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1.
Liang Zhang Song-bai Xue Li-li Gao Zhong Sheng Huan Ye Zheng-xiang Xiao Guang Zeng Yan Chen Sheng-lin Yu 《Journal of Materials Science: Materials in Electronics》2010,21(1):1-15
Sn–Zn solder alloys have been considered as one of the more attractive lead-free solders since it can easily replace Sn–Pb
eutectic alloy without increasing the soldering temperature. However, there are still some problems to be resolved, such as
the argument about the poor oxidation resistance and embrittlement behavior. In order to overcome these drawbacks, and further
enhance the properties of Sn–Zn lead-free solder alloys, a small amount of alloying elements (rare earths, Bi, Ag, Al, Ga,
In, Cr, Cu, Sb, Ni, Ge) added into Sn–Zn alloys were selected by many researchers. For example, a small amount of Al, P, Bi,
Ga can improve the high-temperature oxidation resistance of Sn–Zn solders remarkably as well as Cr. This paper summarizes
the effects of alloying elements on the wettability, oxidation resistance, melting behavior, mechanical properties, creep
properties, microstructures and intermetallic compounds layer of Sn–Zn lead-free solders. 相似文献
2.
X. P. Zhang L. M. Yin C. B. Yu 《Journal of Materials Science: Materials in Electronics》2008,19(4):393-398
In our previous study, the creep behavior of the lead-free Sn–Ag–Cu–Bi solder joints has been proven to follow the Arrhenius
power-law relationship, and the thermal fatigue behavior of the solder joints exhibits the typical creep deformation characteristics
with a superposition of the pulsating features. In this study, the thermal creep and fracture behaviors of the lead-free Sn–Ag–Cu–Bi
solder interconnections were characterized under different stress levels, with a systematical comparison to that of a traditional
Sn60Pb40 near-eutectic solder. The results show that the creep strain rate of both solder connections follows Weertman-Dorn
equation, and the calculated creep stress exponent for two solders is reasonably close to other published data. The SEM inspection
and analysis of fractographies of creep fractured solder joints manifest that the creep failure of the lead-free Sn–Ag–Cu–Bi
solder joint shows obviously intergranular fracture mechanism, while the Sn60Pb40 joint ruptures dominantly by a transgranular
sliding mechanism. 相似文献
3.
X. P. Zhang C. B. Yu S. Shrestha L. Dorn 《Journal of Materials Science: Materials in Electronics》2007,18(6):665-670
Creep and fatigue behaviors of the interconnections soldered by the lead-free Sn–Ag–Cu–Bi solder were investigated at different
elevated temperatures (with the homologue temperature in the range of 0.71– 0.82), with a comparison to that of a traditional
Sn60Pb40 solder. The results show that the lead-free Sn–Ag–Cu–Bi solder shows a superior anti-creep performance over the Sn60Pb40
solder, in terms of a much lower creep strain rate and a vastly elongated creep fracture lifetime; in the secondary creep
regime, the calculated creep-activation energy for two solders is reasonably close to other published data. In addition, it
has also been shown that the joints soldered by the lead-free Sn–Ag–Cu–Bi solder exhibits a superb fatigue property. 相似文献
4.
Changdong Zou Yulai Gao Bin Yang Qijie Zhai 《Journal of Materials Science: Materials in Electronics》2010,21(9):868-874
The traditional Sn–Pb eutectic solder alloys are being phased out from the electronics industry due to the toxicity of lead
(Pb), leading to the development and implementation of lead-free solders. Sn3.5Ag lead-free solder alloy, considered to be
one of the promising alternatives to replace the traditionally used Sn–Pb solder, however, still has some weaknesses, such
as its higher melting temperature than that of the Sn–Pb solder alloy. A possible way to decrease the melting temperature
of a solder alloy is to decrease the alloy particle size to the nanometer range. Sn3.5Ag nanoparticles with different size
distribution were synthesized using chemical reduction method by applying NaBH4 as reduction agent. The melting properties of these synthesized nanoparticles were studied by differential scanning calorimetry
(DSC), and size-dependent melting temperature depression of these nanoparticles has been observed. Gibbs–Thomson equation
was used to analyze the size-dependent melting temperature property, giving a good prediction of the melting temperature depression
for the Sn-based lead-free solder alloy nanoparticles. 相似文献
5.
