JP2003151805A - Chip element component and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip electronic component that is improved in durability by means of a glass coating layer formed as a protective layer, can secure continuity between internal and external electrodes, and is excellent in yield and electric characteristics, and to provide a method of manufacturing the component. SOLUTION: On at least a part of the surface of a chip-type sintered laminate 15, glass coating layers 16 each having a thicknesses of 0.05-5 μm are provided. In addition, on surfaces of both end sections of the laminate 15, external electrodes 19 of which the mean thickness is three times or more larger than that of the layer 16 and baked at a temperature lower than the softening point of the layer 16 and higher than an operating temperature are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip type electronic component and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in order to protect an element from the outside atmosphere, a protective film has been provided on the outer peripheral portion thereof (Japanese Patent Application Laid-Open Nos. 5-251210 and 5-2815).
3206 publication).

In Japanese Unexamined Patent Publication (Kokai) No. 5-251210, a thermistor base chip is ground to round corners and ridges, and then a glass film is formed on the surface of the thermistor base chip, and then an electrode material paste coating film is formed. When baking
By lowering the working temperature of the glass below the baking temperature, a protective film is provided on the thermistor base chip.

Further, in JP-A-5-283206, a thickness of 0.1 μm to the entire surface of the conductive ceramic body is
Baking by coating a 2 μm insulating inorganic layer, applying a conductive paste containing metal powder and an inorganic binder to both ends of the ceramic body, and firing at a temperature lower than the melting point or softening point of the inorganic layer. A protective film is provided on the surface of the ceramic body other than the contact portion of the electrode layer.

[0005]

However, in the conventional chip-type electronic component disclosed in Japanese Unexamined Patent Publication No. 5-251210, glass floats on the surface of the electrode during baking of the electrode paste, or the ceramic bodies are burned together or with the body. There is a problem that sticking to the jig occurs, defective products are generated, and the yield is reduced.

Further, in Japanese Unexamined Patent Publication No. 5-283206, there is a problem that even after baking the conductive paste, a defective product in which the electrode layer and the ceramic body are not electrically connected to each other is produced and the yield is reduced.

According to the present invention, glass as a protective layer is prevented from floating on the surface of the electrode during baking of the electrode paste, and sticking of the ceramic bodies to each other or between the body and the firing jig is prevented. An object of the present invention is to provide a chip-type electronic component having a stable electrical connection with a ceramic body, a good yield, and excellent electrical characteristics, and a method for manufacturing the same.

[0008]

In order to solve the above-mentioned problems, a chip-type electronic component of the present invention comprises a chip-type ceramic element body and a thickness of at least a part of the surface of the ceramic element body. A glass coat layer having a thickness of 0.05 μm to 5 μm, and an average thickness that is three times or more the thickness of the glass coat layer on both end surfaces of the ceramic body, and
An external electrode having physical properties formed by baking the glass coat layer at a softening point or higher and a working temperature or lower.

The ceramic body is made of a semiconductor ceramic containing barium titanate as a main component and having a positive resistance temperature characteristic, and an internal electrode electrically connected to the external electrode formed on one end surface of the ceramic body. It is preferable that the internal electrodes electrically connected to the external electrodes formed on the other end surface are alternately embedded inside the ceramic body.

The manufacturing method of the chip type electronic component of the present invention is as follows.
In order to solve the above problems, at least a part of the surface of a chip-type ceramic body is coated with a glass coating layer with a thickness of 0.05 μm to 5 μm, and both ends of the ceramic body are covered with an external material. It is characterized in that the electrode has an average thickness three times or more that of the glass coat layer and is formed by baking at a softening point of the glass coat layer or higher and a working temperature or lower.

According to the above structure and method, the thickness of the glass coat layer is set to 0.05 μm to 5 μm, and the average thickness of the external electrodes is set to 3 times or more the thickness of the glass coat layer. This makes it possible to prevent the glass coating layer from floating and to reduce the resistance between the external electrode and the ceramic body while allowing the glass coating layer to function as a protective film. Therefore, with the above configuration and method, it is possible to improve the yield and provide excellent electrical characteristics.

