These days, it is hard to imagine electronics without printed circuit boards. They are literally in everything. While making PCBs at home used to be a chore, these days, you design on a computer, click a button, and they show up in the mail. But if you go back far enough, there were no PC boards. Where did they come from? That’s the question posed by [Steven Leibson] who did some investigating into the topic.

There were many false starts at building things like PCBs using wires glued to substrates or conductive inks.  However, it wasn’t until World War II that mass production of PC boards became common. In particular, they were the perfect solution for proximity fuzes in artillery shells.

The environment for these fuzes is harsh. You literally fire them out of a cannon, and they can feel up to 20,000 Gs of acceleration. That will turn most electronic circuits into mush.

The answer was to print silver-bearing ink on a ceramic substrate. These boards contained tubes, which also needed special care. Two PCBs would often have components mounted vertically in a “cordwood” configuration.

From there, of course, things progressed rapidly. We’ve actually looked at the proximity fuze before. Not to mention cordwood.