Iver E. Anderson 《Journal of Materials Science: Materials in Electronics》2007,18(1-3):55-76
The global electronic assembly community is striving to accommodate the replacement of Pb-containing solders, primarily Sn–Pb
alloys, with Pb-free solders due to environmental regulations and market pressures. Of the Pb-free choices, a family of solder
alloys based on the Sn–Ag–Cu (SAC) ternary eutectic (T
eut. = 217°C) composition have emerged with the most potential for broad use across the industry, but the preferred (typically
near-eutectic) composition is still in debate. This review will attempt to clarify the characteristic microstructures and
mechanical properties of the current candidates and recommend alloy choices, a maximum operating temperature limit, and directions
for future work. Also included in this review will be an exploration of several SAC + X candidates, i.e., 4th element modifications
of SAC solder alloys, that are intended to control solder alloy undercooling and solidification product phases and to improve
the resistance of SAC solder joints to high temperature thermal aging effects. Again, preliminary alloy recommendations will
be offered, along with suggestions for future work. 相似文献
6.
F. Tai F. Guo Z. D. Xia Y. P. Lei Y. W. Shi 《Journal of Materials Science: Materials in Electronics》2010,21(7):702-707
In this research, the typical nano-structured Polyhedral Oligomeric Silsesquioxane (POSS) particles were incorporated into
the Sn–3.5Ag eutectic solder paste by mechanically mixing to form lead-free composite solder. The effects of nano-structured
POSS additions on the microstructure and mechanical properties of as-fabricated composite solder alloys were systematically
investigated. Experimental results indicated that the average size and spacing distance of Ag3Sn intermetallic compounds (IMCs) in composite solder matrix decreased as compared to the Sn–3.5Ag eutectic solder. The 3 wt%
addition of nano-structured POSS particles could enhance the microhardness of composite solder by 18.4% compared with the
Sn–3.5Ag eutectic solder matrix. The average grain size and spacing distance of Ag3Sn IMCs in Sn–Ag + 3 wt% POSS composite solder matrix reduced from 0.35 to 0.23 μm and from 0.54 to 0.32 μm, respectively.
The refined Ag3Sn IMCs, acting as a strengthening phase in the solder matrix, could enhance the microhardness of the composite solders. 相似文献
7.
Even though several EMS (Electronic manufacturing services) companies are currently producing “lead free” products, a general
notion of apprehension still exists in the industry, primarily due to the lack of sufficient mechanical reliability data supporting
the use of lead free alloys. The current study was an effort to generate an understanding of the mechanisms of creep deformation
in monolithic and composite (Ag and Cu reinforced) Sn–3.5Ag and Sn–3.0Ag–0.5Cu lead free alloys in the high stress high temperature
regime. Small volume solder samples were reflowed using a custom built computer controlled resistance furnace. Impression
creep testing was employed to determine the activation energy and stress exponent. A careful analysis of the collected data
revealed the underlying creep mechanisms and the following conclusions could be made. Both Sn–3.5Ag and Sn–3.0Ag–0.5Cu exhibited
higher creep resistance as compared to the eutectic tin–lead solder under all tested conditions, with the ternary lead free
alloy marginally outperforming the binary lead free alloy. Composite solders performed better as compared to monolithic solders.
Furthermore, Cu reinforced solders demonstrated higher creep resistance as compared to Ag reinforced solders. 相似文献
8.
