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| Date: | Thu, 22 Aug 1996 04:38:56 EDT |
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TO: I4235700 IBMMAIL IBM Mail exchange
FROM: DSTEWART EX2 D.Stewart - Product Development Manager.
DATE: 22 August 1996
SUBJECT: CAUSE AND CORRECTIVE ACTIONS FOR PINK RING AND WEDGE VOIDS..
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TO: TECHNET IBMMAIL IBM Mail exchange
FROM: DSTEWART EX2 D.Stewart - Product Development Manager.
DATE: 22 August 1996
SUBJECT: CAUSE AND CORRECTIVE ACTIONS FOR PINK RING AND WEDGE VOIDS..
Re-pink ring and wedge voids
Certainly using reduced oxide will eliminate pink ring and
therefore wedge voids, as long as it is used correctly.
Issues to watch out for are: hold time between reduction and
lamination - we limit this to 72 hours maximum ; we do not stove
any layers prior to bond (haven't for years, even before reduced
oxide!) - stoving can/will cause reoxidation of the copper ; make
sure that the reduction chemistry is doing its job - we have a
process control of timing initiation time of the reducer, and how
much gassing is still going on at the time the panels are to be
removed from the bath ; finally, we also use a test vehicle on a
shift by shift basis to check that there are no 'high shorts' - a
problem caused by residual copper on the laminate from the etching
process which when oxidised is not conductive, but becomes
conductive again when the oxide is reduced.
Hope this helps
Dougal Stewart
Exacta Circuits
Scotland
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