On 11-May-98, Clewer,Brian wrote:
>Hi all,

>I made a UV exposure unit for producing PCB's at the weekend.  It
>consists of 2   8watt tubes inside an old PC case.  I have a photo
>sensitive PCB held behind a glass plate about 1 and a half to two inches
>above the tubes.  The tubes are brand new and are replacements for the
>normal unit you can buy in the shops.

>My question is 'how long would be a reasonable time for exposure' ,
>because I tried this out last night with an exposure time of one minute
>and when I was developing it in sodium hydroxide, it appeared to work at
>first but it then took all the photo sensitive layer off.

>Any help is appreciated,

>Thanks,
>Brian.

I have built something similar and I normally use about 5-6 mins and develop
untill photo layer goes except where tracks are.


Steve