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1.
The reaction between the Sn-Ag-Cu solders and Ni at 250°C for 10 min and 25 h was studied. Nine different Sn-Ag-Cu solders,
with the Ag concentration fixed at 3.9 wt.% and Cu concentrations varied between 0.0–3.0 wt.%, were used. When the reaction
time was 10 min, the reactions strongly depended on the Cu concentration. At low-Cu concentrations (≦0.2 wt.%), only a continuous
(Ni1−xCux)3Sn4 layer formed at the interface. When the Cu concentration increased to 0.4 wt.%, a continuous (Ni1−xCux)3Sn4 layer and a small amount of discontinuous (Cu1−yNiy)6Sn5 particles formed at the interface. When the Cu concentration increased to 0.5 wt.%, the amount of (Cu1−yNiy)6Sn5 increased and (Cu1−yNi6)6Sn5 became a continuous layer. Beneath this (Cu1−yNiy)6Sn5 layer was a very thin but continuous layer of (Ni1−xCux)3Sn4. At higher Cu concentrations (0.6–3.0 wt.%), (Ni1−xCux)3Sn4 disappeared, and only (Cu1−yNiy)6Sn5 was present. The reactions at 25 h also depended strongly on the Cu concentration, proving that the strong concentration
dependence was not a transient phenomenon limited to a short reaction time. The findings of this study were rationalized using
the Cu-Ni-Sn isotherm. This study shows that precise control over the Cu concentration in solders is needed to produce consistent
results. 相似文献
2.
Excessive intermetallic compound (IMC) growth in solder joints will significantly decrease the reliability of the joints.
IMC growth is known to be influenced by numerous factors during the component fabrication process and in service. It is reported
that, other than temperature and holding time, stress can also influence the IMC growth behavior. However, no existing method
can be used to study the effect of stress state on IMC growth in a controlled manner. This paper presents a novel method to
study the effect of stress on interfacial IMC growth between Sn-Ag-Cu solder and a Cu substrate coated with electroless Ni
immersion Au (ENIG). A C-ring was used and in-plane bending induced tensile and compressive stresses were applied by tightening
the C-ring. Results revealed that in-plane compressive stress led to faster IMC growth as compared with in-plane tensile stress. 相似文献
3.
4.
Trace amounts of La were utilized to improve the melting behaviors, microstructures, tensile properties and microhardness of Sn-3.0Ag-0.5Cu lead-free solder alloy. La has little effect on the melting behavior of Sn-3.0Ag-0.5Cu alloy according to the differential thermal analysis (DTA) tests. The X-ray diffraction (XRD) patterns show that β-Sn, Ag3Sn and Cu6Sn5 coexist in the as-cast solder alloys and LaSn3 phases emerge when adding 0.4% La. The microstructures modified by La are more uniform and much finer than that of baseline alloy, and the coarse LaSn3 particles with complex dendrites are observed by optical microscopy (OM) and scanning electron microscopy (SEM) when the addition of La is up to 0.4%. The composition of the LaSn3 phases is identified by energy-dispersive spectroscopy (EDS). There are considerable improvements in mechanical properties with 0.05% and 0.1% addition, but degenerations by adding 0.4%La. The Vickers microhardness of β-Sn and eutectic area are both enhanced with the addition of La and the microhardness of LaSn3 is much larger than those of β-Sn and eutectic area. 相似文献
5.
对锡银铜系高可靠性焊料合金的研究虽然已经较为广泛,但是缺乏对其焊点在不同应变速率下的剪切强度和断裂模式的研究。本文将牌号为SAC305和Innolot不同成分的锡银铜系焊料合金锡膏印刷在镍金镀层(Ni(P)/Au)上回流成BGA焊点,采用DAGE 4000 HS焊接强度测试仪进行不同剪切速率下的剪切性能测试,并对其剪切曲线、剪切强度及断裂能进行计算和分析,再采用金相显微镜和扫描电子显微镜(SEM)对焊点界面微观结构及断口进行表征分析。结果表明:合金本身成分的差异导致焊点界面金属间化合物层(IMC层)厚度和分布存在差异,随着剪切速率的增加,SAC305和Innolot合金焊点的强度总体上都随之增加,且焊点的断裂模式由焊点基体内部的韧性断裂向界面金属间化合物脆性断裂发生转变,Innolot合金由于其他金属元素添加导致的强化作用使得其剪切强度得到较大提升而塑性损伤。 相似文献
6.
