What is so difficult about printing the pattern onto clear film
(overhead transparencies) and make a contact print exposure of the resist?
It would be FAR simpler and cheapper I would think. (and faster if you need multiple
boards).
The sun is a free source of sufficient power UV light.

Robert


Neil Baylis wrote:

>>If photoresist boards can be "influenced" by these high powered lasers then it could be a cheapish way of "printing" directly onto PCBs.
>>
>>Thoughts are to either have a rotary indexed table or maybe reverse engineer a cheap laser printer and pass the board through using the printer optics to raster print the image onto the board.
>>
>>Anyone know what happens to photoresist under a moderate power laser beam ?
>>
> 
> 
> The laser from a DVD burner most likely won't have any effect on the
> resist. It's wavelength is about 650 nm, whereas the resist is
> sensitive to UV. You may have luck if you were to use the laser from a
> Blu-Ray burner, but that will set you back many hundreds of dollars.
> 
> The guts from a laser printer won't cut it either, because they use a
> much lower power laser, and it's 780 nm, which is even further from
> the seisitivity of the PCB resist. In addition, the spot from the
> laser printer moves very fast across the surface, so will never stay
> in one place long enough to affect the resist, unless you were to
> write the same scan line many thousands of times before stepping on.
> It might be possible to istall the laser from a Blu-ray burner into a
> laser printer.. but then all the optics would be wrong and the beam
> would need to be refocussed and realigned somehow.
> 
> I think a more promising route is to use a much higher powered laser,
> and find a positive acting resist that hardens with heat, or use a
> resist that the laser selectively ablates. I'm building such a system
> at the moment, using a CO2 laser, but it won't be functional for a few
> more months.
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist