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

Volume

23

Issue

2

fYear

2000

fDate

6/1/2000 12:00:00 AM

Firstpage

383

Lastpage

387

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 Au_0.5Ni _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 Au_0.5Ni_0.5Sn₄ 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; Au_0.5Ni_0.5Sn₄; 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;

fLanguage

English

Journal_Title

Components and Packaging Technologies, IEEE Transactions on

Publisher

ieee

ISSN

1521-3331

Type

jour

DOI

10.1109/6144.846778

Filename

846778