Papers by Author: Kozo Fujimoto

Abstract: Fuel cell is one of the promising candidates for mobile power source. In the fuel cell, the design considering micro structure is considered to be indispensable for developing a highperformance cell. In this work, the effect of the anode electrode structural design of the DMFC (direct methanol fuel cell) on the cell performance was investigated by three-dimensional numerical simulation. The influence of diffusion layer thickness in the electrode on the mass fraction of methanol and carbon dioxide in the reaction layer is examined for various operation conditions. As a result, we clarified that the micro structure change in the electrode significantly affected the mass fraction of the species in reaction layer in the fuel cell.

Abstract: The growing importance of high integration on electronics demands novel interconnection methods replacing high-cost solder bumping or less reliable conductive adhesives. Self-organizing interconnection process using resin containing solder fillers has a possibility to achieve high-density joints satisfying both needs. Numerical study visualized the process and revealed that surface tension of molten fillers and resin viscosity determine the speed of conductive path formation.

Abstract: The novel selective interconnection using the resin containing low-melting-point-alloy fillers was developed as a high density assembly method of a low-temperature and highly reliable electronic interconnection. By means of the coalescence of fillers and wetting onto the terminal material due to the Laplace pressure of the fillers, self-organization onto the terminals was formed. The influence of the filler volume ratio and resin viscosity on the self-organized interconnecting was investigated by the numerical analysis with a multi-filler dispersion model corresponding to a real process, and was evaluated by using the normalized parameter (self-organization ratio). We clarified the existence of the optimal value of the filler volume ratio. The rate controlling factor transferred from the filler volume to the inflow velocity by the increase of the viscosity.