A study on wideband suppression of noise radiated from switching power supply

In this paper, a lamination of a magnetic sheet and a copper sheet is proposed to obtain wideband shielding effect from kHz to MHz bands. The requirement of the laminated magnetic sheet was discussed. A cap type shield case applying the laminated sheet 53 μm thick was fabricated and its shielding effect was measured. The higher shielding effect was obtained using the proposed sheet in the frequency range from 0.2 MHz to 6 MHz compared with that of the copper case of 70 μm, and it was improved by 15 dB at 0.2 MHz.