Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "Phil" <phil1960us@y...> wrote:
> 
> a couple of questions:
> - what is the width of the line produced by the fine point tip? 
> ultrafine?

I get lines of 0.025" max. Thinner lines are possible with less
pressure but 25 mill works fine for me.



> - what are the wear characteristics?  I assume the tip widens as it
> wears.  The tips of sharpies I have used have also tended to become
> flexible over time.

After a few dozen boards I notice little wear. Not cleaning the board
with steel wool before plotting would probably help by reducing
friction. Any widening that occurs seems to be from the Pen Down
impact. There is a lot of this when plotting text. The short answer
is: I haven't had a problem; change the pen when it starts to wear.
They're only a couple of dollars, US.



> - how is the ink different from the "office" grade sharpies?

I went on at length in my original post about the ink characteristics.
It is totally resistant against ferric chloride and does not allow
pitting like all the other pens I've tried.

The ink was originally developed for marking laboratory glassware. It
was designed to remain on glassware through steam sterilization to 500
F, resist acids, bases and many solvents. 

It does resist several solvents I've tried to use to strip the ink
after etching. IPA, acetone, and ethyl acetate. Something more
aggressive like MEK, Naphtha, or a solvent cocktail like "Goof Off"
might work better but I stay away from the really nasty ones for
health reasons. I just use super fine steel wool to take the ink off.



This is the perfect etch-resist pen. A quantum step above even the
etch-resist pens sold by the DIY PCB companies.

Might be interesting if the absorbent fiber ink tube in the pen could
have the ink squeezed out of it and use the ink in a standard plotter
pen or even better, inserted into a modified inkjet cartridge. I've
noticed that when marking on glass the ink does not puddle up but
stays put in a thin film.