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Plated Ni is a commonly used barrier layer for direct bond copper (DBC) substrates used in high-temperature and high-power applications. The Ni plating method can be electrolytic or electroless, and the composition may be pure Ni, Ni:P, or Ni:B. With a melting point of 356 °C, eutectic Au88Ge12 (wt.%) solder preforms can be used for die attach in high-temperature applications up to 325 °C. The reactivity...
This study was aimed at quantifying critically relevant topics about the influence of intermetallic compounds (IMC) within power electronics reliability such as the influence of soldering profile on the growth rate of IMC in large area solder joints, estimation of IMC thickness during non-isothermal ageing and the impact of IMC thickness on reliability. To this end, test samples were soldered using...
Sn whisker has been found since 1940s.[1] The formation mechanism of whiskers was controversial. There were two possible mechanisms. Some scientists thought whisker formation were the result of recrystallization or abnormal grain growth, however others suggested that the atomic migration of Cu caused by compressive stress gradient were the main driving force of whisker formation. In latest study,...
In recent years, Ag alloy wire has attracted great interest as a novel bonding material to replace the conventional Au wire bonding. Ag wire has the advantages of great workability, high electrical conductivity and low growth rate of intermetallic compound at bonding interface. However, in literatures, studies on mechanisms of the growth of Ag-Al intermetallic compounds and their impact on bonding...
The Zn-Al solder alloy is a promising candidate to replace the conventional high lead solders (Pb-5Sn, Pb-10Sn) in automotive applications, which work in a harsh environment combined with thermal and mechanical loads. In this work, the effects of concurrent vibration and elevated temperature on the Zn-Al solder interconnection on Cu or Ni-P plated Cu substrates were studied. The test samples by forming...
The copper substrates with different preferred orientations (200) and (220) were prepared and the interfacial reactions of the Cu(200)/Sn and Cu(220)/Sn diffusion couples were studied after annealing at 423K. The thickness and morphology of the intermetallic compounds were investigated. The appearance of the Cu3Sn was observed at Cu(220)/Sn interface after aged for 4 hours and then the thickness of...
The copper substrates with different preferred orientations (200) and (220) were prepared and the interfacial reactions of the Cu(200)/Sn and Cu(220)/Sn diffusion couples were studied after annealing at 423K. The thickness and morphology of the intermetallic compounds were investigated. The appearance of the Cu3Sn was observed at Cu(220)/Sn interface after aged for 4 hours and then the thickness of...
In this paper, the formation and growth of intermetallic compounds (IMCs) of Sn-8Zn-3Bi-0.3Cr solder on Cu, Ni and Ni-W substrates have been investigated. For the Cu substrate, only Cu5Zn8 intermetallic compound was observed. For the Ni substrate, a Ni5Zn21 film formed at the interface due to the fast reaction between Ni and Zn. For the Ni-W substrate, a thin Ni5Zn21 film appeared between the solder...
Microstructure evolutions of as-reflowed and aged electroplated Cu/Sn/Cu sandwich structure with 20 or 40μm Sn layer have been investigated. Cu3Sn was observed at lower side of Cu/Sn/Cu structure with 40μm Sn layer after isothermal aging treatment for 24 hours, as for that structure with 20μm Sn layer, Cu3Sn appeared after aging for 48 hours. Regardless of Sn volume, the thickness of the blanket Cu...
The interfacial reactions between (111) Cu single crystals and lead-free solders (pure Sn, Sn-0.7Cu and Sn-0.7Cu-0.1Ni) during solid-state aging at 150 °C were investigated in this study. The morphological evolution and the growth behavior of interfacial IMCs during short-period (0 to 100 h) aging process were studied. For the solders without Ni, the interfacial Cu6Sn5 grains displayed prism shape...
Although lead free soldering has been the main stream of industry since 2006, with the replacement of eutectic SnPb system by SnAgCu system, the development of drop-in lead-free alternatives for high melting high lead solder alloys is still far from mature. BiAg alloy exhibits acceptable bulk strength but very poor ductility and wetting, therefore is not acceptable as an option. In current work, a...
In lead free solder alloys — SnAgCu or SnZn alloys — the knowledge of the composition and the mechanical behavior of their IMCs is important to understand the reliability of small solder joint built up by one or two grains. Metallographic investigations, hardness testing and EBSD measurements (Electron Backscatter Diffraction) will be combined to characterize the mechanical and physical parameters...
Intermetallic compound (IMC) plays great roles in connecting components to PCB boards, as well as die attach materials connecting chips to substrates. Cracks in IMC may leads to failure in an electronic product function. Therefore it is important to investigate the mechanical properties of the IMC to ensure the reliability of the solder joints. In this paper, a nanoindentation test was performed at...
This article deals with the creation and growth of intermetallic compounds (IMCs) in solder joints. The test specimens of copper substrate were made for this experiment. The soldered joints were created on the test specimens by hand soldering process at the temperature of 250°C. Four lead-free solder alloys and one tin-lead solder alloy were chosen for research of IMCs. The test specimens were divided...
Nowadays, nanoelectroctronic, electro-nanotechnologies environmental friendly products become the roadmap in industry. Hence, nanoscale of reinforcement into lead-free solder becomes more popular rather than the micro size of reinforcement. In this paper, Cobalt nanoparticles-reinforced Sn-Ag-Cu composite solders were prepared by thoroughly blending 0.75 wt% of cobalt nanoparticles with near eutectic...
In this study, varying amounts of Ni-CNTs were incorporated into the Sn-Ag-Cu matrix to form the composite solders. The interfacial intermetallic thickness formed on the Ni/Au metallized Cu substrate was determined under the as-soldered and isothermally aged (at 150°C for up to 42 days) conditions. The results of the interfacial intermetallic thickness showed that for the case of the unreinforced...
The experimental samples mainly are the assembled OSP PCB with the Plated-Through-Hole (PTH) components which leads are manufactured with Sn/Ni/Cu substrates and the soldering process is Wave-Soldering (W/S) with two kinds of lead-free SAC solder bars categorized as Sn-3.0wt%Ag-0.5wt%Cu (SAC305) and Sn-0.3wt%Ag-0.7wt%Cu (SC0307). In addition, the test conditions are defined that the experimental temperatures...
A new lead-free solder alloy Sn3Ag0.5Cu3Bi0.05Cr (SACBC) was prepared by adding 3.0 wt.% Bi and 0.05 wt.% Cr on the basis of the composition of Sn3Ag0.5Cu(SAC). The tensile strength and the growth behavior of the interfacial intermetallic compound (IMC) of SAC/Cu substrate and the SACBC/Cu solder joints during isothermal aging at 150°C for 0, 24, 168, 500 and 1000 hours were comparatively investigated,...
The influence of the standoff height, pad size and isothermal aging on the microstructure and shear fracture behavior of Cu/Sn-3.0Ag-0.5Cu/Cu BGA structured interconnects were investigated using the lap-shear test. The experimental results show that the thickness of intermetallic compounds (IMC) layer at the solder/Cu interface increases with decreasing standoff height of the joints. The size of Kirkendall...
The effect of electromigration (EM) on the solid state interfacial reactions in line-type Cu/Sn/ENIG interconnect was investigated under the current density of 5.0×103 A/cm2 at 150 °C for 100 h and 200 h. The Cu/Sn/ENIG specimens were also aged at the same temperature and durations for comparison. After soldering, Cu6Sn5 and Ni3Sn4 IMCs formed at the Cu/Sn and ENIG/Sn interfaces, respectively. During...
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