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1.
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
2.
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
3.
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
4.
Sinn-Wen Chen Chao-Hong Wang Shih-Kang Lin Chen-Nan Chiu 《Journal of Materials Science: Materials in Electronics》2007,18(1-3):19-37
Replacing Pb–Sn with Pb-free solders is one of the most important issues in the electronic industry. Melting, dissolution,
solidification and interfacial reactions are encountered in the soldering processes. Phase diagrams contain equilibrium phase
information and are important for the understanding and prediction of phase transformation and reactive phase formation at
the solder joints. This study reviews the available phase diagrams of the promising Pb-free solders, and their related materials
systems. The solders are Sn–Ag, Sn–Cu, Sn–Ag–Cu, Sn–Zn, Sn–Bi, Sn–In and Sn–Sb. The materials systems are the solders with
the Ag, Au, Cu, Ni substrates, such as Sn–Ag–Au, Sn–Ag–Ni, Sn–Cu–Au, and Sn–Cu–Ni ternary systems. For the Pb-free solders
and their related ternary and quaternary systems, preliminary phase equilibria information is available; however, complete
and reliable phase diagrams over the entire compositional and temperature ranges of soldering interests are lacking. 相似文献
5.
Sn–8Zn–3Bi solder paste was applied as a medium to joint Sn–3.2Ag–0.5Cu solder balls and Cu/Ni/Au metallized ball grid array
substrates at 210 °C. Sn–Ag–Cu joints without Sn–Zn–Bi addition were also conducted for comparison. The shear behavior of
the specimens was investigated after multiple reflow and thermal aging. For each strength test, more than 40 solder balls
were sheared. The shear strength of Sn–Ag–Cu specimens kept constant ranging from 15.5 ± 1.3 N (single reflow) to 16.2 ± 1.0 N
(ten reflows) and the fractures occurred in the solder. Shear strength of Sn–Ag–Cu/Sn–Zn–Bi specimens fell from 15.9 ± 1.7 N
(single reflow) to 13.4 ± 1.6 N (ten reflows). After single reflow, Sn–Ag–Cu/Sn–Zn–Bi specimens fractured in the solder along
Ag–Au–Cu–Zn intermetallic compounds and at Ni metallization. After ten reflows, fractures occurred in the solder and at solder/Ni–Sn–Cu–Zn
intermetallic compound interface. The shear strengths of the Sn–Ag–Cu and Sn–Ag–Cu/Sn–Zn–Bi packages changed little after
aging at 150 °C. Sn–Ag–Cu/Sn–Zn–Bi joints kept higher strength than Sn–Ag–Cu joints. Sn–Ag–Cu joints fractured in the solder
after aging. But the fractures of Sn–Ag–Cu/Sn–Zn–Bi specimens shifted to the solder with aging time. 相似文献
6.
Issues related to the implementation of Pb-free electronic solders in consumer electronics 总被引:2,自引:0,他引:2
D. R. Frear 《Journal of Materials Science: Materials in Electronics》2007,18(1-3):319-330
Consumer electronic applications are the primary target of the Pb-free initiative and package assembly and performance is
affected by the move from eutectic Sn–Pb to Pb-free solder alloys. This paper outlines the key issues and mitigation possibilities
for package assembly using Pb-free solders: High temperature reflow, Interfacial reactions, and Reliability. At the high temperatures
required to reflow Pb-free alloys, moisture absorbed into the package can result in delamination and failure. The reaction
of the Pb-free solder with Ni and Cu metallizations results in interfacial intermetallics that are not significantly thicker
than with Sn–Pb but provide a path for fracture under mechanical loading due to the increased strength of the Pb-free alloys.
The reliability issues discussed include thermomechanical fatigue, mechanical shock, electromigration and whiskering. The
Pb-free alloys tend to improve thermomechanical fatigue and electromigration performance but are detrimental to mechanical
shock and whiskering. Design trade-offs must be made to successfully implement Pb-free alloys into consumer applications. 相似文献
7.
