“All the histories seemed incomplete and some were clearly inaccurate,” writes engineer Steve Leibson of his efforts to find the ‘origin story’ of the printed circuit board (PCB). So for lack of a proper history, he wrote one himself. Leibson reveals the PCB can be traced to the proximity fuse, a post-WW2 device for making explosive munitions more accurate, and that in 1947, the U.S. Army Signal Corps developed an “auto-sembly” technique to mass produce electronic boards (image: tube-based circuit boards, 1949).