Homebrew PCBs

The copper wire in my Coleman cooler half full of etchant is getting
smaller and smaller in diameter, and lots of it has disapeared into
solution, but it seems it has been going slowly. So when I saw a used
vacuum pump/air source for sale (cheap) today, what could I do? This
has a higher volume output - over 2 CFM at 2 or 3 psig. It really has
the etchant "boiling" away. I hope the extra air will spead up
oxygenating the etchant and getting the copper dissolved, and the
etchant turned green/blue and ready to etch, much faster. (The newer
pump is a newer design with a magnetically driven piston; apparently
the piston is the only moving part. I will keep the old carbon vane
Gast vacuum pump for backup; I was not sure how to maintain it, or how
long it would last.)

The splashes of dark brown etchant on the walls of the cooler slowly
turn this beautiful green blue color as they soak up oxygen from the
air - kind of looks pretty.

The agitation from this much bubbling air is very substantial. I don't
think that an etchant pump would add anything over this level of
agitation - have to wait and see what kind of etch times I get. The
air sparger design from Think and Tinker is designed more for
agitation, I think, than fine bubbling, which apparently would
oxygenate faster than the big bubble type.

I hope to be etching boards soon.

Grant

The copper wire in the etchant is almost all gone. I will have to put
on my rubber gloves and go fishing tomorrow to see how much wire, if
any, is actually left. The etchant solution remains a dark 'coca cola'
brown, though spatters on the walls of the tank and lid are a bright
geen-blue.

The ph of the etchant has been 2 for the past 3-4 days, according to
some litmus paper I picked up. However, tonight the ph is 3. Does this
mean the etchant needs more HCl?

I bought a 12" airstone today and turned off the sparger tonight,
running the airstone instead on a lower volume of air. The bubbles
certainly are much smaller than the sparger's. I will wait and see
tomorrow if the etchant is changing color at all.

Though the process has been slow, it is working. Since I am in no
great hurry, I am ok with slow, though if I find a way to speed things
I will try it. I will let the group know when I do get there - to PCB
etching.

Grant