JPH11349905A - Pressure-sensitive adhesive sheets having thermal conductivity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject sheet having excellent adhesion between a substrate and a pressure-sensitive adhesive agent composition layer and retention performances in use at a high temperature without providing an undercoating layer by using a plastic film containing a granular solid exposed to the surface as the substrate and forming a pressure-sensitive adhesive composition layer on the substrate. SOLUTION: This pressure-sensitive adhesive sheet having thermal conductivity is obtained by using a plastic film containing 2-50 vol.% of a granular body in which the granular body is exposed to the surface of the film as a substrate and forming a pressure-sensitive adhesive agent composition layer on the substrate. A polyimide (amide) is preferable as the material of the substrate. Aluminum oxide or boron nitride having 2-10 μm particle diameter is preferable as the granular body. In order to expose the granular body to the surface of the substrate, the following method is adopted. Namely the granular body is added to a polymer to give a composition, which is formed into a film. The surface of the film is subjected to sputtering etching treatment. A composition comprising a (meth)acrylic acid alkyl ester-based polymer as a main agent is preferable as the pressure-sensitive adhesive agent composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to fixing electronic parts,
In particular, fixing of electronic parts and heat radiation members, and other building materials,
The present invention relates to heat conductive pressure-sensitive adhesive sheets used for fixing members in various fields such as vehicles, aircraft, and ships.

[0002]

2. Description of the Related Art Conventionally, in a hybrid package, a multi-module, or an electronic component such as a plastic or metal hermetically sealed integrated circuit, the amount of heat generated has increased due to the high integration of an IC circuit. In view of the possibility that the electronic components may malfunction due to a rise in temperature, measures have been taken to prevent the above-mentioned malfunctions by attaching a heat radiating member such as a heat sink to the electronic components.

As a method of attaching a heat radiation member to an electronic component, there is known a method of using an adhesive obtained by adding aluminum powder or the like to a composition containing a polymerizable acrylate monomer and a free radical initiator (US). Patent 4,72
2,960). However, in this method, after applying the adhesive to one or both of the electronic component and the heat radiating member, it is necessary to use a primer or block oxygen to perform a curing treatment. There has been a problem that the manufacturing efficiency of the electronic device is poor, such as requiring labor and temporarily fixing the adherend until it is cured.

[0004] A method using an adhesive sheet containing silver particles having a particle diameter larger than the thickness of the adhesive layer has also been proposed (US Pat. No. 4,606,962).
However, when silver particles are included, the viscosity is extremely increased during the preparation of the adhesive composition and lacks fluidity, and handling properties, especially coating workability, are deteriorated. There was a problem that it could not be made into a sheet if it did not come out or was severe.

Further, an acrylic polymer having a polar group
A method using a heat-conductive pressure-sensitive adhesive tape obtained by randomly dispersing heat-conductive electric insulating particles into a resin has also been proposed (Japanese Patent Laid-Open No. Hei 6-88061: European Patent EP-566).
093-Al). However, since this adhesive tape does not have a support, when the terminal part of the electronic component bites into the pressure-sensitive adhesive layer, it has an electrical insulating property (volume resistance value, breakdown voltage).
Can be remarkably impaired, and cannot be used in parts where reliability as an electrical insulating material is strongly required.

Further, Japanese Patent Application Laid-Open No. Hei 5-198709 (US Pat. No. 5,213,868) discloses that a heat conductive interface material disposed between a heat source and a heat dissipator is made of nylon or polyester. An acrylic pressure-sensitive adhesive layer containing thermally conductive electrical insulating particles is provided on a support made of an electrically insulating plastic film such as polyimide, and the air between the heat source and the heat dissipator is removed. One in which a through hole, emboss, groove or the like is formed has been proposed. However, this material has poor adhesion between the support and the pressure-sensitive adhesive layer, and has a problem that it is easily anchored and broken at both interfaces under high temperature use.

[0007] In order to improve the adhesion between the support and the pressure-sensitive adhesive layer, it is common practice to provide one or more layers called an undercoat between the support and the pressure-sensitive adhesive layer. This is formed by dissolving a material having an intermediate polarity between the support and the pressure-sensitive adhesive layer in an organic solvent or the like, applying the solution on the support, and drying. However, in this case, problems such as complicated manufacturing operations and environmental deterioration due to the use of an organic solvent or the like occur.

