Integrated release films for phase-change interfaces

• US 6,399,209 B1
• Filed: 03/28/2000
• Issued: 06/04/2002
• Est. Priority Date: 04/16/1999
• Status: Expired due to Fees

• Current Assignee: Berquist Company The (Henkel AG & Co KGaA)
• Original Assignee: Berquist Company The (Henkel AG & Co KGaA)
• Inventors: Kranz, Robert E., Jewram, Radesh, Misra, Sanjay
• Primary Examiner(s): Moore, Margaret G.
• Assistant Examiner(s): Zimmer, Marc S.
• Application Number:
  US09/536,419
• Time in Patent Office: 798 Days
• Field of Search: 428/620, 428/143, 428/348, 428/352, 428/447, 428/480, 428/484, 428/500, 361/706, 524/588, 524/404, 524/430, 524/437
• US Class Current: 428/447
• CPC Class Codes: B32B 15/08 of synthetic resin
• CPC Class Codes: C09K 5/063 Materials absorbing or liberating heat during crystallisation; Heat storage materials
• 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 428/24372 Particulate matter
• CPC Class Codes: Y10T 428/31663 As siloxane, silicone or silane
• CPC Class Codes: Y10T 428/31786 Of polyester [e.g., alkyd, etc.]
• CPC Class Codes: Y10T 428/31801 Of wax or waxy material
• CPC Class Codes: Y10T 428/31855 Of addition polymer from unsaturated monomers

Abstract

A thermally conductive conformable interface pad for inter-position between a heat generating solid state electronic device and a heat sinking surface. The interface comprises a laminate of at least two layers, including a relatively soft conformable body layer with at least one surface consisting of an integrally bonded anti-blocking layer. The conformable body layer preferably comprises a thermally stable wax consisting of an alkyl substituted poly (hydro, methyl-siloxane) wax and a thermally conductive particulate solid, while the anti-blocking layer may comprise a mixture of an alkyl substituted poly (hydro, methyl-siloxane) wax and a silicone wax, a glassy polyester layer, or a cross-linked acrylic layer.

Claims

1. A thermally conductive conformable interface pad for inter-position along the heat dissipating path between a solid state electronic device and heat sinking surface, and comprising a laminate with a relatively soft conformable body layer having opposed major surfaces and with at least one major surface consisting of an integrally bonded anti-blocking layer, said laminate being characterized in that:

(a) said conformable body layer comprises a blend of microcrystalline wax, an alkyl substituted poly (hydro, methyl-siloxane) wax, and a thermally conductive particulate solid, the particulate solid having a particle size of up to about 10 microns, wherein said microcrystalline wax and said alkyl substituted poly (hydro, methyl-siloxane) wax components, in combination, are present in said blend in the amount of between about 18% and 55% by weight, balance thermally conductive particulate solids; and

(b) said integrally bonded anti-blocking layer being a resinous material selected from the group consisting of a mixture of an alkyl substituted poly (hydro, methyl-siloxane) wax and a microcrystalline wax;

a mixture of a glassy polyester layer with a glass transition temperature of at least about 70°

C.; and

a mixture of a cross-linked acrylic.

5. The interface pad of claim 1 wherein said conformable interface pad further comprising a layer of aluminum foil interposed between said base layer and said anti-blocking layer, wherein the aluminum foil has a thickness ranging from between about 0.5 and 2 mils.

6. The interface pad of claim 1 being particularly characterized in that said microcrystalline wax in said conformable body layer comprises between about 10 and 20 parts per hundred weight of thermally conductive particulate.

7. The interface pad of claim 6 being particularly characterized in that said microcrystalline wax in said conformable body layer comprises 100 parts per 600 parts by weight of thermally conductive particulate.

8. The interface pad of claim 1 being particularly characterized in that the conformable body layer includes a flexibilizer component selected from the group consisting of ethylene vinyl acetate, styrenic thermoplastic elastomers consisting of block copolymers of styrene-ethylene-butylene-styrene and polyvinylbutyral present in an amount of between about 5% and 10% by weight.

