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1.
B. A. Cook I. E. Anderson J. L. Harringa S. K. Kang 《Journal of Electronic Materials》2003,32(12):1384-1391
Solder joints were prepared from seven eutectic and near-eutectic Sn-based compositions and characterized for electrical resistivity
after 100 h and 1,000 h of isothermal aging at 423 K. The solder joint samples were prepared by hand soldering to copper substrates,
and the post-heat treatment resistivity was measured at room temperature in a specially designed, four-point probe fixture.
Compositions tested included Sn-3.5Ag, Sn-3.7Ag-0.9Cu, Sn-3.0Ag-0.5Cu, Sn-3.6Ag-1.0Cu, and Sn-3.9Ag-0.6Cu. In addition, the
effect of a minor addition of a fourth element, designed to improve high-temperature shear strength, was also evaluated in
the compositions Sn-3.7Ag-0.6Cu-0.3Co and Sn-3.7Ag-0.7Cu-0.2Fe. The observed changes in electrical resistivity are discussed
in terms of microstructural coarsening, diffusional transport from the substrate, and nucleation of precipitate phases. 相似文献
2.
L. Snugovsky C. Cermignani D. D. Perovic J. W. Rutter 《Journal of Electronic Materials》2004,33(11):1313-1315
Early studies of Ag-Sn and Cu-Sn binary alloys showed very low values, 0.04 wt.% for Ag and 0.0063 wt.% for Cu, for the solid
solubility of these elements in Sn at the eutectic temperature. In recent work on “as-cast” Sn-Ag-Cu solder alloys, much higher
values have been reported for the Ag and Cu content of the Sn phase. In the present study, wavelength dispersive x-ray microprobe
measurements made on a near-equilibrium sample confirmed the earlier solubility values. It was concluded that higher values,
some of which are reported in the current paper, represent nonequilibrium, supersaturated solid solutions. 相似文献
3.
Alloying effects in near-eutectic Sn-Ag-Cu solder alloys for improved microstructural stability 总被引:7,自引:0,他引:7
I. E. Anderson J. C. Foley B. A. Cook J. Harringa R. L. Terpstra O. Unal 《Journal of Electronic Materials》2001,30(9):1050-1059
This study included a comparison of the baseline Sn-3.5Ag eutectic to one near-eutectic ternary alloy, Sn-3.6 Ag-1.0Cu and
two quaternary alloys, Sn-3.6Ag-1.0Cu-0.15Co and Sn-3.6Ag-1.0 Cu-0.45 Co, to increase understanding of the beneficial effects
of Co on Sn-Ag-Cu solder joints cooled at 1–3 C/sec, typical of reflow practice. The results indicated that joint microstructure
refinement is due to Co-enhanced nucleation of the Cu6Sn5 phase in the solder matrix, as suggested by Auger elemental mapping and calorimetric measurements. The Co also reduced intermetallic
interface faceting and improved the ability of the solder joint samples to maintain their shear strength after aging for 72
hr at 150 C. The baseline Sn-3.5Ag joints exhibited significantly reduced strength and coarser microstructures. 相似文献
4.
5.
The electrical resistivity of tin-lead eutectic solder was found to increase upon tension. The effect was partially reversible.
The fractional change in resistance per unit strain was 60. The irreversible part of the effect was due to plastic deformation. 相似文献
6.
A. Zribi A. Clark L. Zavalij P. Borgesen E. J. Cotts 《Journal of Electronic Materials》2001,30(9):1157-1164
The evolution of intermetallics at and near SnAgCu/Cu and SnAgCu/Ni interfaces was examined, and compared to the behavior,
near PbSn/metal and Sn/metal interfaces. Two different solder compositions were considered, Sn93.6Ag4.7Cu1.7 and Sn95.5Ag3.5Cu1.0 (Sn91.8Ag5.1 Cu3.1 and Sn94.35Ag3.8Cu1.85 in atomic percent). In both cases, phase formation and growth at interfaces with Cu were very similar to those commonly observed
for eutectic SnPb solder. However, the evolution of intermetallics at SnAgCu/Ni interfaces proved much more complex. The presence
of the Cu in the solder dramatically altered the phase selectivity at the solder/Ni interface and affected the growth kinetics
of intermetallics. As long as sufficient Cu was available, it would combine with Ni and Sn to form (Cu,Ni)6)Sn5 which grew instead of the Ni3Sn4 usually observed in PbSn/Ni and Sn/Ni diffusion couples. This growing phase would, however, eventually consume essentially
all of the available Cu in the solder. Because the mechanical properties of Sn-Ag-Cu alloys, depend upon the Cu content, this
consumption can be expected to alter the mechanical properties of these Pb-free solderjoints. After depletion of the Cu from
the solder, further annealing then gradually transformed the (Cu,Ni)6Sn5 phase into a (Ni,Cu)3Sn4 phase. 相似文献
7.
