Inductor devices – Coil or coil turn supports or spacers – Printed circuit-type coil
Reexamination Certificate
2000-04-03
2003-06-17
Donovan, Lincoln (Department: 2832)
Inductor devices
Coil or coil turn supports or spacers
Printed circuit-type coil
C336S083000, C336S192000
Reexamination Certificate
active
06580350
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a laminated electronic component; and, more particularly, to a laminated electronic component including a plurality of dielectric sheets laminated on top of another, each of the sheets having a conductive pattern, and through-holes, wherein each of the through-holes having an elongated shape along a lengthwise direction of the conductive pattern, and the conductive patterns are electrically connected through the through-holes.
DESCRIPTION OF THE PRIOR ART
A prior art laminated inductor is disclosed in
FIGS. 9 and 10
, wherein
FIG. 9
offers an exploded perspective view of the laminated inductor and
FIG. 10
gives a top planar view of a ferrite sheet incorporated therein.
The laminated inductor is provided with a laminated body of a substantially rectangular shape having therein internal electrodes forming a coil and a pair of external electrodes formed at both ends of the laminated body, respectively, the external electrodes being electrically connected to the internal electrode. The internal electrode forms the coil which is wound to allow a direction of a magnetic flux generated by the coil to be substantially identical to a direction in which the external electrodes are connected. Both ends of the coil are extracted out of the laminated body to be connected to the external electrodes, respectively.
The laminated body is made of magnetic material such as a ferrite. As shown in
FIG. 9
, the laminated body
101
is formed by pressing the plurality of the laminated ferrite sheets in a direction in which the external electrodes are connected. A conductive pattern
103
is formed on each of the ferrite sheets
102
. The conductive patterns on the vertically adjacent sheets are electrically connected to one another through the through-hole
104
. The conductive pattern is formed by applying a conductive paste on the ferrite sheet
102
having the through-hole
104
. During the applying of the conductive paste, the conductive paste is charged through the through-hole
104
. Accordingly, an electrical connection is achieved between the vertically adjacent ferrite sheets
102
.
As shown in
FIG. 10
, the conductive pattern
103
has a substantially one end-opened rectangular shape at a center of each of the ferrite sheets, with one end thereof having a land
105
for an electrical connection with the through-hole
104
. Further, the conductive pattern
103
is formed to have only the land
105
at both ends of the laminated body in order to extract the coil to a surface of the laminated body.
In such an inductor, it is important to guarantee a stable electrical connection between the conductive patterns through the through-hole. Especially, in the laminated inductor where the ferrite sheets are laminated and pressed in a direction in which the external electrodes are connected, it is difficult to guarantee the stable electrical connection, since the number of electrical connections through the through-hole is increased. Important cause of the unstable connection in the electrical connection through the through-hole may result from a misalign of the ferrite sheets therebetween. The misalign of one ferrite sheet from other ferrite sheet may further reduce a contact area between the conductive pattern and the through-hole, which causes the contact resistance to increase, thereby permitting a reduced amount of the current to be flown therethrough.
In order to solve such problem, the prior art laminated inductor
100
has the land
105
formed around a portion which is connected through the through-hole
104
. A diameter of the land
105
is larger than a width of the conductive pattern serving as the coil; and is large enough to surround the through-hole
104
. In this configuration, the electrical connection together with the necessary contact area between the land
105
and the through-hole
104
can be stably guaranteed, even if the ferrite sheets are misaligned with one another within an acceptable range.
In the prior art laminated inductor, however, the conductive pattern
103
does not have an ideal shape forming the coil due to the shape of the land
105
; and a self resonant frequency(f
0
) is reduced due to an increase of a floating capacity between the land
105
and the external electrode.
SUMMARY OF THE INVENTION
It is, therefore, a primary object of the invention to provide a laminated electronic component wherein an stable electrical connection between electrodes can be guaranteed, maintaining its electrical properties.
The above and other objects of the invention are accomplished by providing a laminated electronic component having a plurality of insulating layers each of which is provided with a conductive patterns forming an internal electrode, said component comprising an elongated through-hole elongated along a length of the conductive pattern and connecting the conductive patterns on different insulating layers.
In the laminated inductor constructed in this manner, since the elongated through-hole is a hole elongated along a length of a branch of the coil conductive pattern, the electrical connection between the coil conductive patterns or between a coil conductive pattern and a lead conductive pattern can be maintained without necessitating a land for connecting to the normal through-hole. For this reason, increasing of a floating capacitance or reduction of a self-resonant frequency which may occur due to an existence of the land can be prevented. This configuration can cover more serious degrees of misalignment between the insulating layers, maintaining a sufficient contact area between the conductive patterns.
In accordance with another feature of the present invention, in the laminated electronic component, a lengthwise direction of the elongated through-hole is at a right angle with a direction of the conductive pattern formed on a directly lower insulating layer than that having the elongated through-hole. The present invention can accommodate a misalignment between the elongated through-hole and the insulating layers, maintaining a sufficient contact area therebetween.
In accordance with another feature of the present invention, in the laminated electronic component, the plurality of internal electrodes form a coil. Further, the laminated electronic component further comprises a pair of external electrodes being electrically connected to both ends of the coil, respectively, the external electrodes positioned parallel to a direction of a magnetic flux generated by the coil.
REFERENCES:
patent: 3812442 (1974-05-01), Muckelroy
patent: 4543553 (1985-09-01), Mandai et al.
patent: 5-135949 (1993-06-01), None
patent: 6-53050 (1994-02-01), None
patent: 6-69040 (1994-03-01), None
Donovan Lincoln
Katten Muchin Zavis & Rosenman
Nguyen Tuyen T.
Taiyo Yuden Co. Ltd.
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