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Title: Role of Cu-Sn intermetallics in wettability degradation

Abstract

Wettability of pretinned Cu decreases after long aging times. This work provides insight into the role Cu-Sn intermetallics play in wettability degradation. This study investigates the effects of aging in air and argon at 170{degree}C on Cu coupons which were pretinned with 75Sn-25Pb solder. Coating was applied using an electroplating technique. The coating thickness was controlled between 3 to 30 {mu}m and the specimens were aged for 0, 2, 24 h, and two weeks. Wetting balance tests were used to evaluate the wettability of the test specimens. Microstructural development was evaluated using x-ray diffraction, energy dispersive x-ray, and Auger spectroscopy, as well as optical and scanning electron microscopy. Results indicate that Cu-Sn intermetallics protected from oxidation do not contribute to a decrease in wettability. Oxidized intermetallics, however, significantly decrease the wettability of aged pretinned samples. The extent of degradation is determined by the type of oxide formed on the surface of the intermetallic. This study shows that a predominantly Cu oxide forms on Cu{sub 3}Sn, while a Sn oxide forms on Cu{sub 6}Sn{sub 5}. No evidence of internal oxidation was found. 20 refs., 9 figs., 1 tab.

Authors:
;  [1]
  1. Lawrence Berkeley Lab., CA (United States)|[Univ. of California, Berkeley, CA (United States)
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
171470
DOE Contract Number:
AC03-76SF00098
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Electronic Materials; Journal Volume: 24; Journal Issue: 10; Other Information: PBD: Oct 1995
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 40 CHEMISTRY; INTERMETALLIC COMPOUNDS; OXIDATION; X-RAY DIFFRACTION; ELECTRON MICROSCOPY; WETTABILITY; COPPER ALLOYS; TIN ALLOYS; ELECTRON SPECTRA

Citation Formats

Reynolds, H.L., and Morris, J.W.. Role of Cu-Sn intermetallics in wettability degradation. United States: N. p., 1995. Web. doi:10.1007/BF02655460.
Reynolds, H.L., & Morris, J.W.. Role of Cu-Sn intermetallics in wettability degradation. United States. doi:10.1007/BF02655460.
Reynolds, H.L., and Morris, J.W.. Sun . "Role of Cu-Sn intermetallics in wettability degradation". United States. doi:10.1007/BF02655460.
@article{osti_171470,
title = {Role of Cu-Sn intermetallics in wettability degradation},
author = {Reynolds, H.L. and Morris, J.W.},
abstractNote = {Wettability of pretinned Cu decreases after long aging times. This work provides insight into the role Cu-Sn intermetallics play in wettability degradation. This study investigates the effects of aging in air and argon at 170{degree}C on Cu coupons which were pretinned with 75Sn-25Pb solder. Coating was applied using an electroplating technique. The coating thickness was controlled between 3 to 30 {mu}m and the specimens were aged for 0, 2, 24 h, and two weeks. Wetting balance tests were used to evaluate the wettability of the test specimens. Microstructural development was evaluated using x-ray diffraction, energy dispersive x-ray, and Auger spectroscopy, as well as optical and scanning electron microscopy. Results indicate that Cu-Sn intermetallics protected from oxidation do not contribute to a decrease in wettability. Oxidized intermetallics, however, significantly decrease the wettability of aged pretinned samples. The extent of degradation is determined by the type of oxide formed on the surface of the intermetallic. This study shows that a predominantly Cu oxide forms on Cu{sub 3}Sn, while a Sn oxide forms on Cu{sub 6}Sn{sub 5}. No evidence of internal oxidation was found. 20 refs., 9 figs., 1 tab.},
doi = {10.1007/BF02655460},
journal = {Journal of Electronic Materials},
number = 10,
volume = 24,
place = {United States},
year = {Sun Oct 01 00:00:00 EDT 1995},
month = {Sun Oct 01 00:00:00 EDT 1995}
}
  • This work reports a theoretical study of the x-ray absorption near-edge structure spectra at both the Cu and the Mn K-edge in several Cu{sub 2}MnM (M=Al, Sn, and In) Heusler alloys. Our results show that ab initio single-channel multiple-scattering calculations are able to reproduce the experimental spectra. Moreover, an extensive discussion is presented concerning the role of the final state potential needed to reproduce the experimental data of these half-metallic alloys. In particular, the effects of the cluster size and of the exchange and correlation potential needed in reproducing all the experimental x-ray absorption near edge structure features are discussed.
  • This article reports two new Hf-rich intermetallics synthesized using Sn flux: Hf 3Fe 4Sn 4 and Hf 9Fe 4-xSn 10+x. Hf 3Fe 4Sn 4 adopts an ordered variant the Hf 3Cu 8 structure type in orthorhombic space group Pnma with unit cell edges of a=8.1143(5) Å, b=8.8466(5) Å, and c=10.6069(6) Å. Hf 9Fe 4-xSn 10+x, on the other hand, adopts a new structure type in Cmc21 with unit cell edges of a=5.6458(3) Å, b=35.796(2) Å, and c=8.88725(9) Å for x=0. It exhibits a small amount of phase width in which Sn substitutes on one of the Fe sites. Both structuresmore » are fully three-dimensional and are characterized by pseudo one- and two-dimensional networks of Fe–Fe homoatomic bonding. Hf 9Fe 4-xSn 10+x exhibits antiferromagnetic order at TN=46(2) K and its electrical transport behavior indicates that it is a normal metal with phonon-dictated resistivity. Hf 3Fe 4Sn 4 is also an antiferromagnet with a rather high ordering temperature of TN=373(5) K. Single crystal resistivity measurements indicate that Hf 3Fe 4Sn 4 behaves as a Fermi liquid at low temperatures, indicating strong electron correlation.« less
  • Thermal, microstructural and x-ray analyses, and also measurements of the electrical resistance and hardness were run on Ti-Al-Sn alloys prepared by fusion in an arc furnace having a non-consumable tungsten electrode in an argon atmosphere. Thermal analysis showed that at 1590 to l615 deg C an alloy containing 40to 80% Ti/sub 3/Sn (16 to 36% Sn) crystallizes as an eutectic mixture consisting of two phases: a beta -solid solution in a Ti-Al system and a ternary delta -solid solution on a Ti/sub 3/Sn base. The eutectic pomt corresponds to 45% Ti/sub 3/Sn (~20 wt% Sn). The addition of Ti/sub 2/Snmore » to Ti3Al decreases the alpha in equilibrium beta transition temperature from l120 deg C for Ti/sub 3/Al to a minimum of 990 deg at 60% Ti/sub 3/Sn. A microstructural analysis showed that the cast ingot consisted of a delta phase and a beta + delta ( alpha ) eutectic. An alloy of the same composition (50% Ti/sub 3/Sn, 50% Ti/sub 3/Al) consisted of a single-phase, alpha ( delta )- solid solution after annealing. An x-ray analyses of well-annealed alloys showed only a single set of lines corresponding either to alpha -titanium or to Ti3Sn. The hardness and electricaI resistance show maxima at 50 wt% Ti/sub 3/Sn in Ti/ sub 3/Al-Ti/sub 3/Sn mixtures. (TTT)« less
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