Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Stephen Lane again:
No problems any questions I'll do my best to answer them.
The heat gun I use is a real hot one & I'm not sure of the actual
temp on the board I'm going to borrow a thermocouple from work & try &
measure it. The measure of "done" I used was based on what the toner
transfer method described when you do the second melt of the toner onto
the transfer paper (where it goes nice & shiny and any pin holes are
supposed to fill themselves in) here it goes a nice dry flat mat & emits
a bit of "steam" which I'm careful not to breath in.

re the Durabrite inks I have not found a supplier for Mispro in
Australia so if anyone can point one out I will be most grateful I have
found a supplier that says the OEM ink they supply is a pigment one but
it will cost as much to buy a set of new carts as to buy a bulk supply
on spec & then discover it won't work. As pointed out in the Forum the
Black Ink is a waste of time & so is the Durabrite Black, I put some
test stuff around the actual thing I wanted the first time & the brown
combo was the only thing that came thru unscathed which I was suitably
impressed with & grateful for the Forum for pointing out the possibilities.

Thru out all my experience in making PCBs in the kitchen (even small
runs at work when we had a design arm) I can not reiterate hard enough
how important a clean, grease free copper surface with some fine
scratches in it helps the whole process. Followed by the time between
cleaning to etching must be kept as quick as is safely possible to
minimize the effect of the oxidation that starts instantly the board
stops being cleaned (you only need to look at the black deposit on the
"lint free" tissue that you use to wipe it after drying with Acetone to
realize.that something is starting to happen even while your drying the
board).

Another thing to think about when laying out the Artwork is to not
have large expanses of Copper to etch away if you can help it, not only
does this load up your etchant it is usually the last bit to go & while
you were waiting the small tracks between the IC pads just got seriously
under cut reducing their current carrying capacity or plain disappeared
(hence my hint re the remove, wash, dry & touch up in the original
post). If I have big expanses of board that arn't needed I tend to pour
a fill into them or do a X hash with tracks, make an extra ground plain,
anything to make the amount to be etched to be the same average over all.
Anyway I'm probably beating on somebody else's drum as I have'nt had
time to peruse all the Archives & everything in the last couple of years
but these last points are the things that really help me.

Regards
Stephen Lane