# US 10,370,575 B2 · Thermally conductive sheet

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- Number: US 10,370,575 B2
- Document ID: US10370575B2
- Status: Granted
- Kind: B2
- Application number: 15/315,149
- Filed: 2015-05-25
- Published: 2017-07-13
- Granted: 2019-08-06
- Earliest claimed: 2014-06-10
- Assignees: Shin-Etsu Chemical Co., Ltd.
- Applicants: Shin-Etsu Chemical Co., Ltd.
- Inventors: Yasuhisa Ishihara; Akihiro Endo; Takahiro Maruyama
- Web page: https://patentgrep.com/patent/US10370575B2

## CPC

- C09K 5/14: Solid materials, e.g. powdery or granular
- C08K 7/18: inorganic
- C08L 83/04: Polysiloxanes
- C09D 183/04: Polysiloxanes
- H05K 7/20: Modifications to facilitate cooling, ventilating, or heating
- H10W 40/10: Arrangements for heating
- H10W 40/25: characterised by their materials
- H10W 40/251: {Organics}
- H10W 40/255: {having a laminate or multilayered structure, e.g. direct bond copper [DBC] ceramic substrates}
- C08K 3/22: of metals
- C08K 2003/2227: {of aluminium}
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A thermally conductive sheet including a glass cloth filled with a thermally conductive resin composition, one or both surfaces of the glass cloth being layered with a cured, thermally conductive silicone composition, wherein the thermally conductive silicone composition comprises a silicone component and thermally conductive filler (C) of an amount of 1,200 to 2,000 parts by mass, relative to 100 parts by mass of the silicone component, the thermally conductive filler (C) has an average particle size smaller than 15 μm, and an amount of particles having a particle size of 45 μm or larger is 0 to 3 mass % and an amount of particles having a particle size of 75 μm or larger is 0 to 0.01 mass %, based on an amount of the thermally conductive filler (C).

## Claims

### Claim 1

A thermally conductive sheet consisting of
a glass cloth filled with a thermally conductive resin composition, and
a cured thermally conductive silicone composition on one or both surfaces of the glass cloth, wherein
the thermally conductive silicone composition comprises a silicone component and thermally conductive filler (C) of an amount of 1,200 to 2,000 parts by mass, relative to 100 parts by mass of the silicone component,
the thermally conductive filler (C) has an average particle size smaller than 15 μm,
an amount of particles having a particle size of 45 μm or larger is 0 to 3 mass % and an amount of particles having a particle size of 75μm or larger is 0 to 0.01 mass %, based on an amount of the thermally conductive filler (C), and
the cured thermally conductive silicone composition has a hardness of 85 to 96, as determined by a type A durometer.

### Claim 2 (depends on 1)

The thermally conductive sheet according to claim 1, wherein the cured thermally conductive silicone composition has a thermal conductivity of 3.0 W/m·K or larger.

### Claim 3 (depends on 1)

The thermally conductive sheet according to claim 1, wherein the thermally conductive sheet having a total thickness of 0.2 mm has a thermal resistance of 1.8 cm2·K/W or less, as determined according to the ASTM D5470 standards.

### Claim 4 (depends on 1)

The thermally conductive sheet according to claim 1, wherein the thermally conductive sheet having a total thickness of 0.2 mm has a dielectric breakdown voltage of 6 kV or higher, as determined according to the Japanese Industrial Standards (JIS) K 6249.

### Claim 5 (depends on 1)

The thermally conductive sheet according to claim 1, wherein a thickness of the glass cloth is 60 μm or smaller in a cross section of the thermally conductive sheet, a thickness of the whole thermally conductive sheet is 130 to 900 μm when the sheet has the cured thermally conductive silicone composition on the both surfaces of the glass cloth, or a thickness of the whole thermally conductive sheet is 80 to 500 μm when the sheet has the cured thermally conductive silicone composition on one surface of the glass cloth.

### Claim 6 (depends on 1)

The thermally conductive sheet according to claim 1, wherein the silicone component comprises an organopolysiloxane (A) which has at least two alkenyl groups each bonded to a silicon atom and has the following average compositional formula:
R1aSiO(4-a)/2
wherein R1 is, independently of each other, substituted or unsubstituted, monovalent hydrocarbon group having 1 to 10 carbon atoms and a is 1.90 to 2.05.

### Claim 7 (depends on 6)

The thermally conductive sheet according to claim 6, wherein the silicone component further comprises
(D) at least one of the following (D1) or (D2):
(D1) an alkoxy silane represented by the following formula (1):
R2aR3bSi(OR4)4-a-b (1)
wherein R2 is, independently of each other, an alkyl group having 6 to 15 carbon atoms, R3 is, independently of each other, a substituted or unsubstituted, monovalent hydrocarbon group having 1 to 12 carbon atoms, R4 is, independently of each other, an alkyl group having 1 to 6 carbon atoms, a is an integer of from 1 to 3, and b is an integer of from 0 to 2, provided that a total of a and b is 1 to 3; or
(D2) a dimethylpolysiloxane in which one terminal is capped with a trialkoxysilyl group and which is represented by the following formula (2):
wherein R5 is, independently of each other, an alkyl group having 1 to 6 carbon atoms and c is an integer of from 5 to 100.

