KR20100113985A - Thermal conductive adhesive - Google Patents

Abstract

PURPOSE: A thermo-conductive adhesive is provided to secure the proper adhesion force to an object including a heating member and a thermal insulation member. CONSTITUTION: A thermo-conductive adhesive contains the following: 100 parts of polyimide silicone resin by weight with the weight average molecular weight of 5,000~150,000; 100~10,000 parts of thermally conductive filler by weight with the electric insulation property; and the balance of organic solvent.

Description

Thermally Conductive Adhesive {THERMAL CONDUCTIVE ADHESIVE}

TECHNICAL FIELD The present invention relates to a thermally conductive adhesive, and more particularly, to a thermally conductive adhesive suitable for bonding an electronic element and a heat radiating member or a heat generating member.

In recent years, the heat generation of an electronic element and the member which mounts the said electronic element is increasing with high performance, miniaturization, and high density of an electronic element, for example, a central processing unit (CPU) of a computer, and a chip set. Therefore, cooling of an electronic element becomes a very important technique in maintaining the performance of an electronic element and the member which mounted the said electronic element. The heat dissipation efficiency of an electronic device is generally raised by bringing an electronic device into contact with a material having good thermal conductivity. Therefore, the demand of the heat radiation material (TIM) which has the outstanding thermal conductivity is increasing.

The heat dissipation material is placed between the electronic element and the cooling system (for example, a heat sink), for example, and plays a role of effectively transferring heat generated from the electronic element to the cooling system. The heat dissipation material is classified into a sheet-like molding and a paste-like composition from its shape or use method. Sheet-like molded articles are classified into, for example, an elastomer (elastic polymer material) type heat dissipation sheet and a thermosoftening type phase change sheet (sheet using a heat dissipating material that changes in phase with temperature). Paste-like compositions are, for example, non-curable heat dissipation greases, and pastes at the time of application, and are classified into heat dissipation gels or heat dissipating adhesives which are gelated or elastomerized by heat treatment, for example.

These heat dissipating materials are generally composite materials in which a thermally conductive material is densely packed in an organic polymer material. The thermal conductivity of the organic polymer material is generally small, and there is no great difference depending on the type of the organic polymer material. Therefore, the thermal conductivity of the heat dissipating material largely depends on the volume filling rate of the thermal conductive material in the organic polymer material. Therefore, it was important how much of the thermally conductive material to fill in the organic polymer material.

Heat dissipating adhesives are required to have high thermal conductivity and at the same time have adhesion under various environments or stresses. The higher density of the thermally conductive material in the organic polymer material, the better the heat dissipation of the heat dissipating material. However, the higher the density of the thermally conductive material contained in the organic polymer material, the weaker the heat dissipating material itself becomes, and the adhesion to the flexible or adherend worsens.

Epoxy resins, silicone polymers, polyimides and the like are known as organic polymer materials for heat dissipating adhesives. However, although epoxy resins have good adhesiveness, they are disadvantageous in heat resistance and durability. Therefore, silicone polymers are preferably used in view of wettability to thermally conductive materials, flexibility after curing, thermal stability, or the like (see, for example, Patent Documents 1 and 2 below). However, in some cases, the adhesive and the heat dissipation are not satisfied as the heat dissipating material using the silicone polymer.

In addition, when the polyimide which improved heat resistance was used, since a polyimide resin is solid, a heat conductive material cannot be filled, but it had to melt | dissolve and fill it with a solvent etc. In order to avoid it, it is necessary to fill the heat conductive material in the polyamic acid solution which becomes a precursor, and since heat hardening normally requires 300 degreeC or more, the thermal load to the surrounding cannot be avoided.

Moreover, it is known to use polyimide silicone resin for surface protection of wiring parts, such as a semiconductor element and a printed board, and it is high adhesiveness and durability with respect to a base material under high humidity conditions compared with silicone rubber (for example, following patent document 3 See). It is also disclosed to use the composition containing this polyimide silicone resin as an adhesive agent of a semiconductor (for example, refer patent document 4). However, no studies have been conducted on thermally conductive adhesives using these polyimide silicone resins, particularly thermally conductive adhesives requiring electrical insulation.

