Properties Of Solder Research Articles

Corrosion Properties of SAC305 Solder in Different Solution of HCl and NaCl

Potentiodynamic polarization was used to studied the corrosion properties of SAC305 solder in different solution of 1.0 M HCl and 3.5 wt.% NaCl using the same scanning rate of 1.0 mV/s. The polarization curves indicated that corrosion in NaCl was less severe than in HCl solution based on corrosion current and passivation behavior obtained. Morphology and phases obtained after corrosion using SEM and XRD were analyzed. Microstructure analysis shows the present of compact corrosion product with presence of larger flake for polarization in NaCl compared to HCl. Phases present in XRD analysis confirmed the present of SnO and SnO2 corrosion product for sample from both solutions.

Effects of α-Al2O3 nanoparticles-doped on microstructure and properties of Sn–0.3Ag–0.7Cu low-Ag solder

In order to enhance the properties of Sn–0.3Ag–0.7Cu low-Ag solder, α-Al2O3 nanoparticles with various content (0–0.5 wt%) were successfully doped into the solder paste with a self-designed dispersion step. After comprehensive study of the microstructures and properties of the novel nano-composite solder, several satisfactory modified results can be obtained. For instance, the wettability of solder was greatly improved with trace amount of α-Al2O3 nanoparticles-doped. The superior wettability was achieved by Sn–0.3Ag–0.7Cu–0.12Al2O3 solder with spreading area approaching to ~ 79 mm2. Detailed thermodynamic and kinetic analysis of how α-Al2O3 nanoparticles promoting the processes of solder wetting and spreading on Cu substrate were given. In addition, the joint soldered with Sn–0.3Ag–0.7Cu–0.12Al2O3 displayed the highest shear force (57.1 N) with a typical ductile fracture failure mode. This relates to the evidently refined microstructure as well as the well-controlled growth of interfacial Cu6Sn5 IMCs. Corresponding theoretical analysis shows 0.12 wt% Al2O3 nanoparticles-doped can decrease the growth rate constant of interfacial Cu6Sn5 IMCs from 5.08 × 10−10 to 1.71 × 10−10 cm2/s.

Simulation study of thermomechanical fatigue of quilt packaging interchip interconnects

Quilt Packaging QP is a new direct interchip interconnect through metal nodules on chip edges We have performed simulations to study the robustness of QP against fatigue failure For quilts on ceramic carriers thermal stresses are driven primarily by the adhesive between chip and carrier and we have simulated systems with different adhesives as well as different chip material combinations Simulations for the test system estimated cycles to failure over a temperature range of to C The simulation results suggest favorable material properties for solder and adhesive to use for QP or QP like interconnects

Influence of rotating magnetic field on solidification microstructure and tensile properties of Sn-Bi lead-free solders

The solidification microstructures and corresponding mechanical properties of Sn-20Bi and Sn-20Bi-0.4Cu alloys were studied with and without rotating magnetic field (RMF). Without RMF, the microstructures of both solders exhibit great numbers of undesirable columnar structure of dendrite primary β-Sn phase and large Cu6Sn5 phase. The RMF-driven flow has induced columnar-to-equiaxed transition (CET) of dendrite primary β-Sn phase, which simultaneously results in dendrite fragmentation, and provokes distinct grain and intermetallic compound (IMC) refinement effects due to Lorentz force acting on the melt. The individual contributions of RMF on the lattice strain, crystallite size, stress and energy density were evaluated from X-ray peak broadening using various Williamson-Hall models. RMF can also reduce effectively the lattice strain and crystallite size of both solders, which are likely vital prerequisite for property control on metallic materials. Tensile tests showed that the tensile strength of Sn-20Bi solder was enhanced and ductility of Sn-20Bi-0.4Cu alloy was improved. These effects could increase the elastic compliance and develop the drop impact reliability of bulk solders.

