JP2010027730A - Ceramic multilayer electronic component and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic multilayer electronic component and its manufacturing method capable of maintaining a good electrical connection between an internal electrode and a base electrode while protecting the surface of an element assembly with a glass layer. <P>SOLUTION: A ceramic multilayer electronic component 1 related to this embodiment includes: an element assembly 2 principally composed of ceramics, internal electrodes 3 arranged inside the element assembly 2 that project from the end surface of the element assembly 2, first base electrodes 5 formed on the end surface of the element assembly 2, glass layers 6 that cover the first base electrodes 5 and the front surface of the element assembly 2, and second base electrodes 7 formed on the glass layers 6 located on the position comparable to the end surface of the element assembly 2. The internal electrodes 3 penetrate the first base electrodes 5 and the glass layers 6, and reach the second base electrodes 7. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multilayer ceramic electronic component having a multilayer structure of an element body made of ceramics and internal electrodes, and a method for manufacturing the same.

  2. Description of the Related Art In recent years, in a ceramic multilayer electronic component made of a thermistor, a capacitor, an inductor, a LTCC (Low Temperature Co-fired Ceramics), a varistor, or a composite thereof, an internal electrode is formed inside a ceramic body. The internal electrode is exposed on the end face of the element body, and after forming a base electrode connected to the internal electrode on the end face of the element body, a terminal electrode made of, for example, a Ni layer and an Sn layer is formed on the base electrode by plating. Has been.

  In the plating of the Ni layer and the Sn layer, a technique for applying a coating such as glass on the surface of the element body has been proposed in order to prevent the erosion of the element body made of ceramics and the deposition of the plating metal on the surface of the element body. (See Patent Document 1). In Patent Document 1, an electrode (base electrode) made of Ag is formed on glass corresponding to an end face of an element body after the surface of the element body is coated with glass. On the electrode made of Ag, a Ni layer and a Sn layer are formed by plating. The connection between the internal electrode and the electrode made of Ag utilizes the Kirkendall effect.

JP 2001-135501 A

  However, the technique described in Patent Document 1 has a problem that a connection failure occurs between the internal electrode and the base electrode.

  Therefore, the present invention has been made in view of the above circumstances, and its purpose is to secure a good electrical connection between the internal electrode and the base electrode while protecting the surface of the element body with a glass layer. An object of the present invention is to provide a ceramic multilayer electronic component and a method for manufacturing the same.

  In order to achieve the above object, a ceramic multilayer electronic component according to the present invention includes an element body mainly made of ceramics, an internal electrode provided inside the element body and protruding from the end face of the element body, and an end face of the element body. A first ground electrode formed; a glass layer covering the surface of the first ground electrode and the element body; a second ground electrode formed on the glass layer in a portion corresponding to an end surface of the element body; The internal electrode passes through the first base electrode and the glass layer and reaches the second base electrode.

  In the above configuration, the first base electrode is formed inside the glass layer at the end face of the element body. The first base electrode functions as a metal supply source for the internal electrode to protrude and reach the second base electrode due to the Kirkendall effect. In the present invention, since the internal electrode passes through the first base electrode and the glass layer and reaches the second base electrode, the electrical connection between the internal electrode and the second base electrode is sufficiently ensured. . Preferably, the internal electrode reaches the inside of the second base electrode.

  Preferably, the internal electrode and the first base electrode contain Ag and / or Pd, and the content of Pd in the first base electrode is smaller than that of the internal electrode. As a result of the study by the inventors of the present application, the knowledge that Ag moves toward an electrode having a large amount of Pd has been obtained. By the above configuration, Ag moves from the first base electrode to the internal electrode, Protrusion of the internal electrode is promoted.

  Preferably, the softening point of the frit (glass component) of the first base electrode is lower than the softening point of the glass layer. Usually, the glass layer is fired at a temperature higher than the softening point of the glass layer. Therefore, by satisfying the softening point condition described above, the frit of the first base electrode is softened by the firing of the glass layer, and the first base electrode is easily penetrated by the internal electrode.

  Furthermore, in order to achieve the above object, a method for manufacturing a ceramic multilayer electronic component according to the present invention includes a multilayer structure including an element body mainly made of ceramics and an internal electrode embedded in the element body and exposed at an end face of the element body. Forming the first base electrode on the end face of the element body, forming the glass layer covering the surface of the first base electrode and the element body, and firing the glass layer And forming a second base electrode on the glass layer in a portion corresponding to the end face of the element body.

