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Try doing a copper purge.
We purge copper from our solder wave by cooling the pot to just above
freezing for 12 (or more) hours. The copper forms 1-3 balls that we
scoop out. This generally reduces copper concentration from .2% to
less than measurable.
This can be done on a weekend.
I don't see why you can't do something similar.
Aric Parr
United Technologies Electronic Controls
______________________________ Reply Separator _________________________________
Subject: FAB: HASL drossing
Author: [log in to unmask] at internet
Date: 8/5/96 2:42 PM
Hello Technet,
We are having difficulty maintaining our HASL pot below 0.25% Cu, even
with 2x daily drossing. The machine is an old vertical Electrovert
with less than easy access.
- Is this 0.25% more critical at assembly than at fab?
- What is the practical USL for copper in HASL?
- How often should metal contaminants be measured?
- Should drossing be done at a constant frequency, or based on panel
loading?
- Are there any studies out there correlating HASL quality with Cu
contamination level?
- Any special recommended procedures or tools?
As always, we appreciate any input.
Joe Felts
PC World, Toronto
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