Sung K. Kang Donovan Leonard Da-Yuan Shih Lynne Gignac D. W. Henderson Sungil Cho Jin Yu 《Journal of Electronic Materials》2006,35(3):479-485
The near-ternary eutectic Sn-Ag-Cu alloys have been identified as leading Pb-free solder candidates to replace Pb-bearing
solders in microelectronic applications. However, recent investigations on the processing behavior and solder joints reliability
assessment have revealed several potential reliability risk factors associated with the alloy system. The formation of large
Ag3Sn plates in Sn-Ag-Cu joints, especially when solidified in a relatively slow cooling rate, is one issue of concern. The implications
of large Ag3Sn plates on solder joint performance and several methods to control them have been discussed in previous studies. The minor
Zn addition was found to be effective in reducing the amount of undercooling required for tin solidification and thereby to
suppress the formation of large Ag3Sn plates. The Zn addition also caused the changes in the bulk microstructure as well as the interfacial reaction. In this
paper, an in-depth characterization of the interfacial reaction of Zn-added Sn-Ag-Cu solders on Cu and Au/Ni(P) surface finishes
is reported. The effects of a Zn addition on modification of the interfacial IMCs and their growth kinetics are also discussed. 相似文献
7.
雾化介质对无铅焊锡粉末形貌及粒度分布的影响 总被引:1,自引:0,他引:1
利用自行设计的超音速雾化制粉装置,研究不同雾化介质对SnAgCu系无铅焊锡粉末有效雾化率、粒度分布及球形度的影响。结果表明:在一定雾化条件下,氦气雾化粉末具有最高的有效雾化率,最佳的球形度、表面光滑度及粒度分布;氮气雾化的粉末具有较好的综合性能;与氦气、氮气相比,氩气雾化粉末综合性能较差;空气雾化粉末雾化率较高,但粉末较粗、表面粗糙。 相似文献
8.
Effect of silver content on thermal fatigue life of Sn-xAg-0.5Cu flip-chip interconnects 总被引:5,自引:0,他引:5
Shinichi Terashima Yoshiharu Kariya Takuya Hosoi Masamoto Tanaka 《Journal of Electronic Materials》2003,32(12):1527-1533
The thermal fatigue properties of Sn-xAg-0.5Cu (x=1, 2, 3, and 4 in mass%) flip-chip interconnects were investigated to study
the effect of silver content on thermal fatigue endurance. The solder joints with lower silver context (x=1 and 2) had a greater
failure rate compared to those with higher silver content (x=3 and 4) in thermal fatigue testing. Cracks developed in the
solders near the solder/chip interface for all joints tested. This crack propagation may be mainly governed by the nature
of the solders themselves because the strain-concentrated area was similar for tested alloys independent of the silver content.
From the microstructural observation, the fracture was a mixed mode, transgranular and intergranular, independent of the silver
content. Higher silver content alloys (x=3 and 4) had finer Sn grains before thermal cycling according to the dispersion of
the Ag3Sn intermetallic compound, and even after the cycling, they suppressed microstructural coarsening, which degrades the fatigue
resistance. The fatigue endurance of the solder joints was strongly correlated to the silver content, and solder joints with
higher silver content had better fatigue resistance. 相似文献
9.
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
10.
Paul T. Vianco Jerome A. Rejent Alice C. Kilgo 《Journal of Electronic Materials》2004,33(11):1389-1400
The compression creep behavior was studied for the ternary solder alloy 95.5Sn-3.9Ag-0.6Cu in the as-cast condition. Samples
were tested under stresses of 2–45 MPa and temperatures of −25–160°C. There was a significant variability in the creep curve
shape, strain magnitude, and steady-state strain-rate properties. A multivariable linear-regression analysis of the steady-state
strain-rate data, using the sinh-law stress representation, indicated two mechanisms distinguished by low- and high-temperature
regimes of −25–75°C and 75–160°C, respectively. The sinh-law stress exponent (n) and apparent-activation energy (ΔH) in the
−25–75°C regime were 4.4 ± 0.7 kJ/mol and 25 ± 7 kJ/mol (63% confidence intervals), respectively. Those same parameters in
the 75–160°C regime were 5.2±0.8 kJ/mol and 95±14 kJ/mol, respectively, for the high-temperature regime. The values of ΔH
suggested a short-circuit diffusion mechanism at low temperatures and a lattice or bulk-diffusion mechanism at high temperatures.
The stress dependency of the steady-state strain rate did not indicate a strong power-law breakdown behavior or a threshold
stress phenomenon. Cracks and grain-boundary sliding were not observed in any of the samples. As the creep temperature increased,
a coarsened particle boundary and particle depletion zone formed in the region of fine Ag3Sn particles that existed between the Sn-rich phase areas. The coarsened particle boundary, as well as accelerated coarsening
of Ag3Sn particles, were direct consequences of the creep deformation process. 相似文献