Japanese Patent Laid-Open No. 2006-342200 Japanese Patent Publication No. 61-3670 Japanese Patent Laid-Open No. 2002-012667 Japanese Patent Laid-Open No. 2006-005159

An object of the present invention is to provide an electrically insulating thermally conductive adhesive (also referred to as heat dissipating paste) having excellent thermal conductivity and excellent adhesiveness to an adherend, for example, a heat generating member and a heat dissipating member.

The present invention is the following thermal conductive adhesive.

(A) 100 mass parts of polyimide silicone resin of the weight average molecular weights 5,000-150,000 which have a repeating unit represented by following General formula (1),

(B) 100 to 10,000 parts by mass of electrically insulating thermally conductive filler, and

(C) organic solvent

Thermally conductive adhesive containing a.

(Wherein, W is a tetravalent organic group, X is a divalent organic group, Y is a divalent silicon residue represented by the following formula (2), 0.05≤m≤0.8, 0.2≤n≤0.95, m + n = 1)

In formula (2), R ¹ is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, R ² is a radical polymerizable group, a and b are each an integer of 1 to 20, a + b Is 2 to 21)

In one embodiment of the present invention, the thermally conductive adhesive further includes 0.1 to 10 parts by mass of (D) peroxycarbonate. Peroxycarbonate functions as a hardening | curing agent which accelerates the polymerization hardening of a radically polymerizable group.

In one embodiment of the present invention, R ² is a vinyl group, a propenyl group, a (meth) acryloyloxypropyl group, a (meth) acryloyloxyethyl group, a (meth) acryloyloxymethyl group or a styryl group, more preferably It is vinyl.

In one embodiment of the present invention, the thermally conductive adhesive has an adhesive strength to the copper plate of 3 Mpa or more, preferably 5 to 10 Mpa.

When the heat conductive adhesive agent of this invention is put on a copper plate and heated, the said heat conductive adhesive will flow and will wet and spread on the surface of a copper plate. Therefore, by heat treatment, it adheres to the copper plate and brings good adhesion.

When the thermally conductive adhesive of the present invention is wetted with the adherend and heated to cure, the adhesive flows to wet the surface of the adherend and spreads, and the solvent volatilizes, so that the thermally conductive filler is applied to the surface of the cured adhesive. Exposed. Thus, good thermal conductivity is obtained.

The present invention also provides an electronic device bonded to the heat dissipation member or the heat generating member by a material obtained by curing the above-described thermal conductive adhesive.

The thermally conductive adhesive of the present invention has excellent thermal conductivity by including a polyimide silicone resin, a thermally conductive filler, and an organic solvent of a specific structure, and also has excellent adhesiveness to the adherend.

Hereinafter, the heat conductive adhesive agent of this invention is further demonstrated in detail.

(A) polyimide silicone resin

The polyimide silicone resin has a repeating unit represented by the following formula (1).

<Formula 1>

W in Formula 1 is a tetravalent organic group. W is, for example, pyromellitic dianhydride, 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 3, 3 ', 4,4'-diphenylethertetracarboxylic dianhydride, 3,3', 4,4'-diphenylsulfontetracarboxylic dianhydride, 3,3 ', 4,4'-benzophenonetetracarb Acid dianhydride, ethylene glycol bistrimellitic dianhydride, 4,4'-hexafluoropropylidenebisphthalic dianhydride, 2,2-bis [4- (3,4-phenoxydicarboxylic acid) phenyl] propane And may be selected from residues of acid dianhydrides.

X in Formula 1 is a divalent organic group. X is group derived from the diamine used for the conventional polyimide resin, for example. The diamine is one or a combination of two or more selected from, for example, aliphatic diamines and aromatic diamines. Aliphatic diamines are, for example, tetramethylenediamine, 1,4-diaminocyclohexane, 4,4'-diaminodicyclohexylmethane. Aromatic diamine is phenylenediamine, 4,4'- diamino diphenyl ether, 2, 2-bis (4-aminophenyl) propane, for example. X is preferably a group derived from an aromatic diamine represented by the following formula (3).

B in Formula (3) is a group represented by any one of the following Formulas (4), (5) and (6).

Y in General formula (1) is a bivalent silicone residue represented by following General formula (2).

<Formula 2>

R ¹ in the formula (2) is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms. R ¹ is, for example, a methyl group or an ethyl group.

