[dorkbotsea-blabber] Soldering station + PCB ?

[flight]

Oh yeah, about those so-called "resist" pens - what you *actually* get
(usually) is a fine-tip Sharpie Industrial permanent marker. So, before you
buy a resist pen, compare prices. Some places just sell the normal Sharpie
marker, which doesn't work as well. What works even better are the Sharpie
acrylic paint pens - excellent.

Another tip: I can't recall where I found this but, a good cost-effective
technique is to use a sponge. Etching (at the molecular level) is
near-instantaneous, the long etching times are due to precipitant blocking
the process. Etchant agitators and bubblers are used to move the precipitate
out of the way so the acid can contact the copper. Problem is, they require
a LOT of etchant. Your average PCB really only needs a few mg of acid to be
etched! A good trick is (assuming you have an etching tray, gloves, goggles,
GOOD AIR CIRCULATION and, of course, some etchant) to pour some etchant (I
use Ferric Chloride since it is more aggressive) into a small plastic/glass
dish, dip a piece of sponge in it and rub the sponge on your board. The
rubbing action both applies etchant to the board AND moves the precipitant
out of the way. If your etchant is warm and the copper layer of your board
isn't too thick, you can etch a board in 10-15 minutes and only use an ounce
or so of etchant. The only trouble with this technique is you need your
resist to be rather sturdy to resist (heh) the abrasion of the sponge.
Resist pens wipe right off - use acrylic. Oh yeah - ferric Chloride (FeCl3),
being a Lewis acid, eats cellulose. So don't leave your sponge sitting in it
for long-term storage 'cause it'll turn into a nasty, gritty, goopy mess.
Trust me on this. On the other hand, it helps to get those paper fibers out
of the way. :)


~flight
flight at flightofharmony.com
http://www.fligthofharmony.com


-----Original Message-----
From: dorkbotsea-blabber-bounces at dorkbot.org
[mailto:dorkbotsea-blabber-bounces at dorkbot.org] On Behalf Of
rich at spambutcher.com
Sent: Sunday, June 22, 2008 2:35 PM
To: A discussion list for dorkbot-sea
Cc: alex at alexcphoto.com
Subject: Re: [dorkbotsea-blabber] Soldering station + PCB ?

> if you do have some accidental bridges on the board, you can
> fix them with an x-acto.

and if you have any place where the toner doesn't transfer - I've had 
luck with touching it up with acrylic paint (there's also "resist" pens 
made just for this - RadioShack includes one in their pc board kit)