Electrodeposited tin-zinc eutectic alloy is a promising candidate to replace tin-lead solder coatings and provide low temperature soldering. The eutectic alloy film (Sn-9.0Zn, mass%) of the desired constituent was deposited at cathode current density 0.5-3A/dm² in a sulfosuccinate bath using the additive polyoxyethylene-α-naphthol (POEN) . The presence of POEN increased tin deposition polarization, markedly inhibited preferential deposition of tin over a noble potential range, and an appreciable amount of zinc was codeposition. The bath is stable systems, precipitate consisting of metastannic acid were not observed after standing for six months. The eutectic alloy film consists of β-tin and zinc phases, and its solidus temperature was 198°C. Whisker were not observed on the eutectic alloy film on the copper substrate after one year of aging at room temperature.

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Through-hole plating and via-filling are studied by using the through-holes and via-holes coexisted circuit boards. The effect of additives on the reaction of copper deposition is also studied by using the electrochemical techniques. Conformal plating for through-holes and via-filling are accomplished by electrodeposition with high current density at the initial stage, or intermittently cut off of the current during electroplating. It is considered that selective adsorption of additives on the corner part of through-holes and via-holes are an important factor for conformal plating and via-filling. Effect of additives on copper deposition is greatly influenced by the applied high current density, or cut off interval of the current during electroplating. In addition, suppression effect of copper deposition derived from adsorption of PEG during the cut off of the current is depended on the molecular weight of PEG and the presence of chloride ions.

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This paper describes the suppression of spurious responses by a planar bandpass filter (BPF) using λ/2 resonators consisting of a microstrip line (MSL) . Firstly, the variation of resonance characteristics is examined by the choise of the excitation structure to the λ/2 resonator. The improvement of out-of-band characteristics is discussed systematically by examining not only the improvement of skirt characteristics but also (1) the suppression of spurious responses and (2) compatibility between the improvement of skirt characteristics and suppression of spurious responses. From the calculated and experimental results, it is confirmed that the further improvement of the out-of-band characteristics can be possible by the positive use of the basic characteristics of the λ/2 resonator itself. Moreover, we have confirmed the flexibility of our proposal for the various transmission lines.

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Ball mount technique has not been conventionally applied to flip-chipped ICs, because of its limitation of mechanical handling. However, a method of micro ball mount shown in this paper is so unique that it is possible to operate 130μm diameter balls and to put them at 200μm intervals. Using Cu-cored solder balls whose center portion is made of a Cu ball, it works as a stay against bump melting down while a heating process. Besides, the ball stabilizes a standoff between an IC chip and an IC carrier so that the RF electrical connection between them becomes stable in terms of impedance matching at higher RF bands. This mount technique has achieved the higher standoff with around 110μm, which makes higher than a low profile gold bump bonding. It is also shown that the standoff height is much better for the RF electrical chip connection by a simulation results.

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The advantages and limitations of extremely thin thermosetting adhesive film (TTAF) are discussed. The properties of TTAF with a thickness range between 5 and 35 micrometers were investigated. The strength of adhesion was found to strongly depend on the film thickness below 10 micrometers. These behaviors can be explained by the Kaelble's equation and Goland-Reissner analysis. Effect of adhesive thickness on the solder heat resistance was also measured. A model based on fracture mechanical analyses for blister test was introduced to predict the adhesive de-bonding during solder reflow. The model predicted little thickness dependence of the solder heat resistance. On the other hand, higher solder heat resistance was observed for thinner adhesive samples. Since the ultimate adhesive thickness depends on the bonding process, the flow study for TTAF is important. Novel analytical method of the adhesive flow is developed.

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A membrane-type material used in electronic circuit inspections was developed. This material can be used to produce narrow pitches at a low cost. It has a durability under repeated tests, up to 1 million runs using a QFN (Quad Flat Non-leaded package) . When examined, the characteristics of electricity, conductor resistance, insulation resistance, withstand voltage and current-carrying capacity were tested. It was confirmed that the acceptable level was achieved without any problems as a contact probe.

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