Method of preparing thermally conductive compounds by liquid metal bridged particle clusters

• US 6,339,120 B1
• Filed: 04/05/2000
• Issued: 01/15/2002
• Est. Priority Date: 04/05/2000
• Status: Expired due to Term

• Current Assignee: Henkel IP & Holding GmbH (Henkel AG & Co KGaA)
• Original Assignee: Berquist Company The (Henkel AG & Co KGaA)
• Inventors: Olson, Richard M., Misra, Sanjay
• Primary Examiner(s): Cain, Edward J.
• Application Number:
  US09/543,661
• Time in Patent Office: 650 Days
• Field of Search: 524/404, 524/434, 524/439
• US Class Current: 524/404
• CPC Class Codes: F28F 2013/006 Heat conductive materials
• CPC Class Codes: H01L 2224/2929 with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
• CPC Class Codes: H01L 2224/29386 with a principal constituent of the material being a non metallic, non metalloid inorganic material
• CPC Class Codes: H01L 2224/294 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 23/3736 Metallic materials H01L23/3732, H01L23/3733, H01L23/3735, H01L23/3737, H01L23/3738 take precedence
• CPC Class Codes: H01L 23/3737 Organic materials with or without a thermoconductive filler
• CPC Class Codes: H01L 24/29 of an individual layer connector
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/01322 Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/014 Solder alloys
• CPC Class Codes: H01L 2924/0665 Epoxy resin
• CPC Class Codes: H01L 2924/15747 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2924/3011 Impedance

Abstract

A thermally conductive mechanically compliant pad including a quantity of gallium and/or indium alloy liquid at temperatures below about 120° C. and a boron nitride particulate solid blended into the liquid metal alloy to form a paste. The paste is then combined with a quantity of a flowable plastic resin such as silicone oil to form the mechanically compliant pad, the compliant pad comprising from between about 10% and 90% of metallic coated particulate, balance flowable plastic resin.

Claims

1. A method of preparing thermally conductive mechanically compliant pads comprising the steps of:

(a) preparing a mixture of;

(1) a quantity of a gallium and/or indium containing alloy which is in liquid state temperatures below 120°

C.;

(2) a thermally conductive particulate solid consisting essentially of boron nitride;

(b) mechanically blending said mixture to cause the surfaces of said particulate to become wetted with said liquid alloy to form a homogeneous paste wherein said liquid alloy encapsulates individual of said boron nitride particles;

(c) combining said paste with a quantity of a flowable plastic resin material to form a thermally conductive mass with said thermally conductive mass comprising from between about 10% and 90% by volume of metal coated particulate, balance flowable plastic resin.

2. The method of claim 1 wherein the particles making up said thermally conductive particulate solid have a diameter of between about 1 microns and 40 microns.

3. The method of claim 1 wherein said liquid alloy substantially encapsulates the particles to form a coating thereon, typically liquid metal to particle volume ratio being at least 1:

1 to obtain good thermal performance.

4. The method of claim 1 wherein said homogeneous paste is further blended with silicone resin to form a conformable pad, with the pad comprising between about 10% and 90% by volume of homogeneous paste, balance polysiloxane.

5. The method of claim 1 being particularly characterized in that said liquid metal alloy is in liquid state at temperatures below 60°

C.

6. The compliant thermally conductive pad prepared in accordance with the steps of claim 1.

7. The method of preparing thermally conductive mechanically compliant pads comprising the steps of:

(a) preparing a mixture of;

(1) a liquid metal alloy with a component selected from the group consisting of gallium and indium, and being in the liquid state at temperatures below 120°

C.; and

(2) a thermally conductive particulate solid selected from the group consisting of boron nitride, aluminum nitride, and alumina;

(b) mechanically blending said mixture to cause the surfaces of said particulate to become wetted with said liquid alloy to form a homogeneous paste wherein said liquid alloy encapsulates individual of said particles comprising said particulate;

(c) combining said paste with a quantity of a flowable plastic resin material to form a thermally conductive mass with said thermally conductive mass comprising from between about 10% and 90% by volume of metal coated particulate, balance flowable plastic resin.