Relationship Between the Intermetallic Compounds Growth and the Microcracking Behavior of Lead-Free Solder Joints

Abstract

This paper investigates the formation and the growth of the intermetallic compound (IMC) layer at the interface between the Sn3.0Ag0.5Cu Pb-free solder and the Cu substrate during isothermal aging at 150 °C. We measure the thickness of the IMC layer and the roughness of the solder/IMC interface, and these two factors are assumed to control the tensile behavior of the solder joints. First, it utilizes the tensile tests of the aged solder joints for analyzing the effect of the IMC growth on the tensile behavior of the solder joints. Then, the microcracking behavior of the IMC layer is investigated by finite element method (FEM). In addition, qualitative numerical simulations are applied to study the effect of the IMC layer thickness and the solder/IMC interfacial roughness on the overall response and the failure mode of solder joints. The experimental results indicate that when the aging time increases, both the thickness and the roughness of the IMC layer have a strong influence on the strength and the failure mode of solder joints. The numerical simulation results suggest that the overall strength of solder joints is reduced when the IMC layer is thick and the solder/IMC interface is rough, and the dominant failure mode migrates to the microcracks within the IMC layer when the IMC layer is thick and the solder/IMC interface is flat.

Physical properties of niobium-based intermetallics (Nb3B; B = Os, Pt, Au): a DFT-based ab-initio study

“…The blue color shows the high charge (electron) density and red color shows low charge (electron) density. So, Os atoms have high electron density compared to Nb atoms for Nb 3 Os, this also agrees with the Mulliken charge analysis. On the other hand, Nb atoms have greater charge density than Pt atoms for Nb 3 Pt.…”

“…First principles calculations based on the DFT have been used to investigate a number of physical properties of niobium based intermetallic Nb 3 and Nb 3 Pt. The Debye temperatures of the intermetallics are low.…”

“…The calculated Debye temperature Θ D of the intermetallics along with the sound velocities v l , v t , and v a are presented in Table 4. Table 4 Density ρ (in g/cm 3 [72], were obtained from the analysis of the specific heat data. Two methods yield somewhat different values of but the trend remains the same.…”

“…TDOSs around the Fermi level of Nb 3 Os have a number of peaks, which suggest that a dramatic change in physical properties may occur if the Fermi level is shifted by doping, applied stress, etc. It can be seen from TDOSs curves that there are 2 and 4 bonding peaks below the Fermi level for Nb 3 Pt and Nb 3 Os, respectively.…”

“…In the progress of many technologically important science and engineering sectors, intermetallic compounds have played a notable role. Intermetallic compounds are one of the oldest and most important condensed phases, being a subject of constant interest of physicists, chemists and materials scientists [1][2][3][4][5][6][7][8]. Large number of intermetallic compounds exhibit attractive combination of physical and mechanical properties, including high melting point, low density and good oxidation or corrosion resistance.…”