JP2019024097A - Conductive adhesive film and solar battery module - Google Patents

Abstract

To provide a conductive adhesive film by which a surface electrode of a photovoltaic cell can be connected to a wiring member without exerting an adverse effect on the photovoltaic cell, and satisfactory connection reliability can be achieved.SOLUTION: Provided is a conductive adhesive film for electrically connecting a surface electrode of a photovoltaic cell with a wiring member, comprising an insulative adhesive 2 and conductive particles 1. Supposing that the conductive particles 1 have an average particle diameter of r (μm), and the conductive adhesive film has a thickness of t (μm), a value (t/r) falls within a range of 0.75-17.5. A content of the conductive particles 1 is 1.7-15.6 vol.% based on a total volume of the conductive adhesive film.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive adhesive film and a solar cell module.

  The solar cell module has a structure in which a plurality of solar cells are connected in series and / or in parallel via a wiring member electrically connected to the surface electrode. In producing this solar cell module, solder has been conventionally used to connect the surface electrode of the solar cell and the wiring member (see, for example, Patent Documents 1 and 2). Solder is widely used because it is excellent in connection reliability such as electrical conductivity and fixing strength, is inexpensive and versatile.

  Moreover, as a wiring connection method that does not use solder, a connection method using a conductive adhesive or a connection method using a conductive film is known (see, for example, Patent Documents 3 to 6).

JP 2004-204256 A JP-A-2005-050780 JP 2000-286436 A JP 2001-357897 A Japanese Patent No. 3448924 JP 2005-101519 A

  However, when connecting the surface electrode of the photovoltaic cell and the wiring member using solder, the melting temperature of the solder is usually about 230 to 260 ° C. It may adversely affect the semiconductor structure of the solar battery cell and cause deterioration of the characteristics of the solar battery cell.

  Further, in solder connection, it is difficult to control the thickness of the connection interface with the adherend due to the characteristics of the solder, and it is difficult to obtain sufficient dimensional accuracy when packaged. If sufficient dimensional accuracy cannot be obtained, it will lead to a decrease in product yield during the packaging process.

  In addition, as described in Patent Documents 3 to 5, even when the connection between the surface electrode of the solar battery cell and the wiring member is performed using a conductive adhesive, sufficient connection reliability is not always obtained, and the high temperature The characteristics may deteriorate significantly over time under high humidity conditions.

  Furthermore, as described in the above-mentioned Patent Document 6, in the case where the surface electrode of the solar battery cell and the wiring member are connected using the conductive film, since it can be bonded at a low temperature, the soldering is used. Although the bad influence to the photovoltaic cell which arises can be suppressed, the influence of the surface state of a to-be-adhered body is not considered, and connection reliability was not necessarily enough.

  The present invention has been made in view of the above-described problems of the prior art, and is used when connecting solar cells such as single crystal, polycrystalline or amorphous silicon wafers and compound semiconductor wafers via a wiring member. A conductive adhesive film capable of connecting the surface electrode of the solar battery cell and the wiring member without adversely affecting the solar battery cell and obtaining sufficient connection reliability; and It aims at providing the used solar cell module.

  In order to achieve the above object, the present invention is a conductive adhesive film for electrically connecting a surface electrode of a solar battery cell and a wiring member, and contains an insulating adhesive and conductive particles. When the average particle diameter of the conductive particles is r (μm) and the thickness of the conductive adhesive film is t (μm), the value of (t / r) is in the range of 0.75 to 17.5. And providing a conductive adhesive film in which the content of the conductive particles is 1.7 to 15.6% by volume based on the total volume of the conductive adhesive film.

  According to the conductive adhesive film of the present invention having the above configuration, the surface electrode of the solar battery cell and the wiring member can be connected without adversely affecting the solar battery cell, and sufficient connection reliability is obtained. It is possible.

  In the conductive adhesive film of the present invention, the insulating adhesive preferably contains 9 to 34% by mass of a rubber component based on the total amount of the insulating adhesive.

  Moreover, it is preferable that the elasticity modulus of the electroconductive adhesive film of this invention is 0.5-4.0GPa.

  Furthermore, in the conductive adhesive film of the present invention, the shape of the conductive particles is preferably a chestnut shape or a spherical shape.

