JP3064659B2 - Manufacturing method of multilayer ceramic element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a multilayer ceramic element for protecting semiconductor elements such as ICs and LSIs and electronic circuits from abnormally high voltages such as noise, pulses and static electricity generated in electronic equipment and electric equipment. it relates to.

[0002]

2. Description of the Related Art In recent years, semiconductor devices such as ICs and LSIs have been widely used for realizing miniaturization and multifunction of electronic equipment and electric equipment. The proof stress against abnormal high voltage such as is low. Therefore, film capacitors, electrolytic capacitors, semiconductor ceramic capacitors, multilayer ceramic capacitors, etc. are used to ensure the withstand capability of these electronic and electrical devices against abnormal high voltages such as noise, pulses, and static electricity. Although it exhibits excellent characteristics in absorbing and suppressing relatively low noise and high frequency noise, it has no effect on high voltage pulses or static electricity, and may cause malfunction or destruction of a semiconductor element.

In order to absorb and suppress high-voltage pulses and static electricity, SiC and ZnO-based varistors are used. However, they have no effect on absorbing and suppressing relatively low-voltage noise and high-frequency noise. The device may malfunction. Japanese Patent Application Laid-Open No. 57-27001 and Japanese Patent Application Laid-Open No. 57-35
As disclosed in Japanese Patent Publication No. 303, an SrTiO ₃ ceramic element having both capacitor characteristics and varistor characteristics has been developed and used.

On the other hand, in the field of electronic components, the development of chip components that can be surface-mounted has become indispensable as lighter, thinner, smaller, and higher performance have been developed in response to miniaturization of devices. Corresponding to these, JP-A-54-53248, JP-A-54-53250, and JP-A-59-21
Although there are examples of lamination type shown in Japanese Patent Application Laid-Open No. 5701 and Japanese Patent Application Laid-Open No. 63-219115, these methods are complicated in process or the obtained characteristics are insufficient to achieve the purpose. However, it has not yet reached the stage of practical use.

Therefore, as a multilayer ceramic element having both practical capacitor characteristics and varistor characteristics, a grain boundary insulating semiconductor ceramic capacitor and a method of manufacturing the same have been proposed in Japanese Patent Application Laid-Open No. Hei 3-1516. The contents are as follows.

[0006] The grain boundary insulating semiconductor ceramic condensate
Sa is Sr_(1-x)Ba_xAnd the molar ratio of Ti is 0.95 ≦ Sr
_(1-x)Ba_x/Ti<1.00
Sr contained_(1-x)Ba_xTiO_Three(However, 0 <x ≦
0.3), Nb_TwoO_Five, Ta_TwoO _Five, V_TwoO_Five, W_TwoO_Five, D
y_TwoO_Three, Nd_TwoO_Three, Y_TwoO_Three, La_TwoO_Three, CeO_TwoWithin
0.05 to 2.0 mol% of at least one kind,
Mn and Si are replaced by MnO_TwoAnd SiO_TwoConverted to total
0.2-5.0 mol% in amount and NaAlO_Two0.0
5 to 4.0 mol% of the composition.
You.

In the production method, first, a mixed powder of this composition is used as a starting material, and the mixed powder is pulverized, mixed and dried, and then calcined in air or a nitrogen atmosphere. After calcination, the ground powder is dispersed in a solvent together with an organic binder in a solvent to form a raw sheet, and then the internal electrode paste is printed on the raw sheet so as to alternately reach opposite edges (however, the uppermost layer). And without printing on the lower raw sheet).

Next, the green sheet on which the internal electrode paste is printed is laminated, pressed and pressed to obtain a molded body, and then the molded body is calcined in the air. Then, after calcining, firing in a reducing or nitrogen atmosphere, and re-oxidizing in the air, an external electrode paste is applied to both ends where the internal electrodes are exposed and baked to produce.

[0009]

However, in the conventional multilayer ceramic element, various material compositions and manufacturing methods have been developed as shown in the above-mentioned conventional example.
In each case, there was a problem that the process was complicated or the obtained characteristics were insufficient to achieve the purpose, and thus the product did not reach the level of practical use. Further, the new multilayer ceramic element disclosed in Japanese Patent Application Laid-Open No. Hei 3-1516 has a problem that electric characteristics change with time due to adsorption of moisture in the air and the like, and moisture resistance is insufficient. .

The present invention solves the above-mentioned conventional problems, and provides a multilayer ceramic element having stable electric characteristics and excellent moisture resistance, and a method for manufacturing the same by a relatively easy manufacturing method that can be put into practical use. It is intended to do so.

[0011]

In order to achieve the above object, a method for manufacturing a multilayer ceramic element according to the present invention comprises the steps of:
And two types with different average particle diameters
Preparing a raw sheet of a kind such that the average particle diameter is small;
Laminating a plurality of raw sheets, and the average
Multiple layers of raw sheet with large particle size and internal electrode layer alternately
A step of laminating, and a green sheet having a small average particle diameter
After laminating multiple sheets, press and crimp to form a compact
After firing the compact in a reducing atmosphere
An oxidizing step and a step of forming an external electrode.
It is.

[0012]

[0013]

According to this method, the laminated ceramic element is
The upper and lower ceramic layers are higher than the inner ceramic layer
Since the density is increased, the porosity of the surface of the multilayer ceramic element is reduced, and moisture or the like in the air is less likely to be adsorbed or absorbed inside the ceramic layer. Therefore, deterioration of apparent surface resistance of the ceramic layer is suppressed. And the moisture resistance can be remarkably improved.

[0014]

[0015]

[0016]

The present invention will be described below in more detail with reference to examples.

