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Cu nanopaste is a candidate to replace Ag nanopaste, but the oxidation problems associated with Cu nanopaste must be overcome. In this study, we fabricated Cu nanopaste with various contents of sodium dodecylbenzene sulfonate (SDBS), and the oxidation behaviors of Cu nanopaste with various contents of SDBS were investigated. Then, Cu nanopastes were printed using a screen-printing machine and sintered with infrared energy. The fabricated circuits were evaluated using high-temperature storage tests and steady-state temperature humidity bias life testing. The printed Cu pattern with SDBS showed better oxidation-resistant properties than that without SDBS. After the reliability test, 2 wt% of SDBS shows less oxide based on X-ray diffraction, microstructure, and electrical resistivity measurements, and the optimized content of SDBS was 2 wt% in the Cu nanopaste.

Friction stir welding (FSW) is a novel solid-state welding technique. This process has many advantages, such as no consumable requirement, low distortion, low shrinkage, and excellent mechanical properties. Recently, FSW has been successfully used to fabricate metal matrix composites (MMCs), as the process overcomes environmental problems caused by other MMC fabrication processes. In previous studies, the goal was to reinforce the mechanical properties of base materials. In this study, the FSW technique and Ag-decorated carbon nanotubes (Ag-CNTs) were used to enhance the thermal properties of copper, and the microstructures of joints of Ag-CNT-reinforced copper fabricated by FSW were evaluated. The microstructures were analyzed using an optical microscope, and the presence of Ag-CNT in the joint was observed using a scanning electron microscope. Additionally, we confirmed the distribution of Ag-CNTs by electron probe microanalyzer, and the thermal properties of joints were evaluated by laser flash analysis. The Ag-CNT-reinforced Cu composites fabricated by FSW have improved thermal properties compared with conventional copper MMCs.

The mechanical reliability of Sn–MWCNT composite solder containing various content of Sn-decorated MWCNTs (0, 0.05, 0.1, and 0.2 wt%) and Sn–58Bi solder were investigated. The Sn-decorated MWCNTs nanoparticles were used to improve the mechanical reliability of Sn–58Bi solder, which is a representative, low-temperature, lead-free solder. The Sn-decorated MWCNT nanoparticles were synthesized using the polyol method, and the Sn–MWCNT composite solder paste was fabricated by mechanical mixing. The shear and bending tests were conducted to evaluate the mechanical properties of the solder joints. We identified the microstructure of solder to investigate the intermetallic compound and failure mechanism of Sn–MWCNT composite solder. Furthermore, a high-temperature storage test at 100 °C for 1000 h was performed to determine long-term reliability. The shear strength and fracture energy increased about 21% and 23%, respectively, with 0.1 wt% Sn-decorated MWCNTs. In addition, the bending reliability of Sn–58Bi solder increased approximately 25%.

An empirical equation ΔHs, m=0.84n′ gives the enthalpy of solution of 30 branched, linear and cyclic alkanes in glacial acetic acid. The parametern′ is an “effective carbon number” which expresses the number of carbon atoms in the longest chain plus one half of the pendant methyl groups.