JPH05243079A - Paste for external electrode of laminar ceramic capacitor, and capacitor using the same - Google Patents

Abstract

PURPOSE:To obtain a conductivity, a resistance to oxidation and an excellent matching quality with an internal electrode, by specifying atomic fractions x, y, z in a general formula of AgxCuyMz, and by specifying the concentrations of silver and copper on the surface of a grain. CONSTITUTION:Silver grains and copper grains are put into a boron nitride crucible, and they are fused in the atmosphere of a nitrogen gas by a high-frequency dielectric heating. Thereafter, the fused liquid thereof is blown out from the nozzle provided at the end of the crucible into the atmosphere of a nitrogen gas, and it is atomized. Still, the powder obtained in this manner is expressed by a general formula AgxCuyMz (where M denotes at least one element selected from among Bi, Pb and Zn, and atomic fractions x, y, z satisfy the following relations, 0.001<=x<=0.3, 0.7<=y<=0.999, 0<=z<=0.005, x+y+z=1). Further, in this Cu allay powder, the Ag concentration on the surface of its grain is not less than 2.1 times as large as the average Ag concentration of its grain, and its grain has the region wherein the Ag concentration is increased toward the surface of its grain. Thereby, the paste comprising 10 pts.wt. of this Cu alloy powder 0.1-40 pts.wt. of glass frit, and an organic vehicle can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paste for an external electrode of a laminated ceramic capacitor which is excellent in conductivity, oxidation resistance, resistance to solder erosion and excellent in matching with an internal electrode, and a laminated ceramic using the paste. It is about capacitors.

[0002]

2. Description of the Related Art Conventionally, palladium, silver or silver-palladium paste has been used as a paste for external electrodes of a monolithic ceramic capacitor. After alternately applying the external electrode paste to the laminated dielectric in which palladium, silver or silver-palladium internal electrodes are formed in multiple layers,
It has been used as an external electrode which is fired in the air at a temperature of about 600 to 900 ° C. and gives sufficient conductive contact with the internal electrode formed in multiple layers.

Silver, silver-palladium, and palladium powder are used as the conductive powder of the above-mentioned external electrode paste, but each has the following drawbacks.
Palladium is expensive and has poor conductivity. In the case of silver-palladium in which a small amount of palladium is added to silver, solderability is insufficient and it is unavoidable to plate it for use. Further, when used as an external electrode of a capacitor having a nickel internal electrode, nickel and silver do not form an alloy, so that sufficient contact cannot be obtained.

Further, when the silver external electrode paste is used, there is solder erosion, and a sufficient bond with the nickel internal electrode cannot be obtained, resulting in insufficient conductivity. There is also an attempt of an external electrode paste using copper powder, but it has to be fired in a nitrogen atmosphere, so the organic binder is poorly removed, and sufficient contact with the internal electrodes cannot be obtained.
High defective rate. When oxygen is doped and fired,
Although the binder is removed, the copper electrode is oxidized and the solderability is significantly deteriorated.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a laminated ceramic capacitor external electrode paste having excellent conductivity, oxidation resistance and matching with internal electrodes, and a capacitor using the paste.

[0006]

Means for Solving the Problems The present inventors have achieved the above object.
As a result of earnest research to achieve the present invention, the present invention has been completed.
It was That is, the present invention is as follows. 1. General formula AgxCuyMz (where M is Bi, P
at least one selected from b and Zn, and x, y, and z are original
Expressed as a child ratio, 0.001 ≦ x ≦ 0.3, 0.7 ≦ y ≦
0.999, 0 ≦ z ≦ 0.005, x + y + z = 1
It ), The silver concentration on the grain surface is
2.1 times or more, and the silver concentration increases toward the grain surface.
With respect to 100 parts by weight of the copper alloy powder having a region to be added,
Glass frit 0.1-40 parts by weight and organic vehicle
Outside the monolithic ceramic capacitor characterized by
Part electrode paste. 2. Glass frit is PbO, B₂O₃, ZnO, Si
O₂, CaO, Al₂O ₃, BaO, Bi₂O₃, Na
₂O, K₂Contain at least one selected from O and MaO
A multilayer ceramic capacitor according to claim 1,
-Paste for external electrodes. 3. Organic vehicle is ethyl cellulose, acrylic resin,
Methyl cellulose, hydroxyethyl cellulose, ethi
Le cellulose derivative, alkyd resin, butyral tree
Fat, phenol resin, alkyd phenol resin, wood
A contract characterized by containing at least one selected from rosin
The multilayer ceramic capacitor electrode electrode according to claim 1 or 2.
The most. 4. After applying the paste according to claim 1, 2 or 3, firing
Internal electrode characterized by being used as an external electrode
Is a multilayer ceramic capacitor made of nickel. 5. After applying the paste according to claim 1, 2 or 3, firing
Internal electrode characterized by being used as an external electrode
Is a laminated ceramic with palladium or silver-palladium
A condenser. 6. After applying the paste according to claim 1, 2 or 3, firing
Internal electrode characterized by being used as an external electrode
Is a multilayer ceramic capacitor made of copper.