  In the present invention, the first base electrode is formed inside the glass layer at the end face of the element body. When the glass layer is baked in this state, metal atoms move from the first base electrode to the internal electrode due to the Kirkendall effect, and the end of the internal electrode protrudes outward. As a result, the end portion of the internal electrode penetrates the first base electrode, which is a metal supply source, and further reaches the inside of the glass layer, and preferably also penetrates the glass layer. Thereafter, when the second base electrode formed on the glass layer is fired, the internal electrode further protrudes and reaches the second base electrode, thereby ensuring electrical continuity with the internal electrode. Preferably, the internal electrode reaches the inside of the second base electrode.

  The softening point of glass is higher than the firing temperature of the second base electrode. By doing so, the glass layer is not softened when the second base electrode is baked, and sticking between the chips can be prevented.

  After the step of forming the second base electrode, the method further includes a step of forming a terminal electrode on the second base electrode by plating. In the present invention, since the surface of the element body other than the covering portion of the second base electrode is protected by the glass layer, erosion of the element body by the plating solution for forming the terminal electrode is prevented.

  According to the ceramic multilayer electronic component and the manufacturing method thereof of the present invention, the first base electrode is formed inside the glass layer, and the first base electrode functions as a metal supply source for protruding the internal electrode. Therefore, the internal electrode can surely penetrate the glass layer, and a good connection between the internal electrode and the second base electrode can be ensured.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios. Further, the following embodiments are exemplifications for explaining the present invention, and are not intended to limit the present invention only to the embodiments. Furthermore, the present invention can be variously modified without departing from the gist thereof.

<First Embodiment>
FIG. 1 is a cross-sectional view showing a schematic structure of a ceramic multilayer electronic component according to a first embodiment of the present invention.
The ceramic multilayer electronic component 1 has a multilayer body 4 including an element body 2 made of ceramics and a plurality of internal electrodes 3 formed in the element body 2. More specifically, the internal electrode 3 having an end protruding from one side surface (end surface) of the element body 2 and the internal electrode 3 having an end protruding from the other side surface of the element body 2 are the element body. 2 are alternately stacked.

  A first base electrode 5 is provided on both side surfaces of the element body 2 so as to cover those side surfaces, and each first base electrode 5 is an internal electrode 3 protruding from one side surface of the element body 2. Or a group of internal electrodes 3 exposed from the other surface of the element body 2.

  A glass layer 6 that covers the element body 2 and the first base electrode 5 is formed on the surface of the element body 2. A second base electrode 7 is formed on the glass layer 6 at portions corresponding to both side surfaces of the element body 2. Each of the second base electrodes 7 is formed into a group of internal electrodes 3 protruding from the glass layer 6 on one side surface of the element body 2 or a group of internal electrodes 3 protruding from the glass layer 6 on the other surface of the element body 2. Electrically connected.

  On the surface of the second base electrode 7, a terminal electrode 8 composed of a Ni layer 8a and a Sn layer 8b is further formed by plating. These terminal electrodes 8 and, for example, electrodes on the wiring board are joined by solder or the like.

Hereinafter, each component will be described.
The element body 2 is made of ceramics, and specifically needs to be made of semiconductor ceramics or dielectric ceramics. Such a ceramic material is not limited, and examples thereof include barium titanate, boron nitride, ferrite, lead zirconate titanate, silicon carbide, silicon nitride, steatite, zinc oxide, and zirconia. In particular, in the case of zinc oxide, the effect of the present invention is remarkable. Zinc oxide is preferably used as an element of a multilayer chip varistor, but has poor chemical resistance and is easily dissolved by a plating solution during plating. In addition, since the electrical resistance is low, plating adheres to the surface of the element body, resulting in frequent appearance defects. In addition, the flux reduces zinc oxide on the element surface during solder mounting, causing an increase in leakage current. By using the present invention, all of the above three problems can be solved.

  A method for synthesizing the ceramic powder used for forming the element body 2 is not particularly limited, and for example, a hydrothermal method, a hydrolysis method, a coprecipitation method, a solid phase method, a sol-gel method, or the like is used. And may be calcined as necessary.

  The internal electrode 3 preferably contains Pd and / or Ag. The internal electrode 3 is formed by printing a conductive paste containing such a metal component.

