Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2000-08-12
2004-04-27
Tugbang, A. Dexter (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S605000, C029S606000, C029S607000, C205S205000, C205S208000, C336S192000, C336S083000, C336S206000
Reexamination Certificate
active
06725525
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an inductor and a method of producing such an inductor, and more particularly, the present invention relates to an inductor having a conductor (internal conductor) functioning as an inductance element that is located within a magnetic material produced by kneading a magnetic powder and a resin, and a method of producing the inductor.
2. Description of the Related Art
As shown in
FIG. 7
, a surface-mount inductor including a magnetic material compact body
53
that is produced by molding a magnetic material
51
obtained by kneading a magnetic powder and a resin into a mold in which a coil (internal conductor)
52
functioning as an inductance element is buried in the magnetic material
51
, with both ends
52
a
and
52
b
of the coil
52
exposed at both end surfaces of the magnetic material compact body
53
, and a pair of external electrodes
54
a
and
54
b
provided at both end surfaces of the magnetic material compact body
53
.
This inductor can be produced by molding the magnetic material
51
obtained by kneading a magnetic powder and a resin to produce the magnetic material compact body
53
, and then providing the external electrodes
54
a
and
54
b
on the magnetic material compact body
53
. Thus, the step of firing the inductor at high temperature is not necessary, which is required for conventional ceramic inductors including magnetic ceramic material. Therefore, the manufacturing cost of producing the inductor is decreased.
However, in forming the external electrodes of the above-described inductor by a method including the steps of coating conductive paste and baking it, like in ceramic inductors, the resin that constitutes the magnetic material compact body decomposes in response to the heat applied during baking of the conductive paste. Under actual conditions, it is very difficult to apply the conventional method using conductive paste without modification.
Therefore, a conventional inductor is shown in
FIG. 8
, in which metal caps
55
a
and
55
b
are mounted as external electrodes to both ends of the magnetic material compact body so as to be connected to both ends of the coil
52
. However, the metal caps are expensive and require the step of mounting the metal caps, thereby increasing production cost.
In other conceivable methods of forming the external electrodes using conductive paste, special conductive paste that can be baked at low temperature is used, or a resin having excellent heat resistance is used as the resin that constitutes the magnetic material compact body. However, both of these methods are problematic because they produce inductors with diminished and inferior properties, and decrease the ease and degree of freedom of the manufacturing process.
SUMMARY OF THE INVENTION
To overcome the above-described problems, preferred embodiments of the present invention provide an inductor in which external electrodes are efficiently provided without using metal caps or baking conductive paste, and which has high reliability of connection between the external electrodes and an internal conductor, and desired properties. Preferred embodiments of the present invention also provide a method of producing such a novel inductor.
A method of producing an inductor according to preferred embodiments of the present invention includes the steps of molding a magnetic material obtained by kneading a magnetic powder and a resin into a desired shape in which a conductor (internal conductor) functioning as an inductance element is buried to form a magnetic material compact body in which the internal conductor is partially exposed at a surface thereof, and plating the surface of the magnetic material compact body to form external electrodes including a metallic film electrically connected to the portions of the internal conductor which are exposed on the surface of the magnetic material compact body.
The method of producing an inductor according to preferred embodiments of the present invention includes molding the magnetic material obtained by kneading the magnetic powder and the resin into the desired shape to form the magnetic material compact body in which the internal conductor is partially exposed at a surface thereof, and plating the surface to form the external electrodes so that the external electrodes are electrically connected to the internal conductor. Thus, the method according to preferred embodiments of the present invention eliminates the necessity of a heat-treatment step for firing in the step of forming the magnetic material compact body, baking conductive paste in the step of forming the external electrodes, while avoiding decomposition or transformation of the magnetic material in the heat treatment step, thereby permitting the efficient production of an inductor having desired properties. Further, there is also no need for equipment such as a heat treatment furnace, or other similar equipment, and thermal energy used for heat treatment, thereby reducing production costs.
In preferred embodiments of the present invention, the step of molding the magnetic material into the predetermined shape to form the magnetic material compact body in which the internal conductor is partially exposed at a surface thereof is applicable not only where the magnetic material is molded to form the magnetic material compact body including the internal conductor partially exposed at the surface thereof, but also in methods including the step of exposing the internal conductor, such as where the magnetic material compact body is cut and ground to partially expose the internal conductor at the surface after the magnetic material is molded.
The method of producing an inductor according to preferred embodiments of the present invention further includes roughening portions of the surface of the magnetic material compact, on which plated metal films are formed by plating, before such plating is performed.
By performing plating after roughening the portions of the surface of the magnetic material compact body which are to be plated, the strength of adhesion of the plated metal film to the magnetic material compact body is greatly improved, thus significantly improving reliability.
The method of producing an inductor according to preferred embodiments of the present invention includes exposing both ends of the internal conductor at both end surfaces of the magnetic material compact body, roughening at least both end surfaces thereof, and plating at least portions of the roughened surfaces to form the external electrodes.
In the method including exposing both ends of the internal conductor at both end surfaces of the magnetic material compact body, roughening at least both end surfaces thereof, and then plating at least portions' of the roughened surfaces to form the external electrodes, the external electrodes are provided on both end surfaces of the magnetic material compact body to allow the efficient production of a chip-type inductor having excellent adaptability for surface mounting, thereby increasing the effectiveness of the present invention.
In the method of producing an inductor according to preferred embodiments of the present invention, with the internal conductor including a coiled metal conductor (coil), both end surfaces of the magnetic material compact body are roughened to expose ⅓ to 1 turn of the coil so that the coil partially projects from both end surfaces of the magnetic material compact, and then at least portions of the roughened surfaces are plated to form the external electrodes.
In the method including roughening the surface to expose about ⅓ to 1 turn of the internal conductor, which includes a coiled metal conductor (coil), so that the coil partially projects from both end surfaces of the magnetic material compact, and then forming the external electrodes by plating, a sufficient area of contact between the coil and the external electrodes is ensured, thus significantly improving reliability of electrical contact between the coil and th
Fukutani Iwao
Hamatani Junichi
Oshima Hisato
Saito Ken-ichi
Shikama Takashi
Keating & Bennett LLP
Murata Manufacturing Co. Ltd.
Tugbang A. Dexter
LandOfFree
Method of manufacturing an inductor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of manufacturing an inductor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing an inductor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3195028