  The present invention is also a solar cell module having a structure in which a plurality of solar cells having a surface electrode are connected via a wiring member electrically connected to the surface electrode, the surface electrode and the wiring Provided is a solar cell module in which members are connected by the conductive adhesive film of the present invention.

  In such a solar cell module, since the surface electrode of the solar cell and the wiring member are connected using the conductive adhesive film of the present invention described above, there is no adverse effect on the solar cell and sufficient connection is achieved. Reliability can be obtained.

  According to the present invention, a conductive adhesive film that can connect the surface electrode of the solar battery cell and the wiring member without adversely affecting the solar battery cell, and can obtain sufficient connection reliability, And the solar cell module using the same can be provided.

It is a schematic cross section which shows one Embodiment of the electroconductive adhesive film of this invention. It is explanatory drawing for demonstrating the connection state of to-be-adhered bodies at the time of using the conductive adhesive film from which the value of (t / r) differs. It is a schematic diagram which shows the principal part of the solar cell module of this invention. The ratio (film thickness t / particle diameter r) between the film thickness t of the conductive adhesive film and the average particle diameter r of the conductive particles and the fill factor (FF) after 500 hours in an atmosphere of 85 ° C. and 85% RH. .) Change amount {F. F. (500h) / F. F. It is a graph which shows the relationship with (0h)}.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic cross-sectional view showing an embodiment of the conductive adhesive film of the present invention. As shown in FIG. 1, the conductive adhesive film 10 of the present invention contains at least conductive particles 1 and an insulating adhesive 2.

  The conductive adhesive film 10 of the present invention is for connecting an electrode of a solar battery cell and a wiring wire (wiring member) for connecting the solar battery cell in series and / or in parallel. An electrode (surface electrode) for taking out electricity is formed on the front and back surfaces of the solar battery cell.

  Here, examples of the surface electrode include known materials that can obtain electrical continuity, such as a general silver-containing glass paste or a silver paste in which various conductive particles are dispersed in an adhesive resin. Gold paste, carbon paste, nickel paste, aluminum paste, and ITO formed by firing or vapor deposition. Among these, a glass paste electrode containing silver is preferably used from the viewpoints of heat resistance, conductivity, stability, and cost.

  In the case of a solar battery cell, an Ag electrode and an Al electrode are mainly provided as surface electrodes on a substrate made of at least one of Si single crystal, polycrystal, and amorphous by screen printing or the like.

  At this time, the electrode surface may generally have unevenness with a surface roughness (ten-point average surface roughness Rz) of 3 to 30 μm. In particular, an electrode formed in a solar battery cell often has a rough surface roughness Rz of 8 to 18 μm. As a result of intensive studies, the present inventors have found that the connection reliability is deteriorated in conventional conductive adhesive compositions and conductive films due to these irregularities.

  That is, in the case of an electrode surface having such a concavo-convex shape, if the particle diameter of the conductive particles is small and the blending amount is not appropriate, the particles are buried in the recesses on the electrode surface, and sufficient conductivity cannot be obtained. In addition, when the thickness of the coating film formed using the conductive adhesive composition or conductive film is smaller than the uneven height difference of the electrode surface, sufficient adhesion with the adherend cannot be obtained and the connection reliability Sex is reduced.

  Moreover, when the thickness of the coating film formed with respect to the particle diameter of electroconductive particle is too large, the resin of the surface of electroconductive particle is not fully excluded at the time of thermocompression bonding, but electroconductivity falls. Further, the ratio of the average particle diameter r (μm) of the conductive particles to the thickness t (μm) of the coating film to be formed (coating film thickness t / average particle diameter r of the conductive particles) is less than 0.75. In this case, the adhesive component is not sufficiently filled, and there is a high possibility of causing a connection failure.

  Here, in order to obtain sufficient connection reliability between the adherends, the conductive particles dispersed in the insulating adhesive component between the conductive adhesive film and the unevenness of the electrode surface. It was found that the ratio of the particle size (average particle size) of the film to the thickness of the coating film formed (thickness of the conductive adhesive film) is greatly related.

  In addition, the thickness of the electroconductive adhesive film prescribed | regulated by this invention can be measured with a micrometer. The average particle diameter of the conductive particles is determined by observing the conductive particles using a scanning electron microscope (SEM), measuring 20 particle diameters when the particle size is 3,000 times, and measuring the average particle diameter. Diameter can be employed.

