WO2012128386A1 - Solar cell module, manufacturing method for solar cell module, and conductive adhesive - Google Patents

Solar cell module, manufacturing method for solar cell module, and conductive adhesive Download PDF

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Publication number
WO2012128386A1
WO2012128386A1 PCT/JP2012/057790 JP2012057790W WO2012128386A1 WO 2012128386 A1 WO2012128386 A1 WO 2012128386A1 JP 2012057790 W JP2012057790 W JP 2012057790W WO 2012128386 A1 WO2012128386 A1 WO 2012128386A1
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WO
WIPO (PCT)
Prior art keywords
solder
conductive adhesive
solar cell
tab wire
outer layer
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Application number
PCT/JP2012/057790
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French (fr)
Japanese (ja)
Inventor
須賀　保博
Original Assignee
ソニーケミカル＆インフォメーションデバイス株式会社
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Application filed by ソニーケミカル＆インフォメーションデバイス株式会社 filed Critical ソニーケミカル＆インフォメーションデバイス株式会社
Priority to KR1020137027672A priority Critical patent/KR20140031225A/en
Publication of WO2012128386A1 publication Critical patent/WO2012128386A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
    • H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
    • H01L31/0512—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module made of a particular material or composition of materials
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Definitions

  • the present invention relates to a solar battery module in which a plurality of solar battery cells are connected by a tab wire, and in particular, a solar battery module for connecting an electrode of a solar battery cell and a tab wire via a conductive adhesive containing conductive particles.
  • the present invention relates to a method for manufacturing a solar cell module and a conductive adhesive.
  • a plurality of adjacent solar cells are connected by a tab wire serving as an interconnector.
  • One end side of the tab wire is connected to the front surface electrode of one solar battery cell, and the other end side is connected to the back surface electrode of the adjacent solar battery cell, thereby connecting the solar battery cells in series.
  • one surface of the tab wire is bonded to the surface electrode of one solar cell, and the other surface of the other end is bonded to the back electrode of the adjacent solar cell.
  • a bus bar electrode is formed on the light receiving surface and an Ag electrode is formed on the back surface connection portion by screen printing of silver paste.
  • Al electrodes and Ag electrodes are formed in regions other than the connection portion on the back surface of the solar battery cell.
  • the tab wire is formed by providing a solder coat layer on both sides of the ribbon-like copper foil.
  • the tab wire is a rectangular copper wire having a width of 1 to 3 mm obtained by slitting a copper foil rolled to a thickness of about 0.05 to 0.2 mm or rolling a copper wire into a flat plate shape. It is formed by performing solder plating, dip soldering, or the like.
  • connection between the solar battery cell and the tab wire is performed by disposing the tab wire on each electrode of the solar battery cell and applying heat and pressure with a heating bonder to melt and cool the solder formed on the tab wire surface ( Patent Document 1).
  • a conductive adhesive film that can be connected by thermocompression treatment at a relatively low temperature is used to connect the front and back electrodes of the solar battery cell and the tab wire (Patent Document 2).
  • a conductive adhesive film a film obtained by dispersing spherical or scaly conductive particles having an average particle size on the order of several ⁇ m in a thermosetting binder resin composition is used.
  • the conductive particles for example, metal particles such as nickel, gold, silver, and copper, or particles having resin particles as a core material and gold plating or the like are generally used.
  • the conductive adhesive film 50 is interposed between the front and back electrodes and the tab wire 51, and is then hot-pressed from above the tab wire 51 by a heating bonder.
  • the conductive adhesive film 50 allows the binder resin to flow out between the electrode and the tab wire 51, while the conductive resin 54 flows between the electrode 53 and the tab wire 51.
  • the binder resin is thermoset by being sandwiched and conducting between them. In this way, a string in which a plurality of solar cells 52 are connected in series by the tab wire 51 is formed.
  • the plurality of solar cells 52 in which the tab wire 51 and the front and back electrodes are connected using the conductive adhesive film 50 are made of a surface protecting material having translucency such as glass and translucent plastic, PET ( It is sealed with a light-transmitting sealing material such as ethylene vinyl acetate resin (EVA) between a back protective material made of a film such as Poly Ethylene Terephthalate).
  • a surface protecting material having translucency such as glass and translucent plastic, PET ( It is sealed with a light-transmitting sealing material such as ethylene vinyl acetate resin (EVA) between a back protective material made of a film such as Poly Ethylene Terephthalate).
  • EVA ethylene vinyl acetate resin
  • the conductive particles 54 are intended to conduct by contacting the tab wires 51 and the respective electrodes 53 on the front and back surfaces of the solar battery cell, so that the performance of the binder resin of the conductive adhesive film 50 is improved. Depends on the electrical connection reliability.
  • the solar cell module when the solar cell module is put into actual use, it may be repeatedly exposed to a high-temperature and high-humidity environment over a long period of time. As a result, the binder resin of the conductive adhesive film 50 is deteriorated and deteriorated. Contact between the conductive particles 54 and the tab wires 51 and the electrodes 53 is not maintained, and power generation efficiency may be reduced.
  • the present application can prevent separation of contact portions between the conductive particles, the tab wires, and the electrodes even when exposed to a high-temperature and high-humidity environment, regardless of the performance of the binder resin, and can maintain power generation efficiency. It aims at providing a solar cell module, a manufacturing method of a solar cell module, and a conductive adhesive.
  • a solar cell module includes a plurality of solar cells and conductive particles on electrodes formed on the surface of the solar cell and the back surface of the adjacent solar cell, respectively. And a tab wire for connecting a plurality of the solar cells, the conductive adhesive contains solder particles, and the solder particles are bonded to each other through a thermosetting conductive adhesive containing
  • the multilayer structure is composed of at least an inner layer and an outer layer, and the melting point of the solder constituting the inner layer is higher than the melting point of the solder constituting the outer layer.
  • the manufacturing method of the solar cell module which concerns on this invention arrange
  • the said solar cell A step of disposing the other end side of the tab wire via a thermosetting conductive adhesive containing conductive particles on the back electrode of the solar cell adjacent to the cell; Heat-pressing the back electrode and bonding the tab wire to the front electrode and the back electrode with the conductive adhesive, the conductive adhesive contains solder particles, and the solder particles
  • the multilayer structure is composed of at least an inner layer and an outer layer, and the melting point of the solder constituting the inner layer is higher than the melting point of the solder constituting the outer layer.
  • the conductive adhesive according to the present invention is interposed between the electrode formed in the solar battery cell and the tab wire connecting the plurality of solar battery cells, and is heated and pressed to thereby form the electrode.
  • a thermosetting binder resin and solder particles contained in the binder resin the solder particles having a multilayer structure composed of at least an inner layer and an outer layer.
  • the melting point of the solder constituting the inner layer is higher than the melting point of the solder constituting the outer layer.
  • the solder particles have a multilayer structure composed of at least an inner layer and an outer layer, and the melting point of the solder constituting the inner layer is higher than the melting point of the solder constituting the outer layer.
  • the outer layer is metal-bonded to the tab wire or the electrode of the solar battery cell, and the hard inner layer is sandwiched between the tab wire and the electrode. Therefore, even when the binder resin of the conductive adhesive is deteriorated, the electrical connection between the solder particles, the tab wire, and the electrode can be maintained.
  • FIG. 1 is an exploded perspective view showing a solar cell module.
  • FIG. 2 is a cross-sectional view showing strings of solar cells.
  • FIG. 3 is a plan view showing a back electrode and a connection part of the solar battery cell.
  • FIG. 4 is a cross-sectional view showing a conductive adhesive film.
  • FIG. 5 is a cross-sectional view showing tab wires and electrodes connected via solder particles.
  • FIG. 6 is a diagram showing a conductive adhesive film wound in a reel shape.
  • FIG. 7 is a diagram for explaining the embodiment.
  • FIG. 8 is a perspective view showing a conventional solar cell module.
  • FIG. 9 is a cross-sectional view showing a state where the tab wire and the electrode are connected via the conductive particles.
  • a solar cell module 1 to which the present invention is applied has a string 4 in which a plurality of solar cells 2 are connected in series by a tab wire 3 serving as an interconnector.
  • a matrix 5 in which a plurality of 4 are arranged is provided.
  • the solar cell module 1 is laminated together with the front cover 7 provided on the light receiving surface side and the back sheet 8 provided on the back surface side, with the matrix 5 sandwiched between the sealing adhesive sheets 6.
  • a metal frame 9 such as aluminum is attached to the periphery.
  • sealing adhesive for example, a translucent sealing material such as ethylene vinyl acetate resin (EVA) is used.
  • EVA ethylene vinyl acetate resin
  • surface cover 7 for example, a light-transmitting material such as glass or light-transmitting plastic is used.
  • back sheet 8 a laminated body in which glass or aluminum foil is sandwiched between resin films is used.
  • Each solar battery cell 2 of the solar battery module has a photoelectric conversion element 10.
  • the photoelectric conversion element 10 includes a single crystal silicon photoelectric conversion element, a crystalline silicon solar cell using a polycrystalline photoelectric conversion element, a thin film silicon solar cell made of amorphous silicon, a cell made of amorphous silicon, a microcrystalline silicon or an amorphous
  • Various photoelectric conversion elements 10 such as a multi-junction thin film silicon solar cell in which cells made of silicon germanium are stacked, a so-called compound thin film solar cell, an organic system, and a quantum dot type can be used.
  • the photoelectric conversion element 10 is provided with a finger electrode 12 for collecting electricity generated inside and a bus bar electrode 11 for collecting electricity of the finger electrode 12 on the light receiving surface side.
  • the bus bar electrode 11 and the finger electrode 12 are formed, for example, by applying an Ag paste on the surface to be a light receiving surface of the solar battery cell 2 by screen printing or the like and then baking it.
  • the finger electrode 12 has a plurality of lines having a width of about 50 to 200 ⁇ m, for example, approximately parallel to each other at a predetermined interval, for example, every 2 mm, over the entire light receiving surface.
  • the bus bar electrodes 11 are formed so as to be substantially orthogonal to the finger electrodes 12, and a plurality of bus bar electrodes 11 are formed according to the area of the solar battery cell 2.
  • the photoelectric conversion element 10 is provided with a back electrode 13 made of aluminum or silver on the back side opposite to the light receiving surface.
  • the back electrode 13 is formed of an electrode made of, for example, aluminum or silver on the back surface of the solar battery cell 2 by screen printing, sputtering, or the like.
  • the back electrode 13 has a tab wire connecting portion 14 to which the tab wire 3 is connected via a conductive adhesive film 17 described later.
  • the solar battery cell 2 is electrically connected to each bus bar electrode 11 formed on the surface by the tab wire 3 and the back electrode 13 of the adjacent solar battery cell 2, thereby connecting the strings connected in series. 4 is configured.
  • the tab wire 3 is connected to the bus bar electrode 11 and the back electrode 13 by a conductive adhesive film 17 described later.
  • the tab line 3 is a long conductive substrate that electrically connects each of the adjacent solar cells 2X, 2Y, and 2Z.
  • the tab wire 3 is substantially the same as the conductive adhesive film 17 by, for example, slitting a copper foil or aluminum foil rolled to a thickness of 50 to 300 ⁇ m, or rolling a thin metal wire such as copper or aluminum into a flat plate shape. A flat copper wire having a width of 1 to 3 mm is obtained.
  • the tab wire 3 is formed by applying gold plating, silver plating, tin plating, solder plating, or the like to the flat copper wire.
  • the conductive adhesive film 17 to which the present invention is applied is a thermosetting binder resin layer in which conductive particles are contained in the binder resin 22 at a high density.
  • the conductive particles contain solder particles 23 described in detail below.
  • the conductive adhesive film 17 preferably has a minimum melt viscosity of 100 to 100,000 Pa ⁇ s from the viewpoint of indentability. If the minimum melt viscosity of the conductive adhesive film 17 is too low, the resin flows in the process of low pressure bonding to main curing, and connection failure or protrusion to the cell light receiving surface is likely to occur, which causes a decrease in the light receiving rate.
  • the minimum melt viscosity can be measured while a sample is loaded in a predetermined amount of rotational viscometer and raised at a predetermined temperature increase rate.
  • solder particles 23 have multiple layers of solders having different melting points.
  • the solder particles 23 are composed of two layers of an inner layer 24 serving as a core and an outer layer 25 provided around the inner layer 24.
  • the inner layer 24 of the solder particles 23 shown in FIG. 5 is intended to establish conduction between the tab wire 3 and the electrodes 11 and 13 by being sandwiched between the tab wire 3 and the electrodes 11 and 13. Further, the outer layer 25 of the solder particles 23 shown in FIG. 5 ensures electrical connection reliability between the tab wire 3 and the electrodes 11 and 13 by metal bonding with the tab wire 3 and the electrodes 11 and 13. is there.
  • the melting point of the solder constituting the inner layer 24 is higher than the melting point of the solder constituting the outer layer 25. Therefore, the solder particles 23 are thermally bonded to the tab wires 3 and the electrodes 11 and 13 by thermally pressing the tab wires 3 onto the electrodes 11 and 13 via the conductive adhesive film 17, so that the inner layers 24 is sandwiched between the tab wire 3 and the electrodes 11 and 13 to achieve electrical connection therebetween.
  • the outer layer 25 is metal-bonded to the tab wire 3 and the electrodes 11 and 13, and the hard inner layer 24 is sandwiched between the tab wire 3 and the electrodes 11 and 13, thereby achieving conduction.
  • the solder particles 23 simply do not contact the tab wire 3 and the electrodes 11 and 13 to achieve conduction.
  • the conductive adhesive film 17 containing such solder particles 23 even when the binder resin 22 of the conductive adhesive film 17 deteriorates, the electrical connection between the solder particles 23, the tab wire 3, and the electrodes 11, 13 is achieved. Connection can be maintained.