(Embodiment 1) FIG. 1 is a sectional view of a multilayer ceramic element according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a ceramic layer mainly containing strontium titanate, and reference numerals 1a and 1b denote a lowermost layer and an uppermost layer of the ceramic layer 1, respectively. However, the components of the lowermost layer 1a and the uppermost layer 1b contain more glass components than the components of the internal ceramic layer 1. Reference numeral 2 denotes an internal electrode layer made of Pd, which is alternately arranged with the ceramic layer 1, and one end of which is drawn alternately to a different edge of the ceramic layer 1. Reference numeral 3 denotes external electrodes formed at both ends so as to be electrically connected to the edge of the internal electrode layer 2.
The outside has a three-layer structure of solder.

A method for manufacturing the multilayer ceramic element having the above-described structure will be described below. FIG. 2 is an exploded perspective view showing a laminated state of raw sheets in the manufacturing process.
Reference numeral 4 denotes a raw sheet A, 4a and 4b, which will be described below, and a raw sheet B, and 5 denotes an internal electrode layer.

First, as a first component, SrCO_Three, CaC
O_Three, TiO_TwoTo (Sr_0.98Ca_0.02)_0.995TiO_ThreePair of
99.2 mol% as a composition ratio, as the second component
Nb _TwoO_Five0.3 mol%, and MnCO as the third component_ThreeTo
0.2 mol%, Cr_TwoO_Three0.1 mol%, as the fourth component
T SiO_TwoWeighed 0.2 mol%
After mixing for 40 hours, pulverizing and drying, 900 ° C in air
And calcine for 2 hours again with a ball mill etc. for 50 hours
And pulverize so that the average particle size is 1.0 μm or less.
You. The powder obtained in this way contains butyral resin
A binder is mixed with an organic solvent to form a slurry,
50 thickness by sheet forming method such as
Obtain a raw sheet of about μm, cut it into
A4.

Next, as the first component, SrCO_Three, CaC
O_Three, TiO_TwoTo (Sr_0.98Ca_0.02)_0.995TiO_ThreePair of
98.1 mol% so as to have a composition ratio, as the second component
Nb _TwoO_Five0.3 mol%, and MnCO as the third component_ThreeTo
0.2 mol%, Cr_TwoO_Three0.1 mol%, as the fourth component
T SiO_Two0.4 mol%, and Na as the fifth component_TwoSiO
_ThreeWeigh 0.9 mol% and use a ball mill or the like for 40 hours
After mixing, pulverizing and drying, the mixture is air dried at 900 ° C for 2 hours.
Calcined, mixed and crushed again by a ball mill for 50 hours
So that the average particle size becomes 1.0 μm or less. like this
Organic binder such as butyral resin to the powder obtained
Mixer and organic solvent to make a slurry,
Approximately 50μm thick by sheet forming method such as blade method
Raw sheet B4, and cut into a predetermined size to obtain a raw sheet B4.
a, 4b.

Next, a predetermined number of raw sheets B4a to be the lowermost layer 1a are laminated, a raw sheet A4 is laminated thereon, and an internal electrode layer 5 made of Pd or the like is formed by screen printing or the like. A4 lamination and internal electrode layer 5
And a predetermined number of sheets are laminated alternately. At this time, the internal electrode layers 5 are printed so as to alternately face each other and reach different edges. And the raw sheet B to be the uppermost layer 1b
A predetermined number of 4b are laminated, pressed and crimped while heating, and cut into a predetermined shape.

Next, degreased calcined at 800 ° C. for 4 hours in the air, for example, in a reducing atmosphere of N ₂ : H ₂ = 9: 1.
After calcination at 50 ° C. for 4 hours, reoxidation is performed at 950 ° C. for 2 hours in air. Thereafter, an external electrode paste made of Ag or the like is applied to both end surfaces where the internal electrode layers 2 are alternately exposed to different edges, and baked at 800 ° C. for 10 minutes in air. Next, Ni plating is performed on the Ag electrode by, for example, an electrolytic method,
Further, the external electrodes 3 are formed by solder plating.

With respect to the thus-obtained multilayer ceramic element sample, electrical characteristics were measured and a reliability test in moisture was conducted. However, the measured electrical characteristics were measured at 0.
The voltage V generated across the sample when a current of 1 mA flows
_The capacitance C and tan δ of the sample at _{0.1 mA} and a frequency of 1 kHz. In addition, the reliability test under humidity was 85 ° C.
The test was performed under the conditions of a temperature of 85 ° C., a humidity of 85 RH%, a charge rate of 90%, and a standing time of 500 hours. Changes in the voltage V _{0.1 mA} and the capacitance C before and after the test were compared. The power application rate is a value obtained by dividing the voltage applied to the sample by the voltage V _{0.1 mA} .

The measurement results are shown in (Table 1). However test for [Delta] V _{0.1 mA} is a representation of the ratio of the difference between the voltage V _{0.1 mA} values before and after the test with respect to the voltage V _{0.1 mA} values before the test as a percentage, [Delta] C is the capacitance C value before test in (Table 1) The ratio of the difference between the front and rear capacitance C values is expressed as a percentage.

In Table 1, for comparison with the conventional one,
The electrical characteristics and the results of a reliability test in wet conditions of a device manufactured by the same method as that described in JP-A-3-1516 are also shown as a conventional example.

[0026]

[Table 1]

As is apparent from Table 1, the lowermost layer 1a
Also, by forming the uppermost layer 1b using raw sheets B4a and 4b containing a large amount of glass components such as SiO ₂ and Na ₂ SiO ₃ , a dense layer is formed, so that moisture is less likely to be adsorbed and reliability in wet conditions is improved. It is possible to realize a multilayer ceramic element having extremely excellent moisture resistance, in which the electrical characteristics hardly change even when the test is performed.

