A comparison of different mechanical testing protocols on the reliability of a lead-free solder system.

摘要

With the recent demand brought about by overseas legislative efforts to eliminate and/or minimize lead (Pb) and other hazardous substances used in electronics products, there has a been a flurry of activity with regards to trying to understand the reliability of the Pb-free solder replacements. Taken individually, most of the various experiments performed to try to assess Pb-free reliability are well conducted and the results add to the much-needed body of knowledge for Pb-free reliability. However, as the extant research is conducted by different researchers and from different organizations - both university-based and industry-based - it is difficult, if not impossible, to make comparisons among all the different results. The main reasons why the comparisons are difficult are because different researchers use different Pb-free alloys, different test vehicles, and different mechanical testing techniques. The different testing techniques include shear tests (solder sphere and package), drop tests, solder sphere pull tests, and cyclical bending tests.;The purpose of this research is to perform a comprehensive study of the typically utilized mechanical testing techniques and to do so by using the same test vehicle. The test vehicle is designed based upon guidelines provided by industry standards. Even though there are industry standards, there is still room for experimental designers to create unique test vehicles; hence, the different test vehicles used by different researchers. This work will subject one test vehicle design to a spectrum of different testing techniques. All the test vehicles used in this study are assembled in the same laboratory/conditions, adding another degree of control to the experiments not possible when comparing other researchers' results. The objective of this work is to determine if, by subjecting one test vehicle design to different testing techniques, an understanding in the results of one technique can be obtained by knowing the findings of another technique. A sub-objective of this work is to determine if a complex mechanical test, namely the drop test, can be replaced by a simpler and less expensive option of testing, namely the 4 Point Cyclic Bend Test. An isothermal aging study is also done to observe the effect of aging on the reliability and the microstructure of Sn-Ag-Cu (SAC) alloy.