JPH06240183A - Electrically conductive coating for electrode - Google Patents

Abstract

PURPOSE:To obtain the subject coating containing electrically conductive powder, a metal alkoxide and an organic vehicle, free from shrinkage of electrode in the sintering of a laminated capacitor and effective for preventing the agglomeration of the electrically conductive powder to prevent the deficiency of the capacitance of the capacitor. CONSTITUTION:This coating contains (A) electrically conductive powder (e.g. silver powder and copper powder), (B) a metal alkoxide (preferably zirconium alkoxide such as zirconium isopropoxide) and (C) an organic vehicle (e.g. methylcellulose and alkyd resin). The amounts of the component A and the component C are 40-85wt.% and 3-20wt.% based on total electrically conductive coating, respectively, and the amount of the component B is preferably 0.1-2 pts.wt. (in terms of metal) based on 100 pts.wt. of the component A. As the solvent for the electrically conductive coating, e.g. butylcellosolve can be used in the case of using methylcellulose as the component C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive paint for electrodes used for internal electrodes of, for example, multilayer ceramic capacitors and a conductive paint for electrodes used for other ceramics. More specifically, the present invention relates to a conductive paint for electrodes used for electrodes such as a laminated ceramic capacitor, a laminated ceramic L chip, a laminated ceramic substrate actuator, and a ceramic substrate wiring.

[0002]

2. Description of the Related Art Conventionally, when manufacturing a monolithic ceramic capacitor, there are generally a sheet method and a printing method. In any manufacturing method, dozens of layers of unfired ceramic derivative layers and internal electrode layers are alternately stacked to form a laminate, which is sintered at a high temperature, and then external electrodes are provided.

A dielectric paste prepared by mixing ceramic powder such as barium titanate, titanium oxide and lead-containing composite perovskite with an organic binder to form a slurry is used for the ceramic derivative layer of such a capacitor. To form the dielectric layer, this paste is formed into a sheet by a method such as a doctor blade method.

On the other hand, as the internal electrode material, platinum, palladium, silver, nickel, copper, or a mixture thereof,
An electrically conductive paint is used in which an electrically conductive powder such as an alloy is blended with an inorganic oxide additive as required and dispersed in an organic vehicle to form a paint.

Usually, such an electrically conductive coating material is screen-printed on the unbaked derivative sheet to form internal electrodes, a plurality of these are stacked and pressure-molded and cut into chip pieces, and then a predetermined profile is obtained. Then, it is fired to obtain an integrated capacitor body.

[0006]

When such a raw multilayer capacitor is fired, the internal electrode layers shrink more than the ceramic dielectric layers. For this reason, the internal electrode is located inside the dielectric terminal, and contact with the external terminal is insufficient, which may cause the electrode to fall off. Further, in the conventional conductive paint, the conductive powder is condensed due to sintering near the melting point of the conductive metal to reduce the electrode area, resulting in a decrease in capacity.

An object of the present invention is to provide a conductive paint which does not cause electrode pulling (contraction) during sintering of a multilayer capacitor. Another object of the present invention is to provide a heat resistant conductive paint capable of preventing the conductive powder from condensing and preventing the shortage of the capacity of the capacitor.

[0008]

The present invention provides a conductive powder,
The present invention provides a conductive coating material for electrodes, which contains a metal alkoxide and an organic vehicle.

As the conductive powder used in the conductive paint of the present invention, any known conductive powder of this kind may be used. For example, silver, platinum, gold, palladium powder,
Precious metal powder such as silver-palladium alloy ruthenium powder, nickel, copper, or alloys thereof may be used. You may use these individually or in mixture of 2 or more types. The amount of conductive powder blended is 4 with respect to the total amount of conductive paint.
It is 0 to 85% by weight. As the alkoxide, alkoxides of various metals such as zirconium, magnesium, potassium, sodium and titanium are used, and zirconium alkoxide is preferable. As the alcohol component of the metal alkoxide, alkoxides of various lower alcohols such as methanol, ethanol, n-propanol, isopropanol and butanol are used.

Specific examples of preferred metal alkoxides include tetraalkoxy zirconium, such as zirconium isopropoxide and zirconium butoxide. Further, it may be acetylated, and examples thereof include tetrakis zirconium (2,4-pentanedionato zirconium and acetylacetonato zirconium) and zirconium acetate.

The amount of the metal alkoxide compounded is preferably about 0.1 to 2.0 parts by weight in terms of metal based on 100 parts by weight of the conductive powder. When the compounding amount of the metal alkoxide is less than this, the shrinkage rate of the electrode increases. If the compounding amount is larger than this, the resistance value becomes large.

