| 摘要 |
PROBLEM TO BE SOLVED: To provide a dust core suitable for application in a low to medium frequency range, having doubly a high magnetic permeabilityμm for realizing high-speed response, and also to provide a high mechanical strength satisfactory for a practical product. SOLUTION: The dust core is characterized in that 0.01-2 mass% of a resin composite has a kick-off temperature of 5% mass reduction at 500°C or above, and the remainder consists of soft magnetic powder with the surface covered with a phosphate compound film, wherein the resin composite contains, as an essential component, polyimide given by general Formula (1); and in the Formula (1) R<SP>1</SP>denotes a quadrivalent aromatic radical or aliphatic radical, or a quadrivalent organic radical having a plurality of aromatic radicals or aliphatic radicals bonded through single bonds, -O-, -CO-, -SO<SB>2</SB>-, -CH<SB>2</SB>- and -C(CF<SB>3</SB>)<SB>2</SB>-; and R<SP>2</SP>denotes a divalent aromatic radical or aliphatic radical, or a divalent organic radical, having a plurality of aromatic radicals or aliphatic radicals bonded through single bonds, -O-, -CO-, -SO<SB>2</SB>-, -CH<SB>2</SB>- and -C(CF<SB>3</SB>)<SB>2</SB>-, n being an integer at least 1. COPYRIGHT: (C)2006,JPO&NCIPI
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