Comment by cowlevel
3 hours ago
A lot of PCBs will have one or two manual steps but they really try to minimise it. I think anything through-hole is still manual? They can be wave-soldered, but aligning them to the holes is a problem. Surface-mount components (no holes) can be placed and soldered by a fully automated process that self-aligns them to the solder pads.
Through-hole can be done fully automated, for a decent chunk of the parts. The problem is that the automation is quite a bit more involved to set up, and might even need adjustments to the board design to work smoothly. No problem for mass manufacturing, but for small prototype runs it is usually cheaper and faster to do it manually.