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Microstructures, interface reaction, melting characteristics, tensile property, thermal fatigue behavior and wettability of Sn58Bi, Sn35Bi0.3Ag and Sn35Bi1.0Ag solders were investigated. Only Sn phase and Bi phase like net-type distribute uniformly in the Sn58Bi matrix, Sn35Bi0.3Ag and Sn35Bi1.0Ag solder show the AgSn particles in the Sn matrix around net-like Bi phase, at the solder/Cu solder joints, only CuSn intermetallic compound was observed. The liquid phase line temperature of Sn35Bi0.3Ag and Sn35Bi1.0Ag is higher than that of SnBi solder. Sn35Bi1.0Ag solder joints show superiority in mechanical property and fatigue life, which can attribute to the strengthening effect of AgSn particles. Moreover, the wettability of Sn35Bi1.0Ag solder was best of all, and the N atmosphere and RMA flux can enhance the wettability obviously, which can provide the reference support of the research of SnBi base solders. [ABSTRACT FROM AUTHOR]

The relationship between Ce content/CeSn sizes and the whiskers growth is newly reported systematically. The whiskers growth can be observed in the surface of bulk CeSn particles, the rate of whisker growth was significantly slowed with Ce content lower than 0.1 wt%. At higher concentration of Ce, whisker growth rate becomes higher and noticeable. It is thought that the higher Ce chemical potential for oxidation provides a path for the mechanism of whisker growth. With all the other benefits of Ce addition, the potential to promote whisker growth indicate that only dilute concentration of Ce can be tolerated in SnAgCu alloys without whiskering effect. The results demonstrated that the trace amount of Ce can be utilized as additive into SnAgCu solder in microelectronic industry. [ABSTRACT FROM AUTHOR]

In our previous work, a small amount of Al nanoparticles can improve the wettability and mechanical properties of SnAgCu lead-free solders. In this paper, creep properties of SnAgCu solder alloys containing 0.1 wt% Al nanoparticles were studied based on creep testing. It is found that with the addition of Al nanoparticles can enhance the creep resistance of SnAgCu solders. And the Garofalo-Arrhenius creep model was used to describe the creep behavior of SnAgCu and SnAgCu-0.1nano Al solder joints, the parameters were determined based on creep testing. And finite element analysis was utilized to represent the accumulated creep response and calculate the creep fatigue life of solder joints. [ABSTRACT FROM AUTHOR]

In this paper, the wettability of lead-free solders on substrates with fluxes was studied based on reflow process and Taguchi method. Effects of different control factors, including solder materials, fluxes, substrate materials and atmosphere on the wettability of the lead-free solder joints were examined and calculated. Moreover, the effect of rare earth Eu on the wetting of SnAgCu solder was investigated, the effect mechanism was analyzed too. The wettability optimal design in the lead-free solders system has the combination of the SnAgCu-0.04Eu solder, RMA flux, Au/Ni/Cu substrate, and vacuum atmosphere. Moreover, the flux is the most important factor among the control factors in the wettability system. [ABSTRACT FROM AUTHOR]

Growth kinetics of intermetallic compound (IMC) layers formed between SnAgCu solder for reflow soldering and Cu substrate by solid state isothermal aging were investigated at temperatures between 100 and 140 °C. For the aged samples, two distinct layers of IMCs of the type CuSn and CuSn were identified with the later adjacent to the copper substrate. In the as-soldered samples, only a single layer of interfacial CuSn type IMC was formed. Moreover, the apparent activation energies were 96.75 kJ/mol (total IMC), 85.98 kJ/mol (CuSn IMC) and 105.92 kJ/mol (CuSn IMC), respectively. [ABSTRACT FROM AUTHOR]

With more consumer products moving towards environmentally friendly packaging, making solder Pb-free has become an urgent task for electronics assemblies. Solder joints are responsible for both electrical and mechanical connections. Solder joint does not have adequate ductility to ensure the repeated relative displacements due to the mismatch between expansion coefficients of the chip carrier and the circuit board. Materials behavior of solder joints involves a creep-fatigue interaction, making it a poor material for mechanical connections. The reliability of solder joints of electronics components has been found playing a more important role in service for microelectronics components and micro-electro-mechanical systems. So many researchers in the world investigated reliability of solder joints based on finite element simulation and experiments about the electronics devices, such as CR, QFP, QFN, PLCC, BGA, CSP, FCBGA and CCGA, which were reviewed systematically and extensively. Synchronously the investigation on reliability of solder joints was improved further with the high-speed development of lead-free electronic packaging, especially the constitutive equations and the fatigue life prediction equations. In this paper, the application and research status of constitutive equations and fatigue life prediction equations were reviewed, which provide theoretic guide for the reliability of lead-free solder joints. [ABSTRACT FROM AUTHOR]

In this paper, the effect of rare earth (RE) La on the properties of \Sn\9\Zn solder was carried out. The results indicate that RE La plays an important role not only in the wettability and the structure of the solder but also in the mechanical property of the solder joint. The results show that adding trace amount of RE La can remarkably improve the wettability and oxidation resistance of SnZn solder and can enhance the mechanical properties of solder joints. When RE La content is 0.06%, the SnZn-based solder has the best properties. In addition, it is found that \Sn\Zn\0.06\La shows a finer and more uniform microstructure than SnZn, and the sizes of Zn-rich phases are obviously reduced. [ABSTRACT FROM AUTHOR]