Properties Of Solder Alloys Research Articles

Investigation of the mechanical properties of lead-free Sn-58Bi solder alloy with cobalt addition through flux doping

PurposeThis study aims to investigate the effect of incorporating cobalt (Co) into Sn-58Bi alloy on its phase composition, tensile properties, hardness and thermal aging performances. The fracture morphologies of tensile-tested solders are also investigated to correlate the microstructural changes with tensile properties of the solder alloys. Then, the thermal aging performances of the solder alloys are investigated in terms of their intermetallic compound (IMC) layer morphology and thickness.Design/methodology/approachThe Sn-58Bi and Sn-58Bi-xCo, where x = 1.0, 1.5 and 2.0 Wt.%, were prepared using the flux doping technique. X-ray diffraction (XRD) is used to study the phase composition of the solder alloys, whereas scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) are used to investigate the microstructure, fractography and compositions of the solders. Tensile properties such as ultimate tensile strength (UTS), Young’s modulus and elongation are tested using the tensile test, whereas the microhardness value is gained from the micro-Vickers hardness test. The morphology and thickness of the IMC layer at the solder’s joints are investigated by varying the thermally aging duration up to 56 days at 80°C.FindingsXRD analysis shows the presence of Co3Sn2 phase and confirms that Co was successfully incorporated via the flux doping technique. The microstructure of all Sn-58Bi-xCo solders did not differ significantly from Sn-58Bi solders. Sn-58Bi-2.0Co solder exhibited optimum properties among all compositions, with the highest UTS (87.89 ± 2.55 MPa) at 0.01 s−1 strain rate and the lowest IMC layer thickness at the interface after being thermally aged for 56 days (3.84 ± 0.67 µm).Originality/valueThe originality and value of this research lie in its novel exploration of the flux doping technique to introduce minor alloying of Co into Sn-58Bi solder alloys, providing new insights into enhancing the properties and performance of these solders. This new Sn-Bi-Co alloy has the potential to replace lead-containing solder alloy in low-temperature soldering.

Thermal, microstructural, wettability and mechanical properties of Sn1.0Ag0.5Cu composite solder modified with Ti nanoparticles

In this study, highly active Ti nanoparticles (Ti NPs) were added to a low silver Sn-1.0Ag-0.5Cu (SAC105) solder. The thermal, microstructural, interfacial, wettability and mechanical properties of SAC105-xTi NPs (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5 wt%) solders were investigated. The results showed that adding Ti NPs had little effect on the melting point and melting point range of SAC105 solder alloy. The solder alloy containing 0.2 wt% Ti NPs had the lowest coefficient of thermal expansion (CTE) of 21.1 × 10−6 m/°C. The SAC105–0.4 Ti NPs solder has a contact angle of 24.3°, 7.57° lower than the SAC105 solder. However, Ti NPs deteriorate the surface of the solder joint as they oxidize to produce TiO2 during the soldering process, resulting in a higher number of small solder balls precipitating from the surface of the joint. In addition, EPMA showed that Ti NPs adsorbed on the Cu6Sn5 grains, leading to changes in the morphology of the Cu6Sn5 grains and a decrease in the thickness of the IMC layer. The addition of Ti NPs had little effect on the mechanical properties of solder alloys. Excessive Ti NPs will agglomerate, leading to a sharp decrease in the shear strength of the solder joints.

Influence of Fe and Ho additions on Sn-3.0Ag-0.5Cu solder alloy: Microstructure, electrochemical and mechanical properties

In this work, the microstructure, electrochemical and mechanical properties of Sn-3.0Ag-0.5Cu solder alloy with Fe and Ho additions were studied. The results demonstrated that adding of Fe and Ho improved the microstructure of solder alloy and formed FeSn2 phase and Ho5Sn3 phase. Besides, the addition of Fe weakened the microhardness and tensile properties of the solder alloy, which was ascribed to a weak interface between FeSn2 and β-Sn matrix. The microhardness and tensile properties of solder alloy were enhanced by adding Ho owing to the improvement of microstructure and the strengthening of the second phase. Electrochemical tests and atomic force microscopy (AFM) results showed that comparing to the base solder alloy, higher corrosion current densities and rougher surfaces after corrosion were found in the solder alloys with the Fe and Ho additions.

