Thermal paste preforms as a heat transfer media between a chip and a heat sink and method thereof

• US 6,275,381 B1
• Filed: 12/10/1998
• Issued: 08/14/2001
• Est. Priority Date: 12/10/1998
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Pompeo, Frank L., Edwards, David L., Iruvanti, Sushumna, Daves, Glenn G., Farooq, Shaji
• Primary Examiner(s): Picard, Leo P.
• Assistant Examiner(s): CHERVINSKY, BORIS LEO
• Application Number:
  US09/208,790
• Publication Number:
  US 20010021102A1
• Time in Patent Office: 978 Days
• Field of Search: 361/702, 361/704, 361/705, 361/706, 361/707, 361/713, 361/722, 361/717-719, 165/80.3, 165/185, 174/16.3, 174/252, 174/52.4, 257/706, 257/707, 257/712, 257/713, 257/722, 257/730, 257/731
• US Class Current: 361/717
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/73253 Bump and layer connectors
• CPC Class Codes: H01L 23/42 Fillings or auxiliary members in containers or encapsulations selected or arranged to facilitate heating or cooling
• CPC Class Codes: H01L 2924/16152 Cap comprising a cavity for hosting the device, e.g. U-shaped cap
• CPC Class Codes: H05K 7/20454 with a conformable or flexible structure compensating for irregularities, e.g. cushion bags, thermal paste

Abstract

The present invention relates generally to a new apparatus and method for introducing thermal paste into semiconductor packages. More particularly, the invention encompasses an apparatus and a method that uses at least one preform of thermal paste for the cooling of at least one chip in a sealed semiconductor package. The thermal paste preform is subcooled, and is transferred onto a module component from a separable transfer sheet, or is placed onto the module component using an attached and/or imbedded mesh. The preform of thermal paste may be of simple or complex shape, and enables cooling of one or more chips in a module.

Claims

1. A thermal paste preform for assembly in a semiconductor package having a heat generating device and a heat dissipation device with a gap therebetween, the thermal paste preform comprising a slug of thermal paste material, said slug having a shape so as to substantially cover said heat generating device upon assembly in the semiconductor package, said slug having a slug thickness not less than the gap between the heat generating device and the heat dissipation device, said slug having a temperature and having stiffness and tackiness properties in accordance with the temperature thereof, so that the stiffness and tackiness properties of the slug facilitate shipping and storing of said thermal paste preform.

2. The thermal paste preform of claim 1, wherein said slug is attached to a transfer sheet and wherein said transfer sheet is detachable from said slug, so that said transfer sheet facilitates assembly of said slug in a semiconductor package.

3. The thermal paste preform of claim 1, wherein said slug further comprises a mesh imbedded therein, said mesh having a mesh thickness substantially smaller than said slug thickness.

4. The thermal paste preform of claim 3 wherein said mesh is of a conductive material.

5. The thermal paste preform of claim 3, wherein said mesh is of a non-conductive material.

6. The thermal paste preform of claim 1, wherein said slug is attached to a transfer sheet, said transfer sheet is detachable from said slug, and said slug further comprises a mesh imbedded therein, said mesh having a mesh thickness substantially smaller than said slug thickness.

7. A semiconductor package comprising:

a heat source;

a slug formed of thermal paste, said slug having an assembled slug thickness;

a mesh imbedded within said slug, said mesh having a mesh thickness substantially smaller than said assembled slug thickness; and

a thermal dissipation device,

assembled so that said slug is sandwiched between and in thermal contact with said heat source and said thermal dissipation device, and so that said mesh imbedded within said slug impedes the flow of said thermal paste.

8. The semiconductor package of claim 7, wherein said mesh is of a conductive material.

9. The semiconductor package of claim 7, wherein said mesh is of a non-conductive material.

10. The semiconductor package of claim 7, wherein said heat source is a semiconductor chip.

11. The semiconductor package of claim 7, wherein said thermal dissipation device is a thermal cap.

12. The semiconductor package of claim 7, wherein said thermal dissipation device is a heat.