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Title: Solid-state growth kinetics of Ni{sub 3}Sn{sub 4} at the Sn-3.5Ag solder/Ni interface

Abstract

Systematic experimental work was carried out to understand the growth kinetics of Ni{sub 3}Sn{sub 4} at the Sn-3.5Ag solder/Ni interface. Sn-3.5%Ag solder was reflowed over Ni metallization at 240 deg. C for 0.5 min and solid-state aging was carried out at 150-200 deg. C, for different times ranging from 0 to 400 h. Cross-sectional studies of interfaces have been conducted by scanning electron microscopy and energy dispersive x ray. The growth exponent n for Ni{sub 3}Sn{sub 4} was found to be about 0.5, which indicates that it grows by a diffusion-controlled process even at a very high temperature near to the melting point of the SnAg solder. The activation energy for the growth of Ni{sub 3}Sn{sub 4} was determined to be 16 kJ/mol.

Authors:
;  [1]
  1. Department of Electronic Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China)
Publication Date:
OSTI Identifier:
20787727
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 98; Journal Issue: 12; Other Information: DOI: 10.1063/1.2149487; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ACTIVATION ENERGY; AGING; CHEMICAL ANALYSIS; CRYSTAL GROWTH; INTERFACES; MELTING POINTS; NICKEL; NICKEL ALLOYS; SCANNING ELECTRON MICROSCOPY; SILVER ALLOYS; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0400-1000 K; TIN ALLOYS

