PURPOSE: To obtain a shielding material having a superior shielding effect to an electromagnetic wave of a wide frequency band by a method wherein a conductive metal film is applied on a soft magnetic powder piece having a high magnetic permeability and a low coercive force.
CONSTITUTION: A conductive metal film is applied on a soft magnetic powder piece having a high magnetic permeability and a low coercive force. As the split magnetic powder piece, a silicon steel, sendust alloy, permaalloy alloy or Co or Fe amorphous alloy powder piece and a ferrite oxide powder piece are used. The mean particle diameter of the powder pieces is confined to a range of about 1μm to 5cm. As the conductive metal film, a copper, silver, nickel, gold or palladium film or a film made of an alloy consisting of these metals is used. When the copper, silver or nickel film is covered using an Fe soft magnetic alloy powder piece having a mean particle dismeter of 5 to 200μm and an accept ratio of 10 to 50, this covering amount is confined to about 5 to 75wt.% per unit weight of the covering powder piece. Thereby, a shielding material having a superior shielding effect to an electromagnetic wave of a wide frequency band is obtained.
IMAI HIROYUKI
MIYAKE MASAMI
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