JP6030924B2 - Conductive adhesive, solar cell module, and method for manufacturing solar cell module - Google Patents

Description

  The present invention relates to a conductive adhesive, and more particularly to a conductive adhesive used for manufacturing a solar cell module, a solar cell module manufactured using the conductive adhesive, and a method for manufacturing a solar cell module using the same.

  In the crystalline silicon solar cell module, a plurality of adjacent solar cells are connected by tab wires made of a ribbon-like copper foil or the like coated with solder 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, the tab wire is bonded to the surface electrode of one solar battery cell on one surface side of one end side, and to the back electrode of the adjacent solar battery cell on the other surface side of the other end side.

  Specifically, the connection between the solar battery cell and the tab wire is made up of a bus bar electrode formed by screen printing of silver paste on the light receiving surface of the solar battery cell, an Ag electrode formed on the back surface connection portion of the solar battery cell, and a tab. The wires are connected by soldering (Patent Document 1). 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.

  However, since soldering is performed at a high temperature of about 260 ° C., the solar cells are warped, the internal stress generated at the connection between the tab wire and the front and back electrodes, the residue of the flux, etc. There is a concern that the connection reliability between the front and back electrodes of the battery cell and the tab wire is lowered.

  Therefore, conventionally, a conductive adhesive film that can be connected by thermocompression treatment at a relatively low temperature is used for connection between 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.

  The conductive adhesive film is interposed between the front electrode and the back electrode and the tab wire, and then thermally pressed from above the tab wire, so that the binder resin exhibits fluidity and between the electrode and the tab wire. As it flows out, the conductive particles conduct between the electrode and the tab wire, and in this state, the binder resin is thermally cured. Thereby, the string by which the several photovoltaic cell was connected in series by the tab wire is formed.

  A plurality of solar cells in which a tab wire and a front electrode and a back electrode are connected using a conductive adhesive film are made of a surface protective material having translucency such as glass and translucent plastic, and PET (Poly Ethylene Terephthalate). ) And the like, and a back protective material made of a film such as ethylene-vinyl acetate copolymer resin (EVA).

  In the thin-film solar cell module, the tab wire is connected to the p-type electrode and the n-type electrode formed on one surface of the solar cell using soldering or a conductive adhesive film.

JP 2004-356349 A JP 2008-135654 A

  Conventionally, nickel filler is mainly used as conductive particles in conductive adhesive films that connect solar cell electrodes and tab wires. However, the surface of the solar cell may be subjected to various types of plating. In such a case, the conductive adhesive containing the conventional nickel filler is not suitable for the adhesive force and the electrode and tab of the solar cell. Connection reliability with the wire may be reduced.

  Then, an object of this invention is to provide the conductive adhesive excellent in adhesive force and connection reliability, the solar cell module manufactured using the same, and the manufacturing method of a solar cell module using the same.

  In order to solve the above-described problem, the conductive adhesive according to the present invention is an electroconductive adhesive that connects an electrode formed on a solar battery cell and a tab wire connecting the plurality of solar battery cells. It contains a curable resin, conductive particles, and a curing agent, and the conductive particles include resin core metal plating particles or metal particles, and the Tg after curing is 140 ° C. or higher.

  Moreover, the solar cell module according to the present invention includes a solar cell, a tab wire connecting the plurality of solar cells, and an electrode provided between the electrode formed on the solar cell and the tab wire. A conductive adhesive layer, the conductive adhesive layer contains at least a curable resin, conductive particles, and a curing agent, and the conductive particles are resin core metal plating particles or metal particles. The Tg after curing of the conductive adhesive layer is 140 ° C. or higher.

  Moreover, the manufacturing method of the solar cell module according to the present invention includes a step of juxtaposing a plurality of solar cells on which electrodes are formed, and a tab wire connecting the plurality of solar cells via a conductive adhesive. The step of temporarily arranging the electrode of the solar battery cell and the tab wire is heated and pressed to cure the conductive adhesive, connect the electrode and the tab wire, and are adjacent to each other via the tab wire. Connecting the solar cells, the conductive adhesive contains at least a curable resin, conductive particles, and a curing agent, the conductive particles are resin core metal plating particles, Or a metal particle is included and Tg after hardening is 140 degreeC or more.

  According to the present invention, by using a conductive adhesive having a Tg of 140 ° C. or higher after curing, the electrodes and tabs of the solar battery cell can be used even under severe and severe usage environments. High connection reliability with the line can be maintained.

