JP3223910B2 - Multilayer ceramic electronic components - Google Patents

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 such as a multilayer ceramic capacitor.

[0002]

2. Description of the Related Art A multilayer ceramic capacitor will be described below as a conventional multilayer ceramic electronic component.

First, a ceramic sheet made of a dielectric material such as barium titanate and an organic binder component is prepared. Next, a conductor layer is formed on the ceramic sheet using a conductor paste. Next, a desired number of the ceramic sheets on which the conductor layers are formed are stacked such that the conductor layers face each other with the ceramic sheet interposed therebetween, and a laminated body in which the respective layers are adhered is obtained. This laminate is fired, and external electrodes are provided at both ends to form a multilayer ceramic capacitor.

[0004]

In recent years, multilayer ceramic capacitors have been rapidly reduced in size and capacity, and in order to achieve these requirements, attempts have been made to reduce the thickness of ceramic sheets and further increase the number of layers. Has been made. However, in the step of forming a conductor layer on a thin ceramic sheet or the step of laminating the conductor layers so that the conductor layers face each other with the ceramic sheet interposed therebetween, metal particles contained in the conductor paste are not only present on the surface of the ceramic sheet but also on the surface thereof. ,
It reaches the inside of the ceramic sheet through the gap between the ceramic particles. When the ceramic sheet is particularly thin, the metal component may penetrate the ceramic sheet, and in this case, after lamination and firing, it will be in a short state,
There is a problem that the function as a capacitor is not fulfilled. Even if the short-circuit state does not occur, a portion where the conductor layer is close to the conductor is liable to be deteriorated or broken in a life test or a withstand voltage test, which is a major cause of deterioration in quality.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a multilayer ceramic electronic component with less short-circuit failure by preventing a metal component from entering a ceramic sheet.

[0006]

According to the present invention, there is provided a laminate comprising a ceramic sheet comprising ceramic powder and an organic substance and a conductor layer alternately laminated to form a laminate.
In a multilayer ceramic electronic component in which external electrodes are provided at both ends of the fired laminate, the ceramic sheet
Is less than 10 μm, is a multilayer ceramic electronic component in which the average particle size of the metal component in the conductor layer is larger than the average particle size of the ceramic powder, and can prevent the metal component from entering the inside of the ceramic sheet. , Short-circuit defects can be reduced.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is characterized in that a ceramic sheet made of ceramic powder and an organic substance and a conductor layer are alternately laminated to form a laminate, and the laminate is fired. In the multilayer ceramic electronic component provided with external electrodes at both ends, the ceramic sheet has a thickness of 10 μm.
m, wherein the average particle size of the metal component in the conductor layer is larger than the average particle size of the ceramic powder, and a multilayer ceramic electronic component with less short circuit failure can be provided. .

According to a second aspect of the present invention, there is provided the multilayer ceramic electronic component according to the first aspect, wherein at least a part of the metal component is scaly, and the penetration of the metal component into the ceramic sheet is further suppressed. can do.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking a multilayer ceramic capacitor as an example.

(Embodiment 1) FIG. 1 is an enlarged sectional view of a main part of a ceramic sheet 12 and a conductor layer 13 formed on a base film 11 in this embodiment, FIG. 2 is an overall sectional view of FIG. FIG. 3 is a partially cutaway perspective view of a general multilayer ceramic capacitor. 1 is a ceramic dielectric layer, 2
Is an internal electrode, 3 is an external electrode, and the internal electrodes 2 are connected to the external electrodes 3 respectively.

Next, a method of manufacturing a multilayer ceramic capacitor according to the present embodiment will be described.

First, a dielectric material powder mainly composed of barium titanate and having an average particle diameter of 0.7 μm, a polyvinyl butyral binder component, dibutyl phthalate as a plasticizer component, and butyl acetate as a solvent component are mixed. After slurrying, using a doctor blade method, FIGS. 1 and 2
As shown in the figure, a base film 11 such as a polyethylene terephthalate film (hereinafter referred to as a PET film)
The ceramic sheet 12 was formed thereon.

Next, the conductor layer 1 is placed on the ceramic sheet 12.
As No. 3, a nickel paste was formed in a predetermined pattern by a printing method or the like, and dried to produce a ceramic sheet 14 with a conductor layer. The nickel paste contains an organic binder component in addition to a spherical nickel powder having an average particle diameter of 0.8 μm and a solvent. The solvent is aliphatic naphtha,
The aromatic naphtha, terpineol, and organic binder components are ethyl cellulose. Since most of the solvent in the conductor layer 13 is scattered by drying, the conductor layer 1 after drying is dried.
3 is only a metal component and an organic binder component. At this time, the thickness of the ceramic sheet 12 is 8 μm,
Was 2.0 μm in thickness.

In order to compare the effect of controlling the average particle size of the nickel powder on the average particle size of the dielectric material, the average particle size of the nickel powder is set to 0.7 μm, 0.9 μm, 1.0 μm,
Ceramic sheets 14 with conductor layers shown in FIGS. 1 and 2 were similarly produced using a nickel paste having a thickness of μm.

Further, in order to investigate the influence of the shape of the nickel powder, a nickel paste having a scale shape and an average particle diameter of 0.8 μm was used, and the ceramic having the conductor layer shown in FIGS. Sheet 14 was produced. In addition,
The thickness of the conductor layer 13 after drying is 2.0 to 2.1, respectively.
μm, which was almost the same.