The electronics industry is moving to replace Pb-based solder with Pb-free solder because of the growing environmental regulations
governing the use of lead. Solder joints made from Pb-free solder paste do not yet have an evaluation method to classify its
mechanical properties such as shear strength. In this study, we reflowed solder joints from Sn–3.0Ag–0.5Cu solder paste. To
standardize the shear test method, we measured the shear strength of the solder joint of a 2012 ceramic chip at a shear rate
of 3–60 mm/min and a shear height of 10–380 μm using different shaped shear jigs. We statistically analyzed the optimum number
of shear tests by calculating the accumulative average value, standard deviation, and width of the confidence interval. The
fracture surface was examined by scanning electron microscope and discussed in terms of the shear conditions. 相似文献
8.
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
9.
Jun Shen Shiqiang Lai Yongchang Liu Houxiu Gao Jun Wei 《Journal of Materials Science: Materials in Electronics》2008,19(3):275-280
The effects of third alloying elements (Cu, In, Zn) on the formation of bulk Ag3Sn intermetallic compounds (IMCs) in slowly cooled Sn–3.5Ag lead-free solder were investigated by microstructural observation
and thermal analysis technique. Microstructural observation shows that bulk Ag3Sn IMCs existed in the microstructure of slowly cooled Sn–3.5Ag, Sn–3.5Ag–0.75Cu and Sn–3.5Ag–1.5In alloys, while no bulk
Ag3Sn IMCs formed in the slowly cooled Sn–3.5Ag–2.0Zn alloys. Thermal analysis results indicate that Ag preferably reacted with
Zn to form Ag–Zn IMCs at high temperature rather than reacted with Sn to form Ag3Sn plate. 相似文献
10.
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
11.
Guang Zeng Songbai Xue Liang Zhang Lili Gao 《Journal of Materials Science: Materials in Electronics》2011,22(6):565-578
Nowadays, a major concern of Sn–Cu based solder alloy today is focused on continuously improving the comprehensive properties
of the solder joints formed between the solders and substrates. The key issues and improvements about Sn–Cu–X (X = Ni, rare
earths, Zn, Co, Ga, In, Bi, secondary particles etc.) solder are outlined and evaluated in this paper which compared to Sn–Cu
solder. It can be summarized that by adding appropriate amounts of certain alloying elements X to Sn–Cu solder, and it is
possible to tailor the properties of the solder, such as the melting and solidification behaviors, wettability, microstructure,
interfacial reactions and mechanical properties of the solder. The reliability issues related to the implementation of Sn–Cu–X
solder in advanced electronics system are also introduced, which indicates that further development on the Sn–Cu–X solders
are to be underway. 相似文献
12.
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
13.
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
14.
Jeong-Won Yoon Bo-In Noh Jung-Hyun Choi Seung-Boo Jung 《Journal of Materials Science: Materials in Electronics》2011,22(7):745-750
We investigated the effect of adding cerium (Ce) to low Ag content Sn–1.0wt.%Ag solder on the interfacial reactions between
the Sn–1.0Ag solder and Cu substrate. The formation and growth of interfacial intermetallic compounds (IMCs) between the Sn–1.0Ag–0.3Ce
solder and Cu substrate were studied and the results were compared to those obtained for the Ce-free Sn–1.0Ag/Cu and most
promising Sn–3.0Ag–0.5Cu/Cu systems. The addition of Ce to the Sn–Ag solder significantly reduced the growth of the interfacial
Cu–Sn IMCs, retarded the interfacial reactions between the solder and the substrate, and prevented the IMC from spalling from
the interface. The Sn–1.0Ag–0.3Ce solder alloy had a good interfacial stability with the Cu substrate during solid-state isothermal
aging in the viewpoint of IMC growth. 相似文献
15.
Guang Zeng Songbai Xue Liang Zhang Lili Gao Wei Dai Jiadong Luo 《Journal of Materials Science: Materials in Electronics》2010,21(5):421-440
The objective of this review is to study the interfacial intermatallic compounds (IMCs) between Sn–Ag–Cu based solders and
common substrates, which play a crucial role in solder joints typically present in Pb-free electronics manufacturing. The
microstructural evolution of IMCs at the solder/substrate interfaces is analyzed, while the models and theories describing
the formation/growth mechanism of interfacial IMCs are also introduced. We focus on the influence of a variety of factors
that have been reported recently, including substrates, minor alloying, mechanical stress, electromigration and thermomigration
etc., as full understanding of the mechanisms that determine the formation and growth of interfacial IMCs is important to
reach for developing high reliability solder joints. In the end of this review, the characteristics of the IMCs are compared
and illustrated, which have marked effect on the mechanical properties and fracture behavior as well as reliability of solder
joints. 相似文献
16.
