gEDA-user: CuCl comments from a user - was - Re: PCM making methods - was - Re: alarm clock update

[andrewm <andrewm@xxxxxxxxxxxxxxx>]

Tools,

I use a car battery hygrometer for measuring density.  The car battery 
hygrometers do not cover the full range of acceptable densities for 
etching but does cover the optimum.

For acid measurements I do periodically titrate using the method given 
by Adam in his page.  Most of the time I just add a dash of acid at the 
start of each session. (A pinch of salt, two cloves of garlic and splash 
of white wine)

I bubble during etching and for a while afterwards to regenerate the 
mixture.  Also my tank is about 5 times bigger than I would use if I was 
using FeCl.  If you have a lot of spare etching capacity you wont ever 
run into copper saturation.

The etchant does grow but very very slowly.  In fact it does not grow 
fast enough for me to give it away.  Most people I know want to start 
using it when they see it so I have to throw extra scrap copper in and 
bubble for days to get extra etchant to give away. (I am always titrate 
after eating a lot of copper to grow the bath)

The air DOES regenerate it completly.  You don't need to add H2O2.  But 
I do keep some H2O2 spare in case I need to do a lot of etching at 
once.  The H2O2 gives you an instant regeneration rather than having to 
wait hours.

The etch rate I get is a little slower than FeCl3.  However it does not 
give as good an edge as the FeCl.  It gives as good a detail as H2O2/HCl 
or amonia persulphate.  In my experience none of them compete with FeCl3 
for resolution.  If you run CuCl (or H2O2/HCl) at elevated temp then the 
speed can be better than FeCl3 but at the expense of more undercutting.

I only run my etchant at 30 degrees C.  At 40 degrees C (105F) I get a 
bit much fuming for my likeing (I probably keep it too green and too 
high in acid most the time)




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