Specifically, in the Phase 8 reliability report, the stress tests performed include field reliability experience, early life failure and wear-out capability and board level reliability and thermo-mechanical capability. Under field reliability, it examines field, assembly and applications failures, and intrinsic die qualification. Likewise, under early life failure and wear-out capability, it investigates early life-failure rate and electromigration. While under board level reliability and thermo-mechanical capability, it checks intermittent operating life, temperature cycling and board-level reliability.
EPC’s root cause analysis breaks down all field failures into root cause categories. (Image Credit: Efficient Power Conversion).
The report indicates that a total of 127 field failures have been investigated so far. Of the 127
returned units, 37 devices passed electrical testing with no anomalies detected, and were therefore classified as good units. Of the remaining 90 field failures, 75 units were analyzed as failures due to assembly problems (the highest number of field returns) and 12 were categorized under applications or circuit design. Similarly, 3 units were labeled as device degradation.
In March, the company released the Phase 7 reliability report, showing the distribution of over 17 billion accumulated field-device hours and detailing test data from more than 7 million equivalent device-hours under stress. The stress tests included intermittent operating life (IOL), early life failure rate (ELFR), humidity with bias, temperature cycling and electrostatic discharge. The study reported a composite 0.24 failures in time (FIT) rate for products in the field for nearly six years.
