained by forming a conductive adhesive on a peeling base film and drying it to the first electrode and the second electrode.

  In addition, since the layer thickness of the conductive adhesive layer 40 is insufficient when it is too thin, and when it is too thick, the conductive adhesive layer 40 may protrude from the light receiving surface, so it is preferably 5 to 50 μm, more preferably 10 to 40 μm.

  As the 1st electrode 21 of the light-receiving surface of the photovoltaic cell 50, and the 2nd electrode 23 of a non-light-receiving surface, it can be set as the structure similar to the bus-bar electrode of a conventionally well-known solar cell. For example, it is formed by applying silver paste or Al paste and heating.

  For example, the first electrode 21 formed on the light receiving surface of the solar battery cell 50 is usually formed in a line shape with a width of about 1 mm in order to minimize the area that blocks incident light. The number of the first electrodes 21 is appropriately set in consideration of the size and resistance of the solar battery cell. Further, by the same method, the line-shaped finger electrodes 22 having a width of about 100 μm are formed at intervals of about 2 mm over almost the entire light receiving surface of the photoelectric conversion element 10 so as to intersect the first electrode. .

  Moreover, the 2nd electrode 23 and finger electrode 24 which are formed in the non-light-receiving surface of the photovoltaic cell 50 can also be set as the structure similar to the 1st electrode 21 and finger electrode 22 which are formed in a light-receiving surface. Note that the second electrode on the non-light-receiving surface does not need to consider incident light, and may be formed so as to cover substantially the entire back surface of the photoelectric conversion element 10. In that case, the finger electrode 24 becomes unnecessary.

  As the tab wire 30, a tab wire used in a conventional solar cell module can be used. For example, a ribbon-like copper foil having a thickness of 50 to 300 μm can be preferably used. Such a ribbon-like copper foil can be subjected to gold plating, silver plating, tin plating, solder plating, or the like, if necessary.

  As described above, the first electrode, the second electrode, and the tab wire 30 are softer than the flaky metal particles. For example, when the flaky metal particles are nickel particles (Mohs hardness = 3.5), at least the surface of the first electrode, the second electrode, and the tab wire is gold (Mohs hardness = 2.5), silver ( It is preferably composed of Mohs hardness = 2.7), copper (Mohs hardness = 3.0), aluminum (Mohs hardness = 2.9), tin (Mohs hardness = 3.0) and the like.

  Next, the solar cell module of the present invention shown in FIG. 1 can be manufactured as follows.

  On the release film, a conductive adhesive in which conductive particles containing 50% by mass or more of predetermined flaky metal particles are dispersed in an epoxy resin composition is applied to a dry thickness of 10 to 40 μm and dried. A conductive adhesive film is formed.

  The conductive adhesive layer of the conductive adhesive film is temporarily bonded to the first electrode and the second electrode of the solar battery cell, and the release film is peeled off to laminate the conductive adhesive layer on the first electrode and the second electrode. To do.

  In addition, you may form a conductive contact bonding layer on a 1st electrode and a 2nd electrode by screen printing etc. with a paste form, without forming a conductive adhesive into a film.

  Next, a tab wire is disposed between the first electrode on the light receiving surface of the solar battery cell and the second electrode on the non-light receiving surface of the adjacent solar ionization cell, and pressurizing at about 0.1 to 5 MPa. Temporarily affixing by heating at a temperature of 0.2 to 10 seconds and then pressing at about 0.1 to 5 MPa while heating at 140 to 200 ° C. for 10 to 20 seconds, thereby performing a plurality of press bonding Connect the solar cells in series. In addition, when a paste-like conductive adhesive is used, the temporary sticking step can be omitted.

  Next, a light-transmitting surface protective material such as glass, a sealing sheet such as EVA, a plurality of solar cells connected in series, a sealing sheet such as EVA, and a back surface protective material were stacked in this order and evacuated. Then, it laminates at 120 to 150 ° C. for 5 to 20 minutes. Then, it hardens | cures completely by heating at 120-150 degreeC for 30-60 minutes. Then, a terminal box and a metal frame are attached, and a solar cell module can be obtained.