R ² in the formula (2) is a radical polymerizable group. R ² is, for example, a vinyl group, a propenyl group, a (meth) acryloyloxypropyl group, a (meth) acryloyloxyethyl group, a (meth) acryloyloxymethyl group, or a styryl group. Preferably, R ² is a vinyl group in view of easy availability of raw materials. As long as the said radically polymerizable group is a silicone part of polyimide silicone resin, you may exist in any site | part of an edge part and a center part, for example.

A and b in the formula (2) are each an integer of 1 to 20, preferably 3 to 20. The sum of a + b is 2 or more and 21 or less. Here, when each of a and b is larger than 20, or a + b is larger than 21, the adhesive force to the adherend becomes weak.

M and n in the general formula (1) express an effect derived from the repeating unit, and therefore 0.05 ≦ m ≦ 0.8, 0.2 ≦ n ≦ 0.95, preferably 0.05 ≦ m ≦ 0.5, 0.5 <n ≦ 0.95. If it exists in this range, favorable adhesiveness with respect to a to-be-adhered body will be obtained.

The sum total of m + n in General formula (1) is 1.

The weight average molecular weight of the polyimide silicone resin is 5,000 to 150,000, preferably 20,000 to 150,000. This is because when the molecular weight is lower than the lower limit, toughness as a resin is not expressed. On the other hand, when the molecular weight is higher than the upper limit, the mixing with the thermally conductive filler described later becomes difficult.

The said polyimide silicone resin can be manufactured by the well-known method mentioned below, for example.

Initially, tetracarboxylic dianhydride for inducing W, diamine for inducing X and diaminopolysiloxane for inducing Y are introduced into a solvent and reacted at low temperature, for example, 0 to 50 ° C. The solvent is a combination of one or two or more selected from, for example, N-methyl-2-pyrrolidone (NMP), cyclohexanone, γ-butyrolactone and N, N-dimethylacetamide (DMAc). Moreover, in order to make it easy to remove the water produced | generated at the time of imidation by azeotropy, aromatic hydrocarbons, for example, toluene and xylene, can be used together. By the said reaction, the polyamic acid which is a precursor of a polyimide resin is manufactured. Next, the solution of the polyamic acid is preferably heated to a temperature of 80 to 200 ° C, particularly preferably 140 to 180 ° C. By the said temperature rising, the acid amide of a polyamic acid dehydrates and ring-closes, and the solution of polyimide silicone resin is obtained. The solution is introduced into a solvent such as water, methanol, ethanol or acetonitrile to form a precipitate. The produced precipitate is dried to obtain a polyimide silicone resin.

The molar ratio of the sum of the diamine and the diaminopolysiloxane to the tetracarboxylic dianhydride is preferably in the range of 0.95 to 1.05, particularly preferably 0.98 to 1.02.

In order to adjust the molecular weight of the polyimide silicone resin, difunctional carboxylic acids such as phthalic anhydride and monofunctional amines such as aniline may be added into the solution. The addition amount of these compounds is 2 mol% or less with respect to tetracarboxylic acid and diamine, respectively.

In the imidation process, a dehydrating agent and an imidation catalyst can be added, and it can also be imidated by heating around 50 degreeC as needed. Dehydrating agents are acid anhydrides, for example, acetic anhydride, propionic anhydride and trifluoroacetic anhydride. The use amount of dehydrating agent is 1-10 mol with respect to 1 mol of diamines, for example. Imidation catalysts are, for example, tertiary amines, for example pyridine, collidine, lutidine and triethylamine. The usage-amount of an imidation catalyst is 0.5-10 mol with respect to 1 mol of dehydrating agents used, for example.

When a plurality of diamines and / or a plurality of tetracarboxylic dianhydrides are used, for example, a method of co-condensation after mixing all the raw materials in advance, and sequentially adding two or more diamines or tetracarboxylic dianhydrides while reacting them individually. can do. However, the reaction method is not particularly limited to this example.

(B) electrically insulating thermally conductive filler

Electrically insulating thermally conductive fillers are metal oxide and ceramic powder, for example. The said metal powder is zinc oxide powder and alumina powder, for example. The ceramic powder is, for example, silicon carbide powder, silicon nitride powder, boron nitride powder, or aluminum nitride powder. The thermally conductive filler may be appropriately selected in terms of stability or cost.

