Thermal interface materials and methods for their preparation and use

• US 6,791,839 B2
• Filed: 06/25/2002
• Issued: 09/14/2004
• Est. Priority Date: 06/25/2002
• Status: Expired due to Term

• Current Assignee: Dow Silicones Corporation (Dow, Inc.)
• Original Assignee: Dow Corning Corporation (Dow, Inc.)
• Inventors: Bhagwagar, Dorab Edul
• Primary Examiner(s): Tucker, Philip
• Assistant Examiner(s): Feely, Michael J
• Application Number:
  US10/183,789
• Publication Number:
  US 20030234074A1
• Time in Patent Office: 812 Days
• Field of Search: 428/413, 428/414, 428/416, 428/418, 428/423.1, 428/447, 428/448, 428/450, 428/473.5, 428/474.4, 428/480, 428/458, 428/460, 428/461, 428/463, 428/500, 428/523, 428/332, 428/339, 523/400, 523/440, 523/457, 523/459, 523/460, 524/80, 524/401, 524/403, 524/408, 524/413, 524/858, 524/859, 524/860, 524/861, 524/862, 524/866, 361/704, 361/705, 361/707, 361/708, 361/709, 257/717, 156/327, 156/329, 156/330, 156/330.9, 156/331.1
• US Class Current: 361/705
• CPC Class Codes: C08L 83/00 Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
• CPC Class Codes: C09J 2483/00 Presence of polysiloxane
• CPC Class Codes: C09J 5/06 involving heating of the applied adhesive
• CPC Class Codes: C09J 9/02 Electrically-conducting adhesives
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/29109 Indium [In] as principal constituent
• CPC Class Codes: H01L 2224/29111 Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/2919 with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
• 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 2224/29309 Indium [In] as principal constituent
• CPC Class Codes: H01L 2224/29311 Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/73204 the bump connector being embedded into the layer connector
• CPC Class Codes: H01L 2224/73253 Bump and layer connectors
• CPC Class Codes: H01L 23/3675 characterised by the shape of the housing
• CPC Class Codes: H01L 23/3737 Organic materials with or without a thermoconductive filler
• CPC Class Codes: H01L 23/433 Auxiliary members in containers characterised by their shape, e.g. pistons
• CPC Class Codes: H01L 24/28 Structure, shape, material or disposition of the layer connectors prior to the connecting process
• 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 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01004 : Beryllium [Be]
• CPC Class Codes: H01L 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01012 : Magnesium [Mg]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01015 : Phosphorus [P]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/0102 : Calcium [Ca]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01027 : Cobalt [Co]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/0103 : Zinc [Zn]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01039 : Yttrium [Y]
• CPC Class Codes: H01L 2924/0104 : Zirconium [Zr]
• CPC Class Codes: H01L 2924/01041 : Niobium [Nb]
• CPC Class Codes: H01L 2924/01045 : Rhodium [Rh]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01049 : Indium [In]
• CPC Class Codes: H01L 2924/0105 : Tin [Sn]
• CPC Class Codes: H01L 2924/01051 : Antimony [Sb]
• CPC Class Codes: H01L 2924/01056 : Barium [Ba]
• CPC Class Codes: H01L 2924/01057 : Lanthanum [La]
• CPC Class Codes: H01L 2924/01061 : Promethium [Pm]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01083 : Bismuth [Bi]
• CPC Class Codes: H01L 2924/0132 : Binary Alloys
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/0133 : Ternary Alloys
• CPC Class Codes: H01L 2924/0134 : Quaternary Alloys
• CPC Class Codes: H01L 2924/0665 : Epoxy resin
• CPC Class Codes: H01L 2924/12042 : LASER
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/15311 : being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/16152 : Cap comprising a cavity for hosting the device, e.g. U-shaped cap
• CPC Class Codes: H01L 2924/3011 : Impedance
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding
• CPC Class Codes: Y10T 428/26 : Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/269 : including synthetic resin or polymer layer or component

Abstract

A composition that can be used to prepare a thermal interface material includes: A) a curable matrix having a curing temperature, B) a metal filler having a low melting point, optionally C) a spacer, and optionally D) a conductive filler. The temperature at which component B) commences softening is less than the curing temperature of component A). A thermal interface material is prepared by: 1) interposing the composition between an electronic component and a heat spreader to form a bondline, 2) heating the composition to a temperature higher than the temperature at which component B) commences softening but less than the curing temperature of component A) and optionally applying pressure to the composition, and 3) heating the composition to a temperature greater than or equal to the curing temperature of component A). The average particle size of component B) is greater than or equal to the bondline thickness.

