Thermally conductive flexible adhesive for aerospace applications

Patent metadata

Field	Value
Publication number	US-2018265751-A1
Application number	US-201815987809-A
Country	US
Kind code	A1
Filing date	May 23, 2018
Priority date	Feb 25, 2014
Publication date	Sep 20, 2018
Grant date	—

Abstract

Provided are methods of forming thermally conductive flexible bonds for use in electronic boards of unmanned spacecraft and other types of aircraft. Also provided are methods of preparing adhesive materials to form these bonds including methods of preparing treated filler particles. In some aspects, an adhesive material includes filler particles having organofunctional groups, such as boron nitride particles treated in silane. These particles may be combined with a urethane modified epoxy to form the adhesive material. The weight ratio of the particles in the adhesive material may be about 40-60%. The adhesive material may be thermally cured using a temperature of less than 110° C. to prevent damage to bonded electronic components. The cured adhesive may have a thermal conductivity of at least about 2 W/m K measured in vacuum and may have a glass transition temperature if less than −40° C.

First claim

What is claimed is:

1 . A method of preparing a thermally conductive flexible adhesive material, the method comprising:
combining a urethane modified epoxy with boron nitride particles thereby forming a combined material,
wherein a concentration of the boron nitride particles in the combined material is between 20% by weight and 70% by weight,
wherein an average aspect ratio between any two dimensions of the boron nitride particles is less than 5,
wherein the boron nitride particles comprise a silane, comprising organofunctional groups, attached to a surface of the boron nitride particles; and
mixing the combined material to form the thermally conductive flexible adhesive material.

2 . The method of claim 1 , wherein mixing the combined material is performed using a dual asymmetric centrifugal mixer.

3 . The method of claim 1 , further comprising freezing the thermally conductive flexible adhesive material.

4 . The method of claim 1 , wherein the thermally conductive flexible adhesive material has a viscosity of at least 100,000 cP after mixing.

5 . The method of claim 1 , wherein the thermally conductive flexible adhesive material has a viscosity of at least 500,000 cP after mixing.

6 . The method of claim 1 , further comprising, prior to combining the urethane modified epoxy with the boron nitride particles, mixing a base resin of the urethane modified epoxy with a hardener of the urethane modified epoxy.

7 . The method of claim 1 , wherein the concentration of the boron nitride particles in the combined material is between 40% by weight and 60% by weight.

8 . The method of claim 1 , wherein mixing the combined material comprises controlling temperature of the combined material.

9 . The method of claim 8 , wherein the temperature of the combined material is kept below 60° C. while mixing the combined material.

10 . The method of claim 1 , wherein mixing the combined material is performed in stages, with a cooling break between two adjacent one of the stages.

11 . The method of claim 1 , wherein an average particle size of the boron nitride particles is between 10 micrometers and 200 micrometers.

12 . The method of claim 1 , wherein the organofunctional groups are selected from the group consisting of glycidyl groups and alcohol functional groups.

13 . The method of claim 1 , wherein the organofunctional groups and represented by a formula C 2 OH 3 R, where R is O(CH 2 ) n and where n is between 1 and 5.

14 . The method of claim 13 , wherein n in O(CH 2 ) n is between 2 and 4.

15 . The method of claim 1 , wherein n in O(CH 2 ) n is 3.

16 . The method of claim 1 , wherein the silane, comprising the organofunctional groups, is (3-glycidyloxypropyl) trimethoxysilane.

17 . The method of claim 1 , wherein the organofunctional groups are covalently bound to the surface of the boron nitride particles.

18 . The method of claim 1 , further comprising:
applying the thermally conductive flexible adhesive material onto a surface of an electronic board; forming a contact between an electronic component and the thermally conductive flexible adhesive material applied to the surface of the electric board; and curing the thermally conductive flexible adhesive material thereby forming a cured adhesive structure between the electric board and the electronic component.

19 . The method of claim 18 , wherein the cured adhesive structure provides a thermally conductive flexible bond between the electric board and the electronic component.

20 . The method of claim 18 , wherein the cured adhesive structure at least partially encapsulates the electronic component.

Assignees

• Boeing Co

Inventors

• Babilo Peter
• Moss Randall Jay

Classifications

• B29K2509/04

  Carbides; Nitrides · CPC title

• C09J2203/326

  for bonding electronic components such as wafers, chips or semiconductors · CPC title

• B32B37/1284

  Application of adhesive · CPC title

• C07F7/1804

  Compounds having Si-O-C linkages (Si-O-acyl linkages C07F7/1896) · CPC title

• B29C65/4855

  characterised by their physical properties, e.g. being electrically-conductive · CPC title