JP5282653B2 - Multilayer electronic component and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the formation step for a nickel plating film though, in a laminated electronic part having an external terminal electrode that is substantially formed by using plating, a copper plating film is formed as a base of the external terminal electrode and a nickel plating film is necessary to be formed as a barrier layer thereon. <P>SOLUTION: Nickel is used as an electric conduction component for inner electrodes 3 and 4, and copper plating films 10 and 11 are formed on the exposed surfaces of the inner electrodes 3 and 4 in a part 2. Then, the part is heated at 600&deg;C or higher to segregate an oxide of the nickel on the surface of the copper plating films 10 and 11. The segregated oxide of the nickel is reduced to form metal films 12 and 13 made of nickel along the surfaces of the copper plating films 10 and 11. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a multilayer electronic component and a method for manufacturing the same, and in particular, a multilayer electronic component formed by direct plating so that an external terminal electrode is electrically connected to a plurality of internal conductors and a method for manufacturing the same. It is about.

  In recent years, the market for small portable electronic devices such as mobile phones, notebook computers, digital cameras, and digital audio devices is expanding. In these portable electronic devices, while miniaturization is progressing, high performance is also progressing at the same time. Many types of multilayer electronic components such as multilayer ceramic electronic components are mounted on portable electronic devices. However, there is a demand for miniaturization and high performance of multilayer electronic components. For example, in a multilayer ceramic capacitor, downsizing and large capacity are required.

  As a means for reducing the size and increasing the capacity of the multilayer ceramic capacitor, it is effective to widen the effective area of the internal electrode in addition to thinning the dielectric ceramic layer. However, when mass-producing multilayer ceramic capacitors, it is necessary to secure a certain amount of side margin between the internal electrode and the side surface of the ceramic body and end margin between the internal electrode and the end surface of the ceramic body. There are restrictions on expanding the range.

  In order to increase the effective area of the internal electrode while ensuring a predetermined margin, it is necessary to increase the area of the dielectric ceramic layer. However, there is a limit to increasing the area of the dielectric ceramic layer within the determined dimensional standard, and the thickness of the external terminal electrode is hindered.

  Conventionally, the external terminal electrode of a multilayer ceramic capacitor has typically been formed by applying a conductive paste to the end of a ceramic body and baking it. As a method for applying the conductive paste, the main part is to immerse and pull up the end of the ceramic body in a paste tank. However, in this method, the viscosity of the conductive paste affects the central part of the end face of the ceramic body. The conductive paste is thick and easy to adhere to. For this reason, the area of the dielectric ceramic layer has to be reduced as the external terminal electrode is partially thickened.

  In response to this, a method of directly forming the external terminal electrode by plating has been proposed (for example, see Patent Document 1). In this method, a plating film is deposited with the exposed portion of the internal electrode on the end face of the ceramic body as a nucleus, and this plating film grows, that is, the exposed portion of the adjacent internal electrode is connected to each other by the surrounding of the plating film. Is done. According to this method, it is possible to form a thin and flat electrode film as compared with the conventional method using a conductive paste.

  As described above, when the external terminal electrode is directly formed by plating, it is preferable to use copper as the metal constituting the plating film in consideration of throwing power.

  On the other hand, when mounting a multilayer ceramic capacitor using solder, a nickel plating film as a barrier layer is formed on the copper plating film, and tin or gold as a main component for ensuring solder wettability is formed. Therefore, the external terminal electrode is composed of a total of three or more plating films, and as a result, the thickness is increased.

  If the first layer is composed of a nickel plating film instead of the copper plating film, a total of two layers are sufficient, but the following problems are caused.

  Nickel is inferior in throwing power and inferior in adhesion compared to copper. In addition, nickel is often used as the conductive component of the internal electrode of the multilayer ceramic capacitor. In this case, even if heat treatment is performed, the metal constituting the plating film on the external terminal electrode side and the conductive component of the internal electrode are the same element. There is almost no diffusion phenomenon. Therefore, the sealing property at the interface between the external terminal electrode and the internal electrode is inferior, and entry of moisture or the like is allowed.