Impact of thermal aging on the intermetallic compound particle size and mechanical properties of lead free solder for green electronics

The Sn-Ag3.0-Cu0.5 lead free solder (LFS) alloy is mostly used as good alternative as compared to conventional Tin-Lead (Sn-Pb) due to its good mechanical properties and no harmful effect on environment but it stills has some problems to be solved regarding the growth formation of intermetallic compounds (IMCs). The IMCs present inside the bulk tin (Sn) matrix grow at high temperature and hence their impact on mechanical properties becomes more significant. In this work the effects of lanthanum (La) doping of Sn-Ag3.0-Cu0.5 is investigated as function of IMCs growth and mechanical properties including yield strength (YS) and ultimate tensile strength (UTS) under different thermal aging temperatures. The selected La concentration in this study is 0.4wt%. The aging time is 50h and thermal aging temperatures are 60°C, 100°C and 140°C. The microstructure examination before and after thermal aging is observed using scanning electron microscopy (SEM) followed by image analysis to estimate the nature of IMCs. The chemical composition is confirmed with energy dispersive X-ray (EDX). The YS and UTS are also examined before and after thermal aging for the un-doped and doped samples from stress-strain curves using universal testing machine (UTM). It is investigated that inclusion of 0.4wt% La into Sn-Ag3.0-Cu0.5 solder system results in increasing the IMCs growth rate and hence mechanical properties reduced. It is also observed that the microstructure becomes coarsen after thermal aging due to growth of average IMCs particle size with significant decrease in YS and UTS. Further, mathematical relations with minimum error are developed to predict mechanical properties (YS and UTS) at various levels of aging temperature, showing a reciprocal relationship between aging temperature and mechanical properties.

Assessment of room-temperature short-term stress relaxation and strain relaxation with recovery in Sn-Bi lead-free solders solidified under rotating magnetic field

In this paper, short-term stress relaxation test (SRT) as well as strain relaxation and recovery test (SRRT) were performed to assessment the minimum creep rate of Sn-Bi solder from the primary creep stage at 25 °C. Both techniques allow to determination the effect of rotating magnetic field (RMF) during solidification of Sn-Bi solder on the viscous stress exponents nv and other parameters, and have been established to be appropriate for assessment the initial microstructure dependent flow properties of the alloy solder. Additionally, the viscous strain rate in irreversible viscous flow is developed during primary creep and a power-law relationship was created from experimental data to predict the creep deformation mechanism. It was found that the Sn-Bi solder solidified under RMF had the higher resistance to stress and strain relaxation than that solidified without RMF. The stress exponent values of 9.4–6.3 for dislocation creep were achieved depending on the initial imposed strain, and indicating the role of RMF on refining β-Sn dendrites that affect the density of mobile dislocations. Significant decrease in undercooling (from 13.4 to 5.6 °C) was attained after applying RMF, which has good prospects for industrial application.

Effect of fluxes on Sn-Zn-Bi solder alloys on copper substrate

PurposeThis paper aims to investigate the effect different fluxes have on the mechanical properties of lead-free solders, specifically Sn-Zn-Bi solder alloy. The solder billets were soldered in between copper substrates and flux was applied. The mechanical tests carried out on the solder alloys were tensile and shear tests. They were experimented on with different fluxes, namely, water-soluble (paste), rosin mildly activated (RMA) and insoluble (RMA) flux. From these experiments, the ultimate tensile strength, shear strength, elongation, yield stress, Young’s modulus and the stress-strain curve are derived. The results showed that solder billets that were soldered onto copper substrates with water-soluble flux yielded the highest ultimate tensile strength and shear strength values of 9.9961 MPa and 118.836 MPa, respectively. Billets soldered using RMA flux had the highest values of elongation and Young’s modulus, 0.306 mm and 50,257.295 MPa, respectively. However, on viewing the failure of all the specimens under an optical microscope and scanning electron microscope (SEM), specimens soldered using water-soluble flux possessed the least deformities, depicting their higher level of mechanical properties, entailing their strength and ductility, deeming them as the most suitable flux for microelectronic applications.Design/methodology/approachThe solder billets were soldered in between copper substrates and flux was applied. The mechanical tests carried out on the solder alloys were tensile and shear tests. They were experimented on with different fluxes, namely, water-soluble (paste), RMA and insoluble flux (RMA) flux. From these experiments, the ultimate tensile strength, shear strength, elongation, yield stress, Young’s modulus and the stress-strain curve are derived.FindingsThe results showed that solder billets that were soldered onto copper substrates with water-soluble flux yielded the highest ultimate tensile strength and shear strength values of 9.9961 MPa and 118.836 MPa, respectively.Originality/valueThis paper demonstrated that water-soluble fluxes gave the better strength and were most suitable for microelectronics applications.

