Diagnosing and fixing on-chip ESD product qualification failures can often be one of the more challenging aspects of work in ESD. The pressure to quickly find and correct an HBM/MM/ CDM failure to qualify a product often compounds the inherent difficulty of troubleshooting. Experience diagnosing failures, though not desirable from a product qualification standpoint, can greatly improve troubleshooting skills. This tutorial will build troubleshooting experience and skills by presenting case studies of actual on-chip HBM failures in a workshop format. The evidence for each case will be revealed and the failure analyzed in the same manner as an actual failure. Participants will be led through and allowed to analyze each failure case, interacting with the instructor to determine its root cause and a solution. The tutorial will identify common concepts, methods, and tools useful in failure diagnosis. Participants should be familiar with CMOS technology, on-chip ESD breakdown phenomena, standard ESD protection circuits, and the HBM test procedure.