Patent Application
20130147593
The technical field relates to electronic components and methods for producing the electronic components, and more particularly, to an electronic component including a coil and outer electrodes and a method for producing the electronic component.
A multilayer inductor described in Japanese Unexamined Patent Application Publication No. 9-129447 (hereinafter referred to as Patent Document 1), for example, is known as an electronic component of the related art.
As illustrated in
As illustrated in
The outer electrodes 509a and 509b are provided on surfaces (hereinafter referred to as end surfaces) located at both ends of the multilayer body 503 in the stacking direction. The outer electrode 509a is connected to the end portion 507a by a connecting conductor 511a, and the outer electrode 509b is connected to the end portion 507b by a connecting conductor 511b. Each of the connecting conductors 511a and 511b is formed by connecting a plurality of via-hole conductors.
As illustrated in
In the above-described multilayer inductor 500, since the central axis of the coil 507 is parallel to the mounting plane X1, the direction of magnetic flux generated by the coil 507 is also parallel to the mounting plane X1. Therefore, even when the multilayer inductor 500 is mounted on the printed wiring board 515, reduction in self-inductance and Q-factor can be suppressed.
The present disclosure provides an electronic component having a connecting conductor configuration that can increase connection reliability between a coil and an outer electrode of the electronic component.
An electronic component according to an aspect of the disclosure includes a multilayer body having first and second outermost surfaces and including a plurality of insulator layers that are stacked together and having first and second surfaces that oppose each other in a stacking direction and side surfaces that connect the first and second surfaces to each other. The multilayer body includes a coil, a first connecting conductor provided on the first outermost surface of the multilayer body and not in contact with the side surfaces of the multilayer body, a first outer electrode provided on the first outermost surface of the multilayer body and covering the first connecting conductor, and a first via-hole conductor connecting one end portion of the coil and the first connecting conductor to each other and extending through at least one of the insulator layers in the stacking direction.
A method for producing the above electronic component according to another aspect of the present disclosure includes preparing the insulator layers, forming the first via-hole conductor and a second via-hole conductor in the insulator layers, forming coil conductors and the first connecting conductor on the insulator layers. The method includes stacking the insulator layers in or on which the first via-hole conductor, the second via-hole conductor, the coil conductors, and the first connecting conductor are formed to form the multilayer body, and forming the first outer electrode on the multilayer body.
The inventor realized the following with respect to the multilayer inductor 500 described above in Patent Document 1. The end portion 507a and the outer electrode 509a are connected to each other by the connecting conductor 511a. Therefore, the coil 507 and the outer electrode 509a are connected to each other only by the connecting conductor 511a, which is exposed at an end surface of the multilayer body 503. Since the contact area between the connecting conductor 511a and the outer electrode 509a is small, in the multilayer inductor 500, reliability of electrical connection between the coil 507 and the outer electrode 509a is not sufficient.
An electronic component according to an exemplary embodiment that can address the above shortcomings will be described with reference to the drawings.
The structure of an electronic component according to an exemplary embodiment will now be described with reference to
In the following description, the stacking direction of the multilayer body 12 of the electronic component 1 illustrated in
Referring to
The multilayer body 12 has a rectangular parallelepiped shape, and has a coil L incorporated therein. As illustrated in
The coil L is incorporated in the multilayer body 12. As illustrated in
As illustrated in
In the following description, in plan view viewed from the positive side in the z-axis direction, an upstream end of each coil conductor 18 in the counterclockwise direction is defined as an upstream end, and a downstream end of each coil conductor 18 in the counterclockwise direction is defined as a downstream end. The number of turns of each coil conductor 18 is not limited to ½. The number of turns of each coil conductor 18 can instead be a different value, for example, ¾ or ⅞. The upstream end of the coil conductor 18a (that is, the upstream end of the coil L) is the end portion A1, and the downstream end of the coil conductor 18e (that is, the downstream end of the coil L) is the end portion A2.
The via-hole conductor v5 extends through the insulator layer 16e in the z-axis direction, and is connected to the downstream end of the coil conductor 18a and the upstream end of the coil conductor 18b. The via-hole conductor v6 extends through the insulator layer 16f in the z-axis direction, and is connected to the downstream end of the coil conductor 18b and the upstream end of the coil conductor 18c. The via-hole conductor v7 extends through the insulator layer 16g in the z-axis direction, and is connected to the downstream end of the coil conductor 18c and the upstream end of the coil conductor 18d. The via-hole conductor v8 extends through the insulator layer 16h in the z-axis direction, and is connected to the downstream end of the coil conductor 18d and the upstream end of the coil conductor 18e.