  The conductive adhesive film 10 of the present invention has a ratio (film thickness t / average) of the average particle diameter r (μm) of the conductive particles in the conductive adhesive film 10 and the thickness t (μm) of the conductive adhesive film 10. The particle diameter r) is 0.75 to 17.5, and the content of the conductive particles 1 in the conductive adhesive film 10 is 1.7 to 15.5 based on the total volume of the conductive adhesive film 10. It must be 6% by volume.

  The ratio (t / r) between the average particle diameter r of the conductive particles 1 and the thickness t of the conductive adhesive film 10 is 0.75 to 17.5, and the blending amount of the conductive particles 1 is conductive adhesive. If the total volume of the film 10 is 1.7 to 15.6% by volume, even when one particle of the conductive particles is buried in the concave portion on the surface of the adherend, conductivity between the particles can be obtained. A sufficient electrical connection between the attachments can be ensured.

  FIG. 2 is an explanatory diagram for explaining a case where adherends are connected to each other using a conductive adhesive film. 2 (a) to 2 (d) show connection states when conductive adhesive films having different values of the above (t / r) are used. In FIG. 2 (a), (t / r) When the conductive adhesive film 20 having a value of 1 to 17.5 is used, the conductive adhesive film 30 having a value of (t / r) of 0.75 or more and less than 1 in FIG. 2C, when the conductive adhesive film 40 having a value of (t / r) less than 0.75 is used, the value of (t / r) exceeds 17.5 in FIG. 2D. When the electroconductive adhesive film 50 is used, each is shown. Moreover, as the adherend, the surface electrode 3 of the solar battery cell and the wiring member 4 for connecting the solar battery cells are used, and the surface electrode 3 has irregularities on the surface. And FIG. 2 has shown the case where a conductive adhesive film is arrange | positioned between these adherends and it connects by thermocompression bonding.

  When the conductive adhesive film 20 shown in FIG. 2A is used, the unevenness of the surface electrode 3 can be sufficiently embedded with the conductive particles 1, and adhesion between the surface electrode 3 and the wiring member 4 and electrical The connection can be fully achieved. In addition, when the conductive adhesive film 30 shown in FIG. 2B is used, the conductive particles 1 are deformed and embedded in the surface electrode, and the unevenness of the surface electrode 3 is sufficiently embedded with the conductive particles 1. Thus, adhesion and electrical connection between the surface electrode 3 and the wiring member 4 can be sufficiently achieved.

  On the other hand, when the conductive adhesive film 40 shown in FIG. 2 (c) is used, the average particle diameter of the conductive particles 1 is too large with respect to the thickness of the film. Even if the electrode is buried, the insulating adhesive 2 and the wiring member 4 are not in contact with each other, and cannot be bonded. Furthermore, when the conductive adhesive film 50 shown in FIG. 2D is used, the average particle diameter of the conductive particles 1 is too small with respect to the thickness of the film. They are buried in the recesses, and these electrical connections cannot be ensured.

  Thus, the favorable connection between adherends is securable because the value of (t / r) in a conductive adhesive film exists in the range of 0.75-17.5. Further, from the viewpoint of improving the connection between adherends, the value of (t / r) is preferably 1.0 to 12.0, and preferably 2.0 to 9.0. Is more preferable.

  The conductive adhesive film 10 of the present invention includes at least an insulating adhesive component 2 and conductive particles 1. Although there is no restriction | limiting in particular as this insulating adhesive component 2, It is preferable to use a thermosetting resin from a viewpoint of connection reliability.

  Known thermosetting resins can be used, for example, epoxy resins, phenoxy resins, acrylic resins, polyimide resins, polyamide resins, polycarbonate resins, etc. Among them, the viewpoint of obtaining more sufficient connection reliability Therefore, it is preferable to include at least one of an epoxy resin, a phenoxy resin, and an acrylic resin.

  Moreover, it is preferable that the electroconductive adhesive film 10 contains a rubber component as the insulating adhesive component 2 from a viewpoint of the fluidity | liquidity of resin and the physical property control of a film. As the rubber component, known materials can be used. Examples thereof include acrylic rubber, butyl rubber, silicone rubber, urethane rubber, and fluororubber, and are miscible with thermosetting resin and adherence to an adherend. In view of the above, acrylic rubber is preferable.

