WO2013061923A1

WO2013061923A1 - Conductive adhesive, solar cell module, and method for manufacturing solar cell module

Info

Publication number: WO2013061923A1
Application number: PCT/JP2012/077238
Authority: WO
Inventors: 一俊鈴木
Original assignee: デクセリアルズ株式会社
Priority date: 2011-10-28
Filing date: 2012-10-22
Publication date: 2013-05-02
Also published as: KR20140098090A; JP5960408B2; JP2013098230A

Abstract

Provided are: a conductive adhesive which is capable of achieving excellent connection reliability by ensuring high adhesive power; and a solar cell module which is capable of achieving high power generation efficiency by connecting electrodes of a solar cell and tab wires using this conductive adhesive. This conductive adhesive is obtained by dispersing conductive particles in a binder which contains a radical polymerization initiator, a (meth)acrylate that does not contain a phosphoric acid group or a phosphoric acid ester group, and a (meth)acrylate that contains a phosphoric acid group or a phosphoric acid ester group. The radical polymerization initiator has a 1-minute half-life temperature of 110-140°C. The (meth)acrylate that contains a phosphoric acid group or a phosphoric acid ester group is contained in an amount of 0.1-5 parts by mass per 54 parts by mass of the (meth)acrylate that does not contain a phosphoric acid group or a phosphoric acid ester group.

Description

Conductive adhesive, solar cell module, and method for manufacturing solar cell module

The present invention relates to a conductive adhesive in which conductive particles are dispersed, a solar battery module formed by connecting an electrode of a solar battery cell and a tab wire using the conductive adhesive, and manufacture of the solar battery module. Regarding the method. This application claims priority on the basis of Japanese Patent Application No. 2011-237362 filed on Oct. 28, 2011 in Japan, and is incorporated herein by reference. Is done.

In the solar cell module, a conductive adhesive film that can be connected by thermocompression treatment at a relatively low temperature is used for connection between the solar cell electrode and the tab wire. One end of the tab wire is connected to the front surface electrode of one solar battery cell, and the other end is connected to the back surface electrode of another adjacent solar battery cell, thereby connecting the solar battery cells in series.

As a resin contained in a binder (insulating adhesive composition) of a conductive adhesive applied to such a solar cell module, an epoxy resin has been widely used conventionally. However, in recent years, an acrylic resin (acrylate) is widely used instead of the epoxy resin (see Patent Document 1). By using the acrylic resin, the conductive adhesive can be pressure-bonded at a lower temperature, and the tact time can be shortened, and the advantage that metal corrosion can be suppressed can be obtained.

JP 2011-66448 A

However, the conductive adhesive containing an acrylic resin generally tends to have a low adhesion to an object to be bonded. For this reason, there is a possibility that excellent connection reliability cannot be obtained with a conductive adhesive containing an acrylic resin. In addition, in the case of conventional conductive adhesives, there are cases in which yield is improved by reducing cell damage by low-temperature mounting. However, the tact time required for adhesion is 15 to 20 seconds, and there is a problem that it takes 3 to 4 times as long as the method using solder.

The present invention has been proposed in view of such a conventional situation, and secures high adhesive force in a conductive adhesive containing an acrylic resin in a binder and has excellent connection reliability in a short time at low temperature. It is an object of the present invention to provide a conductive adhesive capable of obtaining the above. And this invention aims at providing the solar cell module which can connect the electrode and tab wire of a photovoltaic cell using this conductive adhesive, and can obtain high electric power generation efficiency.

In order to solve the above-described problem, the conductive adhesive according to the present invention includes a surface electrode of one solar battery cell, a back electrode of another solar battery cell adjacent to the one solar battery cell, a tab wire, In a conductive adhesive for electrically connecting a radical polymerization initiator, a (meth) acrylate that does not contain a phosphate group or a phosphate ester group, and a phosphate group or a phosphate ester group (meta ) Conductive particles are dispersed in a binder containing acrylate, and the radical polymerization initiator has a one-minute half-life temperature of 110 to 140 ° C. and contains a phosphate group or a phosphate ester group (meth) The acrylate is characterized by being contained in an amount of 0.1 to 5 parts by mass with respect to 54 parts by mass of (meth) acrylate not containing a phosphate group or a phosphate ester group.

In order to solve the above-described problem, the solar cell module according to the present invention is such that the surface electrode of one solar cell and the back electrode of another solar cell adjacent to the one solar cell are conductive. Solar cell module electrically connected to a tab wire via a conductive adhesive, wherein the conductive adhesive does not contain a radical polymerization initiator and a phosphate group or a phosphate ester group (meth) acrylate And conductive particles are dispersed in a binder containing a phosphoric acid group or a (meth) acrylate containing a phosphoric acid ester group, and the one minute half-life temperature of the radical polymerization initiator is 110 to 140 ° C. The (meth) acrylate containing a phosphoric acid group or a phosphoric acid ester group is 0.1 to 5 mass based on 54 parts by mass of the (meth) acrylate not containing a phosphoric acid group or a phosphoric acid ester group. Characterized in that it is contained.

Moreover, in order to solve the subject mentioned above, the manufacturing method of the solar cell module which concerns on this invention is the surface electrode of one photovoltaic cell, and the back surface electrode of the other photovoltaic cell adjacent to one photovoltaic cell. In the method for manufacturing a solar cell module in which the conductive adhesive is electrically connected with the tab wire via the conductive adhesive, the conductive adhesive does not contain a radical polymerization initiator and a phosphate group or a phosphate ester group (meta ) And conductive particles are dispersed in a binder containing an acrylate and a (meth) acrylate containing a phosphate group or a phosphate ester group, and the half-life temperature of the radical polymerization initiator is 110 to 140 ° C. The (meth) acrylate containing a phosphate group or a phosphate ester group is based on 54 parts by mass of a (meth) acrylate that does not contain a phosphate group or a phosphate ester group. 0.1 to 5 are contained parts by mass, the tab lead, disposed on the surface electrode and the rear electrode through the conductive adhesive, wherein the hot-pressing pressure.

