Inductor and manufacturing method therefor

• US 20020067232A1
• Filed: 09/10/2001
• Published: 06/06/2002
• Est. Priority Date: 09/08/2000
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Shikama, Takeshi, Oshima, Hisato, Hamatani, Junichi, Saito, Kenichi, Fukutani, Iwao
• Granted Patent: US 6,859,994 B2
• Time in Patent Office: Days
• US Class Current: 336/96
• CPC Class Codes: H01F 27/292 Surface mounted devices
• CPC Class Codes: H01F 27/327 Encapsulating or impregnating encapsulating coil and core H01F27/022
• CPC Class Codes: H01F 41/005 Impregnating or encapsulating insulating of windings H01F41/12
• CPC Class Codes: H01F 41/122 Insulating between turns or between winding layers
• CPC Class Codes: H01F 41/127 Encapsulating or impregnating encapsulating coil and core H01F41/005
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor
• CPC Class Codes: Y10T 29/49071 by winding or coiling
• CPC Class Codes: Y10T 29/49076 From comminuted material
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing

Abstract

An inductor which has a superior shape retaining property of a coil conductor, is superior in mass-productivity, and can be applied to an automated manufacturing line, and a manufacturing method therefor are provided. The surface of a metal wire provided with an insulating film thereon is coated with a thermal melting resin. The thickness of the thermal melting resin is, for example, approximately 1 μm. As the thermal melting resin, a thermoplastic resin or a thermosetting resin, such as a polyimide resin or an epoxy resin, containing 85 wt % of a powdered ferrite is used. This coated metal wire is densely wound to form a solenoid-type coil conductor. Next, the thermal melting resin is softened by a heat treatment at, for example, 180° C. and is then solidified by spontaneous cooling. Accordingly, the portions of the coil conductor adjacent to each other are bonded together by the thermal melting resin.

Claims

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

coating a surface of a metal wire having an insulating film thereon with a thermal melting resin to form a coated metal wire;

winding the coated metal wire to form a solenoid-type coil conductor;

performing a heat treatment on the coil conductor to soften the thermal melting resin so that portions of the coil conductor that are adjacent to each other are bonded together by the thermal melting resin;

molding a resin containing magnetic powder into an encapsulating molded body having a predetermined shape so as to encapsulate the coil conductor; and

providing external terminal electrodes on surfaces of the encapsulating molded body so as to be electrically connected with the ends of the coil conductor.

2. A method for manufacturing an inductor according to claim 1, wherein the thermal melting resin includes magnetic powder.

3. A method for manufacturing an inductor according to claim 1, wherein the metal wire has a diameter of about 200 μ

m.

4. A method for manufacturing an inductor according to claim 1, wherein the metal wire includes a material selected from the group consisting of Ag, Pd, Pt, Au, and Cu.

5. A method for manufacturing an inductor according to claim 1, wherein the insulating film is made of one of a polyester resin and a polyamide-imide resin.

6. A method for manufacturing an inductor according to claim 1, wherein the thickness of the thermal melting resin is approximately 1 μ

m.

7. A method for manufacturing an inductor according to claim 1, wherein the thermal melting resin includes one of a thermosetting resin and a thermoplastic resin.

8. A method for manufacturing an inductor according to claim 1, wherein the thermal melting resin includes one of an epoxy resin and a polyimide resin, containing powdered ferrite at a ratio of about 85 wt %.

9. A method for manufacturing an inductor according to claim 1, wherein the step of performing the heat treatment includes softening the thermal melting resin by heating the coil conductor at a temperature of about 180°

C.

10. A method for manufacturing an inductor according to claim 9, further comprising the step of solidifying the thermal melting resin via cooling the thermal melting resin after the heat treatment.

11. A method for manufacturing an inductor according to claim 1, wherein the step of molding includes using a molding compound that is formed by compounding one a synthetic resin and a polyethylene terephthalate resin as a primary component, a dispersing agent, and a powdered Ni-Cu-Zn-based ferrite.

12. A method for manufacturing an inductor according to claim 1, further comprising the step of removing the resin containing the powdered ferrite at both ends of the encapsulating molded body before the step of providing the external terminal electrodes.

13. A method for manufacturing an inductor according to claim 1, wherein the step of providing the external terminal electrodes includes forming an electroless plating film on ends of the encapsulating molded body, forming a resist on both ends of the encapsulating molded body, removing unnecessary portions of the electroless plating film, and removing the resist.

15. An inductor according to claim 14, wherein the solenoid-type coil conductor includes a metal wire and the metal wire has a diameter of about 200 μ

m.

16. An inductor according to claim 15, wherein the metal wire includes a material selected from the group consisting of Ag, Pd, Pt, Au, and Cu.

17. An inductor according to claim 14, wherein the thermal melting resin includes one of a thermosetting resin and a thermoplastic resin.

18. An inductor according to claim 14, wherein the thickness of the thermal melting resin is approximately 1 μ

m.

19. An inductor according to claim 14, wherein the thermal melting resin includes one of an epoxy resin and a polyimide resin, containing powdered ferrite at a ratio of about 85 wt %.

14. An inductor comprising:

an encapsulating molded body including a resin containing magnetic powder;

a solenoid-type coil conductor encapsulated in the encapsulating molded body; and

external terminal electrodes provided on surfaces of the encapsulating molded body and which are electrically connected to ends of the coil conductor;

wherein the coil conductor is coated with a thermal melting resin and adjacent portions of the coil conductor are bonded together by the thermal melting resin, and

the inside and the outside of the solenoid portion of the coil conductor are filled with the resin containing the magnetic powder.