JPH03215916A - Electrode formation method and electronic components using the same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to the formation of electrodes used in various electronic components (1) (2) The present invention relates to a method and an electronic component using the same.

Conventional technology Conventionally, conductive paints made of conductive particles, resins, solvents, and in some cases trace amounts of glass frit 1, metal oxides, and organometallic compounds have been widely used as electrode materials for various parts. It is used. Expensive precious metals such as silver, gold, platinum, and palladium are used as conductive particles, and in order to reduce the cost I of electrode materials, efforts are being made to reduce the amount of precious metals used or replace them with base metal materials. ing.

In order to reduce the amount of precious metals used, attempts have been made to use base metals as a base material and coat them with precious metals (for example, Japanese Patent Publication No. 46-40593, Japanese Patent Application Laid-Open No. 60-10).
Publication No. 0679). When a conductive paint using such noble metal coated powder is applied to a ceramic material and baked in air to form an electrode, the coated noble metal is not sintered in a continuous state and the base material is exposed. In addition, due to the generation of oxides, the conductivity decreases. In order to prevent this, the coating thickness of the precious metal must be increased, and the cost reduction effect is suppressed. In addition, in order to control the exposure of the base material, improvements have been made to plating methods when coating precious metals (for example, Japanese Patent Publication No. 61-2202
Publication No. 8).

However, with respect to powders made of base metal powder coated with noble metals, it is basically impossible to completely suppress heat diffusion from the base material to the coated metal when baking at high temperatures, so exposure of the base material is avoided. In order to control this, the thickness of the coating metal must be increased, and a significant cost reduction cannot be expected. In addition, the use of oxides such as silicon oxide, aluminum oxide, zirconium oxide, titanium dioxide, or barium titanate as the base material is also being considered (for example, Japanese Patent Publication No. 61-220
Publication No. 29, Publication No. 48586).

However, when these oxides are used, thermal diffusion into the noble metal layer is controlled compared to base metals, but since all of the above oxides are insulators, it is difficult to maintain conductivity as an electrode material. However, the coating must be thicker, and it is difficult to significantly reduce the material cost.

Copper and nickel are used for full replacement with base metal materials, and silver and copper alloys are used for partial replacement.In either case, oxides are formed when baked in air or left unattended, resulting in decreased conductivity. This requires a complicated atmosphere control process, which requires a large investment in equipment, making it difficult to significantly reduce electrode costs.

Problems to be Solved by the Invention Conductive particles made of base metal materials, or even conductive particles made of base metals or oxides coated with noble metals, have the above-mentioned structure and are subject to high-temperature oxidation due to high-temperature heat treatment or to silkiness. In order to prevent interaction with mating materials and the resulting decrease in conductivity, the thickness of the coating must be increased, which increases the amount of precious metal used and reduces the cost of conductive particles. The problem is that it has not been possible to significantly reduce

The present invention has been made in view of the above, and aims to form electrodes for various electronic components at low cost using nickel oxide, copper oxide, iron oxide, cobalt oxide, or alloys thereof.

Means for Solving the Problems In order to solve the above problems, the electrode forming method of the present invention provides a particle surface of a base metal oxide powder with a particle surface of 5.0 to 15.
It is characterized in that it is coated with 0% by weight of noble metal, fired in air, and then reduced in a hydrogen atmosphere.

The reason why the amount of coating metal is set to 5.0 to 15.0% by weight of the base material is that it is necessary to reduce the amount of precious metal used as much as possible in order to reduce costs. Here, the coating metal does not need to uniformly cover the entire base material.

In other words, it is only necessary that the diffusion of the base substance is suppressed to the extent that it does not affect the properties of the ceramic component, and if an appropriate frit is used and the sintering temperature is lowered, even 5.0% by weight may be sufficient for practical use. The effect of preventing diffusion can be obtained. On the other hand, if the amount of coating metal exceeds 15.0% by weight, the effect of reducing the amount used becomes small.

Further, there is no upper limit to the reduction temperature as long as it does not affect the electrical properties of the material fired together with the electrode.

Function: With the above-described configuration, the present invention can suppress thermal diffusion of the base metal oxide, which is the base material, during firing in air. Then, by performing hydrogen reduction, an inexpensive base metal electrode can be obtained.

