Ryoji Kitada

Study on Surface Characteristics of EDMed Surface with Nickel Powder Mixed Fluid

EDM finishing technology has progressed recently, and very small surface roughness can be obtained by controlling the electrical discharge conditions. Also, EDM using powder mixed fluids can improve the surface characteristics. Therefore, the EDM finished surface is highly expected to be applied as a final metal mold surface. In that case, the characteristics of EDMed surface influence the molding performance and the life of metal molds. As a new surface finishing method by EDM, the characteristics of EDMed surface using a nickel powder mixed fluid was experimentally discussed in this study, since nickel coatings have been widely applied to improve the corrosion resistance and the mold releasability of metal molds. Experimental analysis clarified that the resolidified layer containing nickel content could be formed on the surface by EDM in nickel powder mixed fluid. Also, the water repellency and the releasability of molded resin from the EDM finished surface could be improved.

Singulation of semiconductor package by superposition of pulsed fiber laser and green yag laser

The application of laser beam processing has been expected in the field of semiconductor devices because of its flexible cutting line and narrow kerf width. However, the deterioration of cutting quality would occur in the case of themosensitive materials due to the thermal damage, since the laser beam processing is mainly thermal process. Therefore, the laser singulation method by the superposition of pulsed fiber laser and green YAG laser was proposed to perform the high-quality processing for the semiconductor package, which is consisted of thermosetting epoxy-resin with silica for molding compounds and glass epoxy board for semiconductor package with insulator coatings. The superposition of pulsed fiber laser and green YAG laser with high pulse repetition rates led to a straighter kerf shape with smaller kerf width under the same pulse energy condition. The smaller kerf width could be achieved by controlling the time delay between both laser pulses compared with synchronized laser pulses. The heat affected zone in singulation process could be reduced by the superposition of pulsed fiber laser and green YAG laser. Moreover, the synchronized laser pulses could lead to the smaller heat affected zone compared with unsynchronized one.The application of laser beam processing has been expected in the field of semiconductor devices because of its flexible cutting line and narrow kerf width. However, the deterioration of cutting quality would occur in the case of themosensitive materials due to the thermal damage, since the laser beam processing is mainly thermal process. Therefore, the laser singulation method by the superposition of pulsed fiber laser and green YAG laser was proposed to perform the high-quality processing for the semiconductor package, which is consisted of thermosetting epoxy-resin with silica for molding compounds and glass epoxy board for semiconductor package with insulator coatings. The superposition of pulsed fiber laser and green YAG laser with high pulse repetition rates led to a straighter kerf shape with smaller kerf width under the same pulse energy condition. The smaller kerf width could be achieved by controlling the time delay between both laser pulses compared with synchronized laser pulses. The heat affe...