Techniques to Solve TPS Performance Weaknesses

Critical weaknesses in Test Program Set (TPS) designs can be deceiving and remain unknown causing diagnostic and performance problems. These can include weak mainline test flow with intermittent pass/fails, poor diagnostics with unacceptable fault detection algorithms, and/or ReTest Okay (RTOK) and Cannot Duplicate (CND) problems. Often associated with No-Fault-Found (NFF) conditions, their causes can include test limit variations, poor test program development practices, incorrect diagnostic callouts or even Automatic Test Equipment (ATE) performance issues. Also, these performance weaknesses may be attributed to Interface Test Adapter (ITA) design, test equipment selection and settings, power supply problems, wiring discrepancies, crosstalk, timing issues, speed, noise, physical connections and the test program software itself, Full understanding of TPS performance problems is often elusive as a result of symptoms that can be extremely deceiving where alternative methods for their resolution should be considered. This paper describes some of these methods and their usefulness.