I am working on a Quality Assurance procedure document for PCB integrator. I did some research on the quality standards followed by different companies. But what I could not find was a general and basic procedure by which I (as a client) can evaluate how my PCB manufacturer and integrator have fabricated my PCB post fabrication. P.S. These procedures are just for Visual Inspection. I have a separate procedure for Factory Acceptance Test (FAT) where I check the PCB by applying voltage, uploading code and other procedure.
NASA used to require high-rel PCBs to have a test-frisket off to the side, with vias and traces at tight-spacings.
After the PCB was fabbed, the frisket was removed and SLICED OPEN thru the vias, and the vias' internal plating was examined for proper thickness. Also the connection between vias plating and the laminated foils were scoped for integrity.
For ultimate reliability, JPL required tiny "Z" wires soldered into each via. Only 2-layer PCBs were used, and only tiny amounts of solder were used for weight control. With such redundant methods, satellites last for 50+ years.