Mingna Wang Jianqiu Wang Hao Feng Wei Ke 《Journal of Materials Science: Materials in Electronics》2012,23(1):148-155
The heterogeneous microstructure of solder could be obtained when cooling rate of the solder joint was not even, which would
affect the corrosion behavior of solder during service. The ambient temperature would also affect the corrosion behavior of
solder joint. In this paper, the effects of microstructure and temperature on the corrosion behavior of Sn–3.0Ag–0.5Cu (SAC305)
lead-free solder were investigated. The various microstructures of SAC305 lead-free solder were obtained by cooling specimens
in air and furnace. Compared to the fine-fibrous Ag3Sn phase inside the commercial SAC305 solder, platelet-like Ag3Sn formed as cooling speed decreasing. The polarization behavior of SAC305 solders in 3.5 wt.% NaCl solution was not significantly
affected by various microstructures, but sensitive to temperature. 相似文献
9.
Ikuo Shohji Tomohiro Yoshida Takehiko Takahashi Susumu Hioki 《Journal of Materials Science: Materials in Electronics》2004,15(4):219-223
The tensile properties of Sn–8 mass % Zn–3 mass % Bi and Sn–58 mass % Bi low-melting lead-free solders were investigated and compared with those of a Sn–Pb eutectic solder. The tensile strength decreases with decreasing strain rate and increasing temperature. The tensile strength of each solder is approximately double that of the Sn–Pb solder at room temperature (RT). The ductility of each solder is inferior to that of the Sn–Pb solder. From the results of strain-rate-change tests, the stress exponents and the activation energies for creep of Sn–58Bi and Sn–8Zn–3Bi were also examined. 相似文献
10.
The characterization of lead-free solders, especially after isothermal aging, is very important in order to accurately predict
the reliability of solder joints. However, due to lack of experimental testing standards and the high homologous temperature
of solder alloys (T
h > 0.5T
m even at room temperature), there are very large discrepancies in both the tensile and creep properties provided in current
databases for both lead-free and Sn–Pb solder alloys. Some recent researches show that the room temperature aging has significant
effects on mechanical properties of solders. This paper is intended to review all available data in the field and give rise
to the possible factors including room temperature effects which causes the large discrepancies of data. This review of the
research literatures has documented the dramatic changes that occur in the constitutive and failure behavior of solder materials
and solder joint interfaces during isothermal aging. However, these effects have been largely ignored in most previous studies
involving solder material characterization or finite element predictions of solder joint reliability during thermal cycling.
It is widely acknowledged that the large discrepancies in measured solder mechanical properties from one study to another
arise due to differences in the microstructures of the tested samples. This problem is exacerbated by the aging issue, as
it is clear that the microstructure and material behavior of the samples used in even a single investigation are moving targets
that change rapidly even at room temperature. Furthermore, the effects of aging on solder behavior must be better understood
so that more accurate viscoplastic constitutive equations can be developed for SnPb and SAC solders. Without such well-defined
relationship, it is doubtful that finite element reliability predictions can ever reach their full potential. 相似文献
11.
W. H. Zhong Y. C. Chan B. Y. Wu M. O. Alam J. F. Guan 《Journal of Materials Science》2007,42(13):5239-5247
This paper evaluates the shearing behavior of ball grid array (BGA) solder joints on Au/Ni/Cu pads of FR4 substrates after
multiple reflow soldering. A new Pb-free solder, Sn–3Ag–0.5Cu–8In (SACI), has been compared with Sn–3Ag–0.5Cu (SAC) and Sn–37Pb
(SP) solders, in terms of fracture surfaces, shearing forces and microstructures. Three failure modes, ball cut, a combination
of solder shear and solder/pad bond separation, and pad lift, are assessed for the different solders and reflow cycles. It
is found that the shearing forces of the SP and SAC solder joints tend to increase slightly with an increase in the number
of reflow cycles due to diffusion-induced solid solution strengthening of the bulk solder and augmentation of the shearing
area. However, the shearing forces of the SACI solder joints decrease slightly after four cycles of reflow, which is ascribed
to the thermal degradation of both the solder/intermetallic compound (IMC) and IMC/Ni interfaces. The SACI solder joints yield
the highest strengths, whereas the SP solder joints give the smallest values, irrespective of the number of reflow cycles.
