On Fri, 10 May 2002, Donny Tan wrote:

>Has anybody try doing the double layer PCB printing using self made
>exposure box and self made developer and etching tank?

Yes. For protos.

>What is the most optimized setup in terms of light source intensity,
>exposure time and developer concentration?

250W high pressure Hg arc lamp at 40cm, reduce distance acc. inverse
square law for lower power lamps, 5 minutes exposure on timer, 4 grams of
NaOH/liter as per photoresist leaflet, can be upped to 8 grams carefully.
Work time in developer is 3 minutes with some mixing at room temp. I do
25mil tracks all the time like this. I use a homemade exposure frame (2
sided glass with industrial textile tape hinges and edges) and taped (to
each other) top/bottom board films to form a pocket into which the PCB is
inserted. I do not have registration problems at up to 20cm x 15cm boards
even for SMD.

This is not 'the most optimized' setup. The most optimized setup is the
one that works best for you.

>Is the printer slide suitable?

Yes.

>What type of water (tap water/ DI water/ distilled water/ battery
>water=85)do you recommend to mixed with the developer?

Tap water for NaOH, tap water for 6% HNO3 by vol., follow instructions
exactly for perchlorate.

hope this helps,

Peter

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