(Embodiment 2) FIG. 3 is a perspective view of a multilayer ceramic element according to a second embodiment of the present invention. 3, 6 is an external electrode similar to the external electrode 3 shown in FIG.
Reference numeral 7 denotes a ceramic coating layer that covers the surfaces of the uppermost layer and the lowermost layer. A method for manufacturing such a multilayer ceramic element will be described below.

First, a predetermined number of the raw sheets A used in Example 1 for forming the lowermost layer are laminated. Next, Pd
An internal electrode layer made of, for example, is formed by screen printing, and a predetermined number of raw sheets A and internal electrode layers are alternately laminated. At this time, the internal electrode layers are printed so as to alternately face each other and reach different edges. Then, a predetermined number of the raw sheets A are stacked for forming the uppermost layer, and the raw sheets A are pressurized and pressed under heating to be cut into a predetermined shape.

Next, the molded body after the cutting is subjected to 80 in air.
After degreased calcining at 0 ° C. for 4 hours, for example, firing at 1250 ° C. for 4 hours in a reducing atmosphere of N ₂ : H ₂ = 9: 1, and reoxidizing at 950 ° C. for 2 hours in air to obtain a sintered body Get. Thereafter, an external electrode paste made of Ag or the like is applied to both ends of the sintered body in which the internal electrode layers are alternately exposed at different edges, and baked in air at 800 ° C. for 10 minutes.

Next, as the first component, SrCO_Three, CaC
O_Three, TiO_TwoTo (Sr_0.98Ca_0.02)_0.995TiO_ThreePair of
96.0 mol% so as to have a composition ratio, as the second component
Nb _TwoO_Five0.3 mol%, and MnCO as the third component_ThreeTo
0.2 mol%, Cr_TwoO_Three0.1 mol%, as the fourth component
T SiO_TwoIs 1.4 mol%, and the fifth component is Na_TwoSiO
_ThreeWeigh 2.0 mol%, and use a ball mill or the like for 40 hours.
After mixing, pulverizing and drying, the mixture is air dried at 900 ° C for 2 hours.
Calcined, mixed again with a ball mill for 90 hours, pulverized
Then, the coating agent D is adjusted so that the average particle size becomes 1.0 μm or less.
Make it. Then, coat the top and bottom surfaces of the sintered body
The cloth material D is coated with Ag by a method such as screen printing.
Apply at 800 ° C in air
For 10 minutes. Further, for example, electrolysis is performed on the Ag electrode.
External electrode 6 by applying Ni plating and solder plating by
Form.

The results of the electrical property measurement and the reliability test in wet conditions of the thus obtained multilayer ceramic element as in Example 1 are shown in Table 2.

[0033]

[Table 2]

As shown in Table 2, according to this embodiment, the coating material D containing a large amount of the glass component is applied to the surfaces of the uppermost layer and the lowermost layer of the sintered body after reduction firing, and then fired. By forming the ceramic coating layer 7, tan δ is remarkably improved as compared with the conventional example shown in (Table 1), and the change in the electrical characteristics by the reliability test under humidity is extremely small.

Further, the formation of the ceramic coating layer 7 on the surfaces of the uppermost layer and the lowermost layer suppresses moisture and the like in the air from being adsorbed and absorbed inside the ceramic layer, and prevents the moisture and the like in the ceramic layer from being absorbed into the side surfaces and the external electrode portions. Is coating agent D
By applying no coating, gas components generated when the internal ceramic layer is debindered can easily escape to the outside, effectively eliminating delamination, pinholes, blisters, cracks and remaining undecomposed components. Thus, it is possible to eliminate structural defects of the multilayer ceramic element and to stabilize electrical characteristics.

(Example 3) A predetermined number of the raw sheets A used in Example 1 were laminated for forming the lowermost layer, and an internal electrode layer made of Pd or the like was formed thereon by screen printing or the like. A and a predetermined number of internal electrode layers are alternately laminated. At this time, the internal electrode layers are printed so as to alternately face each other and reach different edges. Then, a predetermined number of the raw sheets A are laminated for forming the uppermost layer, and pressure and pressure are applied while heating.
Cut into a predetermined shape.

Next, degreased calcining is performed in the air at 800 ° C. for 4 hours, for example, in a reducing atmosphere of N ₂ : H ₂ = 9: 1.
After calcination at 250 ° C. for 4 hours, re-oxidation is performed in air at 950 ° C. for 2 hours to obtain a sintered body. Thereafter, an external electrode paste made of Ag or the like is applied to both end surfaces where the internal electrode layers are alternately exposed at different edges, and baked at 800 ° C. for 10 minutes in air.

Next, as the first component, SrCO_Three, CaC
O_Three, TiO_TwoTo (Sr_0.98Ca_0.02)_0.995TiO_ThreePair of
95.0 mol% so as to have a composition ratio, as the second component
Nb _TwoO_Five0.3 mol%, and MnCO as the third component_ThreeTo
0.2 mol%, Cr_TwoO_Three0.1 mol%, as the fourth component
T SiO_Two1.6 mol%, and Na as the fifth component_TwoSiO
_Three2.8 mol% of the weighed product, and 40 hours by a ball mill etc.
After mixing, pulverizing and drying, the mixture is air dried at 900 ° C for 2 hours.
Calcined, mixed again with a ball mill for 90 hours, pulverized
Then, the coating agent E is adjusted so that the average particle size becomes 1.0 μm or less.
Make it.

