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Wide bandgap materials have become very attractive for power electronics due to their physical properties that allow junction temperatures up to a theoretical limit of 600°C. In contrast, the maximum operation temperature of conventional silicon semiconductors is limited to approximately 200°C. The high-temperature operation of wide bandgap switches allows an increasing power density of power converters...
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...
Bi element addition effects on Sn-0.3Ag-0.7Cu low-Ag solder properties are studied in this work. Solder alloy with different Bi adding amount, Sn-0.3Ag-0.7Cu-XBi (X = 0, 1.0, 3.0, 4.5), were fabricated. The melting point, wettability, and strength tests were carried out to find the effects of Bi addition on current low-Ag solder. Thermal aging of the solder interconnects with different Bi addition...
In this study, we would analyzed the solid state reaction between Sn2.5Ag solder bump and Cu/Ni under-bump-metallization (UBM). After 150°C thermal aging, we observed that the intermetallic compounds (IMCs) at chip side and interposer side both were Ni3Sn4 IMCs. It indicated that the solder did not react with Cu and the Cu layer was completed. As thermal aging time increased, the thickness of Ni3Sn...
In this work, IMC (Inter metallic compound) of lead free (Sn-Ag-Cu (SAC)) and lead (62Sn-36Pb-2Ag (SP)) solder joint on the four kinds of surface finished of ball grid array (BGA) pad, such as Immersion Tin (ImSn), Organic solderability preservatives (OSPs), Ni-P/Pd/Au (ENEPIG), and Ni-P/Au (ENIG) were investigated by Focus Ion Beam microscope (FIB). Sample after failure ageing conditions (Baking...
The Ni/95Pb5Sn/Cu ternary diffusion couples were used to investigate the cross-interaction between Ni and Cu across a layer of 95Pb5Sn solder. High-lead solder layers with thickness of 100 or 400 μm was electroplated over Cu foils. A pure Ni layer (20 μm) was then deposited over the as-deposited high-lead solder surface. The diffusion couples were then aged at 150 to 250°C for different periods of...
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 line-type Cu/Sn/Ni interconnects were used to determine the effect of electromigration (EM) on the Cu-Ni cross-interaction under the current density of 1.0×104 A/cm2 at 150 °C for 100 h and 200 h. For the purpose of comparison, the line-type Cu/Sn/Ni interconnects were also aged at 150 °C for 100 h and 200 h. After soldering, Ni3Sn4 and Cu6Sn5 IMCs formed at the Sn/Ni and Sn/Cu interfaces, respectively...
The microstructual stability of Sn-8Zn-3Bi/Cu and Sn-8Zn-3Bi-0.3Cr/Cu joints has been investigated under 85 °C temperature and 85% humidity conditions as a function of exposure time. The evolution of interface and near surface cross-sectional microstructures during exposure has been examined. A continuous single layer of intermetallic compound (IMC, hereafter) appears in both of the two kinds of solders...
The current study revealed that the growth kinetics and the interfacial reaction of the Cu/Sn/Ag couples with different thickness solder. For the Cu/Sn/Ag couples, plate-type Ag3Sn was firstly formed at the Sn/Cu interface rather than at the Sn/Ag interface for the Cu/Sn/Ag couple at the initial state of the reflow procedure when the solder thicknesses is 150 μm or 300 μm. Besides, the microstructure...
The η-η' transformation of interfacial Cu6Sn5 in solder joints was studied. Two cooling rates were selected to obtain different grain sizes of intermetallic compounds (IMCs). In the case of air cooling, the compounds were tiny and no η-η transformation was detected in the as-soldered state. Under furnace cooling, however, thick and coarse interfacial IMCs were obtained and η was still stable. After...
Sn-Ag-Cu (SAC) solders are susceptible to appreciable microstructural coarsening due to the combined effect of thermal and mechanical stimuli during service and storage. This results in evolution of joint properties over time, and thereby influences the long-term reliability of microelectronic packages. Accurate prediction of this aging behavior is therefore critical for joint reliability predictions...
Sn-Ag-Cu (SAC) and Sn-Ag alloys are considered to be the most promising Pb-free solders for electronics applications. The properties of these solders can be improved by the addition of minor alloying elements to control the intermetallic compounds (IMCs) that are formed during soldering and high temperature storage/cycling. Additional alloying elements into the solder alloys change the solidification...
In the present study, the interaction between thin film Cu and non-eutectic Sn-In is studied. The effects of the bonding and aging temperature on microstructure, IMC formation and also shear strength are investigated by SEM/EDX, XRD and shear testing. The bonding mechanism is proposed based on the obtained results. The bonding mechanism is proposed to occur over 2 stages: (1) An increase in bonding...
The formation and growth of intermetallic compound layer thickness is one of the important issues in search for reliable electronic and electrical connections. Intermetallic compounds (IMCs) are an essential part of solder joints. At low levels, they have a strengthening effect on the joint; but at higher levels, they tend to make solder joints more brittle. If the solder joint is subjected to long-standing...
In this work, the SAC solder joints with minor Mn or RE (rare earth) additions were bonded on the substrate of OSP Cu surface finishes for evaluating the influence of minor alloying on BIT (ball impact test) behavior. The Mn-doped samples had a better resistance to the degradation in BIT performance suffering long time aging at 150??C. The greater impact force and toughness compared to the other samples...
It is of importance for the reliability of lead-free and lead-bearing solder joints to have better understanding and control of the solder/metallization interactions during soldering. In the reactions between solders and Cu substrate, the formation of micro voids within the Cu3Sn layer had been report by many research groups. Because the Cu3Sn growth had been linked to the formation of micro voids,...
This paper deals with presentation of some new aspects of solder ternary alloy 96.5Sn3Ag0.5Cu (wt.%) - SAC305, in order to determine variations in mechanical properties and microstructure caused by treatment in vapour phase soldering (VPS) as well as by accelerated isothermal aging. These specimens have been melted and solidified on HASL (hot air solder levelling) and Ni/Au (ENIG) PCB (printed circuit...
The morphological features and growth kinetics of interfacial IMCs have shown significant effect on the mechanical properties, and hence, on the reliability of lead free solder joints. The growth behavior of the interfacial IMCs of SnAgCu/Cu solder joint, in reflow and thermal cycling, was investigated with the focus on the influence of reflow dwell time and the cyclic parameters on the growth kinetics...
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