The shape of the thermally conductive filler is not particularly limited and is, for example, granular, branched, flaked, and indefinite. One kind or a mixture of two or more kinds of thermally conductive filler powders having these shapes may be used. Although the particle size distribution of a thermally conductive filler is not specifically limited, For example, 90 weight% or more, Preferably it is 95 weight% or more in the range of 0.05-100 micrometers. Although the average particle diameter of a thermally conductive filler is not specifically limited, For example, it is the range of 1-50 micrometers. As the thermally conductive filler, for example, one of a single distribution (seal) can be used. However, in order to uniformly and uniformly disperse the thermally conductive filler in the adhesive, it is more effective to combine the plurality of thermally conductive fillers having different shapes and particle diameters into a multimodal distribution than to use a single distribution of thermally conductive fillers.

The ratio of the compounding quantity of the said heat conductive filler in the heat conductive adhesive agent of this invention is 100-10,000 mass parts, Preferably it is 200-6,000 mass parts per 100 mass parts of polyimide silicone resin. When the ratio of the compounding quantity of the said heat conductive filler is less than the said minimum, sufficient thermal conductivity will not be obtained when the heat conductive adhesive agent of this invention is used. Moreover, when the ratio of the compounding quantity of the said heat conductive filler exceeds the said upper limit, when the heat conductive adhesive agent of this invention is used, sufficient adhesive strength with a to-be-adhered body will not be obtained.

(C) organic solvent

It is preferable that the organic solvent is compatible with the component (A) and does not affect the surface state of the component (B). The organic solvent is a combination of one or two or more selected from, for example, ethers, ketones, esters, cellosolves, amides and aromatic hydrocarbons. Ethers include, for example, tetrahydrofuran and anisole. Ketones include cyclohexanone, 2-butanone, methyl isobutyl ketone, 2-heptanone, 2-octanone and acetophenone, for example. Esters include butyl acetate, methyl benzoate and γ-butyrolactone, for example. Cellosolves include, for example, butylcarbitol acetate, butyl cellosolve acetate, and propylene glycol monomethyl ether acetate. Amides include, for example, N, N-dimethylformamide, N, N-dimethylacetamide and N-methyl-2-pyrrolidone. Aromatic hydrocarbons such as toluene and xylene. The organic solvent is preferably selected from ketones, esters, cellosolves and amides. The organic solvent is particularly preferably butylcarbitol acetate, γ-butyrolactone, propylene glycol monomethyl ether acetate and N-methyl-2-pyrrolidone. These solvents can also be used individually or in combination of 2 or more types.

The amount of the organic solvent is, for example, in consideration of the solubility of the polyimide silicone resin, the workability at the time of application of the thermally conductive adhesive, or the thickness of the coating, and the amount of the polyimide silicone resin is usually 10 to 10 to the total of the resin and the solvent. It is used within the range which becomes 60 mass%, Preferably it is 20-50 mass%. The composition may be prepared at a relatively high concentration at the time of preservation of the composition and diluted to the desired concentration at the time of use.

The thermally conductive adhesive of the present invention may further contain (D) peroxycarbonate as an optional component. In the presence of peroxycarbonate, even at a relatively low temperature, the radical polymerizable group bonded to the silicon atom in the polyimide silicone resin rapidly cures, and the performance such as solvent resistance is improved. Peroxy carbonate is monoperoxy carbonate, such as t-butyl peroxy isopropyl carbonate, t-butyl peroxy 2-ethylhexyl carbonate, t-amyl peroxy 2-ethylhexyl carbonate, for example; Di (2-ethylhexyl) peroxydicarbonate, 1,6-bis (t-butylperoxycarbonyloxy) hexane, bis (4-t-butylcyclohexyl) peroxydicarbonate, di (2-ethoxyethyl) Peroxy dicarbonate, di (n-propyl) peroxydicarbonate, diisopropyl peroxydicarbonate, etc. are mentioned. The peroxy carbonate is preferably t-butylperoxy 2-ethylhexyl carbonate, t-amyl peroxy 2-ethylhexyl carbonate, 1, in terms of curability, compatibility with polyimide silicone resins, and storage stability of an adhesive. 6-bis (t-butylperoxycarbonyloxy) hexane and bis (4-t-butylcyclohexyl) peroxydicarbonate.

The amount of peroxycarbonate is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the polyimide silicone resin. When the compounding quantity exceeds the said upper limit, there exists a tendency for the storage stability of the heat conductive adhesive agent of this invention, and the high temperature and high humidity resistance of hardened | cured material to fall.

The polyimide silicone resin exhibits excellent heat resistance, mechanical strength, solvent resistance, and adhesion to various substrates by thermal curing.

