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Preformed Polyimide Membrane

IP.com Disclosure Number: IPCOM000089697D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Gazdik, CE: AUTHOR

Abstract

A thermal enhancement technique for an integrated circuit chip mounted on a carrier and enclosed by a cap includes an enclosed amount of thermal grease mounted to the underside of the cap by a very thin film of polyimide having a preformed bubble shape therein to accommodate the grease. This preformed film must be extremely thin to meet the necessary heat transfer requirements to provide the improved thermal enhancement.

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Preformed Polyimide Membrane

A thermal enhancement technique for an integrated circuit chip mounted on a carrier and enclosed by a cap includes an enclosed amount of thermal grease mounted to the underside of the cap by a very thin film of polyimide having a preformed bubble shape therein to accommodate the grease. This preformed film must be extremely thin to meet the necessary heat transfer requirements to provide the improved thermal enhancement.

The means for forming such a bubble shape in a polyimide film consists of placing a flat sheet of uncured polyimide film 3 of the desired thickness over a lower mold portion 4. The dotted line indicates the initial position of the uncured polyimide film. The mold cover 1 is positioned over the film, thereby forming the chamber 5. Next, the flat polyimide film is pressurized with an inert gas, such as nitrogen, through port 2, and the fixture is heated to cure the polyimide (for example, to about 320 degrees C). Due to the pressure from the inert gas, the polyimide film will be deflected to form a bubble 6 therein, and when the cure of the film has been completed, this bubble will be permanently formed in the film. Using this technique, it is possible to provide the desired films in thickness as low as 0.2 mils.

It is readily apparent that this technique lends itself to producing multiple films using a plurality of mold segments similar to that shown in the figure.

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