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Metallized Elastomeric Bumps for Chip and Zero Insertion Force Connectors

IP.com Disclosure Number: IPCOM000113734D
Original Publication Date: 1994-Sep-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Goubau, WM: AUTHOR [+2]

Abstract

Metallized elastomeric bumps are provided for use in Zero Insertion Force (ZIF) connectors or for achieving chip attachment solely with pressure contacts. The bumps are formed from thickened silicon-based elastomers having good adhesion to substrates and are metallized by sputtered copper. The bumps are in contrast to the gold bumps of the prior art which require an average electrical contact force of approximately seventy times greater than the provided metallized elastomeric bumps.

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Metallized Elastomeric Bumps for Chip and Zero Insertion Force Connectors

      Metallized elastomeric bumps are provided for use in Zero
Insertion Force (ZIF) connectors or for achieving chip attachment
solely with pressure contacts.  The bumps are formed from thickened
silicon-based elastomers having good adhesion to substrates and are
metallized by sputtered copper.   The bumps are in contrast to the
gold bumps of the prior art which require an average electrical
contact force of approximately seventy times greater than the
provided metallized elastomeric bumps.

      The starting ingredients of the metallized elastomeric bumps
include a silicon-based elastomer, a thickener, and a metal.  The
silicon-based elastomer is thickened with the thickener to form a
past of adjustable viscosity having good adhesion to a variety of
commonly-used substrates.  The elastomeric paste is screened through
a mask to form an array of raised bumps on a substrate with the
desired height and radius.  Depending on the chosen elastomer and
thickener, the paste typically can be made elastomeric with
negligible weight loss and reflow by thermal cross-linking at
temperatures in the range of 300 to 400 degrees Centigrade.  The
so-formed bumped substrate is then metallized, preferable with
sputtered copper, according to well-known techniques.  If desired,
the metallized bumps and substrate can be photolithographically
patterned and subtractively etched to provide a wiring on the
su...