Method of producing heat conductive sheet

Patent metadata

Field	Value
Publication number	US-2015144316-A1
Application number	US-201314402195-A
Country	US
Kind code	A1
Filing date	Jul 8, 2013
Priority date	Jul 7, 2012
Publication date	May 28, 2015
Grant date	—

Abstract

A method of producing a heat conductive sheet includes: a step (A) of dispersing a fibrous filler and a spherical filler in a binder resin to prepare a heat conductive sheet-forming composition; a step (B) of forming a molded block using the prepared heat conductive sheet-forming composition; a step (C) of slicing the formed molded block to a desired thickness to form a sheet; and a step (D) of pressing the sliced surface of the formed sheet, the sliced surface being pressed such that the thermal resistance value of the sheet after pressing becomes lower than the thermal resistance value of the sheet before pressing.

First claim

1 . A method of producing a heat conductive sheet, the method comprising the following Steps (A) to (D):
Step (A) a step of dispersing a fibrous filler and a spherical filler in a binder resin to prepare a heat conductive sheet-forming composition; Step (B) a step of forming a molded block using the prepared heat conductive sheet-forming composition; Step (C) a step of slicing the formed molded block to a desired thickness to form a sheet; and Step (D) a step of pressing a sliced surface of the formed sheet, the sliced surface being pressed such that a thermal resistance value of the sheet after pressing becomes lower than the thermal resistance value of the sheet before pressing, wherein the fibrous filler in the Step (A) is a carbon fiber having an average diameter of 8 to 12 μm and an aspect ratio of 2 to 50, amounts of the fibrous filler and the spherical filler added to the heat conductive sheet-forming composition are 16 to 40% by volume and 30 to 60% by volume, respectively, and a thermal resistance value (K·cm 2 /W) of the sheet before pressing that is formed in the Step (C) is controlled to 0.31 to 1.00.

2 . The production method according to claim 1 , wherein in the Step (B), the molded block is formed by an extrusion molding method or a die molding method.

3 . The production method according to claim 1 , wherein the binder resin in the Step (A) is a silicone resin.

4 . The production method according to claim 1 , wherein, when the sheet formed in the Step (C) has a thickness of less than 0.65 mm, the thermal resistance value (K·cm 2 /W) of the sheet before pressing is controlled to a range of more than 0.31 and less than 0.47.

5 . The production method according to claim 1 , wherein, when the sheet formed in the Step (C) has a thickness of 0.65 mm or more and 3 mm or less, the thermal resistance value (K·cm 2 /W) of the sheet before pressing is controlled to a range of more than 0.47 and less than 1.00.

6 . The production method according to claim 1 , wherein, a pressure applied to the sheet in the Step (D) is 1 to 8 kgf/cm 2 .

7 . The production method according to claim 1 , wherein, when a spacer is used, the pressing is performed in the Step (D) at a set pressure of 0.1 to 30 MPa.

8 . The production method according to claim 1 , wherein the pressing is performed in the Step (D) while heating at a glass transition temperature of the binder resin or higher.

9 . The production method according to claim 1 , wherein the pressing is performed in the Step (D) so that a compression ratio of the sheet is 2 to 15%.

10 . The production method according to claim 1 , wherein the pressing is performed in the Step (D) such that a glossiness (gloss value) of the surface of the sheet after pressing is 0.1 or higher.

11 . A heat conductive sheet obtained by the production method according to claim 1 .

12 . The heat conductive sheet according to claim 11 , wherein a random orientation ratio of the fibrous filler in the molded block molded in the Step (B) is 55 to 95%.

13 . A thermal device comprising: a heat generating body; a heat dissipator; and the heat conductive sheet according to claim 11 , the heat conductive sheet disposed therebetween.

14 . A heat conductive sheet produced by pressing a sheet formed from a molded block composed of a heat conductive sheet-forming composition, wherein
the heat conductive sheet-forming composition is prepared by dispersing a fibrous filler and a spherical filler in a binder resin, the fibrous filler is a carbon fiber having an average diameter of 8 to 12 μm and an aspect ratio of 2 to 50, the heat conductive sheet-forming composition contains 16 to 40% by volume of the fibrous filler and 30 to 60% by volume of the spherical filler, and a random orientation ratio of the fibrous filler in the molded block is controlled within a range of 55 to 95%, whereby a thermal resistance value (K·cm 2 /W) of the sheet before pressing that is formed from the molded block is in a range of 0.31 to 1.00.

Assignees

• Dexerials Corp

Inventors

• Aramaki Keisuke

Classifications

• H10W70/027

  Mechanical treatments, e.g. deforming, punching or cutting · CPC title

• H10W40/251

  Organics · CPC title

• C08J2383/07

  containing silicon bound to unsaturated aliphatic groups · CPC title

• B29K2995/0013

  Conductive · CPC title

• B29D7/01

  Films or sheets · CPC title