Hi Scott,

I can see where a concern could arise when dealing with tight impedance designs. However, Stripping poorly oxided panels and reoxiding is pretty common place. I suspect most of us ( at least I do ) use a microetch in our oxide line and use that same microetch to strip off oxide when something goes wrong. Although not frequent, I assure with oxide, something will eventually go wrong and panels will be stripped and re-oxided. 

I doubt there has been any significant problems assocaited with this process since I have seen more variation in supplied copper thickess that stripping oxide will create.  

Just my thoughts.....

Ed Cosper

----------
From:   D. Rooke
Sent:   Thursday, December 17, 1998 7:11 PM
To:     [log in to unmask]
Subject:        Re: [TN] Oxide rework

If a microetch is used to clean panels prior to oxide, the second pass
removes more rather than less copper. I would be very careful about multiple
passes through the oxide if microetch is present.

Dave Rooke
Viasystems Canada

-----Original Message-----
From: Scott B. Westheimer <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Wednesday, December 16, 1998 10:21 PM
Subject: [TN] Oxide rework


>Fellow Colleagues,
>
>Wondering if someone can tell me the industries stand on reworking inner
>layers at black oxide. Would like to get the point of view from both the
>PCB manufacturer and end user. I realize that controls need to be in
>place so that the layers are not over etched and signal lines are not
>reduced, especially for controlled impedance layers. The first time the
>boards were oxided they had 40u' of copper etched away and I believe
>that by reworking and removing 20-30u' this should not effect the
>functionality of the boards.
>
>You comments would be greatly appreciated.
>
>Scott Westhimer
>
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