It is a disassembled perspective view which shows the structure of the solar cell module to which this invention is applied. It is sectional drawing which shows the string of a photovoltaic cell. It is a bottom view of a photovoltaic cell. It is sectional drawing which shows a conductive adhesive film. It is sectional drawing which shows the electroconductive adhesive film by which the peeling base material was stuck and wound by roll shape. It is a figure which shows the structure of an Example, (A) is a top view, (B) is sectional drawing. It is a figure which shows the structure of an Example, (A) is sectional drawing, (B) is sectional drawing.

  Hereinafter, a conductive adhesive to which the present invention is applied, a solar cell module manufactured using the same, and a method for manufacturing a solar cell module using the same 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 scope of the present invention. Further, the drawings are schematic, and the ratio of each dimension may be different from the actual one. Specific dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  In the following, as a solar cell module, a so-called crystalline silicon solar cell module will be described as an example. However, the present invention is not limited to a silicon solar cell module, but a so-called thin film silicon type, compound type, organic type, quantum dot type, etc. It can be used for various solar cell modules using a conductive adhesive.

[Solar cell module]
The 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, as shown in FIGS. 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.

  As the sealing adhesive, for example, a translucent sealing material such as ethylene-vinyl acetate copolymer 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.

  As shown in FIG. 2, each solar battery cell 2 of the solar battery module has a photoelectric conversion element 10. The photoelectric conversion element 10 is a single crystal silicon type photoelectric conversion element or a polycrystalline silicon type photoelectric conversion element.

  Further, the photoelectric conversion element 10 is provided with finger electrodes 12 serving as surface electrodes for collecting electricity generated inside on the light receiving surface side. The finger electrode 12 is 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. In addition, the finger electrode 12 is formed with a plurality of lines having a width of about 50 to 200 μm, for example, approximately in parallel at a predetermined interval, for example, every 2 mm, over the entire light receiving surface. The finger electrode 12 is appropriately plated on the surface for the purpose of preventing rust.

  The solar battery cell 2 has a so-called bus bar-less structure in which a bus bar electrode for collecting electricity of the finger electrode 12 is not provided by being substantially orthogonal to each finger electrode 12. Therefore, in the solar battery cell 2, a tab wire 3 described later is directly connected to the finger electrode 12 through the conductive adhesive film 17. In the present invention, a solar battery cell in which a bus bar electrode is formed can also be used.

  Further, 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. The back electrode 13 is also appropriately plated on the surface for the purpose of rust prevention or the like.

  And the photovoltaic cell 2 is electrically connected to each finger electrode 12 formed on the surface by the tab wire 3 and the back electrode 13 of the adjacent photovoltaic cell 2, and thereby the strings connected in series. 4 is configured. The tab wire 3, the finger electrode 12 and the back electrode 13 are connected by a conductive adhesive film 17 described later.

[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 subjecting this flat copper wire to gold plating, silver plating, tin plating, solder plating or the like as required.

  The tab wire 3 has one surface 3a as an adhesive surface to the surface on which the finger electrodes 12 of the solar cells 2 are provided, and the other surface 3b as an adhesive surface to the back surface on which the back electrodes 13 of the solar cells 2 are provided. Has been.

[Conductive adhesive]
Next, the conductive adhesive film 17 serving as a conductive adhesive for connecting the tab wire 3 to the front and back surfaces of the solar battery cell 2 will be described. As shown in FIG. 4, the conductive adhesive film 17 is a film in which conductive particles 23 are contained in a thermosetting binder resin 22 at a high density and formed into a film shape. By being interposed between the back surface and the tab wire, a conductive adhesive layer that electrically connects the finger electrode 12 and the back surface electrode 13 to the tab wire is formed.

  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.

  Moreover, it is preferable that the electroconductive adhesive film 17 is 10-10000 kPa * s at the normal temperature vicinity, More preferably, it is 10-5000 kPa * s. When the conductive adhesive film 17 has a viscosity in the range of 10 to 10000 kPa · s, when the conductive adhesive film 17 is provided on the one surface 3a or the other surface 3b of the tab wire 3 and wound around the reel 25, a so-called protrusion is obtained. Can be prevented, and a predetermined tack force can be maintained.

[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 contains at least a curable resin, a curing agent, and conductive particles, and preferably a film. Contains a forming resin and a silane coupling agent.

  The curable resin is not particularly limited as long as it has fluidity at room temperature. For example, a commercially available epoxy resin 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.