Thermal cycling from room temperature to 60°C was found to cause the contact resistivity of a silver-epoxy conductive adhesive
joint to decrease irreversibly, due to an irreversible decrease of the thickness of the joint. This effect was much smaller
for a soldered joint cycled to 40°C. An extended period of current on-off cycling caused a slight irreversible increase in
the contact resistivity of the adhesive and soldered joints, but thermal cycling using a heater did not. Within each thermal
cycle, the contact resistivity increased reversibly with increasing temperature, due to the increase in volume resistivity
of the solder or adhesive. Temperature variation caused fractional changes in contact resistivity up to 48% and 6% for adhesive
and soldered joints, respectively. 相似文献
8.
Effect of rare earth element addition on the microstructure of Sn-Ag-Cu solder joint 总被引:6,自引:0,他引:6
Bo Li Yaowu Shi Yongping Lei Fu Guo Zhidong Xia Bin Zong 《Journal of Electronic Materials》2005,34(3):217-224
The effects of minimal rare earth (RE) element additions on the microstructure of Sn-Ag-Cu solder joint, especially the intermetallic
compounds (IMCs), were investigated. The range of RE content in Sn-Ag-Cu alloys varied from 0 wt.% to 0.25 wt.%. Experimental
results showed that IMCs could be dramatically repressed with the appropriate addition of RE, resulting in a fine microstructure.
However, there existed an effective range for the RE addition. The best RE content was found to be 0.1 wt.% in the current
study. In addition to the typical morphology of Ag3Sn and Cu6Sn5 IMCs, other types of IMCs that have irregular morphology and uncertain constituents were also observed. The IMCs with large
plate shape mainly contained Ag and Sn, but the content of Ag was much lower than that of Ag3Sn. The cross sections of Cu6Sn5 IMCs whiskers showed various morphologies. Furthermore, some eutectic-like structures, including lamellar-, rod-, and needle-like
phases, were observed. The morphology of eutectic-like structure was related to the RE content in solder alloys. When the
content of RE is 0.1 wt.%, the needle-like phase was dominant, while the lamellar structure prevailed when the RE content
was 0.05 wt.% or 0.25 wt.%. It is suggested that the morphology change of the eutectic-like structure directly affects the
creep properties of the solder joint. 相似文献
9.
10.
Jae-Yong Park Rajendra Kabade Choong-Un Kim Ted Carper Steven Dunford Viswanadham Puligandla 《Journal of Electronic Materials》2003,32(12):1474-1482
This paper illustrates the influence of Au addition on the phase equilibria of Sn-Ag-Cu (SAC) near-eutectic alloys and on
the interface reaction with the Cu substrate. From the thermal and microstructural characterization of Sn-3.8Ag-0.7Cu alloys
containing various amounts of Au, it is found that the Au promotes the formation of a quaternary-eutectic reaction at 204.5°C
± 0.3°C. The equilibrium phases in the quaternary-eutectic microstructure are found to be AuSn4, Ag3Sn, βSn, and Cu6Sn5. While the addition of Au to Sn-3.8Ag-0.7Cu alloys is also found to increase liquidus temperature and the temperature ranges
of the phase equilibria field for primary phases, such influences from Au are found to be less pronounced when the alloys
were reacted with the Cu substrate. Because of the formation of the Au-Cu-Sn-ternary interface intermetallic, it is found
that a majority of Au added to the solder is drained from the melt. The drainage of Au reduces the impact of Au on the phase
equilibria of the solder alloys in the joint. It is further found that the involvement of Au in the interface reaction results
in a change of the interface phase morphology from the conventional scallop structure to a compositelike structure consisting
of (AuCu)6Sn5 grains and finely dispersed, βSn islands. 相似文献
11.
