JP2013074259A - Laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To connect an interconnector to an electrode such as a bus-bar electrode with excellent adhesiveness without soldering.SOLUTION: The laminate comprises: a first electrode conductive layer formed by performing a thermal treatment at a temperature of 400°C or higher on a conductive composition for a first electrode which contains conductive particles (A) such that silver-coated metal powder (a) accounts for 25-100 mass% thereof; and an adhesive conductive layer disposed on the first electrode conductive layer, and formed by a conductive composition for adhesive bonding which contains a binder resin (B) and conductive particles (C).

Description

  The present invention relates to a laminate.

Conventionally, various conductive compositions have been used as materials that are baked to form electrodes and the like.
For example, Patent Document 1 states that “a metal material (A) having an electrical resistivity of 20 × 10 ⁻⁶ Ω · cm or less, a fatty acid silver salt (B) having one or more hydroxyl groups, and a boiling point of 200 ° C. or less. A secondary fatty acid silver salt (C) obtained by using a secondary fatty acid and a conductive composition containing the secondary fatty acid silver salt (C) "is disclosed ([Claim 1]). ] Is used ([Example] [0071]).

  Patent Document 2 discloses that “in a silver simple substance and a silver compound containing silver powder (A), silver oxide (B), and an organic solvent (D), and the silver powder (A) is contained in the composition. "Conductive composition of 50% by mass or more" has been proposed ([Claim 1]), which includes silver carboxylate as an optional component, and other additives such as glass frit and metallic additives. Aspects are described ([Claim 2] [0030] [0033] [0034] and the like).

JP 2010-92684 A JP 2011-35062 A

The conductive composition containing silver powder has a problem of high cost while having high performance such as excellent conductivity after firing, and high cost.
The inventors of the present invention have studied to reduce the cost of the conductive composition, and instead of using silver powder or a part of silver powder, silver coated metal powder such as silver coated nickel powder is used to reduce the cost. It was clarified that can be realized.

By the way, in the photovoltaic cell, the conductive composition as described above is printed and then baked to form electrodes (finger electrodes, bus bar electrodes, etc.). And the bus-bar electrode in one photovoltaic cell and the connection part of the back surface electrode in another photovoltaic cell are connected by an interconnector (for example, copper ribbon etc.), and a photovoltaic module is formed.
At this time, the bus bar electrode and the interconnector are generally connected by soldering.

However, for example, when a conductive composition containing silver-coated nickel powder is fired, the nickel portion exposed from the gaps in the silver coat is oxidized during firing, which may result in poor solder adhesion. The present inventors have found out.
In this case, the adhesiveness (interconnector adhesiveness) of the interconnector to the bus bar electrode by soldering is inferior, which is not preferable.

  Accordingly, an object of the present invention is to connect an interconnector to an electrode such as a bus bar electrode with excellent adhesiveness without using soldering.

As a result of intensive studies to achieve the above object, the present inventor has found that an interconnector can be connected to a layer as an electrode via a specific layer, and has completed the present invention.
That is, the present invention provides the following (1) to (9).

  (1) A first electrode conductive composition containing conductive particles (A) in which 25 to 100% by mass is silver-coated metal powder (a) is formed by heat-treating at a temperature of 400 ° C. or higher. An electrode conductive layer, an adhesive conductive layer disposed on the first electrode conductive layer, and formed using an adhesive conductive composition containing a binder resin (B) and conductive particles (C); A laminate comprising:

  (2) A second electrode conductive composition containing conductive particles (A) in which 25 to 100% by mass is silver-coated metal powder (a) and a binder resin (B) is heated to a temperature of 150 ° C. or higher and 400 ° C. A conductive composition for bonding comprising a second electrode conductive layer formed by heat treatment at a temperature less than that, and the binder resin (B) and conductive particles (C) disposed on the second electrode conductive layer. An adhesive conductive layer formed using the laminate.

  (3) The laminate according to (1) or (2), wherein the silver-coated metal powder (a) has an average particle size of 1.5 to 20 μm.

