Discussion on Anisotropic Magnetic Shielding Effectiveness of Shielded Package Analyzed by Magnetic Circuit Calculation

Abstract

This paper presents millimeter-scale small magnetic shields for electrical components such as magnetic sensors or magnetic random-access memories (MRAM). A prototype of a shielded package consisting of two shield pieces is fabricated by using a MEMS package assembly line. The shielded package exhibits anisotropic magnetic shielding effectiveness (MSE). Two magnetic circuit models are introduced to explain the cause of the anisotropic MSE. The models reveal that magnetic flux flow and magnetic reluctances are changed by an external magnetic field, which causes anisotropic MSE.