DESIGN OF MOLD MATERIALS FOR ENCAPSULATING SEMICONDUCTORS USING EPOXY COMPOUNDS

摘要

Mold materials have been found which have excellent releasabilities. This was achieved by inhibiting mold adhesion caused by acid-base interactions between epoxy molding compounds (EMCs) (used for encapsulating semiconductors) and hydroxyl groups on the mold surface. Some rare-earth oxides, which have isoelectric points of the surface (IEPS) in the range 9 to 10, have excellent releasability from EMCs. In particular, the releasing force of Y2O3 is 10 times smaller than that of conventional mold materials for alloy tool steels. It has thus received considerable attention for use as a mold material. It was found that the releasability depends on the arithmetic difference between the IEPS of the mold material and the dissociation constant of the EMC species.