JP6656509B1 - Method for producing conductive filler, conductive addition-curable silicone composition, and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a conductive filler which does not impair storage stability and thermal stability of a cured product even when compounded with a curable silicone composition, storage stability before curing and thermal stability of a cured product. Provided are an excellent conductive curable silicone composition and a highly reliable semiconductor device. SOLUTION: A method for producing a conductive filler, which comprises subjecting conductive particles having a surface coated with a fatty acid to a surface treatment with an organoalkoxysilane containing an epoxy group, and further treating with organosilazane, and the addition of the conductive filler. A conductive addition reaction-curable silicone composition comprising a reaction-curable silicone composition, and a semiconductor device in which a semiconductor element is covered with a cured product of the conductive addition-curable silicone composition. [Selection diagram] Fig. 1

Description

The present invention relates to a method for producing a conductive filler, a conductive addition-curable silicone composition, and a semiconductor device.
Specifically, a method for producing a conductive filler, in which a conductive particle whose surface is coated with a fatty acid is surface-treated with an epoxy group-containing organoalkoxysilane, and further treated with an organosilazane, contains the conductive filler thus produced. The present invention relates to a conductive addition reaction-curable silicone composition and a semiconductor device in which a semiconductor element is covered with a cured product of the conductive addition reaction-curable silicone elastomer composition.

Liquid silicone elastomer compositions containing thermally conductive and conductive fillers such as inorganic and metallic materials with thermal conductivity and conductivity are used as adhesives, potting agents, and protective coatings for electrical and electronic components. Have been. Liquid silicone composition of addition reaction curing type comprising liquid organopolysiloxane having a silicon-bonded alkenyl group, liquid organopolysiloxane having a silicon-bonded hydrogen atom, an addition reaction catalyst, and a heat conductive and conductive filler as essential components. Are disclosed in, for example, JP-A-2-97559 and JP-A-2-41362. Such a liquid silicone elastomer composition cures into a low-stress elastomer having excellent heat resistance, heat conductivity, and conductivity, and is used as an adhesive, potting agent, and protective coating agent for electric and electronic parts. It is used as an adhesive between a semiconductor element and a heat sink. The metallic particulate filler such as silver is excellent not only in heat conductivity but also in conductivity.

Such a heat conductive, conductive silicone elastomer composition is a heat conductive, conductive addition reaction curable organopolysiloxane composition containing a large amount of silver particles in order to further enhance the heat conductivity and conductivity. It has been proposed (JP-A-2-238054). The cured product of this composition has excellent thermal conductivity and conductivity, but commercially available silver particles have an organic substance such as a fatty acid remaining as a dispersant (coating agent) for preventing aggregation during production, The surface has been treated or coated with the organic substance. When such silver particles are added to a silicone elastomer composition, the thermal conductivity and conductivity of the cured product are improved, but the thermal stability is significantly reduced, and the reliability of a semiconductor device using the same is significantly reduced. There is a problem of lowering.

Therefore, for the purpose of improving the thermal stability of the cured product, a silver particle whose surface is treated or coated with an organic substance such as a fatty acid is further treated or coated with an epoxy group-containing compound and a curing agent for an epoxy resin. Functional fillers have been proposed (JP-A-2004-83905). However, the present inventors have noticed that the liquid or paste conductive silicone elastomer composition containing this conductive filler has a problem that storage stability (pot life) is extremely low.

JP-A-2-97559 JP-A-2-41362 JP-A-2-238054 JP 2004-83905 A

The present inventors have conducted intensive studies on the above problems, and as a result, the conductive particles whose surfaces are coated with a fatty acid have been surface-treated with an epoxy group-containing organoalkoxysilane, and the conductive particles further treated with an organosilazane. Then, they found that there was no such problem, and reached the present invention.

An object of the present invention is to provide a liquid or paste-form addition-reaction-curable silicone composition that has a small increase in viscosity during storage and excellent storage stability, and has a high heat stability of a cured product of the composition. A method for producing an excellent conductive filler, a conductive addition reaction-curable silicone composition having excellent thermal stability of a cured product of a curable silicone composition containing the conductive filler, and a semiconductor element using the composition. An object of the present invention is to provide a semiconductor device which is coated and cured and has excellent reliability.

This object is achieved by the following.
[1] A method for producing a conductive filler, comprising treating a conductive particle having a surface coated with a fatty acid with an epoxy group-containing organoalkoxysilane, and further treating the surface with an organosilazane.
[1-1] The method according to [1], wherein the epoxy group-containing organoalkoxysilane is the epoxy group-containing organoalkoxysilane itself or an organic solvent solution thereof, and the organosilazane is the organosilazane itself or an organic solvent solution thereof. A method for producing the conductive filler according to the above.
[1-2] The method for producing a conductive filler according to [1-1], wherein the organic solvent for the epoxy group-containing organoalkoxysilane is an anhydrous alcohol.
[1-3] The epoxy group-containing organoalkoxysilane is partially hydrolyzed and condensed, and the partially hydrolyzed condensate coating coats conductive particles whose surface is coated with a fatty acid. The method for producing a conductive filler according to [1-2].
[1-4] The method for producing a conductive filler according to [1], [1-2] or [1-3], wherein the treatment with the organosilazane is a hydrophobic treatment.
[2] The surface treatment of the conductive particles whose surfaces are coated with a fatty acid with the epoxy group-containing organoalkoxysilane is performed by combining the conductive particles whose surface is coated with the fatty acid with the epoxy group-containing organoalkoxysilane itself or an organic solvent solution thereof. The method for producing a conductive filler according to claim 1, wherein the method comprises mixing and separating the surface-treated conductive particles from the mixture.
[3] The conductive particles are conductive metal particles, the epoxy group-containing organoalkoxysilane is glycidoxyalkyl trialkoxysilane or 2- (3,4-epoxycyclohexyl) alkyl trialkoxysilane, and the organosilazane is hexagonal. The method for producing a conductive filler according to [1] or [2], which is an organodisilazane.
[3-1] The conductive particles are conductive metal particles, the epoxy group-containing organoalkoxysilane is glycidoxyalkyl (methyl) dialkoxysilane, and the organosilazane is hexaorganodisilazane. , [1] or the method for producing a conductive filler according to [2].
[4] The conductive metal particles are silver particles, the glycidoxyalkyl trialkoxysilane is 3-glycidoxypropyltrimethoxysilane or 3-glycidoxypropyltriethoxysilane, and the hexaorganodisilazane is hexamethyl. The method for producing a conductive filler according to [3], which is disilazane.