The copper alloy powder used in the present invention is produced by an atomizing method, and the gas atomizing method is particularly preferable. The gas atomizing method already disclosed by the present inventors is more preferable (US application No. 395531).
According to the disclosure, a mixture of silver, copper, and metal species having such a composition is heated and melted by high frequency induction heating, resistance heating, or external burner heating in an inert gas atmosphere or in a vacuum. At this time, the crucible used is preferably a material that reacts with the melt having such a composition at all or only extremely slowly, and a material containing graphite, boron nitride, silicon carbide, quartz, magnesia, or a small diatom as a main component is preferable. Can be mentioned. Next, the melt is ejected from the tip of the crucible into an inert gas atmosphere. At the same time as the eruption,
This is a method in which a high-speed stream of an inert gas is jetted to the melt to make it fine. The inert gas used here means a gas that reacts with the melt having such a composition at all or only very slowly. For example, nitrogen, helium, argon, hydrogen or a mixture thereof can be used. Also,
A slight amount of impurity gas may be mixed as long as it does not affect the characteristics of the copper alloy used in the present invention. For example, the amount of oxygen in the atomized gas is preferably 2% or less, more preferably 0.5% or less. The gas pressure (before expansion) is preferably 5 kg / cm ² G or more, and 15 kg / cm ²
cm ² G or more is more preferable, and 30 kg / cm ² G or more is most preferable. The high-speed gas flow is preferably 50 m / sec or more at the gas nozzle outlet, more preferably 100 m / sec or more, and most preferably 300 m / sec. The mass velocity ratio of the gas and the melt is preferably 0.1 or more, more preferably 1 or more.

The copper alloy powder used in the present invention has the general formula Agx.
CuyMz (where M is at least one selected from Bi, Pb and Zn, 0.001 ≦ x ≦ 0.3, 0.7 ≦ y ≦
0.99 9, 0 ≦ z ≦ 0.005, x + y + z = 1,
Atomic ratio), when x is less than 0.001, sufficient oxidation resistance cannot be obtained, and when x is more than 0.3, the bondability of the internal electrodes with nickel deteriorates. Preferably 0.01 ≦ x ≦ 0.25, more preferably 0.
01 ≦ x ≦ 0.15. M is Bi, Pb, Z
Although it is one or more selected from n, solderability and adhesion can be improved. When z exceeds 0.005, the conductivity deteriorates. Preferably 0 ≦ z ≦ 0.0
005, and more preferably 0.000006 ≦ z ≦
It is 0.0005. Further, M is preferably Bi or Pb, more preferably Pb.

Further, the copper alloy powder used in the present invention has a region where the silver concentration gradually increases near the surface toward the grain surface. The silver concentration on the surface is 2.1 times or more the average silver concentration, but is preferably 3 times or more and 20 times or less, more preferably 3 times or more and 15 times or less. If it is less than 2.1, sinterability and oxidation resistance are poor. The generation mechanism of the powder having the low melting point silver concentrated on the surface, which is the characteristic of the copper alloy powder used in the present invention, has already been disclosed by the present inventors in US application 395531 as follows. Conceivable.

That is, fine metal droplets generated by collision with a high-speed airflow generated by adiabatic expansion of high-pressure gas are entrained in the high-speed airflow and rapidly cooled and solidified while traveling at high speed. It is considered that during this solidification process, a liquid phase rich in silver having a low melting point is discharged to the surface and solidifies later, resulting in a powder in which silver is concentrated on the surface. The silver concentration x of the copper alloy powder used in the present invention is Ag / (Ag + Cu + M), and the copper concentration y is Cu /
(Ag + Cu + M), M concentration z is M / (Ag + Cu +
M), atomic ratio.

Silver concentration, copper concentration on and near the surface,
The M concentration was measured by XPS (X-ray photoelectron spectroscopy analyzer). Device: XSAM800 manufactured by KRATOS, Inc. Material: A conductive double-sided tape was attached to a sample stand, and the copper alloy powder used in the present invention was adhered so as to completely cover the double-sided tape and not to deform it.

Etching conditions: Argon ion gas was accelerating voltage of 2 keV, the angle of incidence of the argon ion beam on the sample surface was 45 degrees, and the chamber pressure was 10 ^-7 torr. Measurement conditions of silver concentration: Kα ray of magnesium (voltage 12k
eV, current 10 mA) was applied, the photoelectron extraction angle was 90 ° with respect to the sample surface, and the chamber pressure was 10 ⁻⁸ torr. Silver concentration is measured, then etched,
This was repeated 5 times, and the average values of the first two measurements were used as the surface silver concentration, the surface copper concentration, and the surface M concentration.