[0008]

As described above, according to the known heat-conductive pressure-sensitive adhesive tape or the like, the fixing of the electronic component and the heat radiating member can be easily performed without much labor and time. Although there is an advantage that the bonding treatment can be performed, if there is no support, there is a problem in terms of insulation reliability, while if there is a support, there is a problem in adhesion between the support and the pressure-sensitive adhesive layer. In order to solve this problem with an undercoat layer, there have been problems such as complicated manufacturing operations and environmental deterioration.

In view of such circumstances, the present invention provides a method for fixing electronic components, in particular, fixing electronic components to heat radiating members, and fixing members in various fields such as building materials, vehicles, aircraft, and ships. As a heat conductive pressure-sensitive adhesive sheet for use, it is composed of a support and a pressure-sensitive adhesive layer, has no problems in terms of insulation reliability, and is complicated in manufacturing operations and deteriorating the environment. Heat-conductive pressure-sensitive adhesive sheets with improved adhesion between the support and the pressure-sensitive adhesive layer without forming an undercoat layer that causes the above problems, and excellent in holding performance at high temperature use It is intended to provide.

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, as a support, a plastic film containing a specific amount of powdered solids, When a layer of the pressure-sensitive adhesive composition is used and a layer of the pressure-sensitive adhesive composition is provided thereon, even if the undercoat layer is not provided, the support and the layer of the pressure-sensitive adhesive composition can be used. It has been found that heat-conductive pressure-sensitive adhesive sheets having excellent adhesiveness to the adhesive and excellent holding performance under high-temperature use can be obtained, thereby completing the present invention.

That is, the present invention provides a method for preparing a powdery solid from 2 to 5
A plastic film containing 0% by volume as a support,
The present invention relates to heat-conductive and pressure-sensitive adhesive sheets (Claim 1) in which the powdery solid is exposed on the surface of the support and a layer of the pressure-sensitive adhesive composition is provided thereon. . In particular,
According to the present invention, as such heat conductive pressure-sensitive adhesive sheets, the plastic film constituting the support is made of polyimide (amide) (claim 2), and the powdery solid is aluminum oxide or aluminum oxide. The pressure-sensitive adhesive composition comprising boron nitride (claim 3), the pressure-sensitive adhesive composition comprising an alkyl (meth) acrylate-based polymer as the main component (claim 4), and the pressure-sensitive adhesive composition comprising: One containing a thermally conductive filler (Claim 5), one in which the pressure-sensitive adhesive composition contains a silane coupling agent (Claim 6)
Can be provided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the thickness of a support containing 2 to 50% by volume of a granular solid is usually 1%.
A plastic film of 2 μm to 4 mm is used. The polymer materials of the plastic film include polyimide (amide), polyethylene terephthalate, polyethylene naphthalate, polytetrafluoroethylene, polyetherketone, polyethersulfone, polymethylpentene, polyetherimide, polysulfone, and polyolefin. Examples include enylene sulfide, polyesterimide, and aromatic polyamide. Among these, polyimide (amide), that is, polyimide or polyimide amide is preferable in terms of thermal dimensional stability and long-term heat resistance reliability, and polytetrafluoroethylene is also preferably used.

The powdery solids include aluminum oxide (Al ₂ O ₃ ), boron nitride (BN), SiO ₂ , Ti
B ₂ , Si ₃ N ₄ , TiO ₂ , MgO, NiO, Fe ₂
O ₃ , CuO and the like. Among these, aluminum oxide or boron nitride is preferable in terms of thermal conductivity and availability. The particle size is usually 0.5 to 250 µm, preferably 1 to 100 µm, more preferably 2 to 10 µm. The shape may be any shape such as a sphere, a needle, a flake, or a star. The content is 2 to 2 in the film.
It is 50% by volume, preferably 10 to 35% by volume. If the amount is less than 2% by volume, good results are hardly obtained in terms of thermal conductivity and adhesion to the layer of the pressure-sensitive adhesive composition. If it exceeds 50% by volume, problems tend to occur in terms of film strength and the like.

In the present invention, a plastic film containing such a particulate solid is used as a support. However, it is necessary that the above-mentioned particulate solid is exposed on the surface of the support, that is, on the film surface. Importantly, by providing a layer of the pressure-sensitive adhesive composition on the exposed surface, a remarkable effect can be obtained in improving the adhesion between the layer and the support. That is, even if the plastic film contains a particulate solid, if the particulate solid is not exposed on the film surface, the adhesion between the layer and the support is poor.