  • the solder particles 23 are not limited to a two-layer structure as long as they have an outer layer 25 that is metal-bonded to the tab wire 3 and the electrodes 11 and 13 and an inner layer 24 that is sandwiched between the tab wire 3 and the electrodes 11 and 13. Three or more layers may be used. Even when the solder particles 23 are formed in three or more layers, the outer layer 25 that is metal-bonded to the tab wire 3 and the electrodes 11 and 13 is provided in the outermost layer, and is sandwiched between the tab wire 3 and the electrodes 11 and 13 inside thereof. An inner layer 24 is provided.
  • the solder particles 23 preferably have a melting point of the solder constituting the inner layer 24 higher than the curing temperature of the binder resin 22 of the conductive adhesive film 17. Thereby, even if the solder particles 23 are heated to the curing temperature of the binder resin 22 when the tab wire 3 is hot-pressed on the electrodes 11 and 13 via the conductive adhesive film 17, the inner layer 24 is melted. Therefore, the hardness can be maintained and the tab wire 3 and the electrodes 11 and 13 can be securely held. Further, since the inner layer 24 is hard, pressure is applied to the outer layer 25, the tab wire 3 and the electrodes 11 and 13 by a heating bonder to promote metal bonding.
  • the solder particles 23 preferably have a melting point of the solder constituting the outer layer 25 equal to or lower than the curing temperature of the binder resin 22 of the conductive adhesive film 17. As a result, the solder particles 23 are heated to the curing temperature of the binder resin 22 when the tab wire 3 is hot-pressed on the electrodes 11 and 13 via the conductive adhesive film 17, so that the outer layer 25 is melted. The tab wire 3 and the electrodes 11 and 13 can be surely metal-bonded.
  • the solder particles 23 can be manufactured by forming an inner layer 24 that becomes the core of the particles and forming an outer layer 25 that becomes a coating layer around the inner layer 24.
  • an atomizing method or the like which is the same method as used in the production of a normal solder powder, can be used.
  • a vapor deposition method, a sputtering method, an electroless plating method, a sol-gel method, or the like can be used. Since the outer layer 25 is formed so as to cover the entire inner layer 24, for example, when an evaporation method or a sputtering method is used, it is preferable that the inner layer 24 is also swung.
  • solder particles 23 use, for example, Sn—Ag—Cu solder (melting point: 220 ° C.) or Sn—Pb solder (melting point: 184 ° C.) as the solder constituting the inner layer, and the solder constituting the outer layer.
  • Sn—Bi solder (melting point: 141 ° C.) can be used.
  • the tab wire 3 is thermally pressed to the bus bar electrode 11 and the back electrode 13 at 180 ° C., so that the outer layer 25 melts and is metal-bonded to the tab wire 3 and the electrodes 11 and 13 and the inner layer 24 is tabbed. It is sandwiched between the wire 3 and the electrodes 11 and 13.
  • the solder particles 23 preferably have a melting point of solder constituting the inner layer higher than the thermal pressurization temperature of the tab wire 3, and a melting point of solder constituting the outer layer is equal to or lower than the thermal pressurization temperature of the tab wire 3. Preferably there is.
  • the particle size of the solder particles 23 can be used in the range of 1 to 100 ⁇ m, and the range of 20 to 50 ⁇ m can be preferably used.
  • the solar cell module 1 can improve the connection strength and electrical connection reliability of the tab wire 3 to the electrodes 11 and 13 in each solar cell 2 and is in a high temperature and high humidity environment under actual use.
  • the connection reliability of the tab wire 3 and the electrodes 11 and 13 through the solder particles 23 can be maintained even when repeatedly exposed to.
  • the composition of the binder resin 22 of the conductive adhesive film 17 is not particularly limited as long as it does not impair the above-described characteristics, but more preferably a film-forming resin, a liquid epoxy resin, a latent curing agent, a silane cup Contains a ring agent.
  • 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.
  • various resins such as an epoxy resin, a modified epoxy resin, a urethane resin, and a phenoxy resin can be used.
  • a phenoxy resin is preferably used from the viewpoint of the film formation state, connection reliability, and the like. .
  • the liquid epoxy resin is not particularly limited as long as it has fluidity at room temperature, and all commercially available epoxy resins can be used.
  • Specific examples of such epoxy resins include naphthalene type epoxy resins, biphenyl type epoxy resins, phenol novolac type epoxy resins, bisphenol type epoxy resins, stilbene type epoxy resins, triphenolmethane type epoxy resins, phenol aralkyl type epoxy resins.
  • Resins, naphthol type epoxy resins, dicyclopentadiene type epoxy resins, triphenylmethane type epoxy resins, and the like can be used. These may be used alone or in combination of two or more. Moreover, you may use it combining suitably with other organic resins, such as an acrylic resin.
  • the latent curing agent various curing agents such as a heat curing type and a UV curing type can be used.
  • the latent curing agent does not normally react but is activated by some trigger and starts the reaction.
  • the trigger includes heat, light, pressurization, etc., and can be selected and used depending on the application.
  • a thermosetting latent curing agent is suitably used, and the main curing is performed by heating and pressing the bus bar electrode 11 and the back electrode 13.
  • a latent curing agent composed of imidazoles, amines, sulfonium salts, onium salts and the like can be used.
  • silane coupling agent epoxy, amino, mercapto sulfide, ureido, etc. can be used.
  • an epoxy-type silane coupling agent is used preferably. Thereby, the adhesiveness in the interface of an organic material and an inorganic material can be improved.
  • an inorganic filler as another additive composition.
  • an inorganic filler silica, talc, titanium oxide, calcium carbonate, magnesium oxide and the like can be used, and the kind of the inorganic filler is not particularly limited.
  • FIG. 6 is a diagram schematically showing an example of a product form of the conductive adhesive film 17.
  • the conductive adhesive film 17 is formed in a tape shape by laminating a binder resin 22 on a peeling substrate 27. This tape-like conductive adhesive film is wound and laminated on the reel 26 so that the peeling substrate 27 is on the outer peripheral side.
  • the release substrate 27 is not particularly limited, and PET (Poly Ethylene Terephthalate), OPP (Oriented Polypropylene), PMP (Poly-4-methlpentene-1), PTFE (Polytetrafluoroethylene), and the like can be used.
  • the conductive adhesive film 17 may have a transparent cover film on the binder resin 22. At this time, you may use the tab wire 3 mentioned above as a cover film affixed on the binder resin 22.
  • the tab wire 3 and the conductive adhesive film 17 are laminated and integrated in advance, whereby the peeling base material 27 is peeled off during actual use, and the binder resin 22 of the conductive adhesive film 17 is transferred to the bus bar.
  • the tab wire 3 is connected to the electrodes 11 and 13 by sticking on the tab wire connecting portion 14 of the electrode 11 and the back electrode 13.
  • the conductive adhesive film having a film shape has been described, but there is no problem even if it is in a paste form.
  • the film-like conductive adhesive film 17 containing the solder particles 23 and the paste-like conductive adhesive paste containing the solder particles 23 are defined as “conductive adhesive”.
  • the conductive adhesive film 17 is not limited to a reel shape, but may be a strip shape corresponding to the shape of the tab wire connection portion 14 of the bus bar electrode 11 or the back electrode 13.
  • the conductive adhesive film 17 When the conductive adhesive film 17 is provided as a reel product wound as shown in FIG. 6, the conductive adhesive film 17 preferably has a viscosity of 10 to 10000 kPa ⁇ s, more preferably 10 to 5000 kPa ⁇ s. It is preferable to set it as the range. Thereby, when the conductive adhesive film 17 is wound in a reel shape, blocking due to the so-called protrusion can be prevented, and a predetermined tack force can be maintained. Further, the conductive adhesive film 17 is prevented from being deformed and can maintain a predetermined dimension. Further, when two or more conductive adhesive films 17 are stacked in a strip shape, the conductive adhesive film 17 can similarly prevent deformation and maintain a predetermined dimension.
  • the conductive adhesive film 17 described above dissolves the solder particles 23, the film-forming resin, the liquid epoxy resin, the latent curing agent, and the silane coupling agent in a solvent.
  • a solvent toluene, ethyl acetate or the like, or a mixed solvent thereof can be used.
  • a conductive adhesive film 17 is obtained by applying a resin-generating solution obtained by dissolution onto a release sheet and volatilizing the solvent.
  • the conductive adhesive film 17 is cut into a predetermined length for two of the front electrode and two for the back electrode, and is temporarily attached to a predetermined position on the front and back surfaces of the solar battery cell 2. At this time, the conductive adhesive film 17 is temporarily pasted on the tab line connecting portions 14 of the bus bar electrodes 11 and the back electrode 13 that are formed in plural substantially parallel to the surface of the solar battery cell 2. In the case where a conductive adhesive paste is used as the conductive adhesive, the conductive adhesive paste is applied on the tab line connecting portions 14 of the bus bar electrode 11 and the back electrode 13.
  • the tab wire 3 similarly cut to a predetermined length is placed on the conductive adhesive film 17 in an overlapping manner. Thereafter, the conductive adhesive film 17 is heated and pressed at a predetermined temperature and pressure from above the tab wire 3 by a heating bonder, so that the excess binder resin 22 is placed between the electrodes 11 and 13 and the tab wire 3. The solder particles 23 are sandwiched between the tab wire 3 and the electrodes 11 and 13 and the binder resin 22 is cured in this state.
  • the heat pressurizing condition of the tab wire 3 by the heating bonder is that the binder resin 22 of the conductive adhesive film 17 is thermally cured, the outer layer 25 is metal-bonded to the tab wire 3 and the electrodes 11, 13, and the inner layer 24. Is a condition for preventing melting, and is appropriately set according to the composition of the binder resin 22 and the solder particles 23.
  • the thermal pressing condition of the tab wire 3 by the heating bonder is set to a temperature lower than the melting point of the inner layer 24 and higher than the melting point of the outer layer 25.
  • the conductive adhesive film 17 adheres the tab wire 3 to the electrodes 11 and 13 by the binder resin 22, and the outer layer 25 of the solder particles 23 is metal-bonded to the bus bar electrode 11 and the back electrode 13, thereby forming a hard inner layer. 24 can be connected to each other.
  • solder particles 23 have a flux function by melting the outer layer 25 in contact with the tab wire 3 and the electrodes 11, 13, so the oxidized surface is removed, and the inner layer 24, the tab wire 3 and the electrodes 11, 13 are removed. Connection reliability can be improved.
  • the solar cells 2 are sequentially connected by the tab wires 3 to form the strings 4 and the matrix 5.
  • the plurality of solar cells 2 constituting the matrix 5 are made up of a surface cover 7 having translucency such as glass and translucent plastic, and a back sheet 8 made of glass or PET (Poly Ethylene Terephthalate) film. In between, it seals with the sheet
  • EVA ethylene vinyl acetate resin
  • the solar cell module 1 is formed by attaching a metal frame 9 such as aluminum around the periphery.
  • the solar cell module 1 is provided with the bus bar electrode 11 substantially orthogonal to the finger electrode 12 on the light receiving surface side of the solar cell 2, and the conductive adhesive and the tab wire 3 are provided on the bus bar electrode 11.
  • a so-called bus bar-less structure in which the conductive adhesive and the tab wire 3 are laminated so as to be orthogonal to the finger electrode 12 without providing the bus bar electrode 11 may be employed.
  • the outer layer 25 of the solder particles 23 is metal-bonded with the finger electrode 12, and the inner layer 24 is sandwiched between the tab wire 3 and the finger electrode 12.
  • the solar cell module 1 arrange
  • a conductive adhesive, a tab wire 3 and a light-transmitting sealing material sheet such as EVA that seals the solar battery cell 2 are sequentially laminated on the front and back surfaces of the solar battery cell 2, and this is reduced using a reduced pressure laminator.
  • the tab wire 3 may be heat-pressed on each of the electrodes 11 and 13 by performing a laminating process with glass or PET film.
  • the solar cell module 1 may be formed by coating the tab wire 3 with a flat copper wire or copper foil with the same kind of solder as the outer layer 25 of the solder particles 23. Thereby, the solar cell module 1 more reliably forms a metal bond between the outer layer 25 of the solder particles 23 and the tab wire 3, and further improves the adhesive force and conduction reliability of the tab wire 3 to the electrodes 11 and 13. be able to.
  • FIG. 7 a plurality of types of conductive adhesive film samples 40 having different layer configurations (one or two layers) of solder particles contained in a binder resin and different inner and outer layer compositions were prepared. . And using each sample 40 of these electroconductive adhesive films, two tab wires 41 are hot-pressed on each front surface electrode 31 and back surface electrode 32 of the photoelectric conversion element 30 on which the front surface electrode 31 and the back surface electrode 32 are formed. And glued.
  • the hot pressing conditions were all 180 ° C., 10 sec, and 2 MPa.
  • Sample 40 of conductive adhesive film is Phenoxy resin (YP-50: manufactured by Nippon Steel Chemical Co., Ltd.); 20 parts by mass liquid epoxy resin (EP828: manufactured by Mitsubishi Chemical Corporation); 50 parts by mass solder particles; 10 parts by mass imidazole-based latent curing agent (HX3941HP: Asahi Kasei Corporation); 20 parts by mass toluene; 100 parts by mass was mixed to prepare a resin composition.
  • Phenoxy resin YP-50: manufactured by Nippon Steel Chemical Co., Ltd.
  • 20 parts by mass liquid epoxy resin EP828: manufactured by Mitsubishi Chemical Corporation
  • 50 parts by mass solder particles 10 parts by mass imidazole-based latent curing agent (HX3941HP: Asahi Kasei Corporation)
  • HX3941HP Asahi Kasei Corporation
  • 20 parts by mass toluene 100 parts by mass was mixed to prepare a resin composition.
