Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

----- Original Message -----
From: "patroclus04" <patroclus04@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, April 07, 2006 2:32 PM
Subject: [Homebrew_PCBs] Re: Will this work? (my first photo-resist PCB)


>
>
> Here's what I will be using.
>
> http://img218.imageshack.us/img218/4043/box19ks.jpg
>
> it is not finished yet, but still. I can't change the distance between
> tubes and glass once finished, so I'll have a try.
> the two tubes will be separated a about 2 cm from each other, and both
> of them at 7-8 cm from the PCB. Each one is 6W, so maybe they are not
> too close.. I hope! :)

The distance is a compromise, you need them close enough to get a short
exposure and far enough away to get some collimation effect.

Mine is made from three pieces of MDF (fibreboard) strengthened in the
corners with 2 cm square wood and two lengths of wood to support the glass
above the tubes,which are mounted on the base like you have done. I have
enough space to add a third tube.

>
> On the other hand, I will put a reflecting surface below the tubes,
> but I did not plan to close the sides of the "box". As it is quite
> close, I hope no reflector is needed, as I find no easy way of adding
> them.
> I'll try 5 minutes, then 8 minutes, with 2 different little boards,
> and see which one comes out better.
>
> I will be using metasilicate (I hope this is how it's called in
> English) instead of NaOH for developing. Do you guys know if I can use
> the solution several times, or have to throw away each time??
> About 2 minutes for developing would be a good starting point??

You should see the resist coming off, as it is coloured with a dye. Just
leave it a little longer than it takes for all the dye to disappear.

Leon


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