Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2000-08-10
2004-01-13
Arbes, Carl J. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S606000, C029S609000, C336S200000
Reexamination Certificate
active
06675462
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multi-laminated inductor used for various circuits and a manufacturing method and more particularly to a multi-laminated inductor comprised of laminated internal conductors forming a coil along the length of the chip.
2. Description of the Related Art
Conventional multi-laminated inductors are classified into two broad categories in the relation between the direction of laminating internal conductors and the outside shape of the chip, which form the coil. For example, multi-laminated chip inductors have such a structure that coil-shaped internal conductors made of silver or silver-palladium alloy are contained in a nonconductor material or ferrite magnetic material and both ends of the coil are connected to external terminal conductors respectively.
FIG. 2
shows a relation between the direction of laminating internal conductors and the outside shape of the chip in this type of multi-laminated chip inductors. It has one structure that the internal conductors
2
are laminated along the thickness Lt (or width Lw) of the multi-laminated chip inductor
1
. Usual multi-laminated chip inductors have this structure. Here, the both ends of a coil-shaped conductor are connected to external terminal conductors
3
a
and
3
b
, respectively.
On the other hand, Japanese Patent Application Laid-Open No. 8-55726 teaches the another structure of a multi-laminated chip inductor
6
as shown in FIG.
3
. That is, internal conductors
4
are laminated along the length L
1
of the chip
6
and are external terminal conductors
5
a
and
5
b
formed at both end portions along its length.
This structure is generally referred to as a longitudinal stack type, and has features that it can provide relatively high inductance values and high self-resonance frequencies.
multi-laminated chip inductor of the longitudinal stack type, which has been developed applicant's assignee and is of a type disclosed in the co-pending, commonly assigned Ohno et al application, Ser. No. 09/240,699, filed Feb. 2, 1999, now U.S. Pat. No. 6,304,164, has a laminated structure as shown in
FIG. 4
, for example. That is, a coil is formed by laminating a plurality of magnetic material sheets
7
a
and
7
b
having internal conductor patterns
4
a
and
4
b
shaped like a letter L thereon, and then connecting the internal conductors
4
a
and
4
b
through via holes
8
a
and
8
b
into the shape of a spiral. Further, both ends of the coil formed by the internal conductor patterns
4
a
and
4
b
are connected to via holes
8
c
and
8
d
formed in a plurality of laminated magnetic material sheets
7
c
and
7
d
, respectively.
Thereby, lead conductor portions are formed by coupling a plurality of via holes
8
c
and
8
d
. The via holes
8
c
and
8
d
exposed to the surfaces of the magnetic material sheets
7
c
and
7
d
placed at both ends are connected to the external terminal electrodes
5
a
and
5
b
. These external terminal conductors
5
a
and
5
b
are formed on the both end faces along the length of the chip and on portions of the faces adjacent to these end faces.
In the conventional multi-laminated chip inductors
6
of the longitudinal stack type described above, the external terminal electrodes
5
a
and
5
b
are formed on both end faces along the chip length in which are perpendicular to the winding center-line of the coil formed by internal conductors
4
.
Therefore, when the magnetic flux generated by the passage of electric current through the coil passes through the external terminal electrodes
5
a
and
5
b
, eddy current is generated within the external terminal electrodes
5
a
and
5
b
. This eddy current has been one of the factors that increase its electrical loss.
Further, as the internal conductors
4
and the external terminal electrodes
5
a
and
5
b
are disposed nearly parallel to each other, stray capacity is produced between them. This stray capacity has been one of the factors behind a reduction in the self-resonance frequency of the inductors.
Also, in manufacturing of multi-laminated chip inductors of the longitudinal stack type described above, there has been no approach for adjusting a value of inductance except re-designs such as changing the core area. It has been also necessary to change the content of design for each different value of inductance. Thus, the control of design specification has been very complex.
BRIEF SUMMARY OF THE INVENTION
Considering the problems described above, it is an objection of the present invention to provide a multi-laminated inductor and a method for manufacturing it which allow reducing eddy current generated within an external terminal electrode and further an easy adjustment/modification of a value of inductance.
In order to achieve the objective described above, by providing a lead layer having a lead internal conductor exposed to a chip surface nearly parallel to the winding center-line of a coil and connected to an end of the coil for a predetermined layer, and forming an external terminal electrode formed on a face nearly parallel to the winding center-line of the coil and connected to the lead internal conductor, a multi-laminated inductor having the chip with a laminated structure having the coil buried therein and the external terminal electrode formed on the chip surface and connected to the coil is configured.
According to this multi-laminated inductor, the external terminal electrodes are formed on the faces parallel to the winding center-line of a coil, so that the magnetic flux generated by the passage of electric current through the coil does not intersect the external terminal electrodes surface. Thus, eddy current within the external terminal electrodes is prevented from generating, and so increasing the loss generated by the eddy current can be suppressed.
Also, by providing a lead internal conductor exposed to all the faces parallel to the winding center-line of a coil, it is not necessary to select a face having the external terminal electrode exposed therein at the production of the coil, so that the manufacturing process can be simplified.
Also, according to the invention , the multi-laminated inductor described above is provided with a chip shaped like a rectangular solid which has square-shaped insulating material sheets laminated therein and further provided with a lead layer comprising an insulating material sheet having a first lead internal conductor formed thereon and an insulating sheet having a second lead internal conductor formed thereon; wherein the first lead internal conductor is formed like a cross shape with a predetermined width and has its intersection point at the center of the insulating material sheet and their four edges reach to the four edges of the insulating material, and the second lead internal conductor is formed like a linear shape with a predetermined width and placed so that one end thereof is connected to the first lead internal conductor nearly at the center of the insulating material sheet and the other end thereof is connected to a predetermined spot of the end of the coil.
According to this multi-laminated inductor, the coil and the external terminal electrode are electrically connected by means of the first and second lead internal conductors. Since these first and second lead conductors are formed like a cross and linear shape respectively, the area intersecting the magnetic flux generated by the coil can minimized, and so eddy current within the first and second internal conductors can be prevented from generating.
Further, the chip is shaped like a rectangular solid and the insulating material sheets are shaped like a square, and further the first lead internal conductor is exposed to the four surfaces of the chip which are parallel to the winding center-line of the coil. Therefore, even when the external terminal electrode is formed on any face of the four surfaces, the same multi-laminated inductor may be obtained. Further, by forming a second lead internal conductor at varied position in the
Lowe Hauptman & Gilman & Berner LLP
Phan Thiem Dinh
Taiyo Yuden Co. Ltd.
LandOfFree
Method of manufacturing a multi-laminated 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 a multi-laminated inductor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing a multi-laminated inductor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3240308