I am not a board guru, so I cannot answer your question. But I have seen
the same type of rough etching, especially on very small pads like for
flipchips, and on very fine traces that need to be kept to less than 6
mils in width and very straight for high impedance/high frequency
applications. There are not too many board shops that can etch these
small features consistently and do a good job of it.
However, some of these board houses are now able to mechanically route
out the copper using either laser-etching or ball milling techniques.
They do this on the portions of the circuit that need this precision,
and use standard etching processes for the rest of the circuit. I do not
know how they are able to do it on several layers, but they can. You may
wish to find a board vendor that can do this type of mechanical copper
removal.
 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Scott Decker
Sent: Thursday, February 23, 2006 1:34 PM
To: [log in to unmask]
Subject: [TN] Board etching question for you board shops out there.

All you board gurus out there, I have a question for you.
   What are the reason(s) I see traces that look like a mouse has
nibbled on the copper to etch it, as opposed to acid etching the copper?
I'm looking at some boards that look like the resist was put on by a
drunk with an old marker pen! The vias are not even round and the SMD
lands have ragged edges also. This shop is off my list from here on out
and going to be rebuilding some boards due to minimum trace problems
too, but can anyone tell me what causes the ragged edges like that? I
understand that specs are looking at averages, which means a high and
low end of the spectrum. I think I know who put the low numbers into the
pot. :-( Thanks for any info.

Scott Decker
AKA: Padmasterson
Broad Reach Engineering CAE
Ph. 480-377-0400 Ext. 34
FAX. 480-968-4597
Tempe, AZ.


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