John,
In todays world, if a PCB is properly cleaned after etch, deposition and
prior to mask, then acid traps should not be a concern.
We do a lot of weird angle stuff in the RF world and I have never seen a
failure due to acid trap type issues.
Bottom line is if your fabricator has good process then it should not be
an issue, but to keep risk to a minimum good design practice should be
followed when possible.
Hope it helps,
FNK 

Frank N Kimmey CID+
Principal PCB Designer
PCB Programs
Powerwave Technologies Inc
Office 916-941-3159
Fax 916-941-3195
Mobile 916-670-0645

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of John Foster
Sent: Tuesday, November 21, 2006 8:53 AM
To: [log in to unmask]
Subject: [TN] Acid Traps

I would like to ask the board fabricators if acid traps are a real
issue.

I normally try to avoid any feature that creates a structure that is
less
then 90 degrees.

However I am helping out another group by reviewing their boards and
there
are literally
hundreds of acid traps on the board. This board is class 3 and has to be
high reliability.

I have always been taught that they can be a real problem. But have
never
quite understood
why.

Any input on this will really be appreciated.

Thanks
John Foster

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