  The blending amount of the rubber component is preferably 9 to 34% by mass based on the total amount of the insulating adhesive component 2. When the blending amount of the rubber component is 9 to 34% by mass based on the total amount of the insulating adhesive component 2, the adhesiveness between the conductive adhesive film 10 and the adherend is excellent, and the adherend due to environmental changes The followability is also good for physical fluctuations, and poor connection between adherends can be sufficiently suppressed.

  Although there is no restriction | limiting in particular as the electroconductive particle 1, For example, a gold particle, a silver particle, a copper particle, a nickel particle, a gold plating particle, a copper plating particle, a nickel plating particle etc. are mentioned. Moreover, the electroconductive particle 1 is made into the shape of a chestnut shape or a spherical particle | grain shape from a viewpoint which fully embeds the surface unevenness | corrugation of a to-be-adhered body at the time of a connection, and ensures sufficient electrical connection between to-be-adhered bodies. It is preferable. That is, if the shape of the conductive particles 1 is a chestnut shape or a spherical shape, the unevenness can be sufficiently embedded even in a complicated uneven shape on the surface of the adherend, and vibration or expansion after connection can be achieved. Since the followability of the electroconductive particle 1 becomes high with respect to the fluctuation | variation of this, it is preferable.

  The average particle size r of the conductive particles 1 is not particularly limited as long as the value of (t / r) is within the range of 0.75 to 17.5, but is preferably 2 to 30 μm. 10 to 20 μm is more preferable. In particular, when the surface roughness Rz of the adherends is in the range of 3 to 30 μm (more preferably 8 to 18 μm), the average particle diameter of the conductive particles 1 is within the above range. The adhesiveness and electrical conductivity of can be made better. The average particle diameter r of the conductive particles 1 is preferably ½ Rz or more, more than Rz, with respect to the surface roughness (ten-point average surface roughness Rz, maximum height Ry) of the adherend. It is more preferable that it is Ry or more.

  Moreover, although content of the electroconductive particle 1 in the electroconductive adhesive film 10 needs to be 1.7-15.6 volume% on the basis of the whole volume of the electroconductive adhesive film 10, it adheres From the viewpoint of improving the adhesiveness and electrical conductivity between each other, the content is preferably 2 to 12% by volume, and more preferably 3 to 8% by volume. In addition, the electroconductive adhesive film 10 can show anisotropic conductivity because content of the electroconductive particle 1 is 1.7-15.6 volume%.

  In the conductive adhesive film 10 of the present invention, in addition to the above components, a silane coupling agent, a titanate coupling agent, Contains modifying materials such as aluminate coupling agents, dispersing agents such as calcium phosphate and calcium carbonate, and chelating materials for suppressing silver and copper migration, etc., in order to improve the dispersibility of conductive particles Can be made.

  The conductive adhesive film 10 of the present invention is superior to the paste-like conductive adhesive composition in terms of film thickness dimensional accuracy and pressure distribution during pressure bonding. Such a conductive adhesive film 10 can be produced, for example, by applying a coating solution obtained by dissolving or dispersing the above-described various materials in a solvent onto a release film such as a polyethylene terephthalate film and removing the solvent. The film thickness of the conductive adhesive film 10 can be controlled by adjusting the non-volatile content in the coating solution and adjusting the gap of the applicator or lip coater.

  The elastic modulus of the conductive adhesive film 10 is preferably 0.5 to 4.0 GPa. When the elastic modulus is less than 0.5 GPa, the film strength tends to be weak and the adhesive force tends to decrease, and when it exceeds 4.0 GPa, the film becomes hard and the stress relaxation property between adherends tends to be poor.

  The thickness t of the conductive adhesive film 10 is not particularly limited as long as the value of (t / r) falls within the range of 0.75 to 17.5, but is preferably 5 to 50 μm. 10 to 35 μm is more preferable. In particular, when the surface roughness Rz of the adherends is within a range of 3 to 30 μm (more preferably 8 to 18 μm), the thickness of the conductive adhesive film 10 is within the above range, so The adhesiveness and electrical conductivity of can be made better. Further, the thickness t of the conductive adhesive film 10 is preferably Rz or more with respect to the surface roughness (ten-point average surface roughness Rz, maximum height Ry) of the adherend, and is Ry or more. More preferably.