Thickening of the interfacial IMC layer and coarsening of the dispersing IMC particles within the bulk solders were also observed.
Nevertheless, the variation of shearing forces and IMC thickness with different numbers of reflow cycles was not so significant
since the Ni under layer acted as an effective diffusion barrier. In addition, the initially-formed IMC layer retarded the
further extensive dissolution of the pad material and its interaction with the solder. 相似文献
12.
Liang Zhang Song-bai Xue Li-li Gao Zhong Sheng Guang Zeng Yan Chen Sheng-lin Yu 《Journal of Materials Science: Materials in Electronics》2010,21(6):635-642
For quad flat packages (QFP256), lead-free soldered joints reliability in service is a critical issue. In this paper, soldering
experiments of quad flat package (QFP256) devices were carried out by means of infrared reflow soldering system with Sn–3.8Ag–0.7Cu
and Sn–3.8Ag–0.7Cu–0.03Ce lead-free solders, respectively, and the mechanical properties of micro-joints of the QFP devices
were tested and studied by STR micro-joints tester. The results indicate that the tensile strength of Sn–Ag–Cu–Ce soldered
joints is better than that of Sn–Ag–Cu soldered joints. In particular, the addition of trace Ce to the Sn–Ag–Cu solder can
refine the microstructures and decrease the thickness of the intermetallic compound layer of Sn–Ag–Cu solder alloys. In addition,
the stress–strain response of Sn–Ag–Cu/Sn–Ag–Cu–Ce soldered joints in quad flat packaging was investigated using finite element
method based on Garofalo–Arrhenius model. The simulated results indicate creep distribution of soldered joints is not uniform,
the heel and toe of soldered joints, the area between soldered joints and leads are the creep concentrated sites. The creep
strain of Sn–Ag–Cu–Ce soldered joints is lower than that of Sn–Ag–Cu soldered joints. 相似文献
13.
Changdong Zou Yulai Gao Bin Yang Qijie Zhai 《Journal of Materials Science: Materials in Electronics》2012,23(1):2-7
The Sn3.0Ag0.5Cu (wt%) lead-free solder alloy is considered to be one of the most promising alternatives to replace the traditionally
used Sn–Pb solders. This alloy composition possesses, however, some weaknesses, mainly as a result of its higher melting temperature
compared to the eutectic Sn–Pb solders. Nanoparticles of Sn3.0Ag0.5Cu lead-free solder alloy nanoparticles were prepared by
chemical reduction with NaBH4 as a reducing agent at room temperature. The melting temperature of the synthesized Sn3.0Ag0.5Cu alloy nanoparticles was
determined by differential scanning calorimetry (DSC). The results showed that the calorimetric onset melting temperature
of the Sn3.0Ag0.5Cu alloy nanoparticles could be as low as 200 °C, which was about 17 °C lower than that of the bulk alloy
(217 °C). The field emission scanning electron microscopy (SEM) images of the as-prepared nanoparticles indicated that the
major particle size of Sn3.0Ag0.5Cu nanoparticles is smaller than 50 nm. The structure and morphology of the nanoparticles
were analyzed with high resolution transmission electron microscopy (HRTEM). The Ag3Sn and Sn phase were observed in the HRTEM
images, which was in good agreement with the XRD results. These low melting temperature Sn3.0Ag0.5Cu alloy nanoparticles show
a potential to manufacture high quality lead-free solders for electronic products. 相似文献
14.
