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Self Aligning Pre-etch Step for Open Circuit Repair

IP.com Disclosure Number: IPCOM000121344D
Original Publication Date: 1991-Aug-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Vigliotti, DR: AUTHOR [+2]

Abstract

It has been shown in [1] that an open circuit, submerged in unacidified copper sulfate in conjunction with the passage of an AC current, can be used to grow copper dendrites across the open to electrically connect the two ends. Once this preliminary repair has been established, it becomes possible to use self-induced repair (SIR) as a second step to complete the repair, treating the ciruit as a near open or one having a narrow constriction [2]. One of the difficulties with this open repair technique is that dendrites tend to grow from corners when high frequency current is applied to the submerged copper circuits. The resulting copper connection will then not have the desired geometry, i.e., there will not necessarily be growth along the shortest path between the open ends.

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Self Aligning Pre-etch Step for Open Circuit Repair

      It has been shown in [1] that an open circuit, submerged
in unacidified copper sulfate in conjunction with the passage of an
AC current, can be used to grow copper dendrites across the open to
electrically connect the two ends.  Once this preliminary repair has
been established, it becomes possible to use self-induced repair
(SIR) as a second step to complete the repair, treating the ciruit as
a near open or one having a narrow constriction [2].  One of the
difficulties with this open repair technique is that dendrites tend
to grow from corners when high frequency current is applied to the
submerged copper circuits.  The resulting copper connection will then
not have the desired geometry, i.e., there will not necessarily be
growth along the shortest path between the open ends.  Instead, there
may be growth that extends past the outer edge of the circuit line
causing an effective widening of that portion of the circuit.

      The aforementioned problem can be circumvented by the steps
outlined in this article.  First the open circuit region is covered
with a droplet of, or submerged in, sulfuric acid (or a similar acid
that etches copper increasingly with higher temperature).  A
relatively high frequency (preferably kHz) AC current is now applied
to the circuit containing the open.  Local heating of the acid due to
the passage of the current gives rise to local copper etching.
Etching will be most rapi...