Next, a resist made of, for example, an organic resin is applied to the Ag electrode portion of the sintered body, dried at 150 ° C. for 5 minutes, immersed in a coating material E, and then dried.
After drying at 10 ° C. for 10 minutes, the resist is immersed in an organic solvent such as toluene to remove the resist at the Ag electrode portion. Then, it is baked at 800 ° C. for 10 minutes in the air. Next, Ni plating and solder plating are performed on the Ag electrode by, for example, an electrolytic method.

The results of the measurement of electrical characteristics and the reliability test in wet conditions of the thus-obtained multilayer ceramic element as in Example 1 are shown in Table 3.

[0041]

[Table 3]

As shown in Table 3, according to the present embodiment, the coating material E containing a large amount of the glass component was applied to the surface of the sintered body after reduction firing except for the end surface where the internal electrode layer was exposed. By forming the ceramic coating layer by post-firing, tan δ is remarkably improved as compared with the conventional example shown in (Table 1).
Also, the change in electrical characteristics due to the reliability test in wet conditions is extremely small.

(Example 4) A predetermined number of the raw sheets A used in Example 1 were laminated for forming the lowermost layer, and an internal electrode layer made of Pd or the like was formed thereon by screen printing or the like. A and a predetermined number of internal electrode layers are alternately laminated. At this time, the internal electrode layers are printed so as to alternately face each other and reach different edges. Then, a predetermined number of the raw sheets A are laminated for forming the uppermost layer, pressed and pressed under heating to form a molded body, and cut into a predetermined shape.

Next, as the first component, SrCO_Three, CaC
O_Three, TiO_TwoTo (Sr_0.98Ca_0.02)_0.995TiO_ThreePair of
98.5 mol% as the second component
Nb _TwoO_Five0.3 mol%, and MnCO as the third component_ThreeTo
0.2 mol%, Cr_TwoO_Three0.1 mol%, as the fourth component
T SiO_Two0.4 mol%, and Na as the fifth component_TwoSiO
_ThreeWeigh 0.5 mol% and use a ball mill or the like for 40 hours.
After mixing, pulverizing and drying, the mixture is air dried at 900 ° C for 2 hours.
Calcined, mixed again with a ball mill for 90 hours, pulverized
So that the average particle diameter becomes 1.0 μm or less;
And

Next, a coating agent F is applied to the surfaces of the uppermost layer and the lowermost layer of the molded article by, for example, screen printing so as not to adhere to the exposed portions of the internal electrode layer, and then dried. At 800 ° C. for 4 hours, for example, at 1250 ° C. in a reducing atmosphere of N ₂ : H ₂ = 9: 1.
After calcining for an hour, reoxidize in air at 950 ° C. for 2 hours. Thereafter, an external electrode paste made of Ag or the like is applied to both end surfaces where the internal electrode layers are alternately exposed at different edges, and baked at 800 ° C. for 10 minutes in air. Next, Ag
Ni plating and solder plating are applied to the electrodes by, for example, an electrolytic method.

The results of the electrical property measurement and the reliability test in wet conditions of the multilayer ceramic element thus obtained in the same manner as in Example 1 are shown in Table 4.

[0047]

[Table 4]

As shown in Table 4, according to the present embodiment, the coating agent F containing a large amount of glass components was applied to the surfaces of the uppermost layer and the lowermost layer of the molded article after lamination, and then fired to form a ceramic. By forming the coating layer, the change in the electrical characteristics by the reliability test under humidity is extremely small as compared with the conventional example shown in (Table 1), and the moisture resistance can be remarkably improved.

Example 5 A predetermined number of the raw sheets A used in Example 1 were laminated for forming the lowermost layer, and an internal electrode layer made of Pd or the like was formed thereon by screen printing or the like. A and a predetermined number of internal electrode layers are alternately laminated. At this time, the internal electrode layers are printed so as to alternately face each other and reach different edges. Then, a predetermined number of the raw sheets A are laminated for forming the uppermost layer, pressed and pressed under heating to form a molded body, and cut into a predetermined shape.

Next, as the first component, SrCO_Three, CaC
O_Three, TiO_TwoTo (Sr_0.98Ca_0.02)_0.995TiO_ThreePair of
98.0 mol% as a composition ratio, as the second component
Nb _TwoO_Five0.3 mol%, and MnCO as the third component_ThreeTo
0.2 mol%, Cr_TwoO_Three0.1 mol%, as the fourth component
T SiO_TwoOf 0.6 mol%, and Na as the fifth component_TwoSiO
_ThreeWeigh 0.8 mol% and use a ball mill or the like for 40 hours
After mixing, pulverizing and drying, the mixture is air dried at 900 ° C for 2 hours.
Calcined, mixed again with a ball mill for 90 hours, pulverized
Then, apply so that the average particle diameter is 1.0 μm or less.
Agent G.

Next, a resist made of, for example, an organic resin is applied to a portion where the internal electrode layer of the molded body is exposed,
After drying at 50 ° C. for 5 minutes, the entire molded body is immersed in the coating agent G, dried at 150 ° C. for 10 minutes, and immersed in an organic solvent such as toluene to remove the resist.

Next, degreased calcining is performed in air at 800 ° C. for 4 hours, for example, in a reducing atmosphere of N ₂ : H ₂ = 9: 1.
After calcination at 50 ° C. for 4 hours, reoxidation is performed at 950 ° C. for 2 hours in air. Thereafter, an external electrode paste made of Ag or the like is applied to both end surfaces where the internal electrode layers are alternately exposed at different edges, and baked at 800 ° C. for 10 minutes in air. Then, Ni plating and solder plating are performed on the Ag electrode by, for example, an electrolytic method.

Table 5 shows the electrical characteristics and the results of the reliability test in moisture of the multilayer ceramic element thus obtained in the same manner as in Example 1.

