Papers by Keyword: Solder

Abstract: The article presents a method for eliminating the crystallization of thermal nodes and shrinkage defects in the form of micro-friable cavities. The method of soldering on castings from steel grades VNL-1 and VNL-6 using 5VA powder solder has been investigated. Also, the optimal soldering modes were determined, the effects of soldering modes on the properties of the base material and the soldered joint were studied, the corrosion resistance was investigated, the corrosion resistance of the soldered joints in corrosive environments. The conducted studies of sealing by soldering cast parts with microdefects lead to the following results: increased corrosion resistance; ensuring increased tightness; improving the presentation; elimination of surface microdefects.

Abstract: The first-principles calculations by CASTEP program based on the density functional theory is applied to calculate the cohesive energy, enthalpy of formation, elastic constant, density of states and Mulliken population of Ag₃Sn、AgZn₃ and Ag₅Zn₈. Furthermore, the elastic properties, bonding characteristics, and intrinsic connections of different phases are investigated. The results show that Ag₃Sn、AgZn₃ and Ag₅Zn₈ have stability structural, plasticity characteristics and different degrees of elastic anisotropy; Ag₃Sn is the most stable structural, has the strongest alloying ability and the best plasticity. AgZn₃ is the most unstable structure, has the worst plasticity; The strength of Ag₅Zn₈ is strongest, AgZn₃ has the weakest strength, the largest shear resistance, and the highest hardness. Ag₅Zn₈ has the maximum Anisotropy index and Ag₃Sn has the minimum Anisotropy index. Ag₃Sn、AgZn₃ and Ag₅Zn₈ are all have covalent bonds and ionic bonds, the ionic bonds decrease in the order Ag₃Sn>Ag₅Zn₈>AgZn₃ and covalent bonds decreases in the order Ag₅Zn₈>Ag₃Sn>AgZn₃.

Abstract: Solder alloys are important joining medium widely used in the electronics industry to connect components to printed circuit board PCB. The Sn-Pb solder alloys have been the cornerstone medium used for a long time. Unfortunately, the use of Pb was banned by the European Union due to the harmful environmental and health issues with Pb. Therefore, in this study, the Sn-50Bi and Sn-50Bi+2%TiO2 nanoparticles lead-free solder alloy is investigated based on their shear strength, Vickers hardness, and melting temperature. The investigation shows that the hypo eutectic Sn-50Bi has a low melting temperature of approximately 145°C, and the 2%TiO₂ nanoparticles reinforced Sn-50Bi has a melting temperature of around 182°C, which is lower than the traditional Sn-Pb (Tm=183 °C) and Sn-Ag-Cu (Tm=227°C). Furthermore, the developed Sn-50Bi had a Vickers hardness and shear strength of 26.81 HV and 40.78 MPa respectively, higher than the other leaded and lead-free solders. However, after the reinforcement, the hardness increased by 12% (30 HV) and a slight increase of 2.5% (42.4MPa) in shear strength. Overall, the addition of the TiO₂ nanoparticles showed a clear influence on the Sn-Bi properties. The results obtained from this study seem satisfactory to the electronic industry and the environment.

Abstract: Utilization of Sn-3.0Ag-0.5Cu to replace toxic lead-based solder was only feasible if the corrosion performance of this solder was assured. To obtain this information, potentiodynamic polarization was implement in 3.5 wt. % NaCl. The morphological and structural changes were investigated via crucial characterization methods (SEM and XRD). Collective evidences verified that the needle-like corrosion product confirmed to be made ofSnO, SnO₂ and SnCl^- and responsible to passivation behavior of this solder.

Abstract: Corrosion properties of Sn-9Zn and Sn-0.7Cu solder were investigated in 3.5 wt.% NaCl. The scanning rates used were fixed at 1.0mVs^-1 to study the effect of diffferent adding element which is Cu and Zn into the corrrosion properties of Sn-based solder. The morphological and structural properties of the samples were compared before and after the corrosion. The morphological analysis observed two types of corrosion product which is compacted and loosely-compacted corrosion product after the samples was polarized in 3.5% NaCl solution.

Abstract: The corrosion of Sn-Zn-Bi lead free solder in 6M KOH electrolyte was conducted. The study was done using 3 different KOH concentrations (3M, 6M and 9M) and the immersion technique was used to produce corrosion. Due to the nature of immersion, the solder material was prepared by punching it into small billets size after melting it homogenously on a commercial hotplate. The immersion was set to 7, 14 and 21 days. After the specific days have fulfilled the sample billets were removed and tested. The corrosion of this solder was measured using various method such as graphical analysis, surface roughness, corrosion penetration rate (CPR) and optical microscope. In this research, it was found out that the sample billets taken from 6M concentration compared to 3M and 9M showed more corrosion this was supported by the outcome of the test. The 6M believed to provide best corrosion on the solder billets because of its high ionic conductivity value.

Abstract: The microstructural properties and intermetallic (IMC) formation of Sn-Ag-Cu (SAC) through varying amounts of zinc were examined in this study while having tin held at constant composition. Samples were prepared and heated in a furnace for 168 hours to achieve complete solidification and homogenization. Results showed relatively fine microstructure primarily containing Sn dendrites, eutectic, and pro-eutectic phases. Microstructures for each alloy was similar for which majority of them formed copper-based IMCs and Sn dendrites. The alloy (0.7Sn-0.15Ag-0.1Cu-0.05Zn) containing minimal amount of zinc with high amount of Ag resulted to high Vickers hardness number. Structural analysis showed that these group of alloys composed mainly of β-Sn, Cu₆Sn₅, and Ag₃Sn.

Abstract: 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.

Abstract: 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.

Abstract: Corrosion properties of Sn-0.7Cu solder were investigated in 1 M HCl. The scanning rates used were 0.5, 1.0, 1.5 and 2.0 mVs^-1 to study the aggressiveness level of HCl electrolyte in various environment. The morphological, elemental and structural of the samples were compared before and after the corrosion. Scan rate 1.0 mVs^-1 was chosen as the most optimum scan rate during corrosion analysis. The morphological analysis observed two types of corrosion product which is compacted and loosely-compacted corrosion product after the samples was polarized in 1 M HCl.