Hi,
I remember there being a thread about this in the not to distant past (month
or two). Sorry I don't have any of the messages saved.


Robert Peterson
mailto:[log in to unmask]
<mailto:[log in to unmask]>

Alternate Final Finishes, Inc.
166 Middlesex St.
N. Chelmsford MA 01863
Phone (978) 251-7429     Fax (978) 251-7219
http://www.AlternateFinalFinishes.com
<http://www.alternatefinalfinishes.com/>


-----Original Message-----
From: Franklin [mailto:[log in to unmask]]
Sent: Friday, October 08, 1999 3:52 PM
To: [log in to unmask]
Subject: [TN] Micro-etch attacking copper when gold tabs are involved


Okay brainiac's, here's a stumper.

We are witnessing micro-etch attacking exposed copper circuitry only on
boards with gold tabs.

This occurs right at the copper to gold demarcation point.

This only just started, within two days.

No significant process changes have occurred. (normal replenishments, all
data looks nominal)

We first noticed it after we stripped off some poor white tin for rework.
When we inspected the boards before
the second trip through immersion tin, we saw reduced circuits, some to the
point of non-existing, pads etched away far beyond anything the micro-etch
should be capable of in the seconds we keep product in this bath.

From our supplier, they believe the gold is reacting with chemistry in the
micro-etch bath??????

Has anyone else witnessed this? And how'd you resolve it?

Thanks,

Franklin