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At present, composite solder pastes are getting a lot of attention, especially composite Sn based solders reinforced by nanoparticles. Indeed, CoSn3 is a strong nucleating agent of Sn crystal, which has potential application value in the field of electronic packaging. However, there is no reliable synthetic path for CoSn3 nanoparticles at present. In this article, a chemical synthesis method for CoSn3 nanoparticles is developed. Here, CoCl2 and SnCl2 are reduced by NaHB4 in triethylene glycol (TEG), dispersed by ultrasonics, and heated to 350 °C in a tube furnace for growth. The CoSn3 nanoparticles with a diameter of about 150 nm are obtained by heating at 350 °C for 10 min. The CoSn3 nanoparticles undergo a step reaction in the process of synthesis and go through different stages of merging and annexation during their growth. The crystal growth behavior and the process of orientation change during the nucleation and growth of CoSn3 nanoparticles are studied, especially the two growth mechanisms, namely OU (orientation unified) and OA (orientation attached). By mixing CoSn3 nanoparticles with SAC305, we obtain a kind of strengthened composite soldering paste. There are obvious six-fold cyclic twins in the joints made by this soldering paste.

This review investigates the measurement methods employed to assess the geometry and electrical properties of through-silicon vias (TSVs) and examines the reliability issues associated with TSVs in 3D integrated circuits (ICs). Presently, measurements of TSVs primarily focus on their geometry, filling defects, and the integrity of the insulating dielectric liner. Non-destructive measurement techniques for TSV contours and copper fillings have emerged as a significant area of research. This review discusses the non-destructive measurement of contours using high-frequency signal analysis methods, which aid in determining the stress distribution and reliability risks of TSVs. Additionally, a non-destructive thermal detection method is presented for identifying copper fillings in TSVs. This method exploits the distinct external characteristics exhibited by intact and defective TSVs under thermoelectric coupling excitation. The reliability risks associated with TSVs in service primarily arise from copper contamination, thermal fields in 3D-ICs, stress fields, noise coupling between TSVs, and the interactions among multiple physical fields. These reliability risks impose stringent requirements on the design of 3D-ICs featuring TSVs. It is necessary to electrically characterize the influence of copper contamination resulting from the TSV filling process on the reliability of 3D-ICs over time. Furthermore, the assessment of stress distribution in TSVs necessitates a combination of micro-Raman spectroscopy and finite element simulations. To mitigate cross-coupling effects between TSVs, the insertion of a shield between them is proposed. For efficient optimization of shield placement at the chip level, the geometric model of TSV cross-coupling requires continuous refinement for finite element calculations. Numerical simulations based on finite element methods, artificial intelligence, and machine learning have been applied in this field. Nonetheless, comprehensive design tools and methods in this domain are still lacking. Moreover, the increasing integration of 3D-ICs poses challenges to the manufacturing process of TSVs.