  (4) In any one of the above (1) to (3), the silver-coated metal powder (a) is a silver-coated nickel powder having a silver coat of 5 to 30 parts by mass with respect to 100 parts by mass of the nickel powder. The laminated body of description.

  (5) The laminate according to any one of (1) to (4), wherein the conductive particles (A) other than the silver-coated metal powder (a) are silver powder.

  (6) Said (1)-(5) whose said electroconductive particle (C) is at least 1 sort (s) chosen from the group which consists of silver powder, nickel powder, copper powder, silver coat nickel powder, and silver coat copper powder. ).

  (7) The laminate according to any one of (1) to (6), wherein the conductive particles (C) have an average particle diameter of 1.5 to 20 μm.

  (8) Any of the above (1) to (7), wherein the binder resin (B) includes at least one selected from the group consisting of an epoxy resin, a polyester resin, a urethane resin, a phenol resin, and a polyimide resin. The laminated body as described in.

  (9) The laminated body according to any one of (1) to (8), further including an interconnector disposed on the adhesive conductive layer.

  According to the present invention, an interconnector can be connected to an electrode such as a bus bar electrode with excellent adhesiveness without using soldering.

It is a schematic cross section of a photovoltaic cell. It is the model top view seen from the surface electrode side of the photovoltaic cell, and the model bottom view seen from the back electrode side. It is the model perspective view of a solar cell module, and the expanded sectional view of a junction part.

[Laminate]
The laminated body of the 1st aspect of this invention is the temperature of 400 degreeC or more for the 1st electroconductive composition containing the electroconductive particle (A) whose 25-100 mass% is a silver coat metal powder (a). A first electrode conductive layer formed by heat treatment with a conductive composition for bonding, which is disposed on the first electrode conductive layer and contains a binder resin (B) and conductive particles (C) And an adhesive conductive layer formed.

  On the other hand, the laminate of the second aspect of the present invention is a second electrode conductive material containing conductive particles (A) in which 25 to 100% by mass is silver-coated metal powder (a) and binder resin (B). A second electrode conductive layer formed by heat-treating the composition at a temperature of 150 ° C. or higher and lower than 400 ° C., disposed on the second electrode conductive layer, and the binder resin (B) and conductive particles (C And an adhesive conductive layer formed using an adhesive conductive composition containing the adhesive.

  Below, first, each part with which the laminated body of the 1st aspect and 2nd aspect of this invention (henceforth these are collectively called "the laminated body of this invention") is demonstrated.

[First electrode conductive layer and second electrode conductive layer]
A 1st electrode conductive layer heat-processes the 1st electroconductive composition containing the electroconductive particle (A) whose 25-100 mass% is a silver coat metal powder (a) at the temperature of 400 degreeC or more. It is a layer formed.
On the other hand, the second electrode conductive layer comprises a second electrode conductive composition containing conductive particles (A) in which 25 to 100% by mass is silver-coated metal powder (a) and a binder resin (B). , A layer formed by heat treatment at a temperature of 150 ° C. or higher and lower than 400 ° C.
Therefore, first, the first and second conductive compositions for electrodes used for forming the first and second electrode conductive layers will be described first.

<First Electrode Conductive Composition and Second Electrode Conductive Composition>
The first electrode conductive composition is a composition containing conductive particles (A) in which 25 to 100% by mass is silver-coated metal powder (a).
On the other hand, the second electrode conductive composition is a composition containing conductive particles (A) and binder resin (B) in which 25 to 100% by mass is silver-coated metal powder (a).
Therefore, in the following, first, each component contained in the first and second electrode conductive compositions will be described.

(Conductive particles (A))
The conductive particles (A) are not particularly limited as long as 25 to 100% by mass of the conductive particles (A) is silver-coated metal powder (a). Therefore, first, the silver-coated metal powder (a) will be described.

  The silver-coated metal powder (a) is not particularly limited as long as at least a part of the surface of the metal powder is coated with silver. Here, examples of the metal powder include nickel powder, copper powder, aluminum powder, and magnesium powder. Among these, nickel powder is preferable because it is difficult to be oxidized during heat treatment.

