JP2022155933A - conductive adhesive composition - Google Patents

Abstract

To provide a conductive adhesive composition comprising a conductive powder and a curable component which can achieve good conductivity and good adhesiveness and good maintenance of a thickness of an adhesive layer.SOLUTION: There is provided a conductive adhesive composition which comprises (A) a curable component which is a conductive powder and a silicone compound and (D) spacer particles, wherein the content of the curable component is 10 mass% or more when the total mass of the conductive adhesive composition is defined as 100 mass%. In the curable component, (B) a curable component 1 is a radically polymerizable silicone monomer and (C) a curable component 2 is an addition curing reactive silicone resin which is cured within a temperature range of 100°C to 200°C. The spacer particles (D) are at least any of glass particles, ceramic particles, organic resin particles excluding acryl particles or silicone particles which have an average particle diameter (median particle) larger than the conductive powder (A) and when the total volume of the curable components is defined as 100 vol%, the content is 0.1 vol% or more and 10.0 vol% or less.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a conductive adhesive composition, and more particularly to a conductive adhesive composition capable of maintaining a thickness between adherends to be adhered.

BACKGROUND ART Electrically Conductive Adhesives (ECA) have been widely used in the fields of electrical equipment, electronic equipment, and the like in recent years. A conductive adhesive is basically composed of a conductive powder and a curable component, and by appropriately selecting the type or composition of the curable component, various adherends can be adhered in a conductive manner. The conductivity can be adjusted by appropriately selecting the type of the conductive powder.

For example, Patent Document 1 describes a conductive adhesive using at least one resin component (curable component) and micron-sized and submicron-sized conductive particles (conductive powder). Curable components include thermosetting resins which may be liquid at 22°C or which may melt and become liquid at relatively low temperatures such as 100°C or less. Moreover, it is described that not only thermosetting resin but also thermoplastic resin can be used as the resin component.

Japanese Patent Publication No. 2013-541611

A conductive adhesive is required to have both adhesiveness and conductivity after curing. Patent document 1 also mentions the strength of the adhesive as one of the problems of the conductive adhesive. However, in Patent Document 1, regarding the conductivity of the conductive adhesive, it is described that the contribution of the conductive particles (conductive powder) is large, but the curable component or the resin component affects the conductivity. There is no particular mention of

Moreover, depending on the composition of the conductive adhesive, there is a possibility that the thickness of the conductive adhesive (thickness of the adhesive layer) formed between the adherends cannot be properly maintained. If the thickness of the adhesive layer cannot be sufficiently maintained in a state in which the adherends are electrically conductively adhered to each other by the conductive adhesive, the distance between the adherends cannot be appropriately maintained. In such a case, long-term reliability may be affected in a device including an adherend, such as an electric device or an electronic device.

The present invention has been made to solve such problems, and achieves both good conductivity and good adhesion in a conductive adhesive composition containing a conductive powder and a curable component. It is also an object of the present invention to enable the thickness of the adhesive layer to be maintained satisfactorily.

In order to solve the above problems, the conductive adhesive composition according to the present invention contains (A) a conductive powder and a curable component that is a silicone compound, and when the total mass is 100% by mass, The content of the curable component is 10% by mass or more, and the curable components include at least (B) a radically polymerizable silicone monomer that is curable component 1, and (C) 100 that is curable component 2. An addition-curable reactive silicone resin that cures within the range of ° C. to 200 ° C. is used, and further contains (D) spacer particles having a larger average particle size (median size) than the (A) conductive powder, The spacer particles (D) are at least one of glass particles, ceramic particles, organic resin particles excluding acrylic particles, or silicone particles. (D) The content of the spacer particles is 0.1% by volume or more and 10.0% by volume or less.

According to the above configuration, by using both the radically polymerizable silicone monomer and the addition-curable reactive silicone resin as the curable components, it is possible to achieve good electrical conductivity and good adhesive strength. Moreover, since at least one of glass particles, ceramic particles, and silicone particles is contained as spacer particles, the cured adhesive layer can achieve a good thickness when the conductive adhesive composition is cured. can.

Therefore, even in an environment where a thermal cycle in which high temperatures and low temperatures are repeated occurs, it is possible to adhere the adherends to each other satisfactorily while ensuring good electrical connectivity between the adherends. Moreover, since the spacer particles also provide stress relaxation, the adhesive strength can be further improved. Therefore, in a conductive adhesive composition containing a conductive powder and a curable component, it is desirable to achieve both good conductivity and good adhesion, and to maintain the thickness of the adhesive layer satisfactorily. becomes possible.

In the conductive adhesive composition having the above configuration, the spacer particles (D) may be silicone particles.

Further, in the electrically conductive adhesive composition having the above structure, a monofunctional monomer and a bifunctional monomer may be used in combination as the (B) radically polymerizable silicone monomer, which is the curable component 1. .

Further, in the conductive adhesive composition having the above configuration, the average particle diameter (median diameter) of the (D) spacer particles is in the range of 10 to 60 μm, and the CV value (Coefficient of Variation) is 30% or less.

Further, in the conductive adhesive composition having the above structure, the (A) conductive powder is a metal powder composed of at least one metal selected from the group consisting of Ag, Cu, Ni, Al, and Pd. , an alloy powder containing one or more metals selected from the group, or a coated powder having a surface coated with one or more metals selected from the group.

In addition, the conductive adhesive composition having the above-described configuration may be configured so as to be applied onto a base material by a printer or a dispenser.

In addition, the conductive adhesive composition having the above configuration may be configured to be used for adhesion of solar cells constituting a solar cell module.

In the present invention, with the above configuration, in a conductive adhesive composition containing a conductive powder and a curable component, both good conductivity and good adhesion are achieved, and the thickness of the adhesive layer is improved. There is an effect that it can be maintained at

(A) is a schematic side view showing the configuration of a solar cell module, which is an example to which the conductive adhesive composition according to the present disclosure is applied, and (B) is a conventional general solar cell module. It is a typical side view which shows a structure. 4 is a graph showing changes in adhesive strength retention in a heat cycle test when the content of spacer particles is varied in an example of a conductive adhesive composition according to the present disclosure.

An example of preferred embodiments of the present disclosure will be specifically described below. The conductive adhesive composition according to the present disclosure contains (A) a curable component that is a conductive powder and a silicone compound, and the content of the curable component is 10% by mass when the total mass is 100% by mass. % or more, and as curable components, at least (B) a radically polymerizable silicone monomer that is curable component 1, and (C) an addition that cures within the range of 100 ° C. to 200 ° C. that is curable component 2 Curable reactive silicone resins are used. Furthermore, the conductive adhesive composition according to the present disclosure contains (D) spacer particles having a larger average particle size (median size) than (A) the conductive powder, and the (D) spacer particles are glass particles. , ceramic particles, organic resin particles other than acrylic particles, or silicone particles. The content of the spacer particles (D) is 0.1% by volume or more and 10.0% by volume or less when the total volume of the curable components is 100% by volume.

In the conductive adhesive composition according to the present disclosure, as described later, (D) the spacer particles may be silicone particles, and (B) the radically polymerizable silicone monomer, which is the curable component 1, A monofunctional monomer and a bifunctional monomer may be used in combination.

[(A) Conductive powder]
The (A) conductive powder contained in the conductive adhesive composition according to the present disclosure is not particularly limited as long as it is a powder (particles) having conductivity. Although the material is not particularly limited, a relatively low-resistance conductive material can be mentioned from the viewpoint of realizing good conductivity. Specifically, for example, one or more metals selected from the group of silver (Ag), copper (Cu), nickel (Ni), aluminum (Al), and palladium (Pd) can be used. Among these, silver (Ag) can be preferably used.

(A) The specific material composition of the conductive powder is not particularly limited, and the powder (metal powder) substantially composed of one type of metal (or conductive material), the alloy composed of multiple types of metals Examples include powders, composite material powders composed of metal and non-metal, and the like. Among these, the alloy powder may contain at least one metal selected from the above group among a plurality of metals. Therefore, the alloy powder may be composed of one or more metals selected from the group and metals not included in the group, or may be composed of two or more metals included in the group. .

Examples of composite material powders include coated powders in which the surfaces of non-metallic powders or relatively high-resistance metal powders are coated with relatively low-resistance metals. In this coated powder, the relatively low-resistance metal may be one or more metals selected from the group described above. That is, if a nonmetallic powder or a metal powder having a relatively high resistance is defined as a "base powder", the surface of the base powder is coated with one or more metals selected from the above group. Any powder may be used. The low-resistance metal to be coated may be one of the above groups, or may be an alloy of two or more.

(A) When silver (Ag) is used as the material of the conductive powder, for example, silver powder, silver alloy powder, silver-coated copper powder, silver-coated nickel powder, silver-coated aluminum powder, silver-coated glass powder, etc. can be mentioned. That is, in the present disclosure, at least one of silver powder, silver alloy powder, and silver-coated powder can be mentioned as a preferable example of (A) the conductive powder.