Claims

1. A composition comprising:

A) a curable matrix having a curing temperature,

B) a low melting metal filler having a softening temperature,

C) a spacer, and

with the provisos that

i) the softening temperature of component B) is less than the curing temperature of component A), and

ii) the average particle size of component B) is greater than the average particle size of component C).

2. The composition of claim 1, where component A) comprises a polysiloxane, an epoxy, a phenolic, a novolac resin, a polyacrylate, a polyurethane, a polyimide, a polyester, a maleimide resin, a cyanate ester, a polyimide, a polyurea, a cyanoacrylate, or a combination thereof.

3. The composition of claim 1, where component A) comprises a polysiloxane comprising an addition reaction curable matrix, a condensation reaction curable matrix, a peroxide reaction curable matrix, or a combination thereof.

4. The composition of claim 1, where component A) comprises:

I) a curable silicone base polymer,

II) a curing agent for component I),

III) a catalyst, and

optionally IV) a catalyst inhibitor.

5. The composition of claim 4, where

a) component I) comprises an alkenyl-functional polyorganosiloxane,

b) component II) comprises an organohydrogenpolysiloxane,

c) component III) comprises a hydrosilylation catalyst, and

d) component IV) comprises a hydrosilylation reaction catalyst inhibitor.

6. The composition of claim 1, where

a) component B) has a melting temperature of at least 50°

C., and

b) component B) has a melting temperature of up to 250°

C.

7. The composition of claim 1, where component B) comprises a non-eutectic alloy.

8. The composition of claim 1, where component B) comprises Bi, In, Sn, or an alloy thereof.

9. The composition of claim 8, where component B) further comprises Ag, Au, Cd, Cu, Pb, Sb, Zn, or a combination thereof.

10. The composition of claim 1, further comprising:

D) a conductive filler,

E) a treating agent for component D),

F) an adhesion promoter,

G) a vehicle,

H) a surfactant,

I) a flux agent,

J) an acid acceptor, or

a combination thereof.

11. A device comprising:

a) an electronic component,

b) an interface material, and

c) a heat sink;

where the interface material is arranged along a thermal path extending from a surface of the electronic component to a surface of the heat sink, and where the interface material comprises a cured product of the composition of claim 1.

12. A device comprising:

a) a heat spreader, and

b) an interface material on a surface of the heat spreader,

where the interface material and the heat spreader are configured to comprise a portion of a thermally conductive path between an electronic component and a heat sink, and where the interface material comprises a cured product of the composition of claim 1.

13. A method comprising:

1) interposing a composition between a first substrate and a second substrate to form a bondline having a bondline thickness, where the composition comprises

A) a curable matrix having a curing temperature, and

B) a low melting metal filler having a softening temperature,

with the provisos that

i) the softening temperature of component B) is less than the curing temperature of component A), and

ii) the average particle size of component B) is greater than or equal to the bondline thickness;

2) heating the composition to a temperature less than the curing temperature of component A) and greater than or equal to the softening temperature of component B); and

thereafter

3) heating the composition to a temperature greater than or equal to the curing temperature of component A).

14. The method of claim 13, where the composition further comprises:

C) a spacer,

D) a conductive filler,

E) a treating agent for component D),

F) an adhesion promoter,

G) a vehicle,

H) a surfactant,

I) a flux agent,

J) an acid acceptor, or

a combination thereof.

15. The method of claim 13, where

I) the heat source comprises an electronic device, and

II) the heat spreader comprises a heat sink, a thermally conductive plate, a thermally conductive cover, a fan, or a circulating coolant system.

16. The method of claim 13, further comprising:

applying pressure to the composition after step

     1) and before or during step

     2).

17. The method of claim 13, where

a) the first substrate comprises a heat source, and

b) the second substrate comprises a heat spreader.