Wen Xue Chen Song Bai Xue Hui Wang Jian Xin Wang Zong Jie Han Li Li Gao 《Journal of Materials Science: Materials in Electronics》2010,21(5):461-467
The microstructures, wettabilities and mechanical properties of Sn–9Zn–xAg (x = 0, 0.1, 0.3, 0.5, 1 wt%) lead-free solders were investigated, respectively in this paper. Results show that, when the quantity
of Ag added to the solder is 0.3 wt%, the microstructure of the solder becomes finer and more uniform than Sn–9Zn, and when
the quantity of Ag is exceeded 0.3 wt% (upto 0.5–1 wt%), the AgZn3 intermetallic compounds appear in the solder. In particular, adding 0.3 wt% Ag improves the wettability due to the better
oxidation resistance of the Sn–9Zn–0.3Ag solder. Results also indicate that adding 0.3 wt% Ag to the solder enhances mechanical
property of soldered joint, at which the fracture micrographs show that plenty of small and uniform dimples could be observed
on the Sn–9Zn–0.3Ag soldered joints fractures. When the content of Ag is upto 1 wt%, some Cu–Zn and Ag–Zn intermetallic compounds
appear on the bottom of dimples, and the mechanical property of the soldered joint decreases. 相似文献
15.
C. Wei Y. C. Liu J. B. Wan 《Journal of Materials Science: Materials in Electronics》2009,20(9):861-866
The structural evolution of interfaces between the Sn–3.5Ag–0.9Zn–xAl (x = 0.5 and 1.0) solders and Cu substrate has been investigated by microstructural observations. The results suggest that the
addition of Al in the Sn–3.5Ag–0.9Zn restrains the formation of Cu5Zn8 intermetallic compounds (IMCs) at the soldered interface. Moreover, the formation of Al2Cu and Cu9Al4 IMCs leads to a crack failure near the interface of the Sn–3.7Ag–0.9Zn–1Al and Cu pad. It is suggested that the increase
of Al content (e.g. 1 wt%) in the Sn–Ag–Zn eutectic solder would do harm to the reliability of the solder joint. 相似文献
16.
Rare-earth additions to lead-free electronic solders 总被引:5,自引:0,他引:5
The research in lead(Pb)-free solder alloy has been a popular topic in recent years, and has led to commercially available
Pb-free alloys. Further research in certain properties to improve aspects such as manufacturability and long term reliability
in many Pb-free alloys are currently undertaken. It was found by researchers that popular Pb-free solders such as Sn–Ag, Sn–Cu,
Sn–Zn and Sn–Ag–Cu had improved their properties by doping with trace amounts of rare earth (RE) elements. The improvements
include better wettability, creep strength and tensile strength. In particular, the increase in creep rupture time in Sn–Ag–Cu–RE
was 7 times, when the RE elements were primarily Ce and La. Apart from these studies, other studies have also shown that the
addition of RE elements to existing Pb-free could make it solderable to substrates such as semiconductors and optical materials.
This paper summarizes the effect of RE elements on the microstructure, mechanical properties and wetting behavior of certain
Pb-free solder alloys. It also demonstrates that the addition of RE elements would improve the reliability of the interconnections
in electronic packaging. For example, when Pb-free-RE alloys were used as solder balls in a ball grid array (BGA) package,
the intermetallic compound layer thickness and the amount of interfacial reaction were reduced. 相似文献
17.
《Materials Science & Technology》2013,29(12):1467-1473
AbstractWith the development and use of a variety of Pb free solders, it is probable that some solder joints in electronic assemblies may be made with solders of two different compositions. To investigate possible microstructures resulting from such procedure, samples were prepared using small balls of four different Sn–Ag–Cu (SAC) Pb free solders, as well as Sn–Zn–Al solder, melted together with eutectic Pb–Sn solder paste and also various SAC solder pastes, on a copper substrate. It was observed that using eutectic Pb–Sn solder paste with an SAC solder ball introduced some Pb–Sn eutectic microstructure and changed the ternary eutectic present from Ag3Sn–Cu6Sn5–Sn to Ag3Sn–Pb–Sn. Use of an SAC solder paste with Sn–Zn–Al solder introduced an apparent Ag–Cu–Zn ternary compound, replacing Zn lamellae of the Sn–Zn eutectic. With eutectic Pb–Sn solder paste, the Pb–Sn–Zn ternary eutectic was formed. It was noted that use of a high Sn solder results in rapid dissolution of the copper substrate. 相似文献
18.