  As the curing agent, various latent 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 is fully cured by being heated and pressed by the finger electrode 12 and the back electrode 13. When a liquid epoxy resin is used, a latent curing agent made of imidazoles, amines, sulfonium salts, onium salts, or the like can be used.

  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. .

  As the silane coupling agent, epoxy, amino, mercapto sulfide, ureido, and the like 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.

  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.

  As the binder resin 22 of the conductive adhesive film 17, a resin having a glass transition point (Tg) after curing of 140 ° C. or higher is used, and a binder having a Tg after curing of 150 ° C. to 180 ° C. is particularly preferable. By setting the Tg after curing to 140 ° C. or higher, high connection reliability can be maintained even in a severe and severe usage environment.

  On the other hand, when the Tg after the binder resin 22 is cured is less than 140 ° C., as will be described later, a remarkable increase in the resistance value is observed in the reliability test of the temperature cycle. In addition, although Tg after hardening may be larger than 180 degreeC, since Tg before hardening also becomes large and there exists a possibility of affecting the connection reliability at the time of thermocompression bonding, 180 degreeC or less is more preferable. .

  Further, the conductive adhesive film 17 preferably has a 30 ° C. elastic modulus (E ′) after curing of the binder resin 22 of 1 GPa or more, and particularly preferably 1.3 to 2.0 GPa.

  The conductive adhesive film 17 preferably has a 125 ° C. elastic modulus (E ′) after curing of the binder resin 22 of 0.5 GPa or more, particularly preferably 0.8 to 1.0 GPa.

  When the 30 ° C. elastic modulus (E ′) is less than 1 GPa or the 125 ° C. elastic modulus (E ′) is less than 0.5 GPa, the connection reliability with respect to the temperature cycle and thermal shock is greatly reduced.

  Furthermore, the conductive adhesive film 17 contains a thermoplastic component in the binder resin 22, and the contained thermoplastic component is preferably 35 to 55 wt%, particularly preferably 40 to 50 wt%.

  When the thermoplastic component is less than 35 wt%, the adhesive properties of the binder resin 22 are lowered, and the tab wire 3 is easily peeled off. Moreover, when a thermoplastic component exceeds 50 wt%, an elasticity modulus falls significantly and the connection reliability with respect to a temperature cycle or a thermal shock falls significantly.

[Conductive particles]
As the conductive particles 23 used for the conductive adhesive film 17, resin core metal plating particles or metal particles are used. The metal particles are not particularly limited, and examples thereof include metal particles such as nickel, gold, silver, and copper. Examples of the resin core metal plating particles include particles obtained by applying gold plating or nickel plating to resin particles.

  The conductive particles 23 made of resin core metal plating particles preferably have a 10% compressive strength of 30 to 500 MPa, and more preferably 50 to 400 MPa. When the 10% compressive strength is lower than 30 MPa, the conductive particles 23 made of resin core metal plating particles are too crushed during thermocompression, and when the 10% compressive strength is higher than 500 MPa, they are not crushed sufficiently during thermocompression. For this reason, in any case, the stress due to the difference in the coefficient of linear expansion between the tab wire and the electrode cannot be absorbed by the conductive particles 23, and the conductivity is impaired.

  The conductive particles 23 made of metal particles preferably have a bulk specific gravity / true specific gravity of 0.15 or less, and more preferably 0.05 or more and 0.1 or less. When the bulk specific gravity / true specific gravity is larger than 0.15, the conductive particles 23 made of metal particles have a small amount of conductive particles contained in the binder resin 22 and the particle trapping property is lowered. On the other hand, when the bulk specific gravity / true specific gravity is smaller than 0.04, the amount of conductive particles increases, and the particle pushability decreases. Also in these cases, the stress due to the difference in coefficient of linear expansion between the tab wire and the electrode cannot be absorbed by the conductive particles 23, and the conductivity is impaired.

[Production process of resin core metal plating particles]
Here, as an example of the resin core metal plating particles to be the conductive particles 23, a manufacturing process of gold / nickel coated resin particles will be described. First, a palladium catalyst was supported on 3 μm divinylbenzene resin particles (5 g) by an immersion method. Next, an electroless nickel plating solution (pH 12, plating solution temperature 50 ° C.) prepared from nickel sulfate hexahydrate, sodium hypophosphite, sodium citrate, triethanolamine and thallium nitrate is applied to the resin particles. Electroless nickel plating was used, and nickel-coated resin particles having nickel plating layers (metal layers) having various phosphorus contents formed on the surface were obtained as conductive particles. The average particle diameter of the obtained conductive particles was in the range of 3 to 4 μm.