(A) The shape of the conductive powder is also not particularly limited, and various shapes can be selected and used. Typical examples include substantially spherical powders (spherical powders), flaky powders (flaky powders), dendritic powders, and the like. It is preferable to use a combination of spherical powder and flaky powder, although it depends on various conditions such as the specific composition, specific application, and specific physical properties of the conductive adhesive composition. By using a combination of powders having different shapes in this way, it is possible to satisfactorily fill (A) the conductive powder after curing the curable component.

It should be noted that the flaky powder in the present disclosure may be powder having a shape similar to a flat plate or a thin rectangular parallelepiped when viewed as a whole, even if it is partially uneven and deformed. In addition, the flake shape can be rephrased as a flaky shape or a scaly shape. In addition, the spherical powder in the present disclosure may be powder that has a three-dimensional shape that is closer to a cube than a rectangular parallelepiped when viewed as a whole, even if it is partially uneven and deformed. In addition, spherical shape can be rephrased as granular shape.

(A) The specific physical properties of the conductive powder are not particularly limited, and the average particle size, specific surface area, tap density, etc. may be within known ranges. Of these, the average particle diameter (median diameter) is, for example, in the range of 0.1 to 10 μm when (A) the conductive powder is spherical, and (A) the conductive powder is flaky powder. If there is, it can be, for example, within the range of 2 to 20 μm. Further, the BET specific surface area can be, for example, in the range of 0.5 to 2.0 m ² /g if (A) the conductive powder is spherical, and (A) if the conductive powder is flaky powder, If there is, it can be, for example, within the range of 0.1 to 5.0 m ² /g.

The conductive adhesive composition according to the present disclosure contains (D) spacer particles in addition to the basic components (A) conductive powder and curable component. (A) The average particle size of the conductive powder should be relatively smaller than the average particle size of the (D) spacer particles. The method for measuring the average particle size of (A) the conductive powder and (D) the spacer particles is not particularly limited, and in the present disclosure, a method of measuring using a particle size distribution measuring apparatus as described in the examples below is adopted. is doing. Also, the method for evaluating the BET specific surface area is not particularly limited, and it may be measured and evaluated by the one-point BET method by nitrogen adsorption using a known specific surface area meter.

(A) When the conductive powder is a coated powder, the coating amount of the conductive material (metals such as Ag, Cu, Ni, Al and Pd constituting the above group) to be coated is not particularly limited. When the mass of the original powder not coated with the conductive material is 100% by mass, the coating amount of the conductive material may be, for example, in the range of 5 to 30% by mass, and 6 to 25% by mass. may be within the range of 7.5 to 20% by mass.

In the conductive adhesive composition according to the present disclosure, as (A) the conductive powder, only one type of powder may be used, or two or more types of powders may be used in combination as appropriate. The type of conductive powder (A) used here includes not only differences in material and shape (spherical or flaky), but also differences in average particle size. In the examples to be described later, as the (A) conductive powder, a combination of spherical silver powder (silver powder 1, abbreviation A1) and flaky silver powder (silver powder 2, abbreviation A2 or silver powder 3, abbreviation A3) will be given. (see Table 1).

In addition, in the conductive adhesive composition according to the present disclosure, one or more metals selected from the above group, that is, "other conductive powder ” may be used together as (A) the conductive powder. Examples of such "other conductive powder" include gold powder, lead powder, carbon powder, and the like.

(A) The method for producing the conductive powder is not particularly limited, and a known method can be used. Examples of spherical powders include powders produced by a wet reduction method, and spherical powders produced by other known methods such as an electrolysis method and an atomization method, but are not particularly limited. Alternatively, in the case of flaky powder, flaky powder can be produced by using a spherical powder produced by a known method as a base powder and subjecting the base powder to a known mechanical treatment. The physical properties such as the particle size and the degree of cohesion of the base powder are determined according to the purpose of use of the conductive adhesive composition (types of electrodes, wiring, etc., or types of electronic components or electronic devices equipped with these electrodes, wiring, etc.). It can be selected as appropriate.

[Curable component]
The curable component contained in the conductive adhesive composition according to the present disclosure functions as a curable binder that enables electrical connection between the (A) conductive powders by curing and adheres to the adherend. be. In the present disclosure, (B) curable component 1 and (C) curable component 2, both of which are silicone compounds, are used as such curable components.

(B) Curable component 1 is not particularly limited as long as it is a radically polymerizable silicone monomer. For example, monomers having a skeleton structure such as silane, silicone oligomer, silicone resin, organosiloxane, diorganosiloxane, organopolysiloxane, and diorganopolysiloxane, and the skeleton structure has one or more radical-reactive functional groups. Configuration can be mentioned.

Typically, a monofunctional monomer having a radical reactive functional group only at one end of a polysiloxane structure (-[Si( _CH3 ) ₂ -O] _n- ; n is an arbitrary integer) (the other end is optionally substituted groups), bifunctional monomers having radically reactive functional groups at both ends of the polysiloxane structure, and polyfunctional monomers having three or more radically reactive functional groups in the polysiloxane structure. The polysiloxane structure may contain arbitrary substituents, and the polysiloxane structure may contain side chains and the like. A specific type of the radical-reactive functional group is not particularly limited, but typical examples include an acrylic group or a methacrylic group.

Here, as the radically polymerizable silicone monomer (B) curable component 1, it is preferable to use a monofunctional monomer and a bifunctional monomer in combination. This makes it easier to achieve both good conductivity (electrical connectivity) and adhesion in the resulting conductive adhesive composition. Here, the functional group equivalent weight of (B) curable component 1 is not particularly limited, but the functional group equivalent weight of the monofunctional monomer is preferably 1000 g/mol or less.

In the obtained conductive adhesive composition, the functional group equivalent of the monofunctional monomer tends to affect the electrical conductivity and adhesiveness rather than the functional group equivalent of the bifunctional monomer. When the functional group equivalent weight of the monofunctional monomer is 1000 g/mol or less, it becomes possible to achieve good electrical conductivity and adhesiveness without affecting the functional group equivalent weight of the bifunctional monomer. Although this point is not described in detail, it has been experimentally verified.

The functional group equivalent weight of the radically polymerizable silicone monomer can be calculated by a known method. For example, the molecular weight of one main structure (for example, siloxane structure) of the silicone monomer is multiplied by the ratio (X1/X2) of the number X1 of the main structure and the number X2 of the reactive functional groups to obtain one reactive functional group. The functional group equivalent (g/mol) can be calculated by obtaining the mass of the main structure per molecule and converting that mass into the number per mole (multiplied by Avogadro's number). When a commercially available product is used as the radically polymerizable silicone monomer, it may be based on the functional group equivalent described in the specifications of the commercially available product.

As the radically polymerizable silicone monomer used as (B) curable component 1 in the present disclosure, a single monomer compound may be used, or two or more monomer compounds may be used in combination. This point is the same for monofunctional monomers or bifunctional monomers, and as monofunctional monomers or bifunctional monomers, only one type may be used, or two or more types may be used.

(B) The molecular weight or material of the radically polymerizable silicone monomer used as the curable component 1 is not particularly limited, and any molecular weight or material may be used as long as it does not affect the physical properties of the conductive adhesive composition or its cured product. A material having physical properties may be used. Here, (B) curable component 1: radically polymerizable silicone monomer preferably has a curing initiation point of 100° C. or lower.

In the conductive adhesive composition according to the present disclosure, (B) curable component 1 is used to enable short-time curing at a curing temperature of at least 150° C., according to the results of Examples described later. It becomes a curable component that can be used. Therefore, by using one having a curing starting point of 100° C. or less, it becomes easy to achieve good curing at a curing temperature of 150° C. in a short time.

A radical polymerization initiator that initiates the polymerization reaction of the radically polymerizable silicone monomer can be used in the conductive adhesive composition according to the present disclosure. This radical polymerization initiator may be contained in advance as a component of the conductive adhesive composition, or may be added separately during the polymerization reaction. Specific radical polymerization initiators are not particularly limited, but typically include organic peroxides or azo initiators.

Representative organic peroxides include t-butyl peroxy-2-ethylhexanoate, t-hexyl peroxyisopropyl monocarbonate, t-butyl peroxybenzoate, t-butyl peroxyneodecanoate, t -Peroxyesters such as butyl peroxylaurate, t-butyl cumyl peroxide, t-butyl peroxyacetate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate; methyl ethyl ketone peroxide; ketone peroxides such as; hydroperoxides such as 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, and p-menthane hydroperoxide; alkyl peroxides such as di-t-butyl peroxide; oxide; and the like.

Further, typical azo initiators include 2,2′-azobisisobutyronitrile, 2,2′-azobis(2-methylbutyronitrile), 2,2′-azobis(2,4- dimethylvaleronitrile), 1,1'-azobis-1-cyclohexanecarbonitrile, dimethyl-2,2'-azobisisobutyrate, 2-(carbamoylazo)isobutyronitrile, 2-phenylazo-4-methoxy- 2,4-dimethylvaleronitrile, azodi-t-octane, azodi-t-butane and the like.

These polymerization initiators may be used alone or in combination of two or more. Also, the amount of polymerization initiator to be used, the conditions of use, etc. are not particularly limited, and a known amount of use or conditions of use may be used. In the present disclosure, organic peroxides can be mentioned as more preferred radical polymerization initiators. In the examples described later, t-butylperoxy-2-ethylhexanoate is used as the polymerization initiator (see Table 4).

