Browse Prior Art Database

Liquid Piston with Phase Change to Absorb Thermal Transients

IP.com Disclosure Number: IPCOM000116570D
Original Publication Date: 1995-Oct-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 77K

Publishing Venue

IBM

Related People

Chrysler, GM: AUTHOR [+2]

Abstract

A method of controlling, or at least reducing, the temperature fluctuation of CMOS chips caused by the power fluctuation inherent in CMOS circuitry is disclosed. A phase-change material chosen for its melting temperature is placed in close contact with the CMOS chips in a SCM or MCM package.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 61% of the total text.

Liquid Piston with Phase Change to Absorb Thermal Transients

      A method of controlling, or at least reducing, the temperature
fluctuation of CMOS chips caused by the power fluctuation inherent in
CMOS circuitry is disclosed.  A phase-change material chosen for its
melting temperature is placed in close contact with the CMOS chips in
a SCM or MCM package.

      This invention discloses a method of controlling or reducing
the temperature fluctuations, and therefore the thermally induced
stresses in the C4 balls, of CMOS chips undergoing power
fluctuations.  The idea is to provide a very large thermal capacity
that is thermally in close proximity to the chip surface (therefore
very close to the C4s).  The concept is presented in Figs. 1 and 2.
The simplest design is presented in Fig. 1.  A multi-chip substrate
(1) is populated with CMOS chips (2).  The substrate and chips are
enclosed within a metal housing (3).  The housing has provisions for
attaching a heat sink (4) so that the power dissipated by the chips
can be easily transferred to a cooling air stream.  A thermal grease
(or oil) layer (5) between the chips and the piston provides a low
resistance thermal path.  Within the module the normal solid (copper
or aluminum) pistons are replaced by hollowed, spring-loaded pistons
(6) filled with an appropriate material (7) which can undergo a
solid-liquid phase change.  The gap (8) at the top of the piston is
filled with a gas - a compressible media to all...