In order to expose the particulate solid on the surface of the support, for example, a polymer such as polytetrafluoroethylene is mixed with the particulate solid and sintered, and this is cut with a cutting tool or the like to form a film. A cutting method may be employed. Further, as another effective method, a composition containing a polymer and a powdery solid is formed into a film by a casting method or an extrusion method. Etching by a treatment or the like may expose the powdery solid on the film surface.

When the etching process is performed by high-frequency sputtering, the atmospheric pressure during the process is 0.0005 to 0.5.
The operation may be performed under the conditions of 5 Torr, a frequency of several hundred KHz to several tens of MHz, a practically assigned industrial frequency of 13.56 MHz, and a discharge power of 0.1 to 5.0 W / cm ² . Since the processing time needs to be longer as the discharge power is smaller, it is practically preferable to increase the discharge power and reduce the processing time. The processing degree is approximately expressed as a product of the discharge power and the processing time. As the atmosphere gas, all gases can be used, but it is better to avoid extremely active gases such as chlorine gas and fluorine gas, and organic gases which undergo discharge polymerization during sputter etching. In practice, inert gases such as argon,
Air, nitrogen, steam, carbon dioxide and the like are used.

In a plastic film obtained by such a cutting method or an etching treatment, whether or not a powdery solid is exposed on the surface can be easily confirmed by observing the surface by ESCA (photoelectron spectroscopy). For example, when the powdery solid is aluminum oxide or boron nitride, it is observed whether peaks of aluminum (Al) or boron (B) are observed by surface analysis by ESCA, and the The presence or absence of surface exposure can be confirmed.

In the present invention, as the pressure-sensitive adhesive composition, those based on various rubbers or synthetic resins can be widely used, but from the viewpoint of long-term reliability, alkyl (meth) acrylate-based polymers are used. Is preferably used. The polymer can be synthesized by a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, or the like, but is preferably synthesized by a bulk polymerization method of irradiating an ultraviolet ray, an electron beam, or the like to perform polymerization. This eliminates problems such as corrosion of electronic components due to the residual organic solvent, swelling, peeling, and displacement due to vaporization and expansion at high temperatures, and concerns about contamination by emulsifier bleed, poor adhesion, and reduced moisture resistance. In addition, by irradiating relatively weak intensity ultraviolet light, etc., the molecular weight of the polymer can be increased, and it becomes possible to prepare a pressure-sensitive adhesive composition having a high degree of cross-linking and a large cohesive strength and excellent heat resistance. That's why.

When synthesizing a (meth) acrylic acid alkyl ester-based polymer, the number of carbon atoms of an alkyl group such as butyl acrylate, isononyl acrylate, isooctyl acrylate, or 2-ethylhexyl acrylate is used as a main monomer. Is an alkyl (meth) acrylate of 2 to 14. Further, as a modifying monomer copolymerizable with these main monomers, acrylic acid, itaconic acid, sulfopropyl acrylate, hydroxyalkyl acrylate, cyanoalkyl acrylate, acrylamide,
Substituted acrylamide, N-vinylcaprolactam, acrylonitrile, 2-methoxyethyl acrylate, glycidyl acrylate, caprolactone-modified acrylate,
Monomers such as caprolactan-modified hydroxyethyl acrylate, vinyl acetate and styrene are used alone or in combination of two or more.

The modifying monomer copolymerizable with the above-mentioned main monomer comprises 70 to 100% by weight, preferably 80% by weight of the main monomer.
% To 95% by weight, and 30 to 0 copolymerizable modifying monomer.
%, Preferably 20 to 5% by weight. The modifying monomer is used to improve adhesiveness and control the glass transition temperature of the polymer to improve cohesive strength and heat resistance. Good balance between properties and cohesion. In addition, as long as the adhesive properties are not adversely affected, oligomers of the above monomers, polyols and air
Commercially available oligomer thickeners such as telluride may be used as necessary.