The silver-coated metal powder (a) is preferably one in which silver is not unevenly distributed and is uniformly distributed over the entire surface, rather than one in which silver is unevenly distributed on a part of the surface. Thereby, it becomes a silver coat metal powder with uniform conductivity. Further, the coated silver may adhere to the surface of the metal powder in the form of a dot or mesh.
In the silver coat metal powder (a), the amount of silver (silver coat amount) that coats the surface of the metal powder such as nickel powder is 5 to 30 parts by mass with respect to 100 parts by mass of the metal powder from the viewpoint of conductivity. It is preferable that it is 20-30 parts by mass.
The average particle diameter of the silver-coated metal powder (a) is preferably 1.5 to 20 μm for reasons such as excellent printability, and 5 to 20 μm because the specific surface area is small and is not easily oxidized during heat treatment. More preferably.

In addition, in this specification, an average particle diameter means the average value of a particle diameter, and means the 50% volume cumulative diameter (D50) measured using the laser diffraction type particle size distribution measuring apparatus. In addition, when the cross section is an ellipse, the particle diameter used as the basis for calculating the average value means an average value obtained by dividing the total value of the major axis and the minor axis by 2, and when it is a regular circle, it means the diameter. .
The spherical shape refers to the shape of particles having a major axis / minor axis ratio of 2 or less.

(Silver powder)
The first and second electrode conductive compositions preferably contain no silver powder from the viewpoint of cost reduction, but contain silver powder as the conductive particles (A) from the viewpoint of conductivity and the like. It may be. That is, in this case, the conductive particles (A) other than the silver-coated metal powder (a) described above are silver powder.
As said silver powder, it is preferable that an average particle diameter is 0.5-10 micrometers from the reason that printability becomes favorable, It is more preferable that it is 0.7-5 micrometers, It is further 1-3 micrometers. preferable.
In addition, it is more preferable to use spherical silver powder because an electrode having a smaller volume resistivity can be formed and a photovoltaic cell with higher photoelectric conversion efficiency can be produced.
As such silver powder, commercially available products can be used. Specific examples thereof include AgC-102 (shape: spherical, average particle size: 1.5 μm, manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.), AgC-103 ( Shape: spherical, average particle size: 1.5 μm, manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., AG4-8F (shape: spherical, average particle size: 2.2 μm, manufactured by DOWA Electronics), AG2-1C (shape: spherical) , Average particle size: 1.0 μm, manufactured by DOWA Electronics Co., Ltd., AG3-11F (shape: spherical, average particle size: 1.4 μm, manufactured by DOWA Electronics Co., Ltd.), AgC-2011 (shape: flake shape, average particle size: 2-10 μm, manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.), AgC-301K (shape: flake shape, average particle size: 3-10 μm, manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.), and the like.

(solvent)
The first and second conductive compositions for electrodes may contain a solvent.
Although it does not specifically limit as said solvent, It is preferable that it is an organic solvent whose boiling point is 200 degreeC or more. Specific examples of the organic solvent having a boiling point of 200 ° C. or more include, for example, butyl carbitol, methyl ethyl ketone, isophorone, α-terpineol, triethylene glycol, and the like. May be used in combination.
The amount of the solvent is preferably 2 to 20 parts by mass and more preferably 5 to 15 parts by mass with respect to 100 parts by mass of the conductive particles (A) described above.

(Vehicle)
The first electrode conductive composition may contain a vehicle from the viewpoint of printability. The vehicle is not particularly limited as long as it is a resin dissolved in an organic solvent and can impart printability.
Specific examples of the resin in the vehicle include ethyl cellulose resin, nitrocellulose resin, alkyd resin, acrylic resin, styrene resin, phenol resin and the like. You may use together. Among these, it is preferable to use ethyl cellulose resin from the viewpoint of thermal decomposability.
Specific examples of the organic solvent in the vehicle include α-terpineol, butyl carbitol, butyl carbitol acetate, diacetone alcohol, and methyl isobutyl ketone. These may be used alone. Also, two or more of them may be used in combination.
The content of the vehicle is preferably 0 to 20 parts by mass, more preferably 0.3 to 20 parts by mass in solid content with respect to 100 parts by mass of the conductive particles (A) described above. .

