KR101403077B1 - Solar cell module and method for manufacturing same - Google Patents

Abstract

In the solar cell module in which a plurality of solar cells are connected in series and at least one surface electrode of the solar cell is connected to the tap line, the surface electrodes and the tab lines of the solar cell are dispersed in the binder resin composition And is connected by a thermocompression bonding process via a conductive adhesive layer. 50% by mass or more of the conductive particles is a flake having a long diameter of 1 to 50 占 퐉, a thickness of 5 占 퐉 or less and an aspect ratio of 3 to 150 (= long diameter / thickness) Shaped metal particles.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a solar cell module,

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

The solar cell module is formed by connecting a plurality of solar cells in series, and the surface electrode of the at least one solar cell is connected to a tap line made of solder-coated ribbon-shaped copper foil. Specifically, in a crystal solar cell module, a bus bar electrode formed by screen printing of a silver paste on a light receiving surface of a solar battery cell, and a tap line functioning as an inner lead are connected by a soldering process, In the module, a tab line is connected as a power lead-out outer lead to the surface electrodes of the solar cell at both ends by soldering (Patent Document 1).

However, due to the heating during the soldering process, the solar cell is warped and internal stress is generated in the connection portion between the tab line and the surface electrode. As a result, the connection reliability between the surface electrode of the solar cell and the tab line Is lowered.

Thus, recently, a conductive adhesive film which can be connected by thermocompression bonding at a relatively low temperature has been used for connection between the surface electrode of the solar cell and the tab line (Patent Document 2). As such a conductive adhesive film, spherical conductive particles having an average particle diameter on the order of several micrometers are dispersed in a thermosetting binder resin composition to form a film. As the spherical conductive particles, spherical metal particles having relatively high hardness and metal spheroidal resin particles having relatively low hardness are used.

Japanese Laid-Open Patent Publication No. 2004-356349 Japanese Laid-Open Patent Publication No. 2008-135654

However, since most of the surface electrodes of the solar cell are formed by applying and heating a silver paste, surface irregularities of several micrometers are ordinarily formed on the surface of the surface electrode, and the diameter of the spherical conductive particles also varies.

Therefore, when spherical metal particles having relatively high hardness are used as the conductive particles to be blended in the conductive adhesive film, if the spherical metal particles having a relatively large particle diameter are sandwiched between the surface electrode and the tab line of the solar cell, The spherical metal particles can not contact the surface electrode and the tab line at the same time and do not contribute to the connection. As a result, the connection reliability between the surface electrode and the tab line is deteriorated.

On the other hand, in the case of using the metal plating-coated spherical resin particles of relatively low hardness, the metal plating-coated spherical resin particles sandwiched between the surface electrode and the tab line of the solar cell are flattened by the thermocompression- It is believed that none that does not contribute to the connection is present, or very little. However, in the case where the Al paste or Al vapor deposition film is applied instead of the silver paste in the material cost reduction surface of the surface electrode, the metal plating-coated spherical resin particles are deformed flat during the thermocompression bonding treatment at the time of connection, There is a problem that the reliability of connection between the surface electrode of the solar cell and the tab line is lowered.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art described above, and a solar cell module in which a plurality of solar cells are connected in series and surface electrodes of at least one solar cell are connected to a tap line, The connection reliability between the surface electrode and the tab line can be ensured irrespective of the presence or the surface irregularities of the electrode and the material.

The present inventors have found that conductive particles used for a conductive adhesive film, at least 50% by mass or more thereof, of flaky metal particles having a specific size and an aspect ratio and having a hardness higher than that of a surface electrode and a tap line, The present invention has been accomplished.

That is, the present invention is a solar cell module in which a plurality of solar cells are connected in series, in which at least one surface electrode of the solar cell is connected to a tap line,

A surface electrode and a tab line of the solar cell are connected by a thermocompression bonding process through a conductive adhesive layer in which conductive particles are dispersed in a binder resin composition and 50 mass% Like metal particles having a major diameter of 5 μm or less and an aspect ratio of 3 to 150 (= long diameter / thickness) and having a hardness higher than that of the first electrode, the second electrode and the tap line And a solar cell module.

