JP3471444B2 - Method for forming electrodes of ceramic capacitors - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode forming method for a ceramic capacitor which is widely used as an electronic component.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of electronic equipment and the high speed and high performance of ceramics, ceramic capacitors have been used in many applications such as noise filters because of their small size, large capacity and excellent high frequency characteristics.

A conventional method for forming electrodes of a ceramic capacitor will be described below. Japanese Patent Application Laid-Open No. 3-280411 discloses a method for manufacturing a surface reoxidation type semiconductor ceramic capacitor, which is characterized in that the reoxidation heat treatment on the semiconductor ceramic is performed at an oxygen partial pressure higher than the oxygen partial pressure in the atmosphere. ing. Here, an electrode forming method in which an electrode paste containing Ag is applied to a dielectric element and heat treatment is performed at a temperature of 800 ° C. is described. Generally, when forming an electrode of a ceramic capacitor, a method is used in which a dielectric element coated with an electrode paste is inserted into a ceramic container and heat-treated.

[0004]

However, in the above-mentioned conventional structure, since the ceramic container is used for the heat treatment, the surface of the electrode paste is oxidized by the oxidizing gas discharged from the container, and the static electricity of the ceramic capacitor is reduced. Coefficients of variation such as capacitance and dielectric loss increase and electrical characteristics deteriorate. Further, since the dielectric elements coated with a large number of electrode pastes are collectively heat-treated in the container, the dielectric elements coated with the electrode paste and the dielectric elements are fused to a ceramic container, There is a problem that the yield is reduced.

The present invention solves the above-mentioned conventional problems, and provides a method for forming an electrode for a ceramic capacitor, which has a small coefficient of variation of capacitance and dielectric loss, high reliability, and high process yield. With the goal.

[0006]

In order to achieve this object, an electrode forming method for a ceramic capacitor according to claim 1 of the present invention comprises an electrode paste applying step of applying an electrode paste on both surfaces of a dielectric element, Forming an electrode of a ceramic capacitor , including a heat treatment step of heat-treating the dielectric element coated with the electrode paste in the electrode paste coating step into a container made of a nickel-based alloy.
A method, wherein in the heat treatment step, the nickel
Laying an insulating spreader on a container made of a system alloy,
Spreading powder, between the dielectric elements coated with the electrode paste,
And a container composed of the dielectric element and a nickel alloy
By interposing between the electrodes of the dielectric elements,
And a container made of the dielectric element and a nickel alloy
Has a structure for preventing fusion .

According to a second aspect of the present invention, there is provided an electrode forming method for a ceramic capacitor, wherein the spreading powder is Al.
₂ O ₃ or SiO ₂ is used as the component .

According to a third aspect of the present invention, there is provided a ceramic capacitor electrode forming method according to the first and second aspects, wherein the spread powder has an average particle diameter of 50 μm or more.

[0009] electrode forming method of a ceramic capacitor according to claim 4, in claim 1, wherein the electrode paste is Ag, Zn, a structure containing at least one or more of Cu or Ni.

Here, the container made of the nickel-based alloy has a box shape, and is made of nickel-iron, nickel-copper, nickel-aluminum, nickel-manganese, nickel-chromium, nickel-. It is composed of components such as chromium-iron-copper or nickel-molybdenum. The insulating spreading powder contains Al ₂ O ₃ , SiO _{2 and the} like as components. The dielectric element is made of BaTiO ₃ , BaZr.
It contains O ₃ , CaTiO ₃ or PbTiO ₃ as a component.

[0011]

With this structure, since the container made of nickel alloy is used in the heat treatment step in the electrode formation of the ceramic capacitor, the oxidizing gas is not generated and the electrode is not oxidized, so that the coefficient of variation of capacitance and dielectric loss is reduced. Can be made smaller. In addition, by laying insulating spread powder in a container made of a nickel-based alloy and setting the average particle diameter of the spread powder to 50 μm or more, the spread powder is interposed between the dielectric elements coated with the respective electrode pastes. It is possible to prevent the electrodes from fusing together. Further, by containing at least one of Ag, Zn, Cu, or Ni in the electrode paste, it is possible to prevent reaction and fusion with the container made of the nickel alloy and the insulating spreader,
A good electrode can be formed. Further, since the container is made of a nickel-based alloy, it is not contaminated by the atmosphere during heat treatment, is resistant to rapid heating and cooling during heat treatment, and can be used semipermanently.

