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Tungsten Probes with Copper Donor Wire

IP.com Disclosure Number: IPCOM000107700D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Vigliotti, DR: AUTHOR [+2]

Abstract

In the repair of an electrically "open" copper circuit using self- induced repair (SIR), one first deposits a thin bridge of palladium between the open ends, which is then copper plated to a thickness of several microns (*). Alternatively, for near opens, the thinned defect region also requires copper plate-up. In both cases, copper sulfate solution is used in conjunction with Joule heating while the circuit is submerged to produce a local shift in rest potential. This shift causes the palladium or the thinned copper region to become cathodic, resulting in copper deposition from the copper ions in solution. At the same time, anodic dissolution must occur to maintain charge conservation via this thermally driven exchange plating or thermobattery effect.

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Tungsten Probes with Copper Donor Wire

       In the repair of an electrically "open" copper circuit
using self- induced repair (SIR), one first deposits a thin bridge of
palladium between the open ends, which is then copper plated to a
thickness of several microns (*). Alternatively, for near opens, the
thinned defect region also requires copper plate-up.  In both cases,
copper sulfate solution is used in conjunction with Joule heating
while the circuit is submerged to produce a local shift in rest
potential.  This shift causes the palladium or the thinned copper
region to become cathodic, resulting in copper deposition from the
copper ions in solution.  At the same time, anodic dissolution must
occur to maintain charge conservation via this thermally driven
exchange plating or thermobattery effect.  In general what is
required for minimum dissolution of the circuitry is a donor metal
that is of equal or lesser nobility than the Cu metal/copper ion
system, also submerged in the plating solution and in electrical
contact with the region undergoing plating.  We have shown
experimentally that a copper wire is an ideal donor source for
plating up both copper and pure palladium without the presence of any
alternate donor source.

      We have shown experimentally that a very effective way for
providing material for anodic dissolution while also having contacts
that are highly wear-resistant is to use sharp tungsten probes
wrapped with thin (5-10-mil) bare copper...