Homebrew PCBs

Todd, I like your ideas.  What is a "swamp" cooler pump?  I am not familiar with drip irrigation spray heads.  Are they like mister nozzles for gardens?

Jeff

-----Original Message-----
From: Todd F. Carney <k7tfc@...>
Sent: Tuesday, January 29, 2013 2:35 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] thoughts on electric paint sprayer for spray etching

 
On Mon, Jan 28, 2013 at 8:47 PM, Jeff jeff.heiss@...> wrote:
 >
 > What are opinions on using an electric paint sprayer to spray etch a
 > board? Could an electric sprayer be modified to run etchant so it can
 > resist corroding? Would the spray pattern, droplet size, and spray force be
 > acceptable?
 >

 Jeff,

 Just to clarify, do you mean for the sprayer to resist corrosion? If you
 use ferric chloride, that doesn't seem likely. Maybe not even a persulfate
 etchant.

 I used to use shop-built bench-top (actually, lab-sink-top) spray-based
 etching machine that was pretty much all plastic. It consisted of an
 open-top plastic tank, an immersion heater (from a small hot-water heater),
 an immersion pump from a "swamp" cooler, and sprayers made of PVC pipe, and
 a holder that clamped the board to be etched in a frame. The sprayers hit
 the board evenly on both sides at once. The little spray heads were made
 for drip-irrigation use. We placed a sheet of plexiglass on top to contain
 overspray and so we could monitor the etching. We used persulfate etchant
 in it (which we left in it until it had to be replaced) so it was not a
 source of staining-or-toxic ferric chloride. I don't know how or if that
 damn stuff would work in such a machine. We never used it. I don't think
 any professional or commercial pcb outfits use it either.

 These days, a darkroom tray works for the one or two boards I might make in
 a month. I use home-made peroxide-muriatic-salt etchant. I just hand
 agitate the tray. I was toying with the idea of making a motorized rocking
 agitator, but then I came to my senses.

 73,

 Todd

 ----------------------------------------------------------
 K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
 ----------------------------------------------------------
 QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design

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