Hi everyone,

I am having some defluxing problems which I know have been common to the
industry for some time. However, I live in the hope that there may be some new
thinking on it - namely, the removal of rosin flux from underneath PLCC's. We
use an RMA based flux in our solder paste and, inevitably, flux is trapped
underneath these zero stand off PLCC's. The board design even has a small
square area of solder resist under each PLCC which negates any slight stand off
we may have had. Our main de-fluxing process using vapour phase HCFC does not
clean underneath and we're left with signs of rosin leaching out in many areas.
I have already tried an overnight soak in IPA in an attempt to soak it out
however, on baking off the IPA, more rosin bubbles out ! I do have a
semi-aqueous system however I'm hesitant to use this since I don't want to
entrap solvent and/or water under these components and cause myself more severe
problems. Any comments / suggestions out there ? By the way, due to customer
requirements, I can't go no-clean. Thanks in advance

Bryan Kerr Alenia Marconi Scotland

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