Micromechanical response of SAC305 solder alloy under gamma radiation via nanoindentation approach

PurposeThis paper aims to investigate the effect of different doses of gamma radiation on the micromechanical response (hardness properties and creep behaviour) of 96.5Sn-3.0Ag-0.5Cu (SAC305) solder alloys.Design/methodology/approachSAC305 solder pastes deposited on printed circuit boards (PCBs) were subjected to a reflow soldering process to form soldered samples. The soldered samples were irradiated with a gamma source at different doses (5–50 Gy). Nanoindentation testing was used to determine the hardness properties and creep behaviour after gamma irradiation.FindingsThe results showed that the hardness of SAC305 solder alloys gradually increased up to 15 Gy and then gradually decreased to 50 Gy of gamma irradiation. The highest hardness value (0.37 GPa) was observed on SAC305 solder alloys exposed to 15 Gy irradiation. Hardening of SAC305 solder alloy was suggested to be due to the high defect density induced by the gamma irradiation. Meanwhile, exposure to 50 Gy irradiation resulted in the lowest hardness value, 0.13 GPa. The softening behaviour of SAC305 solder alloy was probably due to the evolution of defect size in the solder joint. In addition, the creep behaviour of the SAC305 solder alloys changed significantly with different gamma irradiation doses. The creep rates were higher at a dose of 10 Gy up to a dose of 50 Gy. Gamma irradiation caused the SAC305 solder alloy to become more ductile compared to the non-irradiated alloy. The stress exponent also showed different deformation mechanisms with varying gamma doses.Originality/valueResearch into the micromechanical properties of solder alloys subjected to gamma irradiation has rarely been reported, especially for Sn-Ag-Cu lead-free solder. Thus, this research provides a fundamental understanding of the micromechanical response (hardness and creep behaviour) of solder, especially lead-free solder alloy, to gamma irradiation.

Effect of Melting at Different Temperatures on the Structure and Mechanical Properties of Solder Alloy (Sn -Ag -In).

Abstract 
 The aim of the present work is to prepare some samples of the alloy solders (Sn-2Ag-18In) at different temperatures(923,873,823,773 and 723k) to investigate some of their structure and different Mechanical properties as function of load and temperature ,The X-ray diffraction analysis of the samples ensures the formation of single phase hexagonal ,The average particle size estimated is( 23.016 – 35.664 )nm. Values of stress exponents (n) were found to be in the range of 0.575 to 3.822 for all alloys. Values of activation energy (Q) of alloys were found to be in the range of 0.287 to 1.899 ev .The average activation energy for the sample at different temperature's prepared , creep resistance and electrical conductivity of samples is calculated at room temperature (289k), its values found to be in the range of(900.6 -10113.7)(W.cm)-1 .
 Keywords: Sn-Ag-In alloy solders ; Nano crystal ; Mechanical properties.
 
 ملخص
 تأثير درجة حرارة الصهر على الخواص التركيبية ومقاومة الزحف والموصلية الكهربائية لسبيكة (القصدير -2 فضه-18انديوم ) . قيست الخواص التركيبية ومقاومة الزحف والموصلية الكهربائية لسبائك (القصدير – 2 فضة -18 انديوم ) باستخدام جهاز حيود الاشعة السينية وجهاز اختبار الزحف الميكانيكي ودائرة التيار المستمر , على التوالي . تم تحضير العينة بنقاوة عالية (99.99%) باستخدام تقنية الصهر في انابيب بيركس عند درجات حرارة مختلفة (923,873,823,773الى 723كلفن). وقد اظهرت تحاليل جهاز حيود الاشعة السينية للسبيكة الثلاثية ( قصدير -2 فضة -18 انديوم )انها تتكون من طور احادي (طور سداسي ) . متوسط الحجم الحبيبي لهذه العينات يتراوح بين ( 23.016 – 35.664 ) نانومتر بينما كثافة الانخلاعات تتزايد مع زيادة إضافة الفضة . وخصائص الزحف درست عند درجات حرارة مختلفة298 , 323, 353 كلفن) تحت تأثير ثلاثة احمال (6.2 , 8.7 , 12.5 ميجا باسكال). تم الحصول على قيم أس الاجهاد في نطاق ا 0.575)الى3.822 ) لجميع السبائك . تم الحصول على متوسط قيم طاقة التنشيط للسبائك في حدود 0.287 الى 1.899 الكترون فولت . وزحف المقاومة و الموصلية الكهربائية قيست عند درجة حرارة الغرفة( 298 كلفن ) قيمها تتراوح بين 900.6)الى10113.7)(اوم-سنتيمتر)-1 .

