Solder Joint Reliability Predictions for Leadless Chip Resistors, Chip Capacitors, and Ferrite Chip Inductors Using the SRS Software

Abstract

The SRSTM software provided reliability predictions regarding the thermal mechanical fatigue (TMF) failure of solder joints for three sizes of chip resistor, three sizes of chip capacitor, as well as three sizes and three material compositions of ferrite chip components (inductors) assembled on a laminate printed wiring board. Four “use” conditions and one accelerated testing condition were assessed using an end-of-life failure rate criterion of 10 ppm for the service conditions and an 50% end-of-life failure rate after accelerated testing. The chip resistors and capacitors would provide reliable electrical functionality over the entire product lifetime. Significant TMF in the gap location would reduce the mechanical strength of the joints. The ferrite components would also provide reliable electrical functionality over the entire product lifetime. A lower joint strength would be expected in some of the joints due TMF in the gap location. The accelerated test conditions were predicted to cause a decrease in mechanical strength for the resistor, capacitor, and ferrite component solder joints, more so in the case of the resistors and capacitors and to a lesser degree for the ferrite devices, due to TMF in the solder joint gap locations. However, a predicted absence of TMF failure in the solder joint fillets would result in, no catastrophic loss of mechanical integrity or the loss of electrical performance to the solder interconnects of the devices.