Homebrew PCBs

--- Kamal Shankar <kbshankar2000@...> wrote:

> > do you use a paper towel 'buffer' between the iron
> > and the TT paper back?, up
> > to 4 ply can be very useful.
> 
> Hmm... is using a "buffer" between the iron (set at
> cotton) and TT paper back that important ?
> 
> Tilll today, I just apply the iron directly onto the
> back of the 65gsm glossy paper.
> 
> Will using a "buffer" actually improve anything ?

surely it does, just try yourself when, how and how much. Direct ironing (with
the edge or tip) is sometimes necessary to insure proper application, mostly on
edges or large patches. I, myself, go over all the board with the tip, just in
case...

> 
> Also, will applying too much pressure on the paper
> actually destroy the TT ?

not I am aware of. If you use the buffer you don't risk to squeeze the traces
at all, then be prudent with retouching the critical areas with the tip of the
iron.

 
> I have noticed this leads it tracks falling off as
> easily as if proper heat was not applied.

I see two reasons:
- iron is not hot enough. should be, at least, some 235C (460F). buffer should
yellow in less than 5 minutes.
- improper board prep. scrub the board with that (kitchen) 'abrasive' cream
until towel (not fingers) gets black, top down and then left right. Rinse under
running water and wipe dry with towel. NO FINGERS, please. Board will be shiny
and only very slightly scratched, any dull part is wrong. Sandpapering or deep
scratches are not good, avoid them.

If you have to re-do a TT then remove the failed print with acetone (that
smelly nail polish remover) and RE-SCRUB the board. The heat, water and acetone
residue will stain the copper enough to make it not useable as is.



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