The average silver, copper and M concentrations were measured by dissolving the sample in concentrated nitric acid and using ICP [high frequency inductively coupled plasma emission spectrometer JY38P2 manufactured by Seiko Denshi KK]. The average particle size of the powder that can be used in the present invention is 0.1 to 50 microns,
0.2 to 30 microns is preferable, and 0.2 to 1 is more preferable.
5 microns is preferred. If it exceeds 50 μm, the coating suitability and thixotropy are poor, and if it is less than 0.1 μm, the dispersibility is poor and the particles in the paste are likely to be non-uniform. The average particle diameter was measured with a laser diffraction particle diameter measuring device SALD1100 (manufactured by Shimadzu Corporation). The measurement conditions are that the powder is sufficiently dispersed using an ethylene glycol dispersion medium and the measurement is repeated 5 times.
The average value of 5 times of the volume integrated average value was defined as the average particle diameter of the powder.

The copper alloy powder used in the present invention has the general formula Ag
xCuyMz (0.001 ≦ x ≦ 0.3, 0.7 ≦ y ≦
0.999, 0 ≦ z ≦ 0.005, x + y + z = 1, where M is at least one selected from Pb, Bi, and Zn. ), But as the resistance adjusting agent, Ag, Al, S
i, Mn, Cr, Ir, Nb, Sn, Fe, Ni, H
f, Se, S, Te, In, Pd, and Rh can be mixed in a powder state or as an alloy component, and if necessary, organic copper (for example, resinate copper, copper stearate, copper oleate) can be mixed. , Copper acetate, copper laurate, copper salicylate, copper citrate, copper oxalate, copper sesquiate,
Copper octylate, copper benzoate, other copper carboxylates, copper dicarboxylates), organic platinum, organic palladium, organic zirconates, organic titanates, organic rhodium (eg acetylacetonate, palmitic acid, abietic acid, stearic acid, olein) Acid, naphthenic acid, other carboxylic acid salt, dicarboxylic acid salt) may be added to improve the adhesiveness.

The glass frit which can be used in the present invention
Melts at a specified temperature, and metal or metal
The metal external electrode and the dielectric are firmly fixed to each other.
For example, as a combination, PbO-B₂O₃-Z
nO, CaO-Al₂O₃-SiO₂, ZnO-B₂O
₃, ZnO-PbO-B₂O₃-SiO₂, PbO-S
iO₂-B₂O₃, B₂O₃-PbO, SiO₂-Zn
O-BaO, SiO₂-ZnO-MgO, SiO₂-Z
nO-CaO, SiO₂-Al₂O₃-BaO, SiO
₂-Al₂O₃-MgO, SiO₂-Al₂O₃-Ca
O, SiO₂-B₂O₃-Al₂O₃, SiO₂-B₂
O₃-Na₂O, SiO₂-B₂O₃-K₂O, SiO
₂-Na₂O, SiO₂-Li₂O, SiO₂-K
₂O, SiO ₂-B₂O₃-SrO, SiO₂-PbO
-Na₂O, SiO₂-PbO-Li ₂O, SiO₂−
PbO-K₂O, SiO₂-B₂O₃, SiO₂-Pb
O-CaO, SiO₂-ZnO, SiO₂-B₂O₃−
Bi₂O₃It is possible to use those containing as a main component. Preferably
Is zinc borosilicate, lead borosilicate, bismuth borosilicate
It is mainly composed of stainless steel.

If necessary, in order to further improve the adhesion, bismuth oxide, manganese oxide, zirconium oxide, barium oxide, beryllium oxide, cuprous oxide, tin oxide, molybdenum oxide, vanadium oxide, and oxides are added. Neodymium, cadmium oxide, iron oxide, lanthanum oxide,
Fine metal powders such as tungsten oxide, histo oxide, antimony oxide, germanium oxide, chromium oxide, lead trioxide, yttrium oxide, cerium oxide and tungsten can be added.

The softening point of the glass frit depends on the firing temperature, but is preferably 900 ° C. or lower, more preferably 300 ° C. or higher. Further, it is preferably 300 ° C. or higher and 600 ° C. or lower. As the structure of the glass frit, either crystallized glass or amorphous glass, or a mixture thereof can be used. The particle size of the glass frit is preferably 0.01 to 30 μm, more preferably 0.1 to 5 μm, in order to obtain sufficient sinterability.
The average particle diameter described here indicates the average particle diameter measured by the laser diffraction method. If it is less than 0.01 micron, agglomeration tends to occur, and if it exceeds 30 micron, the coating suitability is deteriorated.