Multiple linear regression approach to predict tensile properties of Sn-Ag-Cu (SAC) alloys

In this study, a number of microstructural characteristics of SAC207 and SAC307 alloys were quantitatively extracted and utilized in a multiple linear regression (MLR) model. The MLR results well represent the ultimate tensile strength (σu) of both alloys, but not the elongation (δ) of the SAC207 alloy. The addition of the tertiary dendritic spacing considerably improved the MLR results for the SAC307 alloy. These findings, which are more consistent than those obtained by single linear regressions (SLR), might give technical supports in either regulating or improving tensile properties of solder alloys.

Effect of Cu Content on Performance of Sn-Zn-Cu Lead-Free Solder Alloys Designed by Cluster-Plus-Glue-Atom Model.

The mechanical properties of solder alloys are a performance that cannot be ignored in the field of electronic packaging. In the present study, novel Sn-Zn solder alloys were designed by the cluster-plus-glue-atom (CPGA) model. The effect of copper (Cu) addition on the microstructure, tensile properties, wettability, interfacial characterization and melting behavior of the Sn-Zn-Cu solder alloys were investigated. The Sn29Zn4.6Cu0.4 solder alloy exhibited a fine microstructure, but the excessive substitution of the Cu atoms in the CPGA model resulted in extremely coarse intermetallic compound (IMC). The tensile tests revealed that with the increase in Cu content, the tensile strength of the solder alloy first increased and then slightly decreased, while its elongation increased slightly first and then decreased slightly. The tensile strength of the Sn29Zn4.6Cu0.4 solder alloy reached 95.3 MPa, which was 57% higher than the plain Sn-Zn solder alloy, which is attributed to the fine microstructure and second phase strengthening. The spreadability property analysis indicated that the wettability of the Sn-Zn-Cu solder alloys firstly increased and then decreased with the increase in Cu content. The spreading area of the Sn29Zn0.6Cu0.4 solder alloy was increased by 27.8% compared to that of the plain Sn-Zn solder due to Cu consuming excessive free state Zn. With the increase in Cu content, the thickness of the IMC layer decreased owing to Cu diminishing the diffusion force of Zn element to the interface.

Wettability and thermal properties of Sn-0.7Cu- 0.05Ni-xZn solder alloy

This study investigate the effect of Zn additions on wettability and thermal properties of Sn-0.7Cu-0.05Ni lead-free solder alloy. The additional of alloying element have been developed by using casting technique with different percentage of Zn which is 0.5, 1.0 and 1.5 wt.%. The Sn-0.7Cu-0.05Ni-xZn solder alloy samples were then analyzed by using the optical microscope (OM) to observerse the wettability perfomance by contact angle. From this study, it was found that different composition of Zn affected the wettability and thermal properties of Sn- 0.7Cu-0.05Ni solder alloys. The addition of 0.5 wt.% has slightly increase the melting point while the addition of higher than 1.0 wt.% Zn can decrease the melting temperature. The addition of 0.5 wt.% of Zn also can reduce the undercooling of solder alloy. Thus, the minor addition of Zn for Sn-0.7Cu-0.05Ni can influence the wettability and thermal properties of solder alloy.

