Homebrew_PCBs

Hi all,

I'm thinking of making a DIY spray etcher, using sodium persulphate,
but wondered if you experts could answer some questions for me ;-)

In a professional spray etcher, are the boards horizontal? If so, is
the etchant sprayed from above or below? I'm worried that a
vertically hung board will result in uneven etching due to the
etchant running downwards, and a horizontal board sprayed from above
will quickly become covered in used etchant, reducing the
effectiveness of the fresh etchant arriving... Is spraying from
underneath possible/workable?

Does anyone have experience of professional spray etchers that they
could share with the group?

TIA

Duncan

Greetings!
I don't mean to advertise on this group but I think people should know about good software! Has everyone checked out protel 99se? www.protel.com It is an 8000 dollar software package but you can download the evaluation version which does EVERYTHING the real version does except that it does it for only 30 days. I downloaded the evaluation version and have fallen in love with it! :) It does schematic capture, simulation (XSPICE), and PCB (autoroute). If your graphics adapter is OpenGL compatible you can render your circuit board. This thing is sweet!
Hope it interests you!
Randy Knutson
Minnesota State University, Mankato



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Hi Randy,

I agree, it's nice. Got the CD (demo). But it's not Homebrew!
(meaning I don't know of ANY hobbyists buying it).

Alan KM6VV


Randy Knutson wrote:

>
> Greetings!
> I don't mean to advertise on this group but I think people should know about good software! Has everyone checked out protel 99se? www.protel.com It is an 8000 dollar software package but you can download the evaluation version which does EVERYTHING the real version does except that it does it for only 30 days. I downloaded the evaluation version and have fallen in love with it! :) It does schematic capture, simulation (XSPICE), and PCB (autoroute). If your graphics adapter is OpenGL compatible you can render your circuit board. This thing is sweet!
> Hope it interests you!
> Randy Knutson
> Minnesota State University, Mankato

Why not just experiment with water until it just 'looks' right. Most spray
etcher are horizontal. Vertical spray etching will have lot more etchant
running down at the bottom of the panel. I don't think you need to worry
about supply of fresh etchant with spraying, the pressure will quickly remove
any reactive products with its force. I wouldn't yet worry about differences
with etching rates on top and bottom. There are probably lot more important
things to consider first, like pump pressure, nozzle shape, nozzle
positioning and filtration. I thought about building my own but it started to
get too complicated and expensive. I think bubble agitation still has a lot
to offer provided you use an adequate air supply. I'm still looking around
for a cheap small regenerative air blower or a large diaphragm pump like
those used in aeration of septic tanks, and large fish ponds. These pumps
sell for $400 to $600 new in Australia. Not a viable option for a hobbyist.

Adam


duncanbourne wrote:

> Hi all,
>
> I'm thinking of making a DIY spray etcher, using sodium persulphate,
> but wondered if you experts could answer some questions for me ;-)
>
> In a professional spray etcher, are the boards horizontal? If so, is
> the etchant sprayed from above or below? I'm worried that a
> vertically hung board will result in uneven etching due to the
> etchant running downwards, and a horizontal board sprayed from above
> will quickly become covered in used etchant, reducing the
> effectiveness of the fresh etchant arriving... Is spraying from
> underneath possible/workable?
>
> Does anyone have experience of professional spray etchers that they
> could share with the group?
>
> TIA
>
> Duncan
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> To unsubscribe from this group, send an email to:
> Homebrew_PCBs-unsubscribe@yahoogroups.com
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

Homebrew PCBs doesn't always mean hobbiest!

I often "homebrew" or "lab brew" a PCB when I don't
want to wait for one to come back from a board shop. I homebrewed a board yesterday afternoon that
was 7 mil traces and 5 mil spaces. A 48 pin TSOP flash rom to DIP adapter for my programmer. It took
under an hour from Protel design to etched and drilled board.

later,
Larry E.

----- Original Message -----
From: Alan Marconett KM6VV
To: Homebrew_PCBs@yahoogroups.com
Sent: Monday, June 03, 2002 5:56 PM
Subject: Re: [Homebrew_PCBs] Spray Etcher Geometry


Hi Randy,

I agree, it's nice. Got the CD (demo). But it's not Homebrew!
(meaning I don't know of ANY hobbyists buying it).

Alan KM6VV


Randy Knutson wrote:
>
> Greetings!
> I don't mean to advertise on this group but I think people should know about good software! Has everyone checked out protel 99se? www.protel.com It is an 8000 dollar software package but you can download the evaluation version which does EVERYTHING the real version does except that it does it for only 30 days. I downloaded the evaluation version and have fallen in love with it! :) It does schematic capture, simulation (XSPICE), and PCB (autoroute). If your graphics adapter is OpenGL compatible you can render your circuit board. This thing is sweet!
> Hope it interests you!
> Randy Knutson
> Minnesota State University, Mankato


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