Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, Dylan Smith <dyls@...> wrote:
>
> On Mon, 18 Feb 2008, Leslie Newell wrote:
> 
> > That one has occurred to me before. I even got as far as 
disassembling
> > an old black and white laptop to investigate. The biggest problem 
I can
> > see is the thickness of the glass. Unless you have extremely good
> > collimation of the light you will get severe undercutting.
> 
> I doubt it would work - the LCD would expose a grid onto your light
> sensitive material (look at your LCD monitor closely - it's a grid 
of
> pixels - positive exposure, you'd get tracks composed of very small
> squares).
> 
> It would only work with diffuse, very un-collimated light (to avoid 
just
> getting a grid pattern), which would mean you'd only be able to use 
it for
> very large features.
>

I wondered about that as well, however in their efforts to make every 
thing thin and light, the glass screens are getting very thin. If you 
had a UV source that gave you reasonably good collimation it might 
work. 

You might be right about the pixilation problem, however, even the 
ink jet and laser printers have that problem. Many times that problem 
goes away because when you iron or laminate the paper to the boards 
the toner spreads out a little. Perhaps the light spreading out a 
little from the thickness of the glass will act the same.

I have a small TV screen I think I will dissasemble and try it on, is 
there any one willing to sacrifice a 4" x 4" sensitised board? I have 
the UV LED source, but no sensitized boards.