Fabrication of Novel Geopolymer Reinforced Tin Copper Solder in Suppressing Intermetallic Layer Growth

Currently, lead-free composite solder technology system is the new approach that have been considered as a promising replacement for toxic SnPb solder alloy. Sn-0.7Cu was used as matrix solder alloy while fly ash geopolymer and kaolin geopolymer with different compositions (0.5 wt.%, 1.0 wt.%, and 1.5 wt.%) was added as a reinforcement to increase the properties of solder alloy. The solder composite was prepared by using powder metallurgy method which consist of mixing, compaction, and sintering process via microwave oven. Microwave sintering approach results in more uniform heating, lower pore coarsening with cost-effective and energy efficiency. The chemical composition and morphology of geopolymer reinforcement was analysed by using X-ray Flourescene and Scanning Electron Microscope. The influences of the geopolymer particulates in the monolithic matrix solder on the interfacial intermetallic compound thickness and wettability were investigated by using optical microscope, while the specific value was measured by using J-image software. The melting point temperature were investigated by using differential scanning calorimeter (DSC). The influences of adding types of geopolymer particulates into Sn-0.7Cu lead free solder were investigated in terms of interfacial intermetallic compounds (IMCs) and thermal properties. It is noted that several addition of fly ash geopolymer and kaolin geopolymer particles can remarkably supressed the thickness of intermetallic layer between composite solder and the substrate and thus gives higher melting temperature but somehow certain composition resulted low in mechanical properties. Overall, the addition of 0.5 wt.% of kaolin geopolymer reinforcements into Sn-0.7Cu lead-free improved all the listed properties of the solder materials.

Study of mechanical properties of Ag nanoparticle-modified graphene/Sn-Ag-Cu solders by nanoindentation

In this study, mechanical mixing and ball milling were used to mix a variety of different mass fractions of Ag nanoparticle-modified graphene nanosheets (Ag-GNSs) and Sn-Ag-Cu solder alloys to form composite solder alloys. We found that the latter was superior to the former, as the ball-milled samples showed better mechanical properties through nanoindentation tests. The mechanical properties of solder alloys reinforced with Ag-GNSs were compared with those reinforced with unmodified GNSs, and we found that Ag-GNSs were more beneficial for reinforcement. When the amount of Ag-GNSs increased, the composite solders showed improved Young's modulus, hardness, and creep resistance with the exception of 0.2 wt%. The indentation morphologies were observed by scanning electron microscope (SEM), while the microstructure of the composite solder alloys were analyzed by transmission electron microscope (TEM) and electron back scattering diffraction (EBSD). Due to grain boundary and dislocation strengthening, the mechanical properties of the composite solder alloys have been improved. A modified constitutive creep model considering microstructural strengthening showed great agreement with the experiment data.

Influence of Indium and Antimony Additions on Mechanical Properties and Microstructure of Sn-3.0Ag-0.5Cu Lead Free Solder Alloys

In this research, we investigated the influence of indium and antimony additions on the microstructure, mechanical and thermal properties of Sn-3.0Ag-0.5Cu lead free solder alloys. The results revealed that the addition of 0.5 wt.%InSb into SAC305 solder alloys resulted to a reduced melting temperature by 3.8 °C and IMCs phases formed new Ag3(Sn,In) and SnSb in the Sn-rich matrix with a decreased grain size of 28%. These phases improved the mechanical properties of solder alloys. In addition, the mechanical properties of SAC305 solder alloys increased by adding 0.5 wt.%InSb, resulting in an increase of ultimate tensile strength of 24%, but the percent elongation decreased to 45.8%. Furthermore, the Vickers microhardness slightly increased of the SAC305 solder alloys.

Effect of Cooling Rate on the Microstructural and Mechanical Properties of Sn-0.3Ag-0.7Cu-0.05Ni Solder Alloy

The effect of cooling rate on the microstructural and mechanical properties of Sn-0.3Ag-0.7Cu-0.05Ni lead-free solder alloy was studied. The microstructure of specimens was characterized by using an optical microscope (OM) and an energy dispersive X-ray spectroscopy (EDX). The mechanical properties were performed by using a universal testing machine (UTM). The results showed that the cooling rate of water-cooled specimens was about 2.37 °C/s and the cooling rate of mold-cooled specimens was about 0.05 °C/s. To compare the different cooling rates, it was found that the grain size of water-cooled specimens was finer than that of the mold-cooled specimens, this resulted in an increment of mechanical properties of solder alloy. A higher tensile strength (33.10 MPa) and a higher elongation (34%) were observed when water-cooled and mold-cooled systems were used, respectively. The microstructure of Sn-0.3Ag-0.7Cu-0.05Ni lead-free solder alloy solidified by both cooling systems exhibited three phases: β-Sn, Ag3Sn and (Cu,Ni)6Sn5 IMCs.