[5] A conductive additive, wherein the conductive particles whose surfaces are coated with a fatty acid are surface-treated with an epoxy group-containing organoalkoxysilane, and further include the conductive particles treated with an organosilazane. Reaction-curable silicone composition.
[5-1] The conductive addition reaction-curable silicone composition according to [5], wherein the composition contains the conductive particles in an amount of 30 to 95% by mass.
[5-2] The conductive addition reaction-curable silicone composition according to [5] or [5-1], wherein the conductive addition reaction-curable silicone composition is a conductive addition reaction-curable silicone elastomer composition.
[5-3] the surface treatment with an epoxy group-containing organoalkoxysilane is coating with a partially hydrolyzed condensate of the epoxy group-containing organoalkoxysilane, and the treatment with the organosilazane is a hydrophobic treatment. The conductive addition reaction-curable silicone composition according to [5], [5-1] or [5-2].
[6] The conductive particles are conductive metal particles, the epoxy group-containing organoalkoxysilane is glycidoxyalkyl trialkoxysilane or 2- (3,4-epoxycyclohexyl) alkyl trialkoxysilane, and the organosilazane is hexagonal. The conductive addition reaction-curable silicone composition according to [5], [5-1], [5-2] or [5-3], which is an organodisilazane.
[7] The conductive metal particles are silver particles, the glycidoxyalkyl trialkoxysilane is 3-glycidoxypropyltrimethoxysilane or 3-glycidoxypropyltriethoxysilane, and the hexaorganodisilazane is hexamethyl. The conductive addition reaction-curable silicone composition according to [6], which is disilazane.
[8] The addition reaction-curable silicone composition constituting the conductive addition reaction-curable silicone composition comprises (A) a liquid organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule, and (B) silicon. The conductive material according to any one of [5] to [7], comprising: a liquid organopolysiloxane having at least two atom-bonded hydrogen atoms in one molecule; and (C) an addition reaction catalyst. An addition reaction-curable silicone composition.
[9] The conductive addition reaction-curable silicone composition according to [8], further comprising (D) an addition reaction control agent, and (E) an adhesion-imparting agent.

[10] A conductive addition reaction-curable silicone elastomer composition comprising conductive particles whose surfaces are coated with a fatty acid, the surface of which is treated with an epoxy group-containing organoalkoxysilane, and further containing the conductive particles treated with an organosilazane. A semiconductor device, wherein a semiconductor element is covered with a cured product.
[11] The semiconductor device according to [10], wherein the semiconductor element is bonded to a heat sink via a cured product of the conductive addition-curable silicone elastomer composition according to [10]. .

According to the method for producing a conductive filler of the present invention, a conductive filler capable of imparting excellent conductivity and storage stability to a non-curable silicone composition and a curable silicone composition can be easily and efficiently produced. can do.
The conductive addition reaction-curable silicone composition containing the conductive filler produced by the production method of the present invention is excellent in storage stability, so that the viscosity increase during storage is small, and the cured product is thermally stable. Is effective. Further, the semiconductor device of the present invention has an effect of having excellent reliability because the semiconductor element is covered with the cured product of such a conductive addition-curable silicone elastomer composition.

1 is a cross-sectional view of an LSI which is an example of a semiconductor device according to the present invention.

The method for producing a conductive filler according to the present invention is characterized in that the surface of conductive particles coated with a fatty acid is treated with an epoxy group-containing organoalkoxysilane, and further treated with an organosilazane.

The material of the conductive particles may be any material having excellent conductivity, such as gold, silver, copper, palladium, aluminum, nickel, tin and alloys thereof; silica, glass, silicon nitride, boron nitride, Inorganic substances such as silicon carbide; and metal compounds such as aluminum nitride, alumina, titanium oxide, aluminum hydroxide, and aluminum sulfide are exemplified, but silver particles are preferable in terms of conductivity. The silver particles may be any of reduced silver, atomized silver, electrolytic silver, and the like, but are preferably reduced silver particles produced by a metal salt reduction method, particularly a wet reduction method. Note that metal particles such as silver particles have excellent electrical conductivity and thermal conductivity.

The shape of the conductive particles is, for example, spherical, granular, teardrop-like, flake-like, plate-like, fibrous, columnar, crushed, or coil-like, but is spherical, granular, teardrop-like, or flake-like. Is preferred. The average particle diameter is not particularly limited as long as it is in the form of fine particles, but the average particle diameter (median diameter D50) is preferably 0.01 to 50 μm, more preferably 0.1 to 5 μm.
When the average particle size exceeds 50 μm, the conductivity of the conductive addition-curable silicone composition of the present invention may not be sufficiently obtained. When the average particle size is less than 0.01 μm, the surface activity is too strong and the storage stability is high. Is likely to decrease.
The average particle size is a 50% integrated volume-based value of the particle size distribution measured using a laser diffraction / scattering type particle size distribution analyzer, that is, a median diameter (D50 value).

The fatty acid that coats the surface of the conductive particles is not particularly limited, and may be a saturated fatty acid or an unsaturated fatty acid, but preferably has 6 or more carbon atoms, and more preferably 16 or more from the viewpoint of dispersibility. More preferred. Examples of fatty acids having 6 or more carbon atoms include caproic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and linoleic acid. Incidentally, a polyvalent carboxylic acid may be used in combination as long as the purpose is not adversely affected.

When the conductive metal particles are produced by a wet reduction method of a metal salt, a fatty acid is usually added during the production process to prevent agglomeration, so that the reduced metal particles (eg, reduced silver particles) are fatty acids. It is coated (for example, JP-A-54-121270).
In addition, even if the fatty acid is not added at the time of production by the wet reduction method, or if the fatty acid is added and the reduced metal particles are coated with the fatty acid, the reduced metal particles produced in such a manner (eg, reduced silver) Fatty acids may be added to the particles) later.
The post-addition method is a method in which a liquid or powdered fatty acid is directly mixed with reduced metal particles (eg, reduced silver particles), or a method in which the fatty acid is dissolved in a soluble volatile solvent, and the reduced silver particles are added to the solution. A method of removing the volatile solvent after the addition is exemplified. When the conductive metal particles are in the form of flakes, when the conductive metal particles are flaked by a ball mill or the like, a fatty acid as a lubricant or a lubricant is added to prevent aggregation of the particles. Have been done. Examples of the method of addition include a method of adding a fatty acid in the form of a liquid, powder, or solution with a volatile solvent.

In the method for producing conductive particles according to the first aspect, first, the surface of the conductive particles coated with a fatty acid is treated with an epoxy group-containing organoalkoxysilane. The epoxy group-containing organoalkoxysilane has three or two alkoxy groups bonded to a silicon atom. Examples of the alkoxy group include a lower alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group, and particularly preferably a methoxy group having excellent reactivity and then an ethoxy group. Further, the epoxy group is preferably an epoxy group in a glycidoxyalkyl group (preferably, a glycidoxypropyl group).

Examples of such epoxy group-containing organoalkoxysilanes include glycidoxyalkyl trialkoxysilane, glycidoxypropyl (methyl) dialkoxysilane, and 2- (3,4-epoxycyclohexyl) alkyl trialkoxysilane. Examples of glycidoxyalkyl trialkoxysilane include 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane, and examples of glycidoxypropyl (methyl) dialkoxysilane include 3-glycidoxypropyl (methyl). ) Dimethoxysilane, and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane as 2- (3,4-epoxycyclohexyl) alkyl trialkoxysilane, but 3-glycidoxypropyltrimethoxy It is preferably silane or 3-glycidoxypropyltriethoxysilane.

