Creep behavior of near-peritectic Sn–5Sb solders containing small amount of Ag and Cu (original) (raw)
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The Study of Creep Properties of Sn-5wt%Sb Lead-Free Solders with Annealing Temperature
Journal of Materials Science Research and Reviews, 2019
Sn-5wt%Sb is one of the materials considered for replacing Pb-bearing alloys in electronic packaging. The creep tests were conducted to investigate the effect of the heat treatments on the mechanical properties of Sn-5wt%Sb lead-free solders. Samples were heat treated at temperatures of 313, 333 and 353 K to produce a range of different grain sizes. Tow-load creep tests were carried out at each temperature for the wire samples to alloys. The results obtained show that there is a relationship between the heat-treatment temperature and the microstructure and that this, in turn, affects the creep properties of the alloys. From the steady state creep rate the stress exponent is described in terms of the heat treatment temperatures. The stress exponent (n) were determined to clarify the deformation mechanism. Based on the n values, it is suggested that the rate controlling creep-deformation mechanism is dislocation climb. Comparisons are made with all alloys on the creep resistance of solder alternatives. The effect of annealing temperature against the strain rate indicated that in increasing annealing temperature, the strain rate is increasing, might be due to the increasing in the grain size. This study revealed that the solder alloy Sn-5wt%Sb have the potential to give a good combination of higher creep resistance and rupture time.
Creep properties of Sn–Sb based lead-free solder alloys
Journal of Alloys and Compounds, 2009
Full implementation of the new generation of lead-free solders requires detailed knowledge and understanding of their mechanical behavior. This paper reports on structure, thermal and tensile creep properties of Sn-5 wt.%Sb, Sn-5 wt.%Sb-3.5 wt.%Ag, and Sn-5 wt.%Sb-1.5 wt.%Au lead-free solder alloys. The results show that the microstructure of Sn-5Sb alloy is characterized by the presence of cubed intermetallic compound (IMC) of SbSn particles (<5 m) within -Sn matrix. The two ternary alloys exhibit additional constituent phases of IMCs Ag 3 Sn for Sn-5Sb-3.5Ag and AuSn 4 for Sn-5Sb-1.5Au alloys. Attention has been paid to the role of IMCs on creep behavior. The tensile creep tests were performed within the temperature range 25-130 • C at constant applied stresses. Activation energy (Q) and stress exponent (n) were determined to clarify the deformation mechanism. This study revealed that the solder alloy Sn-5Sb-1.5Au have potential to gave a good combination of higher creep resistance and rupture time, lower melting temperature and higher fusion heat compared with the other two alloys.
The effects of Zn addition on the microstructure, thermal behavior and tensile creep properties of Sn–1.0Ag–0.3Cu (SAC103) alloy were systematically investigated. Differential scanning calorimetry (DSC) reveals that the reductions of undercooling and pasty range are more significant for Zn-containing solders, although the solidus temperature remains the same or slightly changed. The creep life time of plain SAC103 alloy was remarkably enhanced two times with the addition of 3 wt% Zn. Moreover, significant improvement in creep resistance of 145% and 360% is realized with the addition of 2 wt% and 3 wt% Zn into SAC(103) solder, respectively. The improvement of creep behavior is due to the microstructural change of Zn-containing solders, since the formation of new (Cu,Ag) 5 Zn 8 intermetallic compound (IMC) phase and fine fiber-like Ag 3 Sn precipitates at the surface of β-Sn matrix could provide more obstacles for dislocation pileup , which enhanced the stress exponent values and improved the creep resistance and creep life time. These results show that the Garofalo model is suitable for describing the steady-state creep behavior of SAC(103) solders over the tested stress and temperature ranges.
