JPH0766073A - Forming method for electrode of ceramic electronic component - Google Patents

Abstract

PURPOSE:To provide an electrode forming method for ceramic electronic components capable of diminishing the dispersion of electrode thickness, raising the yield rate and productivity, and forming electrodes with great adhering strength regardless of the kind of ceramic substrates. CONSTITUTION:The title forming method for ceramic electronic component has processes of forming a ceramic film out of an easily etchable ceramic substrate composed of a general ceramic, of etching the ceramic film formed, and of forming electrodes on the etched ceramic film by plating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming electrodes of a ceramic electronic component used in manufacturing a ceramic electronic component such as a chip capacitor and a resistor.

[0002]

2. Description of the Related Art In recent years, surface mountable ceramic electronic parts have been widely used for the purpose of downsizing electronic devices and the like, and various electrode forming methods of the ceramic electronic parts such as a metal paste coating method and a plating method are also used. Being developed.

Hereinafter, a method of forming electrodes of a ceramic electronic component by a conventional metal paste coating method will be described. A silver paste is mainly used as the metal paste, which is prepared by mixing silver powder with a glass frit, an organic binder, and a solvent. By attaching this metal paste to a ceramic substrate and heat-treating it, the glass frit in the metal paste is melted and fixed to the ceramic substrate,
Form electrodes. As a method for applying the metal paste to the ceramic substrate, the entire ceramic substrate is immersed in a metal paste bath, baked to form electrodes on the entire surface of the ceramic substrate, and then unnecessary electrode portions are cut by machining. There are two types, a method and a method of applying a metal paste only on a required portion of the surface of the ceramic substrate by screen printing or brushing and baking. Here, since the electrode thickness at this time has a large variation compared with the plating method described later, it is often applied as thick as 20 μm to 50 μm.

A conventional method for forming electrodes of a ceramic electronic component by a plating method will be described below. First, the surface of the ceramic substrate is subjected to an etching treatment in order to impart adhesion strength to the electrodes, thereby forming irregularities on the surface of the ceramic substrate. Next, an electroless plating process is performed through an intermediate layer of heavy metal to form electrodes. Alternatively, an electrode is formed by further performing electroplating after the electroless plating.
Here, the plating method includes a method of immersing the entire etched ceramic substrate in a plating bath to form an electrode on the entire surface of the ceramic substrate, and then cutting unnecessary electrode portions by machining, and a required portion of the ceramic substrate. There are two types of methods in which a resist is printed on and the electrodes are formed by plating only a predetermined portion from the beginning. The electrode thickness at this time is adjusted to 3 μm to 30 μm because the variation is smaller than that in the above-mentioned metal paste coating method.

As a method for bringing the electrodes into close contact with the ceramic substrate, the metal paste coating method produces strength by chemically reacting the glass frit with the ceramic substrate. In the plating method, the surface of the ceramic substrate is etched. A certain kind of unevenness is formed by the treatment, and the plating layer physically bites into this in the shape of an anchor to generate strength.

[0006]

However, in the above-mentioned conventional structure, the method using the metal paste coating method has a problem that a large variation occurs in the electrode thickness, the yield is lowered, and the productivity is lowered. Further, with the plating method, it is difficult to form the unevenness depending on the type of the ceramic substrate when the unevenness is formed on the surface of the ceramic substrate by the etching treatment. In the case of, even if an attempt is made to etch only a part of the surface of the ceramic base such as a grain boundary, the entire surface of the ceramic base is uniformly etched, and the uneven shape cannot be formed. Even if the plating process is performed, the plating layer cannot be caught in the ceramic substrate surface in an anchor shape,
There is a problem in that the adhesion strength of the electrode layer is reduced and the versatility is lacking.

The present invention solves the above-mentioned problems of the prior art. It is possible to eliminate variations in electrode thickness, yield is high and productivity is high, and electrodes are formed with high adhesion strength regardless of the type of ceramic substrate. It is an object of the present invention to provide a method of forming an electrode for a ceramic electronic component, which has excellent versatility.

[0008]

In order to achieve this object, an electrode forming method for a ceramic electronic component according to a first aspect of the present invention is directed to a ceramic substrate made of general ceramics rather than ceramics which is easily etched. And a step of etching the formed ceramic coating, and a step of forming an electrode on the etched ceramic coating by plating. The method for forming an electrode of a ceramic electronic component described in No. 2 includes a step of forming a ceramic film made of easily-etched ceramic on the surface of the ceramic base before the completion of sintering of the ceramic base made of general ceramics. The exposed ceramic base by etching It has a step of forming an electrode by plating on the surface, the configuration with.

