JP2553658B2 - Electrode material for electronic parts - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrode material for electronic parts, which is made of a conductive paint containing conductive particles, a resin and a solvent.

2. Description of the Related Art Conventionally, as a method for forming electrodes of electronic parts, conductive particles, a resin, a solvent, and in some cases, a small amount of frit,
A method of applying a conductive coating material containing a metal oxide and an organometallic compound, followed by heat treatment and baking is widely used. It is desirable that the electrode have as low an electric resistance value as possible, and the commercially available conductive paint has an electric resistance value after baking of 1 × 10 ⁻² Ω · cm or less. As the conductive particles, expensive noble metals such as silver, gold, platinum, and palladium must be used to withstand heat treatment in air, but noble metals are used to reduce the cost of electrode materials. Many studies have been made to reduce the amount or replace it with a base metal material.

Copper and nickel for full replacement with base metal materials,
Although silver-copper alloy is used for partial replacement,
In both cases, oxides are formed by baking in air or leaving them, and the electric resistance value is much higher than 1 × 10 ^-2 Ω · cm, so that the function as an electrode cannot be exhibited, so the baking atmosphere is controlled and the electrode surface There is a problem in that the coating process must be performed and the manufacturing process becomes complicated.

In order to reduce the amount of noble metal used, a method of coating a base metal powder with a noble metal has been attempted (for example, JP-B-46-40593 and JP-A-60-100679).
Issue). When a conductive coating material using such a noble metal coating 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, the generation of the oxide causes the electric resistance value to become much higher than 1 × 10 ^-2 Ω · cm, resulting in a marked decrease in conductivity. In order to prevent this, the coating thickness of the noble metal must be increased, and the cost reduction effect is suppressed. Further, in order to suppress the exposure of the base material, the plating method for coating the noble metal has been improved (for example, Japanese Patent Publication No. 61-22028). However, regarding the powder in which a base metal powder is used as a base material and coated with a noble metal, it is basically impossible to completely suppress the thermal diffusion of the base material to the coating metal when baking at a high temperature, so that the exposure of the base material is prevented. In order to suppress it, it is necessary to increase the thickness of the coated precious metal, and significant cost reduction cannot be expected. Further, the use of oxides such as silicon oxide, aluminum oxide, zirconium oxide, titanium dioxide, or barium titanate as the basic substance has been studied (for example, Japanese Patent Publication No. 61-22029 and Japanese Patent Publication No. 61-48586). ). However, when an oxide is used, thermal diffusion to the noble metal layer is suppressed as compared with the base metal, but since all of the above oxides are insulators,
In order to maintain the conductivity as an electrode material at an electric resistance value of 1 × 10 ^-2 Ω · cm or less, the coating thickness must be increased, and it is difficult to significantly reduce the material cost.

DISCLOSURE OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION With respect to the conductive particles having the above-described structure and coated with a noble metal using a base metal or an oxide as a base material, in order to prevent exposure of the base material or reduction in conductivity due to baking treatment at a high temperature, However, there is a problem that the coating thickness must be increased, and thus the amount of precious metal used increases and the cost of the conductive particles cannot be significantly reduced.

The present invention has been made in view of the above points, and has an electric resistance of 1 × 10 ^-2 Ω · cm or less after baking, which is excellent in conductivity.
Moreover, it is an object of the present invention to provide an electrode material for electronic parts which is excellent in thermal stability at a low cost.

Means for Solving the Problems In order to solve the above problems, the electrode material for an electronic component of the present invention contains conductive particles and a resin and a solvent in which a particle surface of a conductive complex oxide is coated with a noble metal, and the conductivity is The composite oxide is La _1-x Sr _x CoO ₃ (0.1 _x 0.8), Pr _1-x Sr _x CoO ₃ (0.2
x0.8), Nd _1-x Sr _x CoO ₃ (0.3 _x 0.7), La _1-x Ba _x CoO
₃ (0.1 _x 0.5), Pr _1-x Ba _x CoO ₃ (0.2 _x 0.5) having one or more solid solution compositions,
Or La _2-x Sr _x CuO ₄ (0.1 _x 0.5), La _2-x Ba _x CuO ₄
One or two of (0.01 x 0.5) having a solid solution system composition, further YBa ₂ Cu ₃ O ₇ system, BiCaSrCu ₂
It is selected from those having a composition of O _5.5 system, and is characterized in that the electric resistance value after baking is 1 × 10 ⁻² Ω · cm or less.

