Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

----- Original Message -----
From: "jimofc300" <jim@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, January 04, 2010 7:59 AM
Subject: [Homebrew_PCBs] Newbie questions


> Hi,
>
> While I'm an experienced design engineer, I've never done a PC board in
> 40+ years of design. We had a special department to do that. Now retired,
> I thought I'd try inventing. I find PCBs important to that goal.
>
> In getting together a kit to do this, I had a few thoughts and questions.
> I hope you more experienced (though not necessarily older) and
> (presumably) wiser folks :-) can address some of these questions.
>
> 1) I've looked into photo paper and "Press-N-Peel" to transfer toner as
> resist. Do you think laser T-shirt transfer paper, which is probably
> cheaper, would work, too? Has someone tried this?

I tried it years ago, it just makes a nasty mess on the board.

>
> 2) Do you think latex gloves, as you'd find in a doctor's office, would
> be safe for handling boards and etchant? They're cheap at Walgreens and
> disposable to reduce cleanup effort.

I use ordinary kitchen rubber gloves. Latex is too thin and you will burn
your hands.

>
> 3) If ferric chloride wouldn't destroy them, would kitchen plastic bags
> (ZipLock-type) work for etching boards? They'd probably save on etchant
> and, if I don't slop too much, reduce cleanup.

Ziplock bags work, apparently. Put the bag etc. in very hot water. I use a
small plastic food container in an old washing uip bowl with about 1" of
very hot water in it. WEtching takes about 5 mins with fresh etchant.


>
> 4) How nasty is used ferric chloride? Is it a HazMat material? How do you
> folks dispose of it in an eco-friendly manner?

Ferric chloride is quite safe, it's actually used in water treatment. Don't
get it in your eyes, though.

>
> 5) Would Krylon spray clear coating and/or spray paint work as a solder
> mask? My thought is to spray the board immediately after etching and
> touch-up. Then, I would assume, soldering would burn off the paint
> instantly. Would a second coat be necessary after assembly?

You can buy a proper spray-on flux, which helps soldering, or a special
lacquer, which burns through when soldering. I don't bother, as I use
photo-etch and my boards don't oxidise because of the thin film of resist
remaining on the copper.

Leon