In order to increase the shear strength, the main ingredient comprising an alkyl (meth) acrylate ester polymer includes tolylene diisocyanate, trimethylolpropane tolylene diisocyanate, diphenylmethane triisocyanate. Polyfunctional isocyanate-based crosslinking agents such as neat and diphenylmethane triisocyanate; epoxy-based crosslinking agents such as polyethylene glycol diglycidyl ether and trimethylolpropane triglycidyl ether; melamine resins A crosslinking agent, a metal salt-based crosslinking agent, a metal chelate-based crosslinking agent, an amino resin-based crosslinking agent, a peroxide-based crosslinking agent, and the like may be blended. The compounding amount is usually preferably 0.01 to 10 parts by weight per 100 parts by weight of the alkyl (meth) acrylate-based polymer as the main ingredient.

Also, as a cross-linking agent, a polyfunctional (meth)
Acrylate can also be used. Specifically, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, 1,2
-Ethylene glycol di (meth) acrylate, 1,6
Hexanediol (meth) acrylate and the like. These polyfunctional (meth) acrylates are used in an amount of 0.0
The amount is preferably 2 to 5 parts by weight, preferably 0.1 to 3 parts by weight. Within such a range, the number of functional groups may be large in the case of bifunctionality and small in the case of trifunctional or more functional groups.

In the pressure-sensitive adhesive composition used in the present invention, Al ₂ O ₃ , BN, SiO ₂ , T
iB ₂ , Si ₃ N ₄ , TiO ₂ , MgO, NiO, Cu
It is desirable to mix O, Fe ₂ O _{3 and the} like. The compounding amount is usually 10 parts by weight per 100 parts by weight of the polymer as the main agent.
It is good to be 300 parts by weight, preferably 10 to 120 parts by weight. The particle size is usually 0.5 to 250 μm, preferably 1 to 100 μm, more preferably 2 to 10 μm. Depending on the rheology of the monomer and the rheological properties of the final composition, various shapes such as spherical, needle-like, flake-like and star-like shapes can be selected. Purity is
In order to avoid an extreme increase in viscosity during preparation of the pressure-sensitive adhesive composition, it is preferably 95% by weight or more.

The pressure-sensitive adhesive composition used in the present invention may contain a silane coupling agent in order to further improve the adhesion between the support and the layer of the pressure-sensitive adhesive composition. A silane coupling agent is an organic silicon monomer having two or more different reactive groups in a molecule, one of the reactive groups is a reactive group that chemically bonds to an inorganic substance, and the other is an organic material. Is a reactive group that chemically bonds with Reactive groups that chemically bond with inorganic substances include methoxy, ethoxy, and silano groups.
Reactive groups that chemically bond with organic materials
Examples include a vinyl group, an epoxy group, a methacryl group, an amino group, and a mercapto group. The amount of the silane coupling agent used is usually preferably 0.01 to 20 parts by weight per 100 parts by weight of the polymer as the main agent.

The silane coupling agent includes vinyl trichlorosilane, vinyl tris (β-methoxyethoxy) silane, vinyl triethoxy silane, vinyl trimethoxy silane, γ-methacryloxypropyl trimethoxy silane, β- (3,4-epoxy Cyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-glycidoxypropyl Lutriethoxysilane, γ
-Methacryloxypropylmethyldiethoxysilane, γ
-Methacryloxypropylmethyldiethoxysilane, γ
-Methacryloxypropyltriethoxysilane, N-β
(Aminoethyl) γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane and the like. From these silane coupling agents, an appropriate one is selected in consideration of compatibility with the pressure-sensitive adhesive composition, viscosity increase, presence or absence of gelation, and the like.

The pressure-sensitive adhesive composition used in the present invention may further contain, in addition to the above components, a pigment, a filler, an antioxidant, and a tackifier within a range not to impair the adhesive performance and the effect of the present invention. Various known additives such as an agent and a flame retardant may be blended. In the present invention, by providing the layer of the pressure-sensitive adhesive composition configured as described above on the exposed surface of the powdery solid of the support, the form such as a sheet or a tape can be obtained. Heat-conductive pressure-sensitive adhesive sheets. The thickness of the layer of the pressure-sensitive adhesive composition provided on the support is generally preferably from 10 to 300 μm.

