Study on reliability of PQFP assembly with lead free solder joints under random vibration test

• Reliability assessment method was developed for lead joint under random vibration test.
• The PCB and PQFP are 2 individual vibration systems under random vibration test.
• Solder is prone to failure than Cu lead for PQFP package under random vibration test.
• Range-pair cycle-counting method provides a conservative fatigue life prediction.
• High-speed camera was successfully used in dynamic analysis for the PCB and joint.

Harsh solder joint reliability testing is needed for high frequency vibration requirements particularly for automotive electronics. In this study, the solder joint reliability for the plastic quad flat package (PQFP) which was mounted on the printed circuit board (PCB) using 95.5Sn–3.8Ag–0.7Cu lead-free solder was investigated using the random vibration test. A high-speed camera was used to capture dynamic response of the PCB and PQFP lead during the random vibration test. The displacement measurement result was used in finite element analysis (FEA) as an input displacement loading to evaluate the stress–strain behavior of the PQFP lead and solder joint. Fatigue life prediction for the copper (Cu) lead and PQFP solder joint was carried out using three different cycle-counting methods and the Miner's law. It was shown that solder fatigue failure is more critical than Cu lead failure for the PQFP assembly under the random vibration test.