Although the hardening conditions of the adhesive agent of this invention are not specifically limited, It is the range of 80 degreeC or more and 300 degrees C or less, Preferably it is 100 degreeC or more and 200 degrees C or less. When hardening below the said lower limit, heat hardening takes too time and is not practical. When components and compositions are selected to cure at a low temperature below the lower limit, there is a possibility that a problem arises in the storage stability of the adhesive. In addition, unlike the conventional polyamic acid solution, the thermally conductive adhesive of the present invention can suppress thermal deterioration of the substrate because it does not require long-term heating at a high temperature of 300 ° C or more for curing.

In addition to the components described above, the thermally conductive adhesive of the present invention may be, for example, an anti-aging agent, an ultraviolet absorber, an adhesive improver, a flame retardant, a surfactant, a storage stability improver, an ozone deterioration inhibitor, an optical stabilizer, a thickener, a plasticizer, a silane coupling agent, and an oxidation agent. One or two or more selected from an inhibitor, a heat stabilizer, a radiation blocker, a nucleating agent, a lubricant, a pigment and a physical property modifier may be added within a range that does not impair the object of the present invention and the effect of the thermally conductive adhesive.

The thermally conductive adhesive of the present invention has a viscosity at 25 ° C., preferably 0.5 to 2000 Pa · s, preferably 1.0 to 1000 Pa · s.

The thermal conductivity (W / mK) of the thermally conductive adhesive of the present invention is preferably 0.5 or more, more preferably 1.0 or more, particularly preferably 3 or more.

The adhesive strength (MPa) to the copper plate of the heat conductive adhesive agent of this invention becomes like this. Preferably it is three or more, More preferably, it is five or more, Especially preferably, it is six or more. Preferably the adhesive strength (MPa) after leaving 240 degreeC in the high temperature, high-humidity atmosphere of 80 degreeC and 95 RH is preferably the same as the above.

The thermally conductive adhesive of the present invention is preferably used for, for example, an adhesive of an LED chip having a large heat generation amount for high brightness, or an adhesive of a semiconductor element having a large heat generation amount per unit area associated with miniaturization and weight reduction.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.

1. Synthesis of Polyimide Silicone Resin

Four types of polyimide silicone resins were prepared as shown in Synthesis Examples 1 to 4 below.

Synthesis Example 1

Into a flask equipped with a stirrer, a thermometer, and a nitrogen replacement device, 88.8 g (0.2 mol) of 4,4'-hexafluoropropylidenebisphthalic anhydride and 500 g of n-methyl-2-pyrrolidone were charged. Next, 142.2 g (0.16 mol) of diaminosiloxane and 16.4 g (0.04 mol) of 2,2-bis [4- (4-aminophenoxy) phenyl] propane represented by the formula (7) were n-methyl-2-pi A solution dissolved in 100 g of ralidone was prepared. The solution was added dropwise into the flask. During the dropping, the temperature of the reaction system was adjusted not to exceed 50 ° C. After completion of the dropwise addition, the mixture was further stirred at room temperature for 10 hours. Next, after attaching a reflux condenser with a water container to the flask, 50 g of xylene was added, the temperature was raised to 150 ° C, and the temperature was maintained for 6 hours. As a result, a yellowish brown solution was obtained.

The yellowish brown solution obtained above was cooled to room temperature (25 ° C), poured into methanol and reprecipitated. 190 g of the obtained precipitate was dried, and its linear absorption spectrum was measured. As a result, absorption (1,640 cm ^-1 ) based on unreacted polyamic acid did not appear, and absorption based on imide groups was confirmed at 1,780 cm ^-1 and 1,720 cm ^-1 . Next, it was 33,000 when the weight average molecular weight (polystyrene conversion) was measured by the gel permeation chromatography (GPC) which uses tetrahydrofuran as a solvent. The product is called polyimide silicone resin (I).