For development of lead-free solder for advance electrical components, the correlation of microstructure with thermal and creep properties of novel Ni-doped Sn–0.5Ag–0.7Cu (SAC (0507)) lead free solders has been investigated. Results showed that addition of 0.05Ni into the lead-free SAC (0507) solder led to the microstructural refinement, more uniform distribution of the Ag 3 Sn, (Cu,Ni) 6 Sn 5 intermetallic compounds (IMCs) and small primary b-Sn grains. However, the SAC (0507)–0.1Ni alloy has relatively high fraction of the primary b-Sn phase and the IMCs appeared coarse within the matrix compared with the other examined alloys. DSC results showed that the addition of Ni did not produce any significant effect on the melting behavior. Interestingly, 0.05 wt.% Ni addition exhibited a drastically reduced und-ercooling to be 6.3 °C. In terms of creep behavior, the SAC (0507)–0.05Ni gave the highest creep resistance due to the fine dispersion of IMCs. Furthermore, 0.05 wt.% Ni addition can evidently increase the creep– rupture life, about 2.0 times greater than that of the baseline SAC (0507) and approximately 5.0 times better than that of SAC (0507)–0.1Ni solder. Meanwhile, the SAC (0507)–0.1Ni alloy shows lower creep resistance which is mainly attributable to smaller volume fraction of the precipitate phases. Based on the obtained stress exponents and activation energies, it is proposed that the dominant deformation mechanism in SAC (0507) solders is dislocation climb over the whole temperature range investigated.
Materials Science and Engineering: A, 2003
Understanding and quantification of creep behavior of lead-free solder joints are essential for lifetime prediction of electronic systems. This is especially true for circuits with surface mount and chip components that are subjected to severe environments and higher temperatures. Creep deformation behavior of Sn Á/4Ag Á/0.5Cu, Sn Á/3.5Ag Á/0.5Ni and Sn Á/2Ag Á/1Cu Á/1Ni solder alloys was determined at room temperature (25 8C) and at elevated temperature (85 8C) using miniature single shear lap joint specimens that are comparable in size to actual solder joints used in electronic packaging. Various creep parameters such as global creep strain, secondary creep rates as well as the strain for the onset of tertiary creep in the solder joint were determined. The effects of Cu and Ni alloy additions on the creep properties of eutectic Sn Á/3.5Ag solder joints were studied by comparing with the creep deformation behavior of eutectic Sn Á/3.5Ag solder joints that were used as the baseline. General findings in this study revealed that the creep resistance of Sn Á/4Ag Á/0.5Cu solder joints is comparable to but slightly higher than that of eutectic Sn Á/3.5Ag solder joints at both room and elevated testing temperatures, particularly at lower stresses. The Sn Á/3.5Ag Á/0.5Ni solder joints have comparable creep resistance to Sn Á/4Ag Á/0.5Cu and eutectic Sn Á/3.5Ag solder joints at 85 8C, but much better creep resistance at room temperature. The Sn Á/2Ag Á/1Cu Á/1Ni solder joints were two orders of magnitude less creep resistant than solder joints made with other solder materials at 85 8C. However, the shear strains for the onset of tertiary creep in Sn Á/2Ag Á/1Cu Á/1Ni solder joints were found to be the highest at 85 8C. Microstructural analysis showed significant creep deformation along Sn grain boundaries. #
Impression creep behavior of lead-free Sn–5Sb solder alloy
Materials Science and Engineering: A, 2007
Creep behavior of the lead-free Sn-5Sb solder alloy in the cast and wrought conditions was investigated by impression testing. The tests were carried out under constant stress in the range of 18-135 MPa and at temperatures in the range of 298-403 K. Assuming a power law relationship between the impression rate and the punching stress, stress exponents of 2.8 and activation energies of 41.3 kJ mol −1 were determined for the wrought material over the whole stress and temperature ranges studied. For the cast condition, however, stress exponents of 5.4 and 11.4 and activation energies of 53.8 and 75.8 kJ mol −1 were obtained at low and high stresses, respectively. The n value of 2.8 and the activation energy of 41.3 kJ mol −1 , which is very close to the activation energy for grain boundary diffusion of -Sn, together with a very fine grain size of 4.5 m and a uniform distribution of fine SnSb particles, may suggest that grain boundary sliding is the dominant creep mechanism in the wrought condition. For the cast material with a coarse grain size of 280 m, the low stress regime activation energy of 53.8 kJ mol −1 , which is close to that of the self diffusion of pure Sn, and a stress exponent of 5.4 suggest that the operative creep mechanism is dislocation climb. This behavior is in contrast to the high stress regime in which, the n = 11.4 and Q = 75.8 kJ mol −1 are indicative of a dislocation creep mechanism.
