Chris, I have not tried an waffle iron, but I got a 1 inch thick piece
of steel (4x5x1 inch) and lapped it to make a very flat surface,
attached a thermo couple to it. Using a hot plate to heat the iron block
to to the target temperature then placing this on my PCB/toner image
sandwich and clamping it with a toggle clamp with about 400 pounds of
pressure for about 1 minute (20 pounds per square inch). This gives me
consistent results.
The target temperature is established for the toner formulation your
printer uses. This involves taking an image on a piece of paper and
while monitoring the temp of the hot plate, looking at the toner with a
magnifier and using a sharp pointed probe and noting the softening temp
and the melting temp (my toner melts at about 320 degrees F) The melting
temp is when the toner becomes glossy (shiny). The pressure and temp
combination will determine the amount of image spreading that will occur
. On small pitch traces you may adjust the temp/pressure/time
combination for best results. For very fine pitches, I use a temp of
about 280 degrees (this will just tack the image to the copper) then I
take this tacked PCB/toner/paper sandwich and place it on the hot plate
and raise it to the toner melting point (without pressure) ... this will
cause good adhesion of the toner to the copper with minimum image spreading.
Jim KI6MZ
Chris Trask wrote:
> I'm very much interested in trying this laser toner transfer method for
> homebrewing single-sided PC boards, and the thought came to me that perhaps
> an electric waffle iron would be a more practical alternative than using a
> clothes iron. With the PC board material and the paper sandwiched between a
> couple of pieces of aluminum or copper plate, the heat and pressure would be
> more uniform and it would become a matter of applying the pressure for a
> suitable amount of time.
>
> But without any strawberries or blueberries. :{b
>
> Has anyone ever tried this approach?
>
> Chris
>
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