  An aqueous suspension was prepared by mixing 12 g of the nickel-coated resin particles obtained above with a solution obtained by dissolving 10 g of sodium chloroaurate in 1000 mL of ion-exchanged water. A gold plating bath was prepared by adding 15 g of ammonium thiosulfate, 80 g of ammonium sulfite, and 40 g of ammonium hydrogen phosphate to the obtained aqueous suspension. After adding 4 g of hydroxylamine to the obtained gold plating bath, the pH of the gold plating bath is adjusted to 9 using ammonia, and the bath temperature is maintained at 60 ° C. for about 15 to 20 minutes, whereby gold / nickel coated resin particles Got.

[Production process of metal particles]
Sodium hydroxide and tartaric acid were added to 306 liters of pure water and heated to 65 ° C. with stirring. To this aqueous solution, 39 liters of 60% hydrazine hydrate and 5 kg of nickel chloride aqueous solution with a nickel equivalent amount were added, and nickel was precipitated by a reduction reaction. Next, this liquid was filtered and washed with water to obtain nickel powder. The nickel powder was dried at 80 ° C. and then crushed and classified to obtain various particle sizes.

[Manufacturing process of conductive adhesive film]
FIG. 5 is a diagram schematically illustrating 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 layer on the release substrate 24. This tape-like conductive adhesive film is wound and laminated on the reel 25 so that the peeling substrate 24 is on the outer peripheral side. There is no restriction | limiting in particular as the peeling base material 24, PET (Poly Ethylene Terephthalate), OPP (Oriented Polypropylene), PMP (Poly-4-methlpentene-1), PTFE (Polytetrafluoroethylene) etc. can be used. Further, the conductive adhesive film 17 may have a configuration having a transparent cover film on the binder resin layer.

  At this time, you may use the tab wire 3 mentioned above as a cover film stuck on a binder resin layer. In the conductive adhesive film 17, the binder resin layer is laminated on the one surface 3 a that serves as an adhesive surface of the tab wire 3 to the surface of the solar cell 2 or the other surface 3 b that serves as an adhesive surface to the back surface of the solar cell 2. In this way, the tab wire 3 and the conductive adhesive film 17 are laminated and integrated in advance, so that the peeling substrate 24 is peeled off during actual use, and the binder resin layer of the conductive adhesive film 17 is finger-fed. The tab wire 3 is connected to the electrodes 12 and 13 by sticking on the tab wire connecting portion 14 of the electrode 12 and the back electrode 13.

  In the above description, the conductive adhesive film having a film shape has been described. In the present application, a film-like conductive adhesive film 17 containing conductive particles or a paste-like conductive adhesive paste is defined as a “conductive adhesive”. Even in the case of using a conductive adhesive paste, the tab wire 3 is preliminarily coated with the conductive adhesive paste on one surface 3a which is an adhesive surface to the surface of the solar battery cell 2, and the conductive adhesive is applied to the solar battery. You may affix on each electrode 12 and 13 of the cell 2. FIG.

  The conductive adhesive film 17 is not limited to the reel shape, and may be a strip shape corresponding to the connection region on the surface of the solar battery cell 2 or the shape of the tab wire connection part 14 of the back electrode 13.

  As shown in FIG. 5, when the conductive adhesive film 17 is provided as a reel product wound, the conductive adhesive film 17 has a viscosity of 10 to 10,000 kPa · s, whereby the conductive adhesive film 17 has a viscosity of 10 to 10,000 kPa · s. Deformation can be prevented and a predetermined dimension can be maintained. Similarly, when two or more conductive adhesive films 17 are stacked in a strip shape, deformation can be prevented and a predetermined dimension can be maintained.

[Manufacturing process of solar cell module]
The conductive adhesive film 17 described above dissolves the conductive particles 23, the curable resin, the curing agent, the film forming resin, 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.

  The conductive adhesive film 17 obtained by cutting the two front electrode electrodes and the two back electrode electrodes into a predetermined length is temporarily attached to predetermined positions on the front and back surfaces of the solar battery cell 2. At this time, the conductive adhesive film 17 is temporarily attached so as to cross the plurality of finger electrodes 12 formed substantially parallel to the surface of the solar battery cell 2, and on the tab line connection portion 14 of the back electrode 13. Is temporarily attached.

