Re: [CAD_CAM_EDM_DRO] Re: making PC boards

To make pc-boards at home, I just use my laser printer. If you peel the
labels off a sheet of labels, then laser print
your design on to the backing sheet, It will iron onto a copper board. Then
etch and drill. Crude, but it worked for my microstep controllers.

Art

----- Original Message -----
From: "Alan Marconett KM6VV" <KM6VV@...>
To: <CAD_CAM_EDM_DRO@egroups.com>
Sent: Thursday, August 31, 2000 2:40 PM
Subject: [CAD_CAM_EDM_DRO] Re: making PC boards


>
> Jon,
>
> That's quite impressive. Must be for more then a "hobby"! I'd heard
> that the laser printer wasn't exactly scaled. But how do you build a
> laser photoplotter? What are the plots from? I can guess that the
> heart of it is an X-Y positioning system, then several apertures of some
> sort? Also obviously a laser! Do you use Gerber format (which seems
> somewhat related to RS274D?? g-code??)? Do you use protel
> (http://www.protel.com/)? There is a freeware and a commercial
> version. The NC file (holes) from the PCB program is then correct for
> CNC? Do you convert Gerber to CNC to run your photoplotter? That's all
> quite impressive!
>
> Sorry for all the questions, but it's all !!! VERY INTERESTING !!! This
> whole process would ALSO be a good addition to the Tutorial section.
> Thanks again for taking the time to answer questions!
>
> Alan
>
> Jon Elson wrote:
> > Alan Marconett KM6VV wrote:
> >
> > > Do you do double sided boards? Purple (?) sheet "negatives" from a
> > > laser jet? Then etch them? I've seen the CNC-type mechanical board
> > > etches like LPKF, and often thought about writing code to generate CNC
> > >
> > > "g-code" to cut boards on a Sherline mill. Anyone doing something
> > > along
> > > these lines?
> >
> > I do double sides, but without the plated through holes.
> > No, laser printers are not accurate enough to register the two
> > sides together. Any board over 2" square will have serious
> > misregistration, such that holes drilled dead center from
> > one side will completely miss the pads on the other side.
> >
> > I built my own laser photoplotter, which records images directly to
> > red-sensitive
> > silver litho film at 1000 dots/inch. The blacks are totally black,
> > about a log
> > density scale of 5 or so, and the clear is very clear (high contrast).
> > The films match up, over 10" or so, to within a few thousandths.
> > I align the films with a plexi sheet the same thickness as the board
> > between them, and tape to a piece of PC board scrap to hold the
> > alignment. I use boards coated with DuPont Riston dry film resist,
> > and expose in a fluorescent vacuum frame. Development is done
> > with a sodium carbonate solution, leaving a resist that is almost as
> > tough as solder mask. It will take extensive overetching without
> > much damage. The boards are etched in a heated spray etcher.
> >
> > I drill the boards with a mod that mounts on the quill of my Bridgeport.
> >
> > It is a Westwind air bearing drill spindle that now runs at up to
> > 24,000 RPM. (With a better inverter I could go to 80,000 RPM.)
> >
> > I've seen the LPKF machines, they seem to work, and do get rid
> > of the nasty chemical processes, that are also time consuming.
> > But, on the other hand, the etching process develops both sides
> > of the board at the same time, and it takes no longer to make a
> > board that is 10 times more complex.
> >
> > Jon
>
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