Sn–Ag–Cu lead-free solders, containing alloy elements and nanoparticles, have been extensively investigated. With the extensive prevalence of 3D IC package, a major concern of Sn–Ag–Cu based solders today is continuously focused on extending service life of solder bonding formed between solders and substrates. The critical issues and improvements on Sn–Ag–Cu solders bearing alloys and nanoparticles are outlined and evaluated in this review. It can be summarized that appropriate content of certain alloys or nanoparticles addition to Sn–Ag–Cu solder is possible to tailor the solder properties, such as the melting and solidification behaviors, oxidation resistance, wettability, (interfacial) microstructure, and mechanical properties. Worthy of note is that reliability issues such as creep behavior, thermomechanical fatigue, electromigration, thermomigration and Sn whisker were briefly discussed and analyzed to lay down a solid foundation for the future development of 3D IC technology.

Recent progress of Sn–Ag–Cu lead-free solders bearing alloy elements and nanoparticles in electronic packaging

Microstructural array and solute content affecting electrochemical behavior of Sn-Ag and Sn-Bi alloys compared with a traditional Sn-Pb alloy

Two-dimensional ternary materials are attracting widespread interest because of the additional degree of freedom available to tailor the material property for a specific application. An In1-xSnxSe phototransistor possessing tunable ultrahigh mobility by Sn-doping engineering is demonstrated in this study. A striking feature of In1-xSnxSe flakes is the reduction in the oxide phase compared to undoped InSe, which is validated by spectroscopic analyses. Moreover, first-principles density functional calculations performed for the In1-xSnxSe crystal system reveal the same effective mass when doped with Sn atoms. Hence, because of an increased lifetime owing to the enhanced crystal quality, the carriers in In1-xSnxSe have higher mobility than in InSe. The internally boosted electrical properties of In1-xSnxSe exhibit ultrahigh mobility of 2560 ± 240 cm2 V-1 s-1 by suppressing the interfacial traps with substrate modification and channel encapsulation. As a phototransistor, the ultrathin In1-xSnxSe flakes are highly sensitive with a detectivity of 1014 Jones. It possesses a large photoresponsivity and photogain (Vg = 40 V) as high as 3 × 105 A W-1 and 0.5 × 106, respectively. The obtained results outperform all previously reported performances of InSe-based devices. Thus, the doping-engineered In1-xSnxSe-layered semiconductor finds a potential application in optoelectronics and meets the demand for faster electronic technology.

Sn-Doping Enhanced Ultrahigh Mobility In1-xSnxSe Phototransistor.

In creating the next generation of crystalline silicon (c-Si) solar cells, the goals are to improve energy conversion efficiency and reduce costs. Here, we demonstrate all-room-temperature-processe...

All-Room-Temperature Processed 17.25%-Crystalline Silicon Solar Cell

Growth evolution of self-catalytic tin-doped indium oxide nanowires

This paper presents the effect of indium (In) content on the melting temperature, wettabililty, dross formation, and oxidation characteristics of the Sn-2Ag-3Bi-xIn alloy. The melting temperature of the Sn-2Ag-3Bi-xIn alloy (2 ≤ x ≤ 6) was lower than 473 K. The melting range between the solidus and liquidus temperatures was approximately 20 K, irrespective of the indium content. As the indium content increased, the wetting time increased slightly and the maximum wetting force remained to be mostly constant. The dross formation decreased to approximately 50% when adding 1In to Sn-2Ag-3Bi, and no dross formation was observed in the case of Sn-2Ag-3Bi-xIn alloy (x ≥ 1.5) at 523 K for 180 min. Upon approaching the inside of the oxidized solder of the Sn-2Ag-3Bi-1.5In alloy from the surface, the O and In contents decreased and the Sn content increased based on depth profiling analysis using Auger electron spectroscopy (AES). The mechanism for restraining dross (Sn oxidation) of Sn-2Ag-3Bi alloy with addition of indium may be due to surface segregation of indium. This is due to the lower formation energy of indium oxide than those of Sn oxidation.

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Ae-jeong Jeon

Papers

Effect of Indium Content on the Melting Point, Dross, and Oxidation Characteristics of Sn-2Ag-3Bi-xIn Solders