In-situ reliability monitoring on PBGA packaging through piezoresistive stress sensor

It is well known that the CTE mismatch and the hygroscopic swelling mismatch in a plastic packaging lead reliability issues so that a suitable extraction methodology on packaging stress and failure parameters are needed. To this end, we first designed and made the piezoresistive stress sensors for packaging stress measurements and performed the sensor calibrations. Test chips were next packaged into a typical plastic packaging and the hygroscopic stress were measured. Finally, a reliability test was performed to extract the long-term effects and the reliability parameters. It is concluded from the works that the hygroscopic mismatch stress is about 50 MPa and it is significant for the packaging. It is also concluded that the Weibull reliability model is suitable for the PBGA packaging, and the Weibull parameters were successfully extracted.