Environmental stress screening for a massively parallel vision computer

AISI began experiencing a severe field reliability problem with their computers. There was a single point source of failure in the systems in which they were incorporated. An issue with programmable array logic (PAL) had driven the customer return rate to approximately 45% and caused severe production problems for the ultimate users of the computers. The legacy screening process used by AISI was ineffective at screening out the problems. The limited amount of failure analysis performed was inconclusive at identifying root cause of the failures. A screen was developed based on generic information on technology failure mechanism and circumstantial evidence gathered by AISI. The resultant screening used both temperature and voltage stress. Combined with part level screening and change of suppliers the customer return rate was reduced to 1%. Further improvements for part level screening were developed using Iddq as a parametric screen. The board-level screening program required a capital investment of only $50,000. Part screening increased the price of the parts by an additional 10%.