We investigated the effect of material combinations of adhesive film (NCF) and build-up substrates on non-metallurgical interconnection reliability in several test element group (TEG) samples. The initial electrical conductivity results in each TEG sample confirmed the validity of the assumed failure mechanism at high temperatures. In this situation, the interconnection reliability deteriorates when the material combination causes a large plastic strain in the gold bump during temperature cycling. The low temperature failure mechanism was also clarified. At low temperatures, a bimetallic warpage due to a thermal mismatch during the cooling process reduces the compressive contact stress in the gold bumps at the corners of the chip. From these failure mechanisms, we found that thinning the silicon chip is an effective means of enhancing interconnection reliability at both high and low temperatures.

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In this paper we report on an investigation into appropriate reflow profiles for BGA joints using Sn-Ag-Bi-In solder, which has a lower melting point than Sn-Ag-Cu solder. We examine the relationship between the interfacial microstructure and mechanical characteristics of the solder joints compared with Sn-Zn-Bi solder. When soldering Sn-3Ag-0.5Cu BGA balls on Cu/Ni/Au pads, Sn-8Zn-3Bi has high joint strength at 503 K or higher and Sn-3.5Ag-0.5Bi-8In has strength at a lower temperature of 493 K. This implies that Sn-Ag-Bi-In type solder is more appropriate for soldering at lower temperatures. A stratified Ni-Sn layer formed on the joint interface when the Sn-3Ag-0.5Cu BGA ball was soldered on a Cu/Ni/Au pad using Sn-3.5Ag-0.5Bi-8In at 483-493 K. At 503k or higher, blocks of (Cu, Ni) ₆Sn₅phases formed unevenly on the joint interface and lower strength resulted. These results suggest the appropriate reflow thermal profile of the Sn-3.5Ag- 0.5Bi-8In solder joints with the Sn-3Ag-0.5Cu BGA ball on the Cu/Ni/Au pads should be in the range of 483-493K. Even if the reflow peak temperature is over 493 K, slowing down the cooling speed by 2 K/s can prevent a decrease in joint strength.

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We have proposed an application of an optical pin having an end of a 45-dgree micro mirror to coupling between optical wirings and optical devices in Optical Surface Mounting Technology. In this paper, experimental studies on optical characteristics of the optical pin having an end coated with a metallic film were reported. Then, the fabrication process of a through-hole on a polymeric waveguide substrate by a laser ablation technique was described. Next an optical pin was actually inserted into the through-hole and the coupling efficiency was studied. Theoretical studies on optical coupling characteristics were also performed using a ray tracing simulation. It was shown that the optical pin has high feasibility by using both metallic coated optical pin and index matching oil.

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Three types of solder ball (Sn-37Pb, Sn-3.5Ag-0.75Cu and Sn-8Zn-3Bi) were jointed on a substrate (Au/Ni-B) which was deposited by electroless Ni-B alloy plating with immersion Au plating processing. The jointing strengths of each solder alloy on Au/Ni-B were measured by the heating-type single-bump pull test. The boundary layer of each solder alloy on Au/Ni-B was analyzed using a SEM and EPMA. It was found that each intermetallic compound of the Ni-Sn, Cu-Ni-Sn and Au-Zn systems was formed along the interfaces between each type of solder and the Au/Ni-B and that these jointed each solder alloy to the Au/Ni-B. Also, enrichment of the B content in the Ni-B alloy film was caused along the jointing phase boundary by the jointing of Sn-37Pb and Sn-3.5Ag-0.75Cu solders.

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In this study, Ni/MWCNT composite electroplating was developed with a dispersed MWCNT Ni plating bath. The MWCNT was dispersed uniformly in the bath by a dispersion material and the Ni/MWCNT composite was electrodeposited from the dispersed MWCNT nickel plating bath. The Ni/MWCNT composite electroplating obtained at the optimum conditions showed flat and smooth surfaces. The Ni/MWCNT composite electroplating obtained in this study showed excellent mechanical and thermal characteristics. This Ni/MWCNT composite plating also demonstrated outstanding wear characteristic as sliding contacts. Especially it had an outstanding thermal characteristic of emissivity, in the broad wavelength range and dissipated the heat generated in the thermal chamber effectively. Maximum emissivity reached 0.89 (wavelength: 3-30μm) . Additionally, it maintained a high fixed value for that wavelength. It had the effect of decreasing heat resistance as a heatsink.

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