Using nanoindentation to investigate the temperature cycling of Sn[sbnd]37Pb solders

Using nanoindentation and energy dispersive X-ray spectrometry (EDS), we have conducted an investigation into corner failures to elucidate not only the nanomechanical properties of Sn37Pb solder balls but also the effects of temperature cycling tests (TCTs). We found that the hardness of Sn37Pb solder balls was greater in central locations [1.18±0.05GPa for room-temperature (RT) sample; 1.3±0.05GPa for TCT sample], but had standard values in corner locations (>0.2±0.02GPa). The modulus increased after the TCTs. Nevertheless, the mechanical properties were closely related to the average area of the α-Pb phase. The average area of the Pb-rich region was more stable after the TCTs than that of the RT sample, due to the enhanced mechanical properties of the Sn37Pb solder, suggesting good reliability. From an analysis of average areas in the RT sample, it appears that the Pb-rich solid solution that formed led to weak SnPb bonds near the corner locations. Electron back-scattered diffraction measurements revealed that grains with grain boundaries formed as a result of accelerated TCT cycling. We conclude that SnPb recrystallization was initiated and propagated after the TCTs, followed by propagation to the interfacial region.

Correlation of Physics-of-Failure to Stress-strain Curve for Quickturn Monitoring of Solder Joint Reliability

Physics-of-failure based reliability prediction technology is one of the key technologies in the field of prognostic and health management (PHM). In this study, physics of failure in solder interconnection is correlated with stress-strain curve obtained by die pull test to predict the joint quality and monitor the property change of solder bump within a reduced time period. Ball-gridarray (BGA) Si chip containing 6,000 solder bumps is used to demonstrate the validity of proposed method. With the conventional method using SEM analysis, it is very time-consuming to observe every single micro-bump and define each failure mode especially when IC includes a great number of solder bumps. The results indicate that it is possible to establish quick-turn monitoring methodology for the solder interconnection reliability and property change from the stress-strain curve of solder joints. Baseline strain-rate for ductile to brittle transition for reference joint of Sn-0.7Cu solder composition is investigated so that all the other deviations from the reference can be captured by using stress-strain relationship. In addition, it is found that failure mode in solder joint is correlated with stress-strain plot and therefore, joint reliability can be predicted without identifying the failure mode of the joints through SEM inspection. This study can provide the guideline for solder joint PHM from solder bump to chip system level.

Surface metallization of Cu/Ni/Au coatings on diamond/Cu composite materials for heat sink application

Abstract Electroless-plating and electro-plating have been used to deposit Cu-Ni-Au coating on diamond/Cu composites. Before electroless copper plating, pretreatment should be applied to the surface of composites by means of boiled HNO 3 etching, sensitization with SnCl 2 and activation with PdCl 2 . The influence of pre-treatment on the electroless copper plating and electroplating Ni/Au is studied in this paper. Scanning electronic microscope, energy dispersive spectroscopy and optical microscope are used to examine microstructure and morphologies of coatings. Results indicated that the uniform and tight bonded Cu/Ni/Au coating have been successfully deposited on the diamond/Cu composites. Meanwhile, high temperature baking, solder wetting and the polarization curve tests are used to evaluate the adhesion strength, solderability and corrosion resistance of Cu/Ni/Au coatings in detail. Investigated results indicated that diamond/Cu covered with Cu-Ni-Au coatings exhibited excellent solderability and mechanical properties.

Effects of AlN Nanoparticles on the Microstructure, Solderability, and Mechanical Properties of Sn-Ag-Cu Solder

The addition of nanosized AlN particles to Sn-3.0 wt pctAg-0.5 wt pctCu (SAC305) lead-free solder alloy has been investigated. The various weight fractions of AlN (0, 0.03, 0.12, 0.21, 0.60 wt pct) have been dispersed in SAC305 solder matrix by a mechanical mixing and melting route. The influences of AlN nanosized particles on the microstructure, mechanical properties, and solderability (e.g., spreadability and wettability) have been carried out. The structural and morphological features of the nanocomposite solder were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscope (TEM). The experimental results show that the best combination of solderability and mechanical properties is obtained at 0.21 wt pct AlN in the solder matrix. The reinforced composite solder with 0.21 wt pct AlN nanoparticles shows ≈25 pct improvement in ultimate tensile strength (UTS), and ≈4 pct increase in the spreadability. In addition, the results of microstructural analyses of composite solders indicate that the nanocomposite solder, especially reinforced with 0.21 wt pct of AlN nanoparticles, exhibits better microstructure and improved elongation percentage, compared with the monolithic SAC305 solder.