Here, as the ceramics which can be easily etched, those having a multi-phase crystal phase such as barium titanate are preferably used. Further, as the etching method, general chemical etching or the like is preferably used.
As the plating method, electroless plating, a combination of electroless plating and electroplating, or the like is preferably used.

[0010]

With this configuration, even if the ceramic substrate is made of ceramics that are difficult to form irregularities on the surface by etching, the ceramics that is easy to form irregularities on the ceramic substrate by etching By forming a film, etching the ceramic film, and forming an electrode on the ceramic film by plating, the electrode layer bites into the irregularities on the ceramic film in an anchor-like manner, and the ceramic base and the ceramic Since the film and the film are chemically bonded, the electrode layer is firmly adhered to the ceramic substrate through the ceramic film, and a strong electrode can be formed regardless of the material of the ceramic substrate. Also,
By forming the electrodes by plating, it is possible to easily eliminate variations in the electrode thickness and improve the yield. Before the completion of the sintering of the ceramic substrate, a ceramic film made of ceramics that can be easily etched is formed on the ceramic substrate, and the ceramic film is completely removed by etching, and the exposed surface of the ceramic substrate is exposed. When a ceramic coating is formed on a ceramic substrate by forming electrodes by plating, two ceramic interfaces at these joints chemically interlock with each other at the crystal grain level of the ceramic, and when the ceramic coating is removed. , An uneven portion having a crystal grain size or smaller is formed on the surface of the ceramic substrate, and the electrode layer is bitten in an anchor shape there, so that the electrode can be directly formed on the ceramic substrate, and the characteristics of the ceramic electronic component can be improved. It is possible to firmly form an electrode on a ceramic substrate without degrading Kill.

[0011]

EXAMPLE 1 A method for forming an electrode of a ceramic electronic component according to a first example of the present invention will be described below with reference to the drawings. FIG. 1A is a cross-sectional view of a main part of an etching surface of ceramics, which is used for explaining an electrode forming method of a ceramic electronic component according to the first embodiment of the present invention and in which unevenness can be easily formed by etching.
FIG. 3B is a cross-sectional view of a main part of an etching surface of ceramics, which is difficult to form unevenness by etching, which is used for explaining the electrode forming method of the ceramic electronic component in the first embodiment of the present invention. 1a and 1b are ceramic crystal grains, 2
a and 2b are crystal grain boundaries indicating the boundaries between the crystal grains 1a and 1b, 3
Reference symbol a is an open crystal grain boundary that is open on the surface of the ceramics, and reference symbols A and B are etching surfaces indicating the etched surfaces.

As shown in FIG. 1A, when ceramics having a polycrystalline crystal phase or the like is subjected to an etching treatment, only the crystal grain boundaries 2a are selectively etched to open crystal grain boundaries 3a. Is formed. When the etching surface A is plated, the plating is formed so as to enclose the crystal grains near the etching surface A, and the adhesion strength of the electrode (not shown) is improved. However, as shown in FIG.
When ceramics or the like composed of a single crystal phase is subjected to an etching treatment, the crystal grains 1b and the crystal grain boundaries 2b are evenly etched and an open crystal grain crystal (not shown) is not formed. Even if it was done, the plating could not be caught inside the ceramic, and the adhesion strength of the electrode (not shown) was lowered. Therefore, a ceramic film (not shown) made of ceramics as shown in FIG. 1A is previously formed on a ceramic substrate (not shown) made of ceramics as shown in FIG. 1B, and this is etched. An electrode (not shown) is formed on the ceramic substrate (not shown) through a ceramic film (not shown) by the treatment / plating treatment.

A method of manufacturing a ceramic electronic component using the electrode forming method of the ceramic electronic component according to the first embodiment of the present invention constructed as above will be described below. First, Ti-Zr-Sn-O ceramic raw material is crushed and dried by a ball mill, and then 800 kg / cm ²
And then calcining in a furnace at 1100 ° C to 1200 ° C to produce a molded body. On the other hand, a Ba—Ti—O-based ceramic raw material powder preliminarily calcined at 1200 ° C. is crushed with an alcohol solvent in a ball mill to prepare a slurry.
Next, this slurry is applied to the surface of the molded body. Here, the coating amount of the slurry is not increased so much that the entire surface of the molded body can be covered. This is because if the coating amount is too large, there is a risk that the compact itself, which will become the ceramic substrate, and the slurry will deeply react, changing the characteristics of the ceramic substrate itself. Next, the formed body coated with the slurry is fired in a furnace at 1350 ° C. to produce a ceramic substrate having a ceramic coating. next,
The ceramic substrate is etched with an acidic ammonium fluoride solution and a nitric acid solution. Next, after pretreatment for sensitizing and activating, electroless copper plating is performed, and then electrolytic copper plating is performed to form electrodes to complete the ceramic electronic component. Here, the electrode thickness is 5 μm to 8 μm.
m.

