Homebrew PCBs

Erik Knise <elknise@...> writes:
> What are the advantages and disadvantages of uv film verses toner
> transfer?

I've found that I can do much smaller traces with UV (5 mil vs 8 for
TT) and the results are more reliable, but the process is more
involved (at least, the first time - there's more "stuff" to buy to
get started).  Plus, you have to have a place to buy the film in small
quantities that isn't hugely expensive.

For TT: You need a good enough laser printer, and paper that will (1)
print cleanly and (2) release cleanly.  You have to be meticulous
about cleaning the board or the toner won't stick.  Small details are
hard to get, and the toner lets pinhole leaks get through.  You need a
solvent to remove the toner after etching.  Lamination requires a hot
(350F) temperature to get good adhesion.

For UV: You need a source for the film, a UV exposure setup, developer
and stripper chemicals (neither is nasty and they're reusable).  You
need an inkjet that can print a solid black reliably, and coated
transparent "paper" on which the ink dries super fast (else the ink
smears before it can dry).  Cleaning the pcb isn't as critical, but
laminating the film is - no dust, no air bubbles.  Lamination requires
a cool (200-240F) temperature to avoid melting the film.

Etching is pretty much the same for either technique.

I haven't tried press-n-peel TT paper yet.  If it performs as
advertised, it would be a much faster way to do thick-trace boards:
laser print on PnP, laminate, peel, etch, strip.  For UV, it's print
(takes a while), laminate film, expose, wait, develop, etch, strip.

UV is easier with two-sided boards, because you can see through the
film to align it with pre-drilled holes.  I have special registration
footprints I add to my boards that print as black crosshairs on a
transparent square, just for alignment.