Life-time Tests of Lead-free Solder Joints on Flexible Printed Circuits

The electronics industry is in the transition to lead-free technology, and it is very important for all industrial performers, including small and medium size enterprises (SMEs), to keep pace with this process. FlexNoLead (Flexible Circuits Processing, Performance and Reliability using Lead-Free Soldering Process, EC Contract: COOP-CT-2004-513163), a European Commission sponsored cooperative research project is aimed at assisting SMEs in the electronics production field by establishing solutions to the assembly of flexible circuits using new environmental friendly, lead-free technologies. The project lays special attention on new materials combinations of the flexible substrates in conjunction with life-time assessment and reliability prediction techniques, for the requirements of lead-free assembling. In the paper, the general requirements of flexible substrate materials, as well as, soldered and alternative joints, the theoretical considerations of the applicability of combined accelerated life-time test methods and the results of some experimental works are discussed.