Title :
Solder metallization interdiffusion in microelectronic interconnects
Author :
Zribi, A. ; Chromik, R.R. ; Presthus, R. ; Teed, K. ; Zavalij, L. ; DeVita, J. ; Tova, J. ; Cotts, Eric J. ; Clum, James A. ; Erich, Robert ; Primavera, A. ; Westby, G. ; Coyle, R.J. ; Wenger, G.M.
Author_Institution :
Dept. of Phys., State Univ. of New York, Binghamton, NY, USA
fDate :
6/1/2000 12:00:00 AM
Abstract :
We investigated the growth of intermetallic compounds in Cu/Ni/Au/PbSn solder joints. The substrates that we investigated had been Au plated by one of two different techniques. The Au finish thicknesses ranged from 0.25 to 2.6 μm. After solder renew, structural examinations using optical and electron microscopy of cross-sectioned solder joints revealed the growth of Ni3Sn 4 at the solder/Ni interface after reflow. Solder joints with thicker layers of Au annealed in Ar gas at a temperature of 150°C for up to 450 h, displayed an appreciable growth of Au0.5Ni 0.5Sn4 at the Ni3Sn4/solder interface. Previous investigators correlated growth of a Au-Sn alloy with the degradation of the mechanical properties of the solder joint. The determination of the stoichiometry of the Au0.5Ni0.5 Sn4 phase provides some understanding of why this phase grew at the Ni3Sn4/solder interface, as Sn, Au and Ni are all readily available at this interface. The growth of this ternary alloy is also consistent with trends observed in the kinetics of formation of solder alloys
Keywords :
ageing; chemical interdiffusion; copper; gold; gold alloys; integrated circuit interconnections; integrated circuit packaging; metallisation; microassembling; nickel; nickel alloys; printed circuit manufacture; reflow soldering; stoichiometry; tin alloys; Au finish thicknesses; Au0.5Ni0.5Sn4; Cu-Ni-Au-PbSn; Cu/Ni/Au/PbSn solder joints; Ni3Sn4; Ni3Sn4/solder interface; intermetallic compound growth; microelectronic interconnects; solder metallization interdiffusion; solder reflow; solder/Ni interface; structural examinations; ternary alloy; Annealing; Electron microscopy; Electron optics; Gold; Intermetallic; Metallization; Microelectronics; Optical microscopy; Soldering; Tin;
Journal_Title :
Components and Packaging Technologies, IEEE Transactions on
DOI :
10.1109/6144.846778