The present invention also provides a method of manufacturing a solar cell module in which a plurality of solar cells are connected in series and surface electrodes of at least one solar cell are connected to a tap line,

A step of laminating a conductive adhesive layer in which conductive particles are dispersed in a binder resin composition, on a surface electrode of the solar cell;

A step of disposing a tab line on the conductive adhesive layer; And

And a step of electrically connecting the surface electrode of the solar cell and the tab line by thermocompression bonding from the side of the tab on the conductive adhesive layer,

Wherein at least 50 mass% of the conductive particles have a long diameter of 1 to 50 占 퐉, a thickness of 5 占 퐉 or less and a flake having a aspect ratio of 3 to 150 (= long diameter / thickness) Shaped metal particles. The present invention also provides a method of manufacturing a solar cell module.

Further, the present invention is a conductive adhesive for connecting a surface electrode of at least one solar cell of a solar cell module in which a plurality of solar cells are connected in series with a tap line, wherein conductive particles are dispersed in the binder resin composition And 50% or more by mass of the conductive particles have a long diameter of 1 to 50 占 퐉, a thickness of 5 占 퐉 or less and an aspect ratio of 3 to 150 (= long diameter / thickness) Like conductive particles, and the conductive adhesive is a flake-shaped metal particle.

1. A solar cell module comprising a conductive adhesive film, a plurality of solar cells connected in series, and at least one surface electrode of the solar cell connected to a tap line, Shaped metal particles having a long diameter of 1 to 50 mu m, a thickness of 5 mu m or less, and an aspect ratio (= long diameter / thickness) of 3 to 150 are used at least 50 mass% or more. Since such flaky metal particles have a flat shape, they can be overlapped with each other when sandwiched between the surface electrodes of the solar cell and the tab line. Therefore, it is possible to eliminate the number of conductive particles not involved in connection, Can be reduced. Therefore, it is possible to secure good connection reliability regardless of the presence or absence of surface irregularities of the electrode commonly used in the solar cell.

The flaky metal particles have a higher hardness than the surface electrodes and the tab lines of the solar cell. Therefore, even when an Al paste or an Al vapor deposited film is used to form these electrodes, the surface passivation film of aluminum can be destroyed during the thermocompression bonding process, and good connection reliability can be ensured. In addition, good adhesion can be secured even for a curable Ag paste electrode such as an Ag powder kneaded with an epoxy resin.

1 is a schematic partial cross-sectional view of a solar cell module according to the present invention.
2 is a schematic overall sectional view of the solar cell module of the present invention.
3 is a schematic top view of the solar cell module of the present invention.
4 is a schematic perspective view of the flaky metal particles.

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

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

A solar cell to which the present invention is applied has a photoelectric conversion element as a photoelectric conversion portion. Examples of the photoelectric conversion element include a silicon-based photoelectric conversion element such as a monocrystalline silicon photoelectric conversion element, a polycrystalline silicon photoelectric conversion element, a microcrystalline silicon photoelectric conversion element, an amorphous silicon type solar cell element, Photoelectric conversion elements of other semiconductor compound systems such as a chalcopyrite type, dye-based photoelectric conversion elements such as dye-sensitized solar cells, and the like can be used. An ITO thin film electrode may be formed on the surface of these electrodes as needed.

The solar cell composed of these photoelectric conversion elements can be broadly divided into a thin film solar cell and other crystal solar cell.

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

1 is a schematic partial cross-sectional view of a solar cell module 100 of the present invention. In this solar cell module 100, a plurality of solar cells 50 are connected in series by a lead wire 30 functioning as an interconnector. Here, the solar cell 50 includes a photoelectric conversion element 10, a first electrode 21 which is a bus bar electrode which is a surface electrode formed on the light receiving surface thereof, and a second electrode 23 which is a bus bar electrode formed on the non- And finger electrodes 22 and 24 serving as collector electrodes formed on the photoelectric conversion element 10 so as to be substantially perpendicular to the first and second electrodes.

2, the solar cell module 100 of FIG. 1 typically includes a metal frame 200 such as aluminum, a light-transmitting surface protection material 201 such as glass or translucent plastic, Is encapsulated by a transparent encapsulant 203 such as ethylene vinyl alcohol resin (EVA) in a space formed by a backing material 202 such as a laminate sandwiched by a resin film.