In addition, there are various methods for coating precious metals on substrate materials, such as electroplating, electroless plating, thermal decomposition, and vapor deposition, but electroless plating is the most superior in terms of equipment scale and mass production. This makes it possible to produce noble metal-coated powder at low cost.

Example Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 6 Commercially available nickel oxide, steel oxide, iron oxide, and cobalt oxide powders with a particle size of 0.5 μm were immersed in an activation solution containing neutral type palladium ions, and the powders were activated. Ta. Separately, palladium chloride was dissolved in concentrated ammonia water, and hydrochloric acid was added thereto to prepare a palladium plating solution in which I) I-1 was adjusted to 8.5. Hydrazine was added to the palladium plating solution, and the activated powder was added and stirred to plate the surface of the powder with palladium. After the plating treatment, the plate was washed with water by decantation and dried to obtain a palladium-coated powder. The powder thus obtained had a weight ratio of base material to palladium of 90/10.

Next, a mixture consisting of 100 parts by weight of the above palladium-coated powder, 1.5 parts by weight of Karasu Frit, 2 parts by weight of ethyl cellulose, and 10 parts by weight of terpineol was kneaded with three rolls to form a paste, and the mixture was screen printed on an alumina substrate. Ta. As comparative samples, pastes were prepared in the same manner using powders that were not coated with palladium, and screen printed on an alumina substrate. These printed circuit boards were heated in air at 10000C for 30 minutes.
After baking for 2 minutes, hydrogen reduction was performed at 300℃ for 2 hours.
The results of measuring the electrical resistance value of the obtained thick film are shown in Table 1 below.

From Table 1, it is clear that the palladium coating has a diffusion suppressing effect.

Example 2 Activation treatment was performed by immersing nickel oxide, copper oxide, iron oxide, and cobalt oxide powder in an activation solution containing neutral type palladium ions, and a plating solution was separately prepared from platinum chloride, aqueous ammonia, and hydrochloric acid. Platinum was plated on the surface of the powder by adding radiin and the activated powder to this plating solution and stirring. After plating, it was washed with water by decantation and dried to obtain a platinum-coated powder. The weight ratio of the base material and platinum in the powder thus obtained was 90/10. Then, a conductor paste was produced in the same manner as in Example 1 using these platinum powders.

The thus obtained paste was screen printed into a desired circuit pattern on an alumina substrate and dried. Thereafter, it was baked in air at 930°C for 10 minutes, and reduced in pure hydrogen at 400°C for 2 hours.

All of the circuit pattern electrodes obtained as described above had low resistance and good solderability. This electrode could be put to practical use as a conductor electrode for hybrid integrated circuits and as a land electrode for chip components.

Example 3 Palladium-coated cobalt oxide powder 5 used in Example 2
Softening point of glass frit 1/closed 8 3 0 for g
5. Lead borosilicate glass with 'C; Owt%, ethyl cellulose as binder 71. 0 wt%
, 1.2 μl of terepinol was added as a solvent, and the mixture was thoroughly kneaded using a three-roll mill to form a paste.

On the other hand, for the resistor, particle-controlled tungsten silicide powder is made into a paste using an organic vehicle, and screen printed on an alumina substrate on which resistor electrode pads are formed using the electrode paste.

Then, after drying at 105°C for 10 minutes, 950
'C Bake in the air for 10 minutes {= I (perform J, then 2 more
Reduction was carried out in pure hydrogen for 50'C3 hours. The chip resistor thus obtained exhibited stable resistance characteristics, and by configuring the terminal electrode according to the method of the present invention, an inexpensive and high-performance chip resistor was obtained.

1 0 Example 4 Palladium-coated nickel oxide powder 5 used in Example 2
g is made into a paste using ethyl cellulose and terepinol as a binder. Next, as magnetic particles, Ni-Zn Ferrite I powder having a particle size of 1 to 3 μm is made into a paste by the above method to obtain a magnetic paste. Thereafter, the magnetic paste thus obtained and the electrode base 1 are alternately printed to form an electrode in a spiral shape. That is, the structure is such that a spiral electrode is embedded with magnetic particles.

12,000 laminates printed by the following method
After sintering in air for C2 hours, 2 20
'C was reduced in pure hydrogen for 4 hours.

