A review: microstructure and properties of tin-silver-copper lead-free solder series for the applications of electronics

Purpose The research on lead-free solder alloys has increased in past decades due to awareness of the environmental impact of lead contents in soldering alloys. This has led to the introduction and development of different grades of lead-free solder alloys in the global market. Tin-silver-copper is a lead-free alloy which has been acknowledged by different consortia as a good alternative to conventional tin-lead alloy. The purpose of this paper is to provide comprehensive knowledge about the tin-silver-copper series. Design/methodology/approach The approach of this study reviews the microstructure and some other properties of tin-silver-copper series after the addition of indium, titanium, iron, zinc, zirconium, bismuth, nickel, antimony, gallium, aluminium, cerium, lanthanum, yttrium, erbium, praseodymium, neodymium, ytterbium, nanoparticles of nickel, cobalt, silicon carbide, aluminium oxide, zinc oxide, titanium dioxide, cerium oxide, zirconium oxide and titanium diboride, as well as carbon nanotubes, nickel-coated carbon nanotubes, single-walled carbon nanotubes and graphene-nano-sheets. Findings The current paper presents a comprehensive review of the tin-silver-copper solder series with possible solutions for improving their microstructure, melting point, mechanical properties and wettability through the addition of different elements/nanoparticles and other materials. Originality/value This paper summarises the useful findings of the tin-silver-copper series comprehensively. This information will assist in future work for the design and development of novel lead-free solder alloys

Effect of Different S AC Based Nanoparticles Types on the Reflow Soldering Process of Miniaturized Component using Discrete Phase Model Simulation

The wetting formation and nanoparticles dispersion on adding nanoparticles to the lead free solder Sn-3.0Ag-0.5Cu (SAC305) is methodically investigated using Discrete Phase Model (DPM) simulation and applied on a 01005 capacitor component. Different types of nanoparticles, namely titanium dioxide (TiO2), nickle oxide (NiO) and Iron (III) oxide (Fe2O3) with varying weight percentages, 0.01wt%, 0.05wt% and 0.15wt% that is doped in SAC305 are used. The study of two-way interactions between multiphase volume of fluid (VOF) and discrete phase model (DPM) shows excellent capability in tracking the dispersed nanoparticles immersed in the wetted molten solder. In this study, real reflow profile temperature setup will be used to mimic the conventional reflow process. Based on the findings, the fillet height managed to achieve the minimum required height set by IPC standards. As the concentration of the nanoparticles doped in the molten solder increases, higher time is required for the wetting process. In general, the doped NiO nanoparticles at 0.05wt% has the lowest wetting time compared to other cases. The study of the instantaneous nanoparticles trajectory tracking was also conducted on a 3D model and 2D cross sectional view to identify the exact movement of the particles. Additionally, it was also observed that the velocity and pressure distribution increases as the weight percentage of the nanoparticles increases

An investigation into nano-particulates reinforced SAC305-based composite solders under electro- and thermo-migration conditions

With the rapid development in electronic packaging due to product miniaturisation, the size of solder joints is decreasing considerably, thus the failure of solder interconnects induced by electro-migration (EM) and thermo-migration (TM) became a reliability concern. The incorporation of foreign reinforcement can effectively improve properties of the solder alloys. However, this presents an imperative need for a further investigation to elaborate the underlying fundamentals associated with the reliability of reinforced solders. In this study, the Sn-Ag-Cu (SAC) based solder alloy powders as matrix were incorporated with Fullerene (FNS), TiC and Ni-coated graphene (NG) reinforcements to form composite solders through powder metallurgical method. These composite solders were then characterised in terms of their microstructure, physical property, solderability, followed by a systematic investigation of their performance under isothermal ageing, current stressing and large thermal gradient, respectively. The results showed that three types of reinforcements were successfully incorporated into the solder matrix; with all reinforcements added being embedded in the solder matrix or around the intermetallic compounds (IMC). The average loss of FNS and TiC particles in the solders was approximately 80% after the initial reflow, while this was only 40% for NG particles. It has been observed that β-Sn and Ag3Sn in the SAC solder alloys can be refined by adding appropriate amount of FNS and TiC, which is beneficial to the wettability with a reduced coefficient of thermal expansion (CTE) with the minimal influence on the melting point and electrical resistivity of solder alloys. For the SAC alloys without reinforcements, obvious extrusion of interfacial IMC at the anode was present after 360 hours of current (1.5×104 A/cm2) stressing, while the changes of surface profiles of all reinforced solders were unnoticeable. Under the current stressing regimes, a continuous increase of interfacial IMCs at the anode of the original SAC alloys was observed, but decreased at the cathode with stressing time. For the composite solders, both anode and cathode showed a continuous growth of interfacial IMCs; the growth rates of IMCs at the anode were greater than that at cathode. In addition, NG and TiC were found to be most effective to retard the growth of Cu3Sn IMC under current stressing. A gradient in hardness across the stressed SAC joints was present, where it was harder at anode. However, no such obvious gradient was found in SAC/FNS and SAC/NG solder joints. FNS and NG were proven to be beneficial to prolong the service life of solder joints up to approximately 7.6% and 10.4% improvements, respectively. Thermal stressing made the interfacial IMC in the original SAC joints to grow at the cold end considerably; causing serious damage at the hot end after 600 hours under temperature gradient of 1240K/cm stressing; a large number of IMCs, cracks and voids appeared in the SAC solder joints. However, a uniform increase of IMCs at both sides in the composite solders was observed without apparent damages at the interfaces under the same thermal stressing conditions, indicating an effective reduction of the elemental migration in the reinforced solders. Although there were also some voids and IMCs formed in the composite solder joints after a long-term thermal stressing, the integrity of the composite solder joints was enhanced compared with the SAC alloys. During thermal stressing, the dissolution rate of Cu atom into the SAC solder joints was estimated to be 3.1×10-6 g/h, while the values for SAC/FNS, SAC/NG and SAC/TiC were only 1.22×10-6 g/h, 1.09×10-6 g/h and 1.67×10-6 g/h, respectively

