I have used electrical tape, Kapton tape, and packaging tape as an etch resist at various times, with moderate success. Often the etchant leaks under the tape edges, so fine lines disappear in spots, but with wide enough traces it is not bad. Spray paint works well if you have a good way to remove it where you want to etch. I had access to a laser system at work a few years ago, and it was great for removing paint. Paint is not very good solder resist however, it tends to melt when you solder.
One technique I have used with paint is to just etch narrow lines between "islands" of copper (all pads on one net are an island). I saved my Protel PCB as a DXF file and imported it into Autocad. Then I draw straight lines between islands on a separate layer for each side of the PCB. I print the line layers only (one side gets mirrored first), and tape to the PCB. I then use an exacto knife or sharp scribe to scratch the paint off along the lines, and drop into etchant. The amount of copper removed is almost zero, so the etchant lasts for many boards.
This is a lot of work, and results vary, but for a simple board it is OK. To be honest, if your time is worth anything and you have PCB layout software that creates Gerber files, you are far ahead to send them out to be fabricated. I usually use PCB Express (aka Sunstone Circuits). Top quality work, fast turn, and you get plated thru holes, solder mask, and silk screened legend. I haven't used them for a couple of years, but I used to lay out several different designs on one large panel, and order minimum quantity of panels. I could get a lot of boards for under $100.
Bob
--- On Tue, 11/10/09, leon Heller <leon355@...> wrote:
From: leon Heller <leon355@...>
Subject: Re: [Homebrew_PCBs] tape for resist?
To: Homebrew_PCBs@yahoogroups.com
Date: Tuesday, November 10, 2009, 9:12 AM
----- Original Message -----
From: "cary heestand" <c.hhestand@att. net>
To: <Homebrew_PCBs@ yahoogroups. com>
Sent: Tuesday, November 10, 2009 3:47 PM
Subject: Re: [Homebrew_PCBs] tape for resist?
Thank you all for the great replies!
Leakage on the edges won't be a problem.
I originally was going to use a "ball shaped burr" in a dremel tool and
still might go that way. But then thought about using tape and etching.
I didn't know you could use a Sharpie on it's own. I thought that was just
for repair of toner transfer.
Spray paint will work? For what I have to do that might be the way to go.
Then I could just remove the paint where the pads are and leave the rest of
paint as a solder mask!
I used to use cellulose paint as etch resist.
Leon
[Non-text portions of this message have been removed]