  • the tab wire 41 is a tab wire that is generally used, and has a width of 2 mm and a thickness of 35 ⁇ m obtained by soldering a long copper foil.
  • the conduction resistance is thermocompression-bonded using a conductive adhesive film on a glass substrate on which an Ag electrode (solid electrode) is formed at the tip 2 mm of two tab wires (Cu foil, 2 mm width, 35 ⁇ m thickness) ( 180 ° C., 2 Mpa, 10 seconds)
  • the resistance between the two tab wires was measured using a digital multimeter.
  • the initial adhesive strength was determined by performing a 90 ° peel test (JIS K6854-1) to peel the tab wire from the conductive adhesive film bonded to each of the front electrode 31 and the back electrode 32 in a 90 ° direction, and peel strength (N / 2 mm).
  • Example 1 used solder particles in which the inner layer was composed of Sn—Ag—Cu solder (melting point: 220 ° C.) and the outer layer was composed of Sn—Bi solder (melting point: 141 ° C.).
  • the average particle diameter of the solder particles is 30 ⁇ m.
  • Example 2 used solder particles in which the inner layer was composed of Sn—Pb solder (melting point: 184 ° C.) and the outer layer was composed of Sn—Bi solder (melting point: 141 ° C.).
  • the average particle diameter of the solder particles is 30 ⁇ m.
  • Example 3 used the same solder particles as in Example 2 except that the average particle diameter of the solder particles was 20 ⁇ m.
  • Example 4 used the same solder particles as in Example 2 except that the average particle diameter of the solder particles was 50 ⁇ m.
  • Comparative Example 1 used solder particles composed of only one layer of Sn—Pb solder (melting point: 184 ° C.). The average particle diameter of the solder particles is 30 ⁇ m.
  • Comparative Example 2 used solder particles composed of only one layer of Sn—Ag—Cu solder (melting point: 220 ° C.). The average particle diameter of the solder particles is 30 ⁇ m.
  • Comparative Example 3 used solder particles composed of only one layer of Sn—Bi solder (melting point: 141 ° C.). The average particle diameter of the solder particles is 30 ⁇ m.
  • Comparative Example 4 used solder particles in which the inner layer was composed of Sn—Pb solder (melting point: 184 ° C.) and the outer layer was composed of Sn—Ag—Cu solder (melting point: 220 ° C.).
  • the average particle diameter of the solder particles is 30 ⁇ m.
  • Comparative Example 5 instead of the solder particles, a plated resin in which the inner layer is made of resin and the outer layer is coated with Ni—Au plating was used.
  • the initial conduction resistance (m ⁇ ) and the conduction resistance (m ⁇ ) after a high temperature and high humidity test (85 ° C., 85% RH ⁇ 3000 hr) were measured.
  • the initial adhesive force (N / 2 mm) between the tab wire 3 and the electrodes 31 and 32 was measured.
  • the initial adhesive strength was measured by peeling the 90 ° peel strength under conditions of a pulling speed of 30 mm / min.
  • the initial adhesive strength is as high as 5 N / 2 mm or more. On the other hand, in Comparative Examples 1 to 4, the initial adhesive strength was as low as 5 N / 2 mm or less.
  • Comparative Example 1 and Comparative Example 2 that do not have a multilayer structure, no metal bond is formed between the solder particles and the tab wires and the electrodes 31 and 32.
  • Comparative Example 3 the solder particles are melted and the tab wires are melted. Between the electrode 31 and the electrode 31 and 32, connection failure was observed in the high-temperature and high-humidity test.
  • Comparative Example 4 having a multilayer structure, since the outer layer is made of higher melting point solder than the inner layer, the outer layer and the tab wires and the electrodes 31 and 32 do not form a metal bond and are connected in a high-temperature and high-humidity test. Defects were seen.
  • Comparative Example 5 in which a plated resin was used instead of the solder particles, the adhesive strength was weak, and an increase in conduction resistance was observed in the high temperature and high humidity test.

Abstract

The present invention prevents the separation of conductive particles from a tab wire and an electrode regardless of binder performance. The present invention is provided with: a plurality of solar cells (2); and tab wires (3) that are adhered via a thermoset conductive adhesive (17) including conductive particles onto electrodes (11, 13) that are respectively formed on the front surfaces of the solar cells (2) and the back surfaces of adjacent solar cells (2) to connect pairs of solar cells (2). The conductive adhesive (17) includes solder particles (23). The solder particles (23) have a multi-layer structure constituted from at least an inner layer (24) and an outer layer (25), wherein the melting point of the solder forming the inner layer (24) is higher than the melting point of the solder forming the outer layer (25).

Description

太陽電池モジュール、太陽電池モジュールの製造方法、導電性接着剤Solar cell module, method for manufacturing solar cell module, conductive adhesive
　本発明は、タブ線によって複数の太陽電池セルが接続された太陽電池モジュールに関し、特に導電性粒子を含有する導電性接着剤を介して太陽電池セルの電極とタブ線とを接続する太陽電池モジュール、太陽電池モジュールの製造方法及び導電性接着剤に関するものである。
　本出願は、日本国において２０１１年３月２４日に出願された日本特許出願番号特願２０１１－６６５４３を基礎として優先権を主張するものであり、この出願は参照されることにより、本出願に援用される。 The present invention relates to a solar battery module in which a plurality of solar battery cells are connected by a tab wire, and in particular, a solar battery module for connecting an electrode of a solar battery cell and a tab wire via a conductive adhesive containing conductive particles. The present invention relates to a method for manufacturing a solar cell module and a conductive adhesive.
This application claims priority on the basis of Japanese Patent Application No. 2011-66543 filed on March 24, 2011 in Japan, and this application is incorporated herein by reference. Incorporated.
　例えば結晶シリコン系太陽電池モジュールでは、複数の隣接する太陽電池セルが、インターコネクタとなるタブ線により接続されている。タブ線は、その一端側を一の太陽電池セルの表面電極に接続され、他端側を隣接する太陽電池セルの裏面電極に接続することにより、各太陽電池セルを直列に接続する。このとき、タブ線は、一端側の一面側が一の太陽電池セルの表面電極に接着され、他端側の他面側が隣接する太陽電池セルの裏面電極に接着されている。 For example, in a crystalline silicon solar cell module, a plurality of adjacent solar cells are connected by a tab wire serving as an interconnector. One end side of the tab wire is connected to the front surface electrode of one solar battery cell, and the other end side is connected to the back surface electrode of the adjacent solar battery cell, thereby connecting the solar battery cells in series. At this time, one surface of the tab wire is bonded to the surface electrode of one solar cell, and the other surface of the other end is bonded to the back electrode of the adjacent solar cell.
　具体的に、太陽電池セルは、銀ペーストをスクリーン印刷すること等により、受光面にバスバー電極が形成され、裏面接続部にＡｇ電極が形成されている。なお、太陽電池セル裏面の接続部以外の領域はＡｌ電極やＡｇ電極が形成されている。 Specifically, in the solar battery cell, a bus bar electrode is formed on the light receiving surface and an Ag electrode is formed on the back surface connection portion by screen printing of silver paste. In addition, Al electrodes and Ag electrodes are formed in regions other than the connection portion on the back surface of the solar battery cell.
　また、タブ線は、リボン状銅箔の両面にハンダコート層が設けられること等により形成される。具体的に、タブ線は、厚さ０．０５～０．２ｍｍ程度に圧延した銅箔をスリットし、あるいは銅ワイヤーを平板状に圧延するなどして得た幅１～３ｍｍの平角銅線に、ハンダメッキやディップハンダ付け等を施すことにより形成される。 Further, the tab wire is formed by providing a solder coat layer on both sides of the ribbon-like copper foil. Specifically, the tab wire is a rectangular copper wire having a width of 1 to 3 mm obtained by slitting a copper foil rolled to a thickness of about 0.05 to 0.2 mm or rolling a copper wire into a flat plate shape. It is formed by performing solder plating, dip soldering, or the like.
　太陽電池セルとタブ線との接続は、タブ線を太陽電池セルの各電極上に配置し、加熱ボンダーによって熱加圧することにより、タブ線表面に形成したハンダを溶融、冷却することにより行う（特許文献１）。 The connection between the solar battery cell and the tab wire is performed by disposing the tab wire on each electrode of the solar battery cell and applying heat and pressure with a heating bonder to melt and cool the solder formed on the tab wire surface ( Patent Document 1).
　しかし、半田付けでは約２６０℃と高温による接続処理が行われるため、太陽電池セルの反りや割れ、タブ線と表面電極及び裏面電極との接続部に生じる内部応力等により、太陽電池セルの表面電極及び裏面電極とタブ線との間の接続信頼性が低下することが懸念される。 However, since soldering is performed at a high temperature of about 260 ° C., the surface of the solar cell is warped or cracked, the internal stress generated at the connection between the tab wire, the front electrode and the back electrode, etc. There is a concern that the connection reliability between the electrode and the back electrode and the tab wire is lowered.
　そこで、従来、太陽電池セルの表面電極及び裏面電極とタブ線との接続に、比較的低い温度での熱圧着処理による接続が可能な導電性接着フィルムが使用されている（特許文献２）。このような導電性接着フィルムとしては、平均粒径が数μｍオーダーの球状または鱗片状の導電性粒子を熱硬化型バインダー樹脂組成物に分散してフィルム化したものが使用されている。導電性粒子は、例えば、ニッケル、金、銀、銅などの金属粒子や、樹脂粒子をコア材とし最外層に金めっきなどを施したものが一般に用いられている。 Therefore, conventionally, a conductive adhesive film that can be connected by thermocompression treatment at a relatively low temperature is used to connect the front and back electrodes of the solar battery cell and the tab wire (Patent Document 2). As such a conductive adhesive film, a film obtained by dispersing spherical or scaly conductive particles having an average particle size on the order of several μm in a thermosetting binder resin composition is used. As the conductive particles, for example, metal particles such as nickel, gold, silver, and copper, or particles having resin particles as a core material and gold plating or the like are generally used.
　図８に示すように、導電性接着フィルム５０は、表面電極及び裏面電極とタブ線５１との間に介在された後、タブ線５１の上から加熱ボンダーによって熱加圧される。これにより、図９に示すように、導電性接着フィルム５０は、バインダー樹脂が流動性を示して電極、タブ線５１間より流出されるとともに、導電性粒子５４が電極５３とタブ線５１間に挟持されてこの間の導通を図り、この状態でバインダー樹脂が熱硬化する。このように、タブ線５１によって複数の太陽電池セル５２が直列接続されたストリングスが形成される。 As shown in FIG. 8, the conductive adhesive film 50 is interposed between the front and back electrodes and the tab wire 51, and is then hot-pressed from above the tab wire 51 by a heating bonder. As a result, as shown in FIG. 9, the conductive adhesive film 50 allows the binder resin to flow out between the electrode and the tab wire 51, while the conductive resin 54 flows between the electrode 53 and the tab wire 51. In this state, the binder resin is thermoset by being sandwiched and conducting between them. In this way, a string in which a plurality of solar cells 52 are connected in series by the tab wire 51 is formed.
　導電性接着フィルム５０を用いてタブ線５１と表面電極及び裏面電極とが接続された複数の太陽電池セル５２は、ガラス、透光性プラスチックなどの透光性を有する表面保護材と、ＰＥＴ（Poly Ethylene Terephthalate）等のフィルムからなる背面保護材との間に、エチレンビニルアセテート樹脂（ＥＶＡ）等の透光性を有する封止材により封止される。 The plurality of solar cells 52 in which the tab wire 51 and the front and back electrodes are connected using the conductive adhesive film 50 are made of a surface protecting material having translucency such as glass and translucent plastic, PET ( It is sealed with a light-transmitting sealing material such as ethylene vinyl acetate resin (EVA) between a back protective material made of a film such as Poly Ethylene Terephthalate).
特開２００４－３５６３４９号公報JP 2004-356349 A 特開２００８－１３５６５４号公報JP 2008-135654 A
　この種の太陽電池モジュールでは、導電性粒子５４がタブ線５１及び太陽電池セルの表裏面の各電極５３に接触することにより導通を図るものであるため、導電性接着フィルム５０のバインダー樹脂の性能によって電気的な接続信頼性が左右される。 In this type of solar battery module, the conductive particles 54 are intended to conduct by contacting the tab wires 51 and the respective electrodes 53 on the front and back surfaces of the solar battery cell, so that the performance of the binder resin of the conductive adhesive film 50 is improved. Depends on the electrical connection reliability.
　すなわち、太陽電池モジュールは、実使用に供されると、高温多湿の環境に長期に亘って繰り返し曝されるおそれがあり、これにより、導電性接着フィルム５０のバインダー樹脂が劣化、変質し、導電性粒子５４とタブ線５１及び電極５３との接触が維持されず、発電効率が低下するおそれがある。 That is, when the solar cell module is put into actual use, it may be repeatedly exposed to a high-temperature and high-humidity environment over a long period of time. As a result, the binder resin of the conductive adhesive film 50 is deteriorated and deteriorated. Contact between the conductive particles 54 and the tab wires 51 and the electrodes 53 is not maintained, and power generation efficiency may be reduced.
　そこで、本願は、バインダー樹脂の性能にかかわらず、高温多湿の環境に曝された場合でも、導電性粒子とタブ線及び電極との接触部位の離間を防止でき、発電効率を維持することができる太陽電池モジュール、太陽電池モジュールの製造方法、及び導電性接着剤を提供することを目的とする。 Therefore, the present application can prevent separation of contact portions between the conductive particles, the tab wires, and the electrodes even when exposed to a high-temperature and high-humidity environment, regardless of the performance of the binder resin, and can maintain power generation efficiency. It aims at providing a solar cell module, a manufacturing method of a solar cell module, and a conductive adhesive.