The connecting conductor 22a is provided on the top surface S1, or first outermost surface of the multilayer body 12 (i.e., front surface of the insulator layer 16a) so as not to be in contact with the side surfaces S3 to S6 of the multilayer body 12 (i.e., outer edges of the insulator layer 16a). The shape of the connecting conductor 22a may be the same as the shape of any of the coil conductors 18a to 18e. In the present embodiment, the shape of the connecting conductor 22a is the same as the shape of the coil conductors 18b and 18d.
The connecting conductor 22b is provided on the bottom surface S2, or second outermost surface of the multilayer body 12 (i.e., back surface of the insulator layer 16m) so as not to be in contact with the side surfaces S3 to S6 of the multilayer body 12 (i.e., outer edges of the insulator layer 16m). The shape of the connecting conductor 22b may be the same as the shape of any of the coil conductors 18a to 18e. In the present embodiment, the shape of the connecting conductor 22b is the same as the shape of the coil conductors 18b and 18d.
As illustrated in
The via-hole conductors v1 to v4 extend through the insulator layers 16a to 16d, respectively, in the z-axis direction and are connected to each other, thereby forming a single via-hole conductor. An end portion of the via-hole conductor v1 on the positive side in z-axis direction is connected to the connecting conductor 22a, as illustrated in
As illustrated in
An exemplary method for producing the electronic component 1 having the above-described structure will now be described with reference to
First, ceramic green sheets to be formed into the insulator layers 16 are prepared. Specifically, ferric oxide (Fe2O3), zinc oxide (ZnO), nickel oxide (NiO), and copper oxide (CuO) in a certain weight ratio are prepared as raw materials and subjected to wet mixing in a ball mill. The thus-obtained mixture is dried and ground into powder, which is then calcined at 800° C. for one hour. The calcined powder is subjected to wet grinding in a ball mill, dried, and then disintegrated to obtain ferrite ceramic powder.
The ferrite ceramic powder is mixed with a binder (e.g., vinyl acetate or water-soluble acrylic) a plasticizer, a humectant, and a dispersant in a ball mill. Then, defoaming is performed by reducing pressure. Subsequently, the defoamed mixture is formed into the shape of a sheet on a carrier sheet and dried by a doctor blade method. Thus, each of the ceramic green sheets is produced. The thickness of the ceramic green sheets can be, for example, 10 to 15 μm.
Next, the via-hole conductors v1 to v13 are formed in the ceramic green sheets to be formed into the insulator layers 16a to 16m, respectively. Specifically, via holes are formed in the ceramic green sheets to be formed into the insulator layers 16a to 16m by irradiating the ceramic green sheets with a laser beam. Subsequently, the via holes are filled with a paste made of a conductive material such as Ag, Pd, Cu, Au, or an alloy thereof by, for example, a printing method. Thus, the via-hole conductors v1 to v13 are formed.
Next, the coil conductors 18a to 18e are formed on the ceramic green sheets to be formed into the insulator layers 16e to 16i, respectively, by applying a paste made of a conductive material to the ceramic green sheets by, for example, screen printing or photolithography. The paste made of a conductive material is obtained by, for example, adding a varnish and a solvent to Ag.
The connecting conductor 22a is formed on the front surface of the ceramic green sheet to be formed into the insulator layer 16a by applying a paste made of a conductive material to the front surface of the ceramic green sheet by, for example, screen printing or photolithography. The paste made of a conductive material is obtained by, for example, adding a varnish and a solvent to Ag. The connecting conductor 22a does not cross any of the cut lines used to separate the multilayer bodies 12 from each other. The connecting conductor 22a is formed in the same shape as the shape of any of the coil conductors 18a to 18e.
The process of forming the coil conductors 18 (i.e., coil conductors 18a to 18e) and the connecting conductor 22a and the process of filling the via holes with a paste made of a conductive material (Ag or Ag—Pt) may be performed in the same step.
Next, the ceramic green sheets to be formed into the insulator layers 16a to 16m are stacked and pressure-bonded together so as to be arranged in that order from the positive side to the negative side in the z-axis direction. Thus, a green mother multilayer body is formed. Specifically, the ceramic green sheets are stacked and temporarily pressure-bonded one at a time. Subsequently, the mother multilayer body is subjected to permanent pressure bonding by isostatic pressing. The isostatic pressing is performed at a pressure of 100 MPa and a temperature of 45° C.
