Browse Prior Art Database

Multiple Heatsink Thermal Solution

IP.com Disclosure Number: IPCOM000118654D
Original Publication Date: 1997-May-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Alcoe, DJ: AUTHOR [+2]

Abstract

Disclosed is the use of more than one heatsink on an electronic component to mitigate some of the following problems. Thermal management of high-power chips often requires the use of large, stiff heatsinks adhesively bonded to a chip package. For some chip packages like tape ball grid array, there exists a mismatch in the thermal expansion due to both material expansion coefficient differences and thermal gradients. This expansion mismatch, coupled with the mechanical stiffness of the heatsink, may lead to a reduction in thermo-mechanical fatigue life when a heatsink is used. If direct attachment of the heatsink to the chip is required, the expansion mismatch is even greater and may lead to chip fracture.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Multiple Heatsink Thermal Solution

      Disclosed is the use of more than one heatsink on an electronic
component to mitigate some of the following problems.  Thermal
management of high-power chips often requires the use of large, stiff
heatsinks adhesively bonded to a chip package.  For some chip
packages like tape  ball grid array, there exists a mismatch in the
thermal expansion due to both material expansion coefficient
differences and thermal gradients.  This expansion mismatch, coupled
with the mechanical stiffness of the heatsink, may lead to a
reduction in thermo-mechanical  fatigue life when a heatsink is used.
If direct attachment of the heatsink to the chip is required, the
expansion mismatch is even greater  and may lead to chip fracture.

      Instead of bonding one large heatsink to the chip package (or
chip), several smaller heatsinks are bonded to the chip package in an
array fashion, using known bonding procedures and known heatsinks.

      This has the mechanically beneficial effect of reducing the
effective distance from central neutral point by a large fraction,
thereby reducing the overall strain mismatch substantially.  For
example, if four equally sized square-based heatsinks were attached
to a square package instead of one large square heatsink with the
same total base coverage, the strain mismatch would be cut in half
for each heatsink.  This would have the effect of reducing the
overall bending of the package, changing the distribution of bending
to a more  even pattern, and reducing/redistributing the effective
stiffness of the  heatsinks on the package.  Similarly, an array of
nine heatsinks could  have one-third the strain mismatch of one large
heatsink.

      This substantial reduction of adhesive strain would...