(C) Curable component 2 is not particularly limited as long as it is an addition curing reactive silicone resin that cures within the range of 100°C to 200°C. Examples of specific silicone resins include known thermosetting silicone resins.

Typical thermosetting silicone resins include, for example, silanes, silicone oligomers, silicone resins, organosiloxanes, diorganosiloxanes, organopolysiloxanes, diorganopolysiloxanes, and the like. Configurations having the above reactive functional groups can be mentioned. The skeleton structure may be a linear structure or may have a branched chain.

As described above, (B) curable component 1: radically polymerizable silicone monomer is a curable component for realizing short-time curing at 150° C., but (C) curable component 2: addition curing reactive silicone The resin can be said to be a curable component for improving adhesive strength and achieving adhesion to adherends.

(C) Curable Component 2: Addition-curing reactive silicone resins include thermosetting silicone resins as described above, but particularly preferably silicone resins having double bonds, that is, reactive functional A silicone resin having a vinyl group can be exemplified. Here, since the vinyl radical also has radical polymerizability, it can be considered that the addition curing reactive silicone resin also has radical polymerizability.

However, when viewed as a radically reactive compound, vinyl radicals have a relatively slow reaction rate compared to acrylate or methacrylate radicals. In the present disclosure, it can be determined that this difference in reaction rate is the difference between (B) curable component 1 and (C) curable component 2.

In the present disclosure, (B) curable component 1: radically polymerizable silicone monomer typically includes an acrylic group-containing silicone compound or a methacrylic group-containing silicone compound, and (C) curable component 2: addition curing Typical examples of reactive silicone resins include vinyl group-containing silicone resins (which may include not only polymers but also prepolymers and the like). It is not limited to this representative example, and any combination of reactive silicone compounds having different reaction rates, and a combination of a monomer compound ((B) curable component 1) and a polymer compound ((C) curable component 2) good.

The thermosetting silicone resin used as (C) curable component 2 in the present disclosure may have a single type of skeletal structure and a single type of reactive functional group, or may have multiple types of skeletal structures and multiple types of reactive functional groups. It may also have a reactive functional group of some kind. In addition, as described above, one or more reactive functional groups may be contained in one skeleton structure. In other words, one molecule of silicone resin (having an arbitrary skeleton structure) has at least one reactive It is sufficient if it has a functional group. In addition, the reactive functional group may be at the terminal of the skeleton structure, may be at the side chain, or may be at either the terminal or the side chain.

(C) As the addition curing reactive silicone resin of the curable component 2, by using one having a curing temperature within the range of 100 to 200 ° C., the obtained conductive adhesive composition has good conductivity (adhesion It is possible not only to realize electrical connectivity between bodies) and good adhesive strength, but also to cure the conductive adhesive composition in a relatively short time. Therefore, it becomes possible to achieve not only better adhesion but also more efficient curing.

As described above, (B) curable component 1 is preferably a radically polymerizable silicone monomer having a curing initiation point of 100° C. or less for efficient curing at a curing temperature of 150° C. From this point of view, as (C) curable component 2, it is better to use an addition curing reactive silicone resin that cures at less than 100 ° C. Curing of (B) curable component 1 and (C) curable component 2 It is considered preferable because the temperature can coexist.

However, as shown in the results of Examples described later, when an addition reaction-curable silicone resin having a curing temperature of less than 100° C. is used, the resulting conductive adhesive composition has both good conductivity and adhesion. It became clear that it could not be realized (see Reference Examples 1 to 6). Addition reaction curable silicone resins with curing temperatures below 100° C. resulted in poor conductivity and adhesion rather than poor conductivity alone or poor adhesion alone. .

On the other hand, if an addition-curing reactive silicone resin that cures within the range of 100 to 200° C. is used as the (C) curable component 2, the resulting conductive adhesive composition will be electrically conductive even though the curing temperature differs. It was found that a good balance between toughness and adhesiveness can be obtained. If the curing temperature exceeds 200°C as the addition curing reactive silicone resin, it may not be sufficiently cured at the curing temperature of 150°C when curing the curable component 1 (B).

In the conductive adhesive composition according to the present disclosure, various catalysts can be used to accelerate the addition curing reaction of the addition curing reactive silicone resin, which is the curable component 2 (C). This addition curing reaction catalyst may be contained in advance as a component of the conductive adhesive composition, or may be added and mixed separately during the polymerization reaction. A specific addition curing reaction catalyst is not particularly limited, and a compound having a suitable catalytic action can be appropriately used according to the type of the addition curing reactive silicone resin.

For example, in Examples to be described later, an addition-curable silicone resin in which a silicone polymer having a vinyl group and an H group is cured by a hydrosilylation reaction in the presence of a catalyst is used as (C) the curable component 2. This silicone resin can use a metal chelate compound as an addition curing reaction catalyst. In the examples described later, aluminum monoacetylacetonate bis(ethylacetoacetate), which is an aluminum-based chelate compound, is used as the addition curing reaction catalyst, but the addition curing reaction catalyst is not limited to this. Alternatively, in the case of a two-component liquid silicone rubber that requires heat curing, a main agent containing a silicone compound as a main component and a curing agent are mixed in advance and cured, so a curing agent suitable for the main agent may be used.

When (B) curable component 1 and (C) curable component 2 are used in combination as curable components, the compounding ratio thereof is not particularly limited. As will be explained later in the examples, unless the curable component is only (B) curable component 1 or (C) only curable component 2, even if the blending ratio of these two components is changed, it can be obtained In any conductive adhesive composition, both good conductivity and good adhesive strength can be achieved (see Reference Examples 1 to 5).

Based on the results of Reference Examples 1 to 5, a preferred example of the compounding ratio of (B) curable component 1 and (C) curable component 2 is, for example, component (B)/component (C) = 90/ The range of 10 to 10/90 (mass ratio) can be mentioned, and the range of (B) component / (C) component = 80/20 to 20/80 (mass ratio) can be mentioned, or Component (B)/component (C) can be in the range of 75/25 to 25/75 (mass ratio).

Moreover, when a radical initiator or an addition curing reaction catalyst is used, the content of these components is not particularly limited. Depending on the specific type of (B) curable component 1 or (C) curable component 2 used, the specific type of radical initiator or addition curing reaction catalyst used, or other conditions, known suitable content (blended amount or added amount) can be used.

As the curable component, in addition to (B) curable component 1: radical polymerizable silicone monomer and (C) curable component 2: addition curing reactive silicone resin, other curable components may be contained. . Such other curable components may be compounds that do not interfere with both good electrical conductivity and good adhesive strength in the conductive adhesive composition to be obtained. In addition, the content of the other curable component is not particularly limited, and is to the extent that the effect expected by containing the other curable component is obtained without hindering the effect of the resulting conductive adhesive composition. should be contained in the amount of

[(D) Spacer particles]
The conductive adhesive composition according to the present disclosure includes (A) the conductive powder and two types of curable components (B) curable component 1: radically polymerizable silicone monomer and (C) curable component 2 described above. : Contains an addition-curable reactive silicone resin as a basic component, and further contains (D) spacer particles. The (D) spacer particles are silicone-based particles composed of a silicone compound, and have a larger average particle diameter (median diameter) than the (A) conductive powder.

Although the average particle diameter (median diameter) of the spacer particles (D) is not particularly limited, as described above, when the conductive powder (A) is a spherical powder, the preferred average particle diameter is in the range of 0.1 to 10 μm. Therefore, the average particle diameter of the spacer particles (D) may be in the range of 10 to 60 μm (or may be more than 10 μm and 60 μm or less). Further, (A) when the conductive powder is flaky powder, the preferred average particle size is in the range of 2 to 20 μm, so (D) the average particle size of the spacer particles is in the range of 20 to 60 μm. (Alternatively, it may be more than 20 μm and 60 μm or less).

When the conductive adhesive composition is cured to form a cured adhesive layer that electrically bonds the adherends together, depending on the specific thickness required for the cured adhesive layer, (D) The lower limit of the average particle size of spacer particles may be 30 μm or more. Therefore, the lower limit of the average particle size of the spacer particles (D) can be appropriately set according to the average particle size of the conductive powder (A) used in combination.

On the other hand, the upper limit of the average particle diameter of the (D) spacer particles is preferably 60 µm or less. (D) If the average particle size of the spacer particles exceeds 60 μm, the adhesive strength of the cured adhesive layer, which is a cured product of the conductive adhesive composition, tends to decrease. The method for measuring the average particle size of the (D) spacer particles is not particularly limited, and in the present disclosure, similarly to the average particle size of the (A) conductive powder, the particle size distribution is as described in the examples below. A method of measuring using a measuring device is adopted.

The material of the spacer particles (D) is not particularly limited as long as it has shape stability such that the cured adhesive layer can achieve a sufficient thickness even after the conductive adhesive composition is cured. However, from the results of Examples described later, it has become clear that at least acrylic resin is not desirable as the material for the (D) spacer particles from the viewpoint of adhesive strength. This is because the curable component (resin component) of the conductive adhesive composition according to the present disclosure is a silicone compound (silicone-based material). It is conceivable that the adhesive strength may be affected.

