Re: Printed Circuit Boards.

Dan Mauch wrote:

> From: "Dan Mauch" <dmauch@...>
>
> I checked out your web site. You are doing some really interesting things.
> I noticed that you are making printed circuit boards. I have been using the
> Datak positive PC boards for years using a low cost vacccum IR exposure
> system.
> Until recently I was using Dancam to take the excellon drill files and I
> have a program that optimizes and converts the excellon file to tool path
> for Dancam. Alas, the tool path files are not compatible with G code
> interpreters. How are you converting your artwork to drill your PC boards.

I generate plot files and drill files from PCB CAD software. I used to use
Accel's Tango, but I'm using Protel's Adv Pcb for windows, and using
Protel 98 at work. Each has pluses and minuses. But, I can't imagine
designing complex boards on a mechanical CAD system. In fact, both
the 'Gerber' files for photoplots, and the 'Excellon' drill files ARE 'G-code'!
Yes, they are ALL variants of RS-274D! It really isn't that hard to write
converter programs that chop the commands into pieces and make the
changes necessary to go from one format to the other. Both the excellon
and Gerber formats are fixed point, where the decimal point is not shown.
Some of these are leading zero suppressed, some are trailing-zero
suppressed. That is the biggest difference. Also, the drill file just has
to name a position and a hole is drilled there, as it sets a canned cycle
and G00 positioning mode.

As for PC boards, I got a steal on a dry film laminator, so I now coat my
own boards with DuPont Riston film resist. It works VERY well.
I don't know of any other system that works anywhere near as well
as this stuff. I used to buy my boards pre-coated from Kepro with this
resist.

I hadn't thought about making my 'Excellon' drill file to RS-274D
public, but I will check to make sure there aren't any annoying
bugs that require editing the output file by hand, and put it on my
web site. It has some rather tricky features, such as you set the
machine so that with the drill point just touching the top of the
board, that is Z=0.0. Then, it computes the correct plunge to
make the specified size drill's flank come completely through the
bottom of the board. So, it automatically computes the length
of the drill's point.

Jon