  The first base electrode 5 functions as a metal supply source for protruding the internal electrode 3 by the Kirkendall effect, and preferably contains Ag and / or Pd. More preferably, the content of Pd in the first base electrode 5 is preferably smaller than that of the internal electrode 3. As a result of the study by the inventors of the present application, it was found that Ag moves toward an electrode having a large amount of Pd. Therefore, Ag moves from the first base electrode 5 to the internal electrode 3 by the above configuration. This is because the protrusion of the internal electrode 3 is promoted. In addition, when the glass layer 6 is baked, the softening point of the frit of the first base electrode 5 is lower than the softening point of the glass layer 6 so that the internal electrode 3 can easily penetrate the first base electrode 5. Is preferred.

  The glass layer 6 is formed in order to prevent erosion of the ceramic body 2 and precipitation of plating metal on the surface of the ceramic body 2 during the plating of the Ni layer 8a and the Sn layer 8b. A small composition is preferred. In order to sufficiently protect the element body 2 while allowing the protrusion of the internal electrode 3, the thickness of the glass layer is preferably 0.5 to 10 μm. A glass having a higher softening point is preferred. Specifically, the softening point of glass is preferably 600 ° C. or higher. Generally, the higher the softening point of the glass, the smaller the dissolution by the plating solution, and the higher the firing temperature, the larger the protrusion of the internal electrode, so that the glass layer 6 can be easily penetrated by the internal electrode 3 when the glass is fired.

  The material of the second base electrode 7 is not particularly limited, and for example, it is formed of the same material as that of the first base electrode 5. The softening point of the frit of the second base electrode 7 is also preferably smaller than the softening point of the glass of the glass layer 6. This facilitates the protrusion of the internal electrode during firing of the second base electrode, and can reach the second base electrode more reliably.

  The terminal electrode 8 is composed of a stacked body of a Ni layer 8a and a Sn layer 8b. The Ni layer 8a functions as a barrier metal that prevents the Sn layer 8b and the second base electrode 7 from interdiffusion during mounting to cause soldering failure, and has a thickness of, for example, about 1 to 3 μm. is there. The Sn layer 8b has a function of improving the wettability of the solder, and the thickness thereof is, for example, about 2 to 4 μm. The Ni layer 8a and the Sn layer 8b are formed using electroplating. In order to prevent the glass layer 6 from being eroded during electroplating, the pH of the plating solution is preferably 5 or more and 12 or less. Moreover, the composition which does not contain a chelating agent in a plating solution is preferable.

  Next, a method for manufacturing the ceramic multilayer electronic component 1 according to the present embodiment will be described with reference to FIGS. 2-6 is process drawing which shows an example of the procedure which manufactures the ceramic multilayer electronic component 1. FIG.

First, as shown in FIG. 2, a laminated body 4 having a laminated structure of an element body 2 and internal electrodes 3 is formed. The laminated body 4 is manufactured as follows, for example.
A ceramic powder, an organic solvent, an organic binder, a plasticizer, and the like are mixed to form a ceramic slurry, and then molded by a doctor blade method to obtain a sheet-like body, a so-called ceramic green sheet.
Subsequently, a pattern of the internal electrode 3 is formed by screen printing a conductive paste containing Pd and / or Ag as a metal component on the ceramic green sheet. Further, subsequently, a plurality of element bodies 2 in which the internal electrodes 3 are formed and a plurality of element bodies 2 in which the internal electrodes 3 are not formed are alternately laminated, and further pressed to obtain a laminated structure.
Then, the laminated structure is divided into individual laminated bodies 4 by cutting. Thereby, the edge part of the internal electrode 3 will be in the state exposed from the side surface of the laminated body 4 after a cutting | disconnection.
Next, the laminate 4 is subjected to a binder removal treatment in the air and then fired to obtain a sintered laminate 4.

  Next, as shown in FIG. 3, a conductive paste containing, for example, Ag and / or Pd as a metal component is applied to the side surface of the element body 2 and baked to form the first base electrode 5. Depending on the firing conditions at this time, the end 3a of the internal electrode 3 may protrude toward the base electrode due to the Kirkendall effect. FIG. 3 shows a state in which the internal electrode 3 has not yet penetrated the first base electrode 5 for the sake of simplification of the description, but the present invention is not limited to this.

  Next, as shown in FIG. 4, a glass slurry containing glass powder, a binder resin and a solvent is applied to the entire surface of the first base electrode 5 and the element body 2 to form a glass coating film 6a. The glass slurry is applied by, for example, a barrel spray method.

