Homebrew PCBs

I currently etch all the boards I've made so far. I've used
photoetching, manually applied rub-on transfers and drafting tape,
and even cut the pattern on a vinyl sign cutter and used the vinyl
as a directly applied etch resist. I used to make transparencies
for photoetching manually using paint, markers, drafting tape,
rub-on transfers, and a copy machine. I sprayed boards with the
photosensitive spray rather than buying pre-sensitive ones. This
was long, long ago, like 20 years. At that time, I recall the
Positive pre-sensitive boards I could get were a pain to use for a
variety of reasons. That has changed.

I also liked being able to cut the boards to size and shape before
coating them, otherwise I had to be so dainty not to ruin the
pre-sensitized ones.

I want to build a mill/engraver because I have other uses for it,
too.

I've drilled out a pen for my HP plotter and superglued a carbide
scratching tip into it. I'm going to try the method brainstormed by
members here of spraying the board with blue metal marking fluid
and scratching off the path to be etched.

In my manual tests I discovered that thickness of the coat seemed
to be less important to success than making sure you allow the coat
to dry completely. After a few hours of drying, scratching across
the coat would pull up a scraggly wide path. After a day it was a
nice neat thin line.

John came up with the idea, someone else tested it manually with
Dykem marking fluid. Has anyone tested it in a plotter yet? When I
do, I'll write something up and add it to the Files section.

Hey, you can get that marking fluid in a bottle, I mean not just as
a spray coat. Might it work in a drafting pen? May be too thick for
a felt tipped pen like the HP plotter uses. I'm just thinking that
it is cheaper and easier to find than Staedler 313 refill ink.

But I really like the idea of scratching isolation paths, saves -a-
-lot- on acid.

Remember, everyone, to check the Bookmarks section and feel free to
add to it. I went to some trouble to set up Folders so please use
them. There are links there to all kinds of methods, software,
suppliers, etc.

Steve Greenfield

--- ph4appl <ph4appl@...> wrote:
> Etching works great for me as well. I have etched many boards by 
> printing with a bubble jet onto overhead projector transparencies
> and 
> using them as a mask to expose the pre-sensitized boards to UV
> light. 
> It is somewhat time consuming, but doesn't require as much
> accuracy 
> as milling the traces. One drawback is that it seems like if you
> get 
> a tiny drop of copper sulphate anywhere and it somehow
> rehydrates, 
> you have the stuff all over the place. 
> 
> I converted to CNC milling the boards because it was a cool
> project 
> to build and it is fun to watch. The acid isn't all that fun to
> watch.
> 
> Dave 


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