JP2001110604A - Laminated ceramic electronic component and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated ceramic electronic component of high reliability, in which electric connection of an internal electrode with an external electrode is sure and plating solution is prevented from permeating into an interface between a ceramic layer and the internal electrode in the case of plating, using an easy manufacturing method of low cost. SOLUTION: In this electronic component, an external electrode connected electrically with internal electrode layers is formed on the end surface of a ceramic laminate having a plurality of ceramic layers and the internal electrode layers formed between the ceramic layers, and glass layers are formed on interfaces between the ceramic layers and the internal electrode layers, from the end surface of the ceramic laminate toward the inside. From the glass layers, glass component is diffused, and regions of high resistivity are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic electronic component having an external electrode on an end face of a ceramic laminate having a plurality of ceramic layers and a plurality of internal electrode layers, and more particularly, to an external electrode having an electrolytic plating layer. The present invention relates to a multilayer ceramic electronic component.

[0002]

2. Description of the Related Art As an example of a multilayer ceramic electronic component,
This will be described using a chip thermistor. In a chip-type thermistor, a film made of Ni, Sn, etc. is formed by electroplating on external electrodes baked with a conductive paste such as Ag for the purpose of improving solderability and suppressing Ag erosion. In such a case, there is a problem that the thermistor element near the external electrode is corroded and dissolved to cause a change in resistance value. This is because the plating solution penetrates into the thermistor element through the external electrode in the plating step because the external electrode formed by baking is relatively porous.

Accordingly, the chip type thermistor improves the sealing property of the thermistor element by diffusing glass from the end face of the thermistor element toward the inside, and further forming a glass layer on the end face of the thermistor element. Corrosion of the thermistor element near the external electrode during electrolytic plating is prevented.

[0004] For example, Japanese Patent Application Laid-Open No.
Japanese Patent Publication No. 5063 discloses a multilayer ceramic electronic component 1 as shown in FIG. The multilayer ceramic electronic component 1 is formed by baking on a ceramic laminate 2 including a plurality of ceramic layers 2a, a plurality of internal electrodes 3 formed between the ceramic layers 2a, and an end face of the ceramic laminate 2. External electrodes 4a, 4a and external electrodes 4a, 4a
Plating films 4b, 4b and 4c, 4c formed on
And consisting of Further, glass-rich regions 5a and 5a exist from the end face of the ceramic laminate 2 to the inside, and the end face of the ceramic laminate 2 and the external electrode 4
The glass layers 5b and 5b are formed between the glass layers 5a and 4a.

[0005]

The glass-rich regions 5a and 5a of the multilayer ceramic electronic component 1 are formed by applying a glass paste to an end face of the ceramic laminate 2 and thermally diffusing the paste. In addition, the glass layers 5b, 5
b, when the external electrodes 4a, 4a are baked, a conductive paste containing glass frit of fine particles is baked at a high speed, and a large amount of glass components are present at the interface between the end face of the ceramic laminate 2 and the external electrodes 4a, 4a. It is formed by having

However, according to the above method, the glass paste does not diffuse well into the ceramic laminate 2 or the glass component in the conductive paste does not diffuse well into the end faces of the ceramic laminate 2 and the external electrodes 4a, 4a. May not precipitate at the interface of Then, the internal electrodes 3,
3 and the external electrodes 4a, 4a become unreliable or have insufficient sealing properties, and a plating solution enters the interface between the ceramic layer 2a and the internal electrodes 3, 3 from the end face of the ceramic laminate 2. As a result, electrical characteristics are deteriorated, for example, the ceramic layer 2a and the internal electrodes 3 are easily peeled off.

Furthermore, applying a glass paste to the end face of each sintered ceramic laminate 2 and performing a heat treatment involves a complicated process and a high cost.

SUMMARY OF THE INVENTION It is an object of the present invention to ensure that the internal electrode and the external electrode are electrically connected, and to prevent the plating solution from entering the interface between the ceramic layer and the internal electrode during plating.
An object of the present invention is to provide a highly reliable multilayer ceramic electronic component by an easy and inexpensive manufacturing method.

[0009]

According to a first aspect of the present invention, there is provided a multilayer ceramic electronic component comprising: a ceramic laminated body having a plurality of ceramic layers and an internal electrode layer formed between the ceramic layers; An external electrode electrically connected to the internal electrode layer is formed, and a layer made of an inorganic substance is formed at an interface between the ceramic layer and the internal electrode layer from the end face of the ceramic laminate toward the inside. It is characterized by.

In the multilayer ceramic electronic component according to the second aspect of the invention, the inorganic substance diffuses from a layer made of the inorganic substance formed at the interface between the ceramic layer and the internal electrode layer to form a high resistivity region. It is characterized by having.

