ANOTHER LOOK AT LEAD-FREE SOLDER JOINT RELIABILITY UNDER RANDOM VIBRATION

摘要

In recent years a growing concern for lead-free solder has propelled industry to re-evaluate surface mount technology (SMT) production. This is based on the European Union's reduction of hazardous substances (RoHS) directive for a cleaner environment. Military and Aerospace industries, though they have been given exemption from this directive, are very dependent upon commercial industry that must be RoHS compliant. Therefore RoHS issues are important to Military and Aerospace industries. Commercial industries are not required to meet the rugged environmental standards required for military and aerospace applications. It is necessary for further research to be conducted on commercial lead-free solders (using military standards) that will be used for military applications. The varying properties of lead-free solders as compared to the Tin Lead (SnPb) model have made it so that traditional methods of processing can no longer be utilized, thus raising Diminishing Manufacturing Sources and Material Shortages (DMSMS) concerns within the military and aerospace communities. Lead-free solder properties vary with the percentage of alloy composition, heat treatments and crystallography. Further research is needed in characterizing and creating valid models for lead-free solder joint reliability. The Microelectronics Testing and Technology Obsolescence Program (METTOP) is a small microelectronics testing and research facility located at New Mexico Tech, in Socorro, NM. Our facility has recently started a lead-free solder research program, to assist in mitigating DMSMS issues and concerns regarding reliability-information, or the lack there of, on lead-free solders for use in Military and Aerospace applications. Our initiative is to conduct smaller research projects making contributions to the greater body of knowledge by filling in gaps of current research. Our initial efforts are focused on performing vibration reliability testing of lead-free alloys. This paper documents the most recent results of the research done at New Mexico Tech.