Reliability Parametric Z-score Monitoring
HanCheng Ong, Seagate Technology International
Reliability engineering has very much been centered on looking at the percentage of units that survives at some specified time. In fact, monitoring the parametric performance of the product is also of great importance in areas where failure rate is low or testing is expensive. By tracking the Reliability parametric, we can provide feedback to the team on the areas of weaknesses so that product improvements can be make at early design stage. A system has been build to enable Reliability parametric data to be extracted and stored in Oracle database. For each of the parameters that are being monitored, its descriptive statistics can be tabulated and charted by various product configurations. JMP scripting is used as the platform to accomplish this. The parameters can be compared by lot configurations or performance with time. In addition to the usual descriptive statistics such as mean and standard deviation, Design for Six Sigma (DFSS) measure is employed. The data set for each test configurations are distribution fitted using all available parametric models in JMP. The best-fitted distribution is used to obtain the PPM with the specification limits for computing the Z-score (DFSS measure of quality) for the parameter. The Z-scores are tabulated and charted for monitoring as indicators of quality