  Next, an example of the solar battery module of the present invention using thin film solar cells will be described with reference to FIG. In such a thin-film solar cell module, a long thin-film photoelectric conversion element is directly connected in the horizontal direction, and a tab wire for power extraction is connected to the electrode of the photoelectric conversion element. In this way, the resin is sealed.

  In the thin film solar cell module 100 of FIG. 3, thin film solar cells 32 made of thin film photoelectric conversion elements are arranged in series on a substrate 38 in a planar direction, and the solar cell 32 c at one end is arranged. A tab wire 34 for taking out electric power is connected to a surface electrode (not shown) and a surface electrode (not shown) of the solar cell 32d at the other end via an adhesive. In principle, the thin-film solar cells 32 and the configuration other than the use of tab wires for connection between solar cells are the same as those of the crystalline solar cell module described in FIG.

  Such a thin-film solar cell module is used to extract power from the surface electrode (not shown) of the solar cell 32c at one end and the surface electrode (not shown) of the solar cell 32d at the other end. The tab wire 34 is temporarily pasted by pressing at room temperature or low temperature (about 30 to 120 ° C.) through the adhesive described in the crystalline solar cell module of FIG. 1, and relatively high temperature (about 140 to 200). (° C.).

  In addition, prepare a plurality of solar cell modules obtained in this way, connect them in series to create a solar cell string, further prepare a plurality of such solar cell strings, connect them in parallel By doing so, a solar cell array can be obtained.

  In addition, the conductive adhesive used in the present invention, that is, the conductive adhesive for connecting the surface electrode of at least one solar battery cell of the solar battery module in which a plurality of solar battery cells are connected in series to the tab wire is also used. The conductive particles are dispersed in the binder resin composition, which is a part of the present invention. 50% by mass or more of the conductive particles have a major axis of 1 to 50 μm and a thickness of 5 μm or less. And flaky metal particles having an aspect ratio (major axis / thickness) of 3 to 150 and higher hardness than the surface electrode and the tab wire. The specific configuration is as described above.

  Hereinafter, the solar cell module of the present invention will be specifically described with reference to test examples and examples, but the present invention is not limited to those shown in the following examples, and the gist thereof is not changed. In the range, it can implement by changing suitably.

Example 1
(1) Production of conductive adhesive film 10 parts by mass of conductive particles containing 50 mass% or more of scaly Ni particles (Mohs hardness 3.8) having a major axis of 1 to 20 μm, a thickness of 3 μm or less, and an aspect ratio of 3 to 50; A-type epoxy resin (EP828, Japan Epoxy Resin Co., Ltd.) 50 parts by mass, phenoxy resin (YP-50, Toto Kasei Co., Ltd.) 20 parts by mass, and imidazole-based latent curing agent (HX3941HP, Asahi Kasei Co., Ltd.) A conductive adhesive was prepared by mixing 20 parts by mass and further 100 parts by mass of toluene.

  The resulting conductive adhesive was applied to a 50 μm thick release-treated polyethylene terephthalate film to a thickness of 25 μm, and heated and dried in an oven at 80 ° C. for 5 minutes to form a conductive adhesive film. did.

(2) Production of solar cell module model (2a) As an alternative to the photoelectric conversion element, the following three types of glass plates having a length of 80 mm, a width of 15 mm, and a thickness of 0.7 mm were prepared.
(2ai) An ITO solid glass plate provided with an indium-titanium composite oxide layer having a thickness of 150 to 200 nm was prepared as an electrode. The Mohs hardness of the ITO surface was 4 or more. The roughness of the electrode surface was 0.2 μm or less.
(2aii) An Al solid glass plate provided with an aluminum vapor deposition film having a thickness of 500 nm was prepared as an electrode. The Mohs hardness of the Al surface was 2.9. The roughness of the electrode surface was 0.2 μm or less. A strong passive film was formed on the aluminum surface.
(2aiii) An Ag solid glass plate provided with a 5 μm thick Ag paste fired film was prepared as an electrode. The Mohs hardness on the Ag surface was 2.7. The roughness of the electrode surface was 4 μm or less. A weak oxide film was formed on the Ag surface.

