JPH1116766A - Manufacture of laminated ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent inner structural failures such as delamination, cracking and the like from occurring in a laminated ceramic electronic component by a method, wherein nickel powder as the main component of inner electrode paste is specified in average grain diameter and specific surface ratio. SOLUTION: Nickel powder 0.5 to 0.6 μm in average grain diameter and 2.5 m<2> /g or less in specific surface ratio is used as the main component of nickel electrode paste used for the inner electrode of a laminated ceramic electronic component. Ethyl cellulose, mineral sprit, and terpineol are added to the nickel powder, kneaded, and dispersed into paste, and the paste is made to pass through a sieve which is 15 μm or less in apertures, whereby the agglomerates of nickel powder are removed. By this setup, an inner structural failures such as delamination and cracking can be restrained from occurring in a laminated ceramic electronic component, when it is baked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer ceramic electronic component.

[0002]

2. Description of the Related Art A conventional method for manufacturing a multilayer ceramic electronic component will be described by taking a multilayer ceramic capacitor as an example.

First, a ceramic green sheet (hereinafter, referred to as a green sheet) is prepared by using a slurry obtained by kneading a dielectric ceramic raw material powder, an organic binder, and an organic solvent. On the other hand, nickel electrode paste for internal electrodes (hereinafter, referred to as
An electrode paste) is prepared by kneading and dispersing nickel powder, ethyl cellulose, mineral spirit, terpineol, and the like using a roll kneader. Next, the electrode paste is applied to the green sheet surface by screen printing to obtain a green sheet on which internal electrodes are formed by evaporating and drying a solvent component in the electrode paste. Next, after laminating a predetermined number of the green sheets on which the electrodes are formed, and by applying heat and pressure to form a laminated green block, the green sheets are cut and separated into a predetermined shape to form a laminated green chip. Then, the separated laminated green chip is sintered and porcelain at a predetermined firing temperature, and a conductive material such as silver is applied to both exposed end surfaces of the internal electrodes to form external electrodes, thereby forming a multilayer ceramic capacitor. Was getting.

[0004]

In the above conventional method,
Due to the variation of firing shrinkage of nickel powder and the effect of agglomerates of nickel powder, internal structure defects such as delamination and fire Cracks tend to increase inside the multilayer ceramic capacitor sintered body, and even if there are no internal structural defects, the insulation resistance failure rate in the characteristic selection process increases, reducing the yield. Had a point.

[0005]

In order to solve the above-mentioned problems, the present invention provides a nickel powder as a main component of a paste for an internal electrode used for an electronic component such as a multilayer ceramic capacitor having an average particle size of 0.5 to 0.5. A powder having a diameter of 0.6 μm and a specific surface area of 2.5 m ² / g is used.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention relates to a nickel powder mainly composed of a nickel electrode paste used for an internal electrode of a multilayer ceramic electronic component and having an average particle size of 0.5 to 0.6 μm. And the specific surface area is 2.5 m ² /
g or less of powder. Nickel powder in the above range can easily match the firing shrinkage behavior with the base ceramic.Therefore, even in the case where the thickness of the dielectric layer of the multilayer ceramic capacitor is reduced or the layer thickness is increased, the oxidative expansion and expansion of the nickel powder, which is the main component of the internal electrode, are increased. It is possible to suppress the shrinkage behavior, reduce the occurrence of internal structural defects and firing cracks during firing of the laminated green chip, and obtain a dense and low-sintered sintered body.

According to a second aspect of the present invention, there is provided a sieve having an opening diameter of 15 μm or less after kneading and dispersing the nickel powder of the first aspect by adding ethylcellulose, mineral spirit and terpineol, and forming a paste. To remove aggregates of the nickel powder. By removing agglomerates of nickel powder particles in the electrode paste after kneading with the binder and plasticizer, the smoothness of the internal electrode surface printed on the green sheet surface is obtained, and the green sheet coated with the internal electrode is laminated In addition, the adhesiveness at the time of pressing is improved, and the aggregate of nickel powder in the printed internal electrode does not cause the local part of the green sheet to become thin or crack at the time of pressing and pressing, and the sintered laminated ceramic Insulation resistance failure of the capacitor can be reduced, and a highly reliable multilayer ceramic capacitor can be obtained.

Hereinafter, an embodiment of the present invention will be described by taking a multilayer ceramic capacitor as an example. First, a predetermined amount of polyvinyl butyral as a binder, dibutyl phthalate as a plasticizer, and methyl ethyl ketone as a solvent were added to a ceramic powder containing barium titanate as a main component, and a slurry mixed with a ball mill was used for a roll coating method to form an effective layer. A green sheet having a thickness of 7 μm and an invalid layer of 50 μm is prepared.

On the other hand, as an internal electrode paste, (Table 1)
After adding predetermined amounts of ethylcellulose, mineral spirit and terpineol to the nickel powder having the average particle size and specific surface area shown in (1), and kneading and dispersing them in a roll kneader, the paste was filtered as shown in (Table 1). The mixture was passed through a sieve under the conditions to prepare a nickel electrode paste.