In the solar cell module of the present invention having such a structure, as shown in Fig. 1, the tab line 30, the first electrode 21 and the second electrode 23 are electrically connected to each other by conductive Bonded via a bonding layer 40 by a thermocompression bonding process.

In the present invention, as the conductive particles, flat flake-like metal particles are used. The flat flake-like metal particles can be overlapped with each other when sandwiched between the first electrode or the second electrode and the tab line on the light receiving surface of the solar cell, and therefore, the number of conductive particles not involved in connection can be eliminated or So that it is possible to secure good connection reliability irrespective of the presence or absence of surface irregularities of the ordinary electrode used in the solar cell.

As the flake-shaped metal particles, flake-shaped metal particles of a metal or alloy such as nickel, silver and solder can be used. Among them, flake-shaped nickel particles can be preferably used at low cost and good conductivity.

The flaky metal particles used in the present invention have a long diameter of 1 to 50 mu m, preferably 1 to 40 mu m, and a thickness of 5 mu m or less, preferably 3 mu m or less. With respect to the long diameter, if it is less than 1 mu m, the conduction resistance after connection tends to increase. When the thickness is more than 50 mu m, there is a tendency that a problem occurs in the film application property when the film is molded. With respect to the thickness, when the thickness exceeds 5 탆, the insulation resistance tends to be lowered. The long diameter and the thickness of the flaky metal particles are numerical values measured by observing the appearance by a microscope or the like.

The flaky metal particles used in the present invention have an aspect ratio (that is, a numerical value obtained by dividing the long diameter (L) by the thickness (T)) of 3 to 150, preferably 3 to 100 will be. With respect to the aspect ratio, when the ratio exceeds 150, the conduction resistance after connection tends to increase.

The flaky metal particles exhibit higher hardness than the first electrode on the light receiving surface of the solar cell, the second electrode on the non-light receiving surface, and the tab line. Therefore, even when an Al paste or an Al vapor-deposited film is used to form these electrodes, the surface passivation film of aluminum can be destroyed in the thermocompression bonding process, and it is possible to penetrate into the tab line, thereby securing good connection reliability .

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

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

As the binder resin composition constituting the conductive adhesive layer 40, a thermosetting binder resin composition used in conventional conductive adhesives can be appropriately selected and used. For example, a binder resin composition comprising a thermosetting epoxy resin, a thermosetting urea resin, a thermosetting melamine resin, a thermosetting phenol resin, or the like is blended with a curing agent such as an imidazole-based curing agent or an amine-based curing agent. Among them, a binder resin composition using a thermosetting epoxy resin can be preferably used in view of the good bonding strength after curing.

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

The binder resin composition used in the present invention may contain a filler such as silica and mica, a pigment, an antistatic agent and the like if necessary. A coloring agent, a preservative, a polyisocyanate-based cross-linking agent, and a silane coupling agent.

In addition, known spherical or indefinite conductive particles may be blended. When the spherical conductive particles are added to the flaky metal particles in addition to the effect that the conduction resistance value can be further stabilized and the production cost of the conductive adhesive can be reduced by reducing the amount of the flaky metal particles used Loses. The spherical conductive particles preferably have an average particle diameter of 1 to 10 탆 and smaller than the long diameter of the flaky metal particles. The amount of the spherical or amorphous conductive particles to be blended is preferably 0.01 to 1 times the blending amount (mass part) of the flaky metal particles.

The conductive adhesive layer 40 in the present invention is used as a paste-like conductive adhesive or a film-shaped conductive adhesive film. When the melt viscosity is too low, the conductive adhesive layer 40 flows from the temporary pressing to the final curing process, It is easy to come out to the surface. The viscosity at 25 ° C measured by a cone plate type viscometer is preferably 50 to 200 Pa 揃 s, more preferably 50 to 150 Pa 揃 s, as measured by a cone plate type viscometer, in the case of a paste, Pa. In the case of a film, the minimum melt viscosity measured by a cone plate type viscometer is preferably 1 x 10 ² to 1 x 10 ⁵ Pa s, more preferably 1 x 10 ² to 5 x 10 ⁴ Pa s.