A design of a new miniature device for solder joints’ mechanical properties evaluation

This paper makes a focus on the design of a micro-testing machine used for evaluating the mechanical properties of solder alloys. The different parts of the testing device have been developed and assembled in a manner that will facilitate the study of miniature solder joints as used in electronic packaging. A specific procedure for fabricating miniature lap-shear joint specimens is proposed in this work. The tests carried out with the newly developed machine serve to determine the material behavior of solder joints under different controlled loading and temperature conditions. Two new solder alloys, namely SACBiNi and Innolot, are characterized in the study, showing the influence of strain rate and temperature parameters on their respective mechanical responses. In addition, the as-cast and fracture surfaces of the solder joints are observed with a scanning electron microscope to reveal the degradation mechanisms. The SACBiNi solder alloy, which contains less Ni and Sb elements, is found to have smaller shear strength than the Innolot alloy, while its elongation to rupture is significantly improved at the same strain rate level and testing temperature. The highest shear strength is 58.9 MPa and 61.1 MPa under the shear strain rate of 2.0 × 10−2 s−1 and room temperature for the SACBiNi and Innolot solder joints, respectively. In contrast, the lowest shear strength values, 26.6 MPa and 29.5 MPa for SACBiNi and Innolot, respectively, were recorded for the strain rate value of 2.0 × 10−4 s−1 and at temperature of 125℃.

Rapid Growth of Tin Whiskers on the Surface of Sn3.8Ag0.7Cu1.0Y Alloy

It is known that rare-earth elements exhibit high chemical activity and adding trace amount of rare-earth Y in the solder can significantly improve the properties of solder alloy. However, adding excessive rare-earth Y in the solder will result in rapid growth of tin whiskers. The research results show that: if the YSn3 precipitates formed in the interior of Sn3.8Ag0.7Cu1.0Y were exposed to the air, YSn3 precipitates will oxidize and expand in volume, and the tremendous compressive stress produced by the surrounding solder matrix constraining the volume expansion will accelerate the growth of tin whiskers.

Characterization of Eutectic Sn-Cu Solder Alloy Properties Improved by Additions of Ni, Co and In

Abstract Recently, the cost factor of raw materials has emerged continuous improvement of tin-copper solder alloys. This work aims to improve the microstructural and mechanical properties of the eutectic tin-copper solder alloys by addition of nickel, cobalt and indium. The temperature profile of reflow soldering in surface-mount assembly was simulated to produce realistic joint microstructures. Key properties for electronic soldering were characterized, i.e. melting behaviour, solidification beha-viour, wettability, electrical resistivity, microstructures and mechanical properties. The results showed that addition of Ni, Co and In can effectively improve the mechanical properties of Sn-0.7Cu solder alloy i.e. microhardness and shear strength by providing preferred interfacial morphology and formation of intermetallic compound precipitates. The new solder alloys also showed reduced liquidus and solidus temperatures whereas no significant degradation of other key properties were seen.

Disabling of Nanoparticle Effects at Increased Temperature in Nanocomposite Solders

The use of nanoparticles to control grain size and mechanical properties of solder alloys at high homologous temperature is explored. It is found that silica nanoparticles in the 100 nm range coated with 2 nm to 3 nm of gold can be dispersed within solders during the normal reflow soldering process, and that these particles are effective in hardening the solder and restricting dynamic grain growth during compression testing at low homologous temperature. As the homologous temperature increases towards 0.75, the effects of the nanoparticles on both mechanical properties and dynamical grain growth reduce, and by homologous temperatures of 0.86 the effects have completely disappeared. This behavior is explained by introducing the concept of an effective volume fraction of pinning nanoparticles, and the practical implications for using nanoparticles to control solder properties via Zener pinning at high homologous temperatures are discussed.