[0012]

EXAMPLES Hereinafter, reference examples and examples of the present invention will be described.
A description will be given with reference to the drawings.

Reference Example FIG. 1 is a sectional view of a ceramic capacitor according to a reference example of the present invention. In FIG. 1, 1 is a ceramic capacitor, 2 is a dielectric element, and 3 is an electrode formed of an electrode paste. 4 is a bonding material, and solder or a conductive adhesive is used. Reference numeral 5 denotes an exterior material which is made of an insulating material and is made of a thermosetting resin such as an epoxy resin having a weather resistance in order to prevent corrosion and deterioration of the internal dielectric element and electrodes in addition to the insulating property. 6 is a lead wire.

Here, the container made of a nickel-based alloy used in the electrode forming method of the ceramic capacitor of the present invention is
It has a box shape and is composed of nickel-chromium-iron-copper.

Next, a method of manufacturing the ceramic capacitor will be described. BaTiO ₃ , BaZrO ₃ , CaTiO
₃ , PbTiO ₃ -based powder for ceramic capacitors, binder, mold release agent, dispersant and water were weighed in the mixing ratio shown in (Table 1) and placed in a tank with a stirrer.
Mix for ~ 40 hours to form a slurry.

[0016]

[Table 1]

As the binder, water-soluble polymer-based or dispersible polymer-based binders are used, but polyvinyl alcohol-based, vinyl acetate-based, and acrylic-based binders are used here. As the release agent, a non-aqueous polymer type was mainly used.

Next, the obtained slurry was spray-dried using a spray dryer to obtain granulated particles. A molding having a diameter of 16.0 mmφ and a thickness of 2.4 mmt was obtained from the granulated particles under a pressure of 2.5 ton / cm ² . The molded body obtained here was fired at a temperature of 1390 ° C. to obtain a dielectric element.

As the next step, the method for forming the electrodes of the ceramic capacitor of the present invention will be described.

Electrode pastes to be electrodes were applied to both surfaces of the dielectric element obtained above by a screen printing method with a diameter of 12.5φ and dried at a temperature of 60 to 100 ° C. Here, in addition to Ag contained in the electrode paste, at least one Zn, Cu or Ni may be contained. The dielectric element coated with this electrode paste was placed in a container made of a nickel alloy and heat-treated at a temperature of 800 ° C. to form an electrode. As a result, the oxidation of the electrode surface could be suppressed as compared with the conventional method. Further, reaction and fusion between the container made of nickel alloy and the electrode can be prevented, and a uniform and good electrode can be formed.

Next, a lead wire was bonded to this electrode by using solder as a bonding material, and an exterior material was formed using an epoxy resin to obtain a ceramic capacitor.

The capacitance and the dielectric loss of the ceramic capacitor obtained in this reference example were measured by extracting 35 samples under the conditions of a voltage of 1 V and a frequency of 1 KHz and obtained by the conventional manufacturing technique. The results of the ceramic capacitors are shown in comparison with (Table 2).

[0023]

[Table 2]

As is clear from (Table 2), the ceramic capacitor electrode forming method of this reference example provided a ceramic capacitor having a smaller coefficient of variation in capacitance and dielectric loss than in the conventional manufacturing technique. .

( Example ) A method of manufacturing a ceramic capacitor according to an example of the present invention will be described below.

BaTiO ₃ , BaZrO ₃ , CaTiO ₃
Powder for ceramic capacitor containing as a main component, polyvinyl alcohol, and water were weighed so as to have the compounding ratio shown in (Table 3), and granulated particles were obtained by a mechanical mixing method.