The glass frit is used in the amount of copper alloy powder 1
0.1 to 40 parts by weight with respect to 00 parts by weight,
If it is less than 0.1, sufficient adhesiveness cannot be obtained, and
If it exceeds the weight part, the solderability becomes poor. In addition, glass enters between the external electrode and the internal electrode,
Contact cannot be made sufficiently. Preferably 0.5
To 15 parts by weight, and more preferably 0.5 to 8 parts by weight.

As the dispersant used in the present invention, the copper alloy powder, the glass frit and the necessary additives are sufficiently dispersed to give the paste having such a composition an appropriate viscosity and further improve the coating suitability. Therefore, a known organic vehicle can be used. In particular, a paste that decomposes or volatilizes below the firing temperature of the paste having such a composition is preferable. The organic vehicle means an organic binder and / or a solvent. The organic vehicle, ethyl cellulose, hydroxyethyl cellulose, methyl cellulose, nitrocellulose and ethyl cellulose derivatives,
Examples thereof include those containing acrylic resin, butyral resin, alkyd phenol resin, and wood rosin. Of these, ethyl cellulose and acrylic resin are preferable. As the acrylic resin, those having a decomposition temperature of 500 ° C. or less are preferable. Examples thereof include those containing polymethacrylic acid butyl ester, polymethacrylic acid isobutyl ester, and lower alcohol polymethacrylate. As the butyral resin, a polyvinyl butyral resin is preferable. When used in the present invention, these resins are preferably dispersed in a solvent or the like, and a known solvent can be used. However, the resin is not necessarily used and the solvent may be used as the dispersant as long as appropriate viscosity and coatability are obtained.

As the solvent, a known solvent may be used. A solvent having a small amount of volatilization during storage of the paste having such a composition, imparting an appropriate viscosity, and having excellent coating suitability is preferable. For example, terpenol, oleyl alcohol, butyl carbitol, ethyl carbitol, methyl carbitol, ethers such as ethyl cellosolve, butyl cellosolve, hexyl cellosolve, butyl carbitol acetate, ethyl carbitol acetate, methyl carbitol acetate, ethyl cellosolve acetate, Butyl cellosolve acetate, hexyl cellosolve acetate, ethyl acetate, butyl acetate, esters such as 2,2,4-trimethyl 1,3-pentanediol monoisobutyrate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, mineral spirits, toluene , And hydrocarbons such as xylene. However, it is not necessarily limited to these.

The amount of the dispersant used may be such that viscosity and conductivity are not impaired. For example, copper alloy powder 1
It is preferably 50 parts by weight to 1 part by weight with respect to 00 parts by weight. A lubricant, an antioxidant, a viscosity modifier, and an antifoaming agent (such as silicone oil) can be added to the paste of the present invention, if necessary. For example, a silane coupling agent,
Aluminum coupling agent, titanium coupling agent,
Soybean lecithin, diethanolamine, triethanolamine, tributyl phosphate, carbon number 20 to 50
Micro waxes, paraffins having 20 to 35 carbon atoms, plasticizers such as stearic acid, oleic acid, dioctyl phthalate, carboxylic acids having 20 carbon atoms, dicarboxylic acids, pyrocatechol, methylhydroquinone, hydroquinone, phenol, etc. It is also possible to add an antioxidant such as a phenol derivative or acetylacetone. Lubricants, antioxidants, viscosity modifiers, stabilizers, defoamers, etc. should be added in an amount of 2 per 100 parts by weight of the copper alloy powder.
It is preferably 0 parts by weight or less. Further, it is preferably 10 parts by weight or less.

When the paste of the present invention is used as an external electrode, it is preferable to apply it to a laminated ceramic capacitor and then fire it. The firing temperature is preferably a temperature at which the copper alloy powder and the glass frit are sufficiently sintered and combined with nickel, silver palladium, palladium or copper of the internal electrode, for example, 500 ° C to 950 ° C. 600 ° C. to 900 ° C. is preferable. The firing atmosphere is preferably an inert gas atmosphere, but at least a small amount of oxygen must be present in order to sufficiently combust and decompose the organic vehicle. The amount of oxygen added is preferably 10% or less, more preferably 1% or less, and further 1000 p
It is preferably pm or less and 1 ppm or more.

The copper alloy powder contained in the paste of the present invention has excellent oxidation resistance because it has a structure rich in silver on the surface of the powder even though it contains a small amount of silver. ing. Therefore, even during firing, it becomes possible to perform firing in a high oxygen-doped nitrogen atmosphere in the burnout region, which not only improves the yield of the product but also the conventional copper paste,
There is an advantage that it can be used as an external electrode of a monolithic ceramic capacitor having a nickel internal electrode, which cannot be achieved with a silver space.

Examples of the dielectric of the monolithic ceramic capacitor include titanic acid-based dielectrics, but the dielectrics are not limited thereto. Examples of titanic acid-based materials include barium titanate-based materials, strontium titanate-based materials, magnesium titanate-based materials, and calcium titanate-based materials.
It is considered that the fired film thus obtained also has the effects of being resistant to soldering and excellent in oxidation resistance because it is made of a stabilized alloy of copper and silver.