The glass coat layer has a thickness of 0.05 μm.
When it is less than m, for example, when the external electrode is plated, the ceramic body also undergoes plating growth, and the glass coat layer does not serve as a protective film.

When the thickness of the glass coat layer is thicker than 5 μm, the glass of the glass coat layer cannot be mixed with the electrode material of the external electrode, and the resistance between the ceramic body and the external electrode is significantly increased. . Further, if the average thickness of the external electrode is less than three times that of the glass coat layer, the glass coat layer may have a disadvantage that the glass floats when the electrode material for the external electrode is baked.

Further, regarding the baking temperature of the electrode material for the external electrode, if the glass of the glass coating layer is below the softening point of the glass, the glass of the glass coating layer and the electrode material cannot be completely mixed, and the ceramic body and the outside On the other hand, when the resistance between the electrode and the electrode is significantly increased, and when the temperature is higher than the working temperature of the glass, the glass floats when the electrode material is baked.

In the chip-type electronic component, when the ceramic body is made of semiconductor ceramics having a positive resistance temperature characteristic (PTC), which is required to be reduced in room temperature resistance value, a glass coat functioning as a protective layer. Since the layer is provided stably, it has excellent environmental resistance, and also has a chip-type electronic component that can reduce the resistance between the external electrode and the ceramic body and has excellent electrical characteristics.
It is effective because it can exhibit excellent durability and electrical characteristics in a particularly stable manner.

[0016]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to FIG. In this embodiment, a chip-type electronic component is a chip-type PTC (Positive Temperature Coe).
fficient) Thermistor will be described as an example.

First, the ceramic of the chip type PTC thermistor
BaCO as a raw material ₃, TiO₂, Sm
₂O₃Each powder of (Ba_0.9998Sm_0.0002) TiO₃When
It was mixed so that Next, pure water was added to the obtained powder mixture.
And crush with zirconia balls for 16 hours
Then, after drying, it was calcined at 1200 ° C. for 2 hours.

An organic binder, a dispersant, and water were added to the calcined powder and mixed with zirconia balls for several hours, and then a green sheet was formed. Next, Ni paste serving as an internal electrode was applied to one surface of the green sheet by a method such as a printing method.

Thereafter, the Ni pastes applied in layers are stacked so that the Ni pastes face each other via the green sheets and are not in contact with each other (separated so as not to conduct electricity), and further the protective green sheets are vertically arranged ( A laminate was prepared by arranging the green sheets in the thickness direction of the green sheet).

A raw chip of a substantially rectangular parallelepiped shape obtained by pressing the above-mentioned laminated body in the thickness direction thereof and cutting it into a certain size,
Dry barrel polishing was performed to obtain rounded raw chips with rounded corners and ridges.

Ni paste was attached to both end surfaces (each end surface where each Ni paste is exposed) of this rounded green chip by dipping or the like and dried to form each end surface Ni.

Then, 1 rounded green chip having each layered Ni paste and each end face Ni inside is formed.
Firing at 200 ° C. in a reducing atmosphere of H ₂ / N ₂ = 3%,
As shown in FIG. 1A, a fired laminated body (ceramic body) 15 having a substantially rectangular parallelepiped shape was obtained.

The firing laminate 15 corresponds to the internal electrodes 11 and 12 corresponding to the respective Ni pastes, which are spaced apart from each other and faced in parallel in a comb shape, and the respective end faces Ni. , 12 respectively having end face electrodes 13 and 14 electrically connected to them. In other words, the fired laminated body 15 is an electric circuit element having an electrical function such as a barium titanate-based PTC thermistor, and usually has a pair of terminal electrodes for external connection. is there.