[0011] In the multilayer ceramic electronic component according to a third aspect of the present invention, the external electrode has an electrolytic plating layer.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a multilayer ceramic electronic component, comprising the steps of: preparing a ceramic green sheet; and applying a conductive paste inwardly from both ends of the ceramic green sheet. A step of applying an inorganic substance to both ends of the ceramic green sheet so as to cover the upper surface of the conductive paste; a step of laminating, pressing and firing the ceramic green sheets to obtain a ceramic laminate; Forming external electrodes at both ends of the body.

In the method of manufacturing a multilayer ceramic electronic component according to a fifth aspect of the present invention, before the step of applying a conductive paste inward from both ends of the ceramic green sheet, the both ends of the ceramic green sheet are The method further includes a step of applying an inorganic substance.

Thus, the inorganic layer formed at the interface between the ceramic layer and the internal electrode layer prevents the plating liquid from entering along the interface from the end face of the ceramic laminate.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

[0016]

Embodiment 1 An embodiment of the present invention will be described with reference to a chip type negative characteristic thermistor 11 shown in FIG.

The chip type negative temperature coefficient thermistor 11 includes a negative temperature coefficient thermistor body 12 formed by laminating a plurality of ceramic layers 12a, opposing internal electrode layers 13, 13 formed between the ceramic layers 12a, and a negative temperature coefficient thermistor. External electrodes 14 are formed on both end surfaces of the element body 12 so as to be electrically connected to one ends of the internal electrode layers 13.
The external electrodes 14 and 14 are baked electrode layers 14a and 14a.
And plating layers 14b, 14b formed thereon.

A glass layer 15a is formed on at least the upper interface of the interface between the ceramic layer 12a of the negative characteristic thermistor element 12 and the internal electrode layer 13, and furthermore, from the glass layer 15a in the vertical stacking direction. The glass is diffused, and from the end face of the negative temperature coefficient thermistor body 12 toward the inside, a region 15b having a higher specific resistance than the central specific resistance,
15b are formed.

The chip type negative characteristic thermistor 11 is manufactured through the following steps. First, Mn, Ni, Co,
A predetermined amount of an organic binder, a solvent, and the like are added to a thermistor material mainly containing an oxide such as Al, and the thickness is 40 to 60.
A green sheet of μm is prepared and cut into a predetermined size. Next, as shown in FIG. 2, conductive pastes 17, 17 made of Ag-Pd are screen-printed on the surface of the green sheet 16 from both ends toward the inside with a thickness of 1 to 3 μm. This conductive paste 17, 17
Is for forming the internal electrode layers 13 and 13.

Further, on this green sheet 16,
Conductive paste 1 from both ends toward the inside
The glass pastes 18, 18 made of Al—B—Si are screen-printed with a thickness of 5 to 10 μm so as to cover the upper surfaces of the layers 7 and 17. The glass pastes 18 form the glass layer 15a.

The green sheet 1 coated with the conductive pastes 17, 17 and the glass pastes 18, 18
6 are laminated in a required number, and are pressure-bonded by a hydraulic press so as to have a predetermined thickness and integrated. Thereafter, firing is performed at 1200 ° C. Thereby, among the interfaces between the ceramic layer 12a of the negative characteristic thermistor element body 12 and the internal electrode layer 13, the glass layer 15a is formed at least on the upper interface, and a part of the glass components of the glass pastes 18, 18 is vertically Then, regions 15b, 15b having a higher specific resistance than the central specific resistance are formed from the end surface of the negative characteristic thermistor element body 12 toward the inside.

At this time, not all of the glass components of the glass paste 18 applied to the green sheet 16 are diffused, but a certain amount of the glass components remains at the original location, and the firing is performed so that the glass layer 15a is formed. The temperature, firing time, and composition of the glass paste 18 are adjusted in advance.

In FIG. 1, the glass layer 15 a is formed only at the upper interface of the interface between the ceramic layer 12 a and the internal electrode layer 13, but actually, the lower interface is formed by the diffusion of the glass paste 18. It is also preferred that it is formed also.

Further, in FIG. 2, the negative characteristic thermistor body 12 for one chip has been described. However, actually, a plurality of patterns as shown in FIG. Then, a plurality of chip-shaped negative characteristic thermistor bodies 12 are obtained.

Next, external electrodes 14 and 14 are formed on both ends of the negative temperature coefficient thermistor body 12 manufactured by the above method so as to be electrically connected to the internal electrode layers 13 and 13. First, a conductive paste for an external electrode made of Ag is applied as a base layer, and baked at 800 ° C. to form a baked electrode layer 14a.
14a is formed. Furthermore, the baked electrode layers 14a, 14
A plated layer 14b, 14b made of Ni—Sn is formed on the layer a by electrolytic plating to obtain a chip type negative characteristic thermistor 11.