[0054]

[Table 5]

As shown in Table 5, according to the present embodiment, the coating agent G containing a large amount of the glass component was applied to the surface of the molded product after lamination except for the end surface where the internal electrode layer was exposed. By sintering to form a ceramic coating layer, the change in electrical characteristics in a reliability test under humidity is extremely small as compared with the conventional example shown in (Table 1), and the moisture resistance can be remarkably improved.

(Example 6) First, the raw sheet A used in Example 1 is prepared. Next, the same composition as that of the raw sheet A is pulverized so that the average particle diameter becomes 0.5 μm or less, and an organic binder such as a butyral resin and an organic solvent are mixed to form a slurry. A raw sheet having a thickness of about 50 μm is prepared by a sheet forming method and cut into a predetermined size to obtain a raw sheet C.

Next, a predetermined number of the raw sheets C are laminated for the lowermost layer, and the raw sheet A is laminated thereon, and an internal electrode layer made of Pd or the like is formed by screen printing or the like.
A predetermined number of raw sheets A and internal electrode layers are alternately laminated. At this time, the internal electrode layers are printed so as to alternately face each other and reach different edges. Then, a predetermined number of the raw sheets C are laminated and formed for the uppermost layer, pressed and pressed while heating, and cut into a predetermined shape.

Next, degreased calcined at 800 ° C. for 4 hours in the air, for example, in a reducing atmosphere of N ₂ : H ₂ = 9: 1.
After calcining at 0 ° C. for 4 hours, reoxidation is performed at 950 ° C. in air for 2 hours. Thereafter, an external electrode paste made of Ag or the like is applied to both end surfaces where the internal electrode layers are alternately exposed at different edges, and baked at 800 ° C. for 10 minutes in air. Next, A
Ni plating and solder plating are applied to the g electrode by, for example, an electrolytic method.

The results of the measurement of electrical characteristics and the reliability test in wet conditions of the multilayer ceramic element thus obtained in the same manner as in Example 1 are shown in Table 6.

[0060]

[Table 6]

As shown in (Table 6), according to the present example, the uppermost layer and the lowermost layer were formed using powder having a small average particle size, and thus, compared to the conventional example shown in (Table 1). t
The an δ value is remarkably improved, and the change in the electrical characteristics by the reliability test in wet conditions is extremely small.

In the present embodiment, the entire uppermost layer and the lowermost layer are formed of the raw sheet C having a small average particle diameter. However, the raw sheet C having a small average particle diameter may be used only for a part of the uppermost layer and the lowermost layer. It was confirmed that a similar effect was obtained.

(Example 7) Raw sheet A shown in Example 1
Is previously pressurized at 100 (kg / cm ² ), and a predetermined number of sheets are laminated to form a lowermost layer. An internal electrode layer made of Pd or the like is formed thereon by screen printing or the like, and a predetermined number of unpressurized raw sheets A and internal electrode layers are alternately laminated. At this time, the internal electrode layers are printed so as to alternately face each other and reach different edges. Then, a predetermined number of the raw sheets A are laminated for the uppermost layer, and the raw sheet A is pressed and pressed at a pressure of 60 (kg / cm ² ) while heating, and cut into a predetermined shape.

Next, degreased calcining is performed in air at 800 ° C. for 4 hours, for example, in a reducing atmosphere of N ₂ : H ₂ = 9: 1.
After calcination at 50 ° C. for 4 hours, reoxidation is performed at 950 ° C. for 2 hours in air. Thereafter, an external electrode paste made of Ag or the like is applied to both end surfaces where the internal electrode layers are alternately exposed at different edges, and baked at 800 ° C. for 10 minutes in air. next,
Ni plating and solder plating are applied on the Ag electrode by, for example, an electrolytic method.

The results of the electrical property measurement and the reliability test in wet conditions of the thus obtained multilayer ceramic element as in Example 1 are shown in Table 7.

[0066]

[Table 7]

As shown in (Table 7), according to the present embodiment, the uppermost layer and the lowermost layer are formed by using a raw sheet pre-pressed at a high pressure, thereby obtaining the conventional example shown in (Table 1). Moisture resistance can be significantly improved.

It should be noted that the same effect can be obtained regardless of the pre-pressing pressure shown in this embodiment as long as it is larger than the main pressing pressure after the lamination is completed and the raw sheet does not peel off after pressing. It was confirmed.

(Embodiment 8) First, as shown in an exploded perspective view showing the laminated state of the raw sheets in FIG. 4, a predetermined number of the raw sheets A4 shown in the first embodiment were laminated and then used in the first embodiment. The raw sheets B4a are laminated, and a predetermined number of the raw sheets A4 are further laminated to form the lowermost layer. The raw sheet A4 is laminated thereon, an internal electrode layer 5 made of Pd or the like is formed by screen printing or the like, and a predetermined number of the raw sheets A4 and the internal electrode layers 5 are alternately laminated. At this time, the internal electrode layers 5 are printed so as to alternately face each other and reach different edges. Then, a predetermined number of the raw sheets A4 are stacked for the uppermost layer, a raw sheet B4b is stacked, and a predetermined number of the raw sheets A4 are further stacked. Then, it is pressurized and pressed while heating, and cut into a predetermined shape.

Next, degreased calcining is performed in air at 800 ° C. for 4 hours, for example, in a reducing atmosphere of N ₂ : H ₂ = 9: 1.
After calcination at 50 ° C. for 4 hours, reoxidation is performed at 950 ° C. for 2 hours in air. Thereafter, an external electrode paste made of Ag or the like is applied to both end surfaces where the internal electrode layers 5 are alternately exposed to different edges, and baked at 800 ° C. for 10 minutes in air. Then, Ni plating and solder plating are performed on the Ag electrode by, for example, an electrolytic method.

