Automatic Pattern Generation for Diagnosis of Wiring Interconnect Faults

Abstract

This paper introduces a unified approach to automatic pattern generation for diagnosis of board-level wiring defects between modules both with and without boundary scan. The fault model for wiring defects includes bridging faults, stuck-at faults and open faults. We show that complete diagnosis of I/O faults can be achieved by considering single faults only rather than fault pairs and we have modified a traditional sptem that supports single stuck fault test generation to also perform pattern generation for complete diagnosis. Rather than building a fault dictionary from detection patterns, we introduce distinguishing functions, a fault diagnosis tree and heuristics to resolve signatures of faults so that they become unique or are proven equivalent. Experimental results with large benchmark circuits show that complete diagnosis for stuck-at as well as bridging I/O faults is possible. The number of patterns for complete diagnosis compares favorably with patterns required for first detection of single stuck-at faults only.