Next, each of the ceramic sheets 14 with a conductor layer was laminated 100 times by thermal transfer, and then cut into 3.5 mm length and 2.0 mm width to obtain a laminate. Thermal transfer is 100 ° C, 100kg / c using a uniaxial press.
It was carried out in m ^2.

Thereafter, the laminate was fired at 1300 ° C. in an atmosphere of N ₂ and H ₂ to obtain a sintered body. The thickness of the ceramic dielectric layer 1 after firing was all 4.5 μm, and no structural defect was present inside the sintered body.

Next, external electrodes 3 were formed on both exposed end surfaces of the internal electrodes 2 of the sintered body using a copper paste, and the external electrodes 3 were plated to complete a multilayer ceramic capacitor.

Table 1 shows the results of examining the short-circuit failure rate and breakdown voltage of five types of multilayer ceramic capacitors having different shapes and particle sizes of nickel powder.

[0020]

[Table 1]

The short-circuit failure rate is the occurrence rate when the insulation resistance is judged to be short-circuit when the insulation resistance is several ohms for each of 100 samples, and the breakdown voltage is when the breakdown voltage is measured for 50 samples without short-circuit failure. 2 shows the minimum value and the average value.

As is clear from Table 1, the use of nickel powder having an average particle size equal to or larger than the average particle size of the dielectric material powder contained in the ceramic sheet 12 results in a short-circuit defect rate, a minimum breakdown voltage, It tends to improve at all points of average breakdown voltage. When a nickel powder having a flaky shape is used rather than a spherical shape, the short circuit rate, the minimum breakdown voltage, and the average breakdown voltage tend to be improved in all respects.
Further analysis of the short-circuited portion of the short-circuited defective product revealed that the opposing internal electrodes 2 were short-circuited in all of the short-circuited defective products.

As described above, by using a metal powder having an average particle size larger than the average particle size of the ceramic powder,
It can be seen that it is possible to suppress the metal powder from penetrating into the ceramic sheet 12 and to suppress the occurrence of a fatal defect such as a short circuit defect or a withstand voltage defect for the multilayer ceramic electronic component. In addition, it can be seen that when the metal component has the same average particle size, the flaky shape is less likely to penetrate into the ceramic sheet 12 than the spherical shape.

The average particle size used here is not limited to the measuring method, and the effect can be expected when the metal powder is larger in the relative particle size between the ceramic powder and the metal powder. .

Further, by making the minimum particle size of the metal powder larger than the minimum particle size of the ceramic powder, the penetration of the metal component into the ceramic sheet 12 can be further suppressed.

Furthermore, even when the primary particle size of the metal powder is smaller than the average particle size of the ceramic powder, the metal component in the metal paste that becomes the conductive layer 13 when the conductive layer 13 is laminated with the ceramic sheet 12 is laminated. Are secondary aggregated, and the same effect can be obtained as long as the aggregate is larger than the ceramic powder and hardly disassembled.

Although the thickness of the ceramic sheet 12 is made constant in the first embodiment, the same effect can be obtained with any thickness. In particular, when the thickness of the ceramic dielectric layer 1 after firing is less than 10 μm, the effect is remarkable.

Also, only the case where a laminate in which a conductor layer 13 is formed on a ceramic sheet 12 formed on a base film 11 to obtain a laminate is described.
Similar effects can be obtained in the following cases. (1) In the case of forming a laminate by alternately laminating the ceramic sheet 12 and the conductor layer 13 (2) Laminate the conductor layer 13 formed on the base film 11 and thermally transferring it on the ceramic sheet 12. Further, in the case of forming a multilayer body, the above embodiment has been described with respect to a multilayer ceramic capacitor, the present invention is a general multilayer ceramic electronic component having a lamination step of laminating a conductor layer and a ceramic layer, for example, The present invention can be applied to a multilayer chip varistor, a multilayer coil, and a multilayer substrate, and can suppress short circuit failure and breakdown voltage failure.

[0029]

As described above, according to the present invention, there is provided a multilayer ceramic electronic component which has extremely few places where conductor layers opposing each other with a ceramic dielectric layer interposed therebetween are extremely close to each other, and has few short-circuit defects and high breakdown voltage. be able to.

[Brief description of the drawings]

FIG. 1 is a partially enlarged cross-sectional view of a ceramic sheet and a conductor layer formed on a base film according to an embodiment of the present invention.

FIG. 2 is an overall sectional view of FIG. 1;

FIG. 3 is a partially cutaway perspective view of a general multilayer ceramic capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic dielectric layer 2 Internal electrode 3 External electrode 11 Base film 12 Ceramic sheet 13 Conductor layer

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Claims (2)

(57) [Claims] [Claim 1] a ceramic powder and an organic material and by laminating the ceramic sheet and the conductor layer are alternately laminated body consisting, in the multilayer ceramic electronic component providing the external electrode on the end face of those firing the laminate, the ceramic Shi
A multilayer ceramic electronic component having a thickness of less than 10 μm and an average particle diameter of a metal component in the conductor layer larger than an average particle diameter of the ceramic powder. 2. The multilayer ceramic electronic component according to claim 1, wherein the metal component is at least partially scaly.