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Purpose-This paper aims to investigate the characteristics of ultra-fine lead-free solder joints reinforced with TiO 2 nanoparticles in an electronic assembly. Design/methodology/approach-This study focused on the microstructure and quality of solder joints. Various percentages of TiO 2 nanoparticles were mixed with a lead-free Sn-3.5Ag-0.7Cu solder paste. This new form of nano-reinforced lead-free solder paste was used to assemble a miniature package consisting of an ultra-fine capacitor on a printed circuit board by means of a reflow soldering process. The microstructure and the fillet height were investigated using a focused ion beam, a high-resolution transmission electron microscope system equipped with an energy dispersive X-ray spectrometer (EDS), and a field emission scanning electron microscope coupled with an EDS and X-ray diffraction machine. Findings-The experimental results revealed that the intermetallic compound with the lowest thickness was produced by the nano-reinforced solder with a TiO 2 content of 0.05 Wt.%. Increasing the TiO 2 content to 0.15 Wt.% led to an improvement in the fillet height. The characteristics of the solder joint fulfilled the reliability requirements of the IPC standards. Practical implications-This study provides engineers with a profound understanding of the characteristics of ultra-fine nano-reinforced solder joint packages in the microelectronics industry. Originality/value-The findings are expected to provide proper guidelines and references with regard to the manufacture of miniaturized electronic packages. This study also explored the effects of TiO 2 on the microstructure and the fillet height of ultra-fine capacitors.

This paper presents a study on structural assessment of ultra-fine package assembly with nanocomposites lead free solder joint after reflow soldering process. In this work, various nanoparticles (i.e. TiO 2 , Fe 2 O 3 and NiO) with different weight percentage (i.e., 0.01, 0.05 and 0.15 wt.%) were successfully incorporated into SAC305 solder paste using a mechanical solder paste mixer to synthesize novel lead-free composite solders. Effects of the nanoparticles addition on quality of joining and fillet height between various weightage (wt.%) for the ultra-fine package assembly in the reflow soldering process have been investigated by using a scanning electron microscope (SEM) system equipped with an energy dispersive X-ray spectroscopy (EDS) and XTV 160 xray inspection system. Experimental results show the addition of TiO 2 , Fe 2 O 3 and NiO nanoparticles with 0.15wt.%, 0.05wt.% and 0.01wt.%, respectively, produce the best fillet height of each composition of nanoparticles solder paste. Among all these new composition of nanoparticles solder paste, NiO nanoparticles reinforced solder paste with 0.01wt.% yielded the highest fillet height. The miniaturized solder joints do not cause any problem in terms of solder voids. The findings show the capability of the reflow soldering process in assembling miniaturized electronics assembly and expected to provide a reference in electronic package industry.

Purpose This study aims to investigate the NiO nano-reinforced solder joint characteristics of ultra-fine electronic package. Design/methodology/approach Lead-free Sn-Ag-Cu (SAC) solder paste was mixed with various percentages of NiO nanoparticles to prepare the new form of nano-reinforced solder paste. The solder paste was applied to assemble the ultra-fine capacitor using the reflow soldering process. A focussed ion beam, high resolution transmission electron microscopy system equipped with energy dispersive X-ray spectroscopy (EDS) was used in this study. In addition, X-ray inspection system, field emission scanning electron microscopy coupled with EDS, X-ray photoelectron spectroscopy (XPS) and nanoindenter were used to analyse the solder void, microstructure, hardness and fillet height of the solder joint. Findings The experimental results revealed that the highest fillet height was obtained with the content of 0.01 Wt.% of nano-reinforced NiO, which fulfilled the reliability requirements of the international IPC standard. However, the presence of the NiO in the lead-free solder paste only slightly influenced the changes of the intermetallic layer with the increment of weighted percentage. Moreover, the simulation method was applied to observe the distribution of NiO nanoparticles in the solder joint. Originality/value The findings are expected to provide a profound understanding of nano-reinforced solder joint’s characteristics of the ultra-fine package.