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From: Ed Cosper <[log in to unmask]>
To: "'Darik Leung'" <[log in to unmask]>
Cc: "[log in to unmask]" <[log in to unmask]>
Subject: RE: Black-oxide layer turned red after pressing
Date: Thu, 13 Mar 1997 09:19:30 -0600
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Darick,
The anomaly we experienced manifested itself in several forms. One of =
the strangest was a reddish color on a single trace while all other =
traces surrounding it were black. I have heard this referred to a =
galvanization in the copper plating area but I'm not sure what causes =
this in oxide. By the way, if anyone out there knows the specifics or =
mechanics as to what causes this condition, I would like to know.
Thanks=20
Ed=20
----------
From: Darik Leung[SMTP:[log in to unmask]]
Sent: Wednesday, March 12, 1997 1:42 PM
To: Ed Cosper
Subject: Re: Black-oxide layer turned red after pressing
Ed Cosper wrote:
>=20
> Dear Darik,
>=20
> We experienced a similar problem a few years ago, we found that by =
putting in a caustic pre-dip and changing it out weekly, we problem went =
away. When we would try to extend the bath, it would gradually return. =
However, usually we could see a reddish color streaking before we =
pressed it. You might have to look close and angle the layer in a light =
source.
>=20
> Hope this help,
>=20
> Ed Cosper
> Director, Quality Assurance and Engineering
> Graphic Electronics, Inc.
>=20
> ----------
Thank you so much for your advice. We will try to investigation this
based on your suggestion.
Anyway, in your case, did it happened on all board design (not
particularly those with thin outer layer), and did the red area confined
near the edge of the platen? We did observed such symptoms.
Best Regards,
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======== Fwd by: Anthony (Tony ========
Hi Ed,
Give me a call if you would like to get more opinions on the cause of the
problem in the oxide process, I believe I can shed some light on the
problem.
Tony King
Elexsys International Inc.
Nashua N.H.
Phone: 603-886-0066
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