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Subject: Re: [Homebrew_PCBs] Re: Ammonium Persulphate

From: "Stefan Trethan" <stefan_trethan@...>
Date: 2006-06-07

On Wed, 07 Jun 2006 00:50:10 +0200, Andrew <andrewm1973@...> wrote:

> It takes some time to make.
Not really, if you start with HCl and H2O2 you can immediately etch boards
and just have it grow. Remember the other etchants are usually made up
from powder or crystals as well, unless you get bottled FeCl.

> It takes some time to look after before use.
Does it? I usually drop the board right in and then add some H2O2 if i
believe it is too dark to make the board. Every few months (if i feel like
it) i'll measure molarity and add HCl, usually while waiting for a board
to etch.

> As you pointed out it takes some space.
It does, but the other etchants require some too (maybe less though).

> Vapours from it can wreak things.
Indeed that is an issue. You need a lid on the tank. I have found it
doesn't have to be totally airtight but it should be closed.

> It does not etch as well as FeCl in an air
> agitated tank. (line resolution)

Ok.

> You can't see the board like Amonia
> Persulphate. (which may be good thing if
> you only do a few boards and are not too
> familiar with etching)

That's not the case if you use a narrow tank (say an inch wide max.) and a
light from the back. Either a torch or recently i found those small garage
fluorescent lights that you usually stick inside a car work well too
because the light is nice and even.

> Your neighbours look at you funny and call
> the anti-terrorisim hotline when you are
> using it outside.

Don't show them ;-). The other etchants may cause funny looks too...

ST