Synthesis Example 2

Into a flask equipped with a stirrer, a thermometer, and a nitrogen replacement device, 88.8 g (0.2 mol) of 4,4'-hexafluoropropylidenebisphthalic anhydride and 500 g of n-methyl-2-pyrrolidone were charged. Next, 165.3 g (0.1 mol) of diaminosiloxane represented by the formula (8) and 41.1 g (0.1 mol) of 2,2-bis [4- (4-aminophenoxy) phenyl] propane were n-methyl-2-pi A solution dissolved in 100 g of ralidone was prepared. The solution was added dropwise into the flask. During the dropping, the temperature of the reaction system was adjusted not to exceed 50 ° C. After completion of the dropwise addition, the mixture was further stirred at room temperature for 10 hours. Next, after attaching a reflux condenser with a water container to the flask, 50 g of xylene was added, the temperature was raised to 150 ° C, and the temperature was maintained for 6 hours. As a result, a yellowish brown solution was obtained.

The yellowish brown solution obtained above was cooled to room temperature (25 ° C), poured into methanol and reprecipitated. 240 g of the obtained precipitates were dried, and the linear absorption spectrum thereof was measured. As a result, absorption (1,640 cm ^-1 ) based on unreacted polyamic acid did not appear, and absorption based on imide groups was confirmed at 1,780 cm ^-1 and 1,720 cm ^-1 . Next, it was 33,000 when the weight average molecular weight (polystyrene conversion) was measured by the gel permeation chromatography (GPC) which uses tetrahydrofuran as a solvent. The product is called polyimide silicone resin (II).

Synthesis Example 3 (Comparative)

Into a flask equipped with a stirrer, a thermometer, and a nitrogen replacement device, 88.8 g (0.2 mol) of 4,4'-hexafluoropropylidenebisphthalic anhydride and 500 g of n-methyl-2-pyrrolidone were charged. Next, 263.1 g (0.08 mol) of diaminosiloxane and 49.3 g (0.12 mol) of 2,2-bis [4- (4-aminophenoxy) phenyl] propane represented by the formula (9) were n-methyl-2-pi. A solution dissolved in 100 g of ralidone was prepared. The solution was added dropwise into the flask. During the dropping, the temperature of the reaction system was adjusted not to exceed 50 ° C. After completion of the dropwise addition, the mixture was further stirred at room temperature for 10 hours. Next, after attaching a reflux condenser with a water container to the flask, 50 g of xylene was added, the temperature was raised to 150 ° C, and the temperature was maintained for 6 hours. As a result, a yellowish brown solution was obtained.

The yellowish brown solution obtained above was cooled to room temperature (25 ° C), poured into methanol and reprecipitated. 330 g of the obtained precipitate was dried, and its linear absorption spectrum was measured. As a result, absorption (1,640 cm ^-1 ) based on unreacted polyamic acid did not appear, and absorption based on imide groups was confirmed at 1,780 cm ^-1 and 1,720 cm ^-1 . Next, it was 35,000 when the weight average molecular weight (polystyrene conversion) was measured by the gel permeation chromatography (GPC) which uses tetrahydrofuran as a solvent. The product is called polyimide silicone resin (III).

Synthesis Example 4 (Comparative)

Into a flask equipped with a stirrer, a thermometer, and a nitrogen replacement device, 88.8 g (0.2 mol) of 4,4'-hexafluoropropylidenebisphthalic anhydride and 500 g of n-methyl-2-pyrrolidone were charged. Next, 244.8 g (0.08 mol) of diaminosiloxane and 49.3 g (0.12 mol) of 2,2-bis [4- (4-aminophenoxy) phenyl] propane represented by the formula (10) were n-methyl-2-pi. A solution dissolved in 100 g of ralidone was prepared. The solution was added dropwise into the flask. During the dropping, the temperature of the reaction system was adjusted not to exceed 50 ° C. After completion of the dropwise addition, the mixture was further stirred at room temperature for 10 hours. Next, after attaching a reflux condenser with a water container to the flask, 50 g of xylene was added, the temperature was raised to 150 ° C, and the temperature was maintained for 6 hours. As a result, a yellowish brown solution was obtained.

The yellowish brown solution obtained above was cooled to room temperature (25 ° C), poured into methanol and reprecipitated. 340 g of the obtained precipitate was dried, and its linear absorption spectrum was measured. As a result, absorption (1,640 cm ^-1 ) based on unreacted polyamic acid did not appear, and absorption based on imide groups was confirmed at 1,780 cm ^-1 and 1,720 cm ^-1 . Next, it was 35,000 when the weight average molecular weight (polystyrene conversion) was measured by the gel permeation chromatography (GPC) which uses tetrahydrofuran as a solvent. The product is called polyimide silicone resin (IV).

2. Preparation of Adhesive

The following raw materials were used.

