Thermally conductive sheet, method for producing same, and semiconductor device

Patent metadata

Field	Value
Publication number	US-9966324-B2
Application number	US-201414892724-A
Country	US
Kind code	B2
Filing date	Jun 18, 2014
Priority date	Jun 27, 2013
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

A thermally conductive sheet, which contains: a binder; carbon fibers; and an inorganic filler, wherein the thermally conductive sheet is to be sandwiched between a heat source and a heat dissipation member of a semiconductor device, wherein the carbon fibers have an average fiber length of 50 μm to 250 μm, wherein thermal resistance of the thermally conductive sheet is less than 0.17 K·cm 2 /W, as measured in accordance with ASTM-D5470 with a load of 7.5 kgf/cm 2 , and wherein the thermally conductive sheet has an average thickness of 500 μm or less.

First claim

What is claimed is:

1. A thermally conductive sheet, comprising:
a binder;
carbon fibers; and
an inorganic filler,
wherein the thermally conductive sheet is to be sandwiched between a heat source and a heat dissipation member of a semiconductor device,
wherein the carbon fibers have an average fiber length of 50 μm to 250 μm,
wherein an amount of the carbon fibers in the thermally conductive sheet is 20% by volume to 40% by volume,
wherein an amount of the inorganic filler in the thermally conductive sheet is 30% by volume to 55% by volume,
wherein the inorganic filler contains alumina and aluminum nitride,
wherein the alumina has an average particle diameter of 4 μm to 5 μm,
wherein the aluminium nitride has an average particle diameter of 0.5 μm to 1.5 μm,
wherein the thermally conductive sheet having the component which shows that:
i) thermal resistance of average thickness of 400 μm or less indicates higher value than that of average thickness of 500 μm under the condition of the load of 1.0 kgf/cm 2 measured by ASTM-D5470; and
ii) thermal resistance of average thickness of 400 μm or less indicates lower value than that of average thickness of average thickness of 500 μm under the condition of the load of 7.5 kgf/cm 2 measured by ASTM-D5470;
in case when two thermally conductive sheets having average thickness of 500 μm and 400 μm or less of which components of thermally conductive sheet are the same but only their average thickness is different are prepared,
wherein thermal resistance of the thermally conductive sheet is less than 0.17 K·cm 2 /W, as measured in accordance with ASTM-D5470 with a load of 7.5 kgf/cm 2 , and
wherein the thermally conductive sheet has the average thickness of 400 μm or less.

2. The thermally conductive sheet according to claim 1 , wherein the thermal resistance of the thermally conductive sheet is 0.20 K·cm 2 /W or less, as measured in accordance with ASTM-D5470 with a load in the range of 2.0 kgf/cm 2 to 7.5 kgf/cm 2 .

3. The thermally conductive sheet according to claim 1 , wherein part of the carbon fibers is aligned at a surface of the thermally conductive sheet in a manner that major axes of the carbon fibers are aligned along an in-plane direction of the thermally conductive sheet.

4. The thermally conductive sheet according to claim 1 , wherein the average thickness (μm) of the thermally conductive sheet is greater than the average fiber length (μm) of the carbon fibers.

5. A method for producing the thermally conductive sheet according to claim 1 , the method comprising:
extruding a thermally conductive composition containing a binder precursor, carbon fibers, and an inorganic filler using an extruder, to obtain an extrusion-molded product;
curing the extrusion-molded product, to obtain a cured product; and
cutting the cured product in a vertical direction relative to a direction of the extruding.

6. A semiconductor device, comprising:
a heat source;
a heat dissipation member; and
a thermally conductive sheet, which is sandwiched between the heat source and the heat dissipation member,
wherein the thermally conductive sheet is the thermally conductive sheet according to claim 1 .

Assignees

• Dexerials Corp

Inventors

• Aramaki Keisuke
• Yoshinari Atsuya
• Ishii Takuhiro
• Uchida Shin-Ichi
• Ito Masahiko
• Uchida Syunsuke

Classifications

• H10W70/02

  of conductive package substrates serving as an interconnection, e.g. of metal plates (manufacture or treatment of leadframes H10W70/04) · CPC title

• H10W40/257

  having a heterogeneous or anisotropic structure, e.g. powder or fibres in a matrix, wire mesh or porous structures (H10W40/254, H10W40/251 take precedence) · CPC title

• H10W40/25

  characterised by their materials · CPC title

• H10W40/251 Primary

  Organics · CPC title

• H01L23/373

  Electricity · mapped topic