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Subject: Re: [Homebrew_PCBs] Re: Any info about this technique?

From: Dan Pickard <dlpwebmail@...>
Date: 2006-11-16

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



Chris,

I also have been working with dykem on circuit boards. I had limited success with a Roland XY plotter and a awl for a pen. I found that it was very hard to isolate all the IC pins. The plotter didn't have enough pressure or speed to get a good scratch.

I've also been working with a co-worker that just bought an Epilog laser engraver for $30K. I asked him if he could cut the copper from circuit boards for me. To make along story short it didn't work. Not enough power (60W) and warped boards. I never thought of cutting dykem from the board with his laser though. I'll pass this info on to him and see if we can try it again. You can probably find a laser engraving shop in your location. They charge by laser cutting time and if you should be able to cut fast with little power, the fee should be minimal.

Dan


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