Changqing Liu Zhiheng Huang Paul P. Conway Rachel C. Thomson 《Journal of Materials Science》2007,42(11):4076-4086
The paper compares theoretical calculations with experimental data, to identify the metallurgical mechanisms with respect
to the rework or repair that may be encountered in the transition period from Sn–Pb to Pb-free soldering. Thermodynamic calculations
have been carried out to study material behaviour and possible formation of intermetallic precipitates during the reaction
between Sn–Pb and Sn–Ag–Cu Pb-free alloys. Two Sn–Ag–Cu alloys that are relevant to current industrial interests, namely Sn–3.9Ag–0.6Cu*
(known as ‘405 alloy’ in Europe and North America), and Sn–3.0Ag–0.5Cu (known as ‘305’ alloy in Asia), were reacted with different
contamination levels of eutectic Sn–37Pb solder. The variables examined included those related to both the materials and processes,
such as composition, temperature and cooling rate. Together these are the primary drivers with respect to the resultant solder
microstructures, which were studied using scanning electron microscopy (SEM). Nanoindentation, which is suitable for the ultra-fine
and complex microstructures, was also used to investigate the micromechanical properties, including hardness and elastic modulus,
at both ambient and elevated temperatures. The results from this work provide guidance as to the consequence for microstructural
evolution and hence mechanical integrity when small amounts of Pb exist in Pb-free alloys.
The composition of alloys in this paper is in weight percentage (wt%) 相似文献
19.
Wenxue Chen Songbai Xue Hui Wang Jianxin Wang Zongjie Han 《Journal of Materials Science: Materials in Electronics》2010,21(5):496-502
The influences of different Ga content on the properties of Sn–9Zn lead-free solder were investigated. The results indicate
that Ga plays an important role not only in the structure and melting behavior, but also in the solderability and mechanical
property. Sn–9Zn–0.5Ga shows finer and more uniform microstructure than Sn–9Zn. With the addition of low-melting-point Ga,
TL (liquidus temperature) and TS (solidus temperature) of the alloys decreases with increasing of Ga content while △T (liquidus
temperature minus solidus temperature) increases. Ga can improve the oxidation resistance and reduce the surface tension of
solder, so the solderability of Sn–9Zn–xGa lead-free solder is significantly improved. When the content of Ga is 0.5 wt.%, the pull force of soldered joint is 16.1 N,
enhanced by 11% compared to that of Sn–9Zn, and the fracture micrographs show that the joint failed in a ductile manner. The
addition of 3 wt.%Ga resulted in a brittle failure. The introduction of 0.5 wt.% Ga into Sn–9Zn alloy improves creep resistance
of the solder. 相似文献
20.
Yaowu Shi Jianping Liu Zhidong Xia Yongping Lei Fu Guo Xiaoyan Li 《Journal of Materials Science: Materials in Electronics》2008,19(4):349-356
In the present work the creep properties of Sn37Pb and Sn0.7Cu based composite solders with nano-sized metallic Cu, Ag and
nano-sized oxide Al2O3, TiO2 reinforcement particles have been studied. First, a series of volume percentages of reinforcements were selected for optimizing
the content of particles. Then, the composite solder with optimum volume fraction of the reinforcement particles, corresponding
to maximum creep rupture life, is selected for investigating the effect of applied stress level and test temperature on creep
rupture life of the composite solder joints. In the creep rupture life test, small single-lap tensile-shear joints were adopted.
The results indicate that all the composite solders have improved creep resistance, comparing to the eutectic Sn37Pb solder
and the Sn0.7Cu lead-free solder. The creep rupture life of the composite solder joints is first increased with the increase
in the volume fraction of reinforcement in the composite solders. Then, the creep rupture life is decreased, as the reinforcement
content exceeds a certain value. The creep rupture life of the solder joints is decreased with the increase of applied stress
and testing temperature. Moreover, the reinforced efficiency of nano-sized Ag particles is the best in all the tested nano-sized
reinforcements for the Sn37Pb based and Sn0.7Cu based composite solders, when the particles contents are in their own optimum
content. 相似文献