There are always plenty of laser diodes available on eBay. I have
enough experience with them to make the laser part work. It involves
getting a laser diode, making a diode driver, and adding a focusing
lens. The electronics are simple, but tricky because the laser diodes
are easily destroyed. The lasers I'm thinking of are IR, 808 nm at 1
to 4 watts continuous power. Such a laser is nowhere near powerful
enough to affect the underlying copper, but will burn through black
paper, electrical tape, etc.
It would also be possible to simply buy an integrated laser module,
complete with optics and drive electronics, but that would be well
over $1000.
Another possibility would be to use a CO2 laser. These are much
larger, and require water cooling. These may be powerful enough to cut
through the copper, but I don't want to go there.. those are quite
dangerous lasers, and I don't want to deal with vaporized copper
fumes. Vaporized dykem or some such thing seems doable.
I guess I'll just have to make a diode laser assembly and experiment
with various lacquers to find one that will resist the etchant, absorb
IR, and not catch fire under the laser.
http://www.roithner-laser.com is a supplier in Austria that has
complete laser modules. There's someone on eBay selling complete CO2
lasers from China at about 30 Watts. These would easily do the job at
high speed, but not for the faint of heart.
Assuming I made that part work, what would be a good XY plotter to
look for? What software do I need to plot out the negative parts (the
parts that need to be removed) instead of the positive parts?
Neil
On 11/16/06, lcdpublishing <lcdpublishing@...> wrote:
>
>
>
>
>
>
> Neil,
>
> This process sounds very interesting using a laser. I had planned to
> try something similar using the machine I am building but a "Scratch
> tool" as opposed to a laser. I always suspected that isolation
> milling would be very dependant on two things:
> 1) a tool that will cut good, without burrs
> 2) a spindle with high enough speed and zero - runout at the tool
>
> To avoid those problems completely, I was planning on using a spring-
> loaded scratch awl type tool. Then, just run the CNC program path
> for the isolation milling to scratch away the resist.
>
> For the resist, I was thinking about using Dykem which is a lacquer
> based product used in machine shops as a layout colorant. It will
> stick to all metals, drys fast, and works very good with
> the "Scratch" removal process as that is what it is designed to do.
> You can purchase it in spray cans, brush-bottles, or little
> dispensers with a pad applicator. I figured I would use the spray
> can version as that should give the most consistant coating.
>
> Now your idea of a laser would take away another mechanical aspect of
> this process which is appealing, but I know enough about lasers and
> myself to know that I will probably hurt myself with one ;-)
>
> Can you tell me where I might find a laser that is suitable for
> this? Even with the risks involved, I would like to consider it.
>
> Chris
>
> --- In Homebrew_PCBs@yahoogroups.com, "Neil Baylis" <neil.baylis@...>
>
> wrote:
> >
> > I don't know what this is called, but I assume there are folks
> making PCBs
> > this way:
> >
> > 1: Coat the copper board with a thin film of lacquer
> > 2: Use a laser to selectively burn away the lacquer leaving bare
> copper
> > 3: Etch
> >
> > Can anyone point me to info about this technique, especially what
> kind of
> > lacquer to use, and an idea of how much laser power would be
> needed. I've
> > noticed that I can get dark materials to smoke with about 100mW of
> laser
> > power. I guess that with the right lacquer, this technique could be
> done
> > with about 1 Watt laser power, which is easy to obtain.
> >
> > Obviously, the laser would have to be mounted on some kind of x/y
> plotter
> > device.
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
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