Multi-layered inductor array

Details Multi-layered inductor array Multi-layered inductor array

2000-09-28

2002-08-20

Mai, Anh (Department: 2832)

Inductor devices

Coil or coil turn supports or spacers

Printed circuit-type coil

C336S223000, C336S232000

Reexamination Certificate

active

06437677

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multi-layered inductor array including a plurality of inductors.
2. Description of the Related Art
A conventional multi-layered inductor array
1
is shown in FIG.
5
. The multi-layered inductor array
1
includes magnetic sheets
2
having coil conductors
3
a
to
6
e
provided thereon. The coil conductors
3
a
to
3
e
are electrically connected in series to each other through via-holes
12
formed in the magnetic sheets
2
to define a spiral inductor L
1
. Similarly, coil conductors
4
a
to
4
e
,
5
a
to
5
e
, and
6
a
to
6
e
are also electrically connected in series to each other through the via-holes
12
formed in the magnetic sheets
2
to define spiral inductors L
2
, L
3
, and L
4
, respectively.
The individual magnetic sheets
2
, as shown in
FIG. 5
, are laminated together, and on the upper and lower portions of the laminated magnetic sheets
2
, magnetic cover sheets (not shown) having no conductors provided on the surfaces thereof are disposed. Then, the laminated magnetic sheets
2
are integrally fired to define a multi-layered structure
15
as shown in FIG.
6
. On the front and back side-surfaces of the multi-layered structure
15
, external electrodes
21
a
to
24
a
and
21
b
to
24
b
of the inductors L
1
to L
4
are disposed, respectively.
In the multi-layered inductor array
1
, to reduce the size of the inductor array
1
, when the inductors L
1
to L
4
are arranged close to each other in the multi-layered structure
15
, independence between the magnetic paths of the inductors L
1
to L
4
is reduced, and as a result, magnetic couplings between the inductors L
1
to L
4
occur. Thus, the inductors L
1
to L
4
in the multi-layered structure
15
have different inductance values.
As shown in
FIG. 7
, since the magnetic paths of the spiral inductors L
1
and L
4
disposed on the right and left end surfaces of the multi-layered structure
15
are narrower at the end surfaces thereof, the inductance values of the inductors L
1
and L
4
are reduced. To solve this problem, the number of winding turns of the spiral inductors L
1
and L
4
is increased as compared to that of the spiral inductors L
2
and L
3
, and the diameters of the spiral portions of the inductors L
1
and L
4
are increased as compared to those of the inductors L
2
and L
3
, to compensate for the reduction of the inductance values. However, since the lengths of the coil conductors of the inductors L
1
and L
4
are different from the lengths of the coil conductors of the inductors L
2
and L
3
, the DC resistance values of the inductors L
1
to L
4
differ.
SUMMARY OF THE INVENTION
In order to overcome the above-described problems, preferred embodiments of the present invention provide a multi-layered inductor array that minimizes variations in the inductance values and DC resistance values of three or more inductors provided in a multi-layered structure.
According to a preferred embodiment of the present invention, a multi-layered inductor array includes a multi-layered structure defined by a laminated body of a plurality of magnetic layers and a plurality of coil conductors, at least three spiral inductors provided by electrically connecting the coil conductors to be aligned inside the multi-layered structure, and external electrodes disposed on surfaces of the multi-layered structure that are electrically connected to leading end portions of the plurality of spiral inductors. In this multi-layered inductor array, the plurality of spiral inductors have an equal number of winding turns, and, in the direction in which the spiral inductors are aligned, the lengths of the spiral portions of the inductors positioned at both end portions of the multi-layered structure shorter than the length of the spiral portion of the remaining spiral inductor.
Because magnetic paths of the spiral inductors positioned at both end portions of the multi-layered structure are narrow on the end surfaces thereof, the inductance values of the inductors is reduced. However, since the lengths of the spiral portions of these inductors positioned at both end portions of the multi-layered structure are shorter than the length of the spiral portion of the remaining inductor, the inductance values of the spiral portion of the remaining inductor is adjusted to also be reduced. Thus, variations in the inductance values between the spiral inductors are greatly suppressed.
Other features, elements, characteristics and advantages of preferred embodiments of the present invention will become apparent from the following detailed description of preferred embodiments thereof with reference to the attached drawings.


REFERENCES:
patent: 5850682 (1998-12-01), Ushiro
patent: 6191667 (2001-02-01), Takenaka et al.
patent: 11-16738 (1999-01-01), None
patent: 11-54331 (1999-02-01), None

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