JPH09162452A - Ceramic element and manufacturing method thereof - Google Patents

Abstract

(57) An object of the present invention is to improve the reliability, in particular the humidity resistance property, of a ceramic element used in an electronic device or an electric device, which can be used in a bare element state. A ceramic element of the present invention has a porosity reduced by forming a thin and dense coating on the exterior of the element with a coating agent having poor wettability or a coating agent having good wettability, thereby reducing moisture content in air. Since it is less likely to adsorb and absorb the above into the inside of the ceramic layer, it is possible to suppress the deterioration of the apparent surface resistance of the ceramic layer, and it is possible to remarkably improve the moisture resistance property.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic element used in electronic equipment and electric equipment and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, semiconductor devices such as ICs and LSIs have been widely used to realize miniaturization and multi-functionality in electronic equipment and electric equipment, and along with that, general electronic parts used in electronic equipment and electric equipment. Is required to be compact and surface mountable.

In order to meet these demands, a method for reducing the size of a conventional electronic component by removing a case and resin coating and leaving only a bare element, and a method for reducing the size by stacking layers are considered. However, it is extremely difficult to configure an electronic component with only a bare element because the configuration becomes complicated and the reliability, particularly the moisture resistance characteristic, deteriorates. Therefore, in recent years, as shown in the cross-sectional view of FIG. 5, a bare element 1 is coated with a thin film of resin, glass is coated or a diffusion layer 3 is provided, and a plurality of coating layers are stacked. If the structure is porous, reliability cannot be sufficiently satisfied by either method.

[0004]

Conventionally, various methods have been developed as shown in the above-mentioned conventional example in order to secure the reliability of an electronic component composed of a bare element having a bare ceramic surface exposed. In each case, there is a problem that the configuration is complicated and the reliability is insufficient.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to obtain a highly reliable ceramic element by a relatively easy method.

[0006]

The ceramic element of the present invention achieves its initial purpose by forming a film on a ceramic surface with a coating agent having poor wettability or a coating agent having good wettability (here The so-called "wettability" means whether or not a solid, which is a ceramic surface, is wetted by a liquid coating agent when it comes into contact therewith.).

[0007]

According to the present invention, when a coating agent having poor wettability is applied to a ceramic element, the coating agent is repelled on the surface of the element and does not penetrate into the inside of the element. Can be collected to form a dense and thin film having a thickness of several μm. The formation of a dense film makes it less susceptible to the effects of outside air, especially humidity, and the thin thickness of the film makes it possible to form a homogeneous and solid film that is less prone to cracks and distortion during film formation. The reliability can be sufficiently improved even with a bare element exposed at.

Further, when a coating material having a good wettability is applied to the ceramic element, a coating is formed so as to penetrate from the surface of the element to the inside and cover the entire surface of the open pores of the porcelain, so that the porcelain itself is micro-coated from the inside. You can Further, since the thickness of the coating film formed by the coating agent having good wettability is 1 μm or less, it is possible to form a uniform and firm coating film without cracks or distortions when forming the coating film. The reliability can be sufficiently increased.

Further, when a coating material having good wettability is applied as an undercoat to the ceramic element and a coating agent having poor wettability is applied as an overcoat, a dense coating is formed on the inside and the surface of the ceramic porcelain element. The ceramic layer with a coating formed by a coating agent with good wettability serves as an intermediate layer between the coating formed by a coating agent with poor wettability and the ceramic element body, and acts as a buffer layer that relaxes the difference in thermal expansion coefficient between the two. Because it can be applied, a uniform and firm film can be formed,
It becomes more difficult to be affected by outside air, especially humidity, and the reliability can be dramatically improved.

Conversely, when a coating agent having poor wettability is applied as an undercoat to a ceramic element and a coating agent having good wettability is applied as an overcoat, a coating film having poor wettability formed on the surface of the ceramic porcelain element. Even if cracks are formed in the film, a coating can be formed so as to fill the cracks with a coating agent having good wettability, and the film is unlikely to be affected by outside air, particularly humidity, and reliability can be dramatically improved.

Further, the coating agent having poor wettability and the coating agent having good wettability begin to show effects in a state after being dried, and while being in an amorphous state, cracks and strains are less likely to occur during the formation of the coating film and are uniform. Although a solid coating can be formed, cracks and strains are likely to occur when crystallization begins, making it difficult to obtain a uniform coating.