The ceramic electronic component manufactured by the above-described method according to the first embodiment of the present invention, which uses the electrode forming method of the ceramic electronic component, and the conventional ceramic electronic component, which uses the electrode forming method of the ceramic electronic component, A performance comparison test was conducted. The results will be described below.

(Experimental Example 1) A ceramic electronic component was manufactured using the method for forming an electrode of a ceramic electronic component according to the first embodiment of the present invention, and the electrode adhesion strength was measured when the 3 mm square surface of the electrode was pulled. It was measured. The results (Table 1)
Shown in.

[0016]

[Table 1]

(Comparative Example 1) A ceramic electronic component was prepared in the same manner as in Experimental Example 1 except that the compact was fired without applying the slurry, and the electrode adhesion strength was measured. The results are shown in (Table 1).

(Comparative Example 2) A ceramic electronic component was prepared in the same manner as in Comparative Example 1 except that a molded body was prepared using Ba-Ti-O ceramic raw material, and the electrode adhesion strength was measured. The results are shown in (Table 1).

(Comparative Example 3) Ti-Zr-Sn-
A ceramic electronic product was manufactured in the same manner as in Comparative Example 2 except that the slurry containing the O-based ceramic raw material was applied and fired, and the electrode adhesion strength was measured. The results are shown in (Table 1).

As is clear from Table 1, as shown in Comparative Example 1, the Ti-Zr-Sn-O ceramics alone have a weak electrode adhesion strength, while Experimental Example 1 has Ba-T.
It can be seen that the electrode adhesion strength is equal to or higher than that of the i-O ceramics alone.

As described above, according to this embodiment, a ceramic coating is formed on the surface of the ceramic substrate, and the ceramic coating is etched and plated to make it difficult to form irregularities by etching. The electrodes can be firmly formed on the ceramic substrate.

(Embodiment 2) A method for forming electrodes of a ceramic electronic component according to a second embodiment of the present invention will be described below. When the electrode is formed on the ceramic substrate via the ceramic coating, the characteristics of the ceramic electronic component may deteriorate due to the influence of the ceramic coating. Therefore,
A ceramic coating is formed before sintering the ceramic substrate, and the ceramic coating is completely removed by etching,
By exposing the surface of the ceramic base which is uneven during the formation of the ceramic film and forming the electrode by plating on the surface, the electrode is directly adhered to the ceramic base and the characteristics of the ceramic electronic component are improved.

A method of manufacturing a ceramic electronic component using the electrode forming method of the ceramic electronic component according to the second embodiment of the present invention configured as described above will be described below. First, after crushing and drying the Ba-Ti-O ceramic raw material with a ball mill, the width is 5 mm, the inner diameter is 1 mm, and the height is 6 mm.
The coaxial molded body of 1 is prepared and fired in a furnace at 1350 ° C. to prepare a fired body. On the other hand, Ba-Ti-Nd-O based ceramic raw material powder preliminarily calcined at 1200 ° C is pulverized with a ball mill together with an alcohol solvent to which a boron based glass powder is added to prepare a slurry. Next, the slurry is applied to the surface of the fired body and refired in a furnace at 950 ° C to 1200 ° C. Next, this re-fired body is left to etch with a 5-30% solution of acidic ammonium fluoride and nitric acid for 1 to 2 hours until the ceramic film disappears. Next, after pretreatment for sensitizing and activating, electroless copper plating is performed, and then electrolytic copper plating is performed to form an electrode. Next, the electrodes are processed into a predetermined shape to produce a microwave resonator, which is one of the ceramic electronic components.

A ceramic electronic component manufactured by the above-described method according to the second embodiment of the present invention, which uses the electrode forming method for the ceramic electronic component, and a ceramic electronic component, which uses the conventional electrode forming method for the ceramic electronic component, A performance comparison test was conducted. The results will be described below.

