Thank you for the reply, I found it very interesting. As you say part of
the answer is in cleaning or preparing the copper surface but most of my
problems lay with the ink. I got in contact with many ink manufacturers and
we had some rewarding discussions about this application. It basically
boils down to the choice between a solvent based ink or an UV cured ink. The
water solvent based inks I have tried so far, simply wash off in the acid
bath. There can also be a problem with the solvent vaopurising and cloggung
the head. I came to the conclusion that a UV cured ink may be a possible all
round solution. These are actually resin based and offer a much more durable
printed image. UV inks are available that will cure in a fraction of a
second. So it might be possible to mount a fibre bundle from a UV light
source to just behind the print nozzles as a low mass light cure source.
Taking the idea one step further, it would also be possible to
print, graphics, flux as well as acid resist direct onto the board. This
leads us onto conductive inks, which already exist. They normally require
special for purpose heads, but seem to work well for most low power
applications. I think for my own purposes a simple A5 flat bed printer,
using UV cured ink would do the trick. Another advantage of UV ink is that
it does not dry in the nozzles as solvent ink does. I have seen applications
where multilayer boards have been produced using UV inks, with an insulating
ink between layers ... and all of this printed on a flexible substrata.
Anyway who says we have to have a purpose substrata since we can print onto
anything!
It is possible to convert the older models of Cannon printers
into flat bed, I have one on the bench at the moment. Thanks again for the
reply. .
John.
----- Original Message -----