Thermo-migration behavior of SAC305 lead-free solder reinforced with fullerene nanoparticles

In this work, SAC305 lead-free solder reinforced with 0.1 wt. % fullerene nanoparticles was prepared using a powder metallurgy method. A lab-made setup and a corresponding Cu/solder/Cu sample for thermo-migration (TM) test were designed and implemented. The feasibility of this setup for TM stressing was further verified with experimental and simulation methods; a temperature gradient in a solder seam was calculated as 1070 K/cm. Microstructural evolution and mechanical properties of both plain and composite solder alloys were then studied under the condition of TM stressing. It was shown that compared to unreinforced SAC305 solder, the process of diffusion of Cu atoms in the composite solder seam was remarkably suppressed. After the TM test for 600 h, Cu/solder interfaces in the composite solder seam were more stable and the inner structure remained more intact. Moreover, the addition of fullerene reinforcement can considerably affect a distribution of Cu6Sn5 formed as a result of dissolution of Cu atoms during the TM test. Hardness data across the solder seam were also found notably different because of the elemental redistribution caused by TM

A review: microstructure and properties of tin-silver-copper lead-free solder series for the applications of electronics

Purpose: The research on lead-free solder alloys has increased in past decades due to awareness of the environmental impact of lead contents in soldering alloys. This has led to the introduction and development of different grades of lead-free solder alloys in the global market. Tin-silver-copper is a lead-free alloy which has been acknowledged by different consortia as a good alternative to conventional tin-lead alloy. The purpose of this paper is to provide comprehensive knowledge about the tin-silver-copper series. Design/methodology/approach: The approach of this study reviews the microstructure and some other properties of tin-silver-copper series after the addition of indium, titanium, iron, zinc, zirconium, bismuth, nickel, antimony, gallium, aluminium, cerium, lanthanum, yttrium, erbium, praseodymium, neodymium, ytterbium, nanoparticles of nickel, cobalt, silicon carbide, aluminium oxide, zinc oxide, titanium dioxide, cerium oxide, zirconium oxide and titanium diboride, as well as carbon nanotubes, nickel-coated carbon nanotubes, single-walled carbon nanotubes and graphene-nano-sheets. Findings: The current paper presents a comprehensive review of the tin-silver-copper solder series with possible solutions for improving their microstructure, melting point, mechanical properties and wettability through the addition of different elements/nanoparticles and other materials. Originality/value: This paper summarises the useful findings of the tin-silver-copper series comprehensively. This information will assist in future work for the design and development of novel lead-free solder alloys. © 2019, Emerald Publishing Limited

Obtaining and Characterization of New Materials

At present, more and more procedures and technologies used to discover and characterize new materials are available, including advanced characterization techniques.This Special Issue covers a wide range of topics about obtaining and characterizing new materials, from the nano to macro scales, including for new alloys, ceramics, composites, biomaterials, and polymers and the procedures and technologies used to enhance their structure, properties, and functions. To select new materials for future use, we must first understand their structure and their characteristics using modern techniques such as microscopy (SEM, TEM, AFM, STM, etc.), spectroscopy (EDX, XRD, XRF, FTIR, XPS, etc.), and mechanical tests (tensile, hardness, elastic modulus, toughness, etc.) and their behaviors (in vitro and in vivo; corrosion; and thermal—DSC, STA, DMA, magnetic properties, and biocompatibility), among many others

Technology of Welding and Joining

In this book, you will find information on new materials and new welding technologies. Problems related to the welding of difficult-to-weld materials are considered and solved. The latest welding technologies and processes are presented. This book provides an opportunity to learn about the latest trends and developments in the welding industry. Enjoy reading

Corrosion Resistance

The book has covered the state-of-the-art technologies, development, and research progress of corrosion studies in a wide range of research and application fields. The authors have contributed their chapters on corrosion characterization and corrosion resistance. The applications of corrosion resistance materials will also bring great values to reader's work at different fields. In addition to traditional corrosion study, the book also contains chapters dealing with energy, fuel cell, daily life materials, corrosion study in green materials, and in semiconductor industry