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Self Induced Repair Using Gated Ramping of AC Current to Limit the Thermal Spread

IP.com Disclosure Number: IPCOM000107376D
Original Publication Date: 1992-Feb-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 1 page(s) / 49K

Publishing Venue

IBM

Related People

Dreyfus, RW: AUTHOR [+3]

Abstract

Self-induced repair (SIR) was first introduced as a way of electrochemically repairing near-open circuits [*]. The method employs Joule heat supplied to the region of the circuit defect by a ramped AC current while the circuit is submerged in an acidified copper sulfate solution. The electrochemical mechanism is one of thermally enhanced exchange plating in which a local region (defect) of circuit becomes slightly warmer than the surrounding circuit. This, in turn, causes the defect to become cathodic, resulting in copper deposition which leads to the defect repair. At the same time, anodic dissolution occurs from the surrounding copper circuit metallurgy or copper bearing contact probes.

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Self Induced Repair Using Gated Ramping of AC Current to Limit the Thermal Spread

       Self-induced repair (SIR) was first introduced as a way
of electrochemically repairing near-open circuits [*].  The method
employs Joule heat supplied to the region of the circuit defect by a
ramped AC current while the circuit is submerged in an acidified
copper sulfate solution.  The electrochemical mechanism is one of
thermally enhanced exchange plating in which a local region (defect)
of circuit becomes slightly warmer than the surrounding circuit.
This, in turn, causes the defect to become cathodic, resulting in
copper deposition which leads to  the defect repair.  At the same
time, anodic dissolution occurs from  the surrounding copper circuit
metallurgy or copper bearing contact probes.

      One of the difficulties with the SIR technique, as circuit
dimensions become smaller and more closely spaced, is that proximity
plating can occur.  Thus, as Joule heat is supplied to the circuit to
be repaired, thermal gradients can be established in nearby copper
metallurgy.  A portion of the metallurgy then becomes heated above
ambient and will also become plated, a very undesirable feature.

      To avoid or minimize the aforementioned difficulty is the
object of this article.  What is recommended is the ramping of the AC
current in a gated fashion in order to minimize the heat flow to the
surrounding circuit.  A good rule of thumb, based on the
one-dimensional hea...