JPH10241941A - Laminated chip inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of the electrical connection between each end section of a coil-like inner conductor and external electrodes by making the connecting areas larger by exposing each end section of the conductor at a plurality of spots on the peripheral side face of a ceramic laminated body and bringing the inner conductor in continuity with the external electrodes through the end sections. SOLUTION: A ceramic laminated body 42 is formed by successively laminating green sheets of a magnetic insulating ceramic, adhering the green sheets to each other with pressure, and sintering the stuck green sheets. At the time of forming the laminated body 42, lead-out conductors 44 and 45 are formed on the whole surfaces of the green sheets which become each end section of a coil-like inner conductor 43 constituting the laminated body 42. The conductors 44 and 45 are exposed on the whole peripheral side face of the laminated body 42. Then external electrodes 46 and 47 are formed on the end face and peripheral side face of the laminated body 42 near the end face to have a continuity with the lead-out conductors 44 and 45 of the inner conductor 43. Therefore, the reliability of the electrical connection between each end section of the coil-like inner conductor and the electrodes 46 and 47 can be improved by making the continuity areas larger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer chip inductor.

[0002]

2. Description of the Related Art A conventional multilayer chip inductor of this type is configured as shown in FIGS. 7 and 8, for example.
The arrow X indicates the direction in which the green sheets are stacked. As shown in FIG. 7, the multilayer chip inductor 1 includes a coil-shaped internal conductor 3 wound in a coil shape inside a ceramic laminate 2, and a lead conductor 4 that is an end of the coil-shaped internal conductor 3. External electrodes 6 and 7 are formed on the peripheral surface of the ceramic laminate 2 near the end face of the ceramic laminate 2 and the end face extending from the end face so as to be electrically connected to the ceramic laminate 2.

As shown in FIG. 8, a ceramic laminate 2 is made of magnetic ceramic green sheets 10, 10, 1 and 2.
0, 11 to 20, 21, 21, 21 are laminated in order from the bottom,
It is obtained by pressing and sintering.

The green sheets 10 and 21 are dummy green sheets on which no internal conductor is formed. Green sheets 11 to 20 are internal conductors 24 to 3 of less than one turn.
3 are formed on each surface. Further, via holes are provided in the green sheets 12 to 20 at one ends of the internal conductors 25 to 33. When the green sheets 11 to 20 are laminated, the internal conductors 24 to 33 are sequentially conducted through the via holes. The coil-shaped inner conductor 3 is formed. Internal conductors 24 and 33 formed on green sheets 11 and 20
At one end thereof are provided with lead conductors 4 and 5 of the coiled internal conductor 3 so as to be exposed on one side surface of the green sheets 11 and 20.

[0005] External electrodes 6 and 7 are formed on and near the end faces of the ceramic laminate 2 described above, and the external electrodes 6 and 7 are electrically connected to the lead conductors 4 and 5 of the coiled internal conductor 3, thereby providing a multilayer chip. An inductor 1 is obtained. In the multilayer chip inductor 1 having such a configuration, the ceramic multilayer body 2
The lead-out conductors 4 and 5 exposed on one surface of the peripheral side surface and the external electrodes 6 and 7 are electrically connected.

[0006]

However, the lead conductors 4 and 5 have a small thickness and are exposed only on one surface of the peripheral side surface of the ceramic laminate 2. Since the area is small, when the ceramic laminate 2 is fired, a part of the exposed portions of the lead conductors 4 and 5 is scattered, and the conduction between the coil-shaped internal conductor 3 and the external electrodes 6 and 7 is interrupted. There was a problem that reliability was low.

[0007] When the circuit board on which the multilayer chip inductor 1 is mounted is deformed, for example, bent, internal stress is generated in the multilayer chip inductor 1. When the internal stress acts in a direction to separate the conductive portions between the lead conductors 4 and 5 of the multilayer chip inductor 1 and the external electrodes 6 and 7, there is a problem that the conductive portions are disconnected.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems. The object of the present invention is to increase the conductive area of a conductive portion between a lead conductor of a coiled internal conductor and an external electrode, thereby improving the reliability of electrical connection. To provide a multilayer chip inductor having a high performance.