　上述した課題を解決するために、本発明に係る太陽電池モジュールは、複数の太陽電池セルと、上記太陽電池セルの表面及び隣接する太陽電池セルの裏面にそれぞれ形成された電極上に導電性粒子を含有する熱硬化性の導電性接着剤を介して接着され、複数の上記太陽電池セル同士を接続するタブ線とを備え、上記導電性接着剤にはハンダ粒子が含有され、上記ハンダ粒子は、少なくとも内層及び外層からなる多層構造であり、上記内層を構成するハンダの融点が、上記外層を構成するハンダの融点よりも高いものである。 In order to solve the above-described problems, a solar cell module according to the present invention includes a plurality of solar cells and conductive particles on electrodes formed on the surface of the solar cell and the back surface of the adjacent solar cell, respectively. And a tab wire for connecting a plurality of the solar cells, the conductive adhesive contains solder particles, and the solder particles are bonded to each other through a thermosetting conductive adhesive containing The multilayer structure is composed of at least an inner layer and an outer layer, and the melting point of the solder constituting the inner layer is higher than the melting point of the solder constituting the outer layer.
　また、本発明に係る太陽電池モジュールの製造方法は、太陽電池セルの表面電極に導電性粒子を含有する熱硬化性の導電性接着剤を介してタブ線の一端側を配置し、上記太陽電池セルと隣接する太陽電池セルの裏面電極に導電性粒子を含有する熱硬化性の導電性接着剤を介して上記タブ線の他端側を配置する工程と、上記タブ線を上記表面電極及び上記裏面電極へ熱加圧し、上記導電性接着剤によって上記タブ線を上記表面電極及び上記裏面電極へ接着する工程とを有し、上記導電性接着剤にはハンダ粒子が含有され、上記ハンダ粒子は、少なくとも内層及び外層からなる多層構造であり、上記内層を構成するハンダの融点が、上記外層を構成するハンダの融点よりも高いものである。 Moreover, the manufacturing method of the solar cell module which concerns on this invention arrange | positions the one end side of a tab wire through the thermosetting conductive adhesive which contains electroconductive particle in the surface electrode of a photovoltaic cell, The said solar cell A step of disposing the other end side of the tab wire via a thermosetting conductive adhesive containing conductive particles on the back electrode of the solar cell adjacent to the cell; Heat-pressing the back electrode and bonding the tab wire to the front electrode and the back electrode with the conductive adhesive, the conductive adhesive contains solder particles, and the solder particles The multilayer structure is composed of at least an inner layer and an outer layer, and the melting point of the solder constituting the inner layer is higher than the melting point of the solder constituting the outer layer.
　また、本発明に係る導電性接着剤は、太陽電池セルに形成された電極と、複数の上記太陽電池セル同士を接続するタブ線との間に介在され、熱加圧されることにより上記電極と上記タブ線とを接着させる導電性接着剤において、熱硬化性のバインダー樹脂と、上記バインダー樹脂中に含有されたハンダ粒子とを備え、上記ハンダ粒子は、少なくとも内層及び外層からなる多層構造であり、上記内層を構成するハンダの融点が、上記外層を構成するハンダの融点よりも高いものである。 In addition, the conductive adhesive according to the present invention is interposed between the electrode formed in the solar battery cell and the tab wire connecting the plurality of solar battery cells, and is heated and pressed to thereby form the electrode. In the conductive adhesive for bonding the tab wire to each other, a thermosetting binder resin and solder particles contained in the binder resin, the solder particles having a multilayer structure composed of at least an inner layer and an outer layer. And the melting point of the solder constituting the inner layer is higher than the melting point of the solder constituting the outer layer.
　本発明によれば、ハンダ粒子は、少なくとも内層及び外層からなる多層構造であり、内層を構成するハンダの融点が外層を構成するハンダの融点よりも高い。かかるハンダ粒子を含有する導電性接着剤を用いることにより、外層がタブ線や太陽電池セルの電極と金属結合するとともに硬い内層がタブ線と電極に挟持される。したがって、導電性接着剤のバインダー樹脂が劣化した場合にもハンダ粒子とタブ線及び電極との電気的な接続を維持することができる。 According to the present invention, the solder particles have a multilayer structure composed of at least an inner layer and an outer layer, and the melting point of the solder constituting the inner layer is higher than the melting point of the solder constituting the outer layer. By using a conductive adhesive containing such solder particles, the outer layer is metal-bonded to the tab wire or the electrode of the solar battery cell, and the hard inner layer is sandwiched between the tab wire and the electrode. Therefore, even when the binder resin of the conductive adhesive is deteriorated, the electrical connection between the solder particles, the tab wire, and the electrode can be maintained.
図１は、太陽電池モジュールを示す分解斜視図である。FIG. 1 is an exploded perspective view showing a solar cell module. 図２は、太陽電池セルのストリングスを示す断面図である。FIG. 2 is a cross-sectional view showing strings of solar cells. 図３は、太陽電池セルの裏面電極及び接続部を示す平面図である。FIG. 3 is a plan view showing a back electrode and a connection part of the solar battery cell. 図４は、導電性接着フィルムを示す断面図である。FIG. 4 is a cross-sectional view showing a conductive adhesive film. 図５は、ハンダ粒子を介して接続されたタブ線及び電極を示す断面図である。FIG. 5 is a cross-sectional view showing tab wires and electrodes connected via solder particles. 図６は、リール状に巻回された導電性接着フィルムを示す図である。FIG. 6 is a diagram showing a conductive adhesive film wound in a reel shape. 図７は、実施例を説明するための図である。FIG. 7 is a diagram for explaining the embodiment. 図８は、従来の太陽電池モジュールを示す斜視図である。FIG. 8 is a perspective view showing a conventional solar cell module. 図９は、導電性粒子を介してタブ線と電極とが接続されている状態を示す断面図である。FIG. 9 is a cross-sectional view showing a state where the tab wire and the electrode are connected via the conductive particles.
　以下、本発明が適用された太陽電池モジュール、太陽電池モジュールの製造方法について、図面を参照しながら詳細に説明する。なお、本発明は、以下の実施形態のみに限定されるものではなく、本発明の趣旨を逸脱しない範囲内において種々の変更が可能であることは勿論である。 Hereinafter, a solar cell module to which the present invention is applied and a method for manufacturing the solar cell module will be described in detail with reference to the drawings. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made without departing from the spirit of the present invention.
　［太陽電池モジュール］
　本発明が適用された太陽電池モジュール１は、図１～図３に示すように、複数の太陽電池セル２がインターコネクタとなるタブ線３によって直列に接続されたストリングス４を有し、このストリングス４を複数配列したマトリクス５を備える。そして、太陽電池モジュール１は、このマトリクス５が封止接着剤のシート６で挟まれ、受光面側に設けられた表面カバー７及び裏面側に設けられたバックシート８とともに一括してラミネートされ、最後に、周囲にアルミニウムなどの金属フレーム９が取り付けられることにより形成される。 [Solar cell module]
As shown in FIGS. 1 to 3, a solar cell module 1 to which the present invention is applied has a string 4 in which a plurality of solar cells 2 are connected in series by a tab wire 3 serving as an interconnector. A matrix 5 in which a plurality of 4 are arranged is provided. And the solar cell module 1 is laminated together with the front cover 7 provided on the light receiving surface side and the back sheet 8 provided on the back surface side, with the matrix 5 sandwiched between the sealing adhesive sheets 6. Finally, a metal frame 9 such as aluminum is attached to the periphery.
　封止接着剤としては、例えばエチレンビニルアセテート樹脂（ＥＶＡ）等の透光性封止材が用いられる。また、表面カバー７としては、例えば、ガラスや透光性プラスチック等の透光性の材料が用いられる。また、バックシート８としては、ガラスや、アルミニウム箔を樹脂フィルムで挟持した積層体等が用いられる。 As the sealing adhesive, for example, a translucent sealing material such as ethylene vinyl acetate 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.
　太陽電池モジュールの各太陽電池セル２は、光電変換素子１０を有する。光電変換素子１０は、単結晶型シリコン光電変換素子、多結晶型光電変換素子を用いる結晶シリコン系太陽電池や、アモルファスシリコンからなる薄膜シリコン系太陽電池、アモルファスシリコンからなるセルと微結晶シリコンやアモルファスシリコンゲルマニウムからなるセルとを積層させた多接合型の薄膜シリコン系太陽電池、いわゆる化合物薄膜系太陽電池、有機系、量子ドット型など、各種光電変換素子１０を用いることができる。 Each solar battery cell 2 of the solar battery module has a photoelectric conversion element 10. The photoelectric conversion element 10 includes a single crystal silicon photoelectric conversion element, a crystalline silicon solar cell using a polycrystalline photoelectric conversion element, a thin film silicon solar cell made of amorphous silicon, a cell made of amorphous silicon, a microcrystalline silicon or an amorphous Various photoelectric conversion elements 10 such as a multi-junction thin film silicon solar cell in which cells made of silicon germanium are stacked, a so-called compound thin film solar cell, an organic system, and a quantum dot type can be used.
　また、光電変換素子１０は、受光面側に内部で発生した電気を集電するフィンガー電極１２とフィンガー電極１２の電気を集電するバスバー電極１１とが設けられている。バスバー電極１１及びフィンガー電極１２は、太陽電池セル２の受光面となる表面に、例えばＡｇペーストがスクリーン印刷等により塗布された後、焼成されることにより形成される。また、フィンガー電極１２は、受光面の全面に亘って、例えば約５０～２００μｍ程度の幅を有するラインが、所定間隔、例えば２ｍｍおきに、ほぼ平行に複数形成されている。バスバー電極１１は、フィンガー電極１２と略直交するように形成され、また、太陽電池セル２の面積に応じて複数形成されている。 Further, the photoelectric conversion element 10 is provided with a finger electrode 12 for collecting electricity generated inside and a bus bar electrode 11 for collecting electricity of the finger electrode 12 on the light receiving surface side. The bus bar electrode 11 and the finger electrode 12 are formed, for example, by applying an Ag paste on the surface to be a light receiving surface of the solar battery cell 2 by screen printing or the like and then baking it. Further, the finger electrode 12 has a plurality of lines having a width of about 50 to 200 μm, for example, approximately parallel to each other at a predetermined interval, for example, every 2 mm, over the entire light receiving surface. The bus bar electrodes 11 are formed so as to be substantially orthogonal to the finger electrodes 12, and a plurality of bus bar electrodes 11 are formed according to the area of the solar battery cell 2.
　また、光電変換素子１０は、受光面と反対の裏面側に、アルミニウムや銀からなる裏面電極１３が設けられている。裏面電極１３は、図２及び図３に示すように、例えばアルミニウムや銀からなる電極が、スクリーン印刷やスパッタ等により太陽電池セル２の裏面に形成される。裏面電極１３は、後述する導電性接着フィルム１７を介してタブ線３が接続されるタブ線接続部１４を有する。 The photoelectric conversion element 10 is provided with a back electrode 13 made of aluminum or silver on the back side opposite to the light receiving surface. As shown in FIGS. 2 and 3, the back electrode 13 is formed of an electrode made of, for example, aluminum or silver on the back surface of the solar battery cell 2 by screen printing, sputtering, or the like. The back electrode 13 has a tab wire connecting portion 14 to which the tab wire 3 is connected via a conductive adhesive film 17 described later.
　そして、太陽電池セル２は、タブ線３によって、表面に形成された各バスバー電極１１と、隣接する太陽電池セル２の裏面電極１３とが電気的に接続され、これにより直列に接続されたストリングス４を構成する。タブ線３とバスバー電極１１及び裏面電極１３とは、後述する導電性接着フィルム１７によって接続される。 The solar battery cell 2 is electrically connected to each bus bar electrode 11 formed on the surface by the tab wire 3 and the back electrode 13 of the adjacent solar battery cell 2, thereby connecting the strings connected in series. 4 is configured. The tab wire 3 is connected to the bus bar electrode 11 and the back electrode 13 by a conductive adhesive film 17 described later.
　［タブ線］
　タブ線３は、図２に示すように、隣接する太陽電池セル２Ｘ、２Ｙ、２Ｚの各間を電気的に接続する長尺状の導電性基材である。タブ線３は、例えば厚さ５０～３００μｍに圧延された銅箔やアルミ箔をスリットし、あるいは銅やアルミなどの細い金属ワイヤーを平板状に圧延することにより、導電性接着フィルム１７とほぼ同じ幅の１～３ｍｍ幅の平角の銅線を得る。そして、タブ線３は、この平角銅線に、金メッキ、銀メッキ、スズメッキ、ハンダメッキ等を施すことにより形成される。 [Tab line]
As shown in FIG. 2, the tab line 3 is a long conductive substrate that electrically connects each of the adjacent solar cells 2X, 2Y, and 2Z. The tab wire 3 is substantially the same as the conductive adhesive film 17 by, for example, slitting a copper foil or aluminum foil rolled to a thickness of 50 to 300 μm, or rolling a thin metal wire such as copper or aluminum into a flat plate shape. A flat copper wire having a width of 1 to 3 mm is obtained. The tab wire 3 is formed by applying gold plating, silver plating, tin plating, solder plating, or the like to the flat copper wire.