(D) Spacer particles are typically made of glass; zirconia (ZrO ₂ ), alumina (Al ₂ O ₃ ), silica (SiO ₂ ), silicon carbide (SiC), silicon nitride (Si ₃ N ₄ ) and other ceramics; acrylic resins, nylon resins, phenol resins, silicone resins, urethane resins, epoxy resins and other resins; See Comparative Examples 2-7).

On the other hand, the silicone resin is a material of the same type as (B) curable component 1: radical polymerizable silicone monomer and (C) curable component 2: addition curing reactive silicone resin, which are curable components (resin components). Therefore, the (D) spacer particles made of silicone resin are considered to have good affinity with the curable component. In fact, in the examples described later, when silicone particles were used as the (D) spacer particles, good adhesive strength was achieved.

On the other hand, in Examples to be described later, even when glass particles are used, good adhesive strength can be achieved. In addition, the ceramic particles composed of the ceramics described above can also achieve the same good adhesive strength as the glass particles, and resin particles other than acrylic particles can also achieve practically good adhesive strength. .

Therefore, in the present disclosure, the (D) spacer particles may be particles composed of a material other than acrylic particles, but preferably include glass particles, ceramic particles, and resin particles other than acrylic particles. A particularly preferred example is silicone particles. Alternatively, if the silicone particles (D) spacer particles are silicone particles, the resulting conductive adhesive composition (cured adhesive layer) can achieve not only good thickness and good adhesive strength, but also good conductivity. can do.

Here, nylon resin, phenol resin, urethane resin, epoxy resin (and unsuitable acrylic particles), etc., exemplified as the material of the (D) spacer particles, are all mainly composed of the main skeleton of the resin (polymer/polymer). In contrast to carbon, silicone resin (silicon resin) has silicon as the main skeleton. Therefore, in the present disclosure, resins in which the main skeleton is composed of carbon are included as organic resins, and are distinguished from silicone resins. Therefore, the (D) spacer particles in the present disclosure may be glass particles, ceramic particles, organic resin particles other than acrylic particles, or silicone particles.

The specific configuration of the (D) spacer particles is not particularly limited, and may be particles composed of a single type of material or particles composed of two or more types of materials. (D) When the spacer particles are composed of two or more kinds of materials, the plurality of materials may be of the same type or may be of different types. For example, although silver-coated glass particles are used in Examples described later, composite particles in which the surfaces of glass particles are coated with a different material may be used.

Alternatively, composite silicone spherical particles are used as the silicone particles in the examples described later. The composite silicone spherical particles are rubber-like silicone spherical particles coated with a silicone resin on their surfaces, and are composite particles made of the same material. In the examples described later, rubber-like silicone spherical particles themselves are used instead of composite particles. It can be material.

Alternatively, particles composed of a plurality of silicone resins or silicone compounds may be used as the silicone particles. In other words, the composite particles may be of a type in which a plurality of materials are used for the particle body instead of the type of composite particles that coat the surface. This point is the same for glass particles or ceramic particles. Incidentally, the material constituting the spacer particles (D) may contain various known additives.

Like the silver-coated glass particles described above, when the surface of the base material particles is coated with a metal material, the conductivity of the cured adhesive layer in the conductive adhesive composition according to the present disclosure may be improved in some cases. . Examples of such metal materials include gold, silver, copper, and alloys thereof, which are excellent in electrical conductivity. (D) The coating amount (coating amount) of the metal material coated on the surface of the spacer particles is not particularly limited. It can be appropriately set according to various conditions such as influence on shape stability.

As the (D) spacer particles, only one type may be used, but different types of particles may be used in combination as appropriate. For example, a plurality of types of particles may be used as silicone particles, silicone particles and glass particles, ceramic particles, or organic resin particles other than acrylic particles may be used in combination, or glass particles and metal-coated glass particles may be used together. may be used together.

(D) Spacer particles may be spherical in shape. Although it is possible to adopt a shape other than a spherical shape, a spherical shape is preferable from the viewpoint of more stably achieving the thickness of the cured adhesive layer. If the shape is other than spherical, the (D) spacer particles have a longitudinal direction, and the thickness of the layer may vary depending on the direction of the (D) spacer particles in the cured adhesive layer.

Other physical properties of the (D) spacer particles are not particularly limited, but the CV value (Coefficient of Variation) of the (D) spacer particles is preferably 30% or less. The CV value is an index showing the dispersion of the particle size distribution of particles, and it can be judged that the smaller the value, the less the dispersion of the particle size distribution and the higher the uniformity. When the CV value of the (D) spacer particles exceeds 30%, the variation in the particle size distribution of the (D) spacer particles increases, and the shape retention of the conductive adhesive composition may deteriorate. In this case, the cured adhesive layer may spread more than expected or the thickness of the cured adhesive layer may not be sufficiently secured. In addition, the evaluation method of the CV value is not particularly limited, either, and in the present disclosure, evaluation is performed by the method described in Examples described later.

[Production and Use of Conductive Adhesive Composition]
The method for producing the conductive adhesive composition according to the present disclosure is not particularly limited, and methods known in the field of conductive adhesive compositions can be suitably used. As a representative example, there is a method of blending each component described above in a predetermined blending ratio (based on mass) and forming a paste using a known kneading device. Examples of the kneading device include a three-roll mill.

In the conductive adhesive composition according to the present disclosure, the blending amount (content) of (A) the conductive powder is not particularly limited as long as it is within a conventionally known range. Specifically, for example, the conductive adhesive composition according to the present disclosure is based on (A) conductive powder and two types of curable components ((B) curable component 1 and (C) curable component 2). The content (blended amount) of this basic component is the lower limit of the total content of the two curable components when the total mass of the conductive adhesive composition is 100% by mass. may be 10% by mass or more, may be 15% by mass or more, may be 20% by mass or more, may be 25% by mass or more, or may be 30% by mass or more. good too.

If the total content of the two types of curable components is less than 10% by mass, the content of the curable components in the conductive adhesive composition becomes too small relative to (A) the conductive powder, Adhesion of the conductive adhesive composition may be affected. On the other hand, the upper limit of the total content of the two types of curable components is not particularly limited. can be set to a large amount.

The content of (A) the conductive powder is also not particularly limited. % or more and may be 60% by mass or more. Moreover, the upper limit of the content of (A) the conductive powder may be 90% by mass or less, and may be 85% by mass or less. (A) If the content of the conductive powder is within this range, both good conductivity (electrical connectivity of the adherend) and good adhesion (adhesion strength) can be achieved.

Note that the upper and lower limits of the content of (A) the conductive powder and the lower limits of the content of the two types of curable components are in Examples (Example 2, Examples 4 to 7) described later. It is a numerical value that can be reasonably derived from the results and the knowledge of the technical field of conductive adhesives.

In the conductive adhesive composition according to the present disclosure, if necessary, in addition to the basic components ((A) conductive powder and two types of curable components) described above, known in the field of conductive adhesive compositions may contain various additives. The additive is not particularly limited, but specific examples include solvents, leveling agents, antioxidants, ultraviolet absorbers, silane coupling agents, antifoaming agents, viscosity modifiers, extenders, and the like. can. These additives can be added as long as they do not interfere with the effects of the present disclosure.

In the present disclosure, the conductive adhesive composition may contain at least (A) a conductive powder, (B) a curable component 1 and (C) a curable component 2. Ingredients can be defined as "other ingredients" as exemplified in the examples below. The components (A), (B), (C), and other components may all be commercially available products, which may contain various additive components. When a commercial product is used as components (A) to (C) and the commercial product contains an additive component, the additive component can be classified as "other components". Although commercial products are basically used for each component in the examples described later, if necessary, specially manufactured or prepared products may be used instead of commercial products.

In addition, the conductive adhesive composition according to the present disclosure contains (A) a conductive powder, (B) a curable component 1 and (C) a curable component 2 as basic components, and further contains (D) spacer particles. However, the content (blended amount) of the spacer particles (D) is such that the content of the spacer particles (D) is 0.1% by volume or more when the total volume of the curable components is 100% by volume. It may be within the range of 10.0% by volume or less (0.1 to 10.0% by volume).

The method for measuring or evaluating the volume of the curable components ((B) curable component 1 and (C) curable component 2) in the present disclosure is not particularly limited, and known techniques can be suitably used. In the present embodiment and examples described later, the volume is calculated from the density of the substance (compound) that constitutes the curable component ((B) curable component 1 and (C) curable component 2), and thereby (D ) to obtain the volume fraction of spacer particles.

If the content of the (D) spacer particles is less than 0.1% by volume, there is a possibility that the effect of adding the (D) spacer particles may not be sufficiently obtained. Further, if the content of the (D) spacer particles exceeds 10.0% by volume, not only is it impossible to obtain the effects commensurate with the content of the (D) spacer particles, but the amount of the (D) spacer particles becomes too large, resulting in adhesion of the cured adhesive layer. Strength may decrease.

The method for forming a pattern to be a cured adhesive layer using the conductive adhesive composition according to the present disclosure is not particularly limited, and various known forming methods can be suitably used. A typical example is screen printing, as shown in Examples described later, and other printing methods such as gravure printing, offset printing, ink jet, dispenser, and dipping can also be applied. Therefore, the conductive adhesive composition according to the present disclosure may be used as long as it can be applied onto a substrate by a printer or a dispenser.

