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January 1999

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Subject:
From:
Neil Roche <[log in to unmask]>
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

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
      to Paul Wareham <[log in to unmask]>

To:   [log in to unmask]
cc:    (bcc: Neil Roche/DOV/DIIG)
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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