In the present invention, the conductive adhesive comprises a radical polymerization initiator, a (meth) acrylate that does not contain a phosphate group or a phosphate ester group, and a (meth) acrylate that contains a phosphate group or a phosphate ester group. Conductive particles are dispersed in the binder to be contained. The 1 minute half-life temperature of this radical polymerization initiator is 110 to 140 ° C. Further, the (meth) acrylate containing a phosphate group or a phosphate ester group is contained in an amount of 0.1 to 5 parts by mass with respect to 54 parts by mass of a (meth) acrylate not containing a phosphate group or a phosphate ester group. Yes. According to the conductive adhesive of the present invention thus adjusted, it is possible to provide a conductive adhesive that has a high adhesive force to an inorganic base material such as a metal while being an acrylic adhesive film. And the solar cell module which can exhibit the outstanding connection reliability and can obtain high electric power generation efficiency by using the conductive adhesive which acquired such high adhesive force can be provided.

Drawing 1 is a figure showing typically the conductive adhesive film which is an example of the product form of a conductive adhesive. FIG. 2 is a diagram illustrating a configuration example of the solar cell module. FIG. 3 is a schematic cross-sectional view of a solar battery cell.

Hereinafter, embodiments of the present invention (this embodiment) will be described in detail in the following order with reference to the drawings.
1. 1. Conductive adhesive 2. Manufacturing method of conductive adhesive Solar cell module 4. 4. Manufacturing method of solar cell module Example

<1. Conductive adhesive>
First, the conductive adhesive in the present embodiment will be described. The conductive adhesive in the present embodiment is obtained by dispersing conductive particles in a binder (insulating adhesive composition). This conductive adhesive is used as an adhesive for electrically connecting a surface electrode of one solar cell and a back electrode of another solar cell adjacent to this one solar cell with a tab wire. It is done.

In the conductive adhesive in the present embodiment, the binder contains a radical polymerization initiator, a (meth) acrylate that does not contain a phosphate group or a phosphate ester group, and a phosphate group or a phosphate ester group (meta ) Acrylate.

In the conductive adhesive in the present embodiment, the one minute half-life temperature of the radical polymerization initiator is 110 to 140 ° C., and particularly preferably 116 to 131 ° C. When the half-life temperature of the radical polymerization initiator is less than 110 ° C., the thermosetting reaction proceeds rapidly during the heat pressurization, so that the conductive particles are placed between the tab wire and the solar cell electrode. In this case, a so-called indentation failure that cannot be sufficiently crimped occurs. And when connecting the tab wire and the front electrode and the back electrode of the solar battery cell using a conductive adhesive containing a radical polymerization initiator having a 1 minute half-life temperature of less than 110 ° C., the obtained solar In the battery module, the connection becomes unstable, and the power generation efficiency is lowered as evidenced by the thermal shock test.

On the other hand, when the radical polymerization initiator has a high half-life temperature of 1 minute, the thermosetting reaction becomes slow.
For example, using a conductive adhesive containing a radical polymerization initiator whose half-life temperature exceeds 140 ° C. for 1 minute, the tab wire and the front and back electrodes of the solar cell are connected by thermal pressurization at a low temperature in a short time. In such a case, in the obtained solar cell module, the thermosetting reaction becomes insufficient, and the power generation efficiency decreases as proved by the thermal shock test.

In the conductive adhesive in the present embodiment, by adding a phosphoric acid group or a phosphoric ester group-containing (meth) acrylate, adhesion to an inorganic substrate such as a metal can be improved and the adhesive force can be increased. . The (meth) acrylate containing a phosphate group or a phosphate ester group is contained in an amount of 0.1 to 5 parts by mass with respect to 54 parts by mass of a (meth) acrylate not containing a phosphate group or a phosphate ester group. If it is less than 0.1 part by mass, the adhesion on the surface of an inorganic material such as metal cannot be secured. If it exceeds 5 parts by mass, the adhesive strength may decrease due to a decrease in the life of the conductive adhesive.

The radical polymerization initiator is preferably contained in an amount of 1 to 5 parts by mass with respect to 54 parts by mass of (meth) acrylate not containing a phosphate group or a phosphate ester group. If it is less than 1 part by mass, curing in a short time is insufficient and poor connection occurs. When the amount exceeds 5 parts by mass, the curing reaction is accelerated, so that the connection of the conductive particles becomes unstable.

The conductive adhesive preferably contains a film-forming resin, a thermoplastic elastomer, a silane coupling agent, an inorganic filler, and the like as other additive compositions. The shape of the conductive adhesive is not limited to the film shape, and may be a paste.

(Meth) acrylate containing no phosphate group or phosphate ester group is a curable resin having a radical functional group and cured by a radical polymerization initiator. (Meth) acrylates that do not contain phosphoric acid groups or phosphate ester groups are monofunctional (meth) acrylates, bifunctional (meth) acrylates, trifunctional (meth) acrylates, tetrafunctional (meth) acrylates, and many more than five functional groups. It is 1 type, or 2 or more types selected from functional (meth) acrylate.

Monofunctional (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) ) Acrylate, t-butyl (meth) acrylate, 2-methylbutyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, n-heptyl (meth) acrylate, 2-methylhexyl (meth) Acrylate, 2-ethylhexyl (meth) acrylate, 2-butylhexyl (meth) acrylate, isooctyl (meth) acrylate, isopentyl (meth) acrylate, isononyl (meth) acrylate, isodecyl (meth) acrylate, cyclohexyl ( Acrylate), benzyl (meth) acrylate, phenoxy (meth) acrylate, n-nonyl (meth) acrylate, n-decyl (meth) acrylate, lauryl (meth) acrylate, hexadecyl (meth) acrylate, stearyl (meth) acrylate, etc. Is mentioned.

Bifunctional (meth) acrylates include bisphenol F-EO modified di (meth) acrylate, bisphenol A-EO modified di (meth) acrylate, polypropylene glycol di (meth) acrylate, polyethylene glycol (meth) acrylate, and tricyclodecanedi. Examples include methylol di (meth) acrylate and dicyclopentadiene (meth) acrylate.