Journal of Alloys and Compounds, 2011
The near peritectic Sn-5Sb Pb-free solder alloy has received considerable attention for high temperature electronic applications, especially on step soldering technology, flip-chip connection. In the present study, a separate addition of the same amount of Ag and Cu are added with the near-peritectic Sn-5Sb solder alloy to investigate the effect of a third element addition on the microstructural, thermal and mechanical properties of the newly developed ternary solder alloys. The results indicate that the melting point of Sn-5Sb solder is enhanced by Ag and Cu additions. Besides, the Ag and Cu content refine the microstructure and form new intermetallic compounds (IMCs) with the near-peritectic Sn-5Sb solder alloy. The tensile tests revealed that all alloys exhibit higher mechanical strength with increasing strain rate and/or decreasing testing temperature, suggesting that the tensile behavior of the three alloys is strain rate and temperature dependence. The yield and ultimate tensile strength are higher for Sn-5Sb-0.7Cu alloy compared with Sn-5Sb and Sn-5Sb-0.7Ag alloys. Good mechanical performance of Sn-5Sb-0.7Cu solder is often correlated to a fine -Sn grain size and more dispersed Cu-Sn IMC particles, which makes the solder exhibit high strength and yield stress.
Materials & Design, 2012
The eutectic Sn-0.7Cu solder alloy is widely used in electronic packaging in which the creep property of the solder joint is essential to meet the global demand for longer operating lifetime in their applications. In this study, the influence of Ag and In additions on tensile creep behavior and thermal properties of bulk eutectic Sn-Cu solder alloy is reported. Results show that addition of Ag and In resulted not only in the formation of new Ag 3 Sn and c-SnIn 4 intermetallic compounds (IMCs), but also in the refinement of grain size of Sn-0.7Cu solder from 0.50to0.50 to 0.50to0.15 lm. Accordingly, the creep properties of the Ag or In-containing solder alloys are notably improved. The creep strain rate increases and creep lifetime decreases as the applied stress level and temperature increase. Room and elevated-temperature creep rate of bulk Sn-Cu solder was reduced by 521.0% after Ag addition, but for In addition the reduction was about 200.7%. These differences are attributed to the presence of new Ag 3 Sn and c-SnIn 4 precipitates and their rules in classical dispersion strengthening as a separate phases. Moreover, the eutectic temperature of Sn-0.7Cu is decreased from 227.4 to 217.8 and 224.0°C with the addition of Ag and In, respectively.
Metallurgical and Materials Transactions A, 2007
Metallurgical, mechanical, and environmental factors all affect service reliability of lead-free solder joints and are under extensive study for preparation of the transition from Sn-Pb eutectic soldering to lead-free soldering in the electronic industry. However, there is a general lack of understanding about the effects of solidification conditions on the microstructures and mechanical behavior of lead-free solder alloys, particularly on the long-term reliability. This study attempts to examine the creep resistance of the SnAg -Cu eutectic alloy (Sn-3.8Ag-0.7Cu, SAC387) with a variety of solidification conditions with cooling rates ranging from 0.3°C/s to 17°C/s. Results indicate that solidification conditions have a major influence on the creep resistance of SAC387 alloy; up to two orders of magnitude change in the steady-state creep rates were observed at low stress levels. An understanding of the mechanical property change with microstructures, which are determined by the solidification conditions, should shed some light on the fundamental deformation and fracture mechanisms of lead-free solder alloys and can provide valuable information for long-term reliability assessment of lead-free solder interconnections.