(Embodiment 1) First, Ba is used as the first component.
CO_Three, CaCO_Three, TiO_Two(Ba_0.98Ca_0.02)
_0.995TiO_Three99.2 mol as the composition ratio of
%, Nb as the second component _TwoO_Five0.3 mol%, the third component
As MnCO_Three0.2 mol%, Cr_TwoO_Three0.1 mo
%, SiO as the fourth component_Two0.2 mol% is weighed,
After mixing for 40 h with a ball mill, crushing and drying
Calcination in air at 900 ° C for 2 hours, and then re-ball milling
After mixing for 50 hours and crushing, the average particle size becomes 1.0 μm or less.
So that Butyral tree
Slurry by mixing organic binder such as oil and organic solvent
In a sheet shape by a sheet forming method such as a doctor blade method.
Obtain a green sheet with a thickness of about 10 μm
Cut into pieces.

Next, a predetermined number of the green sheets are laminated to form an ineffective layer as the lowermost layer, and the internal electrodes 6 of FIG. 1 made of Pd or the like are formed thereon by screen printing or the like to form the green sheets. A predetermined number of internal electrodes 6 are alternately laminated. At this time, the internal electrodes 6 are printed so as to alternately face each other and reach different edges. Finally, a predetermined number of the green sheets are laminated to form an uppermost ineffective layer, which is pressed and pressed while heating and cut into a predetermined shape. Next, degreasing calcination is performed in air at 800 ° C. for 4 hours, and firing is performed in air at 1250 ° C. for 4 hours. After that, external electrode pastes made of Ag or the like are applied to both end surfaces of the internal electrodes, which are exposed at different edges alternately, and are baked in air at 800 ° C. for 10 minutes. Next, a resist made of, for example, an organic resin is applied to the external electrode 7 portion, dried at 150 ° C. for 5 minutes, and a coating agent 4 having poor wettability containing silicon atoms (Si) is applied and dried at 150 ° C. for 5 minutes. Then, it is immersed in an organic solvent such as toluene to remove the resist on the external electrode portion, and then baked at 500 ° C. for 5 minutes. Next, Ni plating and solder plating 8 are applied on the external electrodes by, for example, an electrolytic method.

The initial characteristics and reliability test results of the thus-obtained monolithic ceramic electronic component are shown in Sample Nos. 1 to 5 of Table 1. FIG. 1 is a cross-sectional view showing the structure of the monolithic ceramic electronic component of this embodiment. In FIG. 1, 4 is a film formed of a coating agent having poor wettability, 5 is a ceramic layer, 6 is an internal electrode, 7 is an external electrode, and 8 is a plated layer.

[0015]

[Table 1]

Regarding the electrical characteristics of (Table 1), the capacitance of the ceramic electronic component at 1 kHz and the voltage V _{0.1 mA} applied across the element when a current of 0.1 mA was applied to the element were Indicated. The conditions of the reliability test are 85 ° C, 85% RH, rated voltage, 10% in the case of the humidity and medium load test.
Rate of change after 00 hours, in case of temperature cycle test -20 ° C
The rate of change after 200 cycles at -85 ° C is shown. No.2
1 is a conventional example.

The shape of the monolithic ceramic electronic component shown in this embodiment is W5.70 mm × D5.00 mm × T2.
It is a 5.5 mm type of 00 mm, and the number of laminated internal electrodes is 10.

As described above, according to this embodiment, the reliability can be remarkably improved by forming a film with a coating agent having poor wettability.

(Embodiment 2) The powder having the composition shown in Embodiment 1 is mixed and pulverized for 20 hours by a ball mill or the like,
After drying, it is calcined in air at 900 ° C. for 2 hours, mixed again by a ball mill for 20 hours, pulverized and dried, and then 10 wt% of an organic binder such as PVA is added and granulated, and then the outer diameter is 10φ and the thickness is 1 t. It is molded into a disc shape. Next, degreasing calcination is performed in air at 800 ° C. for 4 hours, and firing is performed in air at 1250 ° C. for 4 hours. Then, an electrode paste made of Ag or the like is applied to both planes by, for example, screen printing and baked in air at 800 ° C. for 10 minutes. Next, a coating agent containing aluminum atoms (Al) and having good wettability is applied and baked at 600 ° C. for 5 minutes. Next, the lead wire 12 is attached with the solder 13 of FIG. 2 and the like, and the resin 11 such as epoxy is exteriorly coated.

The results of the reliability test of the ceramic electronic component thus obtained are shown in sample numbers 6 to 10 of Table 1. FIG. 2 is a sectional view of this embodiment. In FIG. 2, 2 is an electrode, 10 is a ceramic layer having a film formed of a coating agent having good wettability, and 11 is exterior coating.

As described above, according to this embodiment, the reliability can be remarkably improved by forming the film with the coating agent having good wettability.

(Embodiment 3) An electrode paste made of Ag or the like is applied to the sintered body shown in Embodiment 2 by screen printing or the like, and is baked in air at 800 ° C. for 10 minutes. Next, a coating agent having good wettability containing Al is applied and baked at 500 ° C. for 5 minutes. Apply a resist consisting of organic resin, etc. to the electrode 2 part and
After drying for a minute, a coating agent having poor wettability including Al is applied, dried at 150 ° C. for 5 minutes, immersed in an organic solvent such as Elton to remove the resist on the electrode portion, and then baked at 400 ° C. for 10 minutes. . Next, the solder 13 in FIG.
The lead wire 12 is attached by, for example.