In the present invention, the conductive adhesive layer 40 is formed by applying a conductive adhesive in which conductive particles are uniformly dispersed in a thermosetting binder resin composition according to a conventional method, to a first electrode and a second electrode of a solar cell, . It is also possible to form the conductive adhesive layer of the conductive adhesive film obtained by forming the conductive adhesive on the peelable base film and drying the conductive adhesive layer to the first electrode and the second electrode. Such a conductive adhesive is useful for providing a conductive adhesive for connecting a surface electrode of at least one solar cell of a solar cell module in which a plurality of solar cells are connected in series with a tap line, and is included in the present invention .

The thickness of the conductive adhesive layer 40 is preferably from 5 to 50 mu m, more preferably from 10 to 40 mu m, because the thickness of the conductive adhesive layer 40 may become insufficient when the thickness is excessively small, to be.

The first electrode 21 on the light receiving surface of the solar cell 50 and the second electrode 23 on the non-light receiving surface may have the same configuration as the bus bar electrode of the conventionally known solar battery cell. For example, it is formed by applying silver paste or Al paste and heating.

For example, the first electrode 21 formed on the light receiving surface of the solar cell 50 is generally formed in a line shape with a width of about 1 mm in order to reduce an area for shielding incident light as much as possible. The number of the first electrodes 21 is appropriately set in consideration of the size and resistance of the solar cell. In the same manner, line-shaped finger electrodes 22 having a width of about 100 mu m are formed in substantially the entire area of the light receiving surface of the photoelectric conversion element 10 so as to cross the first electrode, .

The second electrode 23 and the finger electrode 24 formed on the non-light receiving surface of the solar cell 50 also have the same configuration as the first electrode 21 and the finger electrode 22 formed on the light receiving surface . The second electrode on the non-light-receiving surface may be formed so as to cover substantially the entire surface of the back surface of the photoelectric conversion element 10, since it is unnecessary to consider the incident light. In this case, the finger electrode 24 becomes unnecessary.

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

As described above, the first electrode, the second electrode, and the tab line 30 use a material that is softer than the flake-shaped metal particles. For example, when the flaky metal particles are nickel particles (Mohs hardness = 3.5), at least the surfaces of the first electrode, the second electrode and the tab line are gold (Mohs hardness = 2.5) ), Copper (Mohs hardness = 3.0), aluminum (Mohs hardness = 2.9) and tin (Mohs hardness = 3.0).

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

A conductive adhesive in which conductive particles containing 50% by mass or more of predetermined flake-shaped metal particles are dispersed in an epoxy resin composition is applied on a release film so as to have a dry thickness of 10 to 40 占 퐉 and dried to form a conductive adhesive film .

The conductive adhesive layer of the conductive adhesive film is temporarily pressed against the first electrode and the second electrode of the solar cell and the conductive adhesive layer is laminated on the first electrode and the second electrode by peeling off the release film.

The conductive adhesive layer may be formed on the first electrode and the second electrode by a screen printing method or the like in accordance with the shape of the paste without forming the conductive adhesive into a film.

Next, a tap wire is disposed on the second electrode on the non-light-receiving surface of the solar cell adjacent to the first electrode on the light-receiving surface of the solar cell, and is heated at 30 to 120 DEG C for 0.2 to 10 seconds And the pressure bonding is performed by heating at 140 to 200 DEG C for 10 to 20 seconds while pressurizing to about 0.1 to 5 MPa, thereby connecting the plurality of solar cells in series. When a paste-like conductive adhesive is used, the temporary adhering step may be omitted.

Next, a light-transmissive surface protecting material such as glass, a sealing sheet such as EVA, a plurality of solar cell cells connected in series, an encapsulating sheet such as EVA, and a backing material are stacked in this order and vacuumed. Laminate for 5 to 20 minutes. Then, it is completely cured by heating at 120 to 150 ° C for 30 to 60 minutes. Thereafter, a terminal box and a metal frame are mounted to obtain a solar cell module.

Next, an example of the solar cell module of the present invention using the thin-film solar cell will be described with reference to Fig. Such a thin-film solar cell module has a structure in which a long thin film-type photoelectric conversion element is directly connected in the lateral direction, a power lead-out line is connected to the electrode of the photoelectric conversion element, The resin is encapsulated.