Next, the above-mentioned baking is performed on an aqueous solution containing glass having a softening point of 500 ° C. to 800 ° C., a working temperature of 800 ° C. to 1150 ° C., and a softening point lower than the baking temperature of the electrode material described later and a high working temperature. After the entire laminated body 15 is immersed, it is dried and further heat-treated at 500 ° C. to 600 ° C. to have a thickness of about 0.5 as shown in FIG.
The glass coating layer 16 having a thickness of μm to 5 μm is formed on the fired laminate 1
Sintered chips 17 formed on the entire outer surface of No. 5 were obtained.

The softening point is the temperature at which the glass used has a viscosity of 10 ^7.5 poise (10 ^6.5 Pa · s).
The working temperature is 10 ⁴ poise (10 ³ P)
This is the temperature at which the viscosity reaches a.s). The softening point and working temperature of the glass were changed depending on the composition of the glass.

The glass composition is SiO ₂ , Li.
_{Using 2} O, Na ₂ O and K ₂ O, the softening point and working temperature were changed mainly by the ratio of Si to the alkali metal element. Further, the thickness of the glass coat layer 16 was changed by changing the concentration of the glass-containing aqueous solution or repeating the glass immersion, drying and heat treatment.

Both ends of the sintered chip 17 on which the glass coat layer 16 is formed (on the surfaces corresponding to the end electrodes 13 and 14)
The electrode material paste consisting of Ag powder, binder, etc. is applied by dipping or printing and then dried.
Baking was performed at 00 ° C. to form the external electrodes 19 on both ends, as shown in FIG.

At the time of this baking, the electrode material and the glass of the glass coat layer 16 are intermingled and mixed between each external electrode 19 and each end surface electrode 13, 14 and each end surface electrode 13, 14 is mixed. In the above, since the glass coat layer 16 becomes the island-shaped glass portion 16a, the electrode films of the external electrodes 19 and the end face electrodes 13 and 14 come into contact with each other and are electrically connected to each other.

At this time, since the baking temperature is not less than the softening point of the glass used for the glass coat layer 16 and not more than the working temperature, the surface of the sintered tip 17 other than the electrode material paste forming portion is not covered. Is formed as a protective layer so that the glass coat layer 16 can be covered without gaps.

Thereafter, a metal plating layer 20 which is sequentially plated with Ni and Sn is formed on each of the external electrodes 19 by a normal method, and the chip according to the present embodiment is also rounded. A type PTC thermistor 18 was obtained.

The thickness of the glass coat layer and the external electrode, the softening point of the glass coat layer and the working temperature were changed, and the appearance of each chip type PTC thermistor was evaluated and the room temperature resistance was measured. The results are shown in Table 1.

[0032]

[Table 1]

In Table 1, No. marked with * is added. 7-1
1 is outside the scope of claims of the present invention (comparative example). No.
In Nos. 7 and 8, the thickness of the glass coat layer was outside the scope of the claims of the present invention, and No. In No. 9, the thickness of the external electrode is outside the scope of the claims of the present invention, and No. 9 The electrode material baking temperatures of 10 and 11 are outside the scope of the claims of the present invention.

As is clear from Table 1, the thicknesses of the glass coating layer and the external electrode and the baking temperature of the electrode material are within the scope of the claims of the present invention. Nos. 1 to 6 (Examples) have excellent properties such as no plating growth on the ceramic body during plating, no glass float during baking of the electrode material, and low room temperature resistance.

On the other hand, the chip-type PTC thermistor having the thickness of the glass coat layer outside the scope of the claims of the present invention, No. 7, 8
No. In No. 7, plating growth on the ceramic body occurred during plating, and No. 7 In 8, the room temperature resistance increased.

Further, the chip type PTC thermistor having the thickness of the external electrode outside the scope of the claims of the present invention, No. In No. 9, glass float was observed, and the room temperature resistance was significantly increased. In addition, a chip type PTC thermistor having a baking temperature of the electrode material outside the scope of the claims of the present invention, No. Nos. 10 and 11 are Nos.
In No. 10, the electrical connection between the external electrode and the end face electrode of the ceramic body was not established, and the room temperature resistance was significantly increased.
In No. 11, glass float was observed, and the room temperature resistance was also significantly increased.