　［導電性接着フィルム］
　本発明が適用された導電性接着フィルム１７は、図４に示すように、バインダー樹脂２２に導電性粒子が高密度に含有された熱硬化性のバインダー樹脂層である。導電性粒子には、以下に詳述するハンダ粒子２３が含有されている。また、導電性接着フィルム１７は、押し込み性の観点から、バインダー樹脂２２の最低溶融粘度が、１００～１０００００Ｐａ・ｓであることが好ましい。導電性接着フィルム１７は、最低溶融粘度が低すぎると低圧着から本硬化の過程で樹脂が流動してしまい接続不良やセル受光面へのはみ出しが生じやすく、受光率低下の原因ともなる。また、最低溶融粘度が高すぎてもフィルム貼着時に不良を発生しやすく、接続信頼性に悪影響が出る場合もある。なお、最低溶融粘度については、サンプルを所定量回転式粘度計に装填し、所定の昇温速度で上昇させながら測定することができる。 [Conductive adhesive film]
As shown in FIG. 4, the conductive adhesive film 17 to which the present invention is applied is a thermosetting binder resin layer in which conductive particles are contained in the binder resin 22 at a high density. The conductive particles contain solder particles 23 described in detail below. The conductive adhesive film 17 preferably has a minimum melt viscosity of 100 to 100,000 Pa · s from the viewpoint of indentability. If the minimum melt viscosity of the conductive adhesive film 17 is too low, the resin flows in the process of low pressure bonding to main curing, and connection failure or protrusion to the cell light receiving surface is likely to occur, which causes a decrease in the light receiving rate. Moreover, even if the minimum melt viscosity is too high, defects are likely to occur when the film is adhered, and the connection reliability may be adversely affected. The minimum melt viscosity can be measured while a sample is loaded in a predetermined amount of rotational viscometer and raised at a predetermined temperature increase rate.
　［ハンダ粒子］
　本発明に係るハンダ粒子２３は、互いに融点の異なるハンダが多層化されている。ハンダ粒子２３は、例えば図５に示すように、コアとなる内層２４と、内層２４の周囲に設けられた外層２５との２層からなる。 [Solder particles]
The solder particles 23 according to the present invention have multiple layers of solders having different melting points. For example, as shown in FIG. 5, the solder particles 23 are composed of two layers of an inner layer 24 serving as a core and an outer layer 25 provided around the inner layer 24.
　図５に示すハンダ粒子２３の内層２４は、タブ線３と電極１１，１３とに挟持されることによりタブ線３と電極１１，１３との導通を図るものである。また、図５に示すハンダ粒子２３の外層２５は、タブ線３と電極１１，１３と金属結合することにより、タブ線３と電極１１，１３との電気的な接続信頼性を確保するものである。 The inner layer 24 of the solder particles 23 shown in FIG. 5 is intended to establish conduction between the tab wire 3 and the electrodes 11 and 13 by being sandwiched between the tab wire 3 and the electrodes 11 and 13. Further, the outer layer 25 of the solder particles 23 shown in FIG. 5 ensures electrical connection reliability between the tab wire 3 and the electrodes 11 and 13 by metal bonding with the tab wire 3 and the electrodes 11 and 13. is there.
　ハンダ粒子２３は、内層２４を構成するハンダの融点が、外層２５を構成するハンダの融点よりも高い。したがって、ハンダ粒子２３は、タブ線３が導電性接着フィルム１７を介して電極１１，１３上に熱加圧されることにより、外層２５がタブ線３と電極１１，１３に金属結合し、内層２４がタブ線３と電極１１，１３とに挟持されてこの間の導通を図る。 In the solder particles 23, the melting point of the solder constituting the inner layer 24 is higher than the melting point of the solder constituting the outer layer 25. Therefore, the solder particles 23 are thermally bonded to the tab wires 3 and the electrodes 11 and 13 by thermally pressing the tab wires 3 onto the electrodes 11 and 13 via the conductive adhesive film 17, so that the inner layers 24 is sandwiched between the tab wire 3 and the electrodes 11 and 13 to achieve electrical connection therebetween.
　すなわち、太陽電池モジュール１は、外層２５がタブ線３と電極１１，１３とに金属結合するとともに硬い内層２４がタブ線３と電極１１，１３に挟持されることにより導通を図るものであり、ハンダ粒子２３が単にタブ線３と電極１１，１３とに接触することにより導通を図るものではない。このようなハンダ粒子２３を含有する導電性接着フィルム１７を用いることにより、導電性接着フィルム１７のバインダー樹脂２２が劣化した場合にもハンダ粒子２３とタブ線３及び電極１１，１３との電気的な接続を維持することができる。 That is, in the solar cell module 1, the outer layer 25 is metal-bonded to the tab wire 3 and the electrodes 11 and 13, and the hard inner layer 24 is sandwiched between the tab wire 3 and the electrodes 11 and 13, thereby achieving conduction. The solder particles 23 simply do not contact the tab wire 3 and the electrodes 11 and 13 to achieve conduction. By using the conductive adhesive film 17 containing such solder particles 23, even when the binder resin 22 of the conductive adhesive film 17 deteriorates, the electrical connection between the solder particles 23, the tab wire 3, and the electrodes 11, 13 is achieved. Connection can be maintained.
　なお、ハンダ粒子２３は、タブ線３及び電極１１，１３と金属結合する外層２５と、タブ線３及び電極１１，１３に挟持される内層２４とを備えるものであれば２層構造に限らず、３層以上に多層化したものであってもよい。ハンダ粒子２３は、３層以上に形成した場合も、最外層にタブ線３や電極１１，１３と金属結合する外層２５が設けられ、その内側にタブ線３及び電極１１，１３に挟持される内層２４が設けられる。 The solder particles 23 are not limited to a two-layer structure as long as they have an outer layer 25 that is metal-bonded to the tab wire 3 and the electrodes 11 and 13 and an inner layer 24 that is sandwiched between the tab wire 3 and the electrodes 11 and 13. Three or more layers may be used. Even when the solder particles 23 are formed in three or more layers, the outer layer 25 that is metal-bonded to the tab wire 3 and the electrodes 11 and 13 is provided in the outermost layer, and is sandwiched between the tab wire 3 and the electrodes 11 and 13 inside thereof. An inner layer 24 is provided.
　また、ハンダ粒子２３は、内層２４を構成するハンダの融点が、導電性接着フィルム１７のバインダー樹脂２２の硬化温度よりも高いことが好ましい。これにより、ハンダ粒子２３は、タブ線３が導電性接着フィルム１７を介して電極１１，１３上に熱加圧される際にバインダー樹脂２２の硬化温度に熱せられても、内層２４が溶融することなく、硬さが維持され確実にタブ線３及び電極１１，１３の間に挟持されることができる。また、内層２４が硬いことから外層２５やタブ線３及び電極１１，１３に加熱ボンダーによる圧力がかかり、金属結合を促進させる。 The solder particles 23 preferably have a melting point of the solder constituting the inner layer 24 higher than the curing temperature of the binder resin 22 of the conductive adhesive film 17. Thereby, even if the solder particles 23 are heated to the curing temperature of the binder resin 22 when the tab wire 3 is hot-pressed on the electrodes 11 and 13 via the conductive adhesive film 17, the inner layer 24 is melted. Therefore, the hardness can be maintained and the tab wire 3 and the electrodes 11 and 13 can be securely held. Further, since the inner layer 24 is hard, pressure is applied to the outer layer 25, the tab wire 3 and the electrodes 11 and 13 by a heating bonder to promote metal bonding.
　また、ハンダ粒子２３は、外層２５を構成するハンダの融点が、導電性接着フィルム１７のバインダー樹脂２２の硬化温度以下であることが好ましい。これにより、ハンダ粒子２３は、タブ線３が導電性接着フィルム１７を介して電極１１，１３上に熱加圧される際にバインダー樹脂２２の硬化温度に熱せられることにより、外層２５が溶融し、確実にタブ線３及び電極１１，１３と金属結合させることができる。 The solder particles 23 preferably have a melting point of the solder constituting the outer layer 25 equal to or lower than the curing temperature of the binder resin 22 of the conductive adhesive film 17. As a result, the solder particles 23 are heated to the curing temperature of the binder resin 22 when the tab wire 3 is hot-pressed on the electrodes 11 and 13 via the conductive adhesive film 17, so that the outer layer 25 is melted. The tab wire 3 and the electrodes 11 and 13 can be surely metal-bonded.
　ハンダ粒子２３は、粒子の核となる内層２４を作り、この内層２４の周囲にコーティング層となる外層２５を形成することによって製造することができる。内層２４の作製は、通常のはんだ粉末の製造に用いられる場合と同様の方法である、アトマイズ法などを使用することができる。内層２４の周囲をコーティングする外層２５の形成には、蒸着法、スパッタリング法、無電解めっき法、あるいはゾルゲル法などを利用することができる。外層２５は、内層２４の全体を覆うように形成するため、例えば蒸着法やスパッタリング法を用いるような場合には、内層２４を揺動させることなどを併せて行うのが好ましい。 The solder particles 23 can be manufactured by forming an inner layer 24 that becomes the core of the particles and forming an outer layer 25 that becomes a coating layer around the inner layer 24. For the production of the inner layer 24, an atomizing method or the like, which is the same method as used in the production of a normal solder powder, can be used. For forming the outer layer 25 that coats the periphery of the inner layer 24, a vapor deposition method, a sputtering method, an electroless plating method, a sol-gel method, or the like can be used. Since the outer layer 25 is formed so as to cover the entire inner layer 24, for example, when an evaporation method or a sputtering method is used, it is preferable that the inner layer 24 is also swung.
　このようなハンダ粒子２３は、例えば、内層を構成するハンダとして、Ｓｎ－Ａｇ－Ｃｕ系ハンダ（融点：２２０℃）又はＳｎ－Ｐｂ系ハンダ（融点：１８４℃）を用い、外層を構成するハンダとしてＳｎ－Ｂｉ系ハンダ（融点：１４１℃）を用いることができる。これにより、タブ線３がバスバー電極１１や裏面電極１３へ１８０℃で熱加圧されることにより、外層２５が溶融してタブ線３や電極１１，１３と金属結合するとともに、内層２４がタブ線３及び電極１１，１３に挟持される。 Such solder particles 23 use, for example, Sn—Ag—Cu solder (melting point: 220 ° C.) or Sn—Pb solder (melting point: 184 ° C.) as the solder constituting the inner layer, and the solder constituting the outer layer. Sn—Bi solder (melting point: 141 ° C.) can be used. As a result, the tab wire 3 is thermally pressed to the bus bar electrode 11 and the back electrode 13 at 180 ° C., so that the outer layer 25 melts and is metal-bonded to the tab wire 3 and the electrodes 11 and 13 and the inner layer 24 is tabbed. It is sandwiched between the wire 3 and the electrodes 11 and 13.
　また、ハンダ粒子２３は、内層を構成するハンダの融点が、タブ線３の熱加圧温度よりも高いことが好ましく、外層を構成するハンダの融点が、タブ線３の熱加圧温度以下であることが好ましい。 The solder particles 23 preferably have a melting point of solder constituting the inner layer higher than the thermal pressurization temperature of the tab wire 3, and a melting point of solder constituting the outer layer is equal to or lower than the thermal pressurization temperature of the tab wire 3. Preferably there is.
　また、ハンダ粒子２３の粒子径としては、１～１００μｍの範囲で使用することができ、２０～５０μｍの範囲を好適に使用することができる。 The particle size of the solder particles 23 can be used in the range of 1 to 100 μm, and the range of 20 to 50 μm can be preferably used.
　したがって、太陽電池モジュール１は、各太陽電池セル２におけるタブ線３の電極１１，１３への接続強度及び電気的な接続信頼性を向上することができ、かつ実使用下における高温多湿の環境下に繰り返し曝された場合にも、ハンダ粒子２３を介したタブ線３及び電極１１，１３の接続信頼性を維持することができる。 Therefore, the solar cell module 1 can improve the connection strength and electrical connection reliability of the tab wire 3 to the electrodes 11 and 13 in each solar cell 2 and is in a high temperature and high humidity environment under actual use. The connection reliability of the tab wire 3 and the electrodes 11 and 13 through the solder particles 23 can be maintained even when repeatedly exposed to.
　［バインダー樹脂］
　導電性接着フィルム１７のバインダー樹脂２２の組成は、上述のような特徴を害さない限り、特に制限されないが、より好ましくは、膜形成樹脂と、液状エポキシ樹脂と、潜在性硬化剤と、シランカップリング剤とを含有する。 [Binder resin]
The composition of the binder resin 22 of the conductive adhesive film 17 is not particularly limited as long as it does not impair the above-described characteristics, but more preferably a film-forming resin, a liquid epoxy resin, a latent curing agent, a silane cup Contains a ring agent.
　膜形成樹脂は、平均分子量が１００００以上の高分子量樹脂に相当し、フィルム形成性の観点から、１００００～８００００程度の平均分子量であることが好ましい。膜形成樹脂としては、エポキシ樹脂、変性エポキシ樹脂、ウレタン樹脂、フェノキシ樹脂等の種々の樹脂を使用することができ、その中でも膜形成状態、接続信頼性等の観点からフェノキシ樹脂が好適に用いられる。 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. .
　液状エポキシ樹脂としては、常温で流動性を有していれば、特に制限はなく、市販のエポキシ樹脂が全て使用可能である。このようなエポキシ樹脂としては、具体的には、ナフタレン型エポキシ樹脂、ビフェニル型エポキシ樹脂、フェノールノボラック型エポキシ樹脂、ビスフェノール型エポキシ樹脂、スチルベン型エポキシ樹脂、トリフェノールメタン型エポキシ樹脂、フェノールアラルキル型エポキシ樹脂、ナフトール型エポキシ樹脂、ジシクロペンタジエン型エポキシ樹脂、トリフェニルメタン型エポキシ樹脂などを用いることができる。これらは単独でも、２種以上を組み合わせて用いてもよい。また、アクリル樹脂など他の有機樹脂と適宜組み合わせて使用してもよい。 The liquid epoxy resin is not particularly limited as long as it has fluidity at room temperature, and all commercially available epoxy resins can be used. Specific examples of such epoxy resins include naphthalene type epoxy resins, biphenyl type epoxy resins, phenol novolac type epoxy resins, bisphenol type epoxy resins, stilbene type epoxy resins, triphenolmethane type epoxy resins, phenol aralkyl type epoxy resins. Resins, naphthol type epoxy resins, dicyclopentadiene type epoxy resins, triphenylmethane type epoxy resins, and the like can be used. These may be used alone or in combination of two or more. Moreover, you may use it combining suitably with other organic resins, such as an acrylic resin.
