JP2000058326A - Chip inductor and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact chip inductor having a frequency filter function in which a coil and a capacitor are formed on the same substrate, and a method for manufacturing this chip inductors. SOLUTION: A capacitor, in which a pair of electrodes 16 and 24 are formed with a ferroelectric film 22 interposed, is formed on a substrate 12 such as an insulating ceramic. An insulating layer 28 such as a glass coat is laminated on an electrode 24 of a capacitor 25, and a conductive material film 30 made of copper or the like is formed, so that the insulating layer 28 and the substrate 12 are surrounded. Spiral grooves 32 are formed on the conductive material film 30, and coil patterns can be obtained. A pair of coil patterns are formed from both the end parts to the central part of the substrate 12 and are connected in parallel with the capacitor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip inductor having a frequency filter function by integrally forming a capacitor and a coil on a substrate, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a capacitor and a coil are provided as separate components on a circuit board, and when forming a frequency filter, the coil and the capacitor are appropriately arranged on the circuit board to form a filter circuit. .

This inductor has been formed by a winding method using a magnetic core and a conductive winding, or a non-winding method using a thick film printing technique or a thin film photo etching technique. As disclosed in Japanese Unexamined Patent Application Publication No. 10-116731 as one of the non-winding methods, a conductive film is provided on the entire surface of a substrate, and the conductive film is spirally grooved using a laser or the like to form a coil pattern. Have also been proposed.

[0004] On the other hand, there is a small chip type capacitor in which an upper electrode and a lower electrode are formed via an insulating layer.

[0005]

In the case of the above-mentioned prior art, if the inductor is formed by a winding method, the coil is large and thick, which hinders miniaturization of electronic equipment.
Also, it was difficult to obtain a low inductance value in a high frequency circuit. Therefore, in order to meet the demand for the low inductance value and the narrow tolerance of the inductance value, a chip inductor can be formed by a non-winding method, but in this case, the manufacturing process is complicated and the performance of the inductor is reduced. It is structurally and manufacturingly difficult to improve the inductance tolerance, the Q characteristic and the self-resonant frequency which affect the performance, and furthermore, a high technology is required for the production.

On the other hand, even in the case of a chip-shaped capacitor, it is difficult to reduce the size of the circuit board because it has a predetermined size and thickness, and inductors and capacitors are separately provided at predetermined positions on the circuit board. As a result, production efficiency is low, requiring a lot of labor and time,
There was a problem that the manufacturing cost was high.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a small chip inductor having a coil and a capacitor formed on the same substrate and having a frequency filter function, and a method of manufacturing the same. Aim.

[0008]

A chip inductor according to the present invention comprises a capacitor having a pair of electrodes formed on an insulating substrate with a ferroelectric film interposed therebetween, and the electrodes of the capacitor are coated with glass or the like. And a conductor film of copper or the like is formed so as to surround the insulation layer and the substrate, and a spiral groove is formed in the conductor film to provide a coil pattern. The above coil pattern is
A pair is provided from both ends of the substrate toward the center, and is connected in parallel with the capacitor. Further, one electrode of the capacitor is connected to an electrode on the back surface of the substrate through a through hole, a side conductor, or the like formed in the substrate.

Further, according to a method of manufacturing a chip inductor of the present invention, an electrode is provided on an insulating substrate, the other electrode is formed with a ferroelectric film interposed therebetween, and the other electrode is coated with a glass. A conductor film is formed by plating or the like so as to surround the insulating layer and the substrate, and a spiral groove is formed in the conductor film to provide a coil pattern. is there.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a chip inductor 10 according to one embodiment of the present invention, which has a through hole 14 penetrating the front and back surfaces at a substantially central portion of a rectangular ceramic substrate 12. Around the through hole 14, a front surface electrode 16 is provided on the front surface side of the ceramic substrate 12, and a back surface electrode 18 is provided on the back surface. This surface electrode 16
The back electrode 18 is electrically connected to the back electrode 18 via a conductor layer 20 provided in the through hole 14. The outer surface of the surface electrode 16 is covered with an insulating ferroelectric film 22, and a counter electrode 24 is formed on the ferroelectric film 22.
The capacitor 25 is constituted. On the other hand, an insulator 26 such as a resist is provided around the back electrode 18.

Here, the ceramic substrate 12 is made of alumina,
Made of ceramics such as forsterite and mullite,
Each of the electrodes 16, 18, and 24 is formed of a metal or an alloy formed by plating or vapor deposition, a conductive resin, or the like. At this time, nickel or a nickel alloy is desirable for the front surface electrode 16 and the back surface electrode 18 because of the adhesive force to the ceramic substrate 12.
P, Ni-B, Ni-Cu-P, Ni-Co-P, Ni
-Pd-P, Ni-Sn-P, Ni-Mn-P, Ni-
WP, Ni-Fe-P, Ni-Co-B, Ni-Fe
-B or the like is used. The film thickness is preferably 0.5 μm or more in order to secure a sufficient adhesive force.