[0009]

In order to achieve the above object, in a multilayer chip inductor according to the present invention, a ceramic laminate, a coil-shaped internal conductor formed inside the ceramic laminate, and the ceramic An end face of the laminate and external electrodes extending from the end face and formed on the peripheral side surface of the ceramic laminate near the end face, wherein the coil-shaped internal conductor is provided at each end of the coil-shaped internal conductor. Are exposed on a plurality of side surfaces of the peripheral side surface, and are electrically connected to the external electrodes via the end portions.

[0010] The coil-shaped internal conductor is formed on a laminated surface of the ceramic laminate. Further, it is preferable that each end of the coil-shaped internal conductor is formed on a laminated surface of a plurality of layers of the ceramic laminate. Also,
The external electrode is formed on an end surface of the ceramic laminate that is substantially perpendicular to the laminating direction and on a peripheral side surface near the end surface.

Thus, even if the thickness of the coiled internal conductor is small, the area where each end of the coiled internal conductor is exposed on the peripheral side surface of the ceramic laminate can be increased, and each end of the coiled internal conductor can be exposed. And the conduction area between the electrode and the external electrode can be increased.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the present invention will be described in detail with reference to FIGS. 1, 2 and 3. FIG. However, as can be understood by comparing FIG. 2 and FIG. 8, the lead conductors 4 formed on the green sheets 48 and 49 can be understood.
Reference numerals 4 and 45 are different from the lead conductors 4 and 5, and the same parts as those in the above-described conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 1, the multilayer chip inductor 41 includes a coiled internal conductor 43 inside a ceramic laminate 42, and is electrically connected to lead conductors 44 and 45 which are ends of the coiled internal conductor 43. So that the external electrodes 46,
47 is formed on the peripheral surface of the ceramic laminate 42 near the end face extending from the end face and the end face of the ceramic laminate 42.

As shown in FIG. 2, the ceramic laminate 42 is made of an insulating ceramic green sheet 1 such as a magnetic material.
0, 10, 10, 48, 12 to 19, 49, 21, 2
It is obtained by laminating, pressing and sintering 1, 21 in order from the bottom.

The green sheets 48 and 49 are for the lead conductor 4.
4 and 45 are formed on the entire surface, and via holes are provided at predetermined positions in the green sheet 49 so as to be electrically connected to one end of the internal conductor 32 formed in the green sheet 19. When the green sheets 48, 12 to 19, and 49 are stacked, the lead conductors 44 and 45 become the respective ends of the coil-shaped internal conductor 43 formed by integrating the internal conductors 25 to 32. It is exposed on the entire peripheral side surface of the ceramic laminate 42.

External electrodes 46 and 47 are formed on the end face of the above-mentioned ceramic laminate 42 and the peripheral side face near the end face, and the external electrodes 46 and 47 are connected to the lead conductor 4 of the coil-shaped internal conductor 43.
By conducting to 4, 45, as shown in FIG.
The multilayer chip inductor 41 is obtained. In the multilayer chip inductor 41 having such a configuration, the lead conductors 44 and 45 and the external electrodes 46 and 47 are electrically connected to each other on the entire peripheral side surface of the ceramic multilayer body 42.

Another embodiment of the present invention will be described in detail with reference to FIGS. However, as can be understood from a comparison between FIG. 5 and FIG. 2, the number of green sheets 49 and 50 in which lead conductors are formed in place of the dummy green sheets 10 and 21 is increased. The same parts as those of the embodiment are denoted by the same reference numerals, and detailed description is omitted.

As shown in FIG. 4, the multilayer chip inductor 51 includes a coiled internal conductor 53 inside a ceramic laminate 52, and is electrically connected to a plurality of lead conductors 44 and 45 of the coiled internal conductor 53. , Ceramic laminate 52
External electrodes 56 and 57 are formed on the end face and near the end face.

As shown in FIG. 5, the ceramic laminate 52 includes ceramic green sheets 10, 48, 50,
0, 12 to 19, 49, 49, 49, and 21 are obtained by laminating, pressing, and sintering in order from the bottom.

The green sheet 50 has a lead-out conductor 44 formed on the entire surface, and a via hole is provided so as to be electrically connected to the lead-out conductor 44 formed on the green sheet 48. The lead conductors 44 and 45 are the green sheets 4
When the 8, 50, 50, 12 to 19, 49, 49, 49 are stacked, the internal conductors 25 to 32 become the respective ends of the coiled internal conductor 53 integrally formed, and are formed of ceramic. It is exposed on the entire peripheral side surface of the laminate 52 and in a plurality of layers.

