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In this paper, carbon nanotube (CNT) and Ni-coating modified CNT (Ni-CNT) were compared as the reinforcing dopants in the Sn57.6Bi0.4Ag solder joints. The comparisons were made in three main aspects, including the dispersion of the dopants, the micromorphology evolution of the solder matrix and the reinforcement of reliability performance of the solder joints. The dispersion was evaluated via observing...
The electromigration (EM) performance of pristine and ZrO2 doped Sn58Bi solder was studied using line-type structure, in order to reduce current crowding at the solder/pad interface. Cu/solder/Cu interconnects were applied with a direct current of 2.5 A, which generated a current density of 7.96×103 A/cm2, and stored in an oven at a temperature of 70 °C. After 300 hours current stressing, samples...
Reinforcement materials such as carbon nanotubes (CNTs), have been demonstrated to be beneficial in improving composite-solder reliability through their super electrical, mechanical and thermal properties. However, interfacial interaction weakness still exists between CNTs and solder alloys. In this study, we managed to incorporate nickel-coated multi-walled carbon nanotubes (Ni-CNTs) into Sn3.0Ag0...
Electromigration problem under current stressing has challenged the reliability of electronic products for a long time, which is more serious as the current applied is increasing. Adding nanoparticles have been proved to be effective in improving the mechanical and electrical properties of solder joints. This work studied the impact of Ag element on electromigration behavior of SnCu0.7 solder joints...
The further miniaturization of electronic devices brings the challenge to the electronic packaging, especially for 3D interconnection as the miscrostructure of the solder joint could be replaced by IMC fully without any solder bulk remain. In this paper, both FE modeling and experimental testing were applied to investigate the stress distribution and the fracture mode of the solder joint under tensile...
Effect of Cu substrates and solder alloy on the formation of kirkendall voids in the solder joints during thermal aging was investigated. Solder joints with three types of Cu bonding pads (electroplated Cu, polycrystalline Cu and single-crystal Cu) and Sn-based solders (Sn-3Ag-0.5Cu and Sn-37Pb) were prepared, and subsequently the samples were aged at 150°C and 175°C, Under the same aging conditions,...
In present paper, the effect of miniaturization on the microstructure and mechanical property of solder joints is investigated. With the miniaturization of solder joints, the thickness of IMC decreases, while, the IMC proportion to the solder joint increases; meanwhile, the concentrations of base materials in the bulk also increase with the reducing stand-off height (SOH). Due to the interaction of...
This study investigates intermetallic compound (IMC) growing behavior at different stand-off heights (SOH) in miniature Cu/Sn-4.8Bi-2Ag/Cu solder joints. The solder joints with SOH of 10, 20, 50 and 100 mum will be studied, and the microstructures and compositions will be discussed. Meanwhile the tensile strength and the fracture mode of Sn-4.8Bi-2Ag solder joints will be also studied. The results...
The relationship among the electrical resistance, the thickness of the IMC layer and the aging timer of the micro SOH solder joints is investigated in present paper. It's found that the composition of compositions of the intermetallic compounds are Cu3Sn near the Cu side and Cu6Sn5 near the solder side; With the increasing of aging time, the thickness of the Cu3Sn increased while the thickness of...
Due to the miniaturization trend and functional demand in high-density microelectronic packaging, the thermomigration in flip chip solder joints owing to the joule heating becomes a serious reliability issue. In this study, a novel apparatus which can provide a sufficient temperature gradient cross the solder joint in the specimen was used to carry on the thermomigration experiment separated from...
BGAs packaging offer high pin counts and lower interconnecting space, and are suitable for high density packaging. However, it is difficult to inspect individual solder joints on BGA assembly by conventional visual methods and need a complicated practice on rework. Ball impact test is a useful method to estimate the reliability of BGA solder joint. In this study, the three-dimensional explicit finite...
In this paper, the effect of the stand-off height (SOH) on the microstructure and tensile strength of Cu/Sn-8Zn-3Bi/Cu and Cu/Sn-9Zn/Cu solder joints with SOH of 100 mum, 50 mum, 20 mum and 10 mum were studied. The results show that as the SOH is reduced, the needle-like Zn-rich phase steadily decrease until completely disappeared in both of the two solder joints. For Cu/Sn-9Zn/Cu, Cu5Zn8 IMC is formed,...
To investigate the effect of the stand-off height (SOH) on the microstructure and mechanical behavior of certain solder joints, Cu/Sn9Zn/Cu solder joints with SOH of 100??m, 50??m 20??m and 10?? were prepared and studied. It was found that as the SOH is reduced, Zn content in solder bulk has a rapid decrease due to consumption by the reflow reaction, hence, the microstructure of solder bulk is changed...
Anti-shock property of lead-free Sn96.5-Ag3.0-Cu0.5 solder bumps was investigated by the high speed impact to explore the relation among the fracture modes and the reflow profile and the microstructure of solder joint. Solder bumps were formed with various reflow profiles and multi-reflow and then subjected to the impact test under a constant speed of 1.8 m/s and a shear standoff of 50 mum. The results...
This study investigates the effect of the stand-off height (SOH) on the microstructure and tensile fracture mode of Cu/Sn9Zn/Cu solder joints. Solder joints with SOH of 100 mum, 50 mum and 20 mum are studied. It is found that as the SOH is reduced, Zn content has a rapid decrease in the solder bulk, while, the intermetallic compound (IMC) layer proportion increases. SOH of the solder joint also has...
The effect of interfacial IMCs (intermetallic compounds) proportion on the reliability of miniature lead-free solder joint was studied. The miniature lead free solder joint was formed with Sn-3.5Ag-0.5Cu or Sn-3.5Ag solder alloys and two copper bars that the ends were plated with Ni and Au. Several sizes of micro-joints were gotten to measure the effect of IMCs proportion. Optical microscope (OM)...
Solder paste print property is critical to product yield in a SMT (surface mount technology) line. Investigation has shown that poor solder paste printability results in a large amount of defects. In this letter, basing on the rolling phenomenon during solder paste printing process, a novel tester was developed to measure the solder paste printability. This device offers a uniform printing condition,...
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