The characteristics of the paste of the present invention were measured with respect to the capacitance Q of the capacitor, solderability and adhesive strength.
The capacity was measured with an LCR meter (manufactured by Hioki Electric Co., Ltd.) at a frequency of 1 kHz. The solderability was measured immediately after firing and after aging in air at 150 ° C. for 2 HR after firing. The measurement was performed by dipping in a solder bath (tin / lead eutectic solder) at 230 ° C. for 10 seconds and judging from the wet area.

The adhesive strength was determined from the strength when a 0.8 mmφ tin-plated copper wire was soldered to the external electrode and pulled vertically to be peeled off.

[0027]

EXAMPLES The present invention will be specifically described below with reference to examples.

[0028]

Example 1 Silver particles (99.9% by weight or more, average particle size 2
mmφ, same as in the following examples) 5.35 g, copper particles (9
9.9 wt% or more Average particle diameter 3 mmφ, same as the following examples) 314.0075 g was put into a boron nitride crucible and heated to 1700 ° C. in a nitrogen gas atmosphere (99.9% or more) using high frequency induction heating. Dissolved. After thawing
It was jetted into a nitrogen gas atmosphere from a nozzle attached to the tip of the crucible. At the same time, 30 kg / cm ² G of nitrogen gas (99.9% or more) was jetted to the melt at a gas / liquid mass velocity ratio of 0.7 to atomize the melt. At this time, the linear velocity at the gas nozzle outlet was 150 m / sec, and the average particle size of the obtained powder was 16 μm. The silver concentration of the powder was 0.0916,0.
084, 0.070, 0.056, 0.055, the surface silver concentration is x = 0.0878, and the average silver concentration is x =
At 0.01, the surface silver concentration was 8.78 times the average silver concentration.

The average copper concentration was y = 0.99. 10 g of powder having a size of 10 microns or less in the obtained powder
And PbO-ZnO-B ₂ O ₃ glass frit 0.2 g,
Ethyl cellulose 0.002g, terpenol 0.2
g and 0.002 g of a silicon defoaming agent were sufficiently mixed to form a paste. The obtained paste was applied by DIP as an external electrode of a monolithic ceramic capacitor having nickel as an internal electrode. After coating, in a nitrogen atmosphere at 850 ° C. (burnout zone 100 ppm oxygen-doped to 55
It was baked at 0 ° C. for 10 minutes.

The capacitance of the capacitor was 330 nF, which was close to the standard value. Also, solder wetting is in the initial stage,
Both were good after aging at 150 ° C. The adhesive strength was 4 to 5 kg, which was sufficient.

[0031]

Example 2 26.945 g of silver particles, 301.5 of copper particles
9325 g, zinc particles (99.9% by weight or more) 0.03
265 g was placed in a graphite crucible and placed in a nitrogen atmosphere (99.9
% Or more) It was heated and melted to 1700 ° C. by using high frequency induction heating. The melt was jetted into a nitrogen atmosphere from a nozzle at the tip of the crucible. Simultaneously with the jetting, nitrogen gas (99.9% or more) having a gas pressure of 40 kg / cm ² G was jetted to the melt at a gas / liquid mass velocity ratio of 2.1 to atomize the melt. At this time, the gas linear velocity at the gas nozzle outlet is 160 m
/ Sec. The average particle size of the obtained powder was 14 microns. Silver concentration is 0.58, 0.4 from the grain surface
6, 0.36, 0.22, 0.1, the surface silver concentration is x =
It was 0.52 and the average silver concentration was x = 0.05. The silver concentration on the surface was 10.4 times the average silver concentration. The average copper concentration was y = 0.499, and the average zinc concentration was z = 0.0001.

Powder having a size of 10 μm or less in the obtained powder
10g and PbO-B₂O₃-SiO ₂-CaO glass
Rit 0.1g, cuprous oxide 0.001g, PbO-B
₂O ₃-BaO glass frit 0.1 g, acrylic resin
0.12 g, butyl carbitol 1 g, ethyl cellosol
1 g of syrup was thoroughly mixed to form a paste. The obtained page
Barium titanate system with nickel as internal electrode
Applied as an external electrode of a monolithic ceramic capacitor
It was After coating, bake in a nitrogen atmosphere at 900 ° C for 10 minutes
(Burnout zone 100ppm oxygen dope ~
550 ° C). After firing, the capacity of the capacitor is 310n
F, almost the same as the standard value, and soldering
The properties were good both at the initial stage and after aging at 150 ° C.

The adhesive strength was 5 kg, which was sufficient.

