Papers by Author: Takashi Hasegawa

Abstract: General thermometers pose difficulty in measuring the actual surface temperature of a micro-area, especially in electronic devices. In the present study, an approach to direct measurement of surface temperature is described, which utilizes the potential of melting point of different chemical reagents. The present technique exhibits a temperature resolution of about 5○C and the measurable maximum temperature of about 200○C. A short comment on the application of the technique to determine the actual surface temperature of small areas in some engineering applications
is also stated.

Abstract: Solder is the most frequently used alloy, which serves as the bonding metal for electronics components. Recently, the interconnected bump is distinctly downsizing its bulk along with the integration of high-density packaging. The evaluation of electromigration damage for solder bumps is indispensable. Hence, it is fairly urgent to understand the mechanism of the electromigration damage to be capable of securing reliability of the solder bump and ultimately predicting its failure lifetime. Electromigration pattern in multi-phase material is determined by the combination of current density, temperature and current-applying time. In this paper, diagram of electromigration pattern (DEP) in solders is presented, where both of eutectic Pb-Sn and Pb-free solders are treated. DEP gives the basis for discussing and predicting the electromigration damage in solders.