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Thu, 14 Jan 1999 14:43:29 -0500 |
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Donn,
A few things to consider:
OSPs are typically sensitive to temperature excursion in that it
promotes further migration of copper into the organic deposit, a condition
that can closely resemble a soldering environment not unlike exposed,
bare copper. In addition, high heat conditions will degrade the organic
coating resulting in "dead bodies" with different properties of the
original coating. These artifacts will not disassociate as a fresh coating
would and can act as a barrier.
In keeping with the disassociation scenario, it is a fundamental
function of the OSP to dissolve in contact with the flux components
allowing them to be displaced and solder to occupy the vacant space.
No clean materials are, by design, are less chemically active, and have
less inherent ability to attack the coating. Increasing chemical
activity will be counter productive.
I suggest a reassessment of storage conditions and duration. Attention to
flux application volumes, thermal conditions and flux type could help to
achieve control.
JMW
TET/Halco
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