In this chip type negative temperature coefficient thermistor 11, a glass layer 15a is formed at the interface between the ceramic layer 12a and the internal electrode layer 13 from the end face of the negative temperature coefficient thermistor body 12 toward the inside. Compared with the multilayer ceramic electronic component 1 in which the glass layer 5a is formed only on the end face of the ceramic laminate 2, the ceramic layer 1 from the end face of the negative characteristic thermistor element 12 when the plating layers 14b, 14b are formed.
The plating solution does not easily enter the interface between 2a and the internal electrode layer 13. It is more effective if the glass layer 15a is also formed on the lower interface between the ceramic layer 12a and the internal electrode layer 13.

Furthermore, since regions 15b, 15b having a higher specific resistance than the central portion are formed from the end surface of the negative temperature coefficient thermistor body 12 toward the inside, the conventional ceramic laminate 2 end surface is formed. As in the case of the multilayer ceramic electronic component 1 in which the glass-rich regions 5a, 5a are present toward the inside, the plating solution does not easily enter the thermistor body 12 near the external electrodes 14, 14.

[0028]

Embodiment 2 In another embodiment of the present invention, a negative characteristic thermistor body 12 'shown in FIG. 3, and negative characteristic thermistors 11' and 11 'shown in FIGS. 4 (a) and 4 (b). 'Will be explained as a reference. However, the same components as those of the negative characteristic thermistor body 12 and the negative characteristic thermistor 11 of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The negative characteristic thermistor body 12 'is manufactured through the following steps. First, as shown in FIG. 3, a green sheet 16 cut to a predetermined size is prepared, and glass pastes 18 are screen-printed on the surface of the green sheet 16 from both ends inward. Next, conductive pastes 17, 17 are screen-printed inward from both ends, respectively, on the green sheet 16 so as to cover the upper surfaces of the glass pastes 18, 18. Further, the conductive paste 17, 17
A glass paste 18 is applied on the green sheet 16 from both ends inward so as to cover the upper surface of
18 is screen printed. Then, a required number of green sheets 16 coated with the conductive pastes 17 and 17 and the glass pastes 18 and 18 are laminated in a required number, and pressed and integrated with a hydraulic press so as to have a predetermined thickness.
Baking.

According to the method of manufacturing the negative characteristic thermistor body 12 ′, before the step of applying the conductive pastes 17 from both ends of the green sheet 16 in the first embodiment to the inside, the green sheet The method further comprises a step of applying glass pastes 18 on both ends of the ceramic layer 12, so that the ceramic layers 12 a of the negative characteristic thermistor body 12 ′ are formed.
Glass layer 15 on both upper and lower interfaces between
a and 15a can be formed.

A negative-characteristic thermistor using the negative-characteristic thermistor body 12 'will be described with reference to FIGS. 4 (a) and 4 (b). The negative characteristic thermistor 11 'shown in FIG.
The external electrodes 14, 14 electrically connected to the internal electrode layers 13, 13 are formed on both end surfaces of the negative characteristic thermistor element body 12 ′. The negative characteristic thermistor body 12 ′ has glass layers 15 a, 15 a formed on both upper and lower interfaces between the ceramic layer 12 a and the internal electrode layer 13, and has a higher specific resistance from the end face toward the inside as compared with the specific resistance at the center. Resistive area 15
b and 15b are formed.

This negative characteristic thermistor 11 'is the same as that of the first embodiment.
As compared with the negative thermistor 11, the glass layer 15a is surely formed on both upper and lower interfaces between the ceramic layer 12a and the internal electrode layer 13, so that the ceramic layer 12a and the internal electrode layer 13 are not formed when the plating layers 14b and 14b are formed. It is possible to more reliably prevent the plating solution from entering the interface with the substrate.

Similarly to the negative temperature coefficient thermistor 11 of the first embodiment, since the high specific resistance regions 15b, 15b are formed from the end face of the negative temperature coefficient thermistor body 12 'toward the inside, the external electrodes 14, It is difficult for the plating solution to enter the negative characteristic thermistor body 12 ′ near 14.

The negative characteristic thermistor 1 shown in FIG.
1 ″ are external electrodes 14, 1 electrically connected to the internal electrode layers 13, 13 on both end surfaces of the negative characteristic thermistor body 12 ′.
4 are formed. The negative characteristic thermistor body 12 ′
Glass layers 15a, 15a are formed on both upper and lower interfaces between the ceramic layer 12a and the internal electrode layer 13.