  The conductive adhesive film 10 of the present invention can be most suitably used for solar cells. A solar cell includes a plurality of solar cells connected in series and / or in parallel, sandwiched with tempered glass or the like for environmental resistance, and provided with external terminals whose gaps are filled with a transparent resin. Used as a module. The conductive adhesive film 10 of the present invention is suitably used for applications in which a wiring member for connecting a plurality of solar cells in series and / or in parallel and a surface electrode of the solar cells.

  The solar cell module of the present invention has a structure in which a plurality of solar cells having a surface electrode as described above are connected via a wiring member electrically connected to the surface electrode, The surface electrode and the wiring member are connected by the conductive adhesive film of the present invention.

  Here, FIG. 3 is a schematic diagram showing a main part of the solar cell module of the present invention, and shows an outline of a structure in which a plurality of solar cells are connected to each other by wiring. 3A shows the front side of the solar cell module, FIG. 3B shows the back side, and FIG. 3C shows the side.

  As shown in FIGS. 3A to 3C, the solar cell module 100 includes a grid electrode 7 and a bus electrode (front electrode) 3a on the front side of the semiconductor wafer 6, and a back electrode 8 and a bus electrode (front electrode) on the back side. A plurality of solar cells each having a surface electrode 3 b are connected to each other by a wiring member 4. The wiring member 4 has one end connected to the bus electrode 3a as the surface electrode and the other end connected to the bus electrode 3b as the surface electrode via the conductive adhesive film 10 of the present invention.

  In the solar cell module 100 having such a configuration, the surface electrode and the wiring member are connected by the above-described conductive adhesive film of the present invention, so that there is no adverse effect on the solar cells and sufficient connection reliability is achieved. Can be obtained.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

<Measurement method of each physical property>
(1) Film thickness of conductive adhesive film: Measured with a micrometer (manufactured by Mitutoyo Corp, ID-C112). In addition, when t / r was less than 1, the film thickness of the part in which electroconductive particle does not exist was measured using the focal depth meter.

(2) Surface roughness (10-point average surface roughness Rz, maximum height Ry) of the adherend: Observation using an ultra-deep shape measuring microscope (manufactured by KEYENCE, VK-8510), image measurement / analysis Calculation was performed using software (manufactured by KEYENCE, VK-H1A7). The ten-point average surface roughness Rz and the maximum height Ry were described in accordance with JIS B0601-1994.

(3) Elastic modulus of conductive adhesive film: A conductive adhesive composition was applied on a polyethylene terephthalate film whose surface was treated with silicone using an applicator (manufactured by YOSHIMISU), and then 170 ° C for 20 minutes in an oven. It dried on the conditions of. Thereafter, the polyethylene terephthalate film was peeled off to obtain a conductive adhesive film having a thickness of 35 μm. The obtained conductive adhesive film was cut into a strip shape having a width of 5 mm and a length of 35 mm, and the elastic modulus at 25 ° C. was measured with a dynamic viscoelasticity measuring device (Rheometric Scientific, SOLIDS ANALYZER, distance between chucks: 2 cm). .

(4) Peel strength measurement (MPa): After producing a solar cell with a tab wire, the end of the tab wire is bent vertically and fixed to a chuck of a peel strength measuring device (ORIENTEC, STA-1150) The peel strength was measured by pulling up at a pulling speed of 2 cm / s. At this time, if the wafer is cracked before the tab wire is peeled off, it can be said that it has sufficient peel strength.

(5) Wafer warpage (%): A solar cell with a tab line is placed on a smooth surface so that the convex side (opposite side of the tab line attaching surface) is in contact with the smooth surface, and one end (tab line) (End part with respect to the longitudinal direction) was fixed on a smooth surface, and the floating of the opposite end part from the smooth surface was measured at five points with a depth of focus meter to calculate an average value. The ratio of the average value of the float to the length of one side of the solar battery cell was determined as the amount of warpage (%) of the wafer.

