Re: TI-H: PCB
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Re: TI-H: PCB
On Fri, 7 Aug 1998, David Knaack wrote:
> >On Fri, 7 Aug 1998, David Knaack wrote:
> >> >press that on top of the positive photoresist-treated board out in
> >> >direct sunlight for about 10 minutes.
> >>
> >> Have you actually used that method? I have read that you could do
> >> it that way, but I also read from someone else that it takes several
> >> hours to harden the mask using sunlight.
> >
> >Yes, I have. I live near Salt Lake City, Utah (USA). I don't know
> exactly
> >what my latitude/longitude is (and therefore how much more/less intense
> >sunlight would be here as compared to wherever you're located),
>
> San Antonio TX, UV content should be pretty much the same.
>
> >but I went out on a bright summer afternoon and propped the thing
> >up so as to face the sun directly. You could buy a small board and
> >cut it into smaller pieces so you could try different exposure
> >times to see what works best where you're located.
>
> Sounds like a winner.
> Does the photoresist change color when it has been exposed so you
> see the mask? That would be a handy way of knowing when you had
> exposed it enough.
The color does not change until the board is put in the developer. This
causes the softened stuff to come off (leaving bare copper plating) and
makes the traces turn dark (if I remember correctly). I think it was a
greenish color, like a green CD-R disc, before being exposed.
> Those blacklight light tubes you see at Spencers and other shops
> are UV, are they the right wavelength to harden the photoresist?
I'm not sure. I initially started with the negative-resist process, found
that I couldn't get it to work, and called the manufacturer. They referred
me to some guy in New Mexico (a rep or something) who basically told me
that the negative process was too much work and so he'd just send me some
free positive-resist boards and chemicals instead of getting the negative
method to work for me. Good customer service, in my opinion. :) He'd
probably be able to answer that question for you better than I can. His
name is Bob Reynolds, and his number was 505-898-2104 last I checked. He
was a consultant or something for the board manufacturer, and called his
business Outside Ideas. I think. Anyway, if you could get ahold of him
he'd probably be able to answer all your questions about that product. Or
maybe you can find specs for pretreated positive-resist boards on the net
someplace.
--
Greg Hill
greg-hill@bigfoot.com
www.comports.com/link
References: