Diagnosis in modem design - just the tip of the iceberg

When test is done right, that is to an acceptable quality specification (and without impeding productivity and cost), defective parts fail the screening process. Without splitting hairs on definition, diagnosis and debug digs deeper to determine why the part is unacceptable. Troubleshooting how and why a part (or system) fails is important. For example, this may be needed for yield improvement, process monitoring, debugging the design function, failure mode learning for R&D, or just getting a working first prototype. But the detective work can become tricky. One reason for this is that, while many segments of the product creation flow (e.g. the design and test development flows) have benefited from years of study and automation, diagnosis has somewhat lagged in the formalization of techniques. Also, the test floor equipment have been traditionally designed and operated for pass/fail oriented testing. Unless this situation improves, an effective diagnosis-friendly environment may be elusive when it is needed most.