Power supply ESS: A case study evaluating IPC 9592A recommendations

In 2010, IPC released 9592A, “Performance Parameters for Power Conversion Devices”. The standard includes descriptions of Highly Accelerated Stress Screening (HASS) and Highly Accelerated Stress Audits (HASA) for PCD (Power Conversion Device) ESS, and describes them as more effective than Burn-In. A case study comparing the effectiveness of Burn In with Highly Accelerated Stress Audits (HASA) has demonstrated the greater effectiveness of HASA. Implemented at a high volume PCD manufacturer for a one year period, the study determined that HASA, run after a tradition Burn-In process, caught failures that the Burn-In process was unable to discover. Failure rates of PCDs in Burn-In were 0.002% of the units, whereas failures in HASA were 1.25% of the units tested. Further, field warranty failures for units run through HA SA were non-existent whereas warranty failure rates of PCDs run only through Burn-In were 0.15%, a material economic difference in such high volume PCDs. The paper concludes that the IPC 9592A recommendations for using HASS and HASA in PCD manufacturing are well-founded, and that they are demonstrably superior to Burn-In for reducing field failure rates.