[0010]

[Table 1]

Next, the above-mentioned electrode paste is screen-printed on the surface of the green sheet having a thickness of 7 μm using the electrode paste.
After printing the internal electrode of a predetermined shape, the substrate was dried at a temperature of 90 ° C. for 1 minute to prepare a required number of green sheets in which the solvent in the electrode paste was volatilized. Next, when the green sheet is cut and separated into a stacked green chip shape, the internal electrodes are alternately shifted so as to be exposed to different end faces.
One sheet was laminated, and three sheets of the above-mentioned 50 μm green sheet were further laminated on the upper and lower portions thereof, and then pressure-bonded under a pressure of 500 kg / cm ² to produce a laminated green block. After the green block produced in this manner was cut into a predetermined shape, the binder was removed, then transferred to a firing furnace and sintered at 1280 ° C. Thereafter, a silver electrode is applied to the exposed end surface of the internal electrode of the sintered body, and then baked to form an external electrode. Further, the external electrode surface is subjected to a plating process to improve solderability, and laminated. A ceramic capacitor was manufactured. The number of occurrences of internal structural defects, the number of occurrences of insulation resistance failure, and the high-temperature accelerated life test (applied voltage of 4 times the rated voltage in a temperature bath at 85 ° C. for 2000 hours) of the obtained multilayer ceramic capacitor were evaluated. The results are shown in (Table 1).

As shown in (Table 1), the nickel of No. 1
Powder has an average particle size of 0.4 μm and a specific surface area of 2.4 m
^Two/ G, the base ceramic green sheet
Delamination of internal defects due to difference in firing shrinkage
Many cracks occur. No9 has a large average particle size
When the specific surface area is small, no internal structural defects occur
However, the variation in the capacitance becomes extremely large. But,
The reason is not clear. In contrast, the average grain of the present invention
0.5-0.6μm diameter and 2.5m specific surface area ^Two/ G
In the case of No. 6 to No. 8, smaller internal structural defects occur.
And low incidence of IR failure, and high temperature load life
Life test results are also satisfactory. However average
No. 2 having a large specific surface area even if the particle size is 0.5 μm
Fabrication defects occur. On the other hand, the average particle size is 0.5 μm and the specific surface
Product is 2.5m^Two/ G less than / g
After the electrode paste is kneaded, the aggregated particles of nickel powder
Not filtered with Louis or full with an opening diameter of 15μm or more
Filtration in (a), lamination due to the effect of aggregated particles of nickel powder
Green sheet is locally thinned and insulation resistance is poor.
Incidence rate and failure rate rate in high temperature load life test increase
You can see that As mentioned above, the base green sea
The average particle size is easily adjusted to match the firing shrinkage rate.
Using a nickel powder in the range of 5 to 0.6 μm,
Use a sieve with an opening diameter of 15 μm or less for nickel powder
By filtering and removing the agglomerated particles at the end, internal structural defects and
And the occurrence rate of insulation resistance failure is low.
, A dense and excellent laminated
A lamic capacitor can be obtained. The present invention
Method of manufacturing multilayer ceramic capacitor as one embodiment
Was explained, but the materials listed in the
By changing the combination of the thickness of the sheet, the number of layers, the firing conditions, etc.
Has no effect on its effectiveness.

[0013]

As described above, the average particle size and specific surface area of the nickel powder, which is the main component of the internal electrode, are controlled even when the dielectric layer green sheet is thinned or highly laminated as shown in the present invention. Thereby, the firing shrinkage behavior due to oxidation and reduction of the nickel powder is suppressed, and the firing shrinkage rate can be matched with the green sheet, and the occurrence of delamination and cracks of internal structural defects during firing is reduced,
It is possible to obtain a dense and low-strain sintered body. In addition, by filtering the kneaded electrode paste, the aggregated particles of the nickel powder are removed, the smoothness of the printed internal electrode surface is obtained, and the adhesion of the green sheet at the time of laminating and pressurization and the aggregated particles are caused by the aggregated particles. Is not locally thinned, and insulation resistance failure can be reduced.
A highly reliable multilayer ceramic capacitor can be obtained.

Claims (2)

[Claims] A nickel powder as a main component of a nickel electrode paste used for an internal electrode of a multilayer ceramic electronic component has an average particle size of 0.5 to 0.6 μm and a specific surface area of 2.5 m ² / g or less. A method for producing a multilayer ceramic electronic component, comprising using powder. 2. The nickel powder according to claim 1, to which ethyl cellulose, mineral spirit and terpineol are added, kneaded and dispersed, and after forming a paste, the opening diameter becomes 1.
A method for manufacturing a multilayer ceramic electronic component using an electrode paste from which agglomerates of nickel powder have been removed by passing through a sieve of 5 μm or less.