Homebrew_PCBs

Having read up a bit on CuCl2 etching, I can see that there are
quite a few advantages to using it, especially versus FeCl. I'm
wondering, though, about how critical the chemistry aspects of it
are to getting good results.

How difficult is it to determine that you've gotten the
concentrations of the various chemicals involved correct? How
difficult is it to maintain the etching solution in good condition?


Thanks, Bob

On Sat, 12 Feb 2005 02:30:57 -0000, Bob_xyz <bob_barr@...> wrote:

>
> Having read up a bit on CuCl2 etching, I can see that there are
> quite a few advantages to using it, especially versus FeCl. I'm
> wondering, though, about how critical the chemistry aspects of it
> are to getting good results.
> How difficult is it to determine that you've gotten the
> concentrations of the various chemicals involved correct? How
> difficult is it to maintain the etching solution in good condition?
> Thanks, Bob

It is harder than just mixing FeCl, but not that much.
It depends on how you like to work. If you are a person that likes to do
stuff "by gut feeling" then you needn't do any analysis and just go by
color and etchrate. If you are a person that likes to have 3 plans before
starting anything then you should get some analysis gear. You'd want a
hydrometer for density and the "two eyedropper" method for molarity (see
one page in the links). This gives you accurate information about the
bath, and you can maintain it without having any experience.
The hydrometer measures S.G., the molarity stuff measures how much HCl
you've got, and the color itself is a strong indicator of when to
regenerate.

There are some pages in the links section that describe overly complicated
stuff, like stirrers and so on. You neend't have any of that.

Even if you go for the simple analysis gear, it won't be very expensive.
As a hydrometer you might get away with using a car battery tester (the
thing with the rubber ball to suck up acid), but check if the range is OK
and keep in mind a real hydrometer would be more accurate.

ST

Stefan Trethan wrote:

> On Sat, 12 Feb 2005 02:30:57 -0000, Bob_xyz <bob_barr@...> wrote:
>
>
>>Having read up a bit on CuCl2 etching, I can see that there are
>>quite a few advantages to using it, especially versus FeCl. I'm
>>wondering, though, about how critical the chemistry aspects of it
>>are to getting good results.
>>How difficult is it to determine that you've gotten the
>>concentrations of the various chemicals involved correct? How
>>difficult is it to maintain the etching solution in good condition?
>>Thanks, Bob
>
>
> It is harder than just mixing FeCl, but not that much.
> It depends on how you like to work. If you are a person that likes to do
> stuff "by gut feeling" then you needn't do any analysis and just go by
> color and etchrate. If you are a person that likes to have 3 plans before
> starting anything then you should get some analysis gear. You'd want a
> hydrometer for density and the "two eyedropper" method for molarity (see
> one page in the links). This gives you accurate information about the
> bath, and you can maintain it without having any experience.
> The hydrometer measures S.G., the molarity stuff measures how much HCl
> you've got, and the color itself is a strong indicator of when to
> regenerate.
>
> There are some pages in the links section that describe overly complicated
> stuff, like stirrers and so on. You neend't have any of that.
>
> Even if you go for the simple analysis gear, it won't be very expensive.
> As a hydrometer you might get away with using a car battery tester (the
> thing with the rubber ball to suck up acid), but check if the range is OK
> and keep in mind a real hydrometer would be more accurate.
>
> ST
>

Having used the etchant for few months now, I would agree with
everything said above. A hydrometer, and a some droppers will get you
out of the dark when things aren't working right. Fortunately, the
accepted acid concentration range is very broad, so any capability of
measuring within a +-%33 error, will be good enough.


Adam