As described above, the conductive filler of the present invention can be produced by subjecting the conductive particles whose surfaces are coated with a fatty acid to a surface treatment with an epoxy group-containing organoalkoxysilane, and further treating with an organosilazane. .
In order to surface-treat the conductive particles whose surfaces are coated with a fatty acid with an epoxy group-containing organoalkoxysilane, the epoxy group-containing organoalkoxysilane is usually in a liquid state at room temperature. The conductive particles, the surfaces of which are coated with a fatty acid, are immersed in an organic solvent solution, stirred well, and then allowed to stand to take out the separated conductive particles. Alternatively, the epoxy group-containing organoalkoxylan itself or an organic solvent solution thereof is thoroughly mixed with the conductive particles whose surfaces are coated with a fatty acid, and the mixture is allowed to stand to take out the separated conductive particles.

The organic solvent for dissolving the epoxy group-containing organoalkoxylan is a liquid at ordinary temperature, and is preferably a volatile one. Alcohols (eg, ethanol, propanol), ketones (eg, acetone, methyl ethyl ketone), esters (eg, ethyl acetate), aliphatic hydrocarbon solvents (eg, octane, cyclohexane), aromatic hydrocarbon solvents (eg, toluene) , Xylene).
When ethanol is used as an organic solvent for dissolving an organoalkoxylan containing an epoxy group, even a small amount of water (for example, 0.1% by volume) can be contained in anhydrous ethanol (more than 99.5% by volume of ethanol) in the Japanese Pharmacopoeia. Therefore, the organoalkoxylan containing an epoxy group is partially hydrolyzed to generate a partially hydrolyzed condensate, which adheres to the surface of the conductive particles whose surface is coated with a fatty acid. The conductive particles whose surfaces are coated with a fatty acid are coated with a coating of a partially hydrolyzed condensate of an organoalkoxylan containing an epoxy group.
As a result, anhydrous ethanol is a preferred organic solvent because the surface treatment effect is improved. The water content of anhydrous ethanol is preferably 0.05 to 0.3% by volume.

A step of immersing the conductive particles, the surface of which is coated with a fatty acid, in an epoxy group-containing organoalkoxylan itself or an organic solvent solution thereof, followed by stirring, or the epoxy group-containing organoalkoxylan itself or an organic solvent solution thereof, and The step of mixing with the conductive particles coated with the fatty acid may be performed at room temperature in an air atmosphere, or may be performed by heating to about 40 to 100 ° C. The stirring time and the mixing time are preferably from 5 minutes to 10 hours.
The conductive particles removed by settling are preferably dried by air drying or vacuum drying, etc., and rinsed with a clean organic solvent before drying to remove excess epoxy group-containing organoalkoxysilane attached to the surface. It may be removed.

The conductive particles, the surface of which has been treated with an epoxy group-containing organoalkoxysilane and whose surface is coated with a fatty acid, are further treated with an organosilazane.
Organosilazane is a general term for organosilicon compounds having a Si-N bond in the molecule, and organodisilazane and organotrisilazane are preferred. Hexamethyldisilazane, sym-tetramethyldivinyldisilazane, octamethyltrisilazane, and hexamethylcyclotrisilazane are exemplified, but hexamethyldisilazane is preferred in terms of reactivity and availability.

In particular, hexamethyldisilazane is a well-known trimethylsilyl group donor, and is a compound having an active hydrogen (eg, a silanol group-containing compound, a carboxylic acid, an alcohol, an organic amine, or a phenol) that is subjected to trimethylsiloxylation or trimethylsilylation to impart hydrophobicity. It is known to have a gender effect.
Therefore, when the conductive particles, the surface of which has been treated with an epoxy group-containing organoalkoxysilane and the surface of which is coated with a fatty acid, are further treated with hexamethyldisilazane, the silanol in the partially hydrolyzed condensate of the epoxy group-containing organoalkoxysilane is obtained. Groups can be trimethylsilylated to make them hydrophobic. As a result, the silanol groups in the partially hydrolyzed condensate of the epoxy group-containing organoalkoxylan, which covers the conductive particles whose surfaces are coated with the fatty acid, become trimethylsiloxy groups.
If there is a fatty acid remaining in a free state, the carboxyl group in the fatty acid can be trimethylsilylated to make it hydrophobic. Therefore, the organosilazane treatment can be called a hydrophobic treatment.

The method of treating the conductive particles, the surface of which has been treated with an epoxy group-containing organoalkoxysilane, the surface of which is coated with a fatty acid, further with an organosilazane, comprises the steps of: It can be carried out according to the method of surface treatment with alkoxysilane.

When the organosilazane is liquid at room temperature, the organosilazane itself can be used as it is, but from the viewpoint of processing efficiency, it is preferable to use a solution obtained by diluting the organosilazane with an organic solvent. The organic solvent for this purpose is preferably a liquid that is liquid at ordinary temperature, is volatile, and has no active hydrogen. Ketones (eg, acetone, methyl ethyl ketone), esters (eg, ethyl acetate), aliphatic hydrocarbon solvents (eg, octane, cyclohexane), and aromatic hydrocarbon solvents (eg, toluene, xylene) are exemplified. Alcohols are not preferred because they have active hydrogen and react with organosilazanes.
Moreover, ordinary ethanol is not preferable because it contains about 5% by volume of water and the organosilazane is hydrolyzed.

Then, the conductive particles, the surface of which has been treated with an epoxy group-containing organoalkoxysilane, the surface of which is coated with a fatty acid, are immersed in the organosilazane itself or its organic solvent solution, stirred well, allowed to stand, and sedimented. Then, the target conductive particles are taken out. Alternatively, the desired product is obtained by thoroughly mixing the conductive particles, the surface of which has been treated with an epoxy group-containing organoalkoxysilane, the surface of which is coated with a fatty acid, and the organosilazane itself or an organic solvent solution thereof, and then allowing it to stand to separate by settling. Take out the conductive particles.

A step of immersing the conductive particles, the surface of which has been treated with an epoxy group-containing organoalkoxysilane, coated with a fatty acid, in an organosilazane itself or an organic solvent solution thereof, or a step of treating the surface with an epoxy group-containing organoalkoxysilane. The step of mixing the conductive particles whose surfaces are coated with a fatty acid and the organosilazane itself or an organic solvent solution thereof may be performed at room temperature in an air atmosphere, or by heating to about 40 to 100 ° C. Is also good. The stirring time and the mixing time are preferably from 5 minutes to 10 hours.
The conductive particles, which are the target substance, which are separated and settled out, are preferably dried by air drying or vacuum drying, and rinsed with a clean organic solvent before drying to remove excess ornosilazane adhering to the surface. It may be removed.