  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 thermally pressed at a predetermined temperature and pressure from above the tab wire 3 with a heating bonder, whereby the tab wire 3, the finger electrode 12 of the solar battery cell 2, and the back electrode 13. The conductive particles 23 are sandwiched between the tab wire connecting portions 14, and the binder resin is cured in this state.

  Thereby, the solar cell string 4 with which the several photovoltaic cell 2 was connected by the tab wire 3 is formed. A matrix 5 in which a plurality of strings 4 are arranged has a surface cover 7 provided on the light receiving surface side, in which sheets 6 of a light-transmitting sealing adhesive such as EVA for sealing the solar cells 2 are laminated on the front and back surfaces. And it laminates collectively with the back sheet 8 provided in the back surface side, and finally, metal frames 9, such as aluminum, are attached to the circumference | surroundings, and the solar cell module 1 is completed.

  In addition, according to the solar cell module, by using the solar cell 2 having a so-called bus bar-less structure, alignment between the bus bar electrode and the conductive adhesive film 17 and the tab wire 3 becomes unnecessary, thereby reducing the number of manufacturing steps and the number of parts. In addition, the manufacturing cost can be reduced.

[Batch lamination]
In addition, the solar cell module 1 arrange | positions the electroconductive adhesive film 17 and the tab wire 3 on each electrode 12 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 sheet 6 of a light-transmitting sealing adhesive such as EVA that seals the conductive adhesive film 17, the tab wire 3, and the solar battery cell 2 is sequentially laminated on the front and back surfaces of the solar battery cell 2, and the pressure is reduced. While laminating is performed collectively by a laminator, the tab wire 3 may be hot-pressed on the electrodes 12 and 13.

  Next, examples of the present invention will be described. In this embodiment, as shown in FIGS. 6A and 6B, the glass substrate 31 on which aluminum is vapor-deposited on one surface is interposed through conductive adhesive films 33 according to the embodiments and comparative examples described below. On one surface, two tab wires 32 made of solder-coated ribbon-like copper foil were placed in parallel, and EVA 34 and a transparent PET film 35 were laminated and laminated to produce an evaluation connector 30. And about each connection body 30 for evaluation, the conduction resistance of the connection initial stage between each one end part 32a, 32b of two tab wires 32 derived | led-out from the both ends of the connection body 30 for evaluation, and the raise of the conduction resistance after a temperature cycle test The rate was measured.

  For the resistance value, a connection resistance (mΩ) when a current of 1 A was passed by a four-terminal method using a digital multimeter (digital multimeter 7555, manufactured by Yokogawa Electric Corporation) was obtained. The test conditions of the temperature cycle test were as follows: exposure to an atmosphere of −40 ° C. and 100 ° C. for 30 minutes or more, and 200 heat / cool cycles with this as one cycle. In the evaluation shown in Table 1, the case where the initial conduction resistance was less than 25 mΩ was indicated as “◯”, the case where 25 mΩ to 40 mΩ was indicated as “Δ”, and the case where 40 mΩ or more was indicated as “X”. In addition, a case where the rate of increase in conduction resistance after the temperature cycle test was less than 10% was evaluated as ◯, a case where the rate of increase was 10% or more and less than 20%, and a case where the rate of increase was 20% or more.

  Further, in this embodiment, as shown in FIG. 7A, the one surface of the glass substrate 31 coated with Ag paste on one surface through the conductive adhesive films 33 according to the embodiments and comparative examples described below. On the top, two tab wires 32 made of solder-coated ribbon-like copper foil were arranged in parallel, and EVA 34 and PET film 35 were laminated and laminated to produce a connection body 30 for evaluation. And about each connection body 30 for evaluation, after removing PET film and EVA, as shown in FIG.7 (B), the connection strength of the tab wire 32 was measured.

  The connection strength was measured by pulling the tab wire 32 connected to the evaluation connector 30 in a 90 ° direction with respect to the connection surface using a tensile tester (Tenshioron, manufactured by Orientec Corp.). In the evaluation shown in Table 1, ○ when the connection strength is 1.2 N / mm or more, Δ when the connection strength is 0.7 N / mm or more and less than 1.2 N / mm, and less than 0.7 N / mm Was marked with x.

  In each of the examples and comparative examples, when the connection strength, initial conduction resistance, and the rate of increase after the temperature cycle test are all ◯, the overall evaluation is ◯ (good), and when any item is marked △ The evaluation is Δ (normal), and when any item is marked with ×, the overall evaluation is × (defect).

