Thermal fatigue damages in SMC solder joints: SEM/EDS fractography observations

摘要

A raised concern in the electronic packaging industry is the thermal fatigue (TF) that occurs when materials connected by solder-joints (SJ) and having different thermal expansion coefficients undergo power on-off cycling or environmental temperature cycling. Since there is not a universal agreement on SJ fatigue reliability standards, and existing ones may not address all the issues encountered when soldering electronic components, the role of direct microscopical observations of TF damages can not be overestimated. It holds true in particular when going to new surface mount components (SMC's), PCB's or soldering technology and facing with any discord and uncertainty in the assessment of TF reliability. SEM/EDS Fractography represents the most suitable technique to attain these ends; the questions which should be answered here are how to expose TF damages and how to differentiate them from other defects.