The conductive filler produced by the production method of the present invention is a curable silicone composition (for example, an addition reaction-curable silicone rubber composition, an organic peroxide-curable silicone rubber composition, and a room temperature-curable silicone rubber composition). ), And is useful as a filler for imparting conductivity to a non-curable silicone composition (for example, a silicone oil compound).
In particular, it is useful as a conductive filler to be added to a liquid or paste-like addition reaction-curable silicone composition, particularly an addition reaction-curable silicone elastomer composition. The compounding amount varies depending on the conductivity, specific gravity, desired conductivity and the like, but is usually 30 to 95% by mass, preferably 60 to 90% by mass in the silicone composition.

In the conductive addition reaction-curable silicone composition of the present invention, the silicone composition serving as the base material is preferably an addition reaction-curable silicone composition. The addition reaction curing type is also called a hydrosilylation reaction curing type. Particularly, from the viewpoint of workability, it is preferable that the addition-curable silicone composition is liquid or paste at room temperature.
Such an addition reaction-curable silicone composition comprises (A) a liquid organopolysiloxane having at least two silicon-bonded alkenyl groups in one molecule, and (B) at least two silicon-bonded hydrogen atoms in one molecule. Liquid organopolysiloxane having (C) an addition reaction catalyst as essential components, and further containing (D) an addition reaction control agent and (E) an adhesion-imparting agent, thereby increasing the viscosity due to the addition reaction at room temperature. A sufficient addition time can be ensured by suppressing the addition, and an addition reaction-curable silicone composition having excellent adhesiveness to a substrate that is in contact with the substrate during curing can be obtained.

The conductive addition reaction-curable silicone composition of the present invention is obtained by mixing components (A) to (C), components (A) to (D), or components (A) to (E) with a mixer or the like. Can be easily manufactured. The temperature at the time of mixing is preferably room temperature, for example, 30 ° C. or lower and a temperature at which no dew condensation occurs so that the addition reaction does not proceed during the mixing.

The component (A) is a main component of the conductive addition-curable silicone composition of the present invention, and the silicon-bonded alkenyl group undergoes an addition reaction with the silicon-bonded hydrogen atom in the component (B) to crosslink. Therefore, when the number of silicon-bonded alkenyl groups in component (A) is two, the number of silicon-bonded hydrogen atoms in component (B) is three or more, and the number of silicon-bonded hydrogen atoms in component (B) is two or more. In this case, the number of silicon-bonded alkenyl groups in the component (A) is preferably 3 or more.
The molecular structure of the component (A) is exemplified by a straight chain, a partially branched straight chain, a branched chain, a ring, and a network, and a rubber or gel having elasticity after curing, that is, an elastomer. In order to obtain a straight chain, a straight chain or a straight chain partially having a branch is preferable.

Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a pentenyl group, and a hexenyl group, and a vinyl group is generally used.
The bonding position of the silicon-bonded alkenyl group in the component (A) includes a molecular chain terminal, a molecular chain side chain, and both.

Examples of the silicon atom-bonding group other than the alkenyl group in the component (A) include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group and a heptyl group; a phenyl group, a tolyl group, and a xylyl group. Aralkyl groups such as benzyl and phenethyl groups; unsubstituted or substituted monovalent hydrocarbons such as halogenated alkyl groups such as 3-chloropropyl group and 3,3,3-trifluoropropyl group. Groups are exemplified. Among them, a methyl group is most common because it can be easily produced industrially, and then both a methyl group and a phenyl group are common.

The viscosity of the component (A) at 25 ° C. is preferably from 10 to 100,000 mPa · s, more preferably from 100 to 10,000 mPa · s, from the viewpoint of the handleability of the composition and the physical properties after curing. When the viscosity of the component (A) is lower than 10 mPa · s, the mechanical strength of the cured product tends to be insufficient. When the viscosity is higher than 100,000 mPa · s, the cured product is too viscous and is in a liquid or paste state. This is because it is difficult to obtain a conductive addition reaction-curable silicone composition.

Representative examples of the component (A) include dimethylpolysiloxane or a dimethylsiloxane / methylvinylsiloxane copolymer having dimethylvinylsiloxy groups at both ends, a dimethylsiloxane / methylvinylsiloxane copolymer having trimethylsiloxy groups at both ends, and a dimethylvinylsiloxy group at both ends. There are straight-chain dimethylpolysiloxane blocked with a trimethylsiloxy group, branched methylpolysiloxane blocked with a dimethylvinylsiloxy group and a trimethylsiloxy group, and polysiloxane in which a part of the methyl group of the above polysiloxane is substituted with a phenyl group. Two or more components (A) may be used in combination.

The component (B) is a crosslinking agent for the addition reaction of the component (A), and its silicon-bonded hydrogen atom undergoes an addition reaction with the silicon-bonded alkenyl group in the component (A) to crosslink.
The molecular structure of the component (B) is exemplified by a straight chain, a partially branched straight chain, a branched chain, and a network. The bonding position of the silicon-bonded hydrogen atom includes a molecular chain terminal, a molecular chain side chain, and both. Examples of the group bonded to a silicon atom other than a hydrogen atom in the component (B) include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group and a heptyl group; a phenyl group, a tolyl group; Xylyl groups, naphthyl groups and the like; substituted or unsubstituted monovalent hydrocarbon groups such as halogenated alkyl groups such as 3-chloropropyl group and 3,3,3-trifluoropropyl group. Methyl groups are most common, followed by both methyl and phenyl groups.

The viscosity of the component (B) at 25 ° C. is preferably in the range of 0.1 to 10,000 mPa · s, and more preferably in the range of 1 to 1,000 mPa · s. As typical examples, methylhydrogenpolysiloxane having a trimethylsiloxy group at both ends or a dimethylsiloxy group at both ends (that is, methyl hydrogen polysiloxane), and dimethylsiloxane / methylhydrogen having a trimethylsiloxy group at both ends or a dimethylsiloxy group at both ends There are siloxane copolymers, cyclic methylhydrogensiloxane oligomers, and tetrakis (dimethylhydrogensiloxy) silane. (B) Two or more components may be used in combination.

The compounding amount of the component (B) may be a sufficient amount to crosslink the component (A) to form a rubber or gel, and the silicon-bonded hydrogen atom and the silicon-bonded alkenyl group in the component (A) may be mixed. The amount which makes the molar ratio of 0.3 to 5 is exemplified. When the cured product is in a gel form, it is preferably from 0.3 to 0.8, and when the cured product is in a rubber form, it is preferably from 0.8 to 5. Even at the same molar ratio, the weight ratio of the components (A) and (B) differs depending on the molecular weight of the component (A) and the content of the silicon-bonded alkenyl group and the molecular weight of the component (B) and the content of the silicon-bonded hydrogen atom. Therefore, the blending amount of the component (B) per 100 parts by mass of the component (A) cannot be specified, but is usually 1 to 30 parts by mass.