### Claim 8 (depends on 7)

The thermally conductive sheet according to claim 7, wherein an amount of component (D) is 0.01 to 60 mass %, based on a total amount of the silicone component.

### Claim 9 (depends on 1)

The thermally conductive sheet according to claim 1, wherein the thermally conductive filler (C) consists of 20 to 50 mass % of alumina (C1) which has an average particle size of at least 0.1 μm and smaller than 5 μm, and 50 to 80 mass % of alumina (C2) which has an average particle size of at least 5 μm and smaller than 15 μm.

### Claim 10 (depends on 9)

The thermally conductive sheet according to claim 9, wherein component (C2) is spherical alumina.

### Claim 11

A thermally conductive sheet consisting of
a glass cloth filled with a thermally conductive resin composition, and
a cured, cured thermally conductive silicone composition on one or both surfaces of the glass cloth, wherein
the thermally conductive silicone composition comprises a silicone component and thermally conductive filler (C) of an amount of 1,200 to 2,000 parts by mass, relative to 100 parts by mass of the silicone component,
the thermally conductive filler (C) has an average particle size smaller than 15 μm,
an amount of particles having a particle size of 45 μm or larger is 0 to 3 mass % and an amount of particles having a particle size of 75 μm or larger is 0 to 0.01 mass %, based on an amount of the thermally conductive filler (C), and
the silicone component comprises:
an organopolysiloxane (A) which has at least two alkenyl groups each bonded to a silicon atom and has the following average compositional formula:
R1aSiO(4-a)/2
wherein R1 is, independently of each other, substituted or unsubstituted, monovalent hydrocarbon group having 1 to 10 carbon atoms and a is 1.90 to 2.05; and
(D) at least one of the following (D1) or (D2):
(D1) an alkoxy silane represented by the following formula (1):
R2aR3bSi(OR4)4-a-b (1)
wherein R2 is, independently of each other, an alkyl group having 6 to 15 carbon atoms, R3 is, independently of each other, a substituted or unsubstituted, monovalent hydrocarbon group having 1 to 12 carbon atoms, R4 is, independently of each other, an alkyl group having 1 to 6 carbon atoms, a is an integer of from 1 to 3, and b is an integer of from 0 to 2, provided that a total of a and b is 1 to 3; or
(D2) a dimethylpolysiloxane in which one terminal is capped with a trialkoxysilyl group and which is represented by the following formula (2):
wherein R5 is, independently of each other, an alkyl group having 1 to 6 carbon atoms and c is an integer of from 5 to 100.

### Claim 12 (depends on 11)

The thermally conductive sheet according to claim 11, wherein the cured thermally conductive silicone composition has a hardness of 60 to 96, as determined by a type A durometer.

### Claim 13 (depends on 11)

The thermally conductive sheet according to claim 11, wherein the cured thermally conductive silicone composition has a thermal conductivity of 3.0 W/m·K or larger.

### Claim 14 (depends on 11)

The thermally conductive sheet according to claim 11, wherein the thermally conductive sheet having a total thickness of 0.2 mm has a thermal resistance of 1.8 cm2·K/W or less, as determined according to the ASTM D5470 standards.

### Claim 15 (depends on 11)

The thermally conductive sheet according to claim 11, wherein the thermally conductive sheet having a total thickness of 0.2 mm has a dielectric breakdown voltage of 6 kV or higher, as determined according to the Japanese Industrial Standards (JIS) K 6249.

### Claim 16 (depends on 11)

The thermally conductive sheet according to claim 11, wherein a thickness of the glass cloth is 60 μm or smaller in a cross section of the thermally conductive sheet, a thickness of the whole thermally conductive sheet is 130 to 900 μm when the sheet has the cured thermally conductive silicone composition on the both surfaces of the glass cloth, or a thickness of the whole thermally conductive sheet is 80 to 500 μm when the sheet has the cured thermally conductive silicone composition on one surface of the glass cloth.

### Claim 17 (depends on 11)

The thermally conductive sheet according to claim 11, wherein the thermally conductive filler (C) consists of 20 to 50 mass % of alumina (C1) which has an average particle size of at least 0.1 μm and smaller than 5 μm, and 50 to 80 mass % of alumina (C2) which has an average particle size of at least 5 μm and smaller than 15 μm.

### Claim 18 (depends on 17)

The thermally conductive sheet according to claim 17, wherein component (C2) is spherical alumina.

### Claim 19 (depends on 11)

The thermally conductive sheet according to claim 11, wherein an amount of component (D) is 0.01 to 60 mass %, based on a total amount of the silicone component.