Cooling apparatus, cooled electronic module, and methods of fabrication thereof employing thermally conductive, wire-bonded pin fins

• US 7,301,770 B2
• Filed: 12/10/2004
• Issued: 11/27/2007
• Est. Priority Date: 12/10/2004
• Status: Expired due to Fees

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Simons, Robert E., Singh, Prabjit, Ellsworth, Michael J. Jr., Campbell, Levi A., Chu, Richard C., Iyengar, Madhusudan K., Schmidt, Roger R.
• Primary Examiner(s): CHERVINSKY, BORIS LEO
• Application Number:
  US11/009,935
• Publication Number:
  US 20060126308A1
• Time in Patent Office: 1,082 Days
• Field of Search: None
• US Class Current: 361/699
• CPC Class Codes: F28F 3/022 the means being wires or pins
• CPC Class Codes: H01L 2224/78301 Capillary
• CPC Class Codes: H01L 23/3677 Wire-like or pin-like cooling fins or heat sinks
• CPC Class Codes: H01L 23/433 Auxiliary members in containers characterised by their shape, e.g. pistons
• CPC Class Codes: H01L 23/473 by flowing liquids H01L23/4332, H01L23/4338 take precedence
• 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 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/19107 off-chip wires

Abstract

A cooling apparatus and method of fabrication are provided for facilitating removal of heat from a heat generating electronic device. The cooling apparatus includes a thermally conductive base having a substantially planar main surface, and a plurality of thermally conductive pin fins wire-bonded to the main surface of the thermally conductive base and disposed to facilitate the transfer of heat from the thermally conductive base. The thermally conductive base can be a portion of the electronic device to be cooled or a separate structure coupled to the electronic device to be cooled. If a separate structure, the thermally conductive base has a coefficient of thermal expansion within a defined range of a coefficient of thermal expansion of the electronic device. In one implementation, the wire-bonded pin fins are discrete, looped pin fins separately wire-bonded to the main surface and spaced less than 300 micrometers apart in an array.

Claims

1. A cooling apparatus comprising:

a thermally conductive base having a main surface;

a plurality of thermally conductive pin fins wire-bonded to the main surface of the thermally conductive base, wherein each pin fin of the plurality of thermally conductive pin fins is bonded to the main surface of the thermally conductive base via a metallurgical diffusion bond of the pin fin to the main surface of the thermally conductive base, the plurality of thermally conductive pin fins being disposed to facilitate transfer of heat from the thermally conductive base; and

wherein the plurality of thermally conductive pin fins comprise a plurality of discrete, looped pin fins, each discrete, looped pin fin comprising a first end and a second end, and being separately wire-bonded at its first end and its second end to the main surface of the thermally conductive base employing a first metallurgical diffusion bond at its first end and a second metallurgical diffusion bond at its second end.

2. The cooling apparatus of claim 1, wherein the main surface of the thermally conductive base is a flat, planar surface and the plurality of thermally conductive pin fins are each thermally merged with the main surface of the thermally conductive base via the metallurgical diffusion bond thereof to the flat, planar main surface of the thermally conductive base.

3. The cooling apparatus of claim 1, wherein the thermally conductive base is a back surface of an electronic device to be cooled, the electronic device being at least one of an integrated circuit chip or multiple integrated circuit chips fabricated of a semiconductor material.

5. The cooling apparatus of claim 1, further comprising a housing sealably engaging the main surface of the thermally conductive base, the housing defining a liquid coolant flow path within which the plurality of thermally conductive pin fins extend, wherein heat is transferred in part from the thermally conductive base through the plurality of thermally conductive pin fins to liquid coolant within the liquid coolant flow path when the cooling apparatus is employed to cool an electronic device coupled to the thermally conductive base.

6. The cooling apparatus of claim 1, wherein the cooling apparatus is a micro-scaled cooling structure, and wherein at least some of the thermally conductive pin fins of the plurality of thermally conductive pin fins are spaced less than 300 micrometers apart in a planar array across the main surface of the thermally conductive base.

4. The cooling apparatus of claim I, wherein the thermally conductive base comprises a non-metallic structure and has a coefficient of thermal expansion within a defined range of a coefficient of thermal expansion of an electronic device to be cooled by the cooling apparatus, the defined range being ±

1.5×

10<sup>−

6</sup>1/K.

7. A cooled electronic module comprising:

a substrate and at least one heat generating electronic device attached thereto; and

a cooling apparatus for cooling the at least one heat generating electronic device, the cooling apparatus comprising;

a plurality of thermally conductive pin fins wire-bonded to one of a surface of the at least one heat generating electronic device or a thermally conductive base coupled to a surface of the at least one heat generating electronic device, wherein each pin fin of the plurality of thermally conductive pin fins is bonded to the one of the surface of the at least one heat generating electronic device or the thermally conductive base coupled thereto via a metallurgical diffusion bond of the pin fin thereto, and wherein the plurality of thermally conductive pin fins are disposed to facilitate transfer of heat from the at least one heat generating electronic device; and

wherein the plurality of thermally conductive pin fins comprise a plurality of discrete, looped pin fins, each discrete, looped pin fin comprising a first end and a second end, and being separately wire-bonded at its first end and its second end to the one of the surface of the at least one heat generating electronic device or the thermally conductive base coupled to the surface of the at least one heat generating electronic device employing a first metallurgical diffusion bond at its first end and a second metallurgical diffusion bond at its second end.