(6) F.R. F. (500h) / F. F. (0h): For a solar cell with a tab line, an IV curve was measured using a solar simulator (WXS-155S-10, AM1.5G) manufactured by Wacom Denso Co., Ltd. F. (Curve factor) and F. after 500 hours in an atmosphere of 85 ° C. and 85% RH. F. And asked. And after 500 hours, F.I. F. To early F. F. Is the value obtained by dividing F. F. (500h) / F. F. Calculated as (0h). the value of t / r; F. (500h) / F. F. The relationship with the value of (0h) is shown in the graph of FIG. Note that in FIG. F. (500h) / F. F. When the value of (0h) is 0.98 or less, it can be determined that the connection reliability is insufficient.

(7) Cell yield: In 10 solar cells, the cell state after attaching the tab line was observed, and the ratio (%) excluding those with cracks or peeling was determined as the yield.

(Examples 1-1 to 1-3)
First, an acrylic rubber obtained by copolymerizing 40 parts by mass of butyl acrylate, 30 parts by mass of ethyl acrylate, 30 parts by mass of acrylonitrile, and 3 parts by mass of glycidyl methacrylate (product name: KS8200H, manufactured by Hitachi Chemical Co., Ltd., molecular weight: 850,000) were prepared. 125 g of this acrylic rubber and 50 g of phenoxy resin (product name: PKHC, manufactured by Union Carbide, weight average molecular weight 45,000) were dissolved in 400 g of ethyl acetate to obtain a 30% solution. Next, 325 g of a liquid epoxy containing a microcapsule type latent curing agent (product name: NovaCure HX-3941HP, manufactured by Asahi Kasei Chemicals, epoxy equivalent 185) was added to the above solution and stirred to obtain an adhesive composition. . In addition, Table 1 shows the blending amount of each material in the adhesive composition.

  Conductive particles having an average particle diameter of 2 μm (conductive particles formed by forming a Ni and Au layer with a thickness of 0.1 μm on the surface of a polystyrene core having a diameter of 1.8 μm) for this adhesive composition , Spherical, specific gravity 2.8) was dispersed to obtain a conductive adhesive composition. At this time, the conductive particles were blended so that the content would be 5% by volume based on the total solid content of the conductive adhesive composition. A conductive adhesive composition was obtained. The average particle size of the conductive particles is determined by observing the conductive particles with a SEM (device name: S-510, manufactured by Hitachi, Ltd.) at a magnification of 3000 times, and the particle size of any 20 conductive particles. Measured and calculated as the average value. Moreover, the compounding quantity of electroconductive particle was computed from particle | grain specific gravity.

  The obtained conductive adhesive composition was applied onto a polyethylene terephthalate film using an applicator (manufactured by YOSHIMISU), dried on a hot plate at 70 ° C. for 3 minutes, and a film thickness of 15 μm (Example 1-1). ), 25 μm (Example 1-2) and 35 μm (Example 1-3), respectively. The film thickness was adjusted by changing the gap of the applicator. At this time, the gap was adjusted from the relational expression between the gap and the film thickness after drying so that a desired film thickness was obtained.

  Electrode wiring (material: silver glass paste, 2 mm × 12.5 cm, Rz = 10 μm, Ry = 14 μm) formed on the solar cell (125 mm × 125 mm, thickness 310 μm) with the obtained conductive adhesive film (2 mm width), and arranged between a TAB wire (manufactured by Hitachi Cable Ltd., A-TPS) as a wiring member and the surface electrode of the solar battery cell. Next, using a crimping tool (device name: AC-S300, manufactured by Nikka Equipment Engineering Co., Ltd.), adhesion was performed under the conditions of 170 ° C., 2 MPa, 20 seconds, and as shown in FIG. The surface side electrode wiring (surface electrode) and the TAB line (wiring member) were connected via a conductive adhesive film. About the obtained photovoltaic cell with a tab wire, confirmation of appearance (presence or absence of cell crack or tab wire peeling), peel strength, and F. of the solar cell. F. (500h) / F. F. (0h) was measured. Here, the appearance was visually observed, and the case where there was no cell cracking or peeling of the tab line was evaluated as A, and the case where a part of the cell was cracked was evaluated as B. The evaluation results are shown in Tables 2 and 3.