Trifunctional or higher (meth) acrylates include trimethylolpropane tri (meth) acrylate, trimethylolpropane PO-modified (meth) acrylate, isocyanuric acid EO-modified tri (meth) acrylate, tris (2-acryloyloxyethyl) isocyanurate Dipentaerythritol penta (meth) acrylate, pentaerythritol hexa (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetraacrylate, polyfunctional urethane (meth) acrylate, and the like.

These (meth) acrylates may be used alone or in combination of two or more.

In the conductive adhesive in the present embodiment, 10 to 30 parts by mass of trifunctional or higher acrylate (trifunctional acrylate (triacrylate) among 54 parts by mass of (meth) acrylate not containing a phosphate group or a phosphate ester group. ) And tetrafunctional or higher functional acrylates. According to the (meth) acrylate having three or more functional groups, the adhesiveness of the conductive adhesive can be increased because the adhesiveness of the cured resin can be improved by forming a crosslinked structure.

As the (meth) acrylate containing a phosphate group or a phosphate ester group, a monoester, a diester, a triester, or the like can be used. Examples of the (meth) acrylate containing a phosphoric acid group or a phosphate ester group include ethylene oxide-modified phenoxylated phosphoric acid (meth) acrylate, ethylene oxide-modified butoxylated phosphoric acid (meth) acrylate, ethylene oxide-modified octyloxylated phosphoric acid ( Examples thereof include meth) acrylate, ethylene oxide-modified phosphoric acid di (meth) acrylate, ethylene oxide-modified phosphoric acid tri (meth) acrylate, and the like. These may be used alone or in combination of two or more. By blending a phosphoric acid group or a phosphoric ester group-containing (meth) acrylate, the adhesion on the surface of an inorganic substance such as a metal can be improved.

As the radical polymerization initiator, a known one can be used, and among them, an organic peroxide is preferably used. Examples of the organic peroxide include benzoyl peroxide, lauroyl peroxide, butyl peroxide, benzyl peroxide, dilauroyl peroxide, dibutyl peroxide, benzyl peroxide, and peroxydicarbonate.

The film-forming resin corresponds to a high molecular weight resin having an average molecular weight of 10,000 or more, and preferably has an average molecular weight of about 10,000 to 80,000 from the viewpoint of film formation. As the film-forming resin, various resins such as an epoxy resin, a modified epoxy resin, a urethane resin, and a phenoxy resin can be used. Among them, a phenoxy resin is preferably used from the viewpoint of the film formation state, connection reliability, and the like. .

Thermoplastic elastomer is a so-called rubber component that softens and exhibits fluidity when heated and returns to a rubbery elastic body when cooled. Examples of the thermoplastic elastomer include rubber-based elastic bodies such as acrylic rubber (ACR), butadiene rubber (BR), and nitrile rubber (NBR), and hydrogenated styrene-based thermoplastic elastomer (SEBS). The thermoplastic elastomer can absorb internal stress at the time of connection and does not cause curing inhibition, so that high connection reliability can be provided. It is preferable that a thermoplastic elastomer is 30 mass parts or less with respect to 54 mass parts of (meth) acrylates which do not contain a phosphate group or a phosphate ester group. If the amount exceeds 30 parts by mass, there is a problem that the power generation efficiency decreases in the thermal shock test.

As the silane coupling agent, epoxy, amino, mercapto sulfide, ureido, etc. can be used. The adhesion at the interface between the organic material and the inorganic material can be improved by the silane coupling agent.

As the inorganic filler, silica, talc, titanium oxide, calcium carbonate, magnesium oxide and the like can be used. Depending on the content of the inorganic filler, the fluidity can be controlled and the particle capture rate can be improved.

Examples of the conductive particles that can be used include metal particles such as nickel, gold, and copper, and resin particles that are plated with gold. The average particle diameter of the conductive particles is preferably 1 to 20 μm, more preferably 2 to 10 μm, from the viewpoint of connection reliability. The average particle density of the conductive particles, the connection in terms of reliability and insulation reliability, preferably 500 to 50000 / mm ^2, more preferably 1,000 to 30,000 pieces / mm ^2.

Thus, the conductive adhesive in the present embodiment includes (meth) acrylate as a curable resin that does not contain a phosphate group or a phosphate ester group, and a radical polymerization initiator as a curing agent. And a (meth) acrylate containing a phosphate group or a phosphate ester group. The 1 minute half-life temperature of this radical polymerization initiator is 110 to 140 ° C. Further, the (meth) acrylate containing a phosphate group or a phosphate ester group is contained in an amount of 0.1 to 5 parts by mass with respect to 54 parts by mass of a (meth) acrylate not containing a phosphate group or a phosphate ester group. Yes. By blending phosphoric acid group or phosphoric ester group-containing (meth) acrylate at such a ratio, adhesion to an inorganic base material such as metal can be improved and the adhesive force can be increased.

As described above, according to the conductive adhesive in the present embodiment, it is possible to improve the adhesion to the metal surface such as the bus bar electrode while being an acrylic adhesive film. Accordingly, high adhesiveness to the metal surface can be obtained in the thermocompression treatment at a relatively low temperature of about 200 ° C. or less. For example, the tab wire and the bus bar electrode whose surface is made of Ag can be firmly connected through such a conductive adhesive, and high connection reliability can be obtained between the tab wire and the bus bar electrode. it can.

FIG. 1 is a diagram schematically showing a conductive adhesive film which is an example of a product form of a conductive adhesive in the present embodiment. The conductive adhesive film 20 is formed in a tape shape by laminating a conductive adhesive layer on a release substrate 21. The tape-like conductive adhesive film 20 is wound and laminated on the reel 22 so that the peeling base material 21 is on the outer peripheral side. There is no restriction | limiting in particular as the peeling base material 21, The above-mentioned PET, OPP, PMP, PTFE, etc. can be used.

Note that the conductive adhesive film 20 may have a configuration in which a transparent cover film is provided on the conductive adhesive layer. A tab wire may be used as the cover film to be attached on the conductive adhesive layer. By preliminarily laminating and integrating the tab wire and the conductive adhesive film 20, in actual use, the peeling base material 21 is peeled off, and the conductive adhesive layer of the conductive adhesive film 20 is placed on the surface electrode ( The tab wire and each electrode can be connected by sticking on the tab wire connecting portion of the bus bar electrode) and the back electrode.

