Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

With all the discussion about different ways to produce circuit boards and a lot of list members competent with CAD/CAM and positioning tables I'm surprised there isn't more discussion about the old Multiwire method of producing small numbers of one-off circuit boards. The process was truly simple. They just applied some very thick epoxy to a bare board surface and ran magnet wire all over the place from one hole to the next. The wires would cross over each other but the insulation prevented a short. After the epoxy hardened you drilled the holes, exposing the bare ends of the wire, the holes were plated to achieve conductivity (but there should be some other way to get the wires connected to the component leads), and the board was done.

These machines were very rare because they were quite slow. They laid wire down at a rate of about 4' per minute. They were usually found in research labs that only needed 1 or 2 boards of a given design. Only one shop in Texas had more than a couple of these meachines. They used them because of the better control of electrical characteristics of the finished boards which was needed when working at very high analog frequencies.

A quick look on the web indicates that all the machines have migrated to India.

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