Effect According to the present invention, since the base substance is an oxide, the diffusion to the coating noble metal layer is suppressed by the above-described structure, and therefore the base substance is exposed on the particle surface by the baking treatment at high temperature even if the coating thickness is thin. Can be suppressed. Further, since the base substance is conductive, even if it is exposed, the decrease in conductivity can be suppressed.

The reason why the composite oxide is used as the base material here is that the composite oxide is superior in conductivity and cost to the oxide containing a single metal element. In particular, La
_1-x Sr _x CoO ₅ (0.1x0.8), Pr _1-x Sr _x CoO ₃ (0.2x
0.8), Nd _1-x Sr _x CoO ₃ (0.3x0.7), La _1-x Ba _x CoO
₃ (0.1 _x 0.5), Pr _1-x Ba _x CoO ₅ (0.2 _x 0.5) having one or more solid solution compositions, or La _2-x Sr _x CuO ₄ ( 0.1x0.5), La _2-x Ba _x C
uO ₄ (0.01 x 0.5) with one or two solid solution composition, YBa ₂ Cu ₃ O ₇ system, BiCaSrC
All of the u ₂ O _5.5- based compositions have excellent conductivity, and even if the thickness of the coated precious metal is thin, a high electrical conductivity of 1 × 10 ^-2 Ω · cm or less after baking is obtained. Therefore, the cost of the conductive particles can be significantly reduced. As a method of coating the base material with the noble metal, there are an electroplating method, an electroless plating method, a thermal decomposition method, a vapor deposition method and the like, but the electroless plating method is the most excellent in terms of the scale of the apparatus and mass productivity. As a result, it becomes possible to produce the precious metal-coated powder at low cost. Examples of the noble metal that can be coated by this electroless plating method include silver, gold, platinum, palladium, rhodium, iridium, ruthenium, and alloys thereof. Further, it is possible to coat the above-mentioned two or more kinds of noble metals in a multi-layer when the noble metal is coated.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples.

(Example 1) Using La ₂ O ₃ , SrCo ₃ , and Co ₃ O ₄ as starting materials, the necessary amounts of each were weighed, mixed in ethanol for 12 hours, and dried at 900 ° C.
And calcined. The calcined powder was crushed and then baked at 1100 ° C. for 2 hours to obtain a powder having a composition of La _0.5 Sr _0.5 CoO ₃ .

On the other hand, the powder was immersed in an activating liquid containing a neutral type palladium ion, the powder was activated, and separately palladium chloride was dissolved in concentrated ammonia water, and hydrochloric acid was added thereto to adjust the pH to 8.5. A palladium plating solution was prepared. Hydrazine was added to the palladium plating solution, the activated powder was added, and the mixture was stirred to plate the surface of the powder with palladium. After this plating treatment, washing with water was performed by a decantation method, and drying was performed to obtain a palladium-coated powder. The powder La thus obtained
The weight ratio of _0.5 Sr _0.5 CoO ₃ and palladium was 70/30.

100 parts by weight of the above palladium-coated powder, 5 parts by weight of glass frit, 2 parts by weight of ethyl cellulose, terbineol
A mixture consisting of 10 parts by weight is kneaded with a three-roll to form a paste, which is screen-printed on an alumina substrate and then 1000 ° C.
It was baked for 10 minutes. The thick film thus baked had an electric resistance value of 4 × 10 ⁻³ Ω · cm and showed excellent conductivity.

On the other hand, in the case of a thick film formed on the alumina substrate by the same method as above using powder that does not have palladium coating on La _0.5 Sr _0.5 CoO _3, it shows a resistance value of 7 to 9 × 10 ^-2 Ω · cm. The resistance value remarkably increased as compared with the case where the palladium-coated powder was baked. This is because the boundary between the baked thick film and the alumina substrate is colored blue, so La _0.5 Sr _0.5 Co
It is considered that the resistance value increases due to the reaction of O ₃ with alumina. Therefore, the palladium coating enhances the conductivity of the powder and at the same time is the base material.
It is considered that the two effects of suppressing the reaction between La _0.5 Sr _0.5 CoO ₃ and the substrate material are combined to form a thick film having excellent conductivity on the alumina substrate.