The component (C) is a catalyst for accelerating the addition reaction between the silicon-bonded alkenyl group in the component (A) and the silicon-bonded hydrogen atom in the component (B), that is, a catalyst for the addition reaction. Catalysts, rhodium catalysts and palladium catalysts are exemplified.
Platinum catalysts are preferred in terms of performance and availability. Platinum fine powder, platinum-supported silica fine powder, platinum-supported activated carbon, chloroplatinic acid, alcohol-modified chloroplatinic acid, diolefin complex of platinum, diketone complex of platinum , Platinum dialkenyltetraalkyldisiloxane complexes, and thermoplastic resin fine particles containing these platinum-based catalysts.
The component (C) is added in a catalytic amount, that is, an amount sufficient to cause a hydrosilation reaction between the silicon-bonded alkenyl group in the component (A) and the silicon-bonded hydrogen atom in the component (B). In the case of a platinum-based catalyst, the amount of platinum atoms in the catalyst is generally 0.1 to 100 ppm by mass in the composition. Two or more components (C) may be used in combination.

The (D) addition reaction controlling agent controls the addition reaction rate between the silicon-bonded alkenyl group in the component (A) and the silicon-bonded hydrogen atom in the component (B) to suppress curing at room temperature. The purpose is to cure rapidly under heating. Alkyne alcohols such as 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol and phenylbutynol; 3-methyl-3-penten-1-yne, 3,5 Eneyne compounds such as -dimethyl-3-hexen-1-yne; 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetramethyl Examples thereof include -1,3,5,7-tetrahexenylcyclotetrasiloxane and benzotriazole. The amount of the component (D) is usually 0.01 to 5 parts by mass based on 100 parts by weight of the component (A). By containing the component (D) in addition to the component (A), the component (B) and the component (C), the silicone composition can be made to be thermosetting with excellent workability which does not easily thicken at room temperature. .

(E) The adhesion-imparting agent is preferably an organosilane or an organosiloxane oligomer having at least two silicon-bonded alkenyl groups or at least two alkoxy groups having at least one hydrogen atom bonded to the same silicon atom. Examples of the molecular structure of the organosiloxane oligomer include linear, partially branched linear, branched, and cyclic. Examples of the silicon-bonded alkenyl group in this component include a vinyl group, an allyl group, a butenyl group, a pentenyl group, and a hexenyl group, and a vinyl group is particularly preferable. Examples of the silicon-bonded alkoxy group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and a methoxyethoxy group, and a methoxy group bonded to the same silicon atom is preferable. Examples of the silicon atom-bonding group other than the alkenyl group and the alkoxy group include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group and a heptyl group; a phenyl group, a tolyl group, a xylyl group and a naphthyl group. Aryl groups such as benzyl group and phenethyl group; halogenated alkyl groups such as 3-chloropropyl group and 3,3,3-trifluoropropyl group; 3-glycidoxypropyl group and 4-glycidyl A glycidoxyalkyl group such as a xybutyl group; a (3,4-epoxycyclohexyl) alkyl group such as a 2- (3,4-epoxycyclohexyl) ethyl group or a 3- (3,4-epoxycyclohexyl) propyl group; Oxiranylalkyl groups such as -oxiranylbutyl group and 8-oxiranyloctyl group are exemplified. It is preferable to have at least one epoxy group-containing monovalent organic group in one molecule, since good adhesion can be imparted to various substrates that are in contact when the composition is cured.

Examples of the adhesion-imparting agent include vinyltrimethoxysilane, allyltrimethoxysilane, hydrogen entrymethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, A partial condensate of glycidoxypropyltrimethoxysilane and a dimethylsiloxane oligomer having silanol groups at both ends, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane and a dimethylsiloxane oligomer having silanol groups at both ends. There is a partial condensate of
The adhesion-imparting agent is liquid at ordinary temperature, and preferably has a viscosity at 25 ° C. of 1 to 500 mPa · s. The compounding amount is usually 0.1 to 5 parts by mass with respect to 100 parts by mass of the component (A).

The conductive addition reaction-curable silicone composition is preferably a paste at room temperature and thermosetting from the viewpoint of workability during use. The cured product is preferably in the form of a rubber or a gel (a so-called semi-cured state in which a part is crosslinked). The conductive addition reaction-curable silicone composition of the present invention may have thermal conductivity at the same time.

The amount of the conductive filler in the conductive addition-curable silicone composition of the present invention varies depending on its conductivity, specific gravity, desired conductivity, and the like, but is usually 30 to 95% by mass in the composition. And preferably 60 to 90% by mass. By uniformly mixing the addition reaction type silicone composition and the conductive filler with a mixer or the like, a conductive addition reaction curing type silicone composition can be easily produced. The temperature at the time of mixing is preferably room temperature, for example, 30 ° C. or lower, and a temperature at which no dew condensation occurs, so that the addition reaction of the addition reaction type silicone composition does not proceed during the mixing.

In the conductive addition reaction-curable silicone composition of the present invention, a reinforcing filler (for example, fumed silica), an extending filler (for example, quartz powder), a solvent, a coloring agent, Additives such as flame retardants and non-reactive silicone oils may be blended.

The conductive addition reaction-curable silicone composition of the present invention is useful as an adhesive for electric / electronic parts, a sealing agent, a potting agent, a protective coating agent, and the like, and also as an adhesive between a semiconductor element and a heat sink. Useful. The addition reaction-curable silicone composition comprising the above components (A) to (C) cures even at room temperature, but the addition reaction-curable silicone composition comprising the components (A) to (D) at room temperature. Does not easily increase the viscosity, and rapidly cures under heating. The heating temperature is preferably in the range of 50 to 250C, more preferably in the range of 100 to 200C.

In the semiconductor device of the present invention, the semiconductor element is covered with a cured product of the conductive addition reaction-curable silicone elastomer composition of the present invention. A part of the semiconductor element may be covered, or the whole may be covered. The semiconductor element may be bonded to another member (for example, a heat sink) via a cured product of the above-described conductive addition reaction-curable silicone elastomer composition. Examples of the semiconductor element include a diode, a transistor, a thyristor, a monolithic IC, or a semiconductor element in a hybrid IC. Examples of the semiconductor device include a diode, a transistor, a thyristor, a monolithic IC, a hybrid IC, an LSI, a VLSI, and an IGBT.

FIG. 1 is a sectional view of an LSI which is an example of the semiconductor device of the present invention. In the LSI of FIG. 1, a semiconductor element 4 is mounted on a circuit board 1, and the semiconductor element 4 and a wiring 2 connected to an external lead are electrically connected by a gold electrode (bump) 3. . A radiator plate 6 is placed on the back surface of the semiconductor element 4, and a conductive silicone rubber 5 which is a cured product of a conductive addition-curable silicone rubber composition exists between the semiconductor element 4 and the radiator plate 6. The conductive silicone rubber 5 adheres well to both the semiconductor element 1 and the heat sink 6. Since the conductive silicone rubber 5 also has thermal conductivity, heat generated by the semiconductor element 4 can be efficiently dissipated through the heat sink 6.

Examples of the material of the circuit substrate 1 include organic resins such as polyimide resin, bismaleimide triazine resin, glass fiber reinforced epoxy resin, bakelite resin, and phenol resin; ceramics; and metals such as copper and aluminum. Examples of the material of the wiring 2 include gold, copper, and silver-palladium. As a material other than gold in the gold electrode (bump) 3, a gold alloy is exemplified. Examples of the material of the heat radiating plate 6 include metals having good conductivity such as aluminum, copper, and nickel. In addition to the semiconductor element 4, electronic components such as a resistor, a capacitor, and a coil may be mounted on the circuit board 1.

