Interesting question. I think its pretty much an insulator since it
gets picked up via static electricity prior to fusing. I think a
conductor would have problems. but I just tried a quick test with
my multimeter and got nothing. maybe its an issue but i haven't seen
any problems, yet.
--- In
Homebrew_PCBs@yahoogroups.com, "ballendo" <ballendo@y...>
wrote:
> Phil,
>
> Thank you for a really detailed useful post!
>
> One question: Do you worry about the conductivity of the
> toner "screen print"? Seems that it could be an issue...
>
> Ballendo
>
> --- In Homebrew_PCBs@yahoogroups.com, "Phil" <phil1960us@y...>
wrote:
> > After trying lots of paper and making a few boards with magazine
> > paper, I found just the right paper and a good technique. I'm
very
> > pleased with the results for both 1 and 2 sided boards. Up until
> > now, I was pretty dissapointed with the quality of what i was
> making -
> > lots of trace blooming and areas of poor resist adhesion.. I
know
> > others have different techniques that work but this is getting
darn
> > near fool proof for me.
> >
> > The paper is general purpose good quality inkjet paper - less
than
> $5
> > for 500. I use a canon personal copier to get toner onto the
paper
> > and crank the darkness up quite a bit. The toner goes on thick,
> the
> > paper absorbs the excess toner nicely and I get very very little
> > blooming of my traces anymore.
> >
> > Copper substrate prep is pretty standard except I use emery cloth
> at
> > 220 grit to significanly increase the surface area to improve
toner
> > bonding. I'm going to try something finer than that. wash,
degrease
> > and dry in oven.
> >
> > I put the iron on just a touch back from the hottest setting
> > (cotton). I also use children's construction paper between the
> iron
> > and the toner paper as a pad to even out the pressure which I
apply
> > quite liberally. I iron both sides for a minute at what my
> bathroom
> > scale says is 30 lbs of pressure. Finally, I leave the iron on
top
> > of the board/paper assembly and turn it off to let it cool down.
> > This is an important step as it keeps the melted toner in strong
> > contact with the copper substrate to ensure good bonding. Once
> cool
> > enough to handle, it goes into the water for a standard soak and
> > rub. The paper falls apart very quickly and the toner doesn't
> flake
> > off at all so I can scrub pretty hard.
> >
> > Also, I am getting good results with legend printing (some times
> > called silk screen). I use the above technique with 2 changes.
> > First one is that after one minute of ironing, I use the edge of
> the
> > iron to "burnish" the toner paper into the board. This ensures
> good
> > contact of the hot toner to all surfaces including next to
traces.
> > The second one is that I do a hot peel of the toner paper.
Enough
> > toner stays on the board to be very legable but more importantly,
> no
> > soak-n-rub cycle and thus I can go right to drilling with no more
> > than a 5 minute delay.
> >
> > some pix taken with a 10X microscope
> > http://www.geocities.com/phil1960us/pcb/
> >
> > Phil