Further, the same experiment as above was performed by changing the thickness of the palladium coating, but the weight ratio of La _0.5 Sr _0.5 CoO ₃ and palladium was changed.
Even in the case of 80/20, excellent conductivity equivalent to the above was confirmed, and it became clear that the amount of precious metal used could be significantly reduced.

(Example 2) La _1-x Sr _x was prepared in the same manner as in Example 1 using La ₂ O ₃ , Pr ₆ O ₁₁ , Nd ₂ O ₃ , BaCo ₃ , SrCo ₃ and Co ₃ O ₄ as starting materials. CoO ₃ , Pr
_1-x Sr _x CoO ₃ , Nd _1-x Sr _x CoO ₃ , La _1-x Ba _x CoO ₃ , Pr _1-x Ba _x CoO ₃
Powders with different x of each composition system were prepared. Using these powders as a base material, a plating treatment was performed in the same manner as in Example 1 to obtain a palladium-coated powder having a base material / palladium weight ratio of 70/30. Using this powder, a conductor paste was prepared in the same manner as in Example 1 and baked on an alumina substrate to measure the electric resistance value. The results obtained by converting the measured values into Ω · cm are shown in Table 1 below.

From the results in Table 1 above, it can be seen that the electrical resistance of the baked thick film is not determined solely by the coated palladium, but is influenced by the composition of the substrate material. In order to obtain excellent conductivity, the composition of the substrate material should be La _1-x Sr _x CoO ₃ (0.1 _x 0.8), Pr _1-x Sr _x CoO ₃ (0.2
x0.8), Nd _1-x Sr _x CoO ₃ (0.3x0.7), La _1-x Ba _x C
OO ₃ (0.1 _x 0.5), Pr _1-x Ba _x CoO ₃ (0.2 _x 0.5) are suitable.

Next, using an oxide obtained by compounding the above materials as a substrate substance, palladium plating, pasting and baking were performed in the same manner as above, and the electrical resistance value of the obtained thick film was measured. As shown in, excellent conductivity was confirmed.

Example 3 Using La ₂ O ₃ , SrCO ₃ , BaCO ₃ and CuO as starting materials, the necessary amounts of each were weighed and mixed in ethanol for 12 hours, dried and then 90
After firing at 0 ℃ for 12 hours, heat treatment in oxygen at 600 ℃
Powders having different compositions of x of _2-x Sr _x CuO ₄ and La _2-x Ba _x CuO ₄ were obtained.

On the other hand, the above-mentioned powder is immersed in an activation solution containing a neutral type palladium ion for activation treatment, and a plating solution composed of platinum chloride, ammonia water and hydrochloric acid is separately prepared, and this plating solution is activated with hydrazine. The treated powder was added and the surface of the powder was plated with platinum by stirring. After this plating treatment, washing with water was performed by a decantation method to obtain a dried platinum-coated powder. The weight ratio of the thus obtained powder substrate material to platinum was 70/30.

Using the platinum-coated powder, a conductor paste was prepared in the same manner as in Example 1, baked on an alumina substrate at a temperature of 900 ° C., and the electric resistance value was measured. This measured value is Ω
-The results of unit conversion into cm are shown in Table 3 below.

From the results in Table 3 above, in order to obtain excellent conductivity,
The composition of the basic substance is La _2-x Sr _x CuO ₄ (0.1x0.
5), La _2-x Ba _x CuO ₄ (0.01 _x 0.5) is suitable.

Next, using an oxide obtained by compounding the above materials as a substrate substance, platinum plating, pasting and baking were performed in the same manner as above, and the electrical resistance value of the thick film thus obtained was measured. As shown in Table 4, excellent conductivity was confirmed.

Example 4 Using Y ₂ O ₃ , BaCO ₃ , CuO, Bi ₂ O ₃ , CaCO ₃ , and SrCO ₃ as starting materials, the necessary amounts of each were weighed, mixed in ethanol for 12 hours, dried, and then dried at 850 ° C. After firing for 12 hours at 600 ° C., heat treatment was performed in oxygen to obtain a powder having a composition of YBa ₂ Cu ₃ O ₇ and BiCaSrCu ₂ O _5.5 .

