Growth Behavior of IMCs on <001>-oriented and Large-grain electroplated Cu substrate

In recent years, electronic components have become more and more miniaturized, intelligent and multifunctional. This has been followed by a more complex problem that the working environments of electronic components are getting harsher and worse. It is well known that the aggressive growth of intermetallic compounds (IMCs) formed at the interface of solder/substrate during soldering can extremely degrade the mechanical properties and reliability of the resultant solder joints in electronic packaging. In this study, we prepared a <001>-oriented and large-grain electroplated Cu as substrate. Then the growth behavior of the IMCs at Sn/electroplated Cu as well as Sn/rolling-annealed Cu interfaces was investigated. By observing the IMC morphology, it was found that the Cu6Sn5 thickness on the electroplated Cu was smaller than that on the rolling-annealed Cu, while the Cu3Sn thickness was not significantly different for both Cu substrates. Also, no Kirkendall voids were formed at the Sn/electroplated Cu interface after reflow, implying good reliability for the solder joints based on the electroplated Cu substrate. Growth kinetics analysis reviewed that the Cu6Sn5 growth on the electroplated Cu substrate was mainly controlled by grain boundary diffusion.