Citation Formats

Alam, M.O., and Chan, Y.C.. Solid-state growth kinetics of Ni{sub 3}Sn{sub 4} at the Sn-3.5Ag solder/Ni interface. United States: N. p., 2005. Web. doi:10.1063/1.2149487.
Alam, M.O., & Chan, Y.C.. Solid-state growth kinetics of Ni{sub 3}Sn{sub 4} at the Sn-3.5Ag solder/Ni interface. United States. doi:10.1063/1.2149487.
Alam, M.O., and Chan, Y.C.. Thu . "Solid-state growth kinetics of Ni{sub 3}Sn{sub 4} at the Sn-3.5Ag solder/Ni interface". United States. doi:10.1063/1.2149487.
@article{osti_20787727,
title = {Solid-state growth kinetics of Ni{sub 3}Sn{sub 4} at the Sn-3.5Ag solder/Ni interface},
author = {Alam, M.O. and Chan, Y.C.},
abstractNote = {Systematic experimental work was carried out to understand the growth kinetics of Ni{sub 3}Sn{sub 4} at the Sn-3.5Ag solder/Ni interface. Sn-3.5%Ag solder was reflowed over Ni metallization at 240 deg. C for 0.5 min and solid-state aging was carried out at 150-200 deg. C, for different times ranging from 0 to 400 h. Cross-sectional studies of interfaces have been conducted by scanning electron microscopy and energy dispersive x ray. The growth exponent n for Ni{sub 3}Sn{sub 4} was found to be about 0.5, which indicates that it grows by a diffusion-controlled process even at a very high temperature near to the melting point of the SnAg solder. The activation energy for the growth of Ni{sub 3}Sn{sub 4} was determined to be 16 kJ/mol.},
doi = {10.1063/1.2149487},
journal = {Journal of Applied Physics},
number = 12,
volume = 98,
place = {United States},
year = {Thu Dec 15 00:00:00 EST 2005},
month = {Thu Dec 15 00:00:00 EST 2005}
}
  • No abstract prepared.
  • Effects of electric current flow on the Kirkendall void formation at solder joints were investigated using Sn-3.5Ag/Cu joints specially designed to have localized nucleation of Kirkendall voids at the Cu{sub 3}Sn/Cu interface. Under the current density of 1 × 10{sup 4} A/cm{sup 2}, kinetics of Kirkendall void growth and intermetallic compound thickening were affected by the electromigration (EM), and both showed the polarity effect. Cu{sub 6}Sn{sub 5} showed a strong susceptibility to the polarity effect, while Cu{sub 3}Sn did not. The electromigration force induced additional tensile (or compressive) stress at the cathode (or anode), which accelerated (or decelerated) the void growth. From themore » measurements of the fraction of void at the Cu{sub 3}Sn/Cu interface on SEM micrographs and analysis of the kinetics of void growth, the magnitude of the local stress induced by EM was estimated to be 9 MPa at the anode and −7 MPa at the cathode.« less
  • The crystal structures of two new compounds were determined from single-crystal X-ray diffraction measurements: Ni{sub 3+x}Sn{sub 4}Zn, (x~1.35, a=7.110(2) Å, b=4.123(1) Å, c=10.346(3) Å, β=90.23(2)°, space group I2/m, Z=2. R1=0.025, wR2=0.059 for 748 unique reflections, 35 variable parameters) and Ni{sub 6+x}Sn{sub 8}Zn, x~1.35 (a=12.379(3) Å, b=4.095(1) Å, c=12.155(3) Å, β=116.25(3)°, space group C2/m, Z=2. R1=0.026, wR2=0.052 for 1346 unique reflections, 60 variable parameters). In addition, a structural refinement was performed for Ni{sub 3+x}Sn{sub 4}, x~0.13 (a=12.264(3) Å, b=4.066(1) Å, c=5.223(2) Å, β=104.85(3)°, space group C2/m, Z=2. R1=0.019, wR2=0.046 for 617 unique reflections, 29 variable parameters). The three compounds show pronouncedmore » similarities among each other as well as to the crystal structures of surrounding binary Ni–Sn and ternary Ni–Sn–Zn compounds. In particular, the two new compounds form a homologous series with Ni{sub 3+x}Sn{sub 4}, x~0.13. They contain “Ni{sub 4}Sn{sub 4}” and “Ni{sub 2}Sn{sub 4}” building blocks which by different interconnection build up the distinct structures. Topological relations with NiSn and Ni{sub 5−δ}Sn{sub 4}Zn, δ~0.25 are evident. - Graphical abstract: Projection of the structure of Ni{sub 6+x}ZnSn{sub 8}, x~1.35 and constituent building blocks. Display Omitted - Highlights: • The crystal structures of Ni{sub 6+x}Sn{sub 8}Zn and Ni{sub 3+x}Sn{sub 4}Zn were determined using single crystal XRD. • Topological relations to Ni–Sn and Ni–Sn–Zn compounds were established and discussed. • Common structural units were identified and their interconnection patterns described.« less
  • The binary eutectic Sn-3.5wt.%Ag alloy was soldered on the Ni/Cu plate at 250 C, the thickness of the Ni layer changing from 0 through 2 and 4 {micro}m to infinity, and soldering time changing from 30 to 120 s at intervals of 30 s. The infinite thickness was equivalent to the bare Ni plate. The morphology, composition and phase identification of the intermetallic compound (IMC, hereafter) formed at the interface were examined. Depending on the initial Ni thickness, different IMC phases were observed at 30 s: Cu{sub 6}Sn{sub 5} on bare Cu, detestable NiSn{sub 3} + Ni{sub 3}Sn{sub 4} onmore » Ni(2 {micro}m)/Cu, Ni{sub 3}Sn{sub 4} on Ni(4 {micro}m)/Cu, and Ni{sub 3}Sn + Ni{sub 3}Sn{sub 4} on bare Ni. With increased soldering time, a Cu-Sn-based {eta}-(Cu{sub 6}Sn{sub 5}){sub 1{minus}x}Ni{sub x} phase formed under the pre-formed Ni-Sn IMC layer both at 60s in the Ni(2 {micro}m)/Cu plate and at 90s in the Ni(4 {micro}m)/Cu plate. The two-layer IMC pattern remained thereafter. The wetting behavior of each joint was different and it may have resulted from the type of IMC formed on each plate. The thickness of the protective Ni layer over the Cu plate was found to be an important factor in determining the interfacial reaction and the wetting behavior.« less
  • Ni/Au metallization layers are used with increasing frequency to protect Cu substrates in ball grid array microelectronic packaging. The external Au layer provides oxidation and corrosion resistance during storage prior to assembly, while the intermediate Ni layer acts as a diffusion barrier that inhibits the formation of a thick Cu-Sn intermetallic layer during aging. During soldering with eutectic Pb-Sn, the Au dissolves into the molten solder and forms fine, needle-shaped AuSn{sub 4} intermetallic precipitates that are retained in a dense distribution in the bulk of the solder joint after it has solidified. However, recent research by Mei et al. hasmore » revealed a new and potentially problematic phenomenon that seems to be peculiar to the Ni/au metallization. They found that after extensive aging (150 C for 2 weeks in their case), the Au-Sn intermetallic redeposited onto the solder-substrate interface. The reconstituted interface was significantly weakened and failed by brittle fracture along the surface between the redeposited Au-Sn and the Ni{sub 3}Sn{sub 4} layer that formed during reflow. While the interfacial redeposition of Au-Sn intermetallics has been observed previously, the mechanism remains unknown. The present work was undertaken to identify the mechanism of this phenomenon and explore methods for controlling it.« less