[Examples and comparative examples of resin core metal plating particles]
The conductive adhesive film according to Example 1 has a Tg after curing of 140 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 200 MPa were used.

  The conductive adhesive film according to Example 2 has a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and after curing. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 200 MPa were used.

  The conductive adhesive film according to Example 3 has a Tg after curing of 180 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and after curing. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 200 MPa were used.

  The conductive adhesive film according to Example 4 has, as a binder resin, a Tg after curing of 150 ° C., containing 50 wt% of a thermoplastic component, a 30 ° C. elastic modulus (E ′) after curing of 1.0 GPa, and after curing. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 200 MPa were used.

  The conductive adhesive film according to Example 5 has, as a binder resin, a Tg after curing of 150 ° C., containing 50 wt% of a thermoplastic component, a 30 ° C. elastic modulus (E ′) after curing of 1.3 GPa, and a cured resin The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 200 MPa were used.

  The conductive adhesive film according to Example 6 has a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 2.0 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 200 MPa were used.

  The conductive adhesive film according to Example 7 has a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and after curing. The one with 125 ° C. elastic modulus (E ′) of 0.5 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 200 MPa were used.

  The conductive adhesive film according to Example 8 has a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and after curing. A 125 ° C. elastic modulus (E ′) having 0.8 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 200 MPa were used.

  The conductive adhesive film according to Example 9 has a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and after curing. The one with 125 ° C. elastic modulus (E ′) of 1.0 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 200 MPa were used.

  The conductive adhesive film according to Example 10 has a Tg after curing of 150 ° C. and a thermoplastic component of 35 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 200 MPa were used.

  The conductive adhesive film according to Example 11 has a Tg after curing of 150 ° C. and a thermoplastic component of 40 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 200 MPa were used.

  The conductive adhesive film according to Example 12 has, as a binder resin, a Tg after curing of 150 ° C. and 55 wt% of a thermoplastic component, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 200 MPa were used.

  The conductive adhesive film according to Example 13 has a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, gold / nickel-coated resin particles having a 10% compressive strength of 30 MPa were used as the conductive particles.

  The conductive adhesive film according to Example 14 has a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 50 MPa were used.

  The conductive adhesive film according to Example 15 has a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and after curing. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 400 MPa were used.

  The conductive adhesive film according to Example 16 has, as a binder resin, a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt%, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and after curing. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 500 MPa were used.

  The conductive adhesive film according to Comparative Example 1 has a Tg after curing of 130 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and after curing. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, as the conductive particles, gold / nickel-coated resin particles having a 10% compressive strength of 200 MPa were used.

[Examples and comparative examples of metal particles]
The conductive adhesive film according to Example 17 has a Tg after curing of 140 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.1 were used as the conductive particles.

  The conductive adhesive film according to Example 18 has a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.1 were used as the conductive particles.

  The conductive adhesive film according to Example 19 has a Tg after curing of 180 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and after curing. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.1 were used as the conductive particles.

  The conductive adhesive film according to Example 20 has a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.0 GPa, and after curing. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.1 were used as the conductive particles.

  The conductive adhesive film according to Example 21 has, as a binder resin, a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt%, a 30 ° C. elastic modulus (E ′) after curing of 1.3 GPa, and after curing. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.1 were used as the conductive particles.

  The conductive adhesive film according to Example 22 has a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 2.0 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.1 were used as the conductive particles.

  The conductive adhesive film according to Example 23 has a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 0.5 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.1 were used as the conductive particles.

  The conductive adhesive film according to Example 24 has, as a binder resin, a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt%, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and after curing. A 125 ° C. elastic modulus (E ′) having 0.8 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.1 were used as the conductive particles.

  The conductive adhesive film according to Example 25 has a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 1.0 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.1 were used as the conductive particles.

  The conductive adhesive film according to Example 26 has a Tg after curing of 150 ° C. and a thermoplastic component of 35 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.1 were used as the conductive particles.

  The conductive adhesive film according to Example 27 has a Tg after curing of 150 ° C. and a thermoplastic component of 40 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.1 were used as the conductive particles.

  The conductive adhesive film according to Example 28 has a Tg after curing of 150 ° C. and a thermoplastic component of 55 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.1 were used as the conductive particles.

  The conductive adhesive film according to Example 29 has a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.04 were used as the conductive particles.