The conductive adhesive composition according to the present disclosure can be widely used for forming high-definition electrodes, wiring, etc., bonding electronic parts, and the like. Specifically, for example, collector electrodes of solar cells; internal or external electrodes of chip-type electronic components; RFID (Radio Frequency IDentification), electromagnetic wave shielding, vibrator adhesion, membrane switches, touch panels, electroluminescence, etc. It can be suitably used for applications such as electrodes, wiring, or adhesion of parts used for.

Typical applications of the conductive adhesive composition according to the present disclosure include, for example, the field of solar cells. Specifically, the conductive adhesive composition according to the present disclosure can be suitably used for adhesion of solar cell modules, for example.

As shown in FIG. 1B, a typical solar cell module 30 has a structure (string system) in which a plurality of solar cells 31 are connected by a ribbon-shaped wiring member called an interconnector 32 . In recent years, as shown in FIG. 1A, a plurality of solar cells 21 are partially arranged so that the lower surface of the long side of an arbitrary solar cell 21 overlaps the upper surface of the long side of another solar cell 21. A so-called single-module type solar cell module 20 has also been proposed, in which the solar cell modules 20 are stacked one on top of the other and arranged obliquely.

In such a single module type solar cell module 20 , a conductive adhesive is used instead of the interconnector 32 for connecting the solar cells 21 . In this case, the solar cells 21 are adherends, and a conductive adhesive is applied between the lower surface of the long side of one solar cell 21 and the upper surface of the long side of the other solar cell 21 and cured. As a result, a cured product of the conductive adhesive, that is, a cured adhesive layer 22 is formed between the solar cells 21 . The cured adhesive layer 22 adheres the solar cells 21 to each other in an electrically connectable state. It should be noted that the conductive adhesive can also be used when adhering the solar cell module 30 to the solar cell 31 of the interconnector 32 .

Here, since both the conventional type (string type) solar cell module 30 and the single module type solar cell module 20 are installed outdoors, the daily temperature difference (temperature difference) between the high temperature during the day and the low temperature during the night is not sufficient. exposed. If such a heat cycle occurs due to repetition of high and low temperatures, the cured adhesive layer 22, which is a cured product of the conductive adhesive, may be affected by thermal change.

On the other hand, the conductive adhesive composition according to the present disclosure contains (A) a conductive powder and a curable component, and when the total mass is 100% by mass, the content of the curable component is 10% by mass or more, and the curable components include at least (B) a radically polymerizable silicone monomer that is curable component 1, and (C) curable component 2 that is cured within the range of 100° C. to 200° C. In this configuration, an addition-curing reactive silicone resin is used.

According to this configuration, both good conductivity and good adhesive strength can be achieved by using two types of curable components, namely, a radically polymerizable silicone monomer and an addition-curable reactive silicone resin. Therefore, in either the solar cell module 30 shown in FIG. 1A or the solar cell module 20 shown in FIG. Good adhesion between adherends (solar cell 21 in solar cell module 30, solar cell 31 and interconnector 32 in solar cell module 30) while ensuring good electrical connectivity between adherends becomes possible.

Moreover, by using these two types of silicone compounds together as curable components, it is possible to shorten the curing time for both 150° C. curing and 200° C. curing. Therefore, it is possible to achieve not only better adhesion but also more efficient curing. As a result, it becomes possible to make the production of the solar cell module (or the electronic component described above) more efficient.

Further, the conductive adhesive composition according to the present disclosure contains (D) spacer particles in addition to (A) the conductive powder and the two curable components. The (D) spacer particles are at least one of glass particles, ceramic particles, or silicone particles (typically silicone particles), and when the total volume of the curable components is 100% by volume, the content The amount is in the range of 0.1-10.0% by volume. As a result, it is possible not only to ensure a good thickness in the cured adhesive layer after curing, but also to effectively suppress the possibility that the cured adhesive layer 22 spreads out from the adhesive region.

If the thickness of the cured adhesive layer 22 cannot be maintained and spreads significantly, the cured adhesive layer 22 protrudes from the adherend, resulting in poor appearance. Furthermore, if the amount of the conductive adhesive is reduced to prevent the cured adhesive layer 22 from protruding, the cured adhesive layer 22 may not have sufficient properties (adhesive strength, conductivity, reliability, etc.). According to the present disclosure, the (D) spacer particles are blended in an appropriate amount, so that the cured adhesive layer 22 can not only achieve a good thickness, but also can suppress protrusion, thereby achieving good shape retention. be able to. As a result, appearance defects can be suppressed and the cured adhesive layer can achieve good properties.

Moreover, if (D) the spacer particles are silicone particles that are of the same material as the silicone-based curable component, the cured adhesive layer 22 can achieve good adhesion strength while ensuring good electrical conductivity. can. In addition, (D) the effect of stress relaxation by the spacer particles can also be expected, so that the adhesive strength of the cured adhesive layer 22 can be further improved. Therefore, the conductive adhesive composition according to the present disclosure is particularly useful for manufacturing the solar cell module 20 as shown in FIG. 1(A), the solar cell module 30 as shown in FIG. It can be applied well to the production of parts.

The present invention will be described in more detail based on Reference Examples, Examples and Comparative Examples, but the present invention is not limited thereto. Various changes, modifications and alterations can be made by those skilled in the art without departing from the scope of the invention. The physical properties and the like in the following reference examples, examples and comparative examples were measured and evaluated as follows.

[Method for evaluating conductive powder and spacer particles]
(1) Median Size The median size of (A) the conductive powder or (D) the spacer particles was evaluated by a laser diffraction method. A 0.3 g sample of (A) conductive powder or (D) spacer particles is weighed into a 50 ml beaker, 30 ml of isopropyl alcohol is added, and then treated for 5 minutes with an ultrasonic cleaner (USM-1 manufactured by AS ONE Corporation). Then, the median diameter was measured and evaluated using a particle size distribution analyzer (Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd.).

(2) CV value Using the median diameter of the (D) spacer particles obtained by the above method, the standard deviation of the particle diameter of the (D) spacer particles is divided by the median diameter to obtain a CV value (Coefficient of Variation) was calculated.

[Evaluation of shape after application of conductive adhesive composition]
The conductive adhesive composition of Example or Comparative Example was applied to an alumina substrate using a dispenser so as to have a diameter of 60 μm and a height of 200 μm, and a glass substrate weighing 5 g was laminated thereon. This substrate laminate was heated at 150° C. for 30 seconds using a hot plate to cure the conductive adhesive composition (formation of cured adhesive layer). Thus, an evaluation sample for shape evaluation after attachment was obtained.

The spread of the cured adhesive layer from the surface of the evaluation sample on the glass substrate side was measured with an optical measuring microscope. When the diameter of the cured adhesive layer was less than 900 μm, it was evaluated as “◯”, and when it was 900 μm or more, it was evaluated as “x”. Also, the thickness of the cured adhesive layer was measured with an optical measuring microscope. When the thickness of the cured adhesive layer was 30 μm or more, it was evaluated as “◯”, and when it was less than 30 μm, it was evaluated as “×”.

[Evaluation of Adhesive Strength of Conductive Adhesive Composition]
The conductive adhesive composition of Examples or Comparative Examples was printed on an alumina substrate using a printing machine so as to form a square pad pattern of 2 mm×2 mm. An aluminum rivet having a circular fixing surface with a diameter of 4 mm was placed on a pad pattern (2 mm×2 mm) on an alumina substrate.

The alumina substrate on which the rivets are mounted is placed in a box furnace and heated at 150° C. for 10 minutes or 200° C. for 10 minutes in an air atmosphere to cure the conductive adhesive composition (pad pattern). Formation of Adhesive Layer), and evaluation samples for adhesive strength were obtained.

For each evaluation sample cured at 150° C. or 200° C., a horizontal shearing force was applied to the rivet mounted on the pad pattern, and the strength when the rivet separated from the pad pattern was measured. If the strength is 15 N / 2 mm square or more, "O", if it is 10 N / 2 mm square or more and less than 15 N / 2 mm square, "△", if it is less than 10 N / 2 mm square, "X". Conductive adhesive composition The adhesive strength of (cured adhesive layer) was evaluated.

[Evaluation of conductivity of conductive adhesive composition]
The conductive adhesive compositions of Examples or Comparative Examples were printed in a linear pattern on an alumina substrate using a printer. The linear pattern had a width of 500 μm, a length of 37.5 mm, and a thickness of about 15 μm.

The printed alumina substrate is placed in a box furnace and heated at 150° C. for 10 minutes or 200° C. for 10 minutes in an air atmosphere to cure the conductive adhesive composition (linear pattern) (curing adhesion layer formation), and a conductive evaluation sample was obtained.

For each evaluation sample cured at 150° C. or 200° C., the electrical resistance of the linear pattern was measured with a digital multimeter (R6551 manufactured by Advantest Co., Ltd.). The electrical conductivity of the conductive adhesive composition (cured adhesive layer) was evaluated by assigning "○" when the resistance value was 100Ω or less, "Δ" when it was 1000Ω or less, and "X" when it exceeded 1000Ω.