The reliability test results of the ceramic electronic component thus obtained are shown in sample numbers 11 to 15 of (Table 1).
Shown in FIG. 3 is a sectional view of this embodiment. In FIG. 3, reference numeral 10 is a ceramic layer having a coating film formed of a coating agent having good wettability, and 4 is a coating film formed of a coating agent having poor wettability.

(Embodiment 4) An electrode paste made of Ag or the like is applied to the sintered body shown in Embodiment 2 by screen printing, for example, and is baked in air at 800 ° C. for 10 minutes. Next, a coating agent containing Si having poor wettability is applied and baked at 400 ° C. for 5 minutes. A resist made of, for example, an organic resin is applied to the electrode 2 portion of FIG.
After drying at 5 ° C for 5 minutes, a coating agent with good wettability containing Si is applied and dried at 150 ° C for 5 minutes, and the resist on the electrode portion is removed by immersing in an organic solvent such as toluene and then at 500 ° C for 30 minutes. Bake for minutes. Next, solder 13
The lead wire 12 is attached by, for example, and exterior coating is performed with resin 11 such as epoxy.

The results of the reliability test of the ceramic electronic component thus obtained are shown as sample numbers 16 to 20 in (Table 1).
Shown in FIG. 4 is a sectional view of this embodiment. In FIG. 4, 10 is a ceramic layer having a coating formed by a coating agent having poor wettability, and 4 is a coating formed by a coating agent having good wettability.

[0026]

As described above, according to the present invention, when the coating material having poor wettability is applied to the ceramic surface as in the first embodiment, the coating material is repelled by the surface of the element and penetrates into the inside of the element. Without doing so, the coating agent gathers only on the surface of the element, and a dense and thin film having a thickness of several μm can be formed. The formation of a dense film makes it less likely to be affected by outside air, especially humidity.
Since the thickness of the coating is small, cracks and strains are less likely to occur during formation of the coating, and a uniform and solid coating can be formed, and reliability can be sufficiently improved even with a bare element.

When a coating material having good wettability is applied to the ceramic surface as in the second embodiment, a film is formed so as to penetrate from the surface of the element to the inside and cover the entire surface of the open pores of the ceramic porcelain. Can be micro-coated from the inside. Further, since the thickness of the coating film formed by the coating agent having good wettability is 1 μm or less, it is possible to form a uniform and firm coating film without cracks or distortions when forming the coating film. In addition to being able to sufficiently enhance reliability, the coating film formed by the coating agent is prone to cracks and distortions in areas with large differences in coefficient of thermal expansion, such as electrode parts, so soldering is possible without the use of a resist or the like. Is possible.

Further, when a coating material having good wettability is applied as an undercoat on the ceramic surface as in the third embodiment and a coating material having poor wettability is applied as an overcoat, both the inside and the surface of the ceramic porcelain element are dense. A ceramic layer with a coating formed by a coating agent with good wettability becomes an intermediate layer between the coating formed by a coating agent with poor wettability and the ceramic body, and the difference in the coefficient of thermal expansion between them is relaxed. Since it plays the role of a buffer layer, it is possible to form a uniform and firm film, which makes it more difficult to be affected by outside air, especially humidity, and the reliability can be dramatically improved.

On the contrary, when the coating material having poor wettability is applied to the ceramic surface as the undercoat and the coating agent having good wettability is applied as the overcoat as in Embodiment 4, the coating material is formed by the coating agent having poor wettability. Even if there are defects such as cracks in the film, the film formed by the coating agent with good wettability fills those defects and a dense film is formed as a whole, which makes it difficult to be affected by outside air, especially humidity, and is reliable. It is possible to dramatically improve the sex.

Further, the coating agent having poor wettability and the coating agent having good wettability begin to show effects from the state after drying, and while being in the amorphous state, cracks and strains are less likely to occur during the formation of the film, and the coating agent is homogeneous. A firm film can be formed, but the difference in thermal expansion coefficient from other members used in electronic parts, such as metal components used in electrodes, conductive connecting members such as solder, resin components used for coating, ceramic body, etc. When the value is large, cracks and strains are likely to occur in the cooling process after the heat treatment of the coating agent. Therefore, the slower the cooling rate, the better the film without distortion can be obtained.

As described above, according to this embodiment, the reliability can be remarkably improved by applying the coating agent having good wettability or the coating agent having poor wettability. The coating agent can be prepared by methods other than the sol-gel method, alkoxide method, and coprecipitation method, but only the above method is effective as a material that can form a uniform and solid thin film with less cracks and distortion during the formation of the film. Met.

