Pumice spines can break off into the copper and are very difficult to remove.  These
spines can tent up the photo resist leading to etch defects.

Chuck Brummer
Acuson

"" wrote:

> Pumice distorts thin layers, and causes problems when they are laminated.
> Folks seem to prefer wet chemical approaches for this reason alone..
>
> Rudy Sedlak
> RD Chemical Company
>
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