(A) Polyimide Silicone Resin: The polyimide silicone resins (I), (II), (III) or (IV) obtained in Synthesis Examples 1 to 4 were used.

(B) electrically insulating thermally conductive filler:

(B1) Thermally conductive filler A: Alumina having an average particle diameter of 10 µm (specific gravity 3.98)

(B2) Thermally conductive filler B: Alumina having an average particle diameter of 1 μm (specific gravity 3.98)

(C) organic solvent: butylcarbitol acetate (BCA)

(D) peroxycarbonate: t-butylperoxy-2-ethylhexyl carbonate

[Examples 1 to 4 and Comparative Examples 1 to 2]

The masses of (A) polyimide silicone resins (I) to (IV), respectively, (B) electrically insulating thermally conductive fillers (B1 and B2), (C) organic solvents, and (D) peroxycarbonates in Table 1 It injected | thrown-in to the autorotation mixer at a ratio, it stirred so that it might become uniform, and defoamed, and obtained the adhesive agent.

3. Evaluation test

About the adhesive agent obtained in Examples 1-4 and Comparative Examples 1-2, the evaluation test of the viscosity, thermal conductivity, and adhesive strength was done according to the following method. In addition, the evaluation test was done with the procedure similar to the above about the silicone rubber C (commercial product) and D (commercial product) of a heat-curable one-liquid type (Comparative Example 3 and Comparative Example 4, respectively). The results are shown in Table 2.

(1) viscosity

The viscosity of each adhesive agent is measured at 25 degreeC using a BH type rotational viscometer.

(2) thermal conductivity

Each adhesive agent flows into the groove of a Teflon (trademark) plate, dried at 80 ° C for 30 minutes, and then the adhesive is heated at 150 ° C for 1 hour to prepare a test piece of 10 mmφ × 1 mm. . Using a laser flash method thermal constant measuring device (LFA447 (manufactured by NETZSCH)), the thermal diffusivity and specific heat capacity of the test piece were measured to obtain thermal conductivity.

(3) adhesive strength

Each adhesive is applied to a copper plate (100 mm x 25 mm x 1 mm) with a coating area of 20 mm x 20 mm and joined with another copper plate of the same size. The bonded copper plate is dried at 80 ° C for 30 minutes, then further dried at 150 ° C for 2 minutes under a pressure of 4 MPa, and heated at 150 ° C for 1 hour to obtain a test piece. The shear bond strength of the test piece is measured at a speed of 5 mm / min using an autograph (STROGRAPH V10-D (manufactured by Toyo Seiki Co., Ltd.)).

The test piece obtained in the same manner as above was exposed to 80 ° C / 95% RH for 240 hours (high temperature and high humidity test), and shear bond strength (after high temperature and high humidity test) was measured in the same manner as described above.

From the above results, the adhesives I to IV had an appropriate viscosity, good thermal conductivity of 1.1 to 3.1 W / mK, good adhesive strength of 6 to 11 MPa, and almost no decrease in adhesive strength before and after the high temperature and high humidity test. Did.

Claims (5)

(A) 100 mass parts of polyimide silicone resin of the weight average molecular weights 5,000-150,000 which have a repeating unit represented by following General formula (1),
(B) 100 to 10,000 parts by mass of electrically insulating thermally conductive filler, and
(C) organic solvent
Thermally conductive adhesive containing a.
<Formula 1>

(Wherein, W is a tetravalent organic group, X is a divalent organic group, Y is a divalent silicon residue represented by the following formula (2), 0.05≤m≤0.8, 0.2≤n≤0.95, m + n = 1)
<Formula 2>

In formula (2), R ¹ is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, R ² is a radical polymerizable group, a and b are each an integer of 1 to 20, a + b Is 2 to 21) The compound according to claim 1, wherein R ² is selected from the group consisting of vinyl group, propenyl group, (meth) acryloyloxypropyl group, (meth) acryloyloxyethyl group, (meth) acryloyloxymethyl group and styryl group Thermally conductive adhesive. The heat conductive adhesive of Claim 1 or 2 which further contains 0.1-10 mass parts of (D) peroxycarbonates. The heat conductive adhesive of Claim 1 or 2 whose adhesive strength with respect to a copper piece is 3 Mpa or more. An electronic member comprising an electronic element bonded to a heat radiating member or a heat generating member by a material obtained by curing the thermal conductive adhesive according to claim 1.