[0027]

[Table 3]

The granulated particles were molded into a shape having a diameter of 16 mmφ and a thickness of 2.4 mmt by the same method as in Reference Example ,
The dielectric element was obtained by firing at a temperature of 1390 ° C.

As the next step, an embodiment of the method for forming the electrode of the ceramic capacitor of the present invention will be described.

On both sides of the obtained dielectric element, an electrode paste containing Ag serving as an electrode was applied on both sides by a screen printing method and heat treated as in the reference example . Here, the dielectric element was placed in a container made of the nickel-based alloy of this example and heat-treated at a temperature of 800 ° C. to form an electrode. The present example differs from the reference example in that the spreading powder is added in a container made of a nickel alloy. Here, a powder made of Al ₂ O ₃ was used as the spread powder having an insulating property. The average particle size of the spread powder was 50 as a result of repeated trial production.
It has been found that a thickness of at least μm, preferably at least 80 μm is desirable. It was found that when the thickness is less than 80 μm, the electrode paste and the spread powder tend to react with each other during the heat treatment or the spread powder tends to adhere to the electrode paste, which is not preferable.
As a result, the spread powder intervenes between the dielectric elements coated with the electrode paste and between the dielectric elements and the container made of the nickel-based alloy, and the electrodes of each dielectric element or the container made of the dielectric element and the nickel-based alloy become No fusion occurred and the process yield was improved.

The capacitance and the dielectric loss of the ceramic capacitor obtained in this example were measured at a voltage of 1 V, as in the reference example .
As a result of measurement under the condition of a frequency of 1 KHz, a ceramic capacitor having a smaller coefficient of variation in capacitance and dielectric loss than the conventional manufacturing technique was obtained.

In this embodiment, the single plate type high dielectric constant ceramic capacitor is used, but it can also be applied to the electrode formation of the temperature compensating ceramic capacitor, the semiconductor capacitor, and the medium and high voltage capacitors. Further, not only the single plate type but also the cylindrical type can be applied.

As described above, according to this embodiment, since the heat treatment of the electrode is performed using the container made of nickel alloy,
It is possible to obtain a ceramic capacitor having stable electric characteristics, high reliability, and high process yield.

[0034]

As described above, according to the present invention, a step of inserting a dielectric element coated with an electrode paste into a container made of a nickel-based alloy and heat-treating it, and applying A to the electrode paste
By containing at least one of g, Zn, Cu or Ni, and by laying an insulating spreader on the nickel-based container, stable electrical characteristics with a small coefficient of variation of capacitance and dielectric loss can be obtained. However, it is possible to realize an excellent method for forming electrodes of a ceramic capacitor, which can improve the process yield by preventing fusion between the dielectric elements coated with the electrode paste or between the dielectric elements and the container made of a nickel alloy.

[Brief description of drawings]

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

[Explanation of symbols]

1 Ceramic capacitor 2 Dielectric element 3 electrodes 4 Bonding material 5 Exterior materials 6 lead wire

Claims (4)

(57) [Claims] 1. An electrode paste applying step of applying an electrode paste to both surfaces of a dielectric element, and heat treatment by inserting the dielectric element coated with the electrode paste in the electrode paste applying step into a container made of a nickel-based alloy. A heat treatment step of: and a method of forming an electrode of a ceramic capacitor, comprising: in the heat treatment step, an insulating spread powder is laid in a container made of the nickel-based alloy ,
Between dielectric elements coated with electrode paste, and
It is interposed between the electric element and the container made of nickel alloy.
The electrodes of each of the dielectric elements, and the dielectric
Fusion between body element and container made of nickel alloy
A method for forming an electrode of a ceramic capacitor, which is characterized by preventing 2. The method for forming an electrode of a ceramic capacitor according to claim 1, wherein the spread powder contains Al ₂ O ₃ or SiO ₂ as its component. 3. The method for forming an electrode of a ceramic capacitor according to claim 1, wherein the average particle diameter of the spread powder is 50 μm or more. 4. The method for forming an electrode of a ceramic capacitor according to claim 1, wherein the electrode paste contains at least one of Ag, Zn, Cu and Ni.