Browse Prior Art Database

LSI Cooling and Packaging Design

IP.com Disclosure Number: IPCOM000111040D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Niu, TM: AUTHOR [+2]

Abstract

This disclosure proposes that a thin flexible metal interface be used to remove heat from a C4 mounted silicon chip to provide necessary cooling. The configuration of the interface is detailed in Fig. 1b. A sheet of copper is formed into rails approximately 80 mils high. Copper plates are soldered to the top and bottom of the rails. The side walls of the rails are then deformed to provide a flexible action as shown in Fig. 1b. The top copper plate is then cut into squares of approximately 60 mils. The depth of the cut is extended to half the height of the rails. Each square in the top plate can now be deformed independently. The thermal interface is designed to flex approximately 15% of its total thickness under low loads to compensate for chip height variations and non-planar surfaces.

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LSI Cooling and Packaging Design

      This disclosure proposes that a thin flexible metal interface
be used to remove heat from a C4 mounted silicon chip to provide
necessary cooling.  The configuration of the interface is detailed in
Fig. 1b.  A sheet of copper is formed into rails approximately 80
mils high.  Copper plates are soldered to the top and bottom of the
rails.  The side walls of the rails are then deformed to provide a
flexible action as shown in Fig. 1b.  The top copper plate is then
cut into squares of approximately 60 mils.  The depth of the cut is
extended to half the height of the rails.  Each square in the top
plate can now be deformed independently.  The thermal interface is
designed to flex approximately 15% of its total thickness under low
loads to compensate for chip height variations and non-planar
surfaces.

      This type of continuous interface can be used for thermal
enhancement of single or multichip carriers.  An advantage of this
interface over a Radial Finger Contact (RFC) is that it can be used
with closely spaced chips and chips located near the edges of an
assembly.  Also this assembly will accommodate components, such as
capacitors, that are placed close to a chip whose height is greater
than that of the chip.  This interface design is tested using a
single CEFET chip 36mm MC module.  The Rint of the assembly is
measured as 4.2C/watt alone and 3.2C/watt with thermal grease added.
By comparison a RFC in the same assem...