<2. Method for producing conductive adhesive>
Next, a method for producing a conductive adhesive to which the present invention is applied will be described. Here, the manufacturing method of the electroconductive adhesive film in which the electroconductive adhesive was formed in the film form is demonstrated. The method for producing a conductive adhesive film in the present embodiment includes a coating step of applying a composition containing conductive particles in a binder composed of the above-described components on a release substrate, and a composition on the release substrate. And a drying step for drying.

In the coating step, a composition in which conductive particles are contained in a binder composed of the above-described components is prepared using an organic solvent, and this composition is coated on a release substrate using a bar coater, a coating apparatus, or the like. .

As the organic solvent, toluene, ethyl acetate, or a mixed solvent thereof, and other various organic solvents can be used. The release substrate is, for example, a laminate in which a release agent such as silicone is applied to a film such as PET (Poly Ethylene Terephthalate), OPP (Oriented Polypropylene), PMP (Poly-4-methlpentene-1), PTFE (Polytetrafluoroethylene), etc. It consists of a structure, prevents the composition from drying, and maintains the film shape of the composition.

In the drying step, the composition on the release substrate is dried by a device such as a heat oven or a heat drying device. Thereby, the conductive adhesive film which is the conductive adhesive formed in the film form can be obtained.

<3. Solar cell module>
Next, the solar cell module in this Embodiment is demonstrated. The solar cell module in this embodiment includes a single crystal silicon photoelectric conversion device, a crystalline silicon solar cell module using a polycrystalline photoelectric conversion device, a cell made of amorphous silicon, microcrystalline silicon, and amorphous as a photoelectric conversion device. This is a thin film silicon solar cell using a photoelectric conversion element in which cells made of silicon germanium are stacked.

As shown in FIG. 2, the solar cell module 1 includes a matrix 5 in which a plurality of solar cells 2 are connected in series by tab wires 3 serving as interconnectors, and a plurality of strings 4 are arranged. In the solar cell module 1, the matrix 5 is sandwiched between the sheets 6 of the sealing adhesive, and together with the front cover 7 provided on the light receiving surface side as the protective base material and the back sheet 8 provided on the back surface side. It is formed by laminating and attaching a metal frame 9 such as aluminum around it.

As the sealing adhesive, for example, a translucent sealing material such as ethylene vinyl alcohol resin (EVA) is used. Moreover, as the surface cover 7, for example, a light-transmitting material such as glass or light-transmitting plastic is used. Further, as the back sheet 8, a laminated body in which glass or aluminum foil is sandwiched between resin films is used.

Each solar cell 2 of the solar cell module 1 has a photoelectric conversion element 10 made of a silicon substrate, as shown in FIG. The photoelectric conversion element 10 is provided with a bus bar electrode 11 serving as a surface electrode on the light receiving surface side and a finger electrode 12 that is a collecting electrode formed in a direction substantially orthogonal to the bus bar electrode 11. The photoelectric conversion element 10 is provided with a back electrode 13 made of Al, Ag, or the like on the back side opposite to the light receiving surface.

The solar battery cell 2 is electrically connected to the bus bar electrode 11 as the front electrode and the back electrode 13 of the adjacent solar battery cell 2 by the tab wire 3, thereby connecting the strings 4 connected in series. Constitute. The tab wire 3 is connected to the bus bar electrode 11 and the back electrode 13 by the conductive adhesive film 20.

The tab wire 3 can use the tab wire used in the conventional solar cell module. The tab wire 3 is formed by using, for example, a ribbon-like copper foil having a thickness of 50 to 300 μm and performing gold plating, silver plating, tin plating, solder plating, or the like as necessary. Moreover, you may use what laminated | stacked the conductive adhesive film previously mentioned on the tab wire 3 previously.

The bus bar electrode 11 is formed by applying a metal paste such as Ag, Cu or Al and heating. The bus bar electrode 11 formed on the light receiving surface of the solar battery cell 2 is formed in a line shape with a width of 1 mm, for example, in order to reduce the area that blocks incident light and suppress shadow loss. The number of bus bar electrodes 11 can be appropriately set in consideration of the size and resistance of the solar battery cell 2.

The finger electrode 12 is made of a metal material such as Ag, Cu, or Al, and is formed over substantially the entire light receiving surface of the solar cell 2 by intersecting with the bus bar electrode 11 by the same method as the bus bar electrode 11. . The finger electrodes 12 are formed with lines having a width of about 100 μm, for example, at a predetermined interval, for example, every 2 mm.

The back electrode 13 is formed of an aluminum electrode on the back surface of the solar cell 2 by, for example, screen printing or sputtering.

In the present embodiment, the solar battery cell is not limited to such a configuration of the solar battery cell 2. For example, the bus bar electrode is not necessarily provided. In such a solar cell having a bus barless structure, the current of the finger electrode is collected by a tab line intersecting the finger electrode. In addition, an opening may be formed in the Al back electrode to such an extent that it does not cause poor connection with the tab wire, thereby securing adhesive strength. That is, the conductive adhesive in the present embodiment can be used for a solar cell having a bus bar-less structure in which no bus bar electrode is present, and can exhibit an excellent adhesive force.

<4. Manufacturing method of solar cell module>
Next, a method for manufacturing the solar cell module 1 will be described with reference to FIGS. The manufacturing method of the solar cell module 1 in the present embodiment includes a bus bar electrode 11 (surface electrode) made of Ag or the like of one solar cell 2 and another solar cell 2 adjacent to the one solar cell 2. The back electrode 13 is electrically connected with the tab wire 3 through the conductive adhesive film 20. The tab wire 3 is disposed on the front bus bar electrode 11 and the back electrode 13 through the conductive adhesive film 20. And the solar cell module 1 is manufactured by crimping and connecting the tab wire 3 and each electrode by thermal pressurization.

Specifically, first, the finger electrode 12 and the bus bar electrode 11 are formed on the surface of the photoelectric conversion element 10 by applying and baking Ag paste, and the back electrode 13 is formed on the connection portion of the tab wire 3 by Al screen printing on the back surface. It forms and the photovoltaic cell 2 is produced.

