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April 2003

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From:
"Cyker, Howard A (Howie)" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 22 Apr 2003 08:54:11 -0400
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Hi Prashant,

It's been a few years since we processes gold finger boards, but when we did
we covered the fingers with Kapton tape prior to delivering the PWBs to the
assembly areas.  The tape was applied either by the PWB vendor or in a
prepping area and remained on the boards throughout all assembly operations
(double-sided SMT reflow + wave solder) which included occasional cleaning
(IPA and/or EC-7 (citrus extract based) spray) of solder paste on
mis-printed boards.  The tape was removed after all assembly operations, the
gold fingers were then cleaned (IPA I believe) and then lubricated (paraffin
wax solution) prior to shipping.  As we never experienced systematic pitting
problems as you describe, I suspect that your problem may be with the
plating itself or perhaps improper taping.

Howard A. Cyker
Lucent Technologies
Engineering Infrastructure - New Product Engineering
Email [log in to unmask]




-----Original Message-----
From: Prashant Chopra [mailto:[log in to unmask]]
Sent: Tuesday, April 22, 2003 2:59 AM
To: [log in to unmask]
Subject: [TN] problem with gold pads of the pcb


hi all,

we are using gold finger pads on the pcb. but after going thru smt process
of screen printing,component insertion, reflow and aqueous wash we are
facing the problem of grey color dots on the pads.

This problem is with the pads where no components are being placed.

There is no solder paste printing on these pads nor any components are
place there and they are being covered with Kapton tape thru out the above
process.


Can anyone point to some reasons for this problem?????

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