<p>A major problem faced by electronic packaging industries is the poor reliability of lead free solder joints.&nbsp; One of the most common methods utilized to tackle this problem is by doping the alloy with other elements, especially bismuth.&nbsp; Researches have shown Bismuth doped solder joints to mostly fail near the Intermetallic (IMC) layer rather than the bulk of the solder joint as commonly observed in traditional SAC305 solder joints.&nbsp; An understanding of the properties of this IMC layer would thus provide better solutions on improving the reliability of bismuth doped solder joints.&nbsp; In this study, the authors have used three different lead free SAC+BI solders doped with 1%, 2% and 3% bismuth.&nbsp; Joints of these alloys were created on copper substrates.&nbsp; The joints were then polished to clearly expose the IMC layers.&nbsp; These joints were then aged at 125 °C for 0, 1, 2, 5 and 10 days.&nbsp; For each aging condition, the elastic modulus and the hardness of the IMC layers were evaluated using a nanoindenter.&nbsp; The IMC layer thickness and the chemical composition of the IMC layers were also determined for each alloy at every aging condition using Scanning Electron Microscopy (SEM) and EDS. &nbsp;The results from this study will give a better idea on how the percentage of bismuth content in lead free solder affects the IMC layer properties and the overall reliability of the solder joints.</p><p>&nbsp;</p>

Effects of Aging on the Properties of Intermetallic Layers in SAC+Bi Solder Joints

Paper Proceedings: https://asmedigitalcollection.asme.org/InterPACK/InterPACK2021/volume/85505

ASME 2021 International Electronic Packaging Technical Conference and Exhibition (InterPACK2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.