Effect of in Addition on Microstructure and Properties of Zn-5Al Solder

The effect of In addition on melting behaviors, microstructure and properties of Zn-5Al solder were investigated. It was found that addition of In decreasing the melting point of Zn-5Al solder. XRD analysis confirmed the presence of Indium in form of α-Zn+β-In solid solution. The segregation of In on grain boundary was observed. Segregation of In on grain boundary caused a significant decrease of strength of the Zn-5Al-In solder compared to Zn-5Al.

Effects of CuZnAl Particles on Properties and Microstructure of Sn-58Bi Solder.

With the purpose of improving the properties of the Sn-58Bi lead-free solder, micro-CuZnAl particles ranging from 0 to 0.4 wt % were added into the low temperature eutectic Sn-58Bi lead-free solder. After the experimental testing of micro-CuZnAl particles on the properties and microstructure of the Sn-58Bi solders, it was found that the wettability of the Sn-58Bi solders was obviously improved with addition of CuZnAl particles. When the addition of CuZnAl particles was 0.2 wt %, the wettability of the Sn-58Bi solder performed best. At the same time, excessive addition of CuZnAl particles led to poor wettability. However, the results showed that CuZnAl particles changed the melting point of the Sn-58Bi solder slightly. The microstructure of the Sn-58Bi solder was refined by adding CuZnAl particles. When the content of CuZnAl addition was between 0.1 and 0.2 wt %, the refinement was great. In addition, the interfacial IMC layer between new composite solder and Cu substrate was thinner than that between the Sn-58Bi solder and Cu substrate.

Nonlinear and Temperature-Dependent Material Properties of AU/SN Alloy for Power Module

AbstractIn recent years, the material Au-20Sn eutectic solder, which is resistant to high temperatures, is used for electric interconnections in high-power modules, the material properties such as temperature and strain rate dependent stress-strain curve are critically needed for reliability assessment of Au-20Sn solder joint. Thus, this study was performed to determine the material properties of Au-20Sn eutectic solder under various strain rates and temperature loads. Many researches using shear test to determine the shear resistance of solder joint, however, the mechanical strength as measured by the shear test is the maximum shear strength of the package joint, but this measurement does not represent the stress-strain behavior of Au-20Sn material. To identify the material properties of Au-20Sn eutectic solder, the tensile test was performed to measure its mechanical strength and nonlinear material properties. The strain rate effect was examined in terms of the influence of the mechanical strength on the Au-20Sn eutectic solder at different tensile rates. The temperature-dependent material properties of Au-20Sn solder were also measured under various thermal loadings, and material properties of Au-20Sn obtained in this research can be applied to the simulation model, the thermomechanical behavior and reliability of the power module can be further analyzed and evaluated.

Effects of graphene nanosheets addition on microstructure and mechanical properties of SnBi solder alloys during solid-state aging

In this work, graphene nanosheets (GNSs) functionalized SnBi solder alloys were synthesized and the effects of GNSs addition on the microstructure evolution and mechanical properties of SnBi alloys during solid-state aging were investigated. The results show that the microstructure and mechanical properties of solders enhanced by 0.03wt% GNSs addition possess the best performance during solid-state aging. After 360h aging at 100°C, the coarse microstructure and growing grains in pure SnBi are effectively inhibited in the GNSs reinforced solders, meanwhile the ultimate tensile strength and elastic modulus of pure samples are improved by 15% and 24% in SnBi-0.03GNSs samples. The failure features after aging show that GNSs can restrain the formation and propagation of micro-cracks at the fracture surface of SnBi alloys. The hardness of solders is also enhanced by GNSs and varies with tensile strength following a linear relationship. Moreover, the strengthening mechanism of GNSs in the composite solders during aging treatment is also analyzed.

Effect of Pr addition on properties and Sn whisker growth of Sn–0.3Ag–0.7Cu low-Ag solder for electronic packaging

In this study, trace amount of rare earth Pr was added into Sn–0.3Ag–0.7Cu low-Ag solder to enhance properties of solders. Experimental results indicated that optimal amount of Pr addition (~0.06 wt%) can improve properties of wettability, shear force and ductility of Sn–0.3Ag–0.7Cu low-Ag solder. This is because that solder with optimal Pr addition not only had a refined microstructure but also owned a regular and thin interfacial IMC layer after soldering on Cu substrate. Meanwhile, we have explained the change of morphology and thickness of interfacial IMC layer after Pr addition based on Kim and Tu’s kinetic model of interfacial IMC growth. However, it was found excessive Pr addition led to the formation of PrSn3 phase, which was easy to be oxidized and became a great deterioration on the properties referred above. Besides, the fracture mode of solder joint also gradually changed from ductile fracture to cleavage fracture. Moreover, this oxidized PrSn3 became the birthplace of Sn whisker since it provided abundant supply of Sn sources and compressive stress for Sn whisker growth. By the in-situ observation of Sn whisker growth in 0.5 wt% Pr-doped solder joint, we obtained that the incubation period of Sn whisker is very short and its growth rate may have a great decrease with time extending. Besides, it was found after 1 day at room temperature, spindly and rod-like Sn whiskers also grew in 0.5 wt% Pr-doped solder joint besides dot-shaped Sn whisker that grew in 0.5 wt% Pr-doped solder matrix. We suggest this may be related with the extra compressive stress provided by interfacial IMC layer growth in 0.5 wt% Pr-doped solder joint.