The results of the electrical property measurement and the reliability test in wet conditions of the multilayer ceramic element thus obtained in the same manner as in Example 1 are shown in Table 8.

[0072]

[Table 8]

As shown in (Table 8), according to this example, the raw sheets B4a and 4b containing a large amount of glass components are used to form part of the uppermost layer and the lowermost layer (Table 1).
The moisture resistance can be remarkably improved as compared with the conventional example shown in FIG.

(Embodiment 9) First, a predetermined number of the raw sheets A used in the first embodiment are laminated, then the raw sheets B used in the first embodiment are laminated, and a predetermined number of the raw sheets A are further laminated. For the bottom layer. The raw sheet A is laminated thereon, an internal electrode layer made of Pd or the like is formed by screen printing or the like, and a predetermined number of the raw sheets A and the internal electrode layers are alternately laminated. At this time, the internal electrode layers are printed so as to alternately face each other and reach different edges. And raw sheet A for the top layer
After a predetermined number of sheets are laminated, the raw sheet B is laminated, and further, a predetermined number of the raw sheets A are laminated. Then, it is pressurized and pressed while heating, and cut into a predetermined shape.

Next, degreased calcined in air at 800 ° C. for 4 hours, for example, in a reducing atmosphere of N ₂ : H ₂ = 9: 1.
After calcination at 50 ° C. for 4 hours, reoxidation is performed at 950 ° C. for 2 hours in air. Thereafter, an external electrode paste made of Ag or the like is applied to both end surfaces where the internal electrode layers are alternately exposed at different edges, and baked at 800 ° C. for 10 minutes in air.

The coating agent D used in Example 2 was applied to the surface of the uppermost layer and the lowermost layer of the sintered body thus obtained by, for example, screen printing so as not to adhere to the Ag electrode portion, and air was applied. Baking at 800 ° C. for 10 minutes. Next, Ni plating and solder plating are performed on the Ag electrode by, for example, an electrolytic method.

The results of the measurement of electrical characteristics and the reliability test in wet conditions of the thus obtained multilayer ceramic element as in Example 1 are shown in Table 9.

[0078]

[Table 9]

As shown in Table 9, according to this embodiment, the uppermost layer and a part of the lowermost layer are formed of the raw sheet B containing a large amount of glass components, and the coating material D containing a large amount of glass components is reduced and fired. By applying to the surface of the uppermost layer and the lowermost layer of the subsequent sintered body and then firing to form a ceramic coating layer, the tan δ value and the moisture resistance are significantly improved as compared with the conventional example shown in (Table 1). Can be.

Example 10 First, a sintered body provided with an Ag electrode was obtained in the same manner as in Example 9. A resist made of, for example, an organic resin is applied to the Ag electrode portion of the thus obtained sintered body, and dried at 150 ° C. for 5 minutes.
The entire sintered body is immersed in the coating material E used in Example 3, dried at 150 ° C. for 10 minutes, immersed in an organic solvent such as toluene, and the resist on the Ag electrode portion is removed.
Then, it is baked at 800 ° C. for 10 minutes in the air. Then Ag
Ni plating and solder plating are applied to the electrodes by, for example, an electrolytic method.

The results of the measurement of electrical characteristics and the reliability test in wet conditions of the multilayer ceramic element thus obtained in the same manner as in Example 1 are shown in Table 10.

[0082]

[Table 10]

As shown in (Table 10), according to this example, the uppermost layer and the lowermost layer were partially formed of the raw sheet B containing a large amount of glass components, and the coating agent E containing a large amount of glass components was formed.
Is applied to the entire surface of the sintered body after reduction firing except for the end faces where the internal electrode layers are exposed, and then fired to form a ceramic coating layer, whereby the tan δ value and moisture resistance can be significantly improved.

(Embodiment 11) First, a predetermined number of the raw sheets A used in Example 1 are stacked, then the raw sheets B used in Example 1 are stacked, and a predetermined number of the raw sheets A are further stacked. For the bottom layer. The raw sheet A is laminated thereon, and Pd
Is formed by screen printing or the like, and a predetermined number of raw sheets A and internal electrode layers are alternately laminated. At this time, the internal electrode layers are printed so as to alternately face each other and reach different edges. Then, a predetermined number of raw sheets A are stacked for the uppermost layer, and then a raw sheet B is stacked, and then a predetermined number of raw sheets A are stacked. Then, it is pressurized and pressed while heating, and cut into a predetermined shape.

The coating agent D shown in Example 2 was applied to the surfaces of the uppermost layer and the lowermost layer of the thus obtained molded article by, for example, screen printing so as not to adhere to the end face portions where the internal electrode layers were exposed. Apply at 800 ° C in air for 10
Bake for a minute.

Next, degreased calcining is performed at 800 ° C. for 4 hours in the air, for example, in a reducing atmosphere of N ₂ : H ₂ = 9: 1.
After calcination at 50 ° C. for 4 hours, reoxidation is performed at 950 ° C. for 2 hours in air. Thereafter, an external electrode paste made of Ag or the like is applied to both end surfaces where the internal electrode layers are alternately exposed at different edges, and baked at 800 ° C. for 10 minutes in air. Then, Ni plating and solder plating are performed on the Ag electrode by, for example, an electrolytic method.

The results of the measurement of electrical characteristics and the reliability test in wet conditions of the thus obtained multilayer ceramic element as in Example 1 are shown in Table 11.