(Binder resin (B))
The 2nd electrode conductive composition contains binder resin (B) from an adhesive viewpoint.
The binder resin (B) is not particularly limited, and examples thereof include an epoxy resin, a polyester resin, a urethane resin, a phenol resin, and a polyimide resin. These may be used alone or in combination of two or more. May be.
Of these, epoxy resins and polyester resins are preferred because they are superior in adhesion to the adherend.
It is preferable that content of binder resin (B) is 1-25 mass parts with respect to 100 mass parts of electroconductive particle (A) mentioned above, and it is more preferable that it is 5-15 mass parts.

In addition, although binder resin (B) may consist only of resin, such as an epoxy resin and a polyester resin mentioned above, it may contain other resin, an additive, etc. further.
More specifically, for example, the binder resin (B) further includes 15 to 35 parts by mass of core-shell type rubber particles, 10 to 30 parts by mass of phenoxy resin, with respect to 100 parts by mass of the resin such as an epoxy resin or a polyester resin. The solvent may contain 20 to 40 parts by mass, silica 0.5 to 1.5 parts by mass, silane coupling agent 0.5 to 1.5 parts by mass, and curing agent 1 to 3 parts by mass.

(Glass frit)
The first electrode conductive composition may contain glass frit as necessary.
Although it does not specifically limit as said glass frit, It is preferable that it is a glass frit which does not contain lead oxide, For example, the borosilicate glass frit etc. of the softening temperature of 300-800 degreeC are mentioned.
The shape of the glass frit is not particularly limited, and may be spherical or crushed powder. The average particle diameter (D50) of the spherical glass frit is preferably 0.1 to 20 μm, and more preferably 1 to 10 μm. Furthermore, it is preferable to use a glass frit having a sharp particle size distribution from which particles of 15 μm or more are removed.
The content of the glass frit is preferably 0.5 to 5 parts by mass and more preferably 1 to 3 parts by mass with respect to 100 parts by mass of the conductive particles (A).

(Method for producing first and second conductive compositions for electrodes)
The manufacturing method of the 1st and 2nd electroconductive composition for electrodes is not specifically limited, For example, the method of mixing the essential component mentioned above and arbitrary components using a ball mill etc. is mentioned.

<Method for Manufacturing First Electrode Conductive Layer>
The manufacturing method of the first electrode conductive layer includes at least a step of heat-treating the above-described first electrode conductive composition at a temperature of 400 ° C. or higher.
By the heat treatment, the first electrode conductive composition is sintered to form the first electrode conductive layer. Since the first electrode conductive composition has conductive particles (A), the formed first electrode conductive layer has conductivity.
Although mentioned later in detail, the 1st electrode conductive layer can be used as the connection part of the bus-bar electrode of a surface electrode with which a photovoltaic cell is equipped, or a back surface electrode, for example.
The heat treatment temperature when forming the first electrode conductive layer is not particularly limited as long as it is 400 ° C. or higher, but it is preferably 700 to 800 ° C.
Moreover, the time of the said heat processing is not specifically limited, For example, it is preferable that it is between several seconds-tens of minutes.

<Method for Producing Second Electrode Conductive Layer>
On the other hand, the manufacturing method of a 2nd electrode conductive layer is equipped with the process of heat-processing at least 150 degreeC or more and less than 400 degreeC for the 2nd electroconductive composition for electrodes mentioned above.
By the heat treatment, the second electrode conductive composition is heated to form the second electrode conductive layer. At this time, since the heat treatment temperature is relatively low, the second electrode conductive layer to be formed is formed. In the layer, the binder resin (B) remains without being completely vaporized and contributes to adhesion. The formed second electrode conductive layer has conductivity because the second electrode conductive composition contains conductive particles (A).
Similar to the first electrode conductive layer, the second electrode conductive layer can be, for example, a bus bar electrode or a back electrode connection part of the front surface electrode provided in the solar battery cell, but is not particularly suitable for high temperature treatment. It can be applied to a hybrid solar cell.
Although the heat processing temperature at the time of forming a 2nd electrode conductive layer will not be specifically limited if it is 150 to 400 degreeC, It is preferable that it is the temperature of 150-200 degreeC.
Moreover, the time of the said heat processing is not specifically limited, For example, it is preferable that it is between several seconds-tens of minutes.

