[sdiy] PCB making: how to get a transparent foil with real black lines?

[Michael Schulze]

I'm using plain old laser printer with regular transparency film.  Then I
expose a Datak pre-sensitized POSITIVE board 6" under a pair of 40W 4 foot
flourescent bulbs for 8 minutes (as the instructions recommend).  Develop
using their process and then etch and tin.

I'm using a positive board, so I don't need to get clean huge blocks of
black on the film.

I know this is very unsophisticated compared to what you guys do - but I've
done a bunch of boards now and they all worked perfectly...

http://www.philmore-datak.com/Positive%20process.htm

> From: Joerg Schaaf <webmaster at joergschaaf.de>
> Reply-To: Joerg Schaaf <webmaster at joergschaaf.de>
> Date: Wed, 5 Feb 2003 19:05:00 +0100
> To: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] PCB making: how to get a transparent foil with real black
> lines?
> 
> Hi,
> 
> I tried several inkjet Transparancy Films with my Deskjet 815C. Only one
> type give me good results - but I never checked those from HP.
> 
> I am using now CG 3460 from 3M.
> 
> I always dry the film after printing the first time and print it again after
> 20 minutes or so. I never
> belived that this can work but it really does.
> 
> After that everything depends on the time you are UV lighting it. I measured
> the time with one test PCB.
> The wrong time can destroy all your efforts. When everything is made carefully
> this techniques gives
> excellent results.
> 
> Cheers,
> 
> Joerg 
> 
>> I'm considering to buy an etching machine as well as UV light source.
>> It's a bundle, some saving.
>> I remember that 20 years ago, when I made my first PCBs,
>> the transparent foil was the issue. Or really: the black
>> areas on it. Because I couldn't manage to make them really
>> black, so there was some light comming through and this made the photo
>> process very instable.
> 
>> Now, 20 years later there are things like ink-jet printers,
>> or laser printers, but my experiment showed that at least the HP870
>> ink-jet couldn't make really black lines. So much for that.
> 
> 
>> Is there someone out there how can propose a better method
>> to get a layout on film?
> 
> 
>> You may ask "why not using a comercial service?".
>> Well, I think they take EUR 40 - 50 for a single sided,
>> 160x100 mm^2 PCB, that's about 4 times what the materials
>> cost! The PCBs would in this case determine system cost.
> 
>> m.c.
> 
> 
>