The negative characteristic thermistor 11 ″ has almost no glass component diffused therein, and the negative characteristic thermistor body 12 ′
From the end surface of the region toward the inside, regions 15b, 1
5b is not formed. However, like the negative characteristic thermistor 11 of the first embodiment, the negative characteristic thermistor body 12
The glass layer 15a is formed at the upper and lower interfaces between the ceramic layer 12a and the internal electrode layer 13 from the end face of the ceramic layer 12a toward the inside, so that the interface between the ceramic layer 12a and the internal electrode layer 13 when the plating layers 14b and 14b are formed. It is possible to reliably prevent the plating solution from entering the plating.

In the first and second embodiments, a glass paste 18 is applied to the green sheet 16, and the glass layer 15a and the glass component are placed inside the negative characteristic thermistor element 12 and the negative characteristic thermistor element 12 '. The diffused high resistivity region 15b was formed.
trivalent or higher metal oxide such as i, Ti, Sn, etc., or Zn,
A material having a higher specific resistance than a thermistor element containing at least one of Al, W, Zr, Sb, Y, Sm, Ti, and Fe may be used.

The multilayer ceramic electronic component of the present invention is not limited to the negative characteristic thermistor of the embodiment, but may be a positive characteristic thermistor or a capacitor.

[0038]

As described above, in the multilayer ceramic electronic component of the present invention, a layer made of an inorganic material such as glass is formed at the interface between the ceramic layer and the internal electrode layer from the end face of the ceramic laminate to the inside. Since it is formed, it is possible to prevent the plating solution from entering the interface between the ceramic layer and the internal electrode layer when the electrolytic plating layer is formed.

In addition, since the inorganic substance diffuses from the layer made of the inorganic substance toward the inside from the end face of the ceramic laminate to form a region having a high specific resistance, the plating solution is baked when the electrolytic plating layer is formed. Intrusion into the ceramic laminate through the layers can be prevented.

From the above, it is possible to prevent corrosion of the ceramic laminate near the external electrodes and peeling of the internal electrodes during electrolytic plating, and prevent a change in characteristics of the multilayer ceramic electronic component due to electrolytic plating and deterioration of mechanical strength.

Further, an inorganic material is applied to each green sheet, laminated, pressed, and fired to form a layer made of the inorganic material and a region having a high specific resistance. The electrical connection with the electrodes is secure, the manufacturing process is simple, and the cost is low.

[Brief description of the drawings]

FIG. 1 is a sectional view of a chip type negative temperature coefficient thermistor according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view illustrating a stacked state of the negative temperature coefficient thermistor body of FIG. 1;

FIG. 3 is an exploded perspective view showing a modification of the stacked state of FIG. 2;

FIGS. 4A and 4B show the chip type negative temperature coefficient thermistor according to FIG. 2, wherein FIG.
FIG. 3 is a cross-sectional view when the glass paste has not diffused.

FIG. 5 is a cross-sectional view of a conventional multilayer ceramic electronic component.

[Explanation of symbols]

 11, 11'11 '' Negative characteristic thermistor 12, 12 'Negative characteristic thermistor body 12a Ceramic layer 13 Internal electrode layer 14 External electrode 14a Burning electrode layer 14b Plating layer 15a Glass layer 15b High resistivity region 16 Green sheet 17 Conductive Paste 18 Glass paste

Claims (5)

[Claims] An external electrode electrically connected to the internal electrode layer is formed on an end surface of a ceramic laminate having a plurality of ceramic layers and an internal electrode layer formed between the ceramic layers, A multilayer ceramic electronic component, wherein a layer made of an inorganic substance is formed at an interface between the ceramic layer and the internal electrode layer from the end face of the ceramic laminate toward the inside. 2. The high-resistivity region, wherein the inorganic substance diffuses from a layer made of the inorganic substance formed at the interface between the ceramic layer and the internal electrode layer. Of multilayer ceramic electronic components. 3. The multilayer ceramic electronic component according to claim 1, wherein the external electrode has an electrolytic plating layer. 4. A step of preparing a ceramic green sheet, a step of applying a conductive paste inward from both ends of the ceramic green sheet, and a step of coating the ceramic green sheet so as to cover an upper surface of the conductive paste. A step of applying an inorganic substance to both ends of the ceramic green sheet, a step of laminating, pressing and firing the ceramic green sheets to obtain a ceramic laminate, and a step of forming external electrodes at both ends of the ceramic laminate. A method for manufacturing a multilayer ceramic electronic component, comprising: 5. Prior to the step of applying a conductive paste inward from both ends of the ceramic green sheet,
The method for manufacturing a multilayer ceramic electronic component according to claim 4, further comprising a step of applying an inorganic substance to both ends of the ceramic green sheet.