The thin-film solar cell module 100 of FIG. 3 has thin-film solar cells 32 made of thin-film photoelectric conversion elements arranged in series in a plane direction on a base material 38, (Not shown) of the cell 32c and the surface lead electrode (not shown) of the solar cell 32d at the other end are connected to each other via the adhesive. The construction other than the use of the thin film type solar cell 32 and the construction in which the tab lines are not used for connecting the solar cells to each other is principally the same as the case of the crystal solar cell module described with reference to Fig.

Such a thin film solar cell module has a structure in which a surface electrode (not shown) of the solar cell 32c at one end and a surface electrode (not shown) of the solar cell 32d at the other end are connected to a power- (About 140 to 200 占 폚) by temporarily pressing the substrate 34 at a room temperature or a low temperature (about 30 to 120 占 폚) through the adhesive described in the crystalline solar cell module of Fig. 1 have.

A plurality of solar cell modules thus obtained are connected in series to produce a solar cell string, and a plurality of such solar cell strings are prepared and connected in parallel to obtain a solar cell array .

The conductive adhesive used in the present invention, that is, the conductive adhesive for connecting the surface electrodes of at least one solar cell of the solar cell module in which a plurality of solar cells are connected in series to the tap wires is also part of the present invention, It is characterized in that conductive particles are dispersed in a binder resin composition and 50% by mass or more of the conductive particles have a long diameter of 1 to 50 占 퐉, a thickness of 5 占 퐉 or less and an aspect ratio of 3 to 150 (= long diameter / Shaped metal particles having a higher hardness than the surface electrodes and the tap lines. The specific configuration is as described above.

Example

Hereinafter, the solar cell module of the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to those shown in the following examples, .

Example 1

(1) Production of a conductive adhesive film

10 parts by mass of conductive particles containing 50% by mass or more of scaly Ni particles (Mohs hardness 3.8) having a major diameter of 1 to 20 占 퐉, a thickness of 3 占 퐉 or less and an aspect ratio of 3 to 50, a bis type A epoxy resin (EP828, Japan Epoxy 20 parts by mass of a phenoxy resin (YP-50, Toto Chemical Co., Ltd.) and 20 parts by mass of an imidazole type latent curing agent (HX3941HP, Asahi Chemical Industry Co., Ltd.) 100 parts by weight of a conductive adhesive was prepared.

The obtained conductive adhesive was coated on a peeled polyethylene terephthalate film having a thickness of 50 占 퐉 so as to have a thickness of 25 占 퐉 and dried by heating in an oven at 80 占 폚 for 5 minutes to form a conductive adhesive film.

(2) Production of solar cell module model

(2a) As a substitute for the photoelectric conversion element, three types of glass plates having the dimensions of 80 mm in length, 15 mm in width and 0.7 mm in thickness were prepared.

An ITO beta glass plate in which an indium-titanium composite oxide layer having a thickness of 150 to 200 nm was formed as a (2ai) electrode was prepared. The Mohs hardness of the ITO surface was 4 or more. The roughness of the electrode surface was 0.2 mu m or less.

(2a ii) An Al beta glass plate on which an aluminum vapor-deposited film having a thickness of 500 nm was formed as an electrode was prepared. The Mo hardness of the Al surface was 2.9. The roughness of the electrode surface was 0.2 mu m or less. Further, a strong passivation film was formed on the surface of aluminum.

(2a ii) An Ag beta glass plate having an Ag paste fired film having a thickness of 5 탆 was formed as an electrode. The Mo hardness of the Ag surface was 2.7. The roughness of the electrode surface was 4 占 퐉 or less. In addition, a weak oxide film was formed on the surface of Ag.

(2b) On the other hand, the following two types of tap lines were prepared as the tap lines.

(2bi) A solder-coated copper ribbon was prepared by subjecting a copper foil having a thickness of 150 mu m to SnAgCu solder dip plating (plating thickness: 40 mu m). The Mohs hardness of the surface was 3 or less.

(2bii) 150 탆 thick solid copper ribbon was used as the tap line. The Mohs hardness of the surface was 3.

