Determination of the life-time of solder joints under temperature and vibration loadings

Electronic devices for automotive applications represent a big market today. The number of these devices per car significantly increased within the last years. At the same time the mounting positions of the devices are close to engine, gear or suspension structures and therefore face harsh use conditions. Nevertheless the expected lifetime of these devices is 25 years or even more. Careful and comprehensive engineering is needed to fulfil the named requirements. To access the reliability of solder joints facing the described conditions an understanding of the damage mechanism driven by vibration and thermal loads need to be gained. To address this situation vibration experiments on as reflowed as well as on isothermally pre-aged (high temperature storage, HTS) ceramic chip capacitors were accomplished at room temperature. In a further set as reflowed specimen were exposed to vibration at 125°C. A strap like PCB was used enabling a defined load introduction. A next generation of these test vehicles including local heater functionality was used to accomplish the vibration at high temperature. Crack growth and failure cycles were investigated. Life time models for the different loading conditions were determined using experimental and simulation results.