PCB vs wirewrap, was Re: SBC6120 (a build-it-yourself PDP-8 clone) grammer checked

Don Y dgy at DakotaCom.Net
Tue Jun 6 12:16:59 CDT 2006

Brent Hilpert wrote:
> There was another technique for making circuit boards in the 70s: a
> programmed/automated machine moved over the initially bare board and laid down
> a fine wire from a spool to form the circuits. I think the wire stuck to the

Yes.  *Very* fine wire.  It "looked" like magnet wire.
It was really cool because the wires would crossover each other
at will (insulated with lacquer?).  So, you had to learn that
"touching" wasn';t synonomous with "shorted".

I think there were still "conventional" power planes on the interior

> board initially and the board was later lacquered or coated with something to
> seal/hold the wires better. I forgot how the wire traces were terminated
> around IC pin locations, probably a pressure weld.
> I think the economics were such that it was too slow for large production
> runs, but was suitable for prototypes and small production runs of larger,
> more-complex boards. Last example I saw was a disk-controller for a TI-990
> mini circa 1980.

I saw it used in a little (explosion proof!) ATE controller for
flight line diagnostics (military).  Perfect application as you
had very dense/complex boards and very limited "production".

> Anybody remember the name for the technique?

Nope.  But I will see if I have any written notes on it...

More information about the cctech mailing list