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Internal Thermal Design of LSI Package

IP.com Disclosure Number: IPCOM000088282D
Original Publication Date: 1977-May-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Chu, RC: AUTHOR

Abstract

A typical LSI (large scale integrated) package has a primary thermal bottleneck right at the interface between the chip 10 and the substrate 12. This results from the small area and the other electric interconnection requirements which severely limit the cross-sectional area for thermal conduction. The substrate 12 area which is immediately adjacent to the chip presents a secondary thermal bottleneck. The internal thermal flow path of a LSI package can be improved by providing a thick (20 to 30 mils or more), but soft, metal foil 14, e.g., aluminum and indium, so designed that it serves as a parallel path for thermal conduction.

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Internal Thermal Design of LSI Package

A typical LSI (large scale integrated) package has a primary thermal bottleneck right at the interface between the chip 10 and the substrate 12. This results from the small area and the other electric interconnection requirements which severely limit the cross-sectional area for thermal conduction. The substrate 12 area which is immediately adjacent to the chip presents a secondary thermal bottleneck. The internal thermal flow path of a LSI package can be improved by providing a thick (20 to 30 mils or more), but soft, metal foil 14, e.g., aluminum and indium, so designed that it serves as a parallel path for thermal conduction.

Referring to Fig. 1, the chip 10 to be cooled is shown attached to a substrate 12, which in turn contains pins 11 for plugging to a board or the like. Generally, the thermal path is from the chip through the connecting means to the substrate and subsequently to the cooling air. The fixed but soft metal foil 14 is laid directly over the chip 10 in good thermal contact therewith and is long enough to attach to the substrate, providing a parallel thermal path to the substrate 12 and, thereby, improving heat dissipation.

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