[Adhesive conductive layer]
Next, the adhesive conductive layer will be described.
The adhesive conductive layer is a layer formed on the above-described first or second electrode conductive layer and formed using an adhesive conductive composition containing the binder resin (B) and the conductive particles (C). is there.
Therefore, first, the adhesive conductive composition used to form the adhesive conductive layer will be described below.

<Conductive composition for adhesion>
The conductive composition for adhesion is a composition containing a binder resin (B) and conductive particles (C).

(Binder resin (B))
The conductive composition for bonding contains a binder resin (B) from the viewpoint of adhesiveness. As this binder resin (B), what was described as binder resin (B) which the electrically conductive composition for 2nd electrodes mentioned above contains can be used preferably.

(Conductive particles (C))
The conductive composition for bonding contains conductive particles (C) from the viewpoint of conductivity.
Although it does not specifically limit as electroconductive particle (C), For example, metal powder, silver coat metal powder, etc. are mentioned. More specifically, for example, metal powders such as silver powder, nickel powder, and copper powder; silver-coated metal powders such as silver-coated nickel powder and silver-coated copper powder; and the like may be used alone. In addition, two or more kinds may be used in combination.
When using silver coat metal powder as electroconductive particle (C), the quantity (silver coat amount) of the silver which coat | covers the surface of metal powder is 5-30 mass with respect to 100 mass parts of metal powder from an electroconductive viewpoint. Part is preferable, and 20 to 30 parts by mass is more preferable.
The average particle size of the conductive particles (C) is preferably 1.5 to 20 μm for reasons such as excellent printability, and 5 to 20 μm because the specific surface area is small and is not easily oxidized during heat treatment. It is more preferable that

  It is preferable that content of electroconductive particle (C) is 1-30 mass parts with respect to 100 mass parts of binder resin (B) mentioned above, and it is more preferable that it is 5-20 mass parts.

(solvent)
In addition, the conductive composition for adhesion may contain a solvent, and for example, those described as the solvent that may contain the conductive composition for the first electrode can be suitably used.

(Method for producing conductive composition for bonding)
The method for producing the conductive composition for bonding is not particularly limited, and examples thereof include a method of mixing the above-described essential components and optional components using a ball mill or the like.

<Method for producing adhesive conductive layer>
The method for producing the adhesive conductive layer is not particularly limited as long as it is a method for forming the adhesive conductive layer using the above-described adhesive conductive composition. For example, the first or second adhesive conductive composition described above is used. A step of disposing on the electrode conductive layer.
Then, the interconnector mentioned later is arrange | positioned and binder resin (B), such as an epoxy resin which the conductive composition for adhesion contains, hardens | cures, and an adhesive conductive layer is formed. At this time, since the conductive composition for adhesion contains conductive particles (C), the adhesive conductive layer has conductivity.
In this way, the adhesive conductive layer (adhesive conductive composition) functions as a conductive adhesive, so that the first or second electrode conductive layer and the interconnector are connected.

  In addition, after an interconnector is arrange | positioned, you may leave the electrically conductive composition for adhesion | attachment for 5 to 60 second on 100-200 degreeC temperature conditions, for example.

[Interconnector]
The laminate of the present invention may further include an interconnector disposed on the above-described adhesive conductive layer. The interconnector is used when solar cells (described later) are joined in series and solar cell modules (described later).
In the present invention, as the interconnector, for example, a metal ribbon such as a copper ribbon or an aluminum ribbon can be suitably used.