The counter electrode 24 forms a capacitor 25 together with the surface electrode 16 and the ferroelectric film 22.
It is desirable that the conductive layer 20 be made of the same conductive material as the front surface electrode 16.
In this case, nickel or a nickel alloy is preferable from the viewpoint of adhesion to the ceramic substrate 12, or a conductive paint may be used.

Further, the ferroelectric film 22 is made of a crystal such as barium titanate, lead zirconate titanate (hereinafter abbreviated as PZT) or strontium titanate (hereinafter abbreviated as BTO).
Any material can be used as long as a desired charge can be stored between the counter electrode 24 and the surface electrode 16.

A pair of glass coats 28 are provided so as to cover the surface of the counter electrode 24 except for a predetermined width near the center line of the ceramic substrate 12 and the side surface of the ferroelectric film 22. The glass coat 28 is a coating formed by applying and firing a fine powder paste of glass.

Further, metal plating 30 is formed on the front surface of the glass coat 28 and on the side and back surfaces of the ceramic substrate 12 except for the back electrode 18 and the insulator 26 around the back electrode 18. Further, a single spiral groove 32 is formed in the metal plating 30 so that the glass coat 28 or the ceramic substrate 12 is exposed to the bottom of the groove. An overcoat 34 of resin or the like is applied to the surface of the metal plating 30 provided with the groove 32 so as to cover the groove 32,
Each end face of the metal plating 30 is exposed and end face electrodes 35 and 36 are exposed.
To form

The metal plating 30 is desirably a copper plating having a low specific resistance.
Since 2 is formed, the thickness is preferably about 10 μm to 50 μm, and is appropriately selected.

Next, the chip inductor 10 of this embodiment will be described.
The method for manufacturing the will be described below. The method of manufacturing the chip inductor 10 according to the present embodiment will be described with reference to FIGS.
As shown in (d), a through-hole 14 penetrating the front and back surfaces is formed substantially at the center of the rectangular ceramic substrate 12. Next, a plating material containing nickel or a nickel alloy is used on the inner surface of the through hole 14 and a predetermined portion on the front and back surfaces of the ceramic substrate 12, and a film having a thickness of about 0.5 μm to 3 μm is formed by a normal electroless plating method. Provide a thick plating film. Thereby, on the front and back surfaces of the ceramic substrate 12,
The front surface electrode 16 and the back surface electrode 18 connected via the conductor layer 20 in the through hole 14 are formed.

At this time, before forming a plating film by a normal electroless plating method, the ceramic substrate 12 may be subjected to the same pretreatment as that of the prior art. After performing the etching process, a sensitizing process and an activation process are performed, and then a nickel-based plating film is formed on these surfaces to a predetermined thickness.

In addition to the electroless plating, a conductive resin is applied to the inside of the through-holes 14 and the conductive resin is printed at predetermined positions on the front and back surfaces of the ceramic substrate 12. The electrode 16 and the back surface electrode 18 may be formed.

Next, an insulating material such as a resist is applied to the peripheral portion of the back electrode 18 to form an insulator 26. A ferroelectric film 22 made of barium titanate, PZT, or the like is formed by printing, coating, sputtering, or the like so as to cover the entire surface of the surface electrode 16.

At this time, the entire surface of the surface electrode 16 on which the ferroelectric film 22 is provided and the ceramic substrate 1 around the surface electrode 16
A ferroelectric film 22 such as PZT may be formed by a hydrothermal synthesis method by previously providing a titanium film made of a material containing titanium metal, titanium oxide, or a titanium alloy on the two surfaces.

Further, a counter electrode 24 is formed on the surface of the ferroelectric film 22 by using the same material and method as those of the electrodes 16 and 18 described above.
To form At this time, a material different from each of the electrodes 16 and 18 may be used as a material forming the counter electrode 24, and a forming method can be appropriately selected.

Next, as shown in FIG. 2B, the paste containing the glass fine powder is applied to the surface of the counter electrode 24 except for a predetermined width of the approximate center line of the ceramic substrate 12 and the ferroelectric film 2.
2 and the surface of the ceramic substrate 12 and baking to form a glass coat 28. Thereby, the capacitor 15
In a predetermined range.

Next, as shown in FIG. 2C, a cylindrical metal plating 30 is formed on the side and back surfaces of the ceramic substrate 12 including the entire surface of the glass coat 28 by a usual electroplating technique.
Are formed on both ends of the ceramic substrate 12. As the metal at this time, copper is suitable because good characteristics are obtained and a material having low specific resistance is preferable. The copper plating film is easily formed by performing electroplating under ordinary conditions using a known copper plating bath such as a copper sulfate bath, a copper cyanide bath, a copper pyrophosphate bath, and a copper fluoride bath. You. At this time, the film thickness of the metal plating 30 is 10 μm from the AC resistance value in the high frequency region and the processing in the plating process and the groove cutting process.
It is preferably about m to 50 μm.