(2c) A solar cell module model was manufactured by thermally compressing the conductive adhesive layer of the conductive adhesive film to the electrode layer as a substitute for the photoelectric conversion element at 12 points (connecting area: 2 mm square, 180 캜, 3 MPa, 15 seconds) . With respect to the obtained solar cell module model, the maximum resistance value and the minimum resistance value were measured by the four-terminal method, the average resistance value was calculated, and the average resistance value was evaluated based on the criteria shown in Table 1 below. The obtained results are shown in Table 2.

electrode Judgment rank Solder coating Cu (Ω) Solid Cu (Ω)
ITO
 A  Less than 1.2  0.8  B  1.2 to less than 1.3  0.8 or more to less than 0.9  C  1.3 or higher  0.9 or more
Al Beta
 A  Less than 0.03  Less than 0.02  B  0.03 or more and less than 0.04  0.02 or more and less than 0.04  C  0.04 or more  0.04 or more
Ag beta
 A  Less than 0.005  Less than 0.005  B  0.005 or more to less than 0.010  0.005 or more to less than 0.010  C  0.010 or more  0.010 or more

Example 2

Except for using conductive particles containing not less than 50 mass% of scaly Ni particles having a major diameter of 20 to 40 占 퐉, a thickness of 3 占 퐉 or less and an aspect ratio of 50 to 100 as the scaly Ni particles (Mohs hardness 3.8) 1 was repeated to fabricate a conductive adhesive film and a solar cell module model. With respect to the obtained solar cell module model, the maximum resistance value and the minimum resistance value were measured by the four-terminal method, and the average resistance value was calculated and evaluated on the same basis. The obtained results are shown in Table 2.

Example 3

Except for using conductive particles containing 50% by mass or more of scaly Ni particles (Mohs hardness 3.8) having a long diameter of 40 to 50 占 퐉, a thickness of 3 占 퐉 or less and an aspect ratio of 100 to 150 as scaly Ni particles, 1 was repeated to fabricate a conductive adhesive film and a solar cell module model. With respect to the obtained solar cell module model, the maximum resistance value and the minimum resistance value were measured by the four-terminal method, and the average resistance value was calculated and evaluated on the same basis. The obtained results are shown in Table 2.

Comparative Example 1

A conductive adhesive film and a solar cell module model were fabricated by repeating Example 1, except that spherical Ni particles having an average particle size of 10 占 퐉 (Mohs hardness 3.8) were used instead of scaly Ni particles. With respect to the obtained solar cell module model, the maximum resistance value and the minimum resistance value were measured by the four-terminal method, and the average resistance value was calculated and evaluated on the same basis. The obtained results are shown in Table 2.

Comparative Example 2

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

As can be seen from Table 2, in the solar cell module models of Examples 1 to 3 using the conductive adhesive film containing the flat flake metal particles having the long diameter, the thickness and the aspect ratio in the specific range as the conductive particles, The electrode material (ITO electrode, Al vapor deposition electrode, silver paste electrode) ordinarily formed in the conversion element and the tab line (SnAgCu solder-coated copper ribbon, monocurium ribbon) conventionally used for connecting the solar cells to each other, It can be seen that they are connected while ensuring good reliability by the thermocompression bonding process. Among them, it is preferable that the aspect ratio is in the range of 3 to 50 (not including 50) and 50 to 100.

On the other hand, in the case of Comparative Example 1 using relatively hard spherical Ni particles among spherical conductive metal particles instead of flat flake-like metal particles, spherical Ni particles are not deformed well at the time of thermocompression bonding. This is presumed to be due to the fact that particles having a relatively small particle size are present, and particles having a small particle size can not contribute to the connection. Therefore, when ITO was used as the electrode material, the evaluation of the conduction reliability was C. However, when the Ag paste electrode whose electrode material is relatively soft was used, the silver paste electrode side was deformed such that the spherical Ni particles deeply penetrated toward the silver paste electrode Therefore, it can be seen that there is no problem in conduction reliability. Further, even when an aluminum paste electrode having a passivation film formed on the surface thereof is used, since the passivation film can be torn at the time of thermocompression bonding, there is no problem in conduction reliability.

In the case of Comparative Example 2 using relatively soft spherical solder particles among spherical conductive metal particles instead of flat flake-like metal particles, since it is deformed at the time of thermocompression bonding, when ITO is used as the electrode material, It can be seen that there is no problem in conduction reliability. However, when an aluminum paste electrode having a passivation film formed on the surface thereof is used, the passivation film can not be torn at the time of thermocompression bonding, which indicates a problem in conduction reliability.