Evolution of interfacial phase formation in Sn–3.0Ag–0.5Cu/Cu (wt%), Sn–3.0Ag–0.5Cu–0.1Ni/Cu, Sn–3.0Ag–0.5Cu/Cu–15Zn, and
Sn–3.0Ag–0.5Cu–0.1Ni/Cu–15Zn solder joints are investigated. Doping Ni in the solder joint can suppress the growth of Cu3Sn and alter the morphology of the interfacial intermetallic compounds (IMCs), however it shows rapid growth of (Cu,Ni)6Sn5 at the Sn–3.0Ag–0.5Cu–0.1Ni/Cu interface. In comparison with the Cu substrates, the Cu–Zn substrates effectively suppress
the formation of Cu–Sn IMCs. Among these four solder joints, the Sn–3.0Ag–0.5Cu–0.1Ni/Cu–15Zn solder joint exhibits the thinnest
IMC, and only (Cu,Ni)6(Sn,Zn)5 formed at the interface after aging. It is revealed that the presence of Ni acts to enhance the effect of Zn on the suppression
of Cu–Sn IMCs in the SAC305–0.1Ni/Cu–15Zn solder joint. The limited formation of IMCs is related to the elemental redistribution
at the joint interfaces during aging. The Sn–3.0Ag–0.5Cu–0.1Ni/Cu–15Zn joint can act as a stabilized interconnection due to
the effective suppression of interfacial reaction. 相似文献
17.
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
18.
For Pb-free soldering materials, two main substitutes are currently being considered, consisting of Sn–Ag and Sn–Ag–Cu eutectics,
both with melting points higher than that of the Sn–Pb eutectic. Therefore, both will require higher soldering temperatures
for industrial applications. Also, both eutectics have a higher surface tension than the Sn–Pb eutectic, requiring wettability
studies on adding Bi, Sb, and In to the eutectics to decrease the melting points and surface tension. The experimental results
for the surface tension were compared with thermodynamic modeling by Butler’s method and were used to create the SURDAT database,
which also includes densities for pure metals, binary, ternary, quaternary, and quinary alloys. To model the surface tension,
excess Gibbs energies of the molten components were taken from the ADAMIS database. For the case of the Ag–Sn system, enthalpies
of formation of Ag3Sn from solution calorimetry were used for checking optimized thermodynamic parameters. In the study of Sn–Ag–Cu–Bi–Sb liquid
alloys, the range of possible Bi compositions for practical applications has been used to formulate a generalized metric of
wettability, which was checked by measurements of the influence of In on the Sn–Ag–Cu system. 相似文献
19.
Dong-Liang Wang Yuan Yuan Le Luo 《Journal of Materials Science: Materials in Electronics》2012,23(1):61-67
Intermetallic compounds formed during the liquid–solid interfacial reaction of Sn–Ag and Sn–Ag–In solder bumps on Cu under
bump metallization at temperatures ranging from 240 to 300 °C were investigated. Two types of intermetallic compounds layer,
η Cu6Sn5 type and ε Cu3Sn type, were formed between solder and Cu. It was found that indium addition was effective in suppressing the formation of
large Ag3Sn plate in Sn–Ag solder. During interfacial reaction, Cu consumption rate was mainly influenced by superheat of solder, contact
area between solder and Cu and morphology of intermetallic compounds. The growth of η intermetallic compounds was governed
by a kinetic relation: ΔX = tn, where the exponent n values for Sn–Ag/Cu and Sn–Ag–In/Cu samples at 240 °C were 0.35 ± 0.01 and 0.34 ± 0.02, respectively.
The n values increased with reaction temperature, and it was higher for Sn–Ag/Cu than that for Sn–Ag–In/Cu sample at the same
temperature. After Cu was exhausted, ε intermetallic compound was converted to η intermetallic compound. The mechanisms for
such growth of interfacial intermetallic compounds during the liquid–solid reaction were investigated. 相似文献
20.
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