[0034]

Example 3 53.95 g of silver particles and 285.74 of copper particles
68 g, lead particles (99.9% by weight or more) 0.00518
g and 0.0016325 g of zinc particles were put into a boron nitride crucible and heated to 1700 ° C. in a nitrogen atmosphere by high frequency induction heating to melt. The melt was ejected from a nozzle attached to the tip of the crucible into a nitrogen gas atmosphere (99.9% or more), and at the same time as the ejection, a gas pressure of 50 kg / cm ²
Nitrogen gas of G (99.9% or more) is added to the melt as gas /
It was jetted and atomized under the condition that the liquid mass velocity was 2.3. The gas linear velocity at this time was 180 m / sec, and the average particle diameter of the obtained powder was 12 microns. Silver concentration is 0.8, 0.76, 0.66, 0.56, 0.48 from the surface
And the surface silver concentration was x = 0.785. The average silver concentration was x = 0.1, and the surface silver concentration was 7.8 times the average silver concentration. Further, the average copper concentration is y = 0.89999, and the average (lead + zinc) concentration is z =
It was 0.00001.

Among the powders obtained, powders of 5 microns or less
10g and SiO₂-B₂O₃-Na ₂O glass frit
0.1 g, bismuth oxide 0.001 g, cuprous oxide 0.1.
001 g, butyral resin 0.02 g, ethyl cellosol
Bug 1g, Butyl carbitol acetate 1g, Steari
0.0001g of copper acidate was mixed thoroughly to form a paste
The obtained paste was used as the titanate powder whose internal electrode was palladium.
External electrodes of Tronium-based monolithic ceramic capacitors
Was applied as. After coating, 800 ° C in a nitrogen atmosphere 1
Burned for 0 minutes (burnout zone 150 ppm acid
Elementary dope ~ 550 ° C).

The capacitance of the capacitor satisfied the standard value of 310 nF. The solderability was good both at the initial stage and after aging at 150 ° C. The adhesive strength was 5 kg.

[0037]

Example 4 53.9 g of silver particles and 285.74 of copper particles
g, bismuth particles (99.9% by weight or more) 0.1045
g in a boron nitride crucible, and in a nitrogen atmosphere,
It melt | dissolved by heating to 1700 degreeC using the high frequency induction heating.
The melt was jetted into the nitrogen atmosphere from the tip of the crucible. Simultaneously with the jetting, 40 kg / cm ² G of nitrogen gas containing a cylinder was atomized to the melt at a gas / liquid mass velocity ratio of 3. The gas front velocity at the nozzle outlet was 200 m / sec. The average particle size of the obtained particles was 12 microns.

The silver concentration is 0.78, 0.74, and
It was 0.66, 0.56, 0.42, and the surface silver concentration was 0.76. Also, the average silver concentration is x = 0.1,
The average copper concentration was y = 0.8999, and the average bismuth concentration was z = 0.0001. The silver concentration on the surface was 7.6 times the average silver concentration. Among the obtained powders, 10 g of powder having a particle size of 3 μm or less and PbO—Al ₂ O ₃ —B ₂ O ₃
-SrO-SiO ₂ glass frit 0.1 g, thallium oxide 0.0001 g, PbO-SiO ₂ -K ₂ O glass frit 0.1 g, ethyl cellulose 0.01 g, hexosil cellosolve 3 g, silane coupling agent 0.00
01 g was mixed thoroughly to form a paste.

The obtained paste was applied as an external electrode of a calcium titanate-based monolithic ceramic capacitor having internal electrodes of copper. After coating, 1 at 780 ℃ in nitrogen atmosphere
Heated and baked for 0 minutes (burnout zone 200pp
m oxygen doping ~ 550 ° C). The capacity of the condenser is 2
The value was 90 nF, which satisfied the standard value. Further, the solderability was good at the initial stage even after aging at 150 ° C.

The adhesive strength was 5 kg, which was sufficient.

[0041]

Example 5 21.6 g of silver particles and 50.8 g of copper particles were added.
Ron Night Ride Put in a crucible, high frequency in nitrogen atmosphere
It melt | dissolved by heating to 1700 degreeC using induction heating. Melt
Ejected from the crucible tip into the nitrogen gas atmosphere. Same as a gush
Sometimes gas pressure 20kg / cm ²Apply nitrogen gas of G to the melt
And atomized at a gas / liquid mass velocity ratio of 3. Got
The average particle size of the powder was 20 microns. The silver concentration is
0.8, 0.75, 0.6, 0.55, 0.4 from the surface
The surface silver concentration was 0.775. Also,
The average silver concentration is 0.2, the average copper concentration is 0.8, and the surface
Silver concentration was 3.8 times the average silver concentration.