In order to manufacture the semiconductor device of the present invention, for example, the semiconductor element 4 is mounted on the circuit board 1, and then the semiconductor element 4 and the wiring 2 printed on the circuit board 1 are connected to a gold electrode ( After the electrical connection by the bumps 3, the conductive addition reaction-curable silicone rubber composition 5 of the present invention is applied on the back surface of the semiconductor element 4, and a heat sink 6 is placed thereon, And heat to cure.

Examples The conductive filler, the conductive addition-curable silicone rubber composition, and the semiconductor device manufactured by the manufacturing method of the present invention will be described in more detail with reference to examples. In addition, the viscosity in an Example is a value measured at 25 degreeC. Further, the storage stability of the conductive addition reaction-curable silicone rubber composition, the volume resistivity of the cured product of the conductive addition reaction-curable silicone rubber composition, and the hardness of the cured product of the conductive addition reaction-curable silicone rubber composition. The thermal stability and reliability of the semiconductor device were measured as follows.

[Storage stability of conductive addition reaction-curable silicone rubber composition]
The conductive addition reaction-curable silicone rubber composition in the form of a paste was placed in a 100-ml glass bottle, the temperature was adjusted at 25 ° C. for 30 minutes, and the value measured by a rotary viscometer using a spindle was defined as the initial viscosity. The number of rotations at that time was appropriately selected depending on the viscosity of the paste-like conductive addition reaction-curable silicone rubber composition. After this measurement, the glass bottle was capped with a lid, stored in an atmosphere at 25 ° C. for 100 hours, and the viscosity was measured in the same manner. The smaller the difference between the initial viscosity and the viscosity after storage for 100 hours, the better the storage stability.

[Volume resistivity of cured product of conductive addition reaction-curable silicone rubber composition]
The conductive addition reaction-curable silicone rubber composition in the form of a paste is poured into a mold having a length of 5 cm × 5 cm and a depth of 2 mm, and is heated and cured in a hot-air circulating oven at 150 ° C. for 1 hour, according to JIS K 7194. The volume resistivity (unit: Ω · cm) was measured by a method according to the above.

[Heat stability of hardness of cured product of conductive addition reaction-curable silicone rubber composition]
The conductive addition reaction-curable silicone rubber composition in the form of a paste is poured into the mold and heated in a hot-air circulating oven at 150 ° C. for one hour to form a stack of three conductive silicone rubber sheets. The hardness was measured using a hardness tester (type A durometer) according to JIS K 6253 for a sample having a thickness of 6 mm. Next, this rubber sheet was heated and aged for 24 hours in a hot air circulating oven at 150 ° C. in the atmosphere, and then the hardness was measured using a hardness tester (type A durometer) according to JIS K6253. The smaller the difference between the initial hardness and the hardness after aging, the better the thermal stability.

[Reliability of semiconductor device]
The semiconductor device shown in FIG. 1 was produced. That is, after the semiconductor element 4 is mounted on the circuit board 1 made of glass fiber reinforced epoxy resin having the wiring 2 formed by printing on the surface and the external leads at the ends, the semiconductor element 4 and the wiring 2 are made of gold. (Electrode) 3 (electric bump). After a paste-like conductive addition reaction-curable silicone rubber composition is applied on the back surface of the semiconductor element 4 by a dispenser, an aluminum radiator plate 6 is attached and immediately in a hot-air circulation oven at 150 ° C. in the atmosphere. By heating, ten semiconductor devices in which the semiconductor element 4 and the heat radiating plate 6 were bonded by the cured product 5 of the conductive addition reaction-curable silicone rubber composition were produced.
The semiconductor device thus manufactured is subjected to 100 thermal cycle tests at -40.degree. C. for 30 minutes and + 150.degree. C. for 30 minutes, and then the conductivity between the semiconductor element 4 and the heat sink 6 is increased. With respect to the cured product 5 of the reaction-curable silicone rubber composition, the presence or absence of peeling between the semiconductor element 4 and the heat sink 6 is observed with a microscope. (%) Was determined.

[Reference Example 1]
In a mixer, a solution of 1.0 g of 3-glycidoxypropyltrimethoxysilane in 300 g of ethanol (for research and experiment) (manufactured by Kanto Chemical Co., Ltd., water content: 0.1 v / v%) was used. 100 g of spherical silver particles A (average particle diameter of 1 μm) coated with an acid (oleic acid content: 0.3% by mass) were added, and the mixture was stirred at 70 ° C. for 3 hours. After the stirring, the spherical silver particles were allowed to settle by standing at room temperature for 10 minutes, then, the supernatant was extracted, and 300 g of the ethanol was added to the residue and stirred for 15 minutes. After stirring, the mixture was allowed to stand for 10 minutes to settle the spherical silver particles A, and then the supernatant was taken out, and the spherical silver particles A as a residue were air-dried at room temperature for 24 hours to coat the surface with oleic acid. Spherical silver particles A having an average particle diameter of 1 μm and having been surface-treated with 3-glycidoxypropyltrimethoxysilane were prepared.

When the supernatant was poured on a flat glass plate and spread and air-dried, a transparent, gel-like film was formed. When water was dropped on this gel-like coating, it did not repel water and became wet.
Since the starting material, 3-glycidoxypropyltrimethoxysilane, is a free-flowing, transparent liquid, it can be said that this gel-like coating consists of a partially hydrolyzed condensate of 3-glycidoxypropyltrimethoxysilane. it can. Therefore, in the spherical silver particles B, the spherical silver particles A whose surface is coated with oleic acid and have an average particle diameter of 1 μm are coated with a partially hydrolyzed condensate film of 3-glycidoxypropyltrimethoxysilane. It can be said that.

[Reference Example 2]
In the same manner as in Reference Example 1, except that 3-glycidoxypropyltriethoxysilane was used instead of 3-glycidoxypropyltrimethoxysilane, the average particle size of the surface of which was covered with oleic acid was 1 μm. Spherical silver particles C, which were certain spherical silver particles A and were surface-treated with 3-glycidoxypropyltriethoxysilane, were prepared.

In a mixer, a spherical surface treated with 3-glycidoxypropyltrimethoxysilane prepared in Reference Example 1 was prepared by dissolving 100 g of hexamethyldisilazane in 50 g of toluene (reagent first grade, manufactured by Kanto Chemical Co., Ltd.). 100 g of silver particles B were charged and stirred at 100 ° C. for 4 hours. After stirring, the mixture was allowed to stand at room temperature for 30 minutes to sediment the spherical silver particles B, and then the supernatant was extracted, and 50 g of hexane was added to the residue, followed by stirring for 2 hours. After stirring, the mixture was allowed to stand for 30 minutes to settle the spherical silver particles B, and then the supernatant was removed. The spherical silver particles B as a residue were dried at 50 ° C. and a degree of vacuum of 1333 Pa for 5 hours. The coated spherical silver particles A having an average particle diameter of 1 μm are subjected to a surface treatment with 3-glycidoxypropyltrimethoxysilane and further treated with hexamethyldisilazane to form conductive spherical silver particles D (conductive filler). ) Was prepared.