Influence of Liquid Structure Change on Microstructure and Properties of SnZnBi Solder Alloy

Currently, Pb-free is the primary trend of development for solder alloys, and the existing Pb-free solder alloys are still difficult to replace the traditional tin-lead solder alloys. How to further improve the welding properties of Pb-free solder alloys is the issue we currently faced. In this paper, through melt overheating treatment, the influence of liquid-liquid structure change (LLSC) on the structure and properties of SnZn8Bi3 Pb-free solder alloy has been studied. Experimental results show that the LLSC has obvious effects on the solidification process and solidified microstructure of SnZn8Bi3 alloy: bigger solidification undercooling degree in the solidification process, finer and more dispersed solidification structure, and more importantly, the mechanical and welding properties of the solder alloy have also been obviously improved.

Determination of the Creep Properties of Pb-free Solders for Harsh Environments Using Meso-scale Testing

Solder joints in electronic packages are prone to failure due to the evolution of thermal expansion mismatch strains during thermal cycling. The comparatively wide operating temperature range and long lifetimes of aerospace electronics require high reliability solder joints. Since 2006, high reliability industries (aerospace and military amongst others) that are exempt from lead-free RoHS regulation on account of concerns over the reliability of Pb-free solders have found it increasingly difficult and expensive to continue using traditional Sn-Pb-based solders. Hence there is a pressing need to find a suitable alternative that can match the manufacturing and reliability performance of Sn-Pb. There remains a dearth of data for the constitutive behaviour of Pb-free solders under harsh environment scenarios. Unfortunately, conventional test approaches, particularly in the case of creep behaviour which is critical to solder lifetimes, are expensive and time-consuming. High temperature nanoindentation has been recently developed as a quick method for the determination of creep properties of solder alloys. This paper compares and contrasts nanoindentation creep results for bulk Pb-Sn and lead-free solders. However, there are limits to nanoindentation creep, in particular the load-dependence of the technique. A new meso-scale test approach that lies between nanoindentation and bulk creep testing has been developed. Real ball grid arrays using Pb-free solders have been creep tested in the temperature and stress ranges of operating solder joints. High temperature creep constitutive data has been obtained. The technique offers promising time and materials savings in obtaining important mechanical property data for subsequent use in life-prediction models.

Tensile properties and wettability of SAC0307 and SAC105 low Ag lead-free solder alloys

In this article, the tensile properties of low Ag lead-free solder alloys, SAC0307 and SAC105, are examined under various strain rates and temperatures. The wettability of these solders on Cu pad is also characterized by using different fluxes. The SAC305 and Sn37Pb solder alloys are also studied for comparison. Our results show that the properties of all solder alloys are dependent on the strain rate and temperature. The ultimate tensile strength increases monotonously with the increment of strain rate. Both SAC0307 and SAC105 alloys possess lower strength and higher elongation ratio than SAC305 and Sn37Pb alloys. For all the fluxes used in this study, the SAC0307 and SAC105 alloys show the similar wettability to SAC305, whereas worse than that of Sn37Pb alloy. Increasing the activity of the flux does not improve the wettability of the SAC solder alloys on Cu pad effectively.

Effect of Ag Particles on Wettability and Creep Rupture Life of SnCu Based Composite Solders

Particle-enhanced is the way to improve properties of solder alloys. In the present work, the influence of Ag particle-enhanced on the wettability and creep rupture life of 99.3Sn0.7Cu eutectic solder with Ag content of 1vol% to 10vol% were investigated. It was indicated that the wettability of the composite solders could be improved by adding minute amount of Ag particles. With increasing the amount of Ag particles, the spreading areas of the composite solders increased when Ag was below 5vol%. When Ag was above 5vol%, the spreading areas started decreasing. When Ag content was up to 10vol%, the wettability of the composite solder sharply deteriorated. In addition, the creep rupture lives of the composite solders were longer than that of 99.3Sn0.7Cu eutectic solder at the same condition. When Ag content was 5vol%, the creep rupture life of the composite solder was the longest among the investigated composite solders and about 23 times of that of 99.3Sn0.7Cu eutectic solder.