Industrial availability

The solar cell module of the present invention is a solar cell module in which a connection conductive adhesive film is used as a bonding material of an electrode and a tap line, and further conductive particles to be mixed therewith include at least 50 mass% or more of a long diameter of 1 to 50 탆, , And flake-shaped metal particles having an aspect ratio of 3 to 150 are used. Therefore, good connection reliability can be ensured irrespective of whether or not the surface of the electrode of the solar cell is uneven. The flaky metal particles have a higher hardness than the surface electrodes and the tap lines. Therefore, even when an Al paste or an Al vapor deposition film is used to form these electrodes, the surface passivation film of aluminum can be destroyed during the thermocompression bonding process, and good connection reliability can be ensured.

10: Photoelectric conversion element
21: first electrode
22, 24: finger electrodes
23: Second electrode
30, 34:
32: Thin Film Solar Cell
38: substrate
40: conductive adhesive layer
50: Solar cell
100: solar cell module
200: metal frame
201: Light-transmitting surface protection material
202: backing protection material
203: Transparent encapsulant

Claims (9)

1. A solar cell module comprising a plurality of solar cells connected in series, wherein at least one surface electrode of the solar cell is electrically connected to a tap line,
The surface electrode and the tab line of the solar cell are connected to each other by thermocompression bonding using a conductive adhesive in which conductive particles are dispersed in the binder resin composition,
Wherein 50% by mass or more of the conductive particles have a major axis of 1 to 20 占 퐉, a thickness of 3 占 퐉 or less and an aspect ratio of 3 to 50 (= long diameter / thickness) And has a long diameter of 3 탆 or less and an aspect ratio of 50 to 100 (= long diameter / thickness), and the conductive particles are in the form of a flake having a higher hardness than the surface electrode and the tap line of the solar cell Nickel particles. A method of manufacturing a solar cell module in which a plurality of solar cells are connected in series and surface electrodes of at least one solar cell are connected to a tap line,
A step of laminating a conductive adhesive layer in which conductive particles are dispersed in a binder resin composition on the surface electrodes of the solar cell, wherein 50% by mass or more of the conductive particles have a long diameter of 1 to 20 占 퐉, , A thickness of not more than 3 mu m and an aspect ratio of 3 to 50 (= long diameter / thickness), or a long diameter of 20 to 40 mu m, a thickness of 3 mu m or less and an aspect ratio of 50 to 100 (= Long diameter / thickness), and the conductive particles are flaky nickel particles having a higher hardness than the surface electrodes and the tab lines of the solar cell;
Disposing a tab line on the conductive adhesive layer; And
And a step of thermally compressing the surface of the conductive adhesive layer from the side of the tab line to electrically connect the surface electrode and the tab line of the solar cell. 1. A conductive adhesive for connecting a surface electrode of at least one solar cell of a solar cell module in which a plurality of solar cells are connected in series with a tap line, wherein conductive particles are dispersed in the binder resin composition,
Wherein at least 50% by mass of the conductive particles have a long diameter of 1 to 20 占 퐉, a thickness of 3 占 퐉 or less and an aspect ratio of 3 to 50 (= long diameter / thickness) or a long diameter of 20 to 40 占 퐉 Shaped nickel particles having a thickness of 3 탆 or less and an aspect ratio of 50 to 100 (= long diameter / thickness) and having a hardness higher than that of the surface electrode and the tab line, glue. 1. A solar cell module comprising a plurality of solar cells connected in series, wherein at least one surface electrode of the solar cell is electrically connected to a tap line,
The surface electrode and the tab line of the solar cell are connected to each other by thermocompression bonding using a conductive adhesive in which conductive particles are dispersed in the binder resin composition,
Wherein the surface electrode of the cell of the solar cell is formed of aluminum,
Wherein 50% by mass or more of the conductive particles have a major axis of 1 to 20 占 퐉, a thickness of 3 占 퐉 or less and an aspect ratio of 3 to 50 (= long diameter / thickness) And has a long diameter of 3 탆 or less and an aspect ratio of 50 to 100 (= long diameter / thickness), and the conductive particles are in the form of a flake having a higher hardness than the surface electrode and the tap line of the solar cell Nickel particles. A method of manufacturing a solar cell module in which a plurality of solar cells are connected in series and surface electrodes of at least one solar cell are connected to a tap line,
