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Reply To: | TechNet E-Mail Forum. |
Date: | Fri, 22 Jan 1999 14:35:21 +0000 |
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Hi Paul,
The I've seen tarnishing of this type twice before , in both cases it was
due to the washing process.
1. Water not being completely wiped from the component bodies by the
turbine
blowers prior to IR drying - This burnt the water off the body leaving
the discoloured
finish on the metal surface.
2. The other occasion, which I don't think applies to your crystals, was
a reaction between
an anodized metal surface and saponifiers in the wash.
If you manually dry the boards by intervening between the blower & IR
sections it should confirm or
rule out my suspicions.
Hope it helps.
Neil Roche.
Paul Wareham <[log in to unmask]> on 22/01/99 01:50:51
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Subject: [TN] Tarnished marks on crystals
We are using a Fox type HC49U crystal on one of our boards and after wave
solder and washing, the body the crystal seems to be tarnished or
discolored with a yellowish tint. It does not appear to be a residue and
the rest of the board is clean.
Any idea what could caue this kind of stain anyone?
Paul Wareham
DynaGen Systems Inc.
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