  Next, based on FIGS. 1-3, the laminated body of this invention is demonstrated more concretely. In addition, below, while explaining a photovoltaic cell and a photovoltaic module, the explanation about the laminated body of this invention is also performed in the description process.

[Solar cells]
First, the structure of a photovoltaic cell is demonstrated using FIG. 1 and FIG. In FIG. 1, a solar cell is described by taking a crystalline silicon solar cell as an example. However, the solar cell is not limited to this. For example, a thin film amorphous silicon solar cell, a hybrid (HIT) solar cell Etc.

As shown in FIG. 1, the solar battery cell 10 includes a surface electrode 1 (finger electrode 1 a) on the light-receiving surface side and a pn junction silicon substrate 4 in which an n layer 3 and a p layer 5 are bonded together (hereinafter, these “ And a back surface electrode 6 (full surface electrode 6a). 1 is a schematic cross-sectional view taken along the line II of FIG.
Moreover, as shown in FIG. 1, it is preferable that the photovoltaic cell 10 comprises the anti-reflective film 2 in which the pyramid-like texture was formed for the reflectance reduction.

As shown in FIG. 2A, the solar battery cell 10 includes a finger electrode 1a and a bus bar electrode 1b as the surface electrode 1 on the light receiving surface side.
Moreover, as shown in FIG. 2B and FIG. 1, the solar battery cell 10 includes a full-surface electrode 6 a and a connection portion 6 b as the back electrode 6.

[Front electrode / Back electrode]
The arrangement (pitch), shape, height, width, etc. of the electrodes of the front electrode and the back electrode are not particularly limited.
In the embodiment shown in FIGS. 1 and 2, at least the bus bar electrode 1b in the surface electrode 1 is the above-described first or second electrode conductive layer. Similarly, the finger electrode 1a may be the first or second electrode conductive layer.
On the other hand, in the back electrode 6, it is preferable that the full surface electrode 6a is an aluminum electrode. Moreover, it is preferable that the connection part 6b is a 1st or 2nd electrode conductive layer.
Hereinafter, the case where the finger electrode 1a, the bus bar electrode 1b, and the connection portion 6b are the first or second electrode conductive layer will be described.

[Antireflection film]
The antireflection film is a film (film thickness: about 0.05 to 0.1 μm) formed on a portion of the light receiving surface where the surface electrode is not formed. For example, the silicon oxide film, the silicon nitride film, and the titanium oxide It is comprised from a film | membrane, these laminated films, etc.

[Crystal silicon substrate]
The crystalline silicon substrate is not particularly limited, and a known silicon substrate (plate thickness: about 100 to 450 μm) for forming a solar cell can be used, and it can be either a single crystal or a polycrystalline silicon substrate. May be.
The crystalline silicon substrate has a pn junction, which means that a second conductivity type light-receiving surface impurity diffusion region is formed on the surface side of the first conductivity type semiconductor substrate. When the first conductivity type is n-type, the second conductivity type is p-type. When the first conductivity type is p-type, the second conductivity type is n-type.
Here, examples of the impurity imparting p-type include boron and aluminum, and examples of the impurity imparting n-type include phosphorus and arsenic.

The method for manufacturing the solar battery cell is not particularly limited. For example, a wiring formation step of forming the wiring by applying the above-described first or second electrode conductive composition on a silicon substrate, and the obtained wiring And a heat treatment step of forming a first or second electrode conductive layer (finger electrode and bus bar electrode of the front surface electrode, and connection portion of the back surface electrode).
In the case where the solar battery cell includes an antireflection layer, the antireflection film can be formed by a known method such as a plasma CVD method.
Below, a wiring formation process and a heat treatment process are explained in full detail.

<Wiring formation process>
The wiring formation step is a step of forming a wiring by applying the first or second conductive composition for an electrode on a silicon substrate.
Here, specific examples of the coating method include inkjet, screen printing, gravure printing, offset printing, letterpress printing, and the like.