[(A) conductive powder, (B) curable component 1 and (C) curable component 2]
In the following reference examples, examples, and comparative examples, two types of powder shown in Table 1 below were used as (A) conductive powder.

Further, in the following reference examples, examples, and comparative examples, of the two types of curable components, (B) curable component 1: radically polymerizable silicone monomer, methacrylic group or acrylic group-containing polydimethyl shown in Table 1 below Siloxane was used, and a silicone resin shown in Table 1 below was used as (C) curable component 2: addition curing reactive silicone resin. The abbreviations in Table 1 below are used to indicate the components of Reference Examples, Examples and Comparative Examples in Tables 4 to 8.

［その他の成分］
以下の参考例、実施例または比較例では、その他の成分として、下記表２に示す各種の成分を用いた。

[Other ingredients]
In the following reference examples, examples and comparative examples, various components shown in Table 2 below were used as other components.

［（Ｄ）スペーサー粒子］
以下の実施例または比較例では、（Ｄ）スペーサー粒子として、下記表３に示す８種類の粒子を用いた。なお、表３にも付記しているが、Ｄ４およびＤ６の複合シリコーン球状粒子とは、ゴム状シリコーン球状粒子の表面にシリコーン樹脂が被覆された構成の球状粒子である。また、Ｄ５のゴム状シリコーン球状粒子は凝集粒子を含むため、そのＣＶ値は、粒度分布チャートに基づいて一次粒子のみとしたときの算出値とした。

[(D) spacer particles]
In the following examples and comparative examples, eight types of particles shown in Table 3 below were used as (D) spacer particles. As shown in Table 3, the composite silicone spherical particles D4 and D6 are spherical particles in which the surfaces of rubber-like silicone spherical particles are coated with a silicone resin. In addition, since the rubber-like silicone spherical particles of D5 contain agglomerated particles, the CV value was calculated based on the particle size distribution chart for primary particles only.

（参考例１）
表４に示すように、（Ａ）導電性粉末として、表１に示す球状の銀粉１（略号Ａ１）およびフレーク状の銀粉２（略号Ａ２）を用い、（Ｂ）硬化性成分１として、表１に示す、２種類のメタクリル基含有単官能ポリジメチルシロキサン（略号Ｂ１および略号Ｂ１１）を用い、その他の成分として、表１に示すカップリング剤、重合開始剤、付加硬化反応触媒、および増量剤を用い、これらを表４に示す配合量（質量部）となるよう配合し、これら各成分を３本ロールミルで混練した。これにより、（Ｄ）スペーサー粒子を含有しない参考例１の導電性接着剤組成物を調製（製造）した。

(Reference example 1)
As shown in Table 4, as (A) conductive powder, spherical silver powder 1 (abbreviation A1) and flaky silver powder 2 (abbreviation A2) shown in Table 1 are used, and (B) as curable component 1, 1, using two types of methacrylic group-containing monofunctional polydimethylsiloxane (abbreviation B1 and abbreviation B11), and as other components, a coupling agent, a polymerization initiator, an addition curing reaction catalyst, and an extender shown in Table 1 were blended so as to have the blending amounts (parts by mass) shown in Table 4, and these respective components were kneaded in a three-roll mill. Thus, (D) a conductive adhesive composition of Reference Example 1 containing no spacer particles was prepared (manufactured).

In addition, in the conductive adhesive composition of Reference Example 1, of the two curable components, (C) curable component 2 is not used, so (B) curable component 1 and (C) curable component in Table 4 The compounding ratio (mass ratio, abbreviated as (B)/(C) in Table 4) with the organic component 2 was 100/0.

For the obtained conductive adhesive composition, as described above, an adhesive strength evaluation sample and a conductive evaluation sample were prepared, and these evaluation samples were used to form the cured adhesive layer (conductive adhesive composition) of Reference Example 1. The adhesive strength after curing at 150°C or 200°C and the conductivity (resistance value) after curing at 150°C or 200°C were evaluated. Table 4 shows the results. In addition, in Table 4 (and Table 6), the adhesive strength is simply described as "strength", and the evaluation of conductivity is described as "resistance value".

(Reference examples 2 to 4)
(C) Addition-curable silicone resin shown in Table 1 as curable component 2 (a silicone resin in which a silicone polymer having a vinyl group and an H group is cured by a hydrosilylation reaction in the presence of a catalyst, a curing temperature of 100 to 200° C., abbreviation C1 ), and as shown in Table 4, the compounding ratio of (B) curable component 1 and (C) curable component 2 is (B) / (C) = 75/25, 50/50, 25/75 Conductive adhesive compositions of Reference Examples 2 to 4 were prepared (manufactured) in the same manner as in Reference Example 1, except that the

For the obtained conductive adhesive composition, an evaluation sample was prepared in the same manner as in Reference Example 1, and the cured adhesive layer (conductive adhesive composition) of Reference Examples 2 to 4 was cured at 150 ° C. or cured at 200 ° C. Strength and conductivity (resistance value) after curing at 150° C. or 200° C. were evaluated. Table 4 shows the results.

(Reference example 5)
As shown in Table 4, the conductive adhesion of Reference Example 5 was performed in the same manner as in Reference Example 1, except that (B) curable component 1 was not used as the curable component and (C) only curable component 2 was used. A composition was prepared (manufactured). The compounding ratio of (B) curable component 1 and (C) curable component 2 in Table 4 is (B)/(C)=0/100.

For the obtained conductive adhesive composition, an evaluation sample was prepared in the same manner as in Reference Example 1, and the adhesive strength of the cured adhesive layer (conductive adhesive composition) of Reference Example 5 after curing at 150 ° C. or 200 ° C. In addition, the conductivity (resistance value) after curing at 150° C. or 200° C. was evaluated. Table 4 shows the results.

(Reference example 6)
As shown in Table 4, the same procedure as in Reference Example 3 (that is, (B )/(C)=50/50), a conductive adhesive composition of Reference Example 6 was prepared (manufactured) in the same manner as in Reference Example 1.

For the obtained conductive adhesive composition, an evaluation sample was prepared in the same manner as in Reference Example 1, and the adhesive strength of the cured adhesive layer (conductive adhesive composition) of Reference Example 6 after curing at 150 ° C. or 200 ° C. In addition, the conductivity (resistance value) after curing at 150° C. or 200° C. was evaluated. Table 4 shows the results.

（参考例１～６の対比）
表４に示すように、硬化性成分として（Ｂ）硬化性成分１：ラジカル重合性シリコーンモノマーおよび（Ｃ）硬化性成分２：付加硬化反応性シリコーン樹脂を併用した参考例２～４では、硬化接着層（導電性接着剤組成物）の接着強度（表中「強度」）も導電性（表中「抵抗値」）も１５０℃硬化および２００℃硬化のいずれも良好な結果を示すことがわかる。

(Comparison with Reference Examples 1 to 6)
As shown in Table 4, in Reference Examples 2 to 4 in which (B) curable component 1: radically polymerizable silicone monomer and (C) curable component 2: addition-curable reactive silicone resin were used together as curable components, curing It can be seen that both the adhesive strength (“strength” in the table) and conductivity (“resistance value” in the table) of the adhesive layer (conductive adhesive composition) show good results at both 150° C. curing and 200° C. curing. .

On the other hand, in Reference Example 1, in which only the (B) curable component 1 was used as the curable component, good results were obtained in terms of conductivity, but sufficient results were not obtained in terms of adhesive strength. In addition, in Reference Example 5 using only (C) curable component 2 as a curable component, good adhesive strength is obtained only in the case of curing at 200 ° C., but sufficient adhesive strength is not obtained in curing at 150 ° C., It can be seen that both 150° C. curing and 200° C. curing do not provide satisfactory results in terms of conductivity.

Furthermore, in Reference Example 6 using an addition-curable reactive silicone resin (addition-curable silicone rubber) that cures at 60° C. instead of the 150-200° C.-curable type (addition-curable silicone rubber) as (C) curable component 2, adhesive strength and conductivity In either case, it can be seen that sufficient results cannot be obtained regardless of whether the curing is performed at 150°C or 200°C.

(Comparative example 1)
As shown in Table 5, as (B) curable component 1, a conductive adhesive composition was prepared (manufactured) so as to have the composition shown in Table 1 (the total composition being 100% by mass). This conductive adhesive composition corresponds to the conductive adhesive composition of Reference Example 3. Note that this Comparative Example 1 does not contain (D) spacer particles. For the obtained conductive adhesive composition, an adhesive strength evaluation sample and a conductive evaluation sample were prepared in the same manner as in Reference Example 1, and the cured adhesive layer (conductive adhesive composition) of Comparative Example 1 C. or 200.degree. C. curing adhesive strength, and 150.degree. C. or 200.degree. C. curing conductivity (resistance value) were evaluated. Table 5 shows the results.

Further, for the obtained conductive adhesive composition, as described above, an evaluation sample for evaluating the shape after attachment was prepared, and the cured adhesive layer (conductive adhesive composition) of Comparative Example 1 was prepared using this evaluation sample. The thickness and spreading (bleeding) were evaluated. Table 5 shows the results. In Table 5 (and Tables 5 to 8), the thickness of the cured adhesive layer is described as "adhesive layer thickness", and the spread (bleeding) of the cured adhesive layer is described as "adhesive layer spread".