(2b) On the other hand, the following two types of tab lines were prepared as tab lines.
(2bi) 150μm thick copper foil with SnAgCu solder dip plating (plating thickness 40μm)
A solder-coated copper ribbon subjected to the above was prepared. The Mohs hardness of the surface was 3 or less.
(2bii) A solid copper ribbon having a thickness of 150 μm was used as a tab wire. The Mohs hardness of the surface was 3.

(2c) A solar cell module by thermally bonding the conductive adhesive layer of the conductive adhesive film to 12 locations on the electrode layer as an alternative to the photoelectric conversion element (connection area 2 mm square, 180 ° C., 3 MPa, 15 seconds) A model was created. With respect to the obtained solar cell module model, the maximum resistance value and the minimum resistance value were measured by the four-terminal method, and the average resistance value was calculated, and the average resistance value was evaluated according to the criteria shown in Table 1 below. The obtained results are shown in Table 2.

Example 2
Implementation was performed except that conductive particles containing 50 mass% or more of flaky Ni particles (Mohs hardness 3.8) having a major axis of 20 to 40 μm, a thickness of 3 μm or less, and an aspect ratio of 50 to 100 were used as the flaky Ni particles. By repeating Example 1, a conductive adhesive film and a solar cell module model were produced. With respect to the obtained solar cell module model, the maximum resistance value and the minimum resistance value were measured by a four-terminal method, and the average resistance value was calculated and evaluated based on the same criteria. The obtained results are shown in Table 2.

Example 3
Implementation was performed except that conductive particles containing 50 mass% or more of flaky Ni particles having a major axis of 40 to 50 μm, a thickness of 3 μm or less, and an aspect ratio of 100 to 150 (Mohs hardness 3.8) were used as the flaky Ni particles. By repeating Example 1, a conductive adhesive film and a solar cell module model were produced. With respect to the obtained solar cell module model, the maximum resistance value and the minimum resistance value were measured by a four-terminal method, and the average resistance value was calculated and evaluated based on the same criteria. The obtained results are shown in Table 2.

Comparative Example 1
A conductive adhesive film and a solar cell module model were produced by repeating Example 1 except that spherical Ni particles having an average particle diameter of 10 μm (Mohs hardness 3.8) were used in place of the scale-like Ni particles. With respect to the obtained solar cell module model, the maximum resistance value and the minimum resistance value were measured by a four-terminal method, and the average resistance value was calculated and evaluated based on the same criteria. The obtained results are shown in Table 2.

Comparative Example 2
A conductive adhesive film and a solar cell module model were produced by repeating Example 1 except that spherical solder particles having an average particle size of 10 μm (Mohs' hardness of 2 or less) were used instead of the scale-like Ni particles. With respect to the obtained solar cell module model, the maximum resistance value and the minimum resistance value were measured by a four-terminal method, and the average resistance value was calculated and evaluated based on the same criteria. The obtained results are shown in Table 2.

  As can be seen from Table 2, in the solar cell module models of Examples 1 to 3 using a conductive adhesive film containing flat flaky metal particles having a long diameter, thickness and aspect ratio in a specific range as conductive particles, Electrode materials (ITO electrodes, Al vapor deposition electrodes, silver paste electrodes) that are usually provided in photoelectric conversion elements and tab wires that are normally used when connecting solar cells (SnAgCu solder-coated copper ribbons, solid copper ribbons) It can be seen that the two are connected while ensuring good reliability by the thermocompression treatment. Especially, it turns out that the case where an aspect-ratio is 3-50 and 50-100 is preferable.

  On the other hand, in the case of Comparative Example 1 using relatively hard spherical Ni particles among spherical conductive metal particles instead of flat flaky metal particles, the spherical Ni particles are difficult to deform during thermocompression bonding. This is presumably because the particles having a relatively large particle size existed and the particles having a small particle size could not contribute to the connection. Therefore, when ITO was used as the electrode material, the conduction reliability was evaluated as C. However, when an Ag paste electrode having a relatively soft electrode material was used, the silver Ni particles were embedded in the silver paste electrode side. Since the paste electrode side is deformed, it can be seen that there is no problem in conduction reliability. In addition, even when an aluminum paste electrode having a strong passive film formed on the surface is used, it can be seen that there is no problem in conduction reliability because the passive film can be broken during thermocompression bonding.

