Re: [CAD_CAM_EDM_DRO] Re: Laser specs ?

Dave Fisher wrote:

>I am sure that there are industrial lasers out there for PCB drilling and
>cutting. I read an article
>about a year ago and seem to remember that one unit could `blast` 80 x .5
>mm holes per second in fibre glass PCB material !
>
>
>

Sure, but you have to understand the process. Laser drilling the
substrate is no
problem, at least power-wise. Getting a clean hole for later plating is
a science
unto itself. And, what they drill in the copper is VERY thin foil, in
almost all cases.
1/10th of an ounce or so thickness, so that would be about .00015"
thick. I think
they put something over the foil to absorb the energy, or they
black-oxide treat
it first. And, what they are doing here is drilling TINY holes for
blind vias. To
isolate traces on a 2-sided PC board, you have to make long cuts that
might work
out to several inches per square inch of board area. Also, a 50
micron-wide slot
for isolation would not make a board you could solder. You'd get bridges
everywhere. So, you need to widen the slot to at least .050" for most
solderers
to be comfortable. Being able to pop tiny holes in ultra-thin foil and
being able
to carve long slots in 1 Oz copper are going to take entirely different
power levels.
A sealed CO2 laser is something reasonable for the home shop. You just
need to
get a lucky break on eBay. You can build a flowing CO2 laser, but it
takes a
lot of work to make a reliable one. I think excimer lasers are totally
out of the range
of the home shop. An old YAG laser might be rebuilt and got running
again by
an experienced or dedicated hobbyist, but the parts are REALLY
expensive, and
that stuff (YAG rods, flash lamps, Q switch) is consumable.

Jon