I used to work in the design division of an electromedical company in the early 70's. We had 4 engineers and 3 techs. I was a tech. One of my jobs there was to layout and print prototype pcb boards from the schematics. Most were 2 sided. I would lay the board out on a light table at 4x the finished size. Take them to a guy who would print them at .25 the original size. Then use the negatives to print on sensitized pcbs. Develop them and etch them with ferric chloride. Once done with that I would drill the boards and mount the components. Once done we would test them and occasionally make a change. Not once did I ever see anyone use a pcb board in the way that I make them now.
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73
Dave
_Dave_ AD0B