Next, the conductive adhesive film 20 is stuck to the bus bar electrode 11 on the surface of the photoelectric conversion element 10 and the back electrode 13 on the back surface, and the tab wire 3 is disposed on the conductive adhesive film 20, and predetermined heat and pressure conditions The tab wire 3 is temporarily crimped at (for example, 70 ° C., 0.5 MPa, 1 second).

Then, the tab wire 3 is finally pressure-bonded under predetermined heat and pressure conditions (for example, 140 to 200 ° C., 0.5 MPa to 3 MPa, 3 to 10 seconds), and the tab wire 3 and the bus bar electrode 11 and the back electrode 13 are electrically connected. Connect to. At this time, the tab wire 3 is mechanically firmly connected to the bus bar electrode 11 because the binder of the conductive adhesive film 20 has good adhesiveness with the bus bar electrode 11 formed of Ag paste. The tab wire 3 is electrically connected to the back electrode 13.

The matrix 5 to which the solar cells 2 are connected is sandwiched between sheets 6 of a sealing adhesive and laminated together with a front cover 7 provided on the light receiving surface side and a back sheet 8 provided on the back surface side as protective materials. Thus, the solar cell module 1 is manufactured.

Thus, in the manufacturing method of the solar cell module 1, the tab wire 3 and the bus bar electrode 11 and the back electrode 13 made of Ag on the surface are connected using the conductive adhesive film. The binder of the conductive adhesive film contains a radical polymerization initiator, a (meth) acrylate that does not contain a phosphate group or a phosphate ester group, and a (meth) acrylate that contains a phosphate group or a phosphate ester group. . The 1 minute half-life temperature of this radical polymerization initiator is 110 to 140 ° C. Further, the (meth) acrylate containing a phosphate group or a phosphate ester group is contained in an amount of 0.1 to 5 parts by mass with respect to 54 parts by mass of a (meth) acrylate not containing a phosphate group or a phosphate ester group. Yes.

In the manufacturing method of the solar cell module 1, the adhesiveness with respect to the bus-bar electrode 11 which has metal surfaces, such as Ag, can be improved by using the conductive adhesive film 20 which consists of such a component. That is, the tab wire 3 and each electrode can be firmly connected by a relatively low thermocompression treatment of about 200 ° C. or less when pressed by the heating and pressing head, and the manufactured solar cell module 1 has high connection reliability. Sex can be obtained.

In addition, the manufacturing method of a solar cell module is not limited to such a method. For example, the front electrode and the tab wire of one solar cell and the back electrode and the tab wire of the other solar cell are temporarily fixed with the above-described conductive adhesive film interposed, and the upper and lower surfaces of the solar cell are fixed. A sealing material and a protective base material are laminated in order, and laminated and pressure-bonded with a laminating apparatus (decompression laminator) from the upper surface of the protective base material, the sealing material is cured, and the front surface electrode and the tab wire and the back surface electrode and the tab wire are bonded. You may connect.

<5. Example>
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these Examples.

Example 1
A conductive adhesive film comprising conductive particles in a binder was produced. The binder was composed of the following components.

That is, 20 parts by mass of phenoxy resin (FX280, manufactured by Toto Kasei Co., Ltd.) was used as the film forming resin. As rubber components, 5 parts by mass of acrylic rubber (SG series, manufactured by Nagase Chemtex Co., Ltd.) and 15 parts by mass of hydrogenated styrene-based thermoplastic elastomer (SEBS) (Tuftec series, manufactured by Asahi Kasei Chemicals Co., Ltd.) were used.

As the acrylate, 5 parts by mass of epoxy acrylate (V # 540, manufactured by Osaka Organic Chemical Industry Co., Ltd.), 24 parts by mass of dimethacrylate (NK ester DCP, manufactured by Shin Nakamura Chemical Co., Ltd.), trifunctional acrylate, that is, triacrylate (NK ester A9300) , Shin-Nakamura Chemical Co., Ltd.) 25 parts by mass and phosphate ester group-containing acrylate (PM series, Nippon Kayaku Co., Ltd.) 2 parts by mass were used.

As a silane coupling agent, 1 part by mass of methacryloxysilane (KBE503, manufactured by Shin-Etsu Chemical Co., Ltd.) was used. As a radical polymerization initiator (organic peroxide), 3 parts by mass of lauroyl peroxide (Perroyl L, manufactured by NOF Corporation) having an organic peroxide 1-minute half-life temperature of 116 ° C. was used.

A conductive adhesive was obtained by dispersing 15 parts by mass of Ni powder (manufactured by Bahrainco) having an average particle size of 10 μm as conductive particles in a binder composed of these components. This conductive adhesive was applied onto a release substrate and dried to produce a conductive adhesive film.

(Example 2)
Instead of the radical polymerization initiator of Example 1, 3 parts by weight of benzoyl peroxide (Nyper BMT-K40, manufactured by NOF Corporation) having an organic peroxide 1-minute half-life temperature of 131 ° C. was used as the radical polymerization initiator. A conductive adhesive film was produced in the same manner as in Example 1 except that.

(Example 3)
The phosphate ester group-containing acrylate of Example 1 (PM series, manufactured by Nippon Kayaku Co., Ltd.) was 0.1 mass part. Further, in place of the radical polymerization initiator of Example 1, as a radical polymerization initiator, 3 parts by mass of benzoyl peroxide (Nyper BMT-K40, manufactured by NOF Corporation) having an organic peroxide 1-minute half-life temperature of 131 ° C. A conductive adhesive film was produced in the same manner as in Example 1 except that was used.

(Example 4)
3 parts by mass of the phosphate group-containing acrylate of Example 1 (PM series, manufactured by Nippon Kayaku Co., Ltd.) was used. Further, in place of the radical polymerization initiator of Example 1, as a radical polymerization initiator, 3 parts by mass of benzoyl peroxide (Nyper BMT-K40, manufactured by NOF Corporation) having an organic peroxide 1-minute half-life temperature of 131 ° C. Was used. Other than that was carried out similarly to Example 1, and produced the electroconductive adhesive film.

