Browse Prior Art Database

Flexible Circuit Interconnect for Cryogenic Applications

IP.com Disclosure Number: IPCOM000104291D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 1 page(s) / 33K

Publishing Venue

IBM

Related People

Lanzetta, AP: AUTHOR [+5]

Abstract

It is well known that the operation of certain semiconductor circuits at cryogenic temperatures offer substantial performance advantages when compared to room temperature operation. It is also well known that the differing expansion rates of the various materials used in packaging such semiconductors can lead to damage when the temperature of packaged semiconductor elements is cycled repeatedly from room temperature to cryogenic temperature.

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This is the abbreviated version, containing approximately 97% of the total text.

Flexible Circuit Interconnect for Cryogenic Applications

      It is well known that the operation of certain semiconductor
circuits at cryogenic temperatures offer substantial performance
advantages when compared to room temperature operation.  It is also
well known that the differing expansion rates of the various
materials used in packaging such semiconductors can lead to damage
when the temperature of packaged semiconductor elements is cycled
repeatedly from room temperature to cryogenic temperature.

      Described is an integrated system to limit thermally induced
strain damage of a lead frame attached to a device carrier made from
a material of different expansion rate.  Specific to this disclosure,
the lead frame is made from copper connectors that are enclosed by
polyimide dielectric and affixed with a suitable glue.  The lead
frame is interconnected to a multichip module, made of silicon,
ceramic, glass ceramic, or other suitable material.  To limit the
difference in the Coefficients of Thermal Expansion (CTE) between the
leadframe and mating carrier, a retention device is attached in close
proximity to the carrier that exhibits the same CTE.  The retention
device, or retainer bar, is of sufficient thickness to dominate the
growth of the leadframe once attached.  The bar is attached to the
leadframe with a suitable adhesive.  Other embodiments may include
the use of steel or copper alloy leadframes with polyimide, Teflon
(R) or other organic substr...