The metal plating 30 formed as described above
Can be put to practical use only in the state of plating, but it may be heat-treated at a temperature of 150 ° C. or more for further strengthening the adhesive force and lowering the specific resistance. It becomes a film. By such heat treatment,
In the case of a copper plating film, the film is densified and the resistance is reduced, and the adhesion to the glass coat 28 and the ceramic substrate 12 is improved, and the adhesion is improved. However, at this time, if the temperature in the heat treatment becomes too high, nickel and copper diffuse and the functions of the electrodes 16, 18, and 24 decrease, and the adhesion to the ceramic substrate 12 decreases. Is preferably about 500 ° C., generally about 150 ° C. to 250 ° C. Also, the processing time is appropriately selected according to the temperature, but generally is preferably about 0.5 to 5 hours. In the heat treatment atmosphere, for example, not limited to the atmosphere or an inert atmosphere,
It may be under reduced pressure or under vacuum.

The metal plating 30 is formed on the entire surface of the glass coat 28 and the ceramic substrate 12 except for the back electrode 18 and the insulator 26 therearound, and on the surface of the counter electrode 24 and the ferroelectric film 22 between the glass coats 28. May be formed.

Next, as shown in FIG. 2D, a helical groove 32 is formed on each metal plating 30 by using a YAG laser or the like to form a groove. At this time, the depth of the groove 32 depends on the glass coat 28 under the metal plating 30 or the ceramic substrate 1.
2 is exposed from the bottom surface of the groove 32. By forming the spiral groove 32 in the metal plating 30, a coil having a predetermined inductance is formed.

Thereafter, in order to protect the groove 32, the groove 32
, A resin, glass, or the like is applied so as to cover the substrate, and an overcoat 34 is provided.

The chip inductor 10 of this embodiment is
A capacitor and a coil are provided on the same ceramic substrate 12 and have a frequency filter function. Further, by using the back surface electrode 18 and the end surface electrodes 35 and 36 as connection terminals, the device can be used as a three-terminal device as shown in FIG. Although the device is a three-terminal device using the back electrode 18, surface mounting is also easily possible.

The present invention is not limited to the above embodiment. The ferroelectric film may be made of a material suitable for the capacitance of the capacitor, and the thickness and the area may be appropriately selected. Alternatively, a plurality of through holes may be provided and provided at positions corresponding to the circuit pattern on which the back electrode is provided. Further, without providing a through hole, a conductor portion may be formed on the side surface of the substrate to form a back surface electrode. Further, the end face electrode may be appropriately plated with solder or the like, whereby the surface mounting strength can be increased. Further, the capacitor may be a multilayer, and may also serve as a substrate and a capacitor.

[0031]

According to the chip inductor of the present invention, a coil and a capacitor are formed on the same chip substrate, and one chip substrate has a frequency filter function. In connection to the circuit board, the back electrode and the two end electrodes can be connection terminals. And a manufacturing process is simplified, a manufacturing cost is low, and a high quality and multifunctional chip electronic component can be provided. Further, since this chip inductor is thin, it is possible to make electronic equipment thinner and smaller.

[Brief description of the drawings]

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

FIGS. 2A and 2B are cross-sectional views showing manufacturing steps of a chip inductor according to an embodiment of the present invention, and FIGS.
(D).

FIG. 3 is a circuit diagram showing a chip inductor according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Chip inductor 12 Ceramic substrate 14 Through-hole 16 Front electrode 18 Back electrode 20 Conductor layer 22 Ferroelectric film 24 Counter electrode 25 Capacitor 26 Insulator 28 Glass coat 30 Metal plating 32 Groove 34 Overcoat 35, 36 End electrode

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yozo Ohara 3158 Shimo-Okubo, Osawano-machi, Kamishinkawa-gun, Toyama F-term (reference) 5E062 FF01 FF02 5E070 AA01 AA05 AB01 AB02 CC03 CC10 DB08 5E082 AA01 AB03 BB01 BC39 DD08 EE04 EE05 EE23 EE37 EE39 FF05 FG26 FG42 FG46 HH43 JJ23 KK01 LL15 MM05 MM24

Claims (4)

[Claims] A capacitor having a pair of electrodes formed on an insulating substrate with a ferroelectric film interposed therebetween, an insulating layer laminated on the electrodes of the capacitor, and surrounding the insulating layer and the substrate. A chip inductor in which a conductor film is formed as described above, and a spiral groove is formed in the conductor film to provide a coil pattern. 2. The chip inductor according to claim 1, wherein a pair of said coil patterns are provided from both ends of said substrate toward a central portion thereof, and are connected in parallel with said capacitor. 3. The chip inductor according to claim 1, wherein one electrode of the capacitor is connected to an electrode on the back surface of the substrate by a through hole or a side conductor formed in the substrate. 4. An electrode is provided on an insulating substrate, the other electrode is formed with a ferroelectric film interposed therebetween, and a heat-resistant insulating layer is laminated on the other electrode. A method for manufacturing a chip inductor, wherein a conductor film is formed so as to surround a layer and the substrate, and a spiral groove is formed in the conductor film to provide a coil pattern.