In the production of the heat-conductive pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive composition comprises a (meth) acrylic acid alkyl ester-based polymer as a main component, and this polymer is photopolymerized. In the case where the polymer is obtained by bulk polymerization, the polymerization may be performed as follows. First, a photopolymerization initiator is added to the main monomer or the modifying monomer copolymerizable therewith, and this is partially polymerized to have a viscosity of about 500 to 5,000.
Form a centrifugal syrup of 0 centipoise. If necessary, a polyfunctional (meth) acrylate, a thermally conductive filler, a silane coupling agent, an additional photopolymerization initiator, the above-mentioned various additive components, etc. may be mixed to form a photopolymerizable composition. It is prepared, applied to a release liner, and photo-polymerized by irradiation with ultraviolet or radiation to form a layer of a pressure-sensitive adhesive composition. By transferring this layer to the exposed surface of the support, the heat-conductive pressure-sensitive adhesive sheets can be obtained. Alternatively, the photopolymerizable composition may be directly applied to the exposed surface of the powdery and granular solid of the support and photopolymerized in the same manner as described above to form a layer of the pressure-sensitive adhesive composition.

The heat-conductive pressure-sensitive adhesive sheets of the present invention thus produced are excellent in heat conductivity and pressure-sensitive adhesiveness, and have an undercoat layer on the support which causes problems such as environmental deterioration. Despite the absence, the adhesiveness between the support and the layer of the pressure-sensitive adhesive composition is excellent, and there is no possibility of anchor breakage between the two. For this reason, when used for fixing various members, good holding performance is exhibited under high temperature use.

Using the heat conductive adhesive sheets of the present invention,
For example, to bond and fix electronic components and heat dissipation members,
The above-mentioned pressure-sensitive adhesive sheets may be interposed between the two, and a pressure-bonding process may be performed by utilizing the pressure-sensitive adhesive property, so that both have good thermal conductivity and good adhesion even at a high temperature. Can be fixed with strength.

The electronic components to be bonded and fixed are not particularly limited, but include, for example, IC chips, hybrid packages, multi-chip modules, power transistors, sealed integrated circuits made of plastic and metal, and the like. Is mentioned. INDUSTRIAL APPLICABILITY According to the present invention, the present invention can be advantageously applied to bonding and fixing of an electronic component having a large heat generation amount, such as a highly integrated IC circuit. The other heat-dissipating member to be bonded and fixed includes a heat sink made of a metal plate, a sheet-like material, or the like, or another heat sink. The thickness of the heat sink is generally 10 μm to 10 mm, preferably 100 μm to 3 mm, but is not limited thereto. The radiator may have an appropriate structure such as a form having a cooling fan.

The heat conductive pressure-sensitive adhesive sheets of the present invention are not limited to the above-mentioned adhesive fixing of the electronic component and the heat radiating member.
It can be used for purposes such as fixing various members such as building materials, vehicles, aircraft, and ships. Needless to say, even when used for these purposes, the same excellent effects as described above can be obtained.

[0032]

EXAMPLES Examples of the present invention will be described below in more detail. In the following, all parts are parts by weight.

Example 1 75 parts of isooctyl acrylate, 20 parts of butyl acrylate
Part, 5 parts of acrylic acid and 0.1 part of 2,2-dimethoxy-2-phenylacetone (photopolymerization initiator) were exposed to ultraviolet rays in a nitrogen gas atmosphere to partially polymerize the mixture, and the viscosity was about A coatable syrup of 40 poise was obtained. To 100 parts of this syrup, 0.2 parts of trimethylolpropane triacrylate (crosslinking agent) and 40 parts of boron nitride (BN) were added to prepare a photopolymerizable composition. This was applied on a release liner, and 900 m with a high-pressure mercury lamp having a light intensity of 5 mW / cm ² in a nitrogen gas atmosphere.
After irradiating ultraviolet rays of j / cm ² to carry out photopolymerization, it was dried at 130 ° C. for 5 minutes by a hot air circulating drier to have a thickness of 5
A 0 μm layer of the pressure sensitive adhesive composition was formed.

A 25 μm thick polyimide film containing 17% by volume of Al ₂ O ₃ was used as a support.
Both sides of this film were subjected to a sputter etching treatment (introduced gas: Ar). From the surface analysis of ESCA, it was confirmed that Al ₂ O ₃ was exposed on the treated surface, since peaks of Al were observed. This exposed surface (both sides)
Then, the above-mentioned layer of the pressure-sensitive adhesive composition having a thickness of 50 μm was laminated thereon to prepare a heat-conductive pressure-sensitive adhesive sheet having a total thickness of 125 μm.

