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A Method for Producing Planar Repair Structures for Opens On Circuit Boards

IP.com Disclosure Number: IPCOM000103524D
Original Publication Date: 1990-Dec-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 1 page(s) / 72K

Publishing Venue

IBM

Related People

Partridge, J: AUTHOR [+2]

Abstract

A number of techniques have recently been described for achieving the successful repair of open copper circuits. One method uses laser seeding of the open from a metallorganic to produce a thin conducting layer of metal between the open ends. This is followed by immersion of the repair section in acidified copper sulfate solution with passage of AC current through the circuit net. This step causes a buildup of the seed layer with plated copper via thermally driven exchange plating. A second method avoids the seeding step and uses unacidified copper sulfate solution with an AC current to build a small copper bridge between the open ends as a first step. This is followed by additional AC-driven exchange plating in acid copper to increase the cross-sectional area of the initial bridge.

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A Method for Producing Planar Repair Structures for Opens On Circuit Boards

      A number of techniques have recently been described for
achieving the successful repair of open copper circuits. One method
uses laser seeding of the open from a metallorganic to produce a thin
conducting layer of metal between the open ends.  This is followed by
immersion of the repair section in acidified copper sulfate solution
with passage of AC current through the circuit net.  This step causes
a buildup of the seed layer with plated copper via thermally driven
exchange plating.  A second method avoids the seeding step and uses
unacidified copper sulfate solution with an AC current to build a
small copper bridge between the open ends as a first step.  This is
followed by additional AC-driven exchange plating in acid copper to
increase the cross-sectional area of the initial bridge. While the
latter technique is simpler since it avoids the seeding step, it
suffers from the possibility that, for large opens, i.e., gaps of
order or larger than the line width, the initial bridge may not be
planar and not in contact with the circuit board.  Planarity is, in
general, very important in present-day circuit board technology and
contact of a repair with the circuit board enhances its stability and
durability.

      We describe a method of improving circuit repair without the
use of seeding, i.e., the second of the two methods just described.
We have found that planarity of the repair can be achieved by
covering the region to...