  In the case of Comparative Example 2 in which relatively soft spherical solder particles are used instead of flat flaky metal particles in the case of comparatively soft spherical solder particles, ITO itself deforms during thermocompression bonding, so ITO is used as an electrode material. When used, it can be seen that there is no problem in conduction reliability when a silver paste electrode is used. However, when an aluminum paste electrode having a strong passive film formed on the surface is used, it can be seen that the passive film cannot be broken during thermocompression bonding, and there is a problem in conduction reliability.

  The solar cell module of the present invention uses a connection conductive adhesive film as a bonding material between an electrode and a tab wire, and further, as conductive particles to be blended therein, at least 50% by mass is 1-50 μm long diameter, 5 μm or less. Flaky metal particles having an aspect ratio of 3 to 150 in thickness are used. Therefore, good connection reliability can be ensured regardless of the presence or absence of surface irregularities on the electrodes of the solar battery cells. Moreover, this flaky metal particle has hardness higher than a surface electrode and a tab wire. Therefore, even when Al paste or Al deposited film is used to form these electrodes, the surface passivation film of aluminum can be destroyed during the thermocompression treatment, and good connection reliability can be obtained. Can be secured.

DESCRIPTION OF SYMBOLS 10 Photoelectric conversion element 21 1st electrode 22, 24 Finger electrode 23 2nd electrode 30, 34 Tab wire | line 32 Thin film type photovoltaic cell 38 Base material 40 Conductive adhesive layer 50 Solar cell 100 Solar cell module 200 Metal frame 201 Translucent Surface protective material 202 Back surface protective material 203 Translucent sealing material

Claims (6)

A conductive adhesive for connecting a surface electrode of at least one solar battery cell of a solar battery module in which a plurality of solar battery cells are connected in series to a tab wire, wherein conductive particles are dispersed in a binder resin composition. And
50% by mass or more of the conductive particles have a major axis of 1 to 20 μm, a thickness of 3 μm or less and an aspect ratio (= major axis / thickness) of 3 to 50, or a major axis of 20 to 40 μm and an aspect of 50 to 100 A conductive adhesive having a ratio (= major axis / thickness), and the conductive particles are flaky nickel particles having a hardness higher than that of a surface electrode and a tab wire of a solar battery cell. A conductive adhesive for connecting a surface electrode of at least one solar battery cell of a solar battery module in which a plurality of solar battery cells are connected in series to a tab wire, wherein conductive particles are dispersed in a binder resin composition. And
50% by mass or more of the conductive particles have a major axis of 1 to 20 μm, a thickness of 3 μm or less and an aspect ratio (= major axis / thickness) of 3 to 50, or a major axis of 20 to 40 μm and an aspect of 50 to 100 Ratio (= major axis / thickness) and the conductive particles are higher than the surface electrode and tab wire of the solar cell so that the passive film of the surface electrode is broken by the thermocompression treatment and bites into the tab wire. A conductive adhesive, characterized by being flaky nickel particles having hardness. The conductive adhesive according to claim 1 or 2 , wherein the binder resin composition contains a thermosetting epoxy resin and an imidazole-based latent curing agent. The conductive adhesive according to claim 3 , wherein the thermosetting epoxy resin is a compound having an epoxy equivalent of 100 to 4000 and having two or more epoxy groups in the molecule. Furthermore, claim an average particle size of the small spherical conductive particles than the major diameter of it and flaky nickel particles is 1 to 10 [mu] m, containing at 0.01 times the rate of the amount of flaky nickel particles (parts by weight) 1-4 . The electrically conductive adhesive in any one of 1-4 . When the conductive adhesive is a paste, the viscosity at 25 ° C. measured with a cone plate viscometer is 50 to 200 Pa · s. When the conductive adhesive is a film, the minimum melt viscosity measured with a cone plate viscometer is 1 × 10 ^{It is} 2-1 * 10 < ⁵ > Pa * s, The electrically conductive adhesive in any one of Claims 1-5 .

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