A lot of OEM teams do not get into trouble because the board design is impossible to build.
They get into trouble because the project changes stage, but the assumptions do not.
That is the real issue behind prototype PCB assembly vs. low-volume production.
A prototype build is supposed to help the team learn quickly.
A low-volume run is supposed to help the team execute more cleanly.
Once a project moves toward a pilot run, the pressure shifts:
— the BOM has to support more than a few sample units
— the test method has to scale beyond bench validation
— revision control has to tighten up
— sourcing workarounds that were acceptable earlier may stop working
That is why quantity alone is a weak way to define the stage.
We put together a practical article on what OEM buyers should separate early, and where the transition usually breaks down.
Read it here:
https://www.pcba-china.com/info/prototype-pcb-assembly-vs-low-volume-producti-103463953.html