On 08/30/2015 03:04 PM, Chuck Guzis wrote:
PCB design was also a specialty, what with mylar film,
tape, white-out and India ink and, of course, an X-acto
knife. The best people at this seemed to be from the Far
East. Done probably at 4X scale, then reduced for
production.
Yup, back in the 70's I did a bunch of PCB design using
mylar and black crepe tape, and pre-made donuts and IC pads.
UGH!!! I still have a bunch of those sitting in folders. I
made my own reduction camera to bring the artwork down to
1:1 size.
Then, in 1976 or so, I got my first CAD system, and printed
everything out on plotters with India ink and Rapidograph
pens on frosted Mylar. If the pen didn't clog up or run dry
before the print was finished, it worked pretty well, and
there were Litho houses that mostly did ad copy that would
do the reduction for a couple $.
I hacked a fiber optic light pen onto a Calcomp plotter and
made some artwork directly onto film, and then in 1996 I
built a laser photoplotter that cranks out 1000x1000 DPI
images on red-sensitive film at 0.6 inches/minute. It can
do up to 20 x 24" films, but I've never gone over about one
foot square. The trick is, it has to be VERY accurate to
line up with existing PC boards. I mostly use it to make
solder paste stencils, now, but originally made it for PC
board master artwork.
Jon