As for the components of the coating agent, only Al and Si are shown as the inorganic components, but any component having the same properties as these may be used.

The heat treatment temperature of the coating agent is most effective because cracks and strains are less likely to occur in the range where the coating agent is amorphous, but cracks and strains occur in the temperature range where crystallization of 1000 ° C. or higher begins. It was confirmed that the effect was easily diminished.

As described above, by using the coating agent having poor wettability and the coating agent having good wettability in the amorphous state, the reliability, particularly the moisture resistance property, could be remarkably improved. As described above, the present invention can obtain a sufficient effect by a simple method, and its practical effect is extremely large.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of a ceramic electronic component according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a ceramic electronic component according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a ceramic electronic component according to a fourth embodiment of the present invention.

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

[Explanation of symbols]

2 Electrode 4 Film formed by coating agent having poor wettability 10 Ceramic layer with film formed by coating agent having good wettability

Claims (22)

[Claims] 1. A ceramic element characterized in that a coating is formed on a ceramic surface with a coating agent having poor wettability. 2. The ceramic element according to claim 1, wherein the coating agent having poor wettability is produced by any one of a sol-gel method, an alkoxide method and a coprecipitation method. 3. The ceramic element according to claim 1, wherein the film formed of the coating agent having poor wettability is amorphous. 4. A coating agent having poor wettability is Si, A
2. The ceramic element according to claim 1, containing at least one of l and Ti. 5. A method of manufacturing a ceramic element, characterized in that a coating agent having poor wettability is applied to the surface of the ceramic and heat-treated at a temperature of less than 1000 ° C. 6. A method of manufacturing a ceramic element, which comprises applying a coating agent having poor wettability to a ceramic surface, heat-treating at a temperature of less than 1000 ° C., and then gradually cooling. 7. A method of manufacturing a ceramic element, characterized in that a coating agent having poor wettability is applied to the entire ceramic portion other than the electrodes. 8. A ceramic element characterized in that a film is formed on the surface of the ceramic with a coating agent having good wettability. 9. The ceramic element according to claim 8, wherein the coating agent having good wettability is produced by any one of a sol-gel method, an alkoxide method and a coprecipitation method. 10. The ceramic element according to claim 8, wherein the film formed of the coating agent having good wettability is amorphous. 11. A coating agent having good wettability is Si,
9. The ceramic element according to claim 8, containing at least one of Al and Ti. 12. A method of manufacturing a ceramic element, which comprises applying a coating agent having good wettability to a ceramic surface and heat-treating at a temperature of less than 1000.degree. 13. A method for manufacturing a ceramic element, which comprises applying a coating agent having good wettability to a ceramic surface, heat-treating at a temperature of less than 1000 ° C., and then gradually cooling. 14. A method of manufacturing a ceramic element, comprising applying a coating agent having good wettability to the entire element including an electrode. 15. A ceramic element, comprising: forming a film on a ceramic surface with a coating agent having good wettability, and then forming a film with a coating agent having poor wettability. 16. A ceramic characterized in that a coating agent having good wettability is applied to a ceramic surface and heat-treated at a temperature of less than 1000 ° C., then a coating agent having poor wettability is applied and heat-treated at a temperature of less than 1000 ° C. Device manufacturing method. 17. A coating agent having good wettability is applied to a ceramic surface, heat-treated at a temperature of less than 1000 ° C., and then gradually cooled, and a coating agent having poor wettability is applied to 1000.
A method of manufacturing a ceramic element, comprising heat-treating at a temperature lower than ° C and then gradually cooling. 18. A method of manufacturing a ceramic element, which comprises applying a coating agent having a good wettability to a ceramic surface and drying the coating material, then applying a coating agent having a poor wettability and heat-treating at a temperature of less than 1000.degree. 19. A ceramic element, comprising: forming a film on a ceramic surface with a coating agent having poor wettability, and then forming a film with a coating agent having good wettability. 20. A ceramic, characterized in that a coating agent having poor wettability is applied to a ceramic surface and heat-treated at a temperature of less than 1000 ° C., then a coating agent having good wettability is applied and heat-treated at a temperature of less than 1000 ° C. Device manufacturing method. 21. A coating agent having poor wettability is applied to a ceramic surface, heat-treated at a temperature of less than 1000 ° C., and then gradually cooled, and a coating agent having good wettability is applied to 1000.
A method of manufacturing a ceramic element, comprising heat-treating at a temperature lower than ° C and then gradually cooling. 22. A method of manufacturing a ceramic element, which comprises applying a coating agent having poor wettability to a ceramic surface, drying the coating agent, applying a coating agent having good wettability, and heat-treating at a temperature of less than 1000.degree.