Possible Laser diode application to milling a board was Re: Re: Future Features and other administrivia


KM6VV
 

Hi Harvey,

Harvey White wrote:

So you think it's better to completely coat a board with toner, then burn it off? Does that leave bare copper?
It might, it would also leave a residue. You'd be burning off the
plastic.
I suspected something like that.

I thought the laser toners were some sort of carbon? not plastic (inkjet?)? So one would need a way to evenly cover a board, and fuse it on.
Carbon loaded fusible plastic. Applied as a dust, attracted to the charged areas, fused into a solid (sorta) block by the fuser (heated

roller), and that fuses into the paper.

Toner transfer systems fuse onto something that either dissolves in
water easily (rice paper?) or has a weak adhesion to toner. The toner
melts and fuses to the PC board copper.
(note: with varying degrees of success....)
That's what I'd heard, a lot of experimenting to get the process just right.

We're back to the functions commonly done by a laser printer! Electrostatic charge to attract the toner powder, a fuser, and THEN a laser, this time to burn off toner rather then dissipate the charge on the toner drum.
Big problem with a laser printer is how to make the charge distribute
evenly across the conductive board, and not at the edges, where it
wants to be.

My understanding about current laser systems is that the drum is an
assemblage of crystals, which conduct poorly across the surface, and
well *to* the surface of the drum. Hence a small area can hold a
charge. If we print from a drum onto copper, this might work. If we
print the toner onto the copper, I'll be it won't. Period.


OK, a little different. I wonder it a copper plate can take a charge like the selenium (?) drum in the laser printer?
See above, I think the answer is an unqualified "NO".

at least, not in a useful manner.

I'd have to go along with that conclusion. A charge acts much different on insulating surface then on a conducting surface, as you've indicated. We need to apply a resist that can be cleanly burned off some other way.

What drive do these diodes need? We'd also need on/off control via program. Humm, almost like a spindle control.
Current regulation like you wouldn't believe for a laser diode. My
understanding is that they will self destruct with too much current,
and not lase with too little.

Most applications I know of suggest that you use the supplied driver
chips/board.

Harvey
I'm totally unfamiliar with Laser diodes. Perhaps Kevin can "shed some light" on this subject! Sorry, couldn't resist! Oops! did it again.

Alan KM6VV