International Publication No. 2007/049456 Pamphlet

  Therefore, an object of the present invention is to provide a multilayer electronic component and a method for manufacturing the same, which can solve the above-described problems.

  The present invention includes a step of preparing a component body having a laminated structure in which a plurality of internal electrodes including a first metal as a conductive component are formed therein, and each part of the internal electrodes is exposed, In order to solve the technical problem described above, first directed to a method for manufacturing a multilayer electronic component, comprising a step of forming an external terminal electrode to be electrically connected on an outer surface of a component main body. It is characterized by having the following configuration.

That is, the step of forming the external terminal electrode includes a step of forming a plating film by plating a second metal different from the first metal on the exposed surface of the internal electrode in the component main body, and a plating film. By heat-treating the component main body formed with a temperature of 600 ° C. or higher, the step of segregating the first metal oxide on the surface of the plating film and reducing the segregated first metal oxide And a step of forming a metal layer made of the first metal along the surface of the plating film, wherein the main component of the first metal is nickel and the main component of the second metal is copper. It is said .

The method of manufacturing a multilayer electronic component according to the present invention, the step of heat treatment, it is preferable that the temperature of 1000 to 1100 ° C., and the oxygen concentration of 100~200ppm applied.

  The present invention also provides a component body having a laminated structure in which a plurality of internal electrodes including a first metal as a conductive component are formed therein, and a part of each internal electrode is exposed, and the internal electrode and the electrical And an external terminal electrode formed on the outer surface of the component main body.

In the multilayer electronic component according to the present invention, the external terminal electrode is formed by plating directly on the exposed surface of the internal electrode in the component main body, and a plating film made of a second metal different from the first metal, and plating And a metal layer made of a first metal segregated along the surface of the film, wherein the main component of the first metal is nickel and the main component of the second metal is copper .

According to this invention, the metal layer made of the first metal that becomes the conductive component of the internal electrode can be formed along the surface of the plating film made of the second metal that becomes the first layer of the external terminal electrode. . Therefore, the external terminal electrodes, for example, copper plating film, a nickel plated film thereon, and if you want to configure tin or gold-plated film thereon, so nickel is used as the conductive component of the internal electrode, an intermediate nickel plating film The process for forming can be omitted, and the thickness of the external terminal electrode as a whole can be reduced.

The main component of the first metal is nickel, the main component of the second metal is copper, if Hodokose heat treatment by applying an oxygen concentration of temperatures, and 100~200ppm of 1000 to 1100 ° C., the internal electrodes As a conductive component, nickel is effectively segregated on the surface of the copper plating film constituting the external terminal electrode, and mutual diffusion can be effectively generated between the copper plating film and the internal electrode. .

It is sectional drawing which shows the multilayer electronic component manufactured by the manufacturing method by one Embodiment of this invention. FIG. 2 is a cross-sectional view showing a state after a plating film is formed on a component main body in order to form an external terminal electrode in the course of the manufacturing process of the multilayer electronic component shown in FIG. 1. FIG. 2 is a cross-sectional view illustrating a state after a heat treatment is performed on a component main body on which the plating film is formed in order to form an external terminal electrode during the manufacturing process of the multilayer electronic component illustrated in FIG. 1.

  With reference to FIG. 1, the structure of the multilayer electronic component 1 manufactured by the manufacturing method according to the embodiment of the present invention will be described.

  The multilayer electronic component 1 includes a component body 2 having a multilayer structure. The component body 2 has a plurality of internal electrodes 3 and 4 formed therein. More specifically, the component main body 2 includes a plurality of laminated insulator layers 5 and a plurality of layered internal electrodes 3 and 4 formed along an interface between the insulator layers 5.

  When the multilayer electronic component 1 constitutes a multilayer ceramic capacitor, the insulator layer 5 is composed of a dielectric ceramic. In addition, the multilayer electronic component 1 may constitute an inductor, a thermistor, a piezoelectric component, or the like. Therefore, depending on the function of the multilayer electronic component 1, the insulator layer 5 may be composed of a dielectric ceramic, a magnetic ceramic, a semiconductor ceramic, a piezoelectric ceramic, or the like, or a material containing a resin. It may be configured.