(Examples 2-1 to 2-3)
As the conductive particles, conductive particles having an average particle diameter of 5 μm (conductive particles formed by forming Ni and Au layers with a thickness of 0.1 μm on the surface of a polystyrene core having a diameter of 4.8 μm, spherical, Except for using specific gravity 2.8), the same materials as in Examples 1-1 to 1-3 were used, and the same operations as in Examples 1-1 to 1-3 were performed. Evaluation similar to -3 was performed. The evaluation results are shown in Tables 2 and 3.

(Examples 3-1 to 3-3)
As conductive particles, conductive particles having an average particle diameter of 10 μm (conductive particles formed by forming Ni and Au layers with a thickness of 0.1 μm on the surface of a polystyrene core having a diameter of 9.8 μm, spherical, Except for using specific gravity 2.8), the same materials as in Examples 1-1 to 1-3 were used, and the same operations as in Examples 1-1 to 1-3 were performed. Evaluation similar to -3 was performed. The evaluation results are shown in Tables 2 and 3.

(Examples 4-1 to 4-3)
As the conductive particles, conductive particles having an average particle diameter of 20 μm (conductive particles formed by forming Ni and Au layers with a thickness of 0.1 μm on the surface of a polystyrene core having a diameter of 19.8 μm, spherical, Except for using specific gravity 2.8), the same materials as in Examples 1-1 to 1-3 were used, and the same operations as in Examples 1-1 to 1-3 were performed. Evaluation similar to -3 was performed. The evaluation results are shown in Tables 2 and 3.

(Examples 5-1 to 5-3)
As the conductive particles, the same materials as in Examples 1-1 to 1-3 were used except that conductive particles having an average particle diameter of 12 μm (nickel particles, chestnut shape, specific gravity 3.36) were used. The same work as 1-1 to 1-3 was performed, and the same evaluation as in Examples 1-1 to 1-3 was performed. The evaluation results are shown in Tables 2 and 3.

(Examples 6-1 to 6-3)
As the conductive particles, conductive particles having an average particle diameter of 8 μm (conductive particles formed by forming Ni and Au layers with a thickness of 0.1 μm on the surface of a polystyrene core having a diameter of 7.8 μm, spherical, Except for the specific gravity 8.6), the same materials as in Examples 1-1 to 1-3 were used, and the same operations as in Examples 1-1 to 1-3 were performed. Evaluation similar to -3 was performed. The evaluation results are shown in Tables 2 and 3.

(Comparative Example 1)
A TAB wire (A-TPS, manufactured by Hitachi Cable, Ltd.) and a solar battery cell were soldered by heating and melting the TAB wire with a lamp heater. About the obtained photovoltaic cell with a tab wire, evaluation similar to Examples 1-1 to 1-3 was performed. The evaluation results are shown in Tables 2 and 3.

DESCRIPTION OF SYMBOLS 1 ... Conductive particle, 2 ... Insulating adhesive, 3 ... Surface electrode, 3a ... Bus electrode (surface electrode), 3b ... Bus electrode (surface electrode), 4 ... Wiring member, 6 ... Semiconductor wafer, 7 ... Grid electrode , 8 ... back electrode, 10 ... conductive adhesive film, 100 ... solar cell module.

Claims (5)

A conductive adhesive film for electrically connecting a surface electrode of a solar battery cell and a wiring member,
Containing an insulating adhesive and conductive particles;
The average particle diameter of the conductive particles is r (μm), the thickness of the conductive adhesive film is t (μm), and the value of (t / r) is in the range of 0.75 to 17.5,
The electroconductive adhesive film whose content of the said electroconductive particle is 1.7-15.6 volume% on the basis of the whole volume of the said electroconductive adhesive film.   The conductive adhesive film according to claim 1, wherein the insulating adhesive contains 9 to 34% by mass of a rubber component based on the total amount of the insulating adhesive.   The electroconductive adhesive film of Claim 1 or 2 whose elasticity modulus is 0.5-4.0GPa.   The conductive adhesive film according to any one of claims 1 to 3, wherein the conductive particles have a chestnut shape or a spherical shape. A solar cell module having a structure in which a plurality of solar cells having a surface electrode are connected via a wiring member electrically connected to the surface electrode,
The solar cell module in which the said surface electrode and the said wiring member are connected by the electroconductive adhesive film as described in any one of Claims 1-4.

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