Dr. Fiqiri Hodaj, Professor, Grenoble Institute of Technology (Grenoble INP), School of Engineering in Physics, Electronics & Materials Science, SIMAP Laboratory, France

Title: Fundamental issues during soldering in microelectronics

Abstract: SIntegration technology, such as three-dimensional (3D) stacking, by reduction of interconnection length, enables a significant increase of the whole device performance. Cu and Ni are the most common conductor metals utilized in contact with Sn-based solder alloys, which are nowadays the most used lead-free solders in microelectronic industry. Fabrication of integrated circuits includes numerous reflows of solder/Cu and/or solder/Ni contacts. During a reflow, several processes occur such as melting of the solder, wetting of the substrate by the liquid solder, interfacial reaction at the solder/substrate interface and solidification of unreacted solder. Each of these processes can play a crucial role on the subsequent evolution of the joint, and their control becomes more and more complex with the continuing trend towards increasing miniaturization. In this talk, we will present results obtained from wetting experiments as well as from isothermal holding experiments, performed at different temperatures. Moreover, measurements of undercooling of solder alloys, under different geometrical configurations performed by differential scanning calorimetry, will be presented. Finally, some theoretical thermodynamic and kinetic aspects on wetting, nucleation and interfacial interactions between solder alloys and Cu and Ni substrates will be presented and discussed based on the obtained experimental results.

Keywords: electronic-packaging, thermodynamics, interfacial reaction, wetting, reactive diffusion