　潜在性硬化剤としては、加熱硬化型、ＵＶ硬化型などの各種硬化剤が使用できる。潜在性硬化剤は、通常では反応せず、何かしらのトリガーにより活性化し、反応を開始する。トリガーには、熱、光、加圧などがあり、用途により選択して用いることができる。なかでも、本願では、加熱硬化型の潜在性硬化剤が好適に用いられ、バスバー電極１１や裏面電極１３に加熱押圧されることにより本硬化される。液状エポキシ樹脂を使用する場合は、イミダゾール類、アミン類、スルホニウム塩、オニウム塩などからなる潜在性硬化剤を使用することができる。 As the latent curing agent, various curing agents such as a heat curing type and a UV curing type can be used. The latent curing agent does not normally react but is activated by some trigger and starts the reaction. The trigger includes heat, light, pressurization, etc., and can be selected and used depending on the application. Among these, in the present application, a thermosetting latent curing agent is suitably used, and the main curing is performed by heating and pressing the bus bar electrode 11 and the back electrode 13. When using a liquid epoxy resin, a latent curing agent composed of imidazoles, amines, sulfonium salts, onium salts and the like can be used.
　シランカップリング剤としては、エポキシ系、アミノ系、メルカプト・スルフィド系、ウレイド系などを用いることができる。これらの中でも、本実施の形態では、エポキシ系シランカップリング剤が好ましく用いられる。これにより、有機材料と無機材料の界面における接着性を向上させることができる。 As the silane coupling agent, epoxy, amino, mercapto sulfide, ureido, etc. can be used. Among these, in this Embodiment, an epoxy-type silane coupling agent is used preferably. Thereby, the adhesiveness in the interface of an organic material and an inorganic material can be improved.
　また、その他の添加組成物として、無機フィラーを含有することが好ましい。無機フィラーを含有することにより、圧着時における樹脂層の流動性を調整し、粒子捕捉率を向上させることができる。無機フィラーとしては、シリカ、タルク、酸化チタン、炭酸カルシウム、酸化マグネシウム等を用いることができ、無機フィラーの種類は特に限定されるものではない。 Moreover, it is preferable to contain an inorganic filler as another additive composition. By containing an inorganic filler, the fluidity of the resin layer during pressure bonding can be adjusted, and the particle capture rate can be improved. As the inorganic filler, silica, talc, titanium oxide, calcium carbonate, magnesium oxide and the like can be used, and the kind of the inorganic filler is not particularly limited.
　図６は、導電性接着フィルム１７の製品形態の一例を模式的に示す図である。この導電性接着フィルム１７は、剥離基材２７上にバインダー樹脂２２が積層され、テープ状に成型されている。このテープ状の導電性接着フィルムは、リール２６に剥離基材２７が外周側となるように巻回積層される。剥離基材２７としては、特に制限はなく、ＰＥＴ（Poly Ethylene Terephthalate）、ＯＰＰ（Oriented Polypropylene）、ＰＭＰ（Poly-4-methlpentene－1）、ＰＴＦＥ（Polytetrafluoroethylene）などを用いることができる。 FIG. 6 is a diagram schematically showing an example of a product form of the conductive adhesive film 17. The conductive adhesive film 17 is formed in a tape shape by laminating a binder resin 22 on a peeling substrate 27. This tape-like conductive adhesive film is wound and laminated on the reel 26 so that the peeling substrate 27 is on the outer peripheral side. The release substrate 27 is not particularly limited, and PET (Poly Ethylene Terephthalate), OPP (Oriented Polypropylene), PMP (Poly-4-methlpentene-1), PTFE (Polytetrafluoroethylene), and the like can be used.
　また、導電性接着フィルム１７は、バインダー樹脂２２上に透明なカバーフィルムを有する構成としてもよい。このとき、バインダー樹脂２２上に貼付されるカバーフィルムとして上述したタブ線３を用いてもよい。導電性接着フィルム１７は、バインダー樹脂２２がタブ線３の一主面に積層される。このように、予めタブ線３と導電性接着フィルム１７とを積層一体化させておくことにより、実使用時においては、剥離基材２７を剥離し、導電性接着フィルム１７のバインダー樹脂２２をバスバー電極１１や裏面電極１３のタブ線接続部１４上に貼着することによりタブ線３と各電極１１，１３との接続が図られる。 Further, the conductive adhesive film 17 may have a transparent cover film on the binder resin 22. At this time, you may use the tab wire 3 mentioned above as a cover film affixed on the binder resin 22. FIG. In the conductive adhesive film 17, the binder resin 22 is laminated on one main surface of the tab wire 3. As described above, the tab wire 3 and the conductive adhesive film 17 are laminated and integrated in advance, whereby the peeling base material 27 is peeled off during actual use, and the binder resin 22 of the conductive adhesive film 17 is transferred to the bus bar. The tab wire 3 is connected to the electrodes 11 and 13 by sticking on the tab wire connecting portion 14 of the electrode 11 and the back electrode 13.
　上記では、フィルム形状を有する導電性接着フィルムについて説明したが、ペースト状であっても問題は無い。本願では、ハンダ粒子２３を含有するフィルム状の導電性接着フィルム１７やハンダ粒子２３を含有するペースト状の導電性接着ペーストを「導電性接着剤」と定義する。 In the above description, the conductive adhesive film having a film shape has been described, but there is no problem even if it is in a paste form. In the present application, the film-like conductive adhesive film 17 containing the solder particles 23 and the paste-like conductive adhesive paste containing the solder particles 23 are defined as “conductive adhesive”.
　なお、導電性接着フィルム１７は、リール形状に限らず、バスバー電極１１や裏面電極１３のタブ線接続部１４の形状に応じた短冊形状であってもよい。 The conductive adhesive film 17 is not limited to a reel shape, but may be a strip shape corresponding to the shape of the tab wire connection portion 14 of the bus bar electrode 11 or the back electrode 13.
　導電性接着フィルム１７は、図６に示すように巻き取られたリール製品として提供される場合、導電性接着フィルム１７の粘度が１０～１００００ｋＰａ・ｓであることが好ましく、さらに１０～５０００ｋＰａ・ｓの範囲とすることが好ましい。これにより、導電性接着フィルム１７は、リール状に巻装した場合において、いわゆるはみ出しによるブロッキングを防止することができ、また、所定のタック力を維持することができる。また、導電性接着フィルム１７は、変形が防止され、所定の寸法を維持することができる。さらに、導電性接着フィルム１７は、短冊形状で２枚以上積層された場合も同様に、変形を防止し、所定の寸法を維持することができる。 When the conductive adhesive film 17 is provided as a reel product wound as shown in FIG. 6, the conductive adhesive film 17 preferably has a viscosity of 10 to 10000 kPa · s, more preferably 10 to 5000 kPa · s. It is preferable to set it as the range. Thereby, when the conductive adhesive film 17 is wound in a reel shape, blocking due to the so-called protrusion can be prevented, and a predetermined tack force can be maintained. Further, the conductive adhesive film 17 is prevented from being deformed and can maintain a predetermined dimension. Further, when two or more conductive adhesive films 17 are stacked in a strip shape, the conductive adhesive film 17 can similarly prevent deformation and maintain a predetermined dimension.
　［製造方法］
　上述した導電性接着フィルム１７は、ハンダ粒子２３と、膜形成樹脂と、液状エポキシ樹脂と、潜在性硬化剤と、シランカップリング剤とを溶剤に溶解させる。溶剤としては、トルエン、酢酸エチルなど、又はこれらの混合溶剤を用いることができる。溶解させて得られた樹脂生成用溶液を剥離シート上に塗布し、溶剤を揮発させることにより、導電性接着フィルム１７を得る。 [Production method]
The conductive adhesive film 17 described above dissolves the solder particles 23, the film-forming resin, the liquid epoxy resin, the latent curing agent, and the silane coupling agent in a solvent. As the solvent, toluene, ethyl acetate or the like, or a mixed solvent thereof can be used. A conductive adhesive film 17 is obtained by applying a resin-generating solution obtained by dissolution onto a release sheet and volatilizing the solvent.
　そして、導電性接着フィルム１７は、表面電極用２本及び裏面電極用２本を所定の長さにカットされ、太陽電池セル２の表裏面の所定位置に仮貼りされる。このとき、導電性接着フィルム１７は、太陽電池セル２の表面にほぼ平行に複数形成されている各バスバー電極１１及び裏面電極１３のタブ線接続部１４上に仮貼りされる。なお、導電性接着剤として導電性接着ペーストを用いる場合は、バスバー電極１１及び裏面電極１３のタブ線接続部１４上に導電性接着ペーストが塗布される。 Then, the conductive adhesive film 17 is cut into a predetermined length for two of the front electrode and two for the back electrode, and is temporarily attached to a predetermined position on the front and back surfaces of the solar battery cell 2. At this time, the conductive adhesive film 17 is temporarily pasted on the tab line connecting portions 14 of the bus bar electrodes 11 and the back electrode 13 that are formed in plural substantially parallel to the surface of the solar battery cell 2. In the case where a conductive adhesive paste is used as the conductive adhesive, the conductive adhesive paste is applied on the tab line connecting portions 14 of the bus bar electrode 11 and the back electrode 13.
　次いで、同様に所定の長さにカットされたタブ線３が導電性接着フィルム１７上に重畳配置される。その後、導電性接着フィルム１７は、タブ線３の上から加熱ボンダーによって所定の温度、圧力で熱加圧されることにより、余剰のバインダー樹脂２２が各電極１１，１３とタブ線３との間より流出されるとともにハンダ粒子２３がタブ線３と各電極１１，１３との間で挟持され、この状態でバインダー樹脂２２が硬化する。 Next, the tab wire 3 similarly cut to a predetermined length is placed on the conductive adhesive film 17 in an overlapping manner. Thereafter, the conductive adhesive film 17 is heated and pressed at a predetermined temperature and pressure from above the tab wire 3 by a heating bonder, so that the excess binder resin 22 is placed between the electrodes 11 and 13 and the tab wire 3. The solder particles 23 are sandwiched between the tab wire 3 and the electrodes 11 and 13 and the binder resin 22 is cured in this state.
　ここで、加熱ボンダーによるタブ線３の熱加圧条件は、導電性接着フィルム１７のバインダー樹脂２２が熱硬化するとともに、外層２５がタブ線３及び電極１１，１３と金属結合し、かつ内層２４が溶融しないための条件であり、バインダー樹脂２２やハンダ粒子２３の組成等に応じて適宜設定される。例えば、加熱ボンダーによるタブ線３の熱加圧条件は、内層２４の融点より低く、外層２５の融点以上の温度に設定される。これにより、導電性接着フィルム１７は、バインダー樹脂２２によってタブ線３を各電極１１，１３上に接着させると共に、ハンダ粒子２３の外層２５がバスバー電極１１や裏面電極１３に金属結合し、硬い内層２４によって両者を導通接続させることができる。 Here, the heat pressurizing condition of the tab wire 3 by the heating bonder is that the binder resin 22 of the conductive adhesive film 17 is thermally cured, the outer layer 25 is metal-bonded to the tab wire 3 and the electrodes 11, 13, and the inner layer 24. Is a condition for preventing melting, and is appropriately set according to the composition of the binder resin 22 and the solder particles 23. For example, the thermal pressing condition of the tab wire 3 by the heating bonder is set to a temperature lower than the melting point of the inner layer 24 and higher than the melting point of the outer layer 25. As a result, the conductive adhesive film 17 adheres the tab wire 3 to the electrodes 11 and 13 by the binder resin 22, and the outer layer 25 of the solder particles 23 is metal-bonded to the bus bar electrode 11 and the back electrode 13, thereby forming a hard inner layer. 24 can be connected to each other.
　このとき、ハンダ粒子２３は、タブ線３及び電極１１，１３に接する外層２５が溶融することによりフラックス機能を奏することから、酸化した表面を除去し、内層２４とタブ線３及び電極１１，１３との接続信頼性を向上させることができる。 At this time, the solder particles 23 have a flux function by melting the outer layer 25 in contact with the tab wire 3 and the electrodes 11, 13, so the oxidized surface is removed, and the inner layer 24, the tab wire 3 and the electrodes 11, 13 are removed. Connection reliability can be improved.
　このようにして、太陽電池セル２を順次タブ線３によって接続し、ストリングス４、マトリクス５を形成していく。次いで、マトリクス５を構成する複数の太陽電池セル２は、ガラス、透光性プラスチックなどの透光性を有する表面カバー７と、ガラスやＰＥＴ（Poly Ethylene Terephthalate）フィルム等からなるバックシート８との間に、エチレンビニルアセテート樹脂（ＥＶＡ）等の透光性を有する封止材のシート６により封止される。最後に、周囲にアルミニウムなどの金属フレーム９が取り付けられることにより太陽電池モジュール１が形成される。 In this way, the solar cells 2 are sequentially connected by the tab wires 3 to form the strings 4 and the matrix 5. Next, the plurality of solar cells 2 constituting the matrix 5 are made up of a surface cover 7 having translucency such as glass and translucent plastic, and a back sheet 8 made of glass or PET (Poly Ethylene Terephthalate) film. In between, it seals with the sheet | seat 6 of the sealing material which has translucency, such as ethylene vinyl acetate resin (EVA). Finally, the solar cell module 1 is formed by attaching a metal frame 9 such as aluminum around the periphery.