(Example 5)
Instead of the radical polymerization initiator of Example 1, 1 part by weight of benzoyl peroxide (Nyper BMT-K40, manufactured by NOF Corporation) having an organic peroxide 1-minute half-life temperature of 131 ° C. was used as the radical polymerization initiator. A conductive adhesive film was produced in the same manner as in Example 1 except that.

(Example 6)
Instead of the radical polymerization initiator of Example 1, 5 parts by mass of benzoyl peroxide (Niper BMT-K40, manufactured by NOF Corporation) having an organic peroxide 1-minute half-life temperature of 131 ° C. was used as the radical polymerization initiator. A conductive adhesive film was produced in the same manner as in Example 1 except that.

(Example 7)
The epoxy acrylate of Example 1 (V # 540, manufactured by Osaka Organic Chemical Co., Ltd.) was 4 parts by mass, and dimethacrylate (NK ester DCP, manufactured by Shin Nakamura Chemical Co., Ltd.) was 20 parts by mass. Further, 30 parts by mass of the triacrylate of Example 1 (NK ester A9300, manufactured by Shin-Nakamura Chemical Co., Ltd.) was used. Further, in place of the radical polymerization initiator of Example 1, as a radical polymerization initiator, 3 parts by mass of benzoyl peroxide (Nyper BMT-K40, manufactured by NOF Corporation) having an organic peroxide 1-minute half-life temperature of 131 ° C. Was used. Other than that was carried out similarly to Example 1, and produced the electroconductive adhesive film.

(Example 8)
The epoxy acrylate of Example 1 (V # 540, Osaka Organic Chemical Industries, Ltd.) was 14 parts by mass, and dimethacrylate (NK ester DCP, Shin-Nakamura Chemical Co., Ltd.) was 30 parts by mass. The triacrylate of Example 1 (NK ester A9300, manufactured by Shin-Nakamura Chemical Co., Ltd.) was 10 parts by mass. Further, in place of the radical polymerization initiator of Example 1, as a radical polymerization initiator, 3 parts by mass of benzoyl peroxide (Nyper BMT-K40, manufactured by NOF Corporation) having an organic peroxide 1-minute half-life temperature of 131 ° C. Was used. Other than that was carried out similarly to Example 1, and produced the electroconductive adhesive film.

Example 9
Instead of the conductive particles of Example 1, 5 parts by mass of substituted plating silver-coated copper powder having an average particle size of 10 μm was used as the conductive particles. In the production of this substitution plating silver coat copper powder, the copper fine powder obtained by further mechanically pulverizing the atomized copper powder obtained by a so-called atomizing method was used. In addition, at the time of mechanical grinding | pulverization, it is guessed that the fatty acid is added in order to prevent the coarsening by aggregation of copper powder. Specifically, flake copper fine powder (model number: AFS-Cu 7 μm) manufactured by Nippon Atomizing Co., Ltd. was used. The flake copper fine powder had a weight cumulative particle diameter D50 of 7.9 μm as measured by a laser diffraction scattering particle size distribution measurement method.

The 500 g of the flaky copper fine powder was heat-treated in the atmosphere at a temperature of 250 ° C. for 5 minutes, and then the oxidized copper fine powder was coarsely crushed in a mortar. 500 g of coarsely pulverized copper fine powder was added to 1000 ml of 1% potassium hydroxide aqueous solution and stirred for 20 minutes, followed by primary decantation treatment, and further 1000 ml of pure water was added and stirred for several minutes.

Next, secondary decantation treatment was performed, and 2500 ml of sulfuric acid aqueous solution having a sulfuric acid concentration of 15 g / L was added and stirred for 30 minutes. Further, the acid washing with the sulfuric acid aqueous solution was repeated once more. Further, tertiary decantation treatment was performed, 2500 ml of pure water was added, and the mixture was stirred for several minutes. Then, a quaternary decantation treatment was performed, followed by filtration washing and suction dehydration to separate the flaky copper fine powder from the solution. The flaky copper fine powder was dried at a temperature of 90 ° C. for 2 hours.

To this dried flaky copper fine powder, 2500 ml of sulfuric acid aqueous solution having a sulfuric acid concentration of 7.5 g / L was added and stirred for 30 minutes. Subsequently, a fifth decantation treatment was performed, 2500 ml of pure water was added, and the mixture was stirred for several minutes.

Further, a sixth decantation treatment was performed, and 2500 ml of a 1% sodium potassium tartrate solution was added and stirred for several minutes to form a copper slurry. Dilute sulfuric acid or potassium hydroxide solution was added to the copper slurry to adjust the pH of the copper slurry to 3.5 to 4.5.

Substitution reaction treatment and reduction while adding silver nitrate ammonia solution 1000ml (added 87.5g of silver nitrate to water and adding ammonia water to 1000ml) to pH adjusted copper slurry slowly over 30 minutes. The reaction treatment was performed, and the mixture was further stirred for 30 minutes to obtain silver-plated copper fine powder.

Thereafter, the seventh decantation treatment was performed, 3500 ml of pure water was added, and the mixture was stirred for several minutes. Further, an eighth decantation treatment was performed, 3500 ml of pure water was added, and the mixture was stirred for several minutes. Then, the silver-plated copper fine powder and the solution were separated by filtration washing and suction dehydration, and the silver-plated copper fine powder was dried at a temperature of 90 ° C. for 2 hours.

The dried silver-plated copper fine powder (500 g) was placed in a tubular furnace and heat-treated at 200 ° C. for 30 minutes in a reducing atmosphere under a hydrogen stream (3.0 to 3.5 l / min). The heat-treated silver-plated copper fine powder was pulverized in a mortar. 500 g of heat-treated silver-plated copper fine powder was dispersed in 1000 ml of 0.5% isopropyl alcohol stearate solution and stirred for 30 minutes.

Then, the heat-treated stearic acid-coated silver-plated copper fine powder and the solution are separated by filtration, washing and dehydrating, and the heat-treated stearic acid-coated silver-plated copper fine powder is dried at a temperature of 90 ° C. for 2 hours and heat-treated. A fine powder of stearic acid-coated silver-plated copper (displacement-plated silver-coated copper powder) was obtained (see JP 2010-174411 A).