The glass plate on which the gel-like coating of Reference Example 1 was adhered was put into a solution in which 100 g of hexamethyldisilazane was dissolved in 50 g of toluene (manufactured by Kanto Kagaku Co., Ltd., first grade), and the solution was heated at 100 ° C. for 4 hours. Stirred. After stirring, the glass plate to which the gel-like coating was attached was taken out and air-dried. When water was dropped on the gel-like coating, the water was repelled. It was found that the gel-like coating became hydrophobic. It can be said that the silanol group in the partially hydrolyzed condensate of 3-glycidoxypropyltrimethoxysilane is a trimethylsiloxy group.
In the conductive spherical silver particles D, spherical silver particles A whose surface is coated with oleic acid and have an average particle diameter of 1 μm are coated with a partially hydrolyzed condensate film of 3-glycidoxypropyltrimethoxysilane. It can be said that the silanol group in the partial hydrolysis condensate is a trimethylsiloxy group.

In Example 1, instead of the spherical silver particles B treated with 3-glycidoxypropyltrimethoxysilane prepared in Reference Example 1, the surface treatment was performed with 3-glycidoxypropyltriethoxysilane prepared in Reference Example 2. In the same manner except that the obtained spherical silver particles C were used, spherical silver particles A whose surface was coated with oleic acid and had an average particle size of 1 μm were surface-treated with 3-glycidoxypropyltriethoxysilane, and further, Conductive spherical silver particles E (conductive filler) treated with hexamethyldisilazane were prepared.

で示される液状オルガノポリシロキサン１．３質量部を均一に混合して、粘度が３．９Ｐａ・ｓである、液状の付加反応硬化型シリコーンゴム組成物を調製した。
ついで、実施例１で調製した導電性球状銀粒子Ｄ９２質量部を加えて均一に混合して、粘度が１７２Ｐａ・ｓである、ペースト状の導電性付加反応硬化型シリコーンゴム組成物を調製した。In a mixer, (A) a linear dimethylpolysiloxane (A) having a viscosity of 5000 mPa · s and having both ends of a dimethylvinylsiloxy group and having a viscosity of 5000 mPa · s (the content of a vinyl group bonded to a silicon atom = 0.13 mass) %) 130 parts by mass, a cross-linking agent for addition reaction, (B) a dimethylsiloxane / methylhydrogensiloxane copolymer having a viscosity of 5 mPa · s and capped with trimethylsiloxy groups at both ends of a molecular chain (a hydrogen group bonded to a silicon atom) 3.4 parts by mass (content = 0.73% by mass), (C) 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex of platinum (C) as an addition reaction catalyst , The amount of platinum metal being 5 ppm by mass), and (D) 3-phenyl 1-butyn-3-ol (1 mass unit in the present composition) as an addition reaction control agent. The amount to be 00Ppm), and, as an adhesion-imparting agent, (E) represented by the following average unit formula:

Was uniformly mixed to prepare a liquid addition-curable silicone rubber composition having a viscosity of 3.9 Pa · s.
Next, 92 parts by mass of the conductive spherical silver particles D prepared in Example 1 were added and uniformly mixed to prepare a paste-like conductive addition reaction-curable silicone rubber composition having a viscosity of 172 Pa · s.

The storage stability of the conductive addition reaction-curable silicone rubber composition, the volume resistivity of the cured product, the thermal stability of the hardness of the cured product, and the fact that the semiconductor element and the heat sink are formed of the conductive addition reaction-curable silicone rubber composition. Table 1 summarizes the results of measuring the reliability of the semiconductor device bonded with the cured product of the silicone rubber composition. The conductive addition reaction-curable silicone rubber composition was found to have excellent storage stability, and the cured product was found to have excellent conductivity and thermal stability, and also to have excellent reliability in semiconductor devices.

In Example 3, in place of the conductive spherical silver particles D prepared in Example 1, the conductive spherical silver particles E prepared in Example 2 were used, and the viscosity was 166 Pa · s, a paste-like conductive addition reaction-curable silicone rubber composition was prepared.

The storage stability of the conductive addition reaction-curable silicone rubber composition, the volume resistivity of the cured product, the thermal stability of the hardness of the cured product, and the conductive silicone rubber composition comprising a semiconductor element and a radiator plate Table 1 summarizes the results of measuring the reliability of the semiconductor device bonded with the cured product of Example 1. The conductive addition reaction-curable silicone rubber composition was found to have excellent storage stability, and the cured product was found to have excellent conductivity and thermal stability, and also to have excellent reliability in semiconductor devices.

In Example 3, as the component (B), a dimethylsiloxane / methylhydrogensiloxane copolymer having a viscosity of 5 mPa · s and having both ends of a molecular chain and a trimethylsiloxy group blocked (content of hydrogen groups bonded to silicon atoms = 0. 73% by mass), a dimethylsiloxane / methylhydrogensiloxane copolymer having a viscosity of 5 mPa · s and capped with trimethylsiloxy groups at both ends of the molecular chain (content of hydrogen groups bonded to silicon atoms = 0.73% by mass) Except that 1.7 parts by mass and 2.8 parts by mass of a dimethylsiloxane blocked with dimethylhydrogen at both ends of the molecular chain having a viscosity of 5 mPa · s (content of hydrogen group bonded to silicon atom = 0.28% by mass) are used. In the same manner as in Example 3, a paste-like conductive addition reaction-curable silicone rubber composition having a viscosity of 189 Pa · s was prepared.

The storage stability of the conductive addition reaction-curable silicone rubber composition, the volume resistivity of the cured product, the thermal stability of the hardness of the cured product, and the fact that the semiconductor element and the heat sink are formed of the conductive addition reaction-curable silicone rubber composition. Table 1 summarizes the results of measuring the reliability of the semiconductor device bonded with the cured product of the silicone rubber composition. It has been found that this conductive addition reaction-curable silicone rubber composition has excellent storage stability, the cured product has excellent conductivity and thermal stability, and the semiconductor device has excellent reliability.

[Comparative Example 1]
In Example 3, in place of the spherical silver particles D prepared in Example 1, spherical silver particles whose surface was coated with oleic acid and having an average particle size of 1 μm (oleic acid content 0.3% by mass) ) A paste-like conductive addition reaction-curable silicone rubber composition having a viscosity of 158 Pa · s was prepared in the same manner as in Example 3 except that A was used.

The storage stability of the conductive addition reaction-curable silicone rubber composition, the volume resistivity of the cured product, the thermal stability of the hardness of the cured product, and the fact that the semiconductor element and the heat sink are formed of the conductive addition reaction-curable silicone rubber composition. Table 2 summarizes the results of measuring the reliability of the semiconductor device bonded with the cured product of the silicone rubber composition. It was found that the conductive addition reaction-curable silicone rubber composition had poor storage stability, the cured product had poor conductivity and thermal stability, and the reliability of the semiconductor device was low.

