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

Use thicker glass and let the PCB deform to lay flat against it. The force
of the vacuum (air-pressure) is very large over the big area of the PCB.

Bertho



From: Jeff Heiss Sent: Monday, January 07, 2013 01:46



I experimented with a ziplock bag and a vacuum pump. The transparency is
held to the board very very well. Much better than glass can ever do.
However, I found a drawback and that is the plastic forms imperfections and
scratches from fingernails, stretching and pulling to get wrinkles out
during vacuum, and around the transparency and copper clad edges.

I question, as I have not tested, if these imperfections can cause diffusion
of the light as it passes through and decrease results especially if the
imperfections are over a thin trace or spacing between traces. I tried
blanket storage bags, same problem. My conclusion is that very thin glass
like microscope cover slide glass is the ideal material because it is thin
enough to deform over the copper clad. I searched for glass as thin as
cover slide glass but I could not find a place who sells it. Maybe
something better than ziplock bag plastic can be used too that I am not
aware of.

Jeff





[Non-text portions of this message have been removed]