  The ends of the plurality of internal electrodes 3 and the plurality of internal electrodes 4 are exposed at one and the other end surfaces 6 and 7 of the component body 2, respectively. External terminal electrodes 8 and 9 are formed so that each end is electrically connected to each other.

  The illustrated multilayer electronic component 1 is a two-terminal type including two external terminal electrodes 8 and 9, but the present invention can also be applied to a multi-terminal multilayer electronic component.

  Each of external terminal electrodes 8 and 9 includes plating films 10 and 11 formed by direct plating on exposed surfaces of internal electrodes 3 and 4 in component body 2, that is, end faces 6 and 7, and surfaces of plating films 10 and 11. And metal layers 12 and 13 segregated along the line.

  The metal constituting the conductive component of the internal electrodes 3 and 4, the metal constituting the plating films 10 and 11, and the metal constituting the metal layers 12 and 13 are selected as follows. That is, when the metal serving as the conductive component of the internal electrodes 3 and 4 is the first metal, the metal constituting the plating films 10 and 11 is a second metal different from the first metal, and the metal layer 12 And the metal which comprises 13 is made into the 1st metal.

More specifically, the main component of the first metal described above is nickel, and the main component of the second metal is copper. By using copper as the main component of the plating films 10 and 11, the throwing power of the plating films 10 and 11 can be improved, and a sufficient fixing force can be obtained in the plating films 10 and 11. Further, by using nickel as the main component of the metal layers 12 and 13, the metal layers 12 and 13 can function as a barrier layer during mounting using solder.

  Although not shown in FIG. 1, the external terminal electrodes 8 and 9 made of the plating films 10 and 11 and the metal layers 12 and 13 are further plated with tin or gold, which is good for the external terminal electrodes 8 and 9. It is preferable that good solder wettability is provided.

  Next, a method for manufacturing the multilayer electronic component 1 shown in FIG. 1, particularly a method for forming the external terminal electrodes 8 and 9 will be described.

  First, the component main body 2 is produced by a known method. Next, the external terminal electrodes 8 and 9 are formed on the end faces 6 and 7 of the component body 2 so as to be electrically connected to the internal electrodes 3 and 4.

  In forming the external terminal electrodes 8 and 9, first, plating films 10 and 11 are formed on the end faces 6 and 7 of the component body 2 as shown in FIG. 2. The plating for forming the plating films 10 and 11 may be either electrolytic plating or electroless plating.

  Next, the component body 2 on which the plating films 10 and 11 are formed as described above is heat-treated at a temperature of 600 ° C. or higher. As a result, the oxide of the first metal as the conductive component of the internal electrodes 3 and 4 is segregated on the surfaces of the plating films 10 and 11, and as shown in FIG. 3, the segregation made of the oxide of the first metal. Layers 14 and 15 are formed.

As described above, the major component of the first metal is nickel, the main component of the second metal constituting the plating film 10 and 11 is a copper, in the above heat treatment step, the temperature of 1000 to 1100 ° C. And conditions such as 100-200 ppm oxygen concentration are preferably applied. When such conditions are applied, nickel contained in the internal electrodes 3 and 4 is effectively segregated on the surfaces of the plating films 10 and 11 mainly composed of copper, and the plating films 10 and 11 and the internal electrodes 3 and This is because interdiffusion can effectively occur between the four.

Next, the oxide of the first metal constituting the segregation layers 14 and 15 is reduced. As a result, as shown in FIG. 1, metal layers 12 and 13 made of the first metal are formed along the surfaces of the plating films 10 and 11. This reduction treatment is preferably performed, for example, at a temperature of 300 to 450 ° C. for about 1 to 60 minutes in a reducing atmosphere containing hydrogen (for example, a mixed atmosphere of N ₂ and H ₂ ).

  Next, experimental examples carried out to confirm the effects of the present invention will be described.

  First, as a component body, the length is 1.9 mm, the width is 1.05 mm, and the height is 1.05 mm. The insulator layer is made of a barium titanate dielectric ceramic, and the main component of the conductive component of the internal electrode is nickel. The number of stacked internal electrodes was 416, and the thickness of the insulator layer was 1.9 μm.

