Memory-module manufacturing method with memory-chip burn-in and full functional testing delayed until module burn-in

Abstract

Reliable memory modules are assembled from partially-tested memory chips that are neither individually burned-in nor fully tested. Instead, individual memory chips are partially tested to screen out gross failures and then assembled into memory modules that are inserted into memory-module burn-in boards and placed into a burn-in oven. The memory modules are stressed during burn-in by high temperatures and applied voltages. After burn-in, the memory modules are removed from the memory-module burn-in boards and extensively tested. Functional tests include many test patterns to test all memory locations in the partially-tested memory chips on the memory modules. Tests are performed at corner conditions such as high temperature and voltage. Infant mortality and single-bit faults are detected by the functional tests after module burn-in. The number of insertions into burn-in boards is reduced by the number of memory chips per module minus one, so handling and test costs are reduced.