Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, DJ Delorie <dj@...> wrote:
>
> 
> In cases like this, you really should consider buying a transmission
> step wedge.  I got a stouffer 21-step wedge for $7 plus s&h and it
> REALLY tells you how well (and accurately) your process is.  For
> example, my inkjet gives me an 8-step range, but my laser printer only
> gives a 3-step range.  Even the worst inkjet film I can print is going
> to be better than the laser printer.
> 
> I found that using "standard" software and films won't give you truly
> opaque prints.  I ended up writing my own printer driver just for films,
> and buying Jetstar films (perhaps anything with "ultra fast drying" in
> the name should work, but YMMV).  The specially coated films let me put
> much more ink than standard software would, resulting in a much darker
> film.
>

I didn't mention it before but I did a rudimentary test by covering the board with a credit card and exposing a little bit every minute for 7 minutes (chose that time as I saw a site where someone who made a UV box with LEDs say 7 minutes was the maximum they could go before overexposure)

It seemed that 1-3 minutes or so was underexposed, anything over that was good but had the speckling problem.

I tried putting the printer control panel on darkest. It didn't seem to make any difference. The film is designed for inkjets and appears to have a special coating.

A custom printer-driver sounds great, I don't suppose yours is available and is for Canons?

I wonder though if I somehow could force the printer to print black by mixing the colour cartridge it would be like getting 3 layers of artwork, from the 3 different inks. Not sure how to do that though.