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

Thanks for the idea of measuring the powder, I hadn't thought of
that way to do it.
Adam wrote:-
"Before worrying about exposure times, try as I said before, and
expose a
piece of PCB in the sun for 20+ minutes, put some black PVC tape on
one
half to block out the light. Then you have guaranteed exposure.
Develope
the PCB and see how it goes."
I live in the uk and at the moment the weather is rain and them some
more rain, so the chance of sun is very slim.

I did however try exposing a peice of board for only 2 mins and
another at 1hr 10 mins but with no image showing on the board before
developing as stated by Stefan:-

"with the boards i used one could see a yellow/green discoloration
if you hold it at an agle against the light."
and Leon
"There should be a faint image visible if the exposure was OK"

So Now I have tried boards without film and with film for the
following times
2,4,5,6,7,8,9,10,11,12,13,14,16,18,20,22,24,26,28,30 and 1hr 10 mins.
I get no colour change what so ever to the board.
So with this in mind I think:-
a/ The problem may be that I am using Phillips TL 8W / 08 F8 T5 /BLB
blacklight tubes and not pcb exposure tubes (which are now back in
stock). Maybe these tubes do not produce the uv required to expose
the board or
b/ the glass is stopping the uv from passing to to the board (this
was salvaged from a
cheap photoframe)
To eliminate the possibility of the uv being stopped by the glass I
secured the film to the board, placed it in the bottom of the
exposure unit under the uv tubes and exposed for 14 mins.

Still get no image , thinking the presensitized board is faulty
allthough it looks the same as some other board I purchased from a
seperate source at a different time.

anybody use this "fotoboard 2" make before (available from maplin in
the uk)

Getting desperate

Tbone