Development of magnetic molding compound for low pressure molding inductors with both good magnetic properties and high reliability

By applying semiconductor encapsulation technology and optimizing magnetic powder and resin design, it has succeeded in developing a magnetic molding material (MMC) with good magnetic properties even under low pressure of several tens of MPa, such as transfer molding (T-mold). It is confirmed that toroidal rings molded by T-mold (MMC/T-mold) achieved higher density than those molded by high-pressure molding (MMC/High Press), even though the molding pressure is less than a tenth. MMC/T-mold is confirmed to have 26% higher relative permeability (μr') and 22% lower core loss (Pcv) than MMC/High Press. Furthermore, by increasing the magnetic powder content of MMC, the magnetic properties of MMC/T-mold are significantly improved, and the difference in properties between MMC/T-mold and MMC/High Press is found to be significant. These are considered to depend on the high soft magnetic properties of the amorphous alloy powder and the heat-melting and thermosetting properties of the epoxy resin.