Corrosion Properties of Sn-9Zn Solder in Acidic Solution

The corrosion properties of Sn-9Zn lead-free solder was studied through potentiodynamic polarization in different concentration of hydrochloric acid (0.5, 1.0, 1.5, 2.0 M). Two types of polarization profile were observed for Sn-9Zn solder at lower concentration acid (0.5 to 1.0 M) and one at higher concentration acids (1.5 to 2.0 M). The morphological analysis showed that two distinctive structures of lamellar-like groove and irregular shaped of the corrosion product compounds formed on the solder surface after being polarized at different concentrations. Phase and elemental analyses revealed the formation of mixed corrosion product such as SnO, SnO2, ZnO, ZnO2, and Zn(OH)2 on the surface after polarization.

The Relationship between XRD Peak Intensity and Mechanical Properties of Irradiated Lead-Free Solder

The variation on mechanical properties and crystalline structure of gamma-irradiated Sn-rich lead-free solder (SAC) were intensively investigated using nanoindentation and X-ray diffraction (XRD) techniques. Samples of solder on a printed circuit board (PCB) with copper substrate were irradiated at low dose (5 Gray) of gamma from Co-60 source. The nanoindentation hardness for β-Sn phase of the solder was found to increase from 0.1935 GPa to 0.2210 GPa after the irradiation. Furthermore XRD peak intensity was also observed to increase as well indicating the occurrence of defect in β-Sn crystal structure due to gamma radiation. The defect contributes to the increment of the hardness by indicating the change in crystallite size of the grains. Microstructure analysis by FESEM-EDAX has also confirmed the indentation was performed with no cracks in subsurface on β-Sn area.

The role of physico-chemical properties of liquid solder in reactive wetting: the Cu/SnZnIn system

The measurements of surface tension, density and viscosity of liquid Sn-Zn eutectic alloys containing 0, 5, 10, 15 and 25 mole fraction of In were carried out using the sessile drop method, dilatometric technique and capillary method. The measurements were performed at temperature range between 493 and 843 K. The technique of sessile drop was applied in the measurements of wetting angles and spreading test in the SnZnIn/ Cu system. Surface tension, density and viscosity measurements were carried out in a protective argon-hydrogen atmosphere. Wettability tests were performed in air in the presence of flux Alu33, at 250?C for 2 minutes. Subsequently, the microstructure of solder and the resulting joints was studied. The addition of In to eutectic Sn-Zn alloy improved the wetting properties and causes a reduction of thickness of the intermetallic compounds layer created at the interface between the liquid solder and the Cu substrate.

Effect of nano Al2O3 additions on the interfacial behavior and mechanical properties of eutectic Sn-9Zn solder on low temperature wetting and soldering of 6061 aluminum alloys

In this study, an addition of Al2O3 nano-particles with a content in the range of 0–1 wt% to Sn-9Zn eutectic solder, were examined in order to understand the effects of Al2O3 additions as the particulate reinforcement to the melting point, wettability, microstructure, interface morphology and hardness as well as mechanical properties of soldering 6061 aluminum alloys. Here, an approach to prepare a composite solder by adding Al2O3 nano-particles to the molten Sn–9Zn solder alloy was developed. In the soldered joint using Sn–9Zn solders, there is a solution layer of Al8ZnSn4 located at the interface. Due to the addition of Al2O3 nano-particles, the scallop-shaped solid solution layer was changed into a flat layer, and its thickness was reduced. In the microstructure of the composite solder containing 1 wt% Al2O3 nano-particles, the fine acicular-shaped Sn-Zn eutectic structure and Al2O3 nano-particles were found to be distributed in the β-Sn matrix. These changes in the interfaces and the microstructure, leading to the improvement of wettability, mechanical properties and hardness of the composite solder.