It's possible, depending on how adhered the mask is. My thought was not so
much on the undercut entrapping anything; however, once the adhered mask
began to separate from the glass of copper (at whatever stage), then it
would allow for entrapped 'stuff' at this newly formed pocket or space.

This of course could happen during assembly (from pre-clean to post-clean)
and while in use (environmental conditions, humidity, dust, dirt, etc).

Franklin



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kevin Glidden
Sent: Tuesday, September 26, 2006 12:52 PM
To: [log in to unmask]
Subject: Re: [TN] Over-developed Soldermask

Franklin,
The concern of the undercut trapping residues or contaminants is an
interesting point and one that I had not considered. Would that not also be
a concern during the initial soldering / cleaning steps that the flux
residues could get trapped in the undercuts?
Thanks!

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