Measurement method for failure prognosis in lead-free interconnections

The specification of a reliability criterion for solder joints is an important element in the qualification of an electronic product, in particular for the new lead-free alloys. A common approach to reliability evaluation for soldering is to monitor electrical resistance after, or better during, the testing. The techniques employed for DC resistance monitoring will capture information regarding transients or long-term drift. This paper reviews and assesses the DC resistance monitoring during reliability testing of lead-free solder material used for the implementation of an ultrasound transducer. An experimental study on a transducers implemented with soldering made up by In-Sn was performed to compare reliability performance with Sn-Pb soldering and measurement techniques. Moreover we would propose to use a method for failure prognosis, considering measurements with changes of frequency, in order to evaluate the possibility to identify the failure occurrence earlier than the DC resistance.