There's good printers and crappy printers. Crappy: lasers, many
inkjets. Good: epson stylus colour. I did various comparisons.
The main thing with the epson ones is that the genuine epson
inkjet transparency has a smooth absorbant layer, and the
printout is also smooth.
To test for exposure, expose segments of a pcb in 30s increments,
then develop. Make your exposure time a couple of minutes longer
than the minimum. Crappy printouts are easily over-exposed. With
an epson printout, i expose for 5mins using a small light-box with
4 tubes, but if i forget and expose it for half an hour, i still
get an excellent result (just some tracks get slightly thinner).
johnman9146 wrote:
>
> That kind of misses the point. I am looking to see if anyone knows
> of a suitable etch resist ink, and/or a suitable soldermask ink.
>
> If I do decide to go your way and do the transparancy method with UV
> sensitive photoresist, I have a few questions.
>
> How do I know when I have the proper exposure?
>
> Can you over-expose?
>
> How dark black does the transparancy need to be for this method to be
> effective?
>
> I have access to some pretty sophisticated hardware if I do decide to
> try this method. Items such as a photoplotter, a vacuum backed UV
> table (for exposing printing plates) and more, but it is a hassle to
> go there for all the neat toys.
>
> I don't think there would be any issues with the image size not being
> exactly 100% as it is a professional photoplotter designed to make
> printing plates for magazine reproduction.
>
> Potentially, I may just have to experiment with different inks if
> nobody has any suggestions.
>
> Does anyone print legends on thier prototype boards?
Some labels on the top copper.
> Does anyone use anything to add a soldermask?
>
> Does anyone even use any type of conformal coating?
Sometimes, for water-proofing.
> > Im my opinion you're much better off using photoresist coated
> boards.
> >
> > Print your layouts using the right transparent medium for your
> printer
> > (laser or inkjet) and use that to expose the board under UV. I made
> a
> > suitable lightbox with tubes sold as spare parts for the ready-made
> > unit sold by Maplin. I also use ready-prepared developer and etcher
> > from them and get a great result every time.
> >
> > Cheers
> >
> > Derryck