Homebrew PCBs

Hi
I have given up on TT, so I am gonna try photo
method. How do do the artwork(photo mask)?
By that I mean what sort of transparency, printer etc?
Jeri 
 
 
-----Original Message-----
From: bertd.geo@...
To: Homebrew_PCBs@yahoogroups.com
Sent: Fri, 2 Feb 2007 9:24 AM
Subject: [Homebrew_PCBs] Re: Photo exposure


--- In Homebrew_PCBs@yahoogroups.com, Lez <lez.briddon@...> wrote:
>
> Ok I have had enough tonight of TT
> 
> 
> I need to get 10 little 2 inch * 2 1/2 inch boards done. (only holds a
> pic and some transistors)
> 
> I can buy the developer for £1.20, I can get a 8*4 board for £1.20, so
> for £3.60 I can get everything, except a source of UV..........
> 
> I have heard that outside in sunlight can work, any truth in this?
> anyone else do this?
> 
> I have never done UV before, so have no idea on where to go with
> exposure times etc.
> 
> I happen to have a 9w UV light on the garden pond to kill algae, can
> that be used (badly!)
> 
> 
> 
> 
> -- 
> 
> Lez
>

Hi Lez,
I used to do photo all the time. It's easy once you get the times
down. I used the positve board stock as the process is easier and the
results were excellent. Sunlight is a fairly poor source but cvan be
used. First boards I did were on an overhead projector. I want to
think for about 8 minutes (maybe 10, but I think the 10's were a
little overdone). Any halogen buld is actually a good source of UV so
you could probably expose them under one of those 300w halogen
worklights (just make sue there is no UV coating on the glass).

My actual setup after that was a single blacklight bulb inside of a
curved reflective cover. This woked great & exposure time was only a
couple of minutes. My understanding is the blacklight flourescents are
ideal for pcbs. There coated to emit in the UV region. I also heard
the germ killer lights are no good, Wavelength is to short for pcb.

For the pcb setup I had a piece of plywood and a small sheet of glass
(from a picture frame). Lay the board on the plywood, the artwork on
the board, and the glass over the artwork to keep it pressed down
tight. Under the uv lamp for just a couple of minutes and good to go.

New setup is with 2 15w uv tubes (the smaller ones, 18" T12 I think is
what they are ... I have to check). Going to mount these into a nice
case and set up for photo again. I have a few TT tricks from here I
want to try too but the paper scrubbing one is not my favorite idea of
fun and laminators are out of the picture for me (only have room for
so much stuff).

I'll post when I get some results. Bert


 
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