Of the obtained powder, 10 g of a powder having a size of 10 μm or less, 0.1 g of ethyl cellulose, 1 g of butyl carbitol, and 0.1 g of PbO—B ₂ O ₃ —CaO glass frit were sufficiently mixed to obtain a paste. The obtained paste was applied as an external electrode of a barium titanate-based monolithic ceramic capacitor having internal electrodes made of copper,
It was baked for 10 minutes in a nitrogen atmosphere at 0 ° C.

The capacity of the capacitor was 320 nF, which satisfied the standard value. Also, the solderability was good. The adhesive strength was sufficient at 5 kg.

[0044]

Example 6 Among the powders obtained in Example 1, 10 g of powder having a size of 5 μm or less and PbO—ZnO—SiO ₂ —B ₂ O.
₃ glass frit 1g, methylcellulose 0.01g,
Hydroxyethyl cellulose 0.01g, phenol resin 0.001g, acrylic resin 0.5g, 2, 2, 4-
Trimethyl 1,3-pentanediol isobutyrate 3
g was thoroughly mixed and applied to a barium titanate-based monolithic ceramic capacitor having internal electrodes of copper by the DIP method. After coating, it was baked at 900 ° C. for 10 minutes in a nitrogen atmosphere (burnout zone 50 ppm oxygen dope).

The capacity of the obtained condenser is 400 n.
F and the standard value were obtained. Also, the solderability is 1
It was almost good even after aging at 50 ° C. The adhesive strength was 5 kg, which was sufficient.

[0046]

Example 7 10 g of powder having a particle size of 3 μm or less among the powder obtained in Example 4 and PbO—B ₂ O ₃ —SiO ₂ —ZnO
0.8 g of glass frit, 0.01 g of alkyd phenol resin, 0.1 g of acrylic resin, and 3 g of methyl cellosolve were sufficiently mixed to obtain a paste. The obtained paste was applied as an external electrode of a magnesium titanate-based monolithic ceramic capacitor having an internal electrode of nickel. After the coating, it was heated and baked in a nitrogen atmosphere at 900 ° C. for 10 minutes (burnout zone 120 ppm oxygen dope to 55
0 ° C). The obtained capacitor had a capacity of 310 nF, which was almost a standard value. The solderability is 15
It was good even after aging at 0 ° C. Adhesive strength is 4k
g was sufficient.

[0047]

[Embodiment 8] 10 g of a powder having a particle size of 10 μm or less among the powders obtained in Embodiment 3 and PbO—MgO—SiO ₂ —B ₂ O.
₃ glass frit 0.1g, ethyl cellulose 0.01
g and 3 g of ethyl cellosolve acetate were thoroughly mixed to obtain a paste. The obtained paste was applied as an external electrode of a barium titanate-based monolithic ceramic capacitor having a silver-palladium internal electrode. 850 after application
℃ It baked for 10 minutes in a nitrogen atmosphere (burnout zone 100ppm oxygen dope 550 ℃).

The obtained capacitor has a capacity of 330 n.
It was F, and the solderability was good even after the initial aging at 150 ° C. The adhesive strength was sufficient at 5 kg.

[0049]

Comparative Example 1 Commercially available copper powder (average particle size 5 microns) 10
g and PbO-ZnO-B ₂ O ₃ glass frit 0.2
g, 0.01 g of ethyl cellulose, and 1 g of terpenol were sufficiently mixed to obtain a paste. The obtained paste was applied as an external electrode of a barium titanate-based multilayer ceramic capacitor having silver-palladium as an internal electrode. After coating, it was baked in a nitrogen atmosphere at 900 ° C.

The capacity of the obtained capacitor was as small as 1 pF. The solder wettability was only about 50%.

[0051]

[Comparative Example 2] Commercially available silver powder (average particle size: 3 microns) 10
g and PbO-ZnO-B ₂ O ₃ glass frit 0.2
g, 0.01 g of ethyl cellulose, and 1 g of terpenol were sufficiently mixed to prepare a paste. The obtained paste is applied as an external electrode of a strontium titanate-based multilayer ceramic capacitor having nickel as an internal electrode, and 900
℃ Fired in a nitrogen atmosphere (burnout zone 2
00 ppm oxygen dope to 550 ° C).

The capacitance of the obtained monolithic ceramic capacitor was as small as 1 pF or less.

[0053]

Comparative Example 3 Of the powder obtained in Example 1, 10 g of a powder having a particle size of 10 μm or less, 11 g of PbO—ZnO—B ₂ O ₃ glass frit, 0.2 g of ethyl cellulose, and 2 g of oleyl alcohol were thoroughly mixed to prepare a paste. did. The obtained paste was applied as an external electrode of a magnesium titanate-based stacking ceramic capacitor having a silver-palladium internal electrode, and baked at 900 ° C. in a nitrogen atmosphere for 10 minutes.

The glass was flowing over the obtained condenser, and the capacity was too small to be measured.

