A pyrolysis-based technology for recovering useful materials from IC package molding resin waste

This paper describes a pyrolysis-based technology for recovering useful materials from molding resin waste, which is the main type of thermosetting plastic waste generated in the fabrication of IC packages. In our pyrolysis of molding resin waste, the main impurities in the recovered silica were carbon (C), antimony (Sb) and phosphoric acid ion (PO/sub 4//sup 3/). The amount of carbon and phosphoric acid ion decreased with increased heating temperature and oxygen concentration. However, the antimony remained constantly between 400 and 1000/spl deg/C because diantimony tetraoxide (Sb/sub 2/O/sub 4/), which is hard to volatilize, was formed by oxidation. Our experimental results suggest that the most effective way to reduce the impurities is to heat at between 1000-1100/spl deg/C and to keep oxygen concentration at about 8 vol%. On the basis of these results, we used a roller kiln type furnace as a prototype practical pyrolysis system for recovering high purity silica. The purity achieved was as follows: C