[0088]

[Table 11]

As shown in Table 11, according to this example, the uppermost layer and the lowermost layer were partially formed of the raw sheet B containing a large amount of glass components, and the coating material D containing a large amount of glass components was formed.
By applying on the surface of the uppermost layer and the lowermost layer of the molded body after lamination and then firing to form a ceramic coating layer,
The moisture resistance can be remarkably improved as compared with the conventional example shown in (Table 1).

Example 12 First, a molded product was obtained in the same manner as in Example 11. A resist made of, for example, an organic resin is applied to an end surface portion of the obtained molded body where the internal electrodes are exposed, and dried at 150 ° C. for 5 minutes.
The entire molded body is immersed in the coating material E used in Example 3, dried at 150 ° C. for 10 minutes, and immersed in an organic solvent such as toluene to remove a portion of the resist for forming an external electrode.

Next, degreased calcining is performed at 800 ° C. for 4 hours in the air, for example, in a reducing atmosphere of N ₂ : H ₂ = 9: 1.
After calcination at 50 ° C. for 4 hours, reoxidation is performed at 950 ° C. for 2 hours in air. Thereafter, an external electrode paste made of Ag or the like is applied to both end surfaces where the internal electrode layers are alternately exposed at different edges, and baked at 800 ° C. for 10 minutes in air. Next, Ni plating and solder plating are performed on the Ag electrode by, for example, an electrolytic method.

The results of the measurement of electrical characteristics and the reliability test in wet conditions of the thus obtained multilayer ceramic element as in Example 1 are shown in Table 12.

[0093]

[Table 12]

As shown in (Table 12), according to this example, the uppermost layer and the lowermost layer are partially formed of the raw sheet B containing a large amount of glass components, and the coating agent E containing a large amount of glass components is formed.
Is applied to the entire surface of the molded body after lamination except for the end surfaces where the internal electrode layers are exposed, and then fired to form a ceramic coating layer, whereby tan δ is increased as compared with the conventional example shown in (Table 1).
The value and the moisture resistance can be significantly improved.

(Example 13) First, a predetermined number of the raw sheets A used in Example 1 were laminated, then the raw sheets B used in Example 1 were laminated, and a predetermined number of the raw sheets A were further laminated. For the bottom layer. The raw sheet A is laminated thereon, and Pd
Is formed by screen printing or the like, and a predetermined number of raw sheets A and internal electrode layers are alternately laminated. At this time, the internal electrode layers are printed so as to alternately face each other and reach different edges. Then, a predetermined number of the raw sheets A are stacked for the uppermost layer, a green sheet B is stacked, and a predetermined number of the raw sheets A are further stacked. Then, it is pressurized and pressed while heating, and cut into a predetermined shape.

Next, degreasing and calcining are performed in air at 800 ° C. for 4 hours, for example, in a reducing atmosphere of N ₂ : H ₂ = 9: 1.
After calcination at 50 ° C. for 4 hours, reoxidation is performed at 950 ° C. for 2 hours in air. Example 2 was applied to the side of the thus obtained sintered body.
Is applied so as not to adhere to the end face portion where the internal electrode is exposed by, for example, screen printing, and baked in air at 800 ° C. for 10 minutes. Thereafter, an external electrode paste made of Ag or the like is applied to both end surfaces where the internal electrode layers are alternately exposed at different edges, and baked at 800 ° C. for 10 minutes in air. Then, Ni plating and solder plating are performed on the Ag electrode by, for example, an electrolytic method.

The results of the electrical property measurement and the reliability test in wet conditions of the thus obtained multilayer ceramic element as in Example 1 are shown in Table 13.

[0098]

[Table 13]

As shown in (Table 13), according to this example, the uppermost layer and the lowermost layer were partially formed of the raw sheet B containing a large amount of glass components, and the coating material D containing a large amount of glass components was used.
Is applied on the side surface of the sintered body after reduction firing so as not to adhere to the end surface portion where the internal electrode is exposed, and then fired to form a ceramic coating layer, thereby preventing the adsorption of moisture from the side surface, The tan δ value and the moisture resistance can be remarkably improved as compared with the conventional example shown in Table 1).

(Example 14) First, a predetermined number of the raw sheets A used in Example 1 were laminated, then a raw sheet B used in Example 1 was laminated, and a predetermined number of the raw sheets A were further laminated. For the bottom layer. The raw sheet A is laminated thereon, and Pd
Are formed by screen printing or the like, and a predetermined number of raw sheets A and internal electrode layers are alternately laminated. At this time, the internal electrode layers are printed so as to alternately face each other and reach different edges. Then, a predetermined number of the raw sheets A are laminated thereon, and then a raw sheet B is laminated, and a predetermined number of the raw sheets A are further laminated to form the uppermost layer. And
It presses and compresses while heating and cuts it into a predetermined shape.

Example 2 was applied to the side surface of the thus obtained molded body.
Is applied by, for example, screen printing or the like so as not to adhere to the end face portion where the internal electrode layer is exposed. Next, degreased calcined at 800 ° C. for 4 hours in the air, for example, in a reducing atmosphere of N ₂ : H ₂ = 9: 1.
After calcination at 50 ° C. for 4 hours, reoxidation is performed at 950 ° C. for 2 hours in air. Thereafter, an external electrode paste made of Ag or the like is applied to both end surfaces where the internal electrode layers are alternately exposed at different edges, and baked at 800 ° C. for 10 minutes in air. Then, Ni plating and solder plating are performed on the Ag electrode by, for example, an electrolytic method.

The results of the measurement of electrical characteristics and the reliability test in wet conditions of the thus obtained multilayer ceramic element as in Example 1 are shown in Table 14.