Example 2 85 parts of 2-ethylhexyl acrylate, 5 parts of acrylic acid
Premix consisting of 10 parts of caprolactone-modified acrylate [“Alonix M-5300” manufactured by Toa Gosei Chemical Co., Ltd.] and 0.1 part of 2,2-dimethoxy-2-phenylacetone (photopolymerization initiator). Was exposed to ultraviolet light in a nitrogen atmosphere to partially polymerize, thereby obtaining a coatable syrup having a viscosity of about 40 poise. To 100 parts of this syrup, 0.2 parts of trimethylolpropane triacrylate (crosslinking agent) and 40 parts of boron nitride (BN) were added to prepare a photopolymerizable composition.

A 25 μm thick polyimide film containing 17% by volume of Al ₂ O ₃ was used as a support.
Both sides of this film were sandblasted. ESC
A surface analysis of A confirmed that Al ₂ O ₃ was exposed on the treated surface, since peaks of Al were observed. After applying the photopolymerizable composition to the exposed surface (both sides), the light intensity was 5 mW /
photopolymerized by irradiating ultraviolet rays of 900 mj / cm ² at cm ² of a high pressure mercury lamp. After that, 1
After drying at 30 ° C. for 5 minutes, a layer of the pressure-sensitive adhesive composition having a thickness of 50 μm was formed, and a heat-conductive pressure-sensitive adhesive sheet having a total thickness of 125 μm was prepared.

Example 3 95 parts of 2-ethylhexyl acrylate and 5 parts of acrylic acid were mixed in 210 parts of ethyl acetate under the coexistence of 0.4 part of 2,2-azobisisobutyronitrile and purging with nitrogen gas. 6
The solution was subjected to solution polymerization with stirring at 0 to 80 ° C. to give a viscosity of about 120 poise, a polymerization rate of 99.2% by weight, and a solid content of 30.
A polymer solution was obtained in a weight%. This polymer solution 1
To 00 parts, 3 parts of a polyfunctional isocyanate-based crosslinking agent, 40 parts of boron nitride (BN) and 0.2 part of γ-glycidoxypropylmethyldiethoxysilane were added, and a pressure-sensitive adhesive solution was added. Was prepared.

This pressure-sensitive adhesive solution was applied on a release liner, dried at 40 ° C. for 5 minutes with a hot air drier, and then dried at 130 ° C.
For 5 minutes to form a layer of the pressure-sensitive adhesive composition having a thickness of 50 μm. As a support, the same polyimide film having Al ₂ O ₃ exposed on both surfaces as in Example 1 was used, and a layer of the above-mentioned pressure-sensitive adhesive composition was adhered to the exposed surface (both surfaces) to give a total thickness of 125 μm. A heat conductive pressure-sensitive adhesive sheet was prepared.

Example 4 As a support, boron nitride (BN) produced by a cutting method
Of polytetrafluoroethylene film containing 18% by volume and having a thickness of 25 μm. The peak of B was observed in the surface analysis of ESCA, and it was confirmed that BN was exposed on both surfaces. A layer of the pressure-sensitive adhesive composition having a thickness of 50 μm formed in Example 1 was adhered to the exposed surfaces (both surfaces) to form a heat-conductive pressure-sensitive adhesive sheet having a total thickness of 125 μm.

Example 5 The same procedure as in Example 1 was repeated except that the layer of the pressure-sensitive adhesive composition was adhered to only one side of the polyimide film having Al ₂ O ₃ exposed on the surface. A 75 μm thermally conductive pressure sensitive adhesive sheet was made.

Comparative Example 1 As a support, a thickness not containing Al ₂ O ₃ was 25 μm.
A heat-conductive pressure-sensitive adhesive sheet having a total thickness of 125 μm was prepared in the same manner as in Example 1 except that the polyimide film was used.

Comparative Example 2 A heat conductive film having a total thickness of 125 μm was obtained in the same manner as in Example 1 except that the both sides of the polyimide film containing Al ₂ O ₃ used as the support were not subjected to sputter etching treatment. A pressure-sensitive adhesive sheet was prepared.

Comparative Example 3 The same as Example 4 except that a 25 μm-thick polytetrafluoroethylene film containing 18% by volume of boron nitride (BN) produced by a casting method was used as a support. Thus, a heat conductive pressure-sensitive adhesive sheet having a total thickness of 125 μm was produced. The above support film is made of ES
In the surface analysis of CA, no peak of B was observed, and it was confirmed that BN was not exposed on the film surface.

