Transient Simulation and Experimental Study of Intermetallic Formation using Sn/Cu/Sn Preforms in Inductive Chip-Level Solid-Liquid Interdiffusion Bonding for Microelectronics Applications

Abstract This study presents a combined experimental investigation and finite element analysis (FEA) of intermetallic compound (IMC) formation during transient inductive chip-level bonding using a PFDS400 Sn/Cu/Sn multilayer preform foil (8 µm Sn/34 µm Cu/8 µm Sn, 10 × 10 mm 2 ) and a silicon chip (10 × 10 × 0.5 mm 3 ). In this paper, an improved FE simulation model incorporating transient electromagnetic (EM) induction heating and IMC evolution was developed and validated experimentally. Two case studies with 250 and 275 °C as target temperatures were investigated using an induction generator with a maximum frequency of 2 MHz. The key results demonstrate that EM inductive heating was first applied to establish the local temperature distribution, followed by diffusion simulation to predict IMC formation. The formation of the intermetallic phases Cu 6 Sn 5 and Cu 3 Sn was observed, with growth rates strongly dependent on temperature. The results indicate reasonable agreement between the simulated phase formation and the metallographic observations. The study also shows that the FE model enables reliable prediction of local heat distribution and subsequent IMC formation, thereby providing a promising and robust tool for optimizing inductive bonding processes in microelectronic packaging.