<Heat treatment process>
The heat treatment step is a step of heat-treating the wiring obtained in the wiring formation step to form the first or second electrode conductive layer.
Here, the heat treatment temperature varies depending on the first electrode conductive composition or the second electrode conductive composition, and the temperature is as described above.

[Solar cell module]
The solar cell module is a solar cell module in which solar cells are joined in series using an interconnector. Below, the structure of a solar cell module is demonstrated using FIG.

As shown in FIG. 3, the solar cell module 20 is obtained by joining solar cells 10 in series using an interconnector 8.
In the embodiment shown in FIG. 3, the interconnector 8 is a metal ribbon, and specific examples thereof include a copper ribbon and an aluminum ribbon.

  As shown in the enlarged sectional view of the joint in FIG. 3, the bus bar electrode 1b of the front electrode 1 and the interconnector 8 are bonded via an adhesive conductive layer 9, and the connecting portion 6b of the back electrode 6 and the interconnector are bonded. 8 is bonded through an adhesive conductive layer 9.

That is, in FIG. 3, the laminated body provided with the bus-bar electrode 1b or the connection part 6b, the contact bonding conductive layer 9, and the interconnector 8 optionally shows the laminated body of this invention.
In FIG. 3, the bus bar electrode 1b or the connection portion 6b and the interconnector 8 are connected using the adhesive conductive layer 9 instead of soldering, so that the interconnector 8 is bonded to the bus bar electrode 1b or the connection portion 6b. The property is excellent.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

(Examples 1-6, Comparative Example 1)
First, the components shown in Table 1 below are added to a ball mill so as to have the composition ratio shown in Table 1 below, and these are mixed to form the first or second electrode conductive composition (hereinafter referred to as “the composition ratio”). Collectively, it is also simply referred to as “conductive composition for electrodes”) and a conductive composition for adhesion.

<Interconnector adhesion>
A silicon substrate was prepared, and an aluminum paste was applied to the entire back surface by screen printing and dried.
Next, the prepared electrode conductive composition was applied to the surface of the silicon substrate by screen printing to form a predetermined wiring pattern of finger electrodes and a predetermined wiring pattern of bus bar electrodes.
After the wiring is formed by screen printing, firing is performed for 60 seconds in a firing furnace so that the peak temperature becomes the heat treatment temperature shown in Table 1 below, and the first or second electrode conductive layer (hereinafter collectively referred to simply as “heat treatment temperature”). Samples of solar cells on which bus bar electrodes (and finger electrodes) as “electrode conductive layers”) were formed were produced.

Next, the prepared conductive composition for adhesion is applied by screen printing on the bus bar electrode (electrode conductive layer) of the sample of the produced solar battery cell, and an interconnector (copper ribbon) is further disposed thereon. And left at 170 ° C. for 20 seconds.
In Comparative Example 1, the interconnector was soldered to the bus bar electrode using solder (composition: Sn-3Ag-0.5Cu).

Thereafter, according to JIS K6850: 1999, a tensile shear test was performed at a tensile speed of 50 mm / min, and the load at break (MPa) was measured.
When the load at break is 1 MPa or more, it is evaluated as “◯” as being excellent in interconnector adhesion, and when the load at break is less than 1 MPa, it is inferior to interconnector as “×”. It was evaluated. The results are shown in Table 1 below.

<Cell efficiency>
The electrical characteristics (IV characteristics) of the produced solar battery samples were evaluated using a cell tester (manufactured by Yamashita Dentsu Co., Ltd.), and the photoelectric conversion efficiency (Eff) was determined.
In Examples 1-6, since photoelectric conversion efficiency (Eff) was all 15% or more, it evaluated as "(circle)" as a thing with excellent cell efficiency. The results are shown in Table 1 below.
In Comparative Example 1, “-” was described because no evaluation was performed.