I. Ohnuma M. Miyashita K. Anzai X. J. Liu H. Ohtani R. Kainuma K. Ishida 《Journal of Electronic Materials》2000,29(10):1137-1144
We have recently developed a thermodynamic database for micro-soldering alloys which consists of the elements Pb, Bi, Sn,
Sb, Cu, Ag, Zn, and In. In this paper, the phase equilibria and the related thermodynamic properties of the Sn-Ag-Cu base
alloys are presented using this database, alloy systems being one of the promising candidates for Pb-free solders. The isothermal
section diagrams of the Sn-Ag-Cu ternary system were experimentally determined by SEM-EDS, x-ray diffraction and metallographic
techniques. Based on the present results as well as the previous data on phase boundaries and thermochemical properties, thermodynamic
assessment of this system was carried out. The isothermal and vertical section diagrams, liquidus surface, mass fractions
of the phase constitution, etc., were calculated. The predictions of surface energy and viscosity were also investigated.
Moreover, a non-equilibrium solidification process using the Scheil model was simulated and compared with the equilibrium
solidification behavior in some Sn-Ag-Cu base alloys. Calculated results based on the Scheil model were incorporated into
a three-dimensional solidification simulation and the prediction of practical solidification procedures was performed. 相似文献
12.
The mechanical and electrical properties of several Pb-free solder joints have been investigated including the interfacial
reactions, namely, the thickness and morphology of the intermetallic layers, which are correlated with the shear strength
of the solder joint as well as its electrical resistance. A model joint was made by joining two “L-shaped” copper coupons
with three Pb-free solders, Sn-3.5Ag (SA), Sn-3.8Ag-0.7Cu (SAC), and Sn-3.5Ag-3Bi (SAB) (all in wt.%), and combined with two
surface finishes, Cu and Ni(P)/Au. The thickness and morphology of the intermetallic compounds (IMCs) formed at the interface
were affected by solder composition, solder volume, and surface finish. The mechanical and electrical properties of Pb-free
solder joints were evaluated and correlated with their interfacial reactions. The microstructure of the solder joints was
also investigated to understand the electrical and mechanical characteristics of the Pb-free solder joints. 相似文献
13.
Effect of rare earth element additions on the microstructure and mechanical properties of tin-silver-bismuth solder 总被引:2,自引:0,他引:2
Zhidong Xia Zhigang Chen Yaowu Shi Nan Mu Na Sun 《Journal of Electronic Materials》2002,31(6):564-567
There are numerous intermetallic compounds (IMCs) with various shapes in a tin-silver-bismuth solder alloy. These IMCs can
affect the mechanical properties of the solder and, therefore, the reliability of the joints. In this study, minimal rare
earth elements added into the solder were adsorbed at the grain boundary of IMCs. This adsorption behavior changed the relationship
between growth velocities of the various crystalline directions of the IMC polycrystalline, which resulted in finer particles
and more uniform distribution of the IMC phase. The average size of IMC particles decreased from 0.20 μm to 0.12 μm, while
their average distance decreased from 1.25 μm to 0.65 μm. These fine IMC particles made the alloy stronger and more ductile
through dispersion strengthening. 相似文献
14.
Polina Snugovsky Heather McCormick Simin Bagheri Zohreh Bagheri Craig Hamilton Marianne Romansky 《Journal of Electronic Materials》2009,38(2):292-302
The results of an intensive reliability study on Pb-free ball grid array (BGA)/Sn-Pb solder assemblies as well as some lessons
learnt dealing with mixed assembly production at Celestica are described in this paper. In the reliability study, four types
of Pb-free ball grid array components were assembled on test vehicles using the Sn-Pb eutectic solder and typical Sn-Pb reflow
profiles with 205°C to 220°C peak temperatures. Accelerated thermal cycling (ATC) was conducted at 0°C to 100°C. The influence
of the microstructure on Weibull plot parameters and the failure mode will be shown. Interconnect defects such as nonuniform
phase distribution, low-melting structure accumulation, and void formation are discussed. Recommendations on mixed assembly
and rework parameters are given. 相似文献
15.
