Macroscopic Manifestations of Intermetallic Compound Transformations during Thermal Treatment and Reflow

Intermetallic compounds (IMC) formation and growth are critical factors in evaluating the integrity of the base metal-solder interface, which are strongly affected by thermal treatment such as aging and reflow condition. These thermal treatments are essential in the assembly manufacturing of semiconductor and electronic devices. Herein, we demonstrate the effect of thermal treatment and reflow on the formation and integrity of IMCs in NiAu/Sn-3.0Ag-0.5Cu/NiAu sandwich systems. The deterioration and partial recovery in the macroscopic behavior manifested as shear strength as a function of thermal treatment and reflow are explained by the transformations in the IMCs: grain growth, grain boundary reduction, embrittlement, and IMC dispersion