Further, in Example 9, instead of the radical polymerization initiator of Example 1, a benzoyl peroxide (Nyper BMT-K40, NOF Corporation) having an organic peroxide 1-minute half-life temperature of 131 ° C. was used as a radical polymerization initiator. 3 parts by mass were used. Other than that was carried out similarly to Example 1, and produced the electroconductive adhesive film.

(Comparative Example 1)
The triacrylate of Example 1 (NK ester A9300, manufactured by Shin-Nakamura Chemical Co., Ltd.) was 15 parts by mass. Further, in place of the radical polymerization initiator of Example 1, t-butyl peroxyneodecanoate (perbutyl ND, manufactured by NOF Corporation) having an organic peroxide 1-minute half-life temperature of 104 ° C. was used as a radical polymerization initiator. 3 parts by weight were used. Other than that was carried out similarly to Example 1, and produced the electroconductive adhesive film.

(Comparative Example 2)
In place of the radical polymerization initiator of Comparative Example 1, 1,1-di-t-butylperoxy-2-methylcyclohexane (Perhexa MC, JP) having a one minute half-life temperature of 142 ° C. as an organic peroxide was used as a radical polymerization initiator. A conductive adhesive film was produced in the same manner as in Comparative Example 1 except that 3 parts by mass of Yurai Co., Ltd. was used.

(Comparative Example 3)
The phosphate ester group-containing acrylate was not contained. Further, in place of the radical polymerization initiator of Comparative Example 1, 3 parts by mass of benzoyl peroxide (Nyper BMT-K40, manufactured by NOF Corporation) having an organic peroxide 1-minute half-life temperature of 131 ° C. as a radical polymerization initiator Was used. Other than that was carried out similarly to the comparative example 1, and produced the electroconductive adhesive film.

(Comparative Example 4)
The phosphate group-containing acrylate of Comparative Example 1 (PM series, manufactured by Nippon Kayaku Co., Ltd.) was 6 parts by mass. Further, in place of the radical polymerization initiator of Comparative Example 1, 3 parts by mass of benzoyl peroxide (Nyper BMT-K40, manufactured by NOF Corporation) having an organic peroxide 1-minute half-life temperature of 131 ° C. as a radical polymerization initiator Was used. Other than that was carried out similarly to the comparative example 1, and produced the electroconductive adhesive film.

(Comparative Example 5)
The phosphate ester group-containing acrylate was not contained. Further, 2 parts by mass of phosphate ester (LB-58, bis (2 ethylhexyl) phosphonate, manufactured by Johoku Chemical Co., Ltd.) was added as an additive. Further, in place of the radical polymerization initiator of Comparative Example 1, 3 parts by mass of benzoyl peroxide (Nyper BMT-K40, manufactured by NOF Corporation) having an organic peroxide 1-minute half-life temperature of 131 ° C. as a radical polymerization initiator Was used. Other than that was carried out similarly to the comparative example 1, and produced the electroconductive adhesive film.

<Measurement of adhesive strength>
The conductive adhesive films of Examples 1 to 7 and Comparative Examples 1 to 5 were formed using the 6-inch single crystal Si cell (dimensions: 15.6 cm × 15.6 cm, thickness: 180 μm) surface Ag bus bar electrode and Ag. The lead-free solder tab wire (width: 1.5 mm, thickness: 0.15 mm) was heat-pressed and adhered on the conductive adhesive film with a heat-pressure head. The heat and pressure conditions were 160 ° C., 1 MPa, and 5 seconds.

The adhesive strength of the conductive adhesive films of Examples 1 to 7 and Comparative Examples 1 to 5 was measured by this thermal pressing. Regarding the adhesive strength, the conductive adhesive film adhered on the bus bar electrode on the surface made of Ag was peeled in the direction of 90 degrees at a separation speed of 50 mm / min. Evaluation was made by measuring the force required for this peeling (peel strength, in accordance with JIS K6854-1). Table 1 shows the measurement results of peel strength as adhesive strength.

<Manufacture of solar cell modules, measurement of power generation efficiency>
The conductive adhesive films of Examples 1 to 9 and Comparative Examples 1 to 5 were respectively heated on a bus bar electrode and a back electrode provided in a solar cell (6-inch single crystal solar cell) with a heating temperature of 70 ° C. by a temporary attachment head. Temporary pasting was performed by heating and pressing at a pressure of 0.5 MPa for 1 second. Next, on the conductive adhesive film temporarily attached to the bus bar electrode and on the conductive adhesive film temporarily attached on the back electrode, both surfaces are flat, and the thickness is 0.20 mm covered with lead-free solder, A tab wire having a width of 1.5 mm was press-bonded. The conditions of the main pressure bonding were performed by heating and pressing at a heating temperature of 160 ° C. and a pressure of 1 MPa for 5 seconds. Next, from the light-receiving surface side, a surface cover made of glass, a first sheet made of ethylene vinyl acetate resin (EVA), a battery cell connected with tab wires, a second sheet made of ethylene vinyl acetate resin (EVA), After laminating in the order of the back sheets and applying a vacuum, the laminate was laminated at 150 ° C. for 3 minutes. Then, it was made to harden completely by heating at 150 degreeC for 30 minutes, and the solar cell module was produced.

The thermal shock test (−40 ° C. to 110 ° C.) for the initial power generation efficiency in this solar cell module conforms to JIS C8914 (crystalline solar cell module output measurement method) for the output (power generation efficiency) of the solar cell module after 1000 cycles. Measurement conditions: illuminance of 1000 W / m ² , temperature of 25 ° C., spectrum AM1.5G, using a solar simulator (solar simulator PVS1116i-M, manufactured by Nisshinbo Mechatronics Inc.). From the obtained measurement results, the rate of change (%) in power generation efficiency was calculated. When the rate of change was 97% or more, the power generation efficiency was evaluated as good (◯), 95% or more and less than 97% as slightly poor (Δ), and less than 95% as poor (×). The evaluation results are shown in Table 1.