These metal alkoxides may be simply added to and mixed with the coating material, or may be used by coating the surface of the conductive powder in advance. The method of coating treatment is not particularly limited, but for example, in the dry method, the conductive powder is premixed in a mixer, and then a necessary amount of metal alkoxide is dropped and mixed to perform coating. Also,
In the wet method, the conductive powder is dispersed in water, an organic solvent, etc., and the required amount of the metal organic compound is dropped with sufficient stirring, followed by filtration and drying, or after the conductive powder is mixed and dispersed in the solution of the metal organic compound. There are methods such as filtration and drying.

There is no particular limitation on the organic vehicle used in the present invention. Well-known binder resin used for coating internal electrodes of well-known multilayer capacitors (chip capacitors), multilayer L chips, multilayer ceramic substrate actuators, etc.,
Any solvent can be used.

As the binder resin, for example, ethyl cellulose, nitrocellulose, acrylic resin, alkyd resin, saturated polyester resin, butyral resin, polyvinylpyrrolidone, etc. are used. The amount of the resin compounded is 2 to 40% by weight, preferably 3 to 20% by weight, based on the total amount of the conductive coating material.

Glass frit may be further added to these conductive paints in order to improve the adhesion.
As such a glass frit, any known glass frit such as lead borosilicate-based, bismuth borosilicate-based, lead oxide-based, bismuth oxide-based, and silicon oxide-based can be used. The paste used in the present invention may further contain various plasticizers such as dioctyl phthalate (DOP) and diethyl phthalate (DEP), or additives.

As the solvent used for the conductive paint, for example, for methyl cellulose and ethyl cellulose, a suitable solvent such as butyl cellosolve, butyl carbitol, cyclohexanone, tapinol, and butyl carbitol acetate can be used as in the conventional case.

To prepare the conductive coating material of the present invention, a resin is added to the conductive powder and then mixed and dispersed with a solvent. Alternatively, the resin and the solvent may be mixed and dispersed in the conductive powder at once.

In order to manufacture a laminated capacitor using the conductive paint of the present invention, any conventionally known method such as a sheet method and a printing method may be used. As the dielectric coating used here, a conventionally known one containing barium titanate-based, lead titanate zirconate-based, bismuth-based dielectric powder, a binder resin and a solvent may be used.

It is considered that the metal organic compound suppresses the contraction of the electrode because the metal alkoxide covers the conductive powder to improve the heat resistance and suppress the contraction.

[0020]

EXAMPLES Next, the present invention will be described more specifically based on examples.

[Example 1] The following components were mixed and dispersed using a three-roll to prepare a conductive paint by a conventional method.

Silver powder 100 parts by weight Tetraalkoxyzirconium 10 parts by weight (metal conversion: 0.5 parts by weight) Ethyl cellulose 5 parts by weight Terpineol 30 parts by weight

[Example 2] The following components were mixed and dispersed using a three-roll to prepare a conductive paint by a conventional method.

Silver-palladium powder 100 parts by weight Tetraalkoxyzirconium 10 parts by weight (metal conversion: 0.5 parts by weight) Ethylcellulose 5 parts by weight Terpineol 30 parts by weight

Comparative Example 1 A conductive coating material was prepared in the same manner as in Example 1 except that tetraalkoxyzirconium was not used.

Comparative Example 2 A conductive coating material was prepared in the same manner as in Example 2 except that tetraalkoxyzirconium was not used.

[Test Example] A PET film having a width of 10 cm and a length of 25 cm was attached to a glass plate (30 cm × 30 cm) using cellophane tape. About 8 to 10 g of each paste obtained in Examples and Comparative Examples was applied onto this PET film using an applicator. Then at 100 ℃ 12
Dry for 0 ± 15 minutes. After drying, after 2 hours or more, the electrode sheet was peeled off from the PET film and cut into a certain size. This is 8 for Example 1 and Comparative Example 1.
Firing was performed at 00 ° C., and at 850 ° C. for Example 2 and Comparative Example 2. The dimensions after firing were measured, and the shrinkage ratio was calculated by the following formula. The results are shown below.

Reduction ratio = (dimension after firing-dimension before firing) ×
100 / dimension before firing

[0029]

EFFECTS OF THE INVENTION The conventional internal electrode material shrinks more than the ceramic derivative even when the firing conditions and the like are strictly controlled, and the contact with the external electrode terminal is lost, resulting in poor contact. On the other hand, in the conductive coating material of the present invention, by using the metal alkoxide together with the conductive powder, the shrinkage of the electrode can be effectively prevented under any conditions. Further, it is possible to prevent the conductive powder from condensing and prevent the shortage of the capacity of the condenser.

Claims (4)

[Claims] 1. A conductive paint for an electrode, which contains a conductive powder, a metal alkoxide and an organic vehicle. 2. The conductive paint for an electrode according to claim 1, wherein the compounding amount of the metal alkoxide with respect to the conductive powder is 0.1 to 2.0% by weight in terms of metal. 3. The conductive paint for electrodes according to claim 1, wherein the surface of the conductive powder is covered with a metal alkoxide. 4. The conductive paint for electrodes according to claim 1, wherein the metal alkoxide is tetraalkoxyzirconium.