On Mon, 11 May 1998 06:13:09 -0400, you wrote:

>I use a similar arangement with two tubes, but they are about 8 inches from
>the board, and exposure time is about 5-6 minutes.
This time is about right for various laminates and UV units
>The concentration of the sodium hydroxide is also quite important...
>I have found that about 5 grams in half a litre of water is about right.
>You'll just have to experiment a bit to see what suites your equipment.
Forget sodium hydroxide - it's utterly dreadful stuff for developing
PCBs - apart from it's causticity, it's very sensitive to both
temperature and concentration, and  made-up solution doesn't last
long.

I use a silicate based developer from Mega electronics (UK) - it comes
as a liquid concentrate. I normally make it up stronger than they
recommend (4 to 5 parts water to 1 part developer instead of 9:1) -
boards develop very cleanly in about 5 seconds, but most importantly,
it is VERY HARD to over-develop (i.e. strip) - you can leave a PCB in
'5 second' strength solution for as minute with no visible damage, so
variations in concentration/temp/different resists are very unlikely
to over-develop a PCB. Made-up solution lasts until it 'wears out' -
i.e. indefinite shelf life, and you can then just top up with
concentrate.
Mega electronics are on (+44)1233 893900, fax 893894 I don't know if
they have any outlets outside the UK. They do everything you'll ever
need for PCB making Order code for 1 litre concentrate is 600-010,
cost UKP 9.50 (96/7 catalogue)- this will last the avarage hobbyist a
lifetime.
Also available from Rapid Electronics(+44)206 751166 fax 751188 Email
sales@rapidelec.co.uk, order code  34-0790

For resist stripping I use methanol - drip a thin film onto the PCB,
wait 10 seconds and wipe off with a paper towel. 
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