LC filter device having magnetic resin encapsulating material

• US 5,034,710 A
• Filed: 07/21/1988
• Issued: 07/23/1991
• Est. Priority Date: 07/22/1987
• Status: Expired due to Term

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Kawaguchi, Masahiko
• Primary Examiner(s): LaRoche, Eugene R.
• Assistant Examiner(s): LEE, BENNY T
• Application Number:
  US07/222,172
• Time in Patent Office: 1,097 Days
• Field of Search: 333/185, 333/184, 336/200, 336/232
• US Class Current: 333/185
• CPC Class Codes: H03H 2001/0078 comprising spiral inductor on a substrate
• CPC Class Codes: H03H 7/0115 comprising only inductors and capacitors H03H7/075, H03H7/09, H03H7/12, H03H7/13 take precedence

Abstract

An LC filter device includes a dielectric substrate having opposing sets of coil electrode patterns and capacitor electrode patterns. Each set of coil electrode patterns forms an inductive element, and each set of capacitor electrode patterns forms a capacitive element. The inductive and capacitive elements are interconnected to form an LC circuit configuration. The dielectric substrate is encapsulated by a resin coating. The resin coating includes a magnetic material, such as a high frequency ferrite powder, to increase the inductance of the LC filter and to reduce the stray capacitance of the LC filter.

Claims

1. An LC filter device comprising:

a dielectric substrate having opposite first and second surfaces;

at least one set of opposing coil electrode patterns respectively located on said first and second surfaces of said dielectric substrate, each of said at least one set of opposing coil electrode patterns forming a corresponding inductive element;

at least one set of opposing capacitor electrode patterns respectively located on said first and second surfaces of said dielectric substrate, each of said at least one set of opposing capacitor electrode patterns forming a corresponding capacitive element;

first, second and third terminals;

means for electrically and operatively interconnecting said at least one set of opposing coil electrode patterns and said at least one set of opposing capacitor electrode patterns to said first, second and third terminals so as to form a predetermined LC filter circuit configuration made up of the inductive and capacitive elements respectively formed by said at least one set of opposing coil electrode patterns and said at least one set of opposing capacitor electrode patterns;

a resin coating encapsulating said dielectric substrate, said resin including a magnetic material so as to increase an inductance of the LC filter device, said magnetic material being 50 to 90% by weight of said resin.

2. An LC filter device as recited in claim 1, said magnetic material being a high frequency ferrite powder.