Next, electrolytic plating was applied to the component main body to form a copper plating film having a thickness of 7 μm serving as a base for the external terminal electrode electrically connected to the internal electrode. Here, as the plating bath, “Pyrobrite Process” manufactured by Uemura Kogyo Co., Ltd. was used, and the bath temperature was adjusted to 55 ° C. and the pH was adjusted to 8.8. In the plating process, a horizontal rotating barrel having a barrel volume of 300 ml was used, the barrel rotation speed was set to 12 rpm, and a conductive medium having a diameter of 1.8 mm was used for 60 minutes at a current density of 0.30 A / dm ² .

  Next, the component main body on which the copper plating film was formed as described above was heat-treated under the heat treatment conditions shown in Table 1 with the temperature and oxygen concentration.

Next, the component main body was reduced. This reduction treatment was performed at a temperature of 400 ° C. for 10 minutes in a mixed atmosphere of N ₂ and H ₂ .

Next, a tin plating process was performed to form a 4 μm thick tin plating film that forms the surface layer of the external terminal electrode. In this tin plating, “Sn-235” manufactured by Dipsol was used as a plating bath, the bath temperature was 30 ° C., and the pH was adjusted to 5.0. Further, a horizontal rotating barrel having a barrel volume of 300 ml was used, the barrel rotation speed was set to 12 rpm, and a conductive medium having a diameter of 1.8 mm was used for 60 minutes at a current density of 0.10 A / dm ² .

  The multilayer electronic component according to each sample thus obtained was embedded in resin and polished to expose the cross section. Then, FIB processing was performed at an angle of 5 degrees with respect to the exposed surface, and the copper / nickel diffusion state of the processed cross section was subjected to mapping analysis by EDX. For the analysis of the diffusion state, the diffusion behavior of the nickel component was particularly focused. The result is shown in the column of “copper / nickel diffusion state” in Table 1.

  As can be seen from Table 1, according to Samples 1 and 2 that satisfy both the conditions of a temperature of 1000 to 1100 ° C. and an oxygen concentration of 100 to 200 ppm as heat treatment conditions, a nickel component is present in the vicinity of the surface of the copper plating film. The metal layer made of nickel could be formed along the surface of the copper plating film by performing the reduction treatment.

  On the other hand, in Samples 3 to 5, the nickel component is uniformly diffused in the copper plating film, and even if reduction treatment is performed, a metal layer made of nickel can be sufficiently formed along the surface of the copper plating film. There wasn't.

DESCRIPTION OF SYMBOLS 1 Laminated type electronic component 2 Component main body 3, 4 Internal electrode 8, 9 External terminal electrode 10, 11 Plating film 12, 13 Metal layer 14, 15 Segregation layer

Claims (3)

A step of preparing a component body having a laminated structure in which a plurality of internal electrodes including a first metal as a conductive component are formed therein, and each part of the internal electrodes is exposed;
Forming an external terminal electrode electrically connected to the internal electrode on the outer surface of the component body,
The step of forming the external terminal electrode includes:
Forming a plating film on the exposed surface of the internal electrode in the component body by plating a second metal different from the first metal;
A step of segregating the oxide of the first metal on the surface of the plating film by heat-treating the component main body on which the plating film is formed at a temperature of 600 ° C. or higher;
Forming a metal layer made of the first metal along the surface of the plating film by reducing the segregated oxide of the first metal ,
The manufacturing method of a multilayer electronic component , wherein the main component of the first metal is nickel and the main component of the second metal is copper . The method for manufacturing a multilayer electronic component according to claim 1 , wherein a temperature of 1000 to 1100 ° C. and an oxygen concentration of 100 to 200 ppm are applied in the heat treatment step. A plurality of internal electrodes including a first metal as a conductive component are formed therein, and each of the internal electrodes is exposed, a component body having a laminated structure,
An external terminal electrode electrically connected to the internal electrode and formed on the outer surface of the component body;
The external terminal electrode is formed by direct plating on the exposed surface of the internal electrode in the component main body, and is formed of a second metal different from the first metal, along the surface of the plating film. and a metal layer made of the first metal segregated Te,
A multilayer electronic component , wherein the main component of the first metal is nickel and the main component of the second metal is copper .

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