The conductive adhesive films of Examples 1 to 9 contain a radical polymerization initiator having a half-life temperature of 116 to 131 ° C. for 1 minute, and 54 parts by mass of (meth) acrylate not containing a phosphate group or a phosphate ester group In contrast, 0.1 to 3 parts by mass of phosphoric acid group or phosphoric ester group-containing (meth) acrylate is contained.

As a result, in Examples 1 to 9, the adhesion to the bus bar electrode on the surface made of Ag can be improved and the adhesive force can be increased, and is comparable to the solder connection in the thermocompression treatment at a relatively low temperature of 160 ° C. It is considered that high adhesive strength was obtained in a short tact time. In the solar cell modules of Examples 1 to 9 manufactured using such a conductive adhesive, high connection reliability can be obtained between the tab wire, the front surface electrode, and the back surface electrode. It is considered that high power generation efficiency could be obtained in the thermal shock test because the connection by the conductive particles can be kept in a good state by appropriately selecting the polymerization initiator.

In Comparative Example 1, a radical polymerization initiator having a 1 minute half-life temperature of 104 ° C. was used as a curing agent to be included in the binder of the conductive adhesive film. Thereby, in thermocompression bonding, it is considered that the connection resistance is increased by hardening the binder before the conductive particles are sufficiently pressed between the tab wire and the solar cell electrode. Therefore, in the solar cell module manufactured using the conductive adhesive film of Comparative Example 1, since the connection state is unstable, it is considered that the power generation efficiency has decreased in the thermal shock test.

In Comparative Example 2, a radical polymerization initiator having a 1 minute half-life temperature of 142 ° C. was used as a curing agent to be included in the binder of the conductive adhesive film. As a result, although high adhesive strength was obtained in Comparative Example 2, in the solar cell module manufactured using such a conductive adhesive film, the cured state of the binder is insufficient, so that the electric power generated by the conductive particles is It is considered that the power generation efficiency has decreased due to the unstable connection state.

In Comparative Examples 3 and 5, since the phosphate group or phosphate ester group-containing (meth) acrylate is not contained, the effect of improving the adhesion to metal by the phosphate group or phosphate ester group-containing (meth) acrylate is obtained. Therefore, it is considered that the adhesive strength of the conductive adhesive film with respect to the surface electrode made of Ag could not be improved, and the adhesive strength was lowered.

And in the solar cell modules of Comparative Examples 3 and 5 manufactured using such a conductive adhesive film, it is considered that the power generation efficiency was lowered in the thermal shock test due to the tab wire peeling off.

In Comparative Example 4, 6 parts by mass of phosphoric acid group or phosphoric ester group-containing (meth) acrylate was contained in the binder of the conductive adhesive film. Thereby, it is thought that the adhesive strength of the conductive adhesive film was lowered by reducing the life of the conductive adhesive film. And in the solar cell module manufactured using such an electroconductive adhesive film, it is thought that electric power generation efficiency fell in the thermal shock test because adhesive strength fell and a tab wire peeled.

1 solar cell module, 2 solar cell, 3 tab line, 4 strings, 5 matrix, 6 sheet, 7 front cover, 8 back sheet, 9 metal frame, 10 photoelectric conversion element, 11 bus bar electrode, 12 finger electrode, 13 back surface Electrode, 20 conductive adhesive film, 21 release substrate, 22 reel

Claims

In a conductive adhesive for electrically connecting a surface electrode of one solar cell, a back electrode of another solar cell adjacent to the one solar cell, and a tab wire,
A radical polymerization initiator;
(Meth) acrylates that do not contain phosphate groups or phosphate ester groups;
Conductive particles are dispersed in a binder containing a (meth) acrylate containing a phosphate group or a phosphate ester group,
The one minute half-life temperature of the radical polymerization initiator is 110 to 140 ° C.,
The (meth) acrylate containing a phosphate group or a phosphate ester group is contained in an amount of 0.1 to 5 parts by mass with respect to 54 parts by mass of the (meth) acrylate not containing the phosphate group or the phosphate ester group. Conductive adhesive.
The conductive adhesive according to claim 1, wherein the radical polymerization initiator has a one-minute half-life temperature of 116 to 131 ° C.
The conductive adhesive according to claim 1 or 2, wherein the radical polymerization initiator is contained in an amount of 1 to 5 parts by mass with respect to 54 parts by mass of the (meth) acrylate not containing the phosphate group or the phosphate ester group.
The conductive adhesive according to any one of claims 1 to 3, wherein 10 to 30 parts by mass of 54 parts by mass of (meth) acrylate containing no phosphate group or phosphate ester group is a trifunctional acrylate. .
A solar cell module in which a surface electrode of one solar cell and a back electrode of another solar cell adjacent to the one solar cell are electrically connected to a tab wire via a conductive adhesive Because
The conductive adhesive is
A radical polymerization initiator;
(Meth) acrylates that do not contain phosphate groups or phosphate ester groups;
Conductive particles are dispersed in a binder containing a (meth) acrylate containing a phosphate group or a phosphate ester group,
The one minute half-life temperature of the radical polymerization initiator is 110 to 140 ° C.,
The (meth) acrylate containing a phosphate group or a phosphate ester group is contained in an amount of 0.1 to 5 parts by mass with respect to 54 parts by mass of the (meth) acrylate not containing the phosphate group or the phosphate ester group. Solar cell module.
Manufacture of a solar cell module in which a surface electrode of one solar cell and a back electrode of another solar cell adjacent to the one solar cell are electrically connected by a tab wire via a conductive adhesive In the method
The conductive adhesive is
A radical polymerization initiator;
(Meth) acrylates that do not contain phosphate groups or phosphate ester groups;
Conductive particles are dispersed in a binder containing a (meth) acrylate containing a phosphate group or a phosphate ester group,
The one minute half-life temperature of the radical polymerization initiator is 110 to 140 ° C.,
The (meth) acrylate containing a phosphate group or a phosphate ester group is contained in an amount of 0.1 to 5 parts by mass with respect to 54 parts by mass of the (meth) acrylate not containing the phosphate group or the phosphate ester group. And
The manufacturing method of the solar cell module which arrange | positions the said tab wire on the said surface electrode and the said back surface electrode through the said conductive adhesive, and heat-presses.