Thermally conductive sheet

Patent metadata

Field	Value
Publication number	US-2021130561-A1
Application number	US-201816480851-A
Country	US
Kind code	A1
Filing date	Jan 16, 2018
Priority date	Jan 26, 2017
Publication date	May 6, 2021
Grant date	—

Abstract

A thermally conductive sheet in which a cured layer of a thermally conductive silicone composition is laminated on one or both sides of a synthetic resin film layer of aromatic polyimide, etc. having excellent heat resistance, electrical insulation, and mechanical strength, wherein good thermal conductivity, good insulation, and strong interlayer adhesion are provided because the thermally conductive silicone composition includes 250 to 600 wt. % of an aspherical thermally conductive filler material, which contains no more than 80 ml/100 g of a DOP oil absorption amount and an organic silicon compound component including an adhesion imparting agent, relative to 100 wt. % of the organic silicon compound component, and moreover the thermally conductive sheet with no brittleness during use can be made using continuous molding.

First claim

1 . A thermally conductive sheet comprising an electrically insulating synthetic resin film layer and, on one or both sides of the synthetic resin film layer, a cured layer of a thermally conductive silicone composition, wherein the thermally conductive silicone composition comprises an adhesion-imparting agent-containing organosilicon compound component and a non-spherical thermally conductive filler, the thermally conductive filler being included in an amount of from 250 to 600 parts by weight per 100 parts by weight of the organosilicon compound component and having a DOP oil absorption of 80 mL/100 g or less.

2 . The thermally conductive sheet of claim 1 , wherein the synthetic resin used in the synthetic resin film layer has a melting point of at least 100° C.

3 . The thermally conductive sheet of claim 1 , wherein the synthetic resin used in the synthetic resin film layer is an aromatic polyimide, a polyamide, a polyamide-imide, a polyester, a polyolefin, an aromatic polyether, a fluoropolymer, or a combination of two or more thereof.

4 . The thermally conductive sheet of claim 1 , wherein the adhesion-imparting agent in the thermally conductive silicone composition is a silicon compound-based adhesion-imparting agent having an epoxy group and/or an alkoxy group, and also having at least one group selected from a vinyl group and a group of the formula Si—H.

5 . The thermally conductive sheet of claim 4 , wherein the adhesion-imparting agent is selected from silicon compounds of the following formulas.

6 . The thermally conductive sheet of claim 1 , wherein the non-spherical thermally conductive filler in the thermally conductive silicone composition is aluminum hydroxide powder.

7 . The thermally conductive sheet of claim 6 , wherein the aluminum hydroxide powder comprises:
(1) from 100 to 500 parts by weight of an aluminum hydroxide powder having an average particle size of from 5 to 14 μm and a DOP oil absorption of 50 mL/100 g or less, and (2) from 50 to 400 parts by weight of an aluminum hydroxide powder having an average particle size of from 0.5 to 3 μm and a DOP oil absorption of 80 mL/100 g or less;
with (1) accounting for at least 40 wt % of the overall amount of non-spherical thermally conductive filler.

8 . The thermally conductive sheet of claim 1 , wherein the non-spherical thermally conductive filler in the thermally conductive silicone composition has an amount of particles at least 45 μm in size of from 0 to 0.5 wt % and an amount of particles at least 75 μm in size of from 0 to 0.01 wt %.

9 . The thermally conductive sheet of claim 1 , wherein the organosilicon compound component in the thermally conductive silicone composition comprises:
(A) an organopolysiloxane of average compositional formula (1) below
R 1 a SiO (4-a)/2   (1)

(wherein each R 1 is independently a substituted or unsubstituted monovalent hydrocarbon group of 1 to 10 carbon atoms, and the subscript ‘a’ is from 1.90 to 2.05) which has at least two silicon-bonded alkenyl groups per molecule.

10 . The thermally conductive sheet of claim 9 , wherein the organosilicon compound component in the thermally conductive silicone composition further comprises (E) from 0.01 to 30 wt %, based on the total amount of the organosilicon compound component in the thermally conductive silicone composition, of one or more selected from:
(E1) alkoxysilanes of general formula (2) below
R 2 b R 3 c Si(OR 4 ) 4-b-c   (2)

(wherein each R 2 is independently an alkyl group of 6 to 15 carbon atoms, each R 3 is independently a substituted or unsubstituted monovalent hydrocarbon group of 1 to 12 carbon atoms, each R 4 is independently an alkyl group of 1 to 6 carbon atoms, b is an integer from 1 to 3, c is 0, 1 or 2, and the sum b+c is from 1 to 3), and (E2) dimethylpolysiloxanes of general formula (3) below

(wherein each R is independently an alkyl group of 1 to 6 carbon atoms, and d is an integer from 5 to 100) that are capped at one end with a trialkoxysilyl group.

11 . The thermally conductive sheet of claim 9 , wherein the thermally conductive silicone composition further comprises, as (C) a curing agent:
(C-1a) an organohydrogenpolysiloxane in an amount such that the total amount of silicon-bonded hydrogen atoms in the thermally conductive silicone composition per mole of the total amount of alkenyl groups in the thermally conductive silicone composition falls in the range of 0.8 to 10 moles; and (C-1b) a platinum catalyst in an amount such that the level of platinum metal in the platinum catalyst with respect to component (A), expressed in weight units, is from 0.1 to 2,000 ppm.

12 . The thermally conductive sheet of claim 9 , wherein the thermally conductive silicone composition further comprises, as (C) a curing agent:
(C-2) from 0.5 to 30 parts by weight of an organic peroxide per 100 parts by weight of the total amount of vinyl group-containing compounds in the thermally conductive silicone composition.

13 . The thermally conductive sheet of claim 1 , wherein the electrically insulating synthetic resin film layer has a thickness of from 5 to 90 μm, the cured layer of the thermally conductive silicone composition has a thickness of from 40 to 400 μm, and the overall thermally conductive sheet has a thickness of from 55 to 500 μm.

14 . The thermally conductive sheet of claim 1 , wherein the thermally conductive silicone composition, when cured, has a thermal conductivity of at least 1.2 W/m·K.

15 . The thermally conductive sheet of claim 1 , which has a dielectric breakdown voltage in air, as measured according to JIS K6249, of at least 2 kV.

Assignees

• Shinetsu Chemical Co

Inventors

• Endo Akihiro
• Ishihara Yasuhisa
• Yamaguchi Hisaharu
• Moteki Masahiro

Classifications

• H10W40/251 Primary

  Organics · CPC title

• H10W40/255

  having a laminate or multilayered structure, e.g. direct bond copper [DBC] ceramic substrates · CPC title

• H10W40/25

  characterised by their materials · CPC title

• H10W99/00

  Subject matter not provided for in other groups of this subclass · CPC title

• C08K2003/2227

  of aluminium · CPC title