Electromigration and 4D microtomography in Sn-Bi-In thermal joints

Abstract

This proposal aims to deepen the understanding of the microstructures formed in the as-soldered Sn-Bi-In/Copper joints. Sn-Bi-In alloys are becoming alternative applications for thermal joints, also known as Thermal Interface Materials (TIM) in microelectronic circuitry. This is because with the routine increase in the power density of microelectronic components and consequent heat generation, there is a need for advances towards miniaturization, performance improvements and greater reliability of the microelectronic systems. Hence, any TIM alloy must be characterized by high thermal conductivity and excellent wettability. The development of new TIM Sn-Bi, Sn-Sb, Sn-Bi-In and Sn-Bi-Ga alloys has been carried out in the M2PS (Microstructure and Properties in Solidification Processes) group at DEMa-UFSCar for at least 10 years (FAPESP Research Grant #2019/23673-7). In this proposal, it is aimed the use of advanced characterization techniques in the performance evaluation of Sn-Bi-In alloys under service conditions. This comprises electromigration and 4D microtomography tests with application of thermal cycling in order to evaluate the generation of defects and growth of the interfacial reaction layer simulating real applications. X-ray microtomography may be used on order to generate 3D reconstructions of both surface and internal features such as interfaces. This research also aims to provide the researcher and his team of students at DEMa-UFSCar with new skills in the evaluation of microelectronic interconnections. The choice of the Center for 4D Materials Science located at Purdue University is based on: i. Excellence in electronic materials research; ii. Experience of renowned researchers, such as Prof. Nikhilesh Chawla; and iii. High-level infrastructure to implement this proposal. The aim is to produce Sn-Bi-In/copper welded joints, manufacture the samples on a submillimeter geometry for evaluation of both electromigration and temperature variation in the formation of the interfacial layer and void generation. For interfaces in thermal joints, aspects such as wettability, thickness and nature of the IMC reaction layer (or possible layer-suppression), in addition to the dissolution of the substrate forming element and generated microstructure are of fundamental importance, which control not only thermal conductivity but also strength and corrosion. (AU)