Subsequently, the connecting conductor 22b is formed on the back surface of the ceramic green sheet to be formed into the insulator layer 16m by printing or transferring. The connecting conductor 22b does not cross any of the cut lines used to separate the multilayer bodies 12 from each other. The connecting conductor 22b is formed in the same shape as the shape of any of the coil conductors 18a to 18e.
Next, the green mother multilayer body is cut so as to separate the green multilayer bodies 12 from each other. Specifically, the green mother multilayer body is cut with a dicer or the like.
Next, the surfaces the multilayer bodies 12 are subjected to chamfering by barrel polishing. After that, the green multilayer bodies 12 are subjected to debinding and firing processes. The debinding process is performed in, for example, a low oxygen atmosphere at about 500° C. for two hours. The firing process is performed, for example, at 870° C. to 900° C. for 2.5 hours.
Next, an electrode paste made of a conductive material that contains, for example, Ag as a main component is applied to the top surface S1, the bottom surface S2, and parts of the side surfaces S3 to S6 of each multilayer body 12. The applied electrode paste is baked at about 800° C. for one hour. Thus, a silver electrode to be included in the outer electrode 14 is formed. The outer electrode 14 is formed by performing Ni—Sn plating on the surface of the silver electrode. The electronic component 1 is completed through the above-described steps.
According to the electronic component 1, connection reliability between the coil L and the outer electrode 14a can be increased as described below. The electronic component 1 differs from the multilayer inductor 500 of Patent Document 1 in that the connecting conductor 22a is provided on the top surface S1 of the multilayer body, as illustrated in
In the multilayer inductor 500, the outer electrode 509a is formed after the multilayer body 503 is subjected to firing and barrel polishing. In other words, the outer electrode 509a and the connecting conductor 511a are formed in different steps. Therefore, there is a risk that the outer electrode 509a cannot be sufficiently connected to the connecting conductor 511a when the outer electrode 509a is formed. As a result, disconnection between the outer electrode 509a and the connecting conductor 511a easily occurs. In particular, the connecting conductor 511a and the outer electrode 509a are connected to each other in an area in which the connecting conductor 511a is exposed at an end surface of the multilayer body 503. Therefore, the connecting area is relatively small. As a result, disconnection between the outer electrode 509a and the connecting conductor 511a particularly easily occurs.
In contrast, the connecting conductor 22a is formed immediately after the via-hole conductor v1 is formed or together with the via-hole conductor v1. Therefore, the possibility of disconnection between the connecting conductor 22a and the via-hole conductor v1 is lower than that of disconnection between the outer electrode 509a and the connecting conductor 511a. In addition, in the electronic component 1, the outer electrode 14a is connected to the connecting conductor 22a. Since the connecting conductor 22a is a conductive layer, the contact area between the connecting conductor 22a and the outer electrode 14a is relatively large. Therefore, the possibility of disconnection between the outer electrode 14a and the connecting conductor 22a is extremely low. Accordingly, disconnection between the coil L and the outer electrode 14a is less likely to occur in the electronic component 1 than in the multilayer inductor 500. In other words, connection reliability between the coil L and the outer electrode 14a of the electronic component 1 can be increased. For a similar reason, connection reliability between the coil L and the outer electrode 14b of the electronic component 1 can also be increased.
As illustrated in
As illustrated in
Since the coil conductors 18 and the connecting conductors 22a and 22b are not in contact with the side surfaces S3 to S6, the occurrence of defects such as delamination and cracks between the insulator layers 16 can be reduced.
The electronic component 1 having the above-described structure is not limited to the above exemplary embodiment, and can be modified within the scope thereof.
As in the electronic component 1 illustrated in
The electronic component 1 may instead be structured such that neither the wiring conductor 30 nor the connecting conductor 22b is provided on the insulator layer 16m.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-183094 | Aug 2010 | JP | national |
The present application is a continuation of International Application No. PCT/JP2011/061326, filed May 17, 2011, which claims priority claims priority to Japanese Patent Application No. 2010-183094 filed on Aug. 18, 2010, the entire contents of each of these applications being incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2011/061326 | May 2011 | US |
| Child | 13766498 | US |