[0103]

[Table 14]

As shown in Table 14, according to this example, the uppermost layer and the lowermost layer were partially formed of the raw sheet B containing a large amount of glass component, and the coating material D containing a large amount of glass component was used.
Is applied to the side face of the molded body after lamination so as not to adhere to the end face portion where the internal electrode layer is exposed, and then fired to form a ceramic coating layer, thereby obtaining a tan δ as compared with the conventional example shown in (Table 1). The value and the moisture resistance can be significantly improved.

In Examples 1 to 14, the composition of the ceramic powder was shown only for some combinations. However, SrTiO ₃ or a part of its Sr was replaced by Ca, M
Any composition may be used as long as the composition is mainly composed of an oxide substituted with at least one of g and Ba and has both capacitor characteristics and varistor characteristics. Although only a part of the glass component is shown,
Any material having a lower melting point than the main component may be used. Furthermore, when plating was performed on the external electrode, it was confirmed that the electrical characteristics were not deteriorated by using a glass component having acid resistance or alkali resistance enough not to be affected by the pH value of the plating solution. Further, the internal electrode layer and the external electrode may be not only a noble metal such as Pd and Ag, but also a non-metal and non-metal oxide such as Cu and Ni, or a mixture thereof.

The number of layers of the raw sheet B laminated in the middle of the uppermost layer and the lowermost layer shown in Examples 8, 9, 10, 11, 12, 13 and 14 is not limited as long as it is one or more. Absent. Further, the position at which the raw sheets B are stacked is not limited to the midpoint position in the stacking direction, and may be anywhere between the uppermost layer and the lowermost layer.

The laminated ceramic elements shown in Examples 1 to 14 each have a shape of 5.70 mm × 5.0.
The number of laminated internal electrode layers is 1 mm × 2.00 mm in the shape of a rectangular parallelepiped.
0 layer.

[0108]

As described above, according to the present invention, the laminated ceramic
The top and bottom ceramic layers of the device are
Layer is more dense than the
The porosity is reduced and moisture in the air is removed from the ceramic layer.
Because it is less likely to be absorbed or absorbed inside,
The apparent surface resistance of the ceramic layer, even if left in
The deterioration of resistance can be suppressed, and there is no deterioration of electrical characteristics
Obtaining a multilayer ceramic element with extremely excellent moisture resistance
Can be.

[Brief description of the drawings]

FIG. 1 is a sectional view of a multilayer ceramic device according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a laminated state of raw sheets in a manufacturing process of the multilayer ceramic element.

FIG. 3 is a perspective view of a multilayer ceramic element according to a second embodiment of the present invention.

FIG. 4 is an exploded perspective view showing a laminated state of raw sheets in a manufacturing process of a multilayer ceramic element according to an eighth embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 ceramic layer 1a bottom layer 1b top layer 2, 5 internal electrode layer 3, 6 external electrode 4 raw sheet A 4a, 4b raw sheet B 7 ceramic coating layer

Continuation of the front page (72) Inventor Yasuo Wakahata 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. (56) References JP-A-2-62022 (JP, A) JP-A-3-246915 (JP) JP-A-2-86110 (JP, A) JP-A-63-219115 (JP, A) JP-A-3-1516 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB (Name) H01G 4/12

Claims (5)

(57) [Claims] 1. An average particle comprising a ceramic as a main component.
A step of preparing two types of raw sheets having different diameters;
A step of laminating a plurality of raw sheets having a small average particle diameter
And a raw sheet having a large average particle diameter and an internal electrode
A step of alternately laminating a plurality of layers with an extreme layer, and
After stacking multiple sheets of raw sheet with a small average particle size, press
To form a molded body, and the molded body is placed in a reducing atmosphere.
Process of re-oxidizing after firing in an atmosphere and forming external electrodes
And manufacturing the multilayer ceramic element. 2. Lamination in a post-process mainly composed of ceramics
Pressurized with a pressure higher than the pressure used in the body making process
Of preparing two types of raw sheet and unpressurized raw sheet
And a step of laminating a plurality of the pressed raw sheets,
The non-pressurized raw sheet and the internal electrode layer are alternately placed thereon.
A step of laminating a plurality of layers, and the pressurized raw sheet
After stacking multiple sheets, press and crimp to produce a molded body
Process and firing the compact in a reducing atmosphere followed by re-acidification
Comprising a step of forming an external electrode and a step of forming an external electrode
Manufacturing method of die ceramic element. 3. A green sheet mainly composed of ceramics.
A step of laminating a plurality of sheets, on which the raw sheet and the internal
A step of alternately laminating a plurality of pole layers and
After laminating multiple sheets, press and crimp to produce a molded body
And firing the compact in a reducing atmosphere
A step of re-oxidizing, and a step of forming an external electrode,
The entire surface of the sintered body after the re-oxidation or a part thereof
Ceramics containing more glass components than
In an oxidizing atmosphere after applying a coating agent containing
Or multilayer ceramic element fired in inert atmosphere
Manufacturing method. 4. A raw sheet mainly composed of ceramics
A step of laminating a plurality of sheets, on which the raw sheet and the internal
A step of alternately laminating a plurality of pole layers and
After laminating multiple sheets, press and crimp to produce a molded body
And forming an external electrode.
All or part of the surface of the form is based on the composition of the raw sheet.
Ceramics containing many glass components
And then fired in a reducing atmosphere
Method of fabricating the multilayer ceramic element reoxidation after. 5. The step of laminating a plurality of raw sheets,
A composition that contains more glass components than the composition of the raw sheet
Laminate multiple sheets so as to sandwich the raw sheet in the middle of the raw sheet
The multilayer ceramic element according to claim 4, comprising a step of performing
Child manufacturing method.