I have been advised by our Materials Laboratory that the following 
     etch is excellent for defining cracks or grain structures of a 
     microsection:
     
     100mls DI water
     10g sodium dichromate
     2mls conc.sulphuric acid
     
     This has the advantage of not "going off" and keeps for a good six 
     months!
     
     Cotton swab for 5-10Secs
     
     Clive ffitch
     MBUK
______________________________ Reply Separator _________________________________
Subject: Microsectioning
Author:  [log in to unmask] at INTERNET
Date:    25-03-97 7:01


Technetters,
I am searching for the best way to etch a microsection. The way we 
currently do it is Hydrogen peroxide/ammonia. It seems inconsistent as 
it is used throughout the day. When the etch is new we get an extremely 
good line of demarcation between the clad and plated copper. 
Occasionally, we see  a line where the plater actually pulls the rack 
out of the bath,  plugs the hole and returns it to the bath for a higher 
thickness. We apply the etch with a cotton swab for approximately 10 
seconds.
     
I am  wondering if this is a common technique  for microsection etching? 
     
T.A. Gaylor 
     
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