Test escape
Beginner
A broken chip that passes the factory test by mistake and gets shipped to a customer.
Novice
A defective chip that passes manufacturing test and ships. Escapes come back as customer returns. The opposite mistake, failing a chip that was actually good, is called yield loss.
Expert
Caused by defects no fault model describes, gaps in coverage, timing defects a slow test can’t see, and failures that appear only at certain voltages or temperatures. Escapes set the shipped defect level; overkill (failing good parts) costs yield.