A step of laminating a conductive adhesive layer in which conductive particles are dispersed in a binder resin composition on a surface electrode of the solar cell, wherein the surface electrode of the cell of the solar cell is made of aluminum, % Or more, a major axis of 1 to 20 占 퐉, a thickness of 3 占 퐉 or less, an aspect ratio of 3 to 50 (= long diameter / thickness), or a long axis of 20 to 40 占 퐉, Shaped nickel particles having a thickness of 3 탆 or less, an aspect ratio of 50 to 100 (= long diameter / thickness), and the conductive particles having a higher hardness than the surface electrodes and the tab lines of the solar cell;
Disposing a tab line on the conductive adhesive layer; And
And a step of thermally compressing the surface of the conductive adhesive layer from the side of the tab line to electrically connect the surface electrode and the tab line of the solar cell. A conductive adhesive for connecting a surface electrode formed of aluminum to at least one solar cell cell of a solar cell module in which a plurality of solar cells are connected in series with a tap line is characterized in that conductive particles are dispersed in a binder resin composition ,
Wherein at least 50% by mass of the conductive particles have a long diameter of 1 to 20 占 퐉, a thickness of 3 占 퐉 or less and an aspect ratio of 3 to 50 (= long diameter / thickness) or a long diameter of 20 to 40 占 퐉 Shaped nickel particles having a thickness of 3 탆 or less and an aspect ratio of 50 to 100 (= long diameter / thickness) and having a hardness higher than that of the surface electrode and the tab line, glue. 1. A solar cell module comprising a plurality of solar cells connected in series, wherein at least one surface electrode of the solar cell is electrically connected to a tap line,
The surface electrode and the tab line of the solar cell are connected to each other by thermocompression bonding using a conductive adhesive in which conductive particles are dispersed in the binder resin composition,
Wherein 50% by mass or more of the conductive particles have a major axis of 1 to 20 占 퐉, a thickness of 3 占 퐉 or less and an aspect ratio of 3 to 50 (= long diameter / thickness) And a thickness of 3 탆 or less and an aspect ratio of 50 to 100 (= long diameter / thickness), and the conductive particles are flaked nickel having a higher hardness than the surface electrodes and the tap wires of the solar cell And the conductive particles break the passive film of the surface electrode and penetrate into the tapped line. A method of manufacturing a solar cell module in which a plurality of solar cells are connected in series and surface electrodes of at least one solar cell are connected to a tap line,
A step of laminating a conductive adhesive layer in which conductive particles are dispersed in a binder resin composition on the surface electrodes of the solar cell, wherein 50% by mass or more of the conductive particles have a long diameter of 1 to 20 占 퐉, , A thickness of not more than 3 mu m and an aspect ratio of 3 to 50 (= long diameter / thickness), or a long diameter of 20 to 40 mu m, a thickness of 3 mu m or less and an aspect ratio of 50 to 100 (= Long diameter / thickness), and the conductive particles are flaky nickel particles having a higher hardness than the surface electrodes and the tab lines of the solar cell;
Disposing a tab line on the conductive adhesive layer; And
And a step of thermally compressing the conductive particles from the side of the tab on the conductive adhesive layer to break the passive film of the surface electrode and to penetrate the tab line to electrically connect the surface electrode and the tab line of the solar cell. Gt; 1. A conductive adhesive for connecting a surface electrode of at least one solar cell of a solar cell module in which a plurality of solar cells are connected in series with a tap line, wherein conductive particles are dispersed in the binder resin composition,
Wherein at least 50% by mass of the conductive particles have a long diameter of 1 to 20 占 퐉, a thickness of 3 占 퐉 or less and an aspect ratio of 3 to 50 (= long diameter / thickness) or a long diameter of 20 to 40 占 퐉 And a thickness of 3 탆 or less and an aspect ratio of 50 to 100 (= long diameter / thickness), and the conductive particles break the passive film of the surface electrode by the thermocompression bonding process, Wherein the conductive particles are flake-shaped nickel particles having a higher hardness than the surface electrodes and the tap wires.

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