Homebrew PCBs

agscal -AGSCalabrese wrote:
> The copper just does not get hot enough I would guess.
> 
> 
> 
> On Nov 11, 2007, at 11:20 AM, DJ Delorie wrote:
> 
> 
> Got some 8 mil thick clad, tried sending it through an old Laserjet 4.
> The panel went through OK, but the toner just didn't stick to it. I
> saw a faint image of the board on the copper, and a second print on
> paper had two copies of the board on it.
> 
> Sigh.
> 
> OTOH the lj4 seems to be able to image 3.33 mil lines reasonably well,
> and 5 mil lines look nice and crisp. Maybe it will work better for TT
> than the 2550N, assuming I can get it onto the board without mangling
> the toner.
> 
The basic theoretical reason that laser drum straight to copper circuit 
board won't work is that it(the copper surface) provides a short circuit 
onto the drum surface which is an insulator that has a few thousand 
volts applied to it to hold the toner. Stefan's idea that a pickup 
roller can then be provided is a good one. Next you would then need to 
provide a HT (high tension connection to pick the toner off the pickup 
roller and then onto the copper board and then fuse it on with heat.

Here is a rather poor explanation of the laser process.

http://www.everything2.com/index.pl?node_id=111795

A better explanation is in the book "Xerox - American Samurai" By 
Jacobson, Gary, Hillkirk, John 1986 Macmillan ISBN 0025516000
which details the evolution of the photocopier from wet process's to the 
laser printer.

regards Andrew