Microstructural modifications and properties of Sn-Ag-Cu solder joints induced by alloying 总被引:1,自引:0,他引:1
I. E. Anderson B. A. Cook J. Harringa R. L. Terpstra 《Journal of Electronic Materials》2002,31(11):1166-1174
Slow cooling (1–3°C/sec) of Sn-Ag-Cu and Sn-Ag-Cu-X (X = Fe, Co) solder-joint specimens, made by hand soldering, simulated
reflow in a surface-mount assembly to achieve similar as-solidified joint microstructures for realistic shear-strength testing,
using Sn-3.5Ag (wt.%) as a baseline. Consistent with predictions from a recent Sn-Ag-Cu ternary phase-diagram study, either
Sn dendrites, Ag3Sn primary phase, or Cu6Sn5 primary phase were formed during solidification of joint samples made from the selected near-eutectic Sn-Ag-Cu alloys. Minor
substitution of Co for Cu in Sn-3.7Ag-0.9Cu refined the joint-matrix microstructure by an apparent catalysis effect on the
Cu6Sn5 phase, whereas Fe substitution promoted extreme refinement of the Sn-dendritic phase. Ambient-temperature shear strength
was reduced by Sn dendrites in the joint microstructure, especially coarse dendrites in solute poor Sn-Ag-Cu, e.g., Sn-3.0Ag-0.5Cu,
while Sn-3.7Ag-0.9Cu with Co and Fe additions have increased shear strength. At elevated (150°C) temperature, no significant
difference exists between the maximum shear-strength values of all of the alloys studied. 相似文献
16.
The microstructures of the Sn-Zn-Al lead-free solders have been investigated using scanning electron microscopy. The Al and
Zn contents of the solders investigated were 0.45%∼4.5% and 8.55%∼85.5%, respectively. The solders were prepared from the
Zn-5Al master alloy and Sn. The precipitates formed in these solders were analyzed for their compositions with energy dispersive
spectroscopy. The eutectic temperature and the transition temperatures of these solders upon cooling were identified with
cooling curves as well as with differential scanning calorimetry. 相似文献
17.
Thermodynamics of the Sn-In-Ag solder system 总被引:3,自引:0,他引:3
18.
C. Y. Liu Jian Li G. J. Vandentop W. J. Choi K. N. Tu 《Journal of Electronic Materials》2001,30(5):521-525
The wetting behavior of SnAg based Pb-free solders on Cu and Cu substrates plated with Au, Pd, and Au/Pd thin films have been
studied. The wetting angle and kinetics of interfacial reaction were measured. The Au-plated substrates exhibit better wetting
than the Pd-plated substrates. In the case of SnAg on Pd-plated Cu, SEM observation revealed that the solder cap was surrounded
by an innerring of Cu−Sn compound and an outer ring of Pd−Sn compound. This implies that the molten SnAg solder had removed
the Pd and wetted the Cu directly in the equilibrium state. The effects of pre-doping Cu in the SnAg solder on wetting behavior
were also investigated. We found that wettability decreases with increasing Cu content in the solder. We also observed that
the SnAgCu solders have a lower Cu consumption rate than the SnAg solder. 相似文献
19.
The shear strength behavior and microstructural effects after aging for 100 h and 1,000 h at 150°C are reported for near-eutectic
Sn-Ag-Cu (SAC) solder joints (joining to Cu) made from Sn-3.5Ag (wt.%) and a set of SAC alloys (including Co- and Fe-modified
SAC alloys). All joints in the as-soldered and 100-h aged condition experienced shear failure in a ductile manner by either
uniform shear of the solder matrix (in the strongest solders) or by a more localized shear of the solder matrix adjacent to
the Cu6Sn5 interfacial layer, consistent with other observations. After 1,000 h of aging, a level of embrittlement of the Cu3Sn/Cu interface can be detected in some solder joints made with all of the SAC alloys and with Sn-3.5Ag, which can lead to
partial debonding during shear testing. However, only ductile failure was observed in all solder joints made from the Co-
and Fe-modified SAC alloys after aging for 1,000 h. Thus, the strategy of modifying a strong (high Cu content) SAC solder
alloy with a substitutional alloy addition for Cu seems to be effective for producing a solder joint that retains both strength
and ductility for extended isothermal aging at high temperatures. 相似文献
20.
This paper reports on the microstructure-creep property relationship of three precipitation-strengthened tin (Sn)-based lead
(Pb)-free solder alloys (Sn-0.7Cu, Sn-3.5Ag, and Sn-3.8Ag-0.7Cu) in bulk samples, together with Sn-37Pb as the alloy for comparison
at temperatures of 303 K, 348 K, and 393 K. The creep resistance of these three Sn-based Pb-free solders increases, i.e.,
the steady-state creep rates decrease, with increasing volume fraction of precipitate phases for the Pb-free solder alloys.
Their apparent stress exponents (na ∼ 7.3-17), which are all higher than that of pure Sn, attain higher values with increasing volume fraction of precipitate
phases at constant temperature, and with decreasing temperature for the same solder alloy. 相似文献