(Example 1)
As shown in Table 5, the same as Comparative Example 1 except that 0.5% by volume of the silver-coated glass particles shown in Table 3 (silver coating amount: 12% by mass, abbreviation D1) was added as spacer particles (D). Then, the conductive adhesive composition of Example 1 was prepared (manufactured). In addition, the content of (D) spacer particles is obtained by calculating the volume of the entire curable component from the densities of (B) curable component 1 and (C) curable component 2 shown in Table 5 as described above. It is defined as a volume fraction based on

For the obtained conductive adhesive composition, in the same manner as in Comparative Example 1, an adhesive strength evaluation sample, a conductivity evaluation sample, and an evaluation sample for shape evaluation after application were prepared. For the cured adhesive layer (conductive adhesive composition), the adhesive strength after curing at 150 ° C. or 200 ° C., the conductivity (resistance value) after curing at 150 ° C. or 200 ° C., and its thickness and spreading (bleeding) were evaluated. did. Table 5 shows the results.

As described above, the amount of the spacer particles (D) added is the volume ratio (% by volume) of the spacer particles (D) added to the total amount of the curable component when the total amount is 100% by mass. In Example 1 and Examples 2 to 10 or Comparative Examples 2 to 7 described later, the curable components were (B) curable component 1: radically polymerizable silicone monomer and (C) curable component 2: addition curing reaction. Since two kinds of silicone resins are used, the total amount of these is the standard for the amount of spacer particles (D) added.

(Examples 2 to 5, Comparative Example 2)
As shown in Table 5 or Table 6, (D) spacer particles include glass particles (abbreviation D2), acrylic particles (abbreviation D3), composite silicone spherical particles 1 (abbreviation D4), and rubber-like silicone spherical particles shown in Table 3. (abbreviation D5) or the conductive adhesive composition of Examples 2 to 5 or Comparative Example 2 was prepared in the same manner as in Example 1 except that 0.5% by volume of Composite Silicone Spherical Particles 2 (abbreviation D6) was added. Prepared (manufactured).

For each of the obtained conductive adhesive compositions, in the same manner as in Comparative Example 1, an adhesive strength evaluation sample, a conductivity evaluation sample, and an evaluation sample for shape evaluation after application were prepared. For each of the cured adhesive layer (conductive adhesive composition) of ~ 5 or Comparative Example 2, the adhesive strength at 150 ° C. or 200 ° C. curing, the conductivity (resistance value) at 150 ° C. or 200 ° C. curing, and its Thickness and spreading (bleeding) were evaluated. The results are shown in Table 5 or 6 (however, resistance values for curing at 200° C. are only for Examples 3 to 5, 6 and 7).

（比較例３、実施例６、実施例７）
表６に示すように、（Ｄ）スペーサー粒子として、表３に示すアクリル粒子（略号Ｄ３）、または複合シリコーン球状粒子２（略号Ｄ６）を１．０体積％添加するか（比較例３または実施例６）、複合シリコーン球状粒子２（略号Ｄ６）を３．０体積％添加した（実施例７）以外は実施例１と同様にして、比較例３、実施例６または実施例７の導電性接着剤組成物を調製（製造）した。

(Comparative Example 3, Example 6, Example 7)
As shown in Table 6, 1.0% by volume of acrylic particles (abbreviation D3) or composite silicone spherical particles 2 (abbreviation D6) shown in Table 3 are added as (D) spacer particles (Comparative Example 3 or Experimental Example 6), in the same manner as in Example 1 except that 3.0% by volume of composite silicone spherical particles 2 (abbreviation D6) was added (Example 7), Comparative Example 3, Example 6, or the conductivity of Example 7 An adhesive composition was prepared (manufactured).

For each of the obtained conductive adhesive compositions, in the same manner as in Comparative Example 1, an adhesive strength evaluation sample, a conductive evaluation sample, and an evaluation sample for shape evaluation after application were prepared. , for each cured adhesive layer (conductive adhesive composition) of Example 6 or Example 7, adhesive strength at 150 ° C. or 200 ° C. curing, conductivity (resistance) at 150 ° C. or 200 ° C. curing, and , its thickness and spreading (bleeding) were evaluated. Table 6 shows the results.

（比較例４）
全質量中の（Ａ）導電性粉末の成分比を、比較例１の６０質量％から６９質量％となるように各成分を調整するとともに、表７に示すように、（Ｂ）硬化性成分１：ラジカル重合性シリコーンモノマーとして、表１に示す２種類のメタクリル基含有単官能ポリジメチルシロキサン（略号Ｂ２および略号Ｂ１２）を用いた以外は、比較例１と同様にして、比較例４の導電性接着剤組成物を調製（製造）した。なお、この比較例４には、比較例１または参考例３等と同様に（Ｄ）スペーサー粒子は含有していない。

(Comparative Example 4)
Each component was adjusted so that the component ratio of (A) conductive powder in the total mass was 60% by mass to 69% by mass in Comparative Example 1, and as shown in Table 7, (B) curable component 1: Conductivity of Comparative Example 4 was obtained in the same manner as in Comparative Example 1 except that two types of methacrylic group-containing monofunctional polydimethylsiloxanes (abbreviations B2 and B12) shown in Table 1 were used as radically polymerizable silicone monomers. A flexible adhesive composition was prepared (manufactured). Incidentally, in Comparative Example 4, like Comparative Example 1 or Reference Example 3, (D) spacer particles were not contained.

For the obtained conductive adhesive composition, in the same manner as in Comparative Example 1, an adhesive strength evaluation sample, a conductive evaluation sample, and an evaluation sample for shape evaluation after application were prepared. The cured adhesive layer (conductive adhesive composition) was evaluated for adhesive strength after curing at 150° C. or 200° C., conductivity (resistance value) after curing at 150° C., and thickness and spreading (bleeding). Table 7 shows the results.

(Comparative Examples 5-7)
As shown in Table 7, (B) curable component 1: As a radically polymerizable silicone monomer, two types of methacrylic group-containing monofunctional polydimethylsiloxanes shown in Table 1 (abbreviations B1 and B11, Reference Examples 1 to 6, Comparative Examples 1 to 3, same as Examples 1 to 7), acrylic particles (abbreviation D3) shown in Table 3 are used as (D) spacer particles, and the amount of the (D) spacer particles added is 0.5. In the same manner as in Comparative Example 4 except that it was changed to vol% (Comparative Example 5), 1.0 vol% (Comparative Example 6), and 3.0 vol% (Comparative Example 7) (that is, (A) conductive powder content of 69% by mass), conductive adhesive compositions of Comparative Examples 5 to 7 were prepared (manufactured).

For each of the obtained conductive adhesive compositions, in the same manner as in Comparative Example 1, an adhesive strength evaluation sample, a conductive evaluation sample, and an evaluation sample for shape evaluation after application were prepared. For each cured adhesive layer (conductive adhesive composition) of ~ 7, the adhesive strength after curing at 150 ° C. or 200 ° C., the conductivity (resistance value) after curing at 150 ° C., and its thickness and spreading (bleeding) were evaluated. did. Table 7 shows the results.

（実施例８～１０）
表８に示すように、（Ｄ）スペーサー粒子として、表３に示す複合シリコーン球状粒子２（略号Ｄ６）を用い、当該（Ｄ）スペーサー粒子の添加量を０．５体積％（実施例８）、１．０体積％（実施例９）、３．０体積％（実施例１０）に変化させた以外は比較例５～７と同様にして（すなわち（Ａ）導電性粉末の含有量を６９質量％として）、実施例８～１０の導電性接着剤組成物を調製（製造）した。

(Examples 8-10)
As shown in Table 8, composite silicone spherical particles 2 (abbreviation D6) shown in Table 3 were used as (D) spacer particles, and the amount of the (D) spacer particles added was 0.5% by volume (Example 8). , 1.0% by volume (Example 9) and 3.0% by volume (Example 10) in the same manner as in Comparative Examples 5 to 7 (that is, the content of (A) the conductive powder was changed to 69 % by weight), the conductive adhesive compositions of Examples 8-10 were prepared (manufactured).

For each of the obtained conductive adhesive compositions, in the same manner as in Comparative Example 1, an adhesive strength evaluation sample, a conductivity evaluation sample, and an evaluation sample for shape evaluation after application were prepared. For each of ~10 cured adhesive layers (conductive adhesive composition), adhesive strength at 150°C curing or 200°C curing, conductivity (resistance value) at 150°C curing or 200°C curing, and its thickness and spread ( bleeding) was evaluated. Table 8 shows the results.

(Examples 11-13)
As shown in Table 8, composite silicone spherical particles 2 (abbreviation D6) shown in Table 3 were used as (D) spacer particles, and the amount of the (D) spacer particles added was 0.1% by volume (Example 11). , 5.0% by volume (Example 12) and 10.0% by volume (Example 13) in the same manner as in Example 5 (that is, the content of (A) the conductive powder was changed to 60% by mass as), the conductive adhesive compositions of Examples 11-13 were prepared (manufactured).

