East Vs West (?) preliminary note: this are MY assumptions, and not backed by any direct communication with any of the involved. a few years ago there was a big split between in the arduino team . arduino as a company started when fellows from a design school in italy took wiring (a student theses) and hooked up with a board manufacturer . that allowed them to scale and produce the arduino board. fast forward a few years, and arduino wanted to start producing 4 layer boards, alas, the original partner didn't have the capabilities. see this designboom article for a 2013 visit to their manufacturing partner
https://player.vimeo.com/video/73860282
another trip to a pcb manufacturing facility, this time in USA. by Mrs Blanche.
https://www.youtube.com/watch?v=QBtK-PesGsU&&
and now, a visit to a modern PCB facility in china
https://www.youtube.com/watch?v=ljOoGyCso8s&&
more notes by Bunnie , from his book "*The Hardware Hacker: Adventures in Making and Breaking Hardware”*