  Next, as shown in FIG. 5, the glass layer 6 is formed by baking the glass coating film 6a above the softening temperature of the glass coating film 6a. By firing above the softening point of the glass, a dense and high-density glass film is formed. At the time of firing, metal atoms move from the first base electrode 5 to the internal electrode 3 due to the Kirkendall effect, and the end portion 3a of the internal electrode 3 protrudes outward. As a result, the end 3a of the internal electrode 3 penetrates the first base electrode 5 which is a metal supply source, and preferably also penetrates the glass layer 6.

  At this time, an electrode containing Ag and / or Pd is formed as the internal electrode 3 and the first base electrode 5, and the content of Pd in the first base electrode 5 is made lower than that of the internal electrode 3. Thus, it is known that the movement of Ag from the first base electrode 5 to the internal electrode 3 is promoted, and thereby the protrusion of the internal electrode 3 is promoted. Further, by forming the first base electrode 5 containing a frit having a softening point lower than the softening point of the glass layer 6, the frit of the first base electrode 5 is softened when the glass layer is fired. The first base electrode 5 is easily penetrated by the internal electrode 3.

  Next, as shown in FIG. 6, the second base electrode 7 is formed on the glass layer 6 in portions corresponding to both side surfaces of the element body 2. For example, a conductive paste containing Ag and / or Pd as a metal component is applied and baked to form the second base electrode 7. Since the end 3a of the internal electrode 3 protrudes from the surface of the glass layer 6, the internal electrode 3 and the second base electrode 7 are reliably electrically connected.

  In the subsequent steps, as shown in FIG. 1, the Ni electrode 8 a and the Sn layer 8 b are sequentially deposited on the surface of the second base electrode 7 by electroplating to form the terminal electrode 8. For example, in the formation of the Ni layer 8a, a barrel plating method is adopted, and 2 μm of Ni is deposited using a watt bath. Further, in the formation of the Sn layer 8b, a barrel plating method is adopted, and Sn is deposited by 4 μm using a neutral tin plating bath. Thus, the ceramic multilayer electronic component 1 is manufactured.

  According to the ceramic multilayer electronic component 1 having the above-described configuration, the internal electrode 3 passes through the first base electrode 5 and the glass layer 6 and reaches the second base electrode 7. Good electrical connection with the two underlying electrodes 7 can be ensured.

  Further, according to the method for manufacturing the ceramic multilayer electronic component 1 described above, the first base electrode 5 is formed inside the glass layer 6, so that the glass layer and the second base electrode are fired at the time of firing. The metal atom moves from the first base electrode 5 to the internal electrode 3 by the Kendall effect, and the end 3a of the internal electrode 3 can be projected outward. As a result, the end 3 a of the internal electrode 3 penetrates the glass layer 6, and electrical conduction between the internal electrode 3 and the second base electrode 7 can be ensured.

<Second Embodiment>
FIG. 7 is a cross-sectional view of the ceramic multilayer electronic component 1 according to the second embodiment.
As shown in FIG. 7, this embodiment is the same as the first embodiment except that the end 3a of the internal electrode 3 is thick.

  FIG. 8 is a photograph of the vicinity of the end 3a observed using a FIB (Focused Ion Beam) apparatus. In FIG. 8, numerals corresponding to the respective symbols in FIG. 7 are added. FIG. 8 shows the ceramic multilayer electronic component 1 in a state before the second base electrode 7 is formed. As shown in FIG. 8, the internal electrode 3 penetrates the first base electrode 5 and the glass layer 6, and the end portion 3 a of the internal electrode 3 has the width of the internal electrode 3 in the element body 2. You can see that it is thicker. As described above, since the end 3a of the internal electrode 3 is thick, the contact area between the end 3a of the internal electrode 3 and the second base electrode 7 can be increased, and the contact resistance between the two is reduced. be able to.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
The first base electrode 5 was formed on a varistor mainly composed of ZnO having an internal electrode of Pd and an outer shape of 1.6 × 0.8 × 0.4 mm. The first base electrode 5 includes a metal component made of 100% Ag and a frit having a softening point of 580 ° C. The firing temperature of the first base electrode 5 was 670 ° C. A glass slurry containing a binder was applied to the chip by a barrel spray method to form a 6 μm glass coating film 6a on the entire surface of the chip. At this time, the average particle diameter of the glass in the slurry is 0.4 μm, and the softening point is 740 ° C. This chip was baked at 770 ° C. to form a glass layer 6 having a thickness of 4 μm. At this time, as a result of observation using a FIB (Focused Ion Beam) apparatus, it was confirmed that the internal electrode 3 penetrated the first base electrode 5 and the glass layer 6 and was exposed to the surface. Next, a second base electrode 7 was formed in substantially the same position as the first base electrode 5 by the same method. At this time, as a result of observation using the FIB apparatus, it was confirmed that the internal electrode 3 reached the inside of the second base electrode 7. Next, 2 μm of the Ni layer 8 a was formed on the second base electrode 7 by a watt-based pH 5.5 solution and 4 μm of the Sn layer 8 b was formed using a neutral Sn plating solution of pH 5.5 on the second base electrode 7. At this time, the terminal conduction failure was 0/100.