8. The cooled electronic module of claim 7, wherein the one of the surface of the at least one heat generating electronic device or the thermally conductive base coupled to the surface of the at least one heat generating electronic device comprises a flat, planar surface, and wherein the wire-bonded pin fins of the plurality of thermally conductive pin fins are each thermally merged with the flat, planar surface.

9. The cooled electronic module of claim 7, wherein the plurality of thermally conductive pin fins are wire-bonded to the thermally conductive base, which is coupled to the surface of the at least one heat generating electronic device, and wherein the thermally conductive base comprises a non-metallic structure and has a coefficient of thermal expansion within a defined range of a coefficient of thermal expansion of the at least one heat generating electronic device, the defined range being ±

1.5 ×

10<sup>−

6</sup> 1/K.

10. The cooled electronic module of claim 9, wherein the at least one heat generating electronic device comprises silicon, and wherein the thermally conductive base comprises at least one of silicon carbide, silicon, aluminum nitride, diamond, and a copper-molybdenum-copper composite, and wherein the plurality of thermally conductive pin fins comprise copper.

11. The cooled electronic module of claim 7, wherein the cooling apparatus is a micro-scaled cooling structure, and wherein at least some thermally conductive pin fins of the plurality of thermally conductive pin fins are spaced less than 300 micrometers apart in a planar array.

12. The cooled electronic module of claim 7, further comprising a housing sealably coupled to the substrate, the housing defining a liquid coolant flow path within which the plurality of thermally conductive pin fins extend, wherein heat is transferred from the at least one heat generating electronic device through the plurality of thermally conductive pin fins to liquid coolant within the liquid coolant flow path, and wherein at least some pin fins of the plurality of thermally conductive pin fins are soldered intermediate their first and second ends to a coolant inlet manifold structure.

13. The cooled electronic module of claim 7, further comprising:

a housing sealably coupled to the substrate, the housing defining a liquid coolant flow path within which the plurality of thermally conductive pin fins extend;

wherein the housing comprises a coolant inlet manifold with at least one orifice disposed over the one surface to which the plurality of thermally conductive pin fins are bonded, the at least one orifice for injecting coolant onto the at least one surface, wherein heat is transferred from the at least one heat generating electronic device through the plurality of thermally conductive pin fins to the injected coolant, and at least some pin fins of the plurality of conductive pin fins are soldered intermediate their first and second ends to the coolant inlet manifold; and

wherein the housing further comprises a coolant outlet manifold for removal of coolant after contacting the one surface and the plurality of thermally conductive pin fins, the coolant outlet manifold being disposed at the periphery of the at least one heat generating electronic device.

14. The cooled electronic module of claim 13, wherein the plurality of thermally conductive pin fins are bonded directly to the surface of the at least one heat generating electronic device, and wherein the surface of the at least one heat generating electronic device is a back surface of an electronic device to be cooled, the electronic device being at least one of an integrated circuit chip or multiple integrated circuit chips fabricated of a semiconductor material, wherein the back surface of the electronic device is a flat, planar surface and the plurality of thermally conductive pin fins are each thermally merged with the back surface of the electronic device by a metallurgical diffusion bond thereon and wherein the cooling apparatus is a micro-scaled cooling structure, and at least some of the thermally conductive pin fins of the plurality of thermally conductive pin fins are spaced less than 300 micrometers apart in a planar array across the back surface of the electronic device.

15. A method of fabricating a cooling apparatus comprising:

providing a thermally conductive base having a main surface;

wire-bonding a plurality of thermally conductive pin fins to the main surface of the thermally conductive base, wherein each pin fin of the plurality of thermally conductive pin fins is bonded to the main surface of the thermally conductive base via a metallurgical diffusion bond of the pin fin to the main surface of the thermally conductive base, and wherein the plurality of thermally conductive pin fins are disposed across the main surface to facilitate transfer of heat from the thermally conductive base; and

wherein the plurality of thermally conductive pin fins comprise a plurality of discrete, looped pin fins, each discrete, looped pin fin comprising a first end and a second end, and being separately wire-bonded at its first end and its second end to the main surface of the thermally conductive base employing a first metallurgical diffusion bond at its first end and a second metallurgical diffusion bond at its second end.

16. The method of claim 15, wherein the main surface of the thermally conductive base is planar and the wire-bonding comprises for each thermally conductive pin fin, thermally merging the thermally conductive pin fin to the planar main surface of the thermally conductive base via the metallurgical diffusion bond thereof to the planar main surface of the thermally conductive base.

17. The method of claim 15, wherein the wire-bonding comprises for each thermally conductive pin fin forming the discrete, looped pin fin thermally merged with the thermally conductive base, and wherein at least some thermally conductive pin fins of the plurality of thermally conductive pin fins are spaced less than 300 micrometers apart in a planar array across the main surface of the thermally conductive base.

18. The method of claim 15, wherein the thermally conductive base is a back surface of an electronic device to be cooled, the electronic device being at least one of an integrated circuit chip or multiple integrated circuit chips fabricated of a semiconductor material.

19. The method of claim 15, wherein the thermally conductive base comprises a non-metallic structure and has a coefficient of thermal expansion within a defined range of a coefficient of thermal expansion of an electronic device to be cooled by the cooling apparatus, the defined range being ±

1.5×

10<sup>−

6</sup>1/K.

20. The method of claim 15, further comprising providing a housing sealably engaged to the main surface of the thermally conductive base, the housing defining a liquid coolant flow path within which the plurality of thermally conductive pin fins extend, wherein heat from an electronic device to be cooled is transferred in part from the thermally conductive base through the plurality of thermally conductive pin fins to liquid coolant within the liquid coolant flow path when the electronic device is coupled to the thermally conductive base.