　［バスバーレス］
　なお、太陽電池モジュール１は、上述したように、太陽電池セル２の受光面側にフィンガー電極１２と略直交するバスバー電極１１を設け、当該バスバー電極１１上に導電性接着剤及びタブ線３を積層させる構成の他、バスバー電極１１を設けることなく、フィンガー電極１２と直交するように導電性接着剤及びタブ線３を積層させるいわゆるバスバーレス構造としてもよい。この場合、導電性接着フィルム１７は、ハンダ粒子２３の外層２５がフィンガー電極１２との間で金属結合するとともに、内層２４がタブ線３とフィンガー電極１２との間に挟持される。 [Bus Barless]
As described above, the solar cell module 1 is provided with the bus bar electrode 11 substantially orthogonal to the finger electrode 12 on the light receiving surface side of the solar cell 2, and the conductive adhesive and the tab wire 3 are provided on the bus bar electrode 11. In addition to the configuration of laminating, a so-called bus bar-less structure in which the conductive adhesive and the tab wire 3 are laminated so as to be orthogonal to the finger electrode 12 without providing the bus bar electrode 11 may be employed. In this case, in the conductive adhesive film 17, the outer layer 25 of the solder particles 23 is metal-bonded with the finger electrode 12, and the inner layer 24 is sandwiched between the tab wire 3 and the finger electrode 12.
　［一括ラミネート］
　また、太陽電池モジュール１は、上述したように太陽電池セル２の各電極１１，１３上に導電性接着剤及びタブ線３を配置した後、加熱ボンダーによってタブ線３上を熱加圧させる工法の他、太陽電池セル２の表面及び裏面に導電性接着剤、タブ線３及び太陽電池セル２を封止するＥＶＡ等の透光性封止材シートを順次積層させ、減圧ラミネータを用いてこれをガラスやＰＥＴフィルムで一括してラミネート処理を行うことにより、タブ線３を各電極１１，１３上に熱加圧してもよい。 [Batch lamination]
Moreover, the solar cell module 1 arrange | positions a conductive adhesive and the tab wire 3 on each electrode 11 and 13 of the photovoltaic cell 2 as mentioned above, Then, the construction method which heat-presses on the tab wire 3 with a heating bonder. In addition, a conductive adhesive, a tab wire 3 and a light-transmitting sealing material sheet such as EVA that seals the solar battery cell 2 are sequentially laminated on the front and back surfaces of the solar battery cell 2, and this is reduced using a reduced pressure laminator. The tab wire 3 may be heat-pressed on each of the electrodes 11 and 13 by performing a laminating process with glass or PET film.
　［太陽電池モジュールの効果］
　このような太陽電池モジュール１は、導電性接着フィルム１７のハンダ粒子２３の外層２５がタブ線３及び太陽電池セル２の電極１１、１３と金属結合するとともに硬い内層２４がタブ線３及び電極１１，１３に挟持されている。したがって、タブ線３の接続強度を向上させることができ、また、高温多湿の使用環境下に繰り返し曝された場合にも、ハンダ粒子２３とタブ線３及び電極１１，１３との電気的な接続信頼性を維持し、発電効率の低下を防止することができる。 [Effect of solar cell module]
In such a solar cell module 1, the outer layer 25 of the solder particles 23 of the conductive adhesive film 17 is metal-bonded to the tab wire 3 and the electrodes 11 and 13 of the solar cell 2, and the hard inner layer 24 is the tab wire 3 and the electrode 11. , 13. Therefore, the connection strength of the tab wire 3 can be improved, and the electrical connection between the solder particles 23 and the tab wire 3 and the electrodes 11 and 13 even when repeatedly exposed to a high temperature and high humidity environment. It is possible to maintain reliability and prevent a decrease in power generation efficiency.
　なお、太陽電池モジュール１は、タブ線３を、平角銅線や銅箔にハンダ粒子２３の外層２５と同種のハンダにてコーティングを施して形成してもよい。これにより、太陽電池モジュール１は、ハンダ粒子２３の外層２５とタブ線３との金属結合をより確実に形成し、タブ線３の電極１１，１３への接着力や導通信頼性をさらに向上させることができる。 Note that the solar cell module 1 may be formed by coating the tab wire 3 with a flat copper wire or copper foil with the same kind of solder as the outer layer 25 of the solder particles 23. Thereby, the solar cell module 1 more reliably forms a metal bond between the outer layer 25 of the solder particles 23 and the tab wire 3, and further improves the adhesive force and conduction reliability of the tab wire 3 to the electrodes 11 and 13. be able to.
　次いで、本発明の実施例について説明する。図７に示すように、本実施例は、バインダー樹脂に含有するハンダ粒子の層構成（１層又は２層）及び内層組成及び外層組成が異なる複数種類の導電性接着フィルムのサンプル４０を用意した。そして、これら導電性接着フィルムの各サンプル４０を用いて、タブ線４１を表面電極３１及び裏面電極３２が形成された光電変換素子３０の各表面電極３１及び裏面電極３２に２本ずつ熱加圧して接着した。熱加圧条件は、いずれも１８０℃、１０ｓｅｃ、２ＭＰａとした。 Next, examples of the present invention will be described. As shown in FIG. 7, in this example, a plurality of types of conductive adhesive film samples 40 having different layer configurations (one or two layers) of solder particles contained in a binder resin and different inner and outer layer compositions were prepared. . And using each sample 40 of these electroconductive adhesive films, two tab wires 41 are hot-pressed on each front surface electrode 31 and back surface electrode 32 of the photoelectric conversion element 30 on which the front surface electrode 31 and the back surface electrode 32 are formed. And glued. The hot pressing conditions were all 180 ° C., 10 sec, and 2 MPa.
　導電性接着フィルムのサンプル４０は、
フェノキシ樹脂（ＹＰ－５０：新日鐵化学株式会社製）；２０質量部
液状エポキシ樹脂（ＥＰ８２８：三菱化学株式会社製）；５０質量部
ハンダ粒子；１０質量部
イミダゾール系潜在性硬化剤（ＨＸ３９４１ＨＰ：旭化成株式会社製）；２０質量部
トルエン；１００質量部
を混合し樹脂組成物を調整した。 Sample 40 of conductive adhesive film is
Phenoxy resin (YP-50: manufactured by Nippon Steel Chemical Co., Ltd.); 20 parts by mass liquid epoxy resin (EP828: manufactured by Mitsubishi Chemical Corporation); 50 parts by mass solder particles; 10 parts by mass imidazole-based latent curing agent (HX3941HP: Asahi Kasei Corporation); 20 parts by mass toluene; 100 parts by mass was mixed to prepare a resin composition.
　その後、この樹脂組成物を、５０μｍ厚の剥離処理ポリエチレンテレフタレートフィルムに、２５μｍ厚となるように塗布し、８０℃のオーブン中で５分間加熱乾燥処理して成膜することにより導電性接着フィルムのサンプル４０を作成した。タブ線４１は、一般的に用いられるタブ線であり、長尺状の銅箔にハンダメッキを施した２ｍｍ幅、３５μｍ厚のものである。 After that, this resin composition was applied to a 50 μm-thick release-treated polyethylene terephthalate film so as to have a thickness of 25 μm, and heated and dried in an oven at 80 ° C. for 5 minutes to form a film. Sample 40 was created. The tab wire 41 is a tab wire that is generally used, and has a width of 2 mm and a thickness of 35 μm obtained by soldering a long copper foil.
　そして、以下の実施例及び比較例に係る各太陽電池セルについて、初期の導通抵抗（ｍΩ）、高温高湿試験（８５℃８５％ＲＨ×３０００ｈｒ）後の導通抵抗（ｍΩ）、初期接着力（Ｎ／２ｍｍ）を測定した。 And about each photovoltaic cell concerning the following Examples and comparative examples, initial conduction resistance (mΩ), conduction resistance (mΩ) after a high temperature and high humidity test (85 ° C. 85% RH × 3000 hr), initial adhesive force ( N / 2 mm).
　導通抵抗は、２本のタブ線（Ｃｕ箔、２ｍｍ幅、３５μｍ厚）の先端２ｍｍの部分をＡｇ電極（ベタ電極）が形成されたガラス基板上に導電性接着フィルムを用いて熱圧着し（１８０℃、２Ｍｐａ、１０秒）、２本のタブ線間の抵抗をデジタルマルチメータを用いて測定した。 The conduction resistance is thermocompression-bonded using a conductive adhesive film on a glass substrate on which an Ag electrode (solid electrode) is formed at the tip 2 mm of two tab wires (Cu foil, 2 mm width, 35 μm thickness) ( 180 ° C., 2 Mpa, 10 seconds) The resistance between the two tab wires was measured using a digital multimeter.
　初期接着力は、タブ線を表面電極３１、裏面電極３２のそれぞれに接着された導電性接着フィルムから９０°方向で剥離する９０°剥離試験（ＪＩＳ　Ｋ６８５４－１）を行い、ピール強度（Ｎ／２ｍｍ）を測定した。 The initial adhesive strength was determined by performing a 90 ° peel test (JIS K6854-1) to peel the tab wire from the conductive adhesive film bonded to each of the front electrode 31 and the back electrode 32 in a 90 ° direction, and peel strength (N / 2 mm).
　実施例１は、内層をＳｎ－Ａｇ－Ｃｕ系ハンダ（融点：２２０℃）で構成し、外層をＳｎ－Ｂｉ系ハンダ（融点：１４１℃）で構成したハンダ粒子を用いた。ハンダ粒子の平均粒子径は３０μｍである。 Example 1 used solder particles in which the inner layer was composed of Sn—Ag—Cu solder (melting point: 220 ° C.) and the outer layer was composed of Sn—Bi solder (melting point: 141 ° C.). The average particle diameter of the solder particles is 30 μm.
　実施例２は、内層をＳｎ－Ｐｂ系ハンダ（融点：１８４℃）で構成し、外層をＳｎ－Ｂｉ系ハンダ（融点：１４１℃）で構成したハンダ粒子を用いた。ハンダ粒子の平均粒子径は３０μｍである。 Example 2 used solder particles in which the inner layer was composed of Sn—Pb solder (melting point: 184 ° C.) and the outer layer was composed of Sn—Bi solder (melting point: 141 ° C.). The average particle diameter of the solder particles is 30 μm.
　実施例３は、ハンダ粒子の平均粒子径を２０μｍとした以外は、実施例２と同じハンダ粒子を用いた。 Example 3 used the same solder particles as in Example 2 except that the average particle diameter of the solder particles was 20 μm.
　実施例４は、ハンダ粒子の平均粒子径を５０μｍとした以外は、実施例２と同じハンダ粒子を用いた。 Example 4 used the same solder particles as in Example 2 except that the average particle diameter of the solder particles was 50 μm.
　比較例１は、Ｓｎ－Ｐｂ系ハンダ（融点：１８４℃）の１層のみで構成されたハンダ粒子を用いた。ハンダ粒子の平均粒子径は３０μｍである。 Comparative Example 1 used solder particles composed of only one layer of Sn—Pb solder (melting point: 184 ° C.). The average particle diameter of the solder particles is 30 μm.
　比較例２は、Ｓｎ－Ａｇ－Ｃｕ系ハンダ（融点：２２０℃）の１層のみで構成されたハンダ粒子を用いた。ハンダ粒子の平均粒子径は３０μｍである。 Comparative Example 2 used solder particles composed of only one layer of Sn—Ag—Cu solder (melting point: 220 ° C.). The average particle diameter of the solder particles is 30 μm.
　比較例３は、Ｓｎ－Ｂｉ系ハンダ（融点：１４１℃）の１層のみで構成されたハンダ粒子を用いた。ハンダ粒子の平均粒子径は３０μｍである。 Comparative Example 3 used solder particles composed of only one layer of Sn—Bi solder (melting point: 141 ° C.). The average particle diameter of the solder particles is 30 μm.
　比較例４は、内層をＳｎ－Ｐｂ系ハンダ（融点：１８４℃）で構成し、外層をＳｎ－Ａｇ－Ｃｕ系ハンダ（融点：２２０℃）で構成したハンダ粒子を用いた。ハンダ粒子の平均粒子径は３０μｍである。 Comparative Example 4 used solder particles in which the inner layer was composed of Sn—Pb solder (melting point: 184 ° C.) and the outer layer was composed of Sn—Ag—Cu solder (melting point: 220 ° C.). The average particle diameter of the solder particles is 30 μm.
　比較例５は、ハンダ粒子に代えて、内層を樹脂で構成し、外層をＮｉ－Ａｕメッキでコーティングしたメッキ付き樹脂を用いた。 In Comparative Example 5, instead of the solder particles, a plated resin in which the inner layer is made of resin and the outer layer is coated with Ni—Au plating was used.
　実施例１～４、比較例１～５に係る各太陽電池セルについて、初期の導通抵抗（ｍΩ）及び高温高湿試験（８５℃８５％ＲＨ×３０００ｈｒ）後の導通抵抗（ｍΩ）を測定した。さらに、タブ線３と電極３１，３２との初期接着力（Ｎ／２ｍｍ）を測定した。初期接着力は、９０°引き剥がしのピール強度を、引っ張り速度３０ｍｍ／ｍｉｎの条件にて測定した。 For each of the solar cells according to Examples 1 to 4 and Comparative Examples 1 to 5, the initial conduction resistance (mΩ) and the conduction resistance (mΩ) after a high temperature and high humidity test (85 ° C., 85% RH × 3000 hr) were measured. . Furthermore, the initial adhesive force (N / 2 mm) between the tab wire 3 and the electrodes 31 and 32 was measured. The initial adhesive strength was measured by peeling the 90 ° peel strength under conditions of a pulling speed of 30 mm / min.
