Inductor devices – Coil or coil turn supports or spacers – Printed circuit-type coil
Reexamination Certificate
2000-09-18
2002-04-16
Donovan, Lincoln (Department: 2832)
Inductor devices
Coil or coil turn supports or spacers
Printed circuit-type coil
C029S605000
Reexamination Certificate
active
06373368
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an inductor and a method for manufacturing thereof. More particularly, the present invention relates to an inductor having external electrodes disposed at a certain position on a molded magnetic material member so as to be electrically connected to inner electrodes embedded within a molded magnetic material member.
2. Description of the Related Art
As shown in
FIG. 12
, a surface mounting type inductor includes a coil (an inner conductor)
52
that functions as an inductance element embedded in a resin based magnetic material
51
made by blending a magnetic powder and a resin to produce a molded magnetic material member
53
having at two terminal surfaces, terminals
52
a
and
52
b
of the coil
52
which are exposed, and a pair of external electrodes
54
a
and
54
b
are arranged to be electrically connected to the terminals
52
a
and
52
b
of the coil
52
.
This inductor may be manufactured by providing the external electrodes
54
a
and
54
b
on the molded magnetic material member
53
made by molding the resin based magnetic material
51
produced by blending a magnetic power and a resin. This inductor requires no firing process at a high temperature as has been required in ceramic inductors using conventional magnetic ceramics, thus facilitating the manufacture of the inductor.
The inductor using the resin based magnetic material as described above is manufactured, for example, by the following steps.
(1) Preparing a ferrite powder (a magnetic powder), ferrite-resin pellets (a magnetic material) prepared by kneading the ferrite powder with a resin, and a coil (an inner conductor) produced by molding a copper wire (an AIW wire) coated with an insulating resin (a polyamide-imide resin) into a coil.
(2) Then, a ferrite-resin molded body (a molded magnetic material member)
53
is formed, wherein the coil (the inner conductor)
52
that functions as an inductor element is embedded within the magnetic material
51
as shown in
FIG. 6
by injection molding of the ferrite containing resin around the coil after allowing the ferrite-resin pellets to melt by heating.
(3) Subsequently, sand-blasting is performed on the area (the both terminal surfaces of the molded magnetic material member
53
) on which external electrodes
54
a
and
54
b
(see
FIG. 12
) are to be provided on the surface of the molded magnetic material member
53
as shown in
FIG. 7
to expose both terminals
52
a
and
52
b
(see
FIG. 12
) of the coil
52
from the molded magnetic material member
53
, and removing an insulating coating film (a polyamide imide resin) on the coil
52
.
(4) Subsequently, a Ni electroless plating is applied after applying a nucleation treatment for the electroless plating on the molded magnetic material member
53
, and a Ni electroless plating film
55
is formed on the entire surface of the molded magnetic material member
53
as shown in FIG.
8
.
(5) In the next step, a resist agent
56
is coated on the area as shown in
FIG. 9
where the external electrodes
54
a
and
54
b
(see
FIG. 12
) are to be provided on the molded magnetic material member
53
, the entire surface of which is covered with the Ni electroless plating film, and the resist film is dried.
(6) Then, the Ni electroless plating film
55
at the unnecessary portion on the surface of the molded magnetic material member
53
is removed by etching with an acid as shown in FIG.
10
.
(7) Subsequently, the resist agent
56
is removed with an alkali (FIG.
11
).
(8) Then, a Ni electroplating film
57
is formed on the Ni electroless plating film
55
as shown in
FIG. 12
by applying a Ni electroplating on the molded magnetic material member
53
. Finally, a Sn electroplating film
58
is further formed on the plating films
55
to form the three layered external electrodes
54
a
and
54
b
including the Ni electroless plating film
55
, the Ni electroplating film
57
, and the Sn electroplating film
58
.
In the process for manufacturing the inductor using the foregoing resin-based magnetic material, the Ni electroless plating film
55
is provided on the entire surface of the molded magnetic material member
53
, and the resist agent
56
is coated on the area where the external electrodes
54
a
and
54
b
(
FIG. 12
) are to be provided, followed by removing the resist agent
56
with an alkali after removing the unnecessary Ni electroless plating film
55
by etching with an acid. Consequently, the manufacturing process involves many steps thus complicating the process, as well as increasing the manufacturing costs. Moreover, the process requires a lot of labor to process unnecessary products generated in the etching step using an acid for removing the unnecessary portion of the Ni electroless plating film, and the step for removing the resist agent using an alkali.
SUMMARY OF THE INVENTION
To overcome the above-described problems, preferred embodiments of the present invention provide a method for efficiently manufacturing an inductor using a resin-based magnetic material, and further provide a reliable inductor at greatly reduced costs.
A first preferred embodiment of the present invention provides a method for manufacturing an inductor including the steps of molding a magnetic material prepared by blending a magnetic powder with a resin into a molded body having a desired shape so that an inner conductor that functions as an inductance element is embedded within the molded body, thereby forming a molded magnetic material member having a portion of the inner conductor exposed on a surface thereof, forming a selectively coated molded body (a molded body having a main portion that is selectively coated with an insulating resin) so that the areas on the surface of the molded magnetic material member except for the area to be provided with external electrodes is coated with the insulating resin, and forming the external electrodes including an electroless plating film on the area to be provided with the external electrodes (the area where the insulating resin is not coated) by applying electroless plating on the selectively coated molded body such that the external electrodes are electrically connected to the inner conductor.
In the method for manufacturing the inductor described above, after forming the molded magnetic material member, having the portion of the inner conductor exposed at a surface thereof, by using a resin based magnetic material, the selectively coated molded body is formed so that the area not provided with the external electrodes on the surface of the molded magnetic material member is covered with the insulating resin. The external electrodes are formed at desired areas by applying electroless plating film on the molded magnetic material member (the selectively coated molded body).
Consequently, a resist agent used in conventional manufacturing methods is not required in the present invention. As a result, the steps for removing the resist agent with an alkali or a solvent (simply referred as a liquid chemical hereinafter) and the steps for removing the electroless plating films by etching with acid are eliminated. Therefore, the manufacturing process of preferred embodiments of the present invention is greatly simplified and greatly reduces the manufacturing costs and the labor involved in manufacturing.
A second preferred embodiment of the present invention provides a method for manufacturing an inductor including the steps of molding a magnetic material prepared by blending a magnetic powder, a resin and a component functioning as nuclei for applying electroless plating into a molded body having a prescribed shape so that an inner conductor that functions as an inductance element is embedded within the molded body, thereby forming a molded magnetic material member having a portion of the inner conductor exposed on a surface thereof, forming a selectively coated molded body so that the area on the surface of the molded magnetic material member except for the area to be provided with external
Fukutani Iwao
Hamatani Junichi
Oshima Hisato
Saito Ken-ichi
Shikama Takashi
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