  The conductive adhesive film according to Example 30 has a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt% as a binder resin, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.075 were used as the conductive particles.

  The conductive adhesive film according to Example 31 has, as a binder resin, a Tg after curing of 150 ° C. and a thermoplastic component of 50 wt%, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and after curing. The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.125 were used as the conductive particles.

  The conductive adhesive film according to Comparative Example 2 has, as a binder resin, a Tg after curing of 130 ° C., a thermoplastic component of 50 wt%, a 30 ° C. elastic modulus (E ′) after curing of 1.5 GPa, and a cured resin The one with 125 ° C. elastic modulus (E ′) of 0.6 GPa was used. Further, nickel particles having a bulk specific gravity / true specific gravity of 0.1 were used as the conductive particles.

  The 10% compressive strength of the resin core metal-plated particles is determined by using a micro compression tester (MCTM-200, manufactured by Shimadzu Corporation) at room temperature, a test load of 3.00 (gf), and a load speed constant of 2 (0.135 gf / sec), a displacement scale of 5.00 (μm), and an indenter 50 (μmφ). Moreover, the bulk specific gravity of the nickel particles was measured with a Scott volume meter (ASTM-B-329-98, manufactured by Tsutsui Riken Kikai Co., Ltd.).

  As shown in Table 1, in the conductive adhesive films according to Examples 1 to 31, since a binder resin having a Tg after curing of 140 ° C. or higher is used, even after the temperature cycle test, the resistance value The rate of increase can be kept low. On the other hand, in Comparative Examples 1 and 2, since the binder resin having a Tg of 130 ° C. after curing is used, the rate of increase in the resistance value after the temperature cycle test is high. Therefore, it can be seen that by using the conductive adhesive film according to the example, good conduction reliability can be maintained even in an actual use environment where the temperature difference is large.

  When Example 1 is compared with Examples 2 and 3, the conductive adhesive film according to Example 1 uses a binder resin whose Tg after curing is 140 ° C., and in Example 2, the same 150 ° C., In Example 3, the same one at 180 ° C. is used. Since the increase rate of the resistance value after the temperature cycle test is better in Examples 2 and 3, it can be seen that the binder resin having a Tg of 150 ° C. to 180 ° C. after curing is preferable.

  Similarly, when Example 17 and Examples 18 and 19 are compared, the rate of increase in resistance value after the temperature cycle test is better in Examples 18 and 19, so that as a binder resin, It can be seen that a Tg of 150 ° C. to 180 ° C. is preferable.

  When Example 4 is compared with Examples 5 and 6, the conductive adhesive film according to Example 4 uses a binder resin having a 30 ° C. elastic modulus (E ′) of 1.0 GPa. In Example 6, 1.3 GPa is used, and in Example 6, the same 2.0 GPa is used. Since the rate of increase in resistance after the temperature cycle test is better in Examples 5 and 6, the binder resin preferably has a 30 ° C. elastic modulus (E ′) of 1.3 to 2.0 GPa. I understand.

  Similarly, when Example 20 and Examples 21 and 22 are compared, the rate of increase in resistance value after the temperature cycle test is better in Examples 21 and 22, and as a binder resin, the elasticity at 30 ° C. It can be seen that the rate (E ′) is preferably 1.3 to 2.0 GPa.

  When Example 7 is compared with Examples 8 and 9, in the conductive adhesive film according to Example 7, a binder resin having a 125 ° C. elastic modulus (E ′) of 0.5 GPa is used. 0.8 GPa and 1.0 GPa in Example 9 are used. Since the rate of increase in resistance after the temperature cycle test is better in Examples 8 and 9, the binder resin preferably has a 125 ° C. elastic modulus (E ′) of 0.8 to 1.0 GPa. I understand.

  Similarly, when Example 23 is compared with Examples 24 and 25, the rate of increase in the resistance value after the temperature cycle test is better in Examples 24 and 25. It can be seen that (E ′) is preferably 0.8 to 1.0 GPa.

  When Example 10 is compared with Examples 11 and 12, the conductive adhesive film according to Example 10 contains 35 wt% of a thermoplastic component as a binder resin, whereas Example 11 shows the same. 40 wt%, and in Example 12, the same 55 wt% is used. Since connection intensity | strength is more favorable in Examples 11 and 12, it turns out that what contains 40 wt%-55 wt% of thermoplastic components as binder resin is preferable.