For each of the obtained conductive adhesive compositions, in the same manner as in Comparative Example 1, an adhesive strength evaluation sample, a conductivity evaluation sample, and an evaluation sample for shape evaluation after application were prepared. For each of ~13 cured adhesive layers (conductive adhesive compositions), the adhesive strength at 150 ° C curing or 200 ° C curing, the conductivity (resistance value) at 150 ° C curing or 200 ° C curing, and its thickness and spread ( bleeding) was evaluated. Table 8 shows the results.

（実施例１４）
参考例１と同じ組成であって、（Ｄ）スペーサー粒子としての複合シリコーン球状粒子２（略号Ｄ６）の含有量を０体積％、１体積％、２体積％、および３体積％に変化させた４種類の導電性接着剤組成物を調製（製造）し、これらを用いて前述した接着強度の評価サンプルを４種類作製し、それぞれの評価サンプルについてヒートサイクル試験（温度サイクル（ＴＣ：Thermal Cycle）試験）を実施した。

(Example 14)
The composition was the same as in Reference Example 1, but the content of (D) composite silicone spherical particles 2 (abbreviation D6) as spacer particles was changed to 0% by volume, 1% by volume, 2% by volume, and 3% by volume. Four types of conductive adhesive compositions were prepared (manufactured), four types of adhesive strength evaluation samples were prepared using these, and each evaluation sample was subjected to a heat cycle test (temperature cycle (TC) test) was performed.

Note that (D) the composition with a spacer particle content of 0% by volume corresponds to Comparative Example 1 (Reference Example 1), (D) the composition with a spacer particle content of 1% by volume corresponds to Example 6, ( D) The composition with a spacer particle content of 3% by volume corresponds to Example 7.

In addition, as a heat cycle test device, a small thermal shock device model TSE-11-A manufactured by Espec Co., Ltd. was used. Set the change speed within 1 minute, set the conditions such that one cycle is from high temperature (90 ° C.) to low temperature (-40 ° C.) to high temperature (90 ° C.) again, and set the initial adhesive strength to 100 ( Reference), the decrease in the adhesive strength of the evaluation sample after repeating the heat cycle multiple times was evaluated as a relative value (%). The results are shown in FIG.

(Comparison of Reference Example, Example and Comparative Example)
From the comparison of Reference Examples 1 to 6 and Comparative Examples 1 and 4, (D) the conductive adhesive composition having a composition not containing spacer particles contained (B) curable component 1 as a curable component: It can be seen that both good electrical conductivity and good adhesion can be achieved by using two kinds of radically polymerizable silicone monomer and (C) curable component 2: addition-curable reactive silicone resin.

Further, from a comparison between Comparative Example 1 and Examples 1 to 5, the inclusion of (D) spacer particles enables the thickness of the adhesive layer to be maintained well in the conductive adhesive composition, and the spread of the adhesive layer ( Bleeding) can be satisfactorily avoided.

However, from a comparison between Examples 1 to 5 and Comparative Example 2, it can be seen that when acrylic particles (abbreviation D3) are used as (D) spacer particles, good adhesive strength cannot be obtained. A similar result can also be seen from the comparison of Comparative Example 3 and Example 6 in which the content of (D) spacer particles was increased. In other words, when the (D) spacer particles are made of an acrylic material, even if the content of the (D) spacer particles is increased, the adhesive strength is not improved.

On the other hand, when composite silicone spherical particles 2 (abbreviation D6) were used as (D) spacer particles, the content of (D) spacer particles was increased, as is clear from the results of Examples 5 to 7. It can be seen that good adhesive strength can be achieved in some cases, and good results can be obtained in other evaluations (resistance value, adhesive layer thickness, adhesive layer spread).

Furthermore, the content of (A) the conductive powder was increased from Examples 1 to 7 and Comparative Examples 2 and 3 ((A) The content of the conductive powder was increased from 60% by mass to 69% by mass ) Also in Comparative Examples 4 to 7, when the (D) spacer particles are acrylic particles (abbreviation D3), good adhesive strength cannot be obtained even if the content is increased or decreased, especially in Comparative Examples 4 and 5 to 7 suggests that the inclusion of D3:acrylic particles as (D) spacer particles may result in a decrease in adhesive strength.

On the other hand, in Examples 8 to 10 in which (A) the content of the conductive powder was increased, (D) composite silicone spherical particles 2 (abbreviation D6) were used as the spacer particles. Similar to 5 to 7, good adhesive strength can be achieved when the content of (D) spacer particles is increased, and good results are obtained in other evaluations (resistance value, adhesive layer thickness, adhesive layer spread). It is understood that

Similarly, (A) the content of the conductive powder is not increased from that of Example 5 (that is, (A) the content of the conductive powder is 60% by mass, and (D) the spacer particles are composite silicone spherical particles 2 (abbreviation D6)) In Examples 11 to 13 as well, when the content of (D) spacer particles is increased, good adhesive strength can be achieved, and other evaluations (resistance value, adhesive layer thickness, adhesive layer spread) good results can be obtained.

In particular, in Example 11, the content of (D) the spacer particles was reduced to 0.1% by volume, but good results were obtained in all of the adhesive strength, resistance value, adhesive layer thickness, and adhesive layer spread. have been obtained. In Example 12, the content of the (D) spacer particles was increased to 5.0% by volume, and good results were obtained in all of the adhesive strength, resistance value, adhesive layer thickness, and adhesive layer spread. have been obtained.

Furthermore, in Example 13, the content of the (D) spacer particles was increased to 10.0% by volume. It can be seen that this is feasible and good results can be obtained for other evaluations (resistance value, adhesive layer thickness, adhesive layer spread). Also, based on the results of Examples 8 to 13, if the content of (D) spacer particles is 0.1% by mass or exceeds 10.0% by mass, it is possible that good results cannot be obtained. I know there is a gender.

Also, as is clear from FIG. 2, that is, the results of Example 14, (D) compared to a conductive adhesive composition containing no spacer particles (0% by volume, solid line with triangle symbols in FIG. 2), ( D) Even when the spacer particle content is 1% by volume (circular symbol dotted line in FIG. 2), the adhesive strength retention rate is sufficiently high, and the content is 2% by volume (square symbol dashed line in FIG. 2) or 3 volumes % (broken line with rhombic symbols in FIG. 2), the adhesive strength retention increases.

Also, when the number of heat cycles reaches 200, the adhesive strength decreases to the same extent as when the content of (D) spacer particles is 1% by volume or 2% by volume, but the content is 3%. In the case of vol%, it can be seen that the adhesive strength equivalent to 100 heat cycles can be achieved at a content of 2 vol%. In other words, the increase in the amount of the (D) spacer particles tends to improve the durability against heat cycles, so the (D) spacer particles exhibit stress relaxation effects in the conductive adhesive composition (cured adhesive layer). It is possible that

It should be noted that the present invention is not limited to the description of the above embodiments, and various modifications are possible within the scope of the claims, and different embodiments and multiple modifications are disclosed respectively. Embodiments obtained by appropriately combining the above technical means are also included in the technical scope of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be widely and suitably used in the field of conductively bonding adherends in the field of electrical equipment or electronic equipment. Typically, it can be particularly preferably used in the field of manufacturing solar cell modules.

20: Solar cell module 21: Solar cell 22: Cured adhesive layer 30: Solar cell module 31: Solar cell 32: Interconnector

Claims (7)

(A) contains a curable component that is a conductive powder and a silicone compound, and the content of the curable component is 10% by mass or more when the total mass is 100% by mass;
As the curable component, at least
(B) a radically polymerizable silicone monomer as curable component 1, and
(C) an addition-curable reactive silicone resin that cures within the range of 100° C. to 200° C. is used as curable component 2,
Furthermore, (D) spacer particles having a larger average particle diameter (median diameter) than the (A) conductive powder,
The (D) spacer particles are at least one of glass particles, ceramic particles, organic resin particles other than acrylic particles, or silicone particles,
When the total volume of the curable components is 100% by volume, the content of the (D) spacer particles is 0.1% by volume or more and 10.0% by volume or less,
A conductive adhesive composition. (D) the spacer particles are silicone particles,
The conductive adhesive composition according to claim 1. A monofunctional monomer and a bifunctional monomer are used in combination as the (B) curable component 1, which is a radically polymerizable silicone monomer.
The conductive adhesive composition according to claim 1 or 2. The average particle diameter (median diameter) of the (D) spacer particles is in the range of 10 to 60 μm, and the CV value (Coefficient of Variation) of the (D) spacer particles is 30% or less. ,
A conductive adhesive composition according to any one of claims 1 to 3. The (A) conductive powder is a metal powder composed of at least one metal selected from the group of Ag, Cu, Ni, Al, and Pd,
An alloy powder containing one or more metals selected from the above group, or
A coated powder having a surface coated with one or more metals selected from the above group,
A conductive adhesive composition according to any one of claims 1 to 4. It is used by applying it on a substrate with a printer or dispenser,
A conductive adhesive composition according to any one of claims 1 to 5. Characterized by being used for bonding solar cells constituting a solar cell module,
The conductive adhesive composition according to claim 6.

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