Homebrew_PCBs

ghidera2000 wrote:

> Just attempted my first photofabrication and it failed at the
> developing stage. Within 30 seconds of immersion the board was
> completely devoid of resist...
>
> Here's what I did (all M.G. Chemicals supplies)
>
> -Printed out my circuit onto a transparency (IBM Laser
> Transparencies, 24L5041) using a Samsung ML-1210 laser printer.
> -Poured two litres of hot tap water into a tray.
> -Poured 200ml of Developer into the tray of water (10:1 as per
> instructions).

The problem is you used *hot* water. Make sure it's warmer than 20deg
or it'll be slow. Make sure it's less than 30deg or it'll peel.
25deg is ideal.

> -Set up the UV light using the supplied stands (about 5-6" high).
> -Placed the sensitized board blue side up. Positioned my
> transparency (ink side toward the board) and placed the plexi weight
> on top.
> - Waited 5 minutes then turned out the light (actually probably more
> like 5.5 minutes).

Laser printouts can be pretty crappy. Can you see light thru the
larger black areas? Do some exposure test strips in 30s increments
starting from 1min. Consider getting a decent inkjet.

> - Immediately put the board into the developer solution. I used the
> supplies foam brush to agitate the water (didn't come within 1/2" of
> the board itself, just slowly waved it back and forth at the
> surface). Solution was about 95-100F by this time.
> - About 5 seconds in I could see my traces through the clouds of
> black ink. As the black ink cleared I could see traces starting to
> fade out too. This is about 15 seconds into the process. I realized
> the board was already toast so I waited to see how long it would
> take to completely erase the resist - was about 30 seconds.
>
> The instructions say it should take about 2 minutes to develop the
> board. This was a LOT faster... I'm thinking perhaps the developer
> was too strong? What about temperature? Should I just use developer
> at room temperature instead - give myself more "OOOOP" time?
>
> I guess its also possible that this laser's toner isn't UV opaque
> but, the speed at which the board completely blanked and the fact
> that I saw traces - even for a short time, makes me think its a
> developer problem.