Boy are you going back in time. Plasma, if set properly should give you your
positive etchback. No need to sulfuric.

Scott Westheimer
----- Original Message -----
From: "Robert Coburn" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, April 21, 2005 8:55 AM
Subject: [TN] Concentrated Sulfuric etchback


> Hi T'Netters:
>
> One of our divisions has a design that requires positive etchback on a
> four
> layer PCB (FR4 resin system).
> The board shop that had previously provided these boards subcontracted to
> a
> Plasma service.
> The etchback does not meet requirements.
>
> Does anyone have a contact that can provide a concentrated Sulfuric acid,
> Ammonium Biflouride etchback?
>
> TIA,
> Regards,
> Rob
>
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