Thermal and Mechanical Reliability Tests of Lead - free soldered SMT Joints

One of the main goals in development of electronics manufacturing technology, after implementation of EU Directive RoHS, is the reliability improvement of electronic interconnection systems. Investigations of lead-free technology for small producers of electronic equipment (SME´s) were made in Warsaw University of Technology (WUT) in frame of GreenRoSE Project financed by EC. Achieved results of accelerated thermal and mechanical cycling fatigue tests of SnPb37 and lead-free SMT solder joints are presented. Two PC test boards finishes: immersion tin and leadfree HASL were applied. The samples were assembled and soldered on GreenRoSE pilot line. Thermal cycling (air to air) tests were performed in two zone thermal shock chamber. For mechanical tests was used new laboratory stand designed by WUT (Szwech and Wrona, 2006). The failures occurred during the tests were detected by four point resistance measurements and visual inspection. The results showed that achieved reliability data of lead -free soldered joints are satisfactory, however, for high reliability applications, further investigations are necessary.