Thermally-capacitive phase change encapsulant for electronic devices

• US 6,703,128 B2
• Filed: 02/15/2002
• Issued: 03/09/2004
• Est. Priority Date: 02/15/2002
• Status: Expired due to Term

• Current Assignee: Delphi Technologies Ip Limited (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Burns, Jeffrey H., Chaudhuri, Arun K., Myers, Bruce A.
• Primary Examiner(s): Dawson, Robert
• Assistant Examiner(s): Zimmer, Marc S.
• Application Number:
  US10/075,981
• Publication Number:
  US 20030157342A1
• Time in Patent Office: 753 Days
• Field of Search: 428/402, 428/403, 428/407, 524/439, 524/440, 524/588
• US Class Current: 428/403
• CPC Class Codes: H01L 23/29 characterised by the material , e.g. carbon interlayer dielectrics H01L23/5329
• CPC Class Codes: H01L 23/295 containing a filler H01L23/296 takes precedence
• CPC Class Codes: H01L 23/3733 having a heterogeneous or anisotropic structure, e.g. powder or fibres in a matrix, wire mesh, porous structures H01L23/3732, H01L23/3737 take precedence
• CPC Class Codes: H01L 23/4275 by melting or evaporation of solids
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: Y10T 428/2991 Coated
• CPC Class Codes: Y10T 428/2998 including synthetic resin or polymer
• CPC Class Codes: Y10T 428/31663 As siloxane, silicone or silane

Abstract

An encapsulation material suitable for dissipating heat generated by an electronic module, such as by directly contacting a heat-generating power device or contacting a heat sink of a heat-generating power device. The encapsulation material comprises phase change particles dispersed in a gel material. The phase change particles preferably comprise a solder alloy encapsulated by a dielectric coating so the phase change particles are electrically insulated from each other. The encapsulation material may further comprise dielectric particles dispersed in the gel material for the purpose of increasing the thermal conductivity of the encapsulation material. Alternatively or in addition, the dielectric coating on the phase change particles may comprise dielectric particles that are dispersed in a dielectric matrix, again with the preferred effect of increasing the thermal conductivity of the encapsulation material.

Claims

1. An encapsulation material for an electronic module, the encapsulation material comprising:

a polymer matrix material; and

electrically-conductive phase change particles dispersed in the matrix material, the phase change particles being encapsulated by a dielectric coating so as to be electrically insulated from each other;

wherein the dielectric coating is a polymer capable of containing the phase change particles when molten.

4. The encapsulation material according to claim 1, further comprising dielectric particles dispersed in the matrix material, the dielectric particles having a higher coefficient of thermal conductivity than the matrix material.

5. The encapsulation material according to claim 4, wherein the dielectric particles are formed of a ceramic material.

6. The encapsulation material according to claim 4, wherein the dielectric coating comprises second dielectric particles dispersed in a dielectric matrix, the second dielectric particles being smaller than the dielectric particles dispersed in the matrix material.

7. The encapsulation material according to claim 6, wherein the second dielectric particles are formed of a ceramic material having a higher coefficient of thermal conductivity than the matrix material.

11. The encapsulation material according to claim 1, wherein the encapsulation material contacts a heat-generating power device.

12. The encapsulation material according to claim 1, wherein the encapsulation material contacts a heat sink of a heat-generating power device.

2. An encapsulation material for an electronic module, the encapsulation material comprising:

a polymer matrix material; and

electrically-conductive phase change particles dispersed in the matrix material, the phase change particles being encapsulated by a dielectric coating so as to be electrically insulated from each other;

wherein the matrix material is formed of a silicone gel and the phase change particles are formed of a solder alloy.

3. The encapsulation material according to claim 2, wherein the solder alloy comprises indium, tin, bismuth, lead, zinc, cadmium, copper, silver and/or gold.

8. The encapsulation material according to claim 2, wherein the dielectric coating is a polymer capable of containing the phase change particles when molten.

9. An encapsulation material for an electronic module, the encapsulation material comprising:

a polymer matrix material; and

electrically-conductive phase change particles dispersed in the matrix material, the phase change particles being encapsulated by a dielectric coating so as to be electrically insulated from each other;

wherein the dielectric coating comprises dielectric particles dispersed in a dielectric matrix.

10. The encapsulation material according to claim 9, wherein the dielectric particles are formed of a ceramic material having a higher coefficient of thermal conductivity than the matrix material.

13. An encapsulation material contacting an electronic assembly, the encapsulation material comprising:

about 50 to about 80 weight percent of electrically-conductive phase change particles comprising a solder alloy encapsulated by a dielectric polymer coating so as to be electrically insulated from each other, the dielectric polymer coating being capable of containing the phase change particles when molten;

about 0.5 to about 10 weight percent of dielectric particles; and

the balance essentially a silicone gel in which the electrically-conductive phase change particles and the dielectric particles are dispersed, the dielectric particles having a higher coefficient of thermal conductivity than the silicone gel.

14. The encapsulation material according to claim 13, wherein the dielectric particles are formed of alumina, boron nitride, aluminum nitride, silicon carbide and/or silicon nitride.

15. The encapsulation material (30) according to claim 13, wherein the dielectric polymer coating contains about 50 to about 90 weight percent of second dielectric particles dispersed in a polymer matrix, the second dielectric particles having a higher coefficient of thermal conductivity than the silicone gel.

16. The encapsulation material according to claim 15, wherein the second dielectric particles are formed of alumina, boron nitride, aluminum nitride, silicon carbide and/or silicon nitride.

17. The encapsulation material according to claim 15, wherein the second dielectric particles are smaller than the dielectric particles dispersed in the silicone gel.

18. The encapsulation material according to claim 13, wherein the encapsulation material surrounds and contacts a heat-generating electronic device.

19. The encapsulation material according to claim 13, wherein the encapsulation material contacts a heat sink of a heat-generating electronic device.

20. The encapsulation material according to claim 13, wherein the solder alloy is at least one alloy selected from the group consisting of 52In/48Sn, 75In/25Sn, 46.1Bi/34.2Sn/19.3Pb, 55.5Bi/45.5Pb, 56Bi/40Sn/4Zn, 58Bi/42Sn, 60Bi/40Cd, In, 70Sn/18Pb/12In and 63Sn/37Pb.