Homebrew PCBs

Robin,

Over time, I found that convection current etching didn't work so well for me. However, placing a translucent tub with 1/2" of etchant in it over a 200W incandescent bulb works great. It gently warms the liquid but more importantly, lets you see the copper dissolve. You can easily see the instant that a given trace has been isolated from the surrounding copper. A gentle rocking motion is all that I do.

Rick 

-----Original Message-----
From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] On Behalf Of Robin Whittle
Sent: Monday, July 29, 2013 10:01 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Rick Sparber's lamp-heated convection current etch technique

There's a PDF which I found interesting and don't recall being mentioned on the list:

  http://rick.sparber.org/electronics/el.htm

  Convection Etching of a Circuit Board
  http://rick.sparber.org/electronics/ce.pdf

in which a clear glass tray is filled with etchant, a lamp is placed underneath to illuminate and heat it, and the single-sided PCB is floated on the surface of the etchant.

The ferric chloride and citric acid etchant I use would be too opaque to use the illumination aspect of this technique, but it might be useful in terms of warming and promoting gentle circulation of etchant.

  FeCl + citric acid = Edinburgh Etch; HCl is transparent?
  http://tech.groups.yahoo.com/group/Homebrew_PCBs/message/30540
  2012-08-23

  - Robin