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

Hello to HB_PCB group
I am a new member and this is my first post ... the common thread in the
TT process is difficultly in cleaning the paper residue from the bare
copper after soaking and prior to etching ... the traces I make are
usually 0.015 or larger and spacing is 0.015 or larger and the residue
removal has been the most difficult step ... recently I was talking to a
chemist friend about this problem and he suggested using some enzyme
boosted washing powder (either automatic dishwasher powder or cloths
washing powder) they have enzymes that convert oil to sugar, dirt to
sugar and cellulose to sugar ... the clay coating on the paper I think
is close to dirt and the paper fiber is cellulose ... I used Tide
clothes washing powder (1 tsp to 1 and one half cup of water) at room
temp ... after the initial soaking (in warm water) to remove the bulk
paper and the rubbing of the residue with my thumb to remove as much of
the residue as possible I now soak the PCB in the Tide solution and
after about 5 minutes, almost all the residue in holes and between
traces can be easily scrubbed off with a tooth brush ... an additional
soak may be required for some real stubborn areas ... I now can be
etching 30 minutes after image transfer ... I found the dish washing
powder was too aggressive and would cause small pin holes if the soak
was too long (it works but the timing in more critical ) I would like to
hear from someone that has tried this ... it really seems to work for
me . the toner I use is the toner that comes with my HP1022 laser
printer ... it softens at about 230 degrees F and melts at 310 degrees F
... I heat a 1 inch thick by 4 inches long and 3 inches wide piece of
steel that I have ground flat to about 0.001 inch to about 350 degrees F
... this is placed on top of the cover paper / image paper/blank PCB / 1
inch thick wood stack and clamp it to about 250 pounds per sq inch for 1
to 2 minutes ... the PCB is then put in the first water soak ... the
transfer paper is Impreso Glossy Photo Paper for ink jet printers ... 47
lb ... it is coated on both sides (I buy it at Frys Electronics) ... I
have had good results with the TT process on small boards and with the
enzyme soak to remove the residual paper/clay it is also a fast process ...
Jim KI6MZ