  Similarly, when Example 26 is compared with Examples 27 and 28, since the connection strength is better in Examples 27 and 28, the binder component contains 40 wt% to 55 wt% of a thermoplastic component. It turns out that a thing is preferable.

  When Example 13 is compared with Example 14, the conductive particles according to Example 13 have a 10% compressive strength of 30 MPa, whereas Example 14 has the same 50 MPa. And since the initial conduction resistance is good in Example 14, it is understood that the 10% compressive strength is preferably 50 MPa or more when the resin core metal plating particles are used as the conductive particles.

  Further, when Example 15 is compared with Example 16, the conductive particles according to Example 15 have a 10% compressive strength of 400 MPa, whereas Example 16 has the same 500 MPa. And since the rate of increase in resistance value after the temperature cycle test is good in Example 15, when using resin core metal plating particles as conductive particles, it is preferable that the 10% compressive strength is 400 MPa or less. I understand.

  Further, when Example 29 is compared with Examples 30 and 31, the conductive particles according to Example 29 have a bulk specific gravity / true specific gravity of 0.04, whereas Example 30 has the same. 075 and Example 31 are 0.125. The rate of increase in resistance after the temperature cycle test is good in Examples 30 and 31, so that when using metal particles as conductive particles, the bulk specific gravity / true specific gravity is 0.05 or more and 0.15 or less. It turns out that it is preferable.

DESCRIPTION OF SYMBOLS 1 Solar cell module, 2 photovoltaic cell, 3 tab wire, 4 strings, 5 matrix, 6 sheet, 7 surface cover, 8 back sheet, 9 metal frame, 12 finger electrode, 13 back surface electrode, 14 tab wire connection part, 17 Conductive adhesive film, 22 binder resin, 23 conductive particles, 24 release substrate, 25 reel, 30 connector for evaluation, 31 glass substrate, 32 tab wire, 33 conductive adhesive film, 34 EVA, 35 PET film

Claims (7)

In the conductive adhesive for connecting the electrode formed on the solar battery cell and the tab wire connecting the plurality of solar battery cells,
Containing at least a curable resin, conductive particles, and a curing agent,
The conductive particles are seen including a resin core metal plated particles,
The resin core metal plating particles have a 10% compressive strength of 30 to 500 MPa,
A conductive adhesive having a Tg after curing of 140 ° C. or higher. In the conductive adhesive for connecting the electrode formed on the solar battery cell and the tab wire connecting the plurality of solar battery cells,
Containing at least a curable resin, conductive particles, and a curing agent,
The conductive particles include metal particles,
The bulk specific gravity / true specific gravity of the metal particles is 0.15 or less,
A conductive adhesive having a Tg after curing of 140 ° C. or higher. In the conductive adhesive for connecting the electrode formed on the solar battery cell and the tab wire connecting the plurality of solar battery cells,
Containing at least a curable resin, conductive particles, and a curing agent,
The conductive particles include resin core metal plating particles, or metal particles,
The 30 ° C. elastic modulus (E ′) after curing of the conductive adhesive is 1.3 to 1.8 GPa, and
125 ° C. elastic modulus (E ′) after curing of the conductive adhesive is 0.5 GPa or more,
A conductive adhesive having a Tg after curing of 140 ° C. or higher. In the conductive adhesive for connecting the electrode formed on the solar battery cell and the tab wire connecting the plurality of solar battery cells,
Containing at least a curable resin, conductive particles, and a curing agent,
The conductive particles include resin core metal plating particles, or metal particles,
The thermoplastic component in the conductive adhesive is 35 to 55 wt%,
A conductive adhesive having a Tg after curing of 140 ° C. or higher. Tg after hardening of the said conductive adhesive is 150-180 degreeC, The conductive adhesive of any one of Claims 1-4. Solar cells,
A tab wire connecting the plurality of solar cells,
A conductive adhesive layer provided between the electrode formed in the solar battery cell and the tab wire;
The conductive adhesive layer is a cured product of the conductive adhesive according to any one of claims 1 to 5.
Is a solar cell module. A step of juxtaposing a plurality of solar cells on which electrodes are formed;
A step of temporarily arranging tab wires connecting the plurality of solar cells to the electrodes of the solar cells via a conductive adhesive;
Curing the conductive adhesive by heating and pressing the tab wire, connecting the electrode and the tab wire, and connecting the adjacent solar cells through the tab wire;
The said conductive adhesive is a conductive adhesive in any one of Claims 1-5.
A method for manufacturing a solar cell module.

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