2. A thermally conductive conformable interface pad for inter-position along the heat dissipating path between a solid state electronic device and heat sinking surface, and comprising a laminate with a relatively soft conformable body layer having opposed major surfaces and with at least one major surface consisting of an integrally bonded anti-blocking layer, said laminate being characterized in that:

(a) said conformable body layer comprises a blend of a microcrystalline wax, an alkyl substituted poly (hydro, methyl-siloxane) wax, and a thermally conductive particulate solid, the particulate solid having a particle size of up to about 10 microns, wherein said microcrystalline wax and said alkyl substituted poly (hydro, methyl-siloxane) wax components, in combination, are present in said blend in the amount of between about 18 and 55 by weight, balance thermally conductive particulate solids; and

(b) said integrally bonded anti-blocking layer comprises a mixture of an alkyl substituted poly (hydro, methyl-siloxane) wax and a microcrystalline wax with said mixture being blended with a thermally conductive particulate solid, and wherein said microcrystalline wax has a melting point which is about 10°

C. greater than that of said alkyl substituted poly (hydro, methyl-siloxane) wax, and wherein said thermally conductive particulate solid has a size of up to 5 microns and comprises between 75% and 85% of said blend, balance alkyl substituted poly (hydro, methyl-siloxane) wax/microcrystalline wax mixture.

9. The interface pad of claim 2 being particularly characterized in that the conformable body layer contains a plasticizer component selected from the group consisting of short chain polystyrene;

short chain hydrocarbons; and

penta-erythritol esters of wood rosin present in an amount of between about 10% and 15%.

10. The interface pad of claim 2 wherein the integrally bonded anti-block layer consists of a mixture of microcrystalline and alkyl substituted poly (hydro, methyl-siloxane) wax, and wherein the ratio of alkyl substituted poly (hydro, methyl-siloxane) wax to microcrystalline wax is between about 3:

1 and 1;

5, and wherein said integrally bonded anti-block layer has a melting point which is in the range of about 10°

C. greater than the melting point of said conformable body layer.

11. The interface pad of claim 10 wherein the conformable body layer has a melting point of about 55°

C. and said anti-block layer has a melting point of about 65°

C.

3. A thermally conductive conformable interface pad for inter-position along the heat dissipating path between a solid state electronic device and heat sinking surface, and comprising a laminate with a relatively soft conformable body layer having opposed major surfaces and with at least one major surface consisting of an integrally bonded anti-blocking layer, said laminate being characterized in that:

(a) said conformable body layer comprises a microcrystalline wax, an alkyl substituted poly (hydro, methyl-siloxane) wax, and a thermally conductive particulate solid, the particulate solid having a particle size of up to about 10 microns, wherein said wax components, in combination, are present in said blend in the amount of between about 18% and 55% by weight, balance thermally conductive particulate solids; and

(b) said integrally bonded anti-blocking layer comprises a mixture of a glassy polyester layer, preferably with glass transition temperature of 70°

C. or higher and being blended with thermally conductive fillers selected from the group consisting of alumina, boron nitride and graphite in order to impart it a thermal conductivity of 1−

4 W−

m<sup>−

1</sup>−

K<sup>−

1</sup>.

4. A thermally conductive conformable interface pad for inter-position along the heat dissipating path between a solid state electronic device and heat sinking surface, and comprising a laminate with a relatively soft conformable body layer having opposed major surfaces and with at least one major surface consisting of an integrally bonded anti-blocking layer, said laminate being characterized in that:

(a) said conformable body layer comprises a thermally stable wax consisting of a microcrystalline wax, an alkyl substituted poly (hydro, methyl-siloxane) wax, and a thermally conductive particulate solid, the particulate solid having a particle size of up to about 10 microns, wherein said microcrystalline wax and said alkyl substituted poly (hydro, methyl-siloxane) wax components, in combination, are present in said blend in the amount of between about 18% to 55% by weight, balance thermally conductive particulate solids; and

(b) said integrally bonded anti-blocking layer comprises a mixture of a cross-linked acrylic layer blended with thermally conductive fillers selected from the group consisting of alumina, boron nitride and graphite in order to impart it a thermal conductivity of 1−

4 W−

m<sup>−

1</sup>−

K<sup>−

1</sup>.