I finally collected enough bits and pieces to do CuCl etching
(although it's still HCl etching). I've been collecting stuff for
quite some time now, HCl, H2O2, NaOH, beakers, etch tank, hydrometer,
etc. Also built a separate chemistry bench with a vent fan and sink.
I also took the time to do a "print survey" of all my laser printers
(I've got three functioning ones at the moment) and toner cartridges
(three for one of the 4P's) to find the best one. Turns out the old
HP 4P produces much crisper prints than the new (and faster) HP 2550.
I suspect it's a combination of "black only" and "slower path".
Anyway, I etched my bloat board, which I've mentioned here before. It
is just a grid of various line/space samples, with tweaks
(bloat/shrink) to the lines to try to compensate for the process. My
goal was to get a reliable 5/5 etch, but I'm not quite there yet. The
solution is a faint green now! :-)
The 6.67/6.67 rules seem to have worked reliably, although everything
was over-etched (new HCl solution). The 5/5 rules were barely
passable if I shrunk the traces by a pixel (i.e. 3.33/6.67 rules).
The regular 5/5 pattern had a few shorts in it. I haven't tried
5/6.67 rules yet.
Photos at
http://www.delorie.com/pcb/lab/