(Comparative Example 1)
A ceramic multilayer electronic component was manufactured in the same manner as in Example 1 except that the first base electrode 5 was not formed. At this time, the conduction failure between the terminals was 100/100. As a result of observation using the FIB apparatus, it was confirmed that the internal electrode 3 did not penetrate the glass layer 6. It is considered that the cause of the conduction failure is that there is no silver supply source when the internal electrode 3 protrudes because there is no first base electrode 5.

(Comparative Example 2)
A ceramic multilayer electronic component was produced in the same manner as in Example 1 except that glass having a softening point of 645 ° C. was used. At this time, the conduction failure of the terminal was 37/100. As a result of observation using the FIB apparatus, it was confirmed that the protrusion of the internal electrode 3 was insufficient. The cause of the conduction failure is considered to be that the protrusion of the internal electrode 3 due to the Kirkendall effect was not sufficient because the softening point of the glass was low.

  The present invention includes a thermistor, a capacitor, an inductor, a LTCC (Low Temperature Co-fired Ceramics), a varistor, a ceramic multilayer electronic component composed of a composite part thereof, and a device, an apparatus, a system, a facility, and the like including the same, and It can be widely used for their production.

It is a schematic sectional drawing of the ceramic multilayer electronic component which concerns on 1st Embodiment. It is process sectional drawing which shows an example of the procedure which manufactures a ceramic multilayer electronic component. It is process sectional drawing which shows an example of the procedure which manufactures a ceramic multilayer electronic component. It is process sectional drawing which shows an example of the procedure which manufactures a ceramic multilayer electronic component. It is process sectional drawing which shows an example of the procedure which manufactures a ceramic multilayer electronic component. It is process sectional drawing which shows an example of the procedure which manufactures a ceramic multilayer electronic component. It is a schematic sectional drawing of the ceramic multilayer electronic component which concerns on 2nd Embodiment. It is a figure which shows the cross-sectional photograph of the edge part vicinity of an internal electrode.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Ceramic laminated electronic component, 2 ... Element body, 3 ... Internal electrode, 3a ... End part, 4 ... Laminated body, 5 ... 1st base electrode, 6 ... Glass layer, 6a ... Glass coating film, 7 ... 2nd Base electrode, 8 ... terminal electrode, 8a ... Ni layer, 8b ... Sn layer.

Claims (6)

An element made mainly of ceramics,
An internal electrode provided inside the element body and projecting from an end face of the element body;
A first base electrode formed on an end face of the element body;
A glass layer covering a surface of the first base electrode and the element body;
A second base electrode formed on the glass layer in a portion corresponding to the end face of the element body,
The internal electrode reaches the second base electrode through the first base electrode and the glass layer;
Ceramic multilayer electronic components. The internal electrode and the first base electrode include Ag and / or Pd,
The Pd content in the first base electrode is smaller than the internal electrode;
The ceramic multilayer electronic component according to claim 1. The softening point of the frit of the first base electrode is lower than the softening point of the glass layer;
The ceramic multilayer electronic component according to claim 1 or 2. Forming a multilayer structure including an element body mainly made of ceramics, and an internal electrode embedded in the element body and exposed at an end surface of the element body;
Forming a first base electrode on an end face of the element body;
Forming a glass layer covering a surface of the first base electrode and the element body;
Firing the glass layer;
Forming a second base electrode on the glass layer at a portion corresponding to the end face of the element body. The softening point of the glass is higher than the firing temperature of the second base electrode,
The manufacturing method of the ceramic multilayer electronic component of Claim 4. After the step of forming the second base electrode, the method further includes the step of forming a terminal electrode on the second base electrode by plating.
The manufacturing method of the ceramic multilayer electronic component of Claim 4.