Method of manufacturing a magnetic element
There are provided a magnetic element capable of enhancing magnetic permeability of a magnetic member, improving a direct current superposition characteristic, and improving production efficiency and a method of manufacturing the magnetic element. The magnetic element includes a coil ( 30 ) formed of a conductor having an insulating film, a first core member ( 20 ) constituted of insulative soft magnetic ferrite and covering the coil ( 30 ), and a second core member ( 50 ) having soft magnetic metal powder as material and surrounded by the first core member ( 20 ). Furthermore, the magnetic element includes a third core member ( 40 ) which has soft magnetic metal powder as material and a higher filling ratio of the soft magnetic metal powder than the second core member 50 and is surrounded by the first core member ( 20 ).
1. A method of manufacturing a magnetic element, comprising the steps of:
(a) forming a coil; said coil having end portions;
(b) molding and sintering a ferrite core; said ferrite core having a bottom portion and a side wall; said side wall having cut-out portions corresponding to the number of end portions of said coil and wherein said cut-out portions do not extend the height of said side wall;
(c) polishing said ferrite core after said sintering step;
(d) forming terminal electrodes outside of said ferrite core;
(e) placing said coil into said ferrite core with said end portions extending through said cut-out portions,
(f) mixing magnetic metal powder and resin to form a paste;
(g) forming a dam frame on said cut-out portion of said ferrite core to prevent said mixing paste from contacting with said terminal electrodes;
(h) filling said paste into said ferrite core to cover said coil so that an upper surface of said ferrite core and an upper surface of said paste form a flat surface and
(i) curing said mixing paste.
2. The method of manufacturing a magnetic element according to claim 1 , wherein said mixing paste and said terminal electrodes are not in contact with each other.
3. The method of manufacturing a magnetic element according to claim 1 , wherein said coil is formed by patterning metal on a heat resistant resin film.
4. The method of manufacturing a magnetic element according to claim 1 , wherein in said mixing paste, 75 vol % to 95 vol % is magnetic metal powder and 25 vol % to 5 vol % is resin.
5. The method of manufacturing a magnetic element according to claim 1 , wherein between windings of said coil, the mixing paste does not exist.
6. The method of manufacturing a magnetic element according to claim 1 , wherein the terminal electrodes are plated for preventing solder corrosion and securing solder wetting.