This video by designboom gives us a glimpse into the making of an Arduino PCB. Arduino boards are still produced in Italy! You can see an interesting picture (last one at the bottom) which shows an arduino in a programming and test fixture. I am quite surprised to see that they are programmed individually, I would have though there might have been either a large program and test system which would have done a panel at a time or an automated line where they were just fed in one end and came out the other end with a pass or fail indication.
“who would ever imagine that global cultural and economic revolution would spring from the tranquil fields of piedmont, italy, in tiny towns nestled against the stunning backdrop of the alps? but that’s exactly where arduino, the system of microcontrollers revolutionzing the maker movement and pioneering the concept of opensource hardware, was born in 2005 and continues to make its home today.”