Each of the heat conductive pressure-sensitive adhesive sheets of Examples 1 to 5 and Comparative Examples 1 to 3 was subjected to the following method.
A constant load peel test and a thermal resistance test were performed. These results were as shown in Table 1 below.

<Constant Load Peeling Test> Each of the heat conductive pressure-sensitive adhesive sheets of Examples 1 to 4 and Comparative Examples 1 to 3 was used as a sample by backing a polyethylene terephthalate film having a thickness of 25 μm. . The heat conductive pressure-sensitive adhesive sheet of Example 5 was used as a sample. Each of these samples is 20mm wide
Into a test piece. The test piece was leveled so that the aluminum plate was positioned above, and a load (150
g) and left for 30 minutes in an atmosphere at 130 ° C., and then observed one moving distance (peeling distance) of the sample and its destruction state.

<Thermal Resistance Test> Transistors in the TO-220 package were bonded using a heat conductive pressure-sensitive adhesive sheet.
A pressure of 2 is applied to the heat sink that has been immersed in water and maintained at a constant temperature.
After the adhesive is fixed at Kg / cm ² , a fixed amount of output is supplied to the transistor, and the temperature difference (T2) between the transistor temperature (T2) and the surface temperature (T1) under the heat conductive pressure-sensitive adhesive sheet is obtained.
-T1) was measured. From this temperature difference, the thermal resistance was calculated according to the following equation. Thermal resistance (° C./cm ² / W) = (T ² −T 1) × A / P A: Transistor area (cm ² ) P: Transistor power consumption (W)

The temperature (T2) of the transistor was measured by a thermocouple spot-welded to the metal base of the transistor package. The surface temperature (T1) under the heat conductive pressure-sensitive adhesive sheet was measured by making a small hole in the heat sink and pushing a thermocouple. At that time, the thermocouple was held as close as possible so as not to affect the bonding area of the heat conductive pressure-sensitive adhesive sheet.

[0048]

As is clear from the results shown in Table 1 above, each of the heat conductive pressure-sensitive adhesive sheets of Examples 1 to 5 of the present invention had a small moving distance of 4 cm or less in a constant load peeling test and was broken. The state is cohesive failure, excellent adhesion between the support film and the layer of the pressure-sensitive adhesive composition, good holding performance even at high temperature use, and satisfactory thermal conductivity by thermal resistance test. You can see that it is what you are doing.

On the other hand, in each of the heat conductive pressure-sensitive adhesive sheets of Comparative Examples 1 to 3, the moving distance was as large as 15 cm or more in the constant load peeling test, and the breaking state was anchor breaking. It can be seen that the adhesion between the support film and the layer of the pressure-sensitive adhesive composition was poor, and the holding performance under high temperature use was extremely poor. Further, the heat conductive pressure-sensitive adhesive sheet of Comparative Example 1 is inferior in heat conductivity in a heat resistance test.

[0051]

As described above, according to the present invention, a plastic film containing a specific amount of a particulate solid and having the above-mentioned particulate solid exposed on the surface of the film is used as a support. By providing a layer of the pressure-sensitive adhesive composition on, even without providing an undercoat layer,
A heat conductive pressure-sensitive adhesive sheet with excellent adhesion between the support and the layer of the pressure-sensitive adhesive composition and excellent holding performance under high temperature use
Can provide. The heat conductive pressure-sensitive adhesive sheets are used for fixing electronic components, particularly, fixing electronic components to heat radiation members, and for fixing members in various fields such as construction materials, vehicles, aircraft, and ships. Can be widely used.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shigeki Muta 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation

Claims (6)

[Claims] A plastic film containing 2 to 50% by volume of a particulate solid is used as a support, and the above powdery solid is exposed on the surface of the support, and a layer of the pressure-sensitive adhesive composition is formed thereon. Thermal conductive pressure-sensitive adhesive sheets provided. 2. The heat conductive pressure-sensitive adhesive sheet according to claim 1, wherein the plastic film constituting the support comprises polyimide (amide). 3. The heat-conductive pressure-sensitive adhesive sheet according to claim 1, wherein the particulate solid is aluminum oxide or boron nitride.
Kind. 4. The heat-conductive pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive composition mainly comprises an alkyl (meth) acrylate-based polymer. 5. The heat-conductive pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive composition contains a heat-conductive filler. 6. The heat-conductive pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive composition contains a silane coupling agent.