I worked with different Electronics firm for a decade. Hard Disk Mfg, Printed Circuit Board Mfg., PCB Assembly, and I.C. Mfg.
All I know is they are all strict when it comes to quality.
We made ACER mother board and they are one of the hardest board to inspect. So as Nokia 3310 PCB board. I remember, Nokia is sending back the board to us if they found even one defect in their random inspection.
