Inductor and manufacturing method thereof

• US 6,373,368 B1
• Filed: 09/18/2000
• Issued: 04/16/2002
• Est. Priority Date: 09/16/1999
• Status: Expired due to Fees

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Saito, Kenichi, Oshima, Hisato, Fukutani, Iwao, Hamatani, Junichi, Shikama, Takashi
• Primary Examiner(s): DONOVAN, LINCOLN D
• Application Number:
  US09/665,243
• Time in Patent Office: 575 Days
• Field of Search: 336/200, 336/232, 336/220, 336/84, 336/90, 336/96, 296/05
• US Class Current: 336/200
• CPC Class Codes: H01F 27/027 specially adapted for combination of signal type inductors or transformers with electronic circuits, e.g. mounting on printed circuit boards
• CPC Class Codes: H01F 27/292 Surface mounted devices
• CPC Class Codes: H01F 41/005 Impregnating or encapsulating insulating of windings H01F41/12
• CPC Class Codes: H01F 41/04 for manufacturing coils coils for transformer or inductances H01F27/28
• CPC Class Codes: H01F 41/10 Connecting leads to windings making electric connections in general H01R43/00
• CPC Class Codes: Y10T 29/49071 by winding or coiling

Abstract

A method for efficiently and economically manufacturing an inductor using a resin based magnetic material, and a highly reliable inductor that is manufactured by the method, produces a unique inductor including a molded magnetic material member. An inner conductor is disposed in the molded magnetic material member and is exposed at a surface of the molded magnetic material member. The molded magnetic material member is formed using the resin based magnetic material in which a component that functions as nuclei for applying electroless plating is blended, followed by forming a selectively coated molded body so that the area not provided with external electrodes on the surface of the molded magnetic material member is covered with an insulating resin and applying electroless plating on the molded magnetic material member (selectively coated molded body), thereby eliminating use of a resist agent that is required in the conventional manufacturing method, as well as a resist agent removing step with an alkali and solvent and a removing step of the electroless plating film with an acid, by forming the electroless plating film as the external electrodes on the desired area.

Claims

1. A method for manufacturing an inductor comprising the steps of:

molding a magnetic material prepared by blending a magnetic powder with a resin into a molded body having a desired shape such that an inner conductor defining an inductance element is embedded within the molded body, thereby forming a molded magnetic material member having a portion of the inner conductor exposed at a surface thereof;

forming a resin-coated molded body having a main portion which is selectively coated with an insulating resin such that the insulating resin is coated on an entire surface of the molded magnetic material member except in a region where external electrodes are to be provided; and

forming the external electrodes including electroless plating films on the region where the external electrodes are to be formed by applying electroless plating on the resin-coated molded body.

2. A method for manufacturing an inductor according to claim 1, wherein said step of forming the external electrodes includes the step of applying multiple electroless plating films.

3. A method for manufacturing an inductor according to claim 2, wherein at least one of said multiple electroless plating films is a Ni film.

4. A method for manufacturing an inductor according to claim 2, wherein at least one of said multiple electroless plating films is an Sn film.

5. A method for manufacturing an inductor according to claim 1, wherein the external electrodes are formed by applying electroless plating after roughening the area to be provided with the external electrodes on the molded magnetic material member by a blast medium blow method for blowing a blast medium.

6. A method for manufacturing an inductor according to claim 1, wherein said electroless plating films define a structure including a plurality of layers which are formed by applying different kinds of electroless plating a plurality of times.

7. A method for manufacturing an inductor according to claim 1, further comprising a step of forming an external electrode including an upper electrolytic plating film with a monolayer or multilayer structure by additionally applying at least one type of electrolytic plating on said external electrodes.

8. A method for manufacturing an inductor comprising the steps of:

molding a magnetic material prepared by blending a magnetic powder, a resin and a component to function as nuclei for applying electroless plating into a molded body having a desired shape so that an inner conductor functioning as an inductance element is embedded within the molded body, thereby forming a molded magnetic material member having a surface at which a portion of the inner conductor is exposed;

forming a selectively coated molded body so that an area outside of an area to be provided with external electrodes on the surface of the molded magnetic material member is coated with an insulating resin; and

forming the external electrodes including electroless plating films on the area to be provided with the external electrodes by applying electroless plating on the selectively coated molded body.

9. A method for manufacturing an inductor according to claim 8, wherein the external electrodes are formed by applying electroless plating after roughening the area to be provided with the external electrodes on the molded magnetic material member by a blast medium blow method for blowing a blast medium.

10. A method for manufacturing an inductor according to claim 8, wherein said step of forming the external electrodes includes the step of applying multiple electroless plating films.

11. A method for manufacturing an inductor according to claim 10, wherein at least one of said multiple electroless plating films is a Ni film.

12. A method for manufacturing an inductor according to claim 10, wherein at least one of said multiple electroless plating films is an Sn film.

13. A method for manufacturing an inductor according to claim 8, wherein Pd is used for the component to function as nuclei for applying electroless plating.