I made quite a few back in the late 70's early 80's with my employer then.
Out of convenience I always silk screen printed the pattern on a well cleaned
board blank using the same ink used for making exhibit signs - that was the
primary purpose of the screen printing shop - as the resist.
Ferric chloride as the etchant, pre mixed to concentration.
The key was the etching process. A table top tank which held the boards
vertically and sprayed heated etchant on them. My recollection is that the
pattern was fully etched after no more than 5-10 minutes and there was never
any undercut of the resist. The key is the time to etch. The longer it takes,
the more that the resist will be undercut.
Al
AB2ZY
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Roger
(K8RI) on TT
Sent: Sunday, August 03, 2014 11:39 AM
To: towertalk@contesting.com
Subject: [TowerTalk] How do you get a good looking trace when etching?
Over the years I've tried etching boards with various methods. I have never
gotten a good looking trace. Whether the trace area is cleaned and painted on,
or photo sensitive, the edges are always irregular. They are not straight and
taper to a thin edge. Just what you don't want.
Temp, chemicals (Typically Ferric Chloride IIRC), chemical dilution,
agitation: All according to directions with the same results. I finally gave
up.
73
Roger (K8RI)
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