(Experimental Example 2) A ceramic electronic component was manufactured by using the method for forming an electrode of a ceramic electronic component according to the second embodiment of the present invention, and the electrode adhesion strength when the 3 mm square surface of the electrode was pulled , Unloaded Q in microwave
The value was measured. The results are shown in (Table 2).

[0026]

[Table 2]

(Comparative Example 4) A ceramic electronic component was manufactured in the same manner as in Example 2 except that the etching time was 30 minutes, a part of the ceramic film was left and an electrode was formed on the ceramic film, and the electrode adhesion strength was measured. And the unloaded Q value was measured. The results are shown in (Table 2).

(Comparative Example 5) A ceramic electronic component was manufactured in the same manner as in Experimental Example 2 except that after the baking at 1350 ° C, the slurry was not applied and the baking was not performed again, the ceramic electronic component was manufactured and the electrode adhesion strength and The unloaded Q value was measured. The results are shown in (Table 2).

As is clear from (Table 2), Experimental Example 2
Shows that the unloaded Q is remarkably improved as compared with Comparative Example 4 in which the ceramic coating is partially left. Further, it can be seen that the electrode adhesion strength is improved as compared with Comparative Example 5 in which the electrodes are formed by direct etching. Here, Comparative Example 4 and Comparative Example 5 have different etching conditions and different surface roughness, so that the adhesion strength is greatly different.

As described above, according to this embodiment, a ceramic film is formed on a ceramic substrate, and the ceramic film is removed by etching to expose the surface of the ceramic substrate having an irregular shape when the ceramic film is formed.
By forming an electrode here by plating, the characteristics of the ceramic electronic component can be improved.

[0031]

As described above, according to the present invention, even when the ceramic substrate is made of ceramics which are difficult to form irregularities on the surface by etching, the irregularities can be formed on the ceramic substrate by etching. By forming a ceramic film made of easy ceramics, etching this ceramic film, and forming electrodes by plating on this ceramic film, the electrode layer bites into the irregularities on this ceramic film in an anchor-like manner. At the same time, since the ceramic base and the ceramic coating are chemically bonded, the electrode layer firmly adheres to the ceramic base through the ceramic coating to form a strong electrode regardless of the material of the ceramic base. It has excellent versatility and the electrode thickness can be controlled by forming the electrode by plating. It is possible to easily remove scratches, improve yield, and have excellent productivity. Before completion of sintering of this ceramic substrate, a ceramic film made of ceramics that is easy to etch is formed on the ceramic substrate. When the ceramic coating is formed on the ceramic substrate by completely removing the coating by etching and forming an electrode on the surface of the ceramic substrate exposed here by plating, two ceramic interfaces are formed at these joints. Chemically mesh with each other at the crystal grain level of ceramics, and when the ceramic coating is removed, irregularities of crystal grain size or smaller are formed on the surface of the ceramic substrate, and the electrode layer is bitten in an anchor shape there, Electrodes can be formed directly on the ceramic substrate, and the characteristics of ceramic electronic components can be improved. Excellent electrode forming method of a ceramic electronic component reliability electrodes on the ceramic substrate can be firmly formed without degrading in which can be realized.

[Brief description of drawings]

FIG. 1 (a) is a cross-sectional view of a main part of an etching surface of ceramics, which is used for explaining an electrode forming method of a ceramic electronic component in the first embodiment of the present invention and in which unevenness can be easily formed by etching. A cross-sectional view of an essential part of an etching surface of a ceramic, which is difficult to form irregularities by etching, which is used for explaining the electrode forming method of the ceramic electronic component in the first embodiment of the present invention.

[Explanation of symbols]

 1a, 1b crystal grain 2a, 2b crystal grain boundary 3a open crystal grain boundary A, B etching surface

Claims (2)

[Claims] 1. A step of forming a ceramic coating made of ceramics which is easy to etch on a ceramic substrate made of general ceramics, a step of etching the ceramic coating formed in the step, and an etching treatment in the step. And a step of forming an electrode on the formed ceramic film by plating, the method for forming an electrode of a ceramic electronic component. 2. A step of forming a ceramic coating made of ceramics which can be easily etched on the surface of the ceramic base before the completion of sintering of the ceramic base made of general ceramics, and the ceramic coating formed in the step. A method of forming an electrode of a ceramic electronic component, comprising: a step of removing by etching; and a step of forming an electrode on the surface of the ceramic substrate exposed in the step by plating.