[Comparative Example 2]
In Example 3, except that the conductive spherical silver particles D prepared in Example 1 were replaced by spherical silver particles B surface-treated with 3-glycidoxypropyltrimethoxysilane prepared in Reference Example 1, In the same manner as in Example 3, a paste-like conductive addition reaction-curable silicone rubber composition having a viscosity of 162 Pa · s was prepared.

The storage stability of the conductive addition reaction-curable silicone rubber composition, the volume resistivity of the cured product, the thermal stability of the hardness of the cured product, and the fact that the semiconductor element and the heat sink are formed of the conductive addition reaction-curable silicone rubber composition. Table 2 summarizes the results of measuring the reliability of the semiconductor device bonded with the cured product of the silicone rubber composition. This conductive addition reaction-curable silicone rubber composition was found to have poor storage stability, although the cured product was relatively stable in conductivity and thermal stability.

[Comparative Example 3]
In Example 3, in place of the conductive spherical silver particles D prepared in Example 1, spherical silver particles C surface-treated with 3-glycidoxypropyltriethoxysilane prepared in Reference Example 2 were used. In the same manner as in Example 3, a paste-like conductive addition reaction-curable silicone rubber composition having a viscosity of 170 Pa · s was prepared.

The storage stability of the conductive addition reaction-curable silicone rubber composition, the volume resistivity of the cured product, the thermal stability of the hardness of the cured product, and the fact that the semiconductor element and the heat sink are formed of the conductive addition reaction-curable silicone rubber composition. Table 2 summarizes the results of measuring the reliability of the semiconductor device bonded with the cured product of the silicone rubber composition. This conductive addition reaction-curable silicone rubber composition was found to have poor storage stability, although the cured product was relatively stable in conductivity and thermal stability.

[Comparative Example 4]
In the same manner as in Reference Example 1, except that methyltrimethoxysilane was used instead of 3-glycidoxypropyltrimethoxysilane, spherical silver particles whose surface was coated with oleic acid and had an average particle size of 1 μm. Then, spherical silver particles F surface-treated with methyltrimethoxysilane were prepared.

[Comparative Example 5]
Example 3 was repeated except that the conductive spherical silver particles D prepared in Example 1 were replaced by spherical silver particles F prepared in Comparative Example 4 and surface-treated with methyltrimethoxysilane. Similarly, a paste-like conductive addition reaction-curable silicone rubber composition having a viscosity of 155 Pa · s was prepared.

The storage stability of the conductive addition reaction-curable silicone rubber composition, the volume resistivity of the cured product, the thermal stability of the hardness of the cured product, and the fact that the semiconductor element and the heat sink are formed of the conductive addition reaction-curable silicone rubber composition. Table 3 summarizes the results of measuring the reliability of the semiconductor device bonded with the cured product of the silicone rubber composition. It was found that the conductive addition reaction-curable silicone rubber composition had poor storage stability, and the cured product had relatively poor conductivity and thermal stability. The necessity of the epoxy group was confirmed.

1 circuit wiring board 2 wiring 3 gold electrodes (bumps)
4. Semiconductor elements (dummy elements)
5 Cured product of conductive addition-curable silicone rubber composition 6 Aluminum heat sink (cooling fin)

Industrial applications

The method for producing a conductive filler of the present invention is useful for producing a conductive filler capable of imparting excellent conductivity and storage stability to a non-curable silicone composition and a curable silicone composition. is there.
The conductive addition-curable silicone composition containing a conductive filler produced by the production method of the present invention is useful as an adhesive for electric / electronic parts, a sealing agent, a potting agent, a protective coating agent and the like. It is also useful as an adhesive between the semiconductor element and the heat sink.
The semiconductor device of the present invention is useful as a diode, transistor, thyristor, monolithic IC, hybrid IC, LSI, VLSI, IGBT, or the like.

Claims (11)

A method for producing a conductive filler, comprising treating a conductive particle having a surface coated with a fatty acid with an epoxy group-containing organoalkoxysilane, and further treating the surface with an organosilazane. Surface treatment of the conductive particles whose surfaces are coated with a fatty acid with an epoxy group-containing organoalkoxysilane is performed by mixing the conductive particles whose surfaces are coated with a fatty acid with the epoxy group-containing organoalkoxysilane itself or an organic solvent solution thereof, The method for producing a conductive filler according to claim 1, wherein the surface-treated conductive particles are separated from the mixture. The conductive particles are conductive metal particles, the epoxy group-containing organoalkoxysilane is glycidoxyalkyl trialkoxysilane or 2- (3,4-epoxycyclohexyl) alkyl trialkoxysilane, and the organosilazane is hexaorganodisilazane. The method for producing a conductive filler according to claim 1, wherein: The conductive metal particles are silver particles, glycidoxyalkyl trialkoxysilane is 3-glycidoxypropyltrimethoxysilane or 3-glycidoxypropyltriethoxysilane, and hexaorganodisilazane is hexamethyldisilazane. The method for producing a conductive filler according to claim 3, wherein: Conductive addition reaction-curable type, characterized in that conductive particles whose surfaces are coated with a fatty acid are surface-treated with an epoxy group-containing organoalkoxysilane and further contain conductive particles that are treated with an organosilazane. Silicone composition. The conductive particles are conductive metal particles, the epoxy group-containing organoalkoxysilane is glycidoxyalkyl trialkoxysilane or 2- (3,4-epoxycyclohexyl) alkyl trialkoxysilane, and the organosilazane is hexaorganodisilazane. The conductive addition reaction-curable silicone composition according to claim 5, wherein: The conductive metal particles are silver particles, glycidoxyalkyl trialkoxysilane is 3-glycidoxypropyltrimethoxysilane or 3-glycidoxypropyltriethoxysilane, and hexaorganodisilazane is hexamethyldisilazane. The conductive addition reaction-curable silicone composition according to claim 6, wherein The addition reaction-curable silicone composition constituting the conductive addition reaction-curable silicone composition comprises (A) a liquid organopolysiloxane having at least two silicon-bonded alkenyl groups in one molecule, and (B) a silicon-bonded hydrogen. The conductive addition according to any one of claims 5 to 7, comprising a liquid organopolysiloxane having at least two atoms in one molecule, and (C) an addition reaction catalyst. Reaction-curable silicone composition. 9. The conductive addition reaction-curable silicone composition according to claim 8, further comprising (D) an addition reaction control agent and (E) an adhesion-imparting agent. Curing of a conductive addition reaction-curable silicone elastomer composition containing conductive particles whose surfaces are coated with a fatty acid and which has been surface-treated with an epoxy group-containing organoalkoxysilane, and further containing the conductive particles treated with an organosilazane. A semiconductor device, wherein a semiconductor element is covered with an object. The semiconductor device according to claim 10, wherein the semiconductor element is bonded to a heat sink through a cured product of the conductive addition reaction-curable silicone elastomer composition according to claim 10.

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