Homebrew PCBs

maybe mineral oil.  thats not so volatile.

--- In Homebrew_PCBs@yahoogroups.com, "Steve" <alienrelics@y...> 
wrote:
> --- In Homebrew_PCBs@yahoogroups.com, "Phil" <phil1960us@y...> 
wrote:
> > It seems there are two bondings going on here:  toner to paper 
and 
> > toner to board.  The goal is to increase the ratio of bonding to 
the 
> > board vs bonding to the paper so the paper will release.  Of 
course 
> > there needs to be a minimum level of bonding to the board.  
coated 
> > paper works because the toner only bonds to the board-side layer 
and 
> > soaking causes the layers to seperate.
> > 
> > The starch method of decreasing paper bonding is very promising 
but 
> > I've not been able to get smooth enough paper to feed cleanly.  
My 
> > best effort got creases and spacial distortion of the transfer 
> > pattern.  I'm skeptical of this working well for 8 mil traces and 
> > tqfp packages.  I've got some 90 lb paper that might maintain its 
> > integrity during starch treatment and will give it a try.  There 
may 
> > be other products that don't wet the paper but decrease the paper-
> > toner bonding. a very thin coating of a light oil (wd40 springs 
to 
> > mind) might do it.
> 
> Yes, as has been covered here in depth, paper contraction due to the
> heat of a laser printer/copier causes problems. I'd imagine a sheet 
of
> paper wetted and not sufficiently dried is going to be worse.
> 
> I think your analysis of bonding is correct.
> 
> As for WD-40, speaking as an electronics tech: Don't do it! WD-40 
and
> electronics do -not- mix. WD-40 is -not- an oil. It's volatile, 
which
> means heat is going to cause it to evaporate anyway. It's main use 
is
> as a water displacer. My father destroyed the hinges on a truck of
> mine, because unknown to me he was spraying all the hinges on my 
truck
> with WD-40 every time I visited. I couldn't figure out why my doors
> kept squeeking and sticking, I'd grease them, and in a short time
> they'd stick again. He'd hosed out all the grease with WD-40 and
> within a short time all the WD-40 had evaporated, leaving nothing 
but
> metal to metal contact with some dust thrown in.
> 
> I suspect coatings are the answer. I tried inkjet transparencies, on
> the theory that the coating on the plastic is water soluble and so
> would easily let go of the toner when soaked. I was right, the
> transparency got slimy when wet and let go easily. The problem was I
> could not get water all the way under the plastic and the toner 
stuck
> better to dry inkjet transparency than it did to copper.
> 
> And as has been pointed out here, the plastic caused the traces to 
all
> mash out.
> 
> Steve