[0055]

[Comparative Example 4] 10 micron of the powder obtained in Example 1
The following powder 10g and PbO-B₂O ₃Glass frit
0.0001g, acrylic resin 1g, butyl carbitol
2 g of lu acetate was thoroughly mixed to form a paste. Profit
The resulting paste is a titanate bar with nickel as the internal electrode.
As an external electrode of a lithium-based monolithic ceramic capacitor
It was applied and baked at 850 ° C. in a nitrogen atmosphere. Obtained
I tried to solder to the external electrode of the capacitor
I couldn't solder enough. Also, the adhesiveness is small
It was 0.1 kg or less.

[0056]

Comparative Example 5 194.4 g of silver particles and 12.7 g of copper particles were atomized in the same manner as in Example 1. The average particle size of the obtained powder was 11 microns. Silver concentration is x =
The copper concentration was 0.9 and y = 0.1. 1 of this powder
The following powder 10 g 0 microns and PbO-ZnO-B ₂ O
₃ glass frit 0.1g, ethyl cellulose 0.01
g and ethyl cellosolve 2 g were thoroughly mixed to obtain a paste.

The obtained paste was applied as an external electrode of a barium titanate-based multilayer ceramic capacitor having nickel as an internal electrode and baked at 900 ° C. for 10 minutes in a nitrogen atmosphere. The capacitance of the condenser was 1 nF, which was much smaller than the standard value.

[0058]

Comparative Example 6 Silver particles 26.9456 g, copper particles 301.
59325 g and zinc particles 0.03265 g were put into a graphite crucible and heated in a nitrogen atmosphere at 170 by high frequency induction heating.
It melt | dissolved by heating to 0 degreeC. The melt was jetted into the air from the tip of the crucible. Simultaneously with the jetting, air having a gas pressure of 40 kg / cm ² G was jetted to the melt at a gas / liquid mass velocity ratio of 3, and atomized. The resulting powder was amorphous and averaged 20 microns. The silver concentration was 0.0001,0.
The surface silver concentration was 0.0003, 0.001, 0.003, and 0.008, and was 0.0003. The average silver concentration is 0.
05, copper concentration 0.9499, zinc concentration 0.0001
The silver concentration on the surface was 0.006 times the average silver concentration, and the silver concentration on the surface was rather lower than the average value. Moreover, copper was oxidized.

Among the obtained powders, 10 g of powder having a particle size of 10 μm or less, 0.5 g of PbO—B ₂ O ₃ glass frit, 0.1 g of acrylic resin, and 1 g of ethyl cellosolve were thoroughly mixed. The obtained paste was applied as an external electrode of a strontium titanate-based multilayer ceramic capacitor having nickel as an internal electrode and fired at 800 ° C. in a nitrogen atmosphere. The conductivity was poor and the soldering was poor.

[0060]

INDUSTRIAL APPLICABILITY The copper paste of the present invention has good oxidation resistance, excellent solderability, and good matching with internal electrodes, and is a laminate having nickel, silver-palladium, palladium, and copper as internal electrodes, which could not be achieved in the past. It is very useful as an external electrode of a ceramic capacitor.

Claims (6)

[Claims] 1. A general formula AgxCuyMz (where M is at least one selected from Bi, Pb and Zn, and x,
y and z are represented by an atomic ratio of 0.001 ≦ x ≦ 0.3,
0.7 ≦ y ≦ 0.999, 0 ≦ z ≦ 0.005, x + y
+ Z = 1. ), The glass frit is added to 100 parts by weight of a copper alloy powder having a silver concentration of 2.1 times or more the average silver concentration on the particle surface and having a region where the silver concentration increases toward the particle surface. A paste for a multilayer ceramic capacitor external electrode, comprising 0.1 to 40 parts by weight and an organic vehicle. 2. The glass frit is made of PbO, B ₂ O ₃ , Z.
nO, SiO ₂ , CaO, Al ₂ O ₃ , BaO, Bi ₂
The paste for an external electrode of a monolithic ceramic capacitor according to claim 1, comprising at least one selected from O ₃ , Na ₂ O, K ₂ O and MgO. 3. The organic vehicle contains one or more selected from ethyl cellulose, acrylic resin, methyl cellulose, hydroxyethyl cellulose, ethyl cellulose derivative, alkyd resin, butyral resin, phenol resin, alkyd phenol resin, and wood rosin. The multilayer ceramic capacitor external electrode paste according to claim 1 or 2. 4. A multilayer ceramic capacitor in which an internal electrode is made of nickel, which is applied as an external electrode after being applied with the paste according to claim 1, 2 or 3. 5. A multilayer ceramic capacitor in which the internal electrode is made of palladium or silver-palladium, which is used as an external electrode after being applied with the paste according to claim 1, 2 or 3. 6. A multilayer ceramic capacitor in which an internal electrode is made of copper, which is used by applying the paste according to claim 1, 2 or 3 and then firing it to form an external electrode.