It was confirmed that the inductor component thus obtained had an inductance of 100 mH.

Example 5 Palladium-coated nickel oxide powder 5 used in Example 1
Ethylce as a binder for g? Rose (45
0 cps) i. Q w t%, terepinol as a solvent], 1.0 mm was added and kneaded using three rolls to form an electrode base 1.

On the other hand, in order to process a dielectric material whose main component is BaTi○3 into Green Sea 1.1, polyvinyl butyral is added to 200 g of dielectric powder. 5 g, budil pencil phthalate 1.9 g. h Luen]. 20cc, ethanol 7
After adding 0 cc and stirring, the mixture was mixed in a ball mill for 16 hours to prepare a slurry.

Next, using the slurry IMed as above,
1. Form a film on an organic film using the cutter blade method,
A green sea 1.0 cm with a thickness of about 40 microns was obtained. Next, the paste-formed conductive particles described above were screen printed on the above processed Green Sea 1 to form an electrode pattern. Electrode-formed sheet 1 produced in the same manner
The two electrodes were laminated so that they were configured as counter electrodes with a green sheet interposed between them.

Next, this laminate was laminated by hot pressing and then cut into predetermined dimensions. This multilayer chip capacitor was held in air at 5000C for 10 hours to perform binder removal treatment. This debinding element is 125
Calcinate in air for 2 hours at 0°C, and then bake at 350°C for 4 hours.
The internal electrode was reduced in pure hydrogen for an hour. After that, metal paste 1 was applied to form the external electrode, and 60
Baking was performed in a nitrogen atmosphere at 00C. The chip capacitor thus obtained had a dielectric constant of 12,000.

Example 6 Magnesium-niobium lead oxide [Pb (Mgl/3Nb
2/3) Add 100 parts by weight of dielectric powder mainly composed of 03F, 8 parts by weight of polyvinyl butyral resin, 1.4 parts by weight of dibutyl phthalate, 40 parts by weight of trichloroethane, and 25 parts by weight of butyl acetate, and mix with a ball mill to 20 parts by weight. Kneaded for hours. The obtained dielectric slurry was formed into a sheet 1 with a thickness of 40 μm using a reverse roll method.

Next, a commercially available palladium paste is printed in a desired pattern on the dielectric sheet, and this is laminated 1 3 to produce a laminate in which electrodes and dielectrics are alternately laminated. Cut to size 1100'C-
It was baked in 2 hours. The side surface of the sintered body thus obtained where the electrode is exposed is coated with palladium produced in the same manner as in Example 1 (weight ratio of base material and palladium = 90/10). An electrode paste consisting of glass frit, ethyl cellulose, and terpineol was applied and baked at 850°C, followed by hydrogen reduction at 200°C for 2 hours. The capacitance value of the multilayer chip capacitor thus obtained is determined by the dielectric constant (ε=120
00), confirming the practicality of the palladium-coated copper oxide electrode.

The oxide powder used in this example had a particle size in the range of 0.1 to 5.0 μm, but the particle size and shape are not particularly defined.

Further, in addition to the above-mentioned embodiments, the present invention has the following advantages as described in 71, which uses gold, silver, 5-iridium, ruthenium, and alloys thereof, which can be plated electrolessly, as the coated precious metals. The electrodes are made of nickel oxide,
The oxide surface of copper oxide, iron oxide, cobalt oxide, or an alloy thereof is coated with a noble metal. Therefore, heat diffusion during firing in the air is suppressed, and it can be easily reduced, so it can be used in combination with dielectric materials, magnetic materials, resistor materials, insulator materials, etc. to create inexpensive and high-performance electronic materials. It is possible to provide parts.

Claims (4)

[Claims] (1) The particle surface of the base metal oxide powder is 5.0% of the base material.
A method for forming an electrode, comprising coating with ~15.0% by weight of a noble metal, firing in air, and reducing in a hydrogen atmosphere. (2) The method for forming an electrode according to claim 1, wherein the reduction is performed in a hydrogen atmosphere at a temperature of 200° C. or higher. (3) The base metal oxide is nickel oxide, copper oxide, iron oxide,
2. The method of forming an electrode according to claim 1, wherein the electrode is made of cobalt oxide or an alloy thereof. (4) An electronic component using the electrode obtained by the method according to claim 1.