　結果を表１に示す。評価の指標として、初期の導通抵抗（ｍΩ）及び高温高湿試験（８５℃８５％ＲＨ×３０００ｈｒ）後の導通抵抗（ｍΩ）、初期接着力（Ｎ／２ｍｍ）を総合して考慮し、実用に耐えられるものを○、導通抵抗又は接着力のいずれかが実用に耐えられないものを△、導通抵抗及び接着力のいずれも実用に耐えられないものを×とした。 The results are shown in Table 1. As an evaluation index, the initial conduction resistance (mΩ), the conduction resistance (mΩ) after the high-temperature and high-humidity test (85 ° C., 85% RH × 3000 hr), and the initial adhesive strength (N / 2 mm) are comprehensively considered. ◯ for those that could withstand the resistance, Δ for any of the conduction resistance or adhesive strength that could not withstand practical use, and × for those that could not withstand any of the conduction resistance or adhesive strength practical.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示すように、実施例１～４では、いずれも初期の導通抵抗が１０ｍΩ以下であり導通性に問題はなく、高温高湿試験（８５℃８５％ＲＨ×３０００ｈｒ）後の導通抵抗も２５ｍΩ以下と、導通信頼性が高く維持されている。一方、比較例１～４では、初期の導通抵抗が１５ｍΩ以下ではあるが、高温高湿試験（８５℃８５％ＲＨ×３０００ｈｒ）後の導通抵抗が測定することができず導通不良となり（オープン）、導通信頼性が悪かった。 As shown in Table 1, in each of Examples 1 to 4, the initial conduction resistance was 10 mΩ or less, and there was no problem in conduction, and the conduction resistance after the high-temperature and high-humidity test (85 ° C., 85% RH × 3000 hr) The conduction reliability is kept high at 25 mΩ or less. On the other hand, in Comparative Examples 1 to 4, although the initial conduction resistance is 15 mΩ or less, the conduction resistance after the high-temperature and high-humidity test (85 ° C., 85% RH × 3000 hr) cannot be measured, resulting in poor conduction (open). The conduction reliability was bad.
　また、実施例１～４では、いずれも初期の接着力が５Ｎ／２ｍｍ以上と高い接着力を有する。一方、比較例１～４では、初期の接着力が５Ｎ／２ｍｍ以下と接着力が低かった。 In Examples 1 to 4, the initial adhesive strength is as high as 5 N / 2 mm or more. On the other hand, in Comparative Examples 1 to 4, the initial adhesive strength was as low as 5 N / 2 mm or less.
　これは、実施例１～４では、内層及び外層からなる多層構造であり、内層を構成するハンダの融点が、外層を構成するハンダの融点よりも高く構成されているため、熱加圧工程において、ハンダ粒子の外層がタブ線及び電極３１、３２と金属結合するとともに硬い内層がタブ線及び電極３１，３２に挟持されるためである。以上より、実施例１～４によれば、導通抵抗及び接着力いずれの面でも実用に耐えられるものであることが分かる。 This is a multilayer structure composed of an inner layer and an outer layer in Examples 1 to 4, and the melting point of the solder constituting the inner layer is higher than the melting point of the solder constituting the outer layer. This is because the outer layer of the solder particles is metal-bonded to the tab wire and the electrodes 31 and 32 and the hard inner layer is sandwiched between the tab wire and the electrodes 31 and 32. From the above, according to Examples 1 to 4, it can be seen that both the conduction resistance and the adhesive strength can withstand practical use.
　一方、多層構造を有さない比較例１、比較例２では、ハンダ粒子とタブ線及び電極３１，３２との間に金属結合を形成せず、また比較例３ではハンダ粒子が溶融しタブ線と電極３１，３２との間で挟持されなくなったため、高温高湿試験において接続不良が見られた。また、多層構造を有する比較例４では、外層が内層よりも高融点ハンダで構成されているため、外層とタブ線及び電極３１，３２とが金属結合を形成せず、高温高湿試験において接続不良が見られた。ハンダ粒子に代えてメッキ付き樹脂を用いた比較例５では、接着力が弱く、また、高温高湿試験において、導通抵抗の上昇が見られた。 On the other hand, in Comparative Example 1 and Comparative Example 2 that do not have a multilayer structure, no metal bond is formed between the solder particles and the tab wires and the electrodes 31 and 32. In Comparative Example 3, the solder particles are melted and the tab wires are melted. Between the electrode 31 and the electrode 31 and 32, connection failure was observed in the high-temperature and high-humidity test. In Comparative Example 4 having a multilayer structure, since the outer layer is made of higher melting point solder than the inner layer, the outer layer and the tab wires and the electrodes 31 and 32 do not form a metal bond and are connected in a high-temperature and high-humidity test. Defects were seen. In Comparative Example 5 in which a plated resin was used instead of the solder particles, the adhesive strength was weak, and an increase in conduction resistance was observed in the high temperature and high humidity test.
１　太陽電池モジュール、２　太陽電池セル、３　タブ線、４　ストリングス、５　マトリクス、６　シート、７　表面カバー、８　バックシート、９　金属フレーム、１０　光電変換素子、１１　バスバー電極、１２　フィンガー電極、１３　裏面電極、１４　タブ線接続部、１７　導電性接着フィルム、２２　バインダー樹脂、２３　ハンダ粒子、２４　内層、２５　外層、２６リール、２７　剥離基材、３０　光電変換素子、３１　表面電極、３２　裏面電極、４０　サンプル 1 solar cell module, 2 solar cell, 3 tab wire, 4 strings, 5 matrix, 6 sheet, 7 surface cover, 8 back sheet, 9 metal frame, 10 photoelectric conversion element, 11 bus bar electrode, 12 finger electrode, 13 back surface Electrode, 14 tab wire connection part, 17 conductive adhesive film, 22 binder resin, 23 solder particles, 24 inner layer, 25 outer layer, 26 reel, 27 peeling substrate, 30 photoelectric conversion element, 31 surface electrode, 32 back electrode, 40 sample

Claims (15)

  1. 　複数の太陽電池セルと、上記太陽電池セルの表面及び隣接する太陽電池セルの裏面にそれぞれ形成された電極上に導電性粒子を含有する熱硬化性の導電性接着剤を介して接着され、複数の上記太陽電池セル同士を接続するタブ線とを備え、
    　上記導電性接着剤にはハンダ粒子が含有され、
    　上記ハンダ粒子は、少なくとも内層及び外層からなる多層構造であり、上記内層を構成するハンダの融点が、上記外層を構成するハンダの融点よりも高い太陽電池モジュール。     The plurality of solar cells are bonded to each of the electrodes formed on the surface of the solar cell and the back surface of the adjacent solar cell via a thermosetting conductive adhesive containing conductive particles. And a tab wire for connecting the solar cells to each other,
    The conductive adhesive contains solder particles,
    The solder particles have a multilayer structure composed of at least an inner layer and an outer layer, and the melting point of the solder constituting the inner layer is higher than the melting point of the solder constituting the outer layer.
  2. 　上記ハンダ粒子は、内層を構成するハンダの融点が、上記導電性接着剤のバインダー樹脂の硬化温度よりも高い請求項１記載の太陽電池モジュール。 The solar cell module according to claim 1, wherein the solder particles have a melting point of the solder constituting the inner layer higher than the curing temperature of the binder resin of the conductive adhesive.
  3. 　上記ハンダ粒子は、外層を構成するハンダの融点が、上記導電性接着剤のバインダー樹脂の硬化温度以下である請求項１又は請求項２に記載の太陽電池モジュール。 3. The solar cell module according to claim 1, wherein the solder particles have a melting point of solder constituting the outer layer equal to or lower than a curing temperature of the binder resin of the conductive adhesive.
  4. 　上記ハンダ粒子は、内層及び外層からなる２層構造である請求項１～請求項３のいずれか１項に記載の太陽電池モジュール。 The solar cell module according to any one of claims 1 to 3, wherein the solder particles have a two-layer structure including an inner layer and an outer layer.
  5. 　上記ハンダ粒子の粒子径が２０～５０μｍである請求項１～請求項４のいずれか１項に記載の太陽電池モジュール。 The solar cell module according to any one of claims 1 to 4, wherein a particle diameter of the solder particles is 20 to 50 µm.
  6. 　上記内層を構成するハンダはＳｎ－Ａｇ－Ｃｕ系ハンダ、又はＳｎ－Ｐｂ系ハンダであり、
    　上記外層を構成するハンダはＳｎ－Ｂｉ系ハンダである請求項１～請求項５のいずれか１項に記載の太陽電池モジュール。     The solder constituting the inner layer is Sn—Ag—Cu solder, or Sn—Pb solder,
    The solar cell module according to any one of claims 1 to 5, wherein the solder constituting the outer layer is Sn-Bi solder.
  7. 　太陽電池セルの表面電極に導電性粒子を含有する熱硬化性の導電性接着剤を介してタブ線の一端側を配置し、上記太陽電池セルと隣接する太陽電池セルの裏面電極に導電性粒子を含有する熱硬化性の導電性接着剤を介して上記タブ線の他端側を配置する工程と、
    　上記タブ線を上記表面電極及び上記裏面電極へ熱加圧し、上記導電性接着剤によって上記タブ線を上記表面電極及び上記裏面電極へ接着する工程とを有し、
    　上記導電性接着剤にはハンダ粒子が含有され、
    　上記ハンダ粒子は、少なくとも内層及び外層からなる多層構造であり、上記内層を構成するハンダの融点が、上記外層を構成するハンダの融点よりも高い太陽電池モジュールの製造方法。     One end side of the tab wire is arranged on the surface electrode of the solar battery cell via a thermosetting conductive adhesive containing conductive particles, and the conductive particle is placed on the back electrode of the solar battery cell adjacent to the solar battery cell. Placing the other end of the tab wire through a thermosetting conductive adhesive containing:
    Heat-pressing the tab wire to the front electrode and the back electrode, and bonding the tab wire to the front electrode and the back electrode with the conductive adhesive,
    The conductive adhesive contains solder particles,
    The solder particles have a multilayer structure including at least an inner layer and an outer layer, and the melting point of the solder constituting the inner layer is higher than the melting point of the solder constituting the outer layer.
  8. 　上記ハンダ粒子は、内層を構成するハンダの融点が、上記熱加圧温度よりも高い請求項７記載の太陽電池モジュールの製造方法。 The said solder particle is a manufacturing method of the solar cell module of Claim 7 whose melting | fusing point of the solder which comprises an inner layer is higher than the said heat pressurization temperature.
  9. 　上記ハンダ粒子は、外層を構成するハンダの融点が、上記熱加圧温度以下である請求項７又は請求項８に記載の太陽電池モジュールの製造方法。 The method for manufacturing a solar cell module according to claim 7 or 8, wherein the solder particles have a melting point of solder constituting the outer layer equal to or lower than the thermal pressurization temperature.
  10. 　上記ハンダ粒子は、内層及び外層からなる２層構造である請求項７～請求項９のいずれか１項に記載の太陽電池モジュールの製造方法。 The method for manufacturing a solar cell module according to any one of claims 7 to 9, wherein the solder particles have a two-layer structure including an inner layer and an outer layer.
  11. 　上記ハンダ粒子の粒子径が２０～５０μｍである請求項７～請求項１０のいずれか１項に記載の太陽電池モジュールの製造方法。 The method for manufacturing a solar cell module according to any one of claims 7 to 10, wherein a particle diameter of the solder particles is 20 to 50 µm.
  12. 　上記内層を構成するハンダはＳｎ－Ａｇ－Ｃｕ系ハンダ、又はＳｎ－Ｐｂ系ハンダであり、
    　上記外層を構成するハンダはＳｎ－Ｂｉ系ハンダである請求項７～請求項１１のいずれか１項に記載の太陽電池モジュールの製造方法。     The solder constituting the inner layer is Sn—Ag—Cu solder, or Sn—Pb solder,
    The method of manufacturing a solar cell module according to any one of claims 7 to 11, wherein the solder constituting the outer layer is Sn-Bi solder.
  13. 　上記タブ線の接着工程は、上記導電性接着剤を介して上記タブ線が上記表面電極及び上記裏面電極上に配置された上記太陽電池セルの両面を透明封止樹脂及び保護材で挟持した後、真空ラミネート及び加熱することにより、上記タブ線を上記表面電極及び上記裏面電極へ接着する請求項７～請求項１２のいずれか１項に記載の太陽電池モジュールの製造方法。 The tab wire adhering step is performed after the tab wire is sandwiched between the transparent battery and the protective material on both sides of the solar cell in which the tab wire is disposed on the front electrode and the back electrode via the conductive adhesive. The method for manufacturing a solar cell module according to any one of claims 7 to 12, wherein the tab wire is bonded to the front electrode and the back electrode by vacuum lamination and heating.
  14. 　太陽電池セルに形成された電極と、複数の上記太陽電池セル同士を接続するタブ線との間に介在され、熱加圧されることにより上記電極と上記タブ線とを接着させる導電性接着剤において、
    　熱硬化性のバインダー樹脂と、上記バインダー樹脂中に含有されたハンダ粒子とを備え、
    　上記ハンダ粒子は、少なくとも内層及び外層からなる多層構造であり、上記内層を構成するハンダの融点が、上記外層を構成するハンダの融点よりも高い導電性接着剤。     A conductive adhesive interposed between the electrode formed in the solar battery cell and the tab wire connecting the plurality of solar battery cells and bonding the electrode and the tab wire by being thermally pressurized. In
    A thermosetting binder resin, and solder particles contained in the binder resin,
    The solder particles have a multilayer structure composed of at least an inner layer and an outer layer, and the melting point of the solder constituting the inner layer is higher than the melting point of the solder constituting the outer layer.
  15. 　フィルム形状である請求項１４記載の導電性接着剤。 The conductive adhesive according to claim 14, which has a film shape.
PCT/JP2012/057790 2011-03-24 2012-03-26 Solar cell module, manufacturing method for solar cell module, and conductive adhesive WO2012128386A1 (en)

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