External electrodes 56 and 57 are formed on the end face of the above-mentioned ceramic laminate 52 and the peripheral side face near the end face, and the external electrodes 56 and 57 are connected to the lead conductor 4 of the coil-shaped internal conductor 53.
By conducting the current to 4, 45, the multilayer chip inductor 51 is obtained.

The multilayer chip inductor 51 having such a configuration
The lead conductors 44 and 45 are exposed on all the peripheral side surfaces of the plurality of layers of the ceramic laminate 52, and the lead conductors 44 and 45 and the external electrodes 56 and 57 are composed of the plurality of layers of the ceramic laminate 52 and the entire peripheral side surface. To conduct.

The lead conductor formed on the green sheet is not limited to the above-mentioned embodiment, but is shown in FIG.
Leader conductors having various shapes as shown in (a) to (d) can be appropriately used.

The green sheet 71 shown in FIG.
A lead-out portion 72 electrically connected to the coil-shaped inner conductor on the surface thereof;
The lead conductor 73 is formed near the peripheral side surface so as to be exposed on the entire peripheral side surface of the green sheet 71.

The green sheet 74 shown in FIG.
A lead-out portion 75 that is electrically connected to the coil-shaped internal conductor on its surface;
A lead conductor 76 is formed in the vicinity of the peripheral surface so as to be exposed on substantially all of the four peripheral surfaces of the green sheet 74.

The green sheet 77 shown in FIG.
A lead portion 78 having a shape different from that of the green sheet 74 and a lead conductor 79 formed in the vicinity of the peripheral side surface so as to be exposed on almost all four peripheral side surfaces of the green sheet 77 are formed.

The green sheet 80 shown in FIG.
A lead-out portion 81 that is electrically connected to the coil-shaped internal conductor on its surface;
A lead conductor 82 is formed near the peripheral side surface so as to be exposed on two peripheral side surfaces of the green sheet 80.

[0028]

As described above, in the multilayer chip inductor according to the present invention, each of the lead-out conductors of the coil-shaped inner conductor is exposed at a plurality of locations on the peripheral side surface of the ceramic laminate and further over a plurality of layers. As a result, the conductive area is increased, and the reliability of the electrical connection between each end of the coiled internal conductor and the external electrode can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional view of a multilayer chip inductor according to an embodiment of the present invention.

FIG. 2 is a perspective view of the multilayer chip inductor of FIG. 1 before stacking.

FIG. 3 is a perspective view of the multilayer chip inductor of FIG. 1;

FIG. 4 is a sectional view of a multilayer chip inductor according to another embodiment of the present invention.

5 is a perspective view of the multilayer chip inductor of FIG. 4 before stacking.

FIG. 6 is a front view showing another modified example of the lead conductor.

FIG. 7 is a sectional view of a conventional multilayer chip inductor.

FIG. 8 is a perspective view of a conventional multilayer chip inductor before lamination.

[Explanation of symbols]

 41 multilayer chip inductor 42 ceramic laminate 43 coiled inner conductor 44, 45 lead conductor 46, 47 external electrode X lamination direction

Claims (4)

[Claims] 1. A ceramic laminate, a coil-shaped internal conductor formed inside the ceramic laminate, and an end face of the ceramic laminate and a peripheral side surface of the ceramic laminate extending from the end face and near the end face. An external electrode formed,
Wherein each end of the coiled internal conductor is exposed on a plurality of side surfaces of the peripheral side surface, and is electrically connected to the external electrode via the end. Characterized multilayer chip inductor. 2. The multilayer chip inductor according to claim 1, wherein the coil-shaped internal conductor is formed on a lamination surface of the ceramic laminate. 3. The multilayer chip inductor according to claim 1, wherein each end of the coil-shaped internal conductor is formed on a lamination surface of a plurality of layers of the ceramic laminate. 4. The lamination according to claim 1, wherein the external electrode is formed on an end face substantially orthogonal to a lamination direction of the ceramic laminate and on a peripheral side surface near the end face. Type chip inductor.