The following were used for each component in Table 1.
Silver coated nickel powder (shape: spherical, average particle size: 1.5 μm, silver coated amount: 20% by mass, manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.)
Silver powder: AgC-103 (shape: spherical, average particle size: 1.5 μm, manufactured by Fukuda Metal Foil Powder Industry)
・ Copper powder: 1200N (shape: spherical, average particle size: 2 μm, manufactured by Mitsui Mining & Smelting)

-Binder resin: The mixture obtained by mixing the following component with the following compounding quantity was used.
-Epoxy resin: 100 parts by mass of EP4100 (manufactured by Adeka)-Core shell type rubber particles: 25 parts by mass of Kane Ace MX139 (manufactured by Kaneka)-20 parts by mass of phenoxy resin: 4250 (manufactured by Mitsubishi Chemical)-Solvent: PGMEA (Showa Denko) 30 parts by mass ・ Silica: Aerosil RY200S (manufactured by Nippon Aerosil Co., Ltd.) 1 part by mass ・ Silane coupling agent: KBM-403 (manufactured by Shin-Etsu Silicone) 1 part by mass ・ Curing agent: Sun-Aid SI-60L (Sanshin Chemical) 2 parts by mass)

-Vehicle: EC-100FTP (ethyl cellulose resin solid content: 9%, manufactured by Nisshin Kasei Co., Ltd.)
Solvent: α-terpineol Solder: The same as described above was used.

As is clear from the results shown in Table 1, Examples 1 to 6 were excellent in interconnector adhesiveness. The cell performance was also excellent. Although not shown in Table 1, in Examples 1 to 6, since silver-coated nickel powder is used as a part of the conductive particles, the cost is excellent.
On the other hand, in the comparative example 1 which employ | adopted soldering, the interconnector adhesiveness was inferior.

1 surface electrode 1a finger electrode 1b bus bar electrode (first electrode conductive layer, second electrode conductive layer)
2 Antireflection film 3 n layer 4 pn junction silicon substrate 5 p layer 6 back electrode 6a full surface electrode (aluminum electrode)
6b Connection portion (first electrode conductive layer, second electrode conductive layer)
7 Crystalline silicon substrate 8 Interconnector 9 Adhesive conductive layer 10 Solar cell 20 Solar cell module

Claims (9)

A first electrode formed by heat-treating a conductive composition for a first electrode containing conductive particles (A) in which 25 to 100% by mass is silver-coated metal powder (a) at a temperature of 400 ° C. or higher. A conductive layer;
An adhesive conductive layer disposed on the first electrode conductive layer and formed using an adhesive conductive composition containing a binder resin (B) and conductive particles (C);
A laminate comprising: A second electrode conductive composition containing conductive particles (A) in which 25 to 100% by mass is silver-coated metal powder (a) and binder resin (B) is heat-treated at a temperature of 150 ° C. or higher and lower than 400 ° C. A second electrode conductive layer formed by:
An adhesive conductive layer disposed on the second electrode conductive layer and formed using an adhesive conductive composition containing the binder resin (B) and conductive particles (C);
A laminate comprising:   The laminated body of Claim 1 or 2 whose average particle diameter of the said silver coat metal powder (a) is 1.5-20 micrometers.   The laminated body in any one of Claims 1-3 whose said silver coat metal powder (a) is silver coat nickel powder which has 5-30 mass parts silver coat with respect to 100 mass parts of nickel powder.   The laminate according to any one of claims 1 to 4, wherein the conductive particles (A) other than the silver-coated metal powder (a) are silver powder.   The said electroconductive particle (C) is at least 1 sort (s) chosen from the group which consists of silver powder, nickel powder, copper powder, silver coat nickel powder, and silver coat copper powder in any one of Claims 1-5. Laminated body.   The laminated body in any one of Claims 1-6 whose average particle diameter of the said electroconductive particle (C) is 1.5-20 micrometers.   The laminated body in any one of Claims 1-7 in which the said binder resin (B) contains at least 1 sort (s) chosen from the group which consists of an epoxy resin, a polyester resin, a urethane resin, a phenol resin, and a polyimide resin.   Furthermore, the laminated body in any one of Claims 1-8 provided with the interconnector arrange | positioned on the said adhesive conductive layer.