Inductor devices – Windings – Having conductor of particular shape
Reexamination Certificate
2000-05-15
2002-05-14
Mai, Anh (Department: 2832)
Inductor devices
Windings
Having conductor of particular shape
C336S200000, C336S232000, C029S602100, C029S606000
Reexamination Certificate
active
06388550
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a chip inductor used in electronic appliances, communication appliances, and others, and its manufacturing method.
BACKGROUND ART
In
FIG. 6
to
FIG. 9
, a conventional chip inductor comprises a square columnar main body
21
made of an insulating material, a coil unit
25
having a linear conductor
23
and a groove
24
formed by spirally grooving a conductor layer
22
on the surface of the main body
21
, an exterior unit
29
made of an insulating resin
28
applied on the surface of the coil unit
25
, and an electrode unit
26
provided at the end portion of the main body
21
.
Its manufacturing method comprises a first step of forming a conductor layer
22
on a square columnar main body
21
made of an insulating material, a second step of forming a coil unit
25
having a linear conductor
23
and a groove
24
by grooving the conductor layer
22
by laser
27
, a third step of forming electrode units
26
at both ends of the coil unit
25
, and a fourth step of forming an exterior unit
29
by coating the coil unit
25
with an insulating resin
28
and drying.
Herein, at the fourth step, while rotating the main body
21
forming the coil unit
25
in the direction of arrow A in FIG.
9
(
c
), on the tape to which the insulating resin
28
is adhered, the insulating resin
28
is applied on the coil unit
25
, and the entire circumference of the coil unit
25
is coated with the insulating resin
28
.
By drying this insulating resin
28
, the exterior unit
29
is formed.
In such conventional constitution, the insulating resin
28
is applied on the surface of the coil unit
25
, but the insulating resin
28
was not applied in the inner part of the groove
24
of the coil unit
25
.
Generally, in a very small part such as chip inductor (overall dimension being about 1 mm), the interval of adjacent linear conductors
23
in the coil unit
25
is as narrow as scores of microns, and it is hard to coat the insulating resin
28
due to effects of surface tension and others of the insulating resin
28
, and coated portions and uncoated portions of the insulating resin
28
coexisted inside the groove
24
.
As a result, gaps
40
were formed inside the groove
24
as shown in
FIG. 7
, and due to air or moisture in the gaps
40
, appropriate insulation is not provided between the adjacent linear conductors
23
of the coil unit
25
, and short-circuit is caused.
Also in the conventional method, since the insulating region
28
is applied on the coil unit
25
while rotating the main body
21
forming the coil unit
25
on the tape to which the insulating resin
28
is adhered, as shown in
FIG. 8
, the insulating resin
28
applied on the coil unit
25
forms a circular profile, while surrounding the square columnar main body
21
due to the surface tension.
As a result, the mounting surface by the exterior unit
29
is round, and when mounting a packed substrate or the like, accurate mounting is difficult, and gaps
40
are likely to be formed in the groove
24
.
DISCLOSURE OF THE INVENTION
It is hence an object of the invention to present a chip inductor capable of preventing short-circuit and enhancing the electric characteristics by applying an appropriate insulation between adjacent linear conductors of the coil unit, and mounting appropriately by forming a flat mounting surface in the exterior unit, and its manufacturing method.
To achieve the object, the invention is characterized by a constitution comprising a square columnar main body made of an insulating material, electrode units disposed at both sides of the main body, a coil unit connected to the electrode units, and disposed on the outer circumference of the main body between the electrode units, and an exterior unit having the coil unit coated with an insulating resin, in which the coil unit has linear conductors and grooves formed by grooving the conductor layer applied on the surface of the main body, and the insulating resin is also provided in the entire inside of the grooves.
Its manufacturing method comprises a first step of forming a conductor layer on a square columnar main body made of an insulating material, a second step of forming a coil unit having linear conductors and grooves by grooving the conductor layer, a third step of forming electrode units at both ends of the coil unit, and a fourth step of forming an exterior unit by coating the coil unit with an insulating resin and drying, in which the fourth step is intended to form the exterior unit by first coating the coil unit formed on one side of the main body with an insulating resin and drying, then coating the coil unit formed on other side with an insulating resin and drying.
In this constitution, since the insulating resin is provided also in the entire inside of the groove, there is no gap in the groove, and air or moisture is forced out, and appropriate insulation can be applied between linear conductors, so that short-circuit can be prevented.
Also, in this method, in the coil unit formed on the surface to which the main body is adjacent, the insulating resin is applied and dried on the coil unit formed at one side, and then the insulating resin is applied and dried on the coil formed at other side, thereby forming the exterior unit. In this case, the insulating resins applied on the coil units at the adjacent sides are not formed in a circular external shape due to mutual effects of surface tension because one side is already cured. Moreover, since the area of applying and drying the insulating resin in one step is small, the surface tension is smaller, and the insulating resin is easily applied in the entire inside of the groove.
As a result, in the square columnar main body, the insulating resin is also applied in a square columnar form, and an exterior unit of square columnar form is fabricated, and the mounting surface on the exterior unit is flat, and mounting on packed substrate or the like is improved, and the insulating resin may be easily applied to the entire inside of the groove of the coil unit.
REFERENCES:
patent: 3812442 (1974-05-01), Muckelroy
patent: 5441783 (1995-08-01), Silgailis et al.
patent: 5764126 (1998-06-01), Kanetaka et al.
patent: 0 065 147 (1982-04-01), None
patent: 0 785 559 (1997-07-01), None
patent: 06-215950 (1994-08-01), None
patent: 9-55321 (1997-02-01), None
Fujimori Akira
Kanetaka Toyonori
Nakayama Hideaki
Taoka Mikio
Yoshizawa Toshihiro
Mai Anh
Matsushita Electric - Industrial Co., Ltd.
McDermott & Will & Emery
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