The chip-type electronic component according to the present invention is
The present invention is not limited to the above-mentioned embodiments and examples, but can be variously modified within the scope of the gist thereof.
Other than C thermistors, especially multilayer capacitors, varistors,
It can also be applied to chip-type ceramic electronic components such as ferrite.

The size (dimensions) of such a chip-type electronic component is not particularly limited, but is 20 m.
m (length) x 20 mm (width) x 10 mm (height) or less is preferable, and 10 mm (length) x 10 mm (width) x 5 mm
(Height) or less is more preferable. Furthermore, the thickness of the external electrode 19 is preferably 50 μm or less. Even if the thickness of the external electrode is more than 50 μm, there is no particular effect and it is uneconomical.

The chip-type electronic component according to the present invention, particularly the chip-type PTC thermistor, can be suitably used for an electronic device such as an overcurrent prevention device and a communication device such as a mobile phone. The electronic device may have excellent durability such as environment resistance, and may have improved electrical characteristics such as low resistance between each of the end face electrodes 13 and 14 and each of the external electrodes 19 corresponding thereto. It will be possible.

[0040]

As described above, the chip-type electronic component of the present invention has a glass coating layer having a thickness of 0.05 to 5 μm coated on at least a part of the surface of the ceramic body and both end portions of the ceramic body. An external electrode having an average thickness three times or more that of the glass coat layer on the surface and having physical properties formed by baking at a softening point of the glass coat layer or higher and a working temperature or lower. is there.

The manufacturing method of the chip type electronic component of the present invention is as follows.
As described above, the glass coat layer having a thickness of 0.05 μm to 5 is formed on at least a part of the surface of the chip type ceramic body.
μm, and the external electrodes on both end surfaces of the ceramic body have an average thickness of 3 times or more that of the glass coat layer, and a softening point of the glass coat layer or more,
This is a method of baking at a working temperature or lower.

Therefore, in the above-described structure and method, the glass coat layer floats up on the surface of the external electrode during the baking of the electrode paste for forming the external electrode, or the ceramic bodies are adhered to each other or the ceramic body and the firing jig are attached to each other. Adhesion is prevented, and the conductive connection between the external electrode and the ceramic body can be stabilized even after the electrode paste is baked, so that the yield can be improved and excellent electrical characteristics can be exhibited.

[Brief description of drawings]

FIG. 1A to FIG. 1C are schematic diagrams showing a chip-type electronic component and a method for manufacturing the same according to the present invention.

[Explanation of symbols]

11, 12 Internal electrode 13, 14 Edge electrode 15 Fired laminated body (ceramic body) 16 Glass coat layer 17 Sintered chips 18 chip type laminated PTC thermistor 19 External electrode 20 Metal plating layer

Claims (3)

[Claims] 1. A chip-type ceramic body, a glass coat layer having a thickness of 0.05 μm to 5 μm, which covers at least a part of the surface of the ceramic body, and both end surfaces of the ceramic body, A chip having an average thickness three times or more that of the glass coat layer, and an external electrode having physical properties formed by baking at a softening point of the glass coat layer or higher and a working temperature or lower. Mold electronic components. 2. The ceramic body is made of a semiconductor ceramic containing barium titanate as a main component and having a positive resistance temperature characteristic, and is electrically connected to the external electrode formed on one end surface. 2. The chip type according to claim 1, wherein electrodes and internal electrodes electrically connected to the external electrodes formed on the other end surface are alternately embedded inside the ceramic body. Electronic components. 3. A glass coat layer having a thickness of 0.05 .mu.m to 5 .mu.m on at least a part of the surface of the chip type ceramic body.
m, and external electrodes are provided on the surfaces of both end portions of the ceramic body.
A method for manufacturing a chip-type electronic component, which has an average thickness three times or more that of the glass coat layer, and is formed by baking at a softening point of the glass coat layer or higher and a working temperature or lower.