On the other hand, the activation treatment is performed by immersing the above powder in an activation solution containing a neutral type palladium ion, and a plating solution consisting of 4C Na salt of gold cyanide and ethylenediaminetetraacetic acid (EDTA) and hydrochloric acid is separately prepared, Sodium ascorbate and activation-treated powder were added to this plating solution, and the surface of the powder was plated with gold by stirring. After this plating treatment, washing with water was carried out by a decantation method and drying to obtain a gold-coated powder. The powder thus obtained had a weight ratio of substrate substance to gold of 60/40.

Then, using the above gold-coated powder, a conductor paste was prepared in the same manner as in Example 1, and the conductor paste was formed on the alumina substrate.
It baked at 0 degreeC and measured the electrical resistance value. As a result, the electric resistance value when the substrate material is YBa ₂ Cu ₃ O ₇ is 6 × 10 ⁻³ Ω · cm,
In the case of BiCaSrCu ₂ O _5.5 , it was 8 × 10 ⁻³ Ω · cm, confirming excellent conductivity.

(Example 5) 100 parts by weight of dielectric powder containing lead magnesium niobate [Pb (Mg _1/3 Nb _2/3 ) O ₃ ] as a main component, 8 parts by weight of polyvinyl butyral resin, 4 parts by weight of dibutyl phthalate, Add 40 parts by weight of trichloroethane and 25 parts by weight of butyl acidate,
Kneaded in a ball mill for 20 hours. The derivative slurry thus obtained was formed into a sheet with a thickness of 40 μm by the reverse roll method.

Next, in the same manner as in Example 1, La _0.5 Sr _0.5 CoO ₃
Powder whose surface is coated with palladium (La _0.5 Sr _0.5 CoO ₃
And a weight ratio of palladium to 50/50) were prepared, ethyl cellulose and terpineol were added thereto, and the mixture was kneaded with a three-roll mill to prepare an electrode paste. This electrode paste is printed in a desired pattern on the dielectric sheet, and by laminating this, a laminated body in which electrodes and dielectrics are alternately laminated is produced, and then cut into desired dimensions 1100. It was baked at ℃ for 2 hours. On the side of the sintered body thus obtained where the electrodes were exposed, palladium-coated La _0.5 Sr _0.5 CoO ₃ (La _0.5 Sr _0.5 CoO ₃ and palladium weight ratio produced in the same manner as in Example 1) was used. / 30) and glass frit, ethyl cellulose, and terpineol
It was baked at 800 ° C. The capacitance value of the multilayer chip capacitor obtained in this way is determined by the dielectric constant (ε to 1200) of the dielectric.
It is in good agreement with the design value calculated from (1), and the practicality of the electrode using La _0.5 Sr _0.5 CoO ₃ coated with palladium was confirmed.

In addition to the present embodiment, the conductive complex oxide particles coated with a noble metal may be used for chip resistors, chip inductors, varistors,
It goes without saying that the piezoelectric element has practical utility as an electrode for a ceramic multilayer wiring board or the like.

Since the composite oxides targeted by the present invention usually have oxygen defects, the composition of oxygen is not particularly specified. Further, in order to control the chemical stability or electrical characteristics of the base substance, a metal element other than the main component element or an anion element may be added to the base substance. Further, the composite oxide powder used in the above examples,
Although it had a particle diameter in the range of 5.0 to 0.1 μm, there is no particular limitation on the particle diameter and particle shape.

On the other hand, it goes without saying that silver, rhodium, iridium, ruthenium and alloys thereof capable of electroless plating may be used as the coating noble metal in addition to the above-mentioned examples.

EFFECTS OF THE INVENTION As described above, the electrode material for electronic parts of the present invention comprises conductive particles in which the particle surface of the conductive composite oxide is coated with a noble metal, a resin, and a solvent, and the conductive composite oxide is La. _1-x S
r _x CoO ₃ (0.1 _x 0.8), Pr _1-x Sr _x CoO ₃ (0.2 _x 0.
8), Nd _1-x Sr _x CoO ₃ (0.3 _x 0.7), La _1-x Ba _x CoO ₃ (0.1
x0.5), Pr _1-x Ba _x CoO ₃ (0.2 _x 0.5) 1
Or two or more solid solution compositions, or La _2-x Sr _x CuO ₄ (0.1 _x 0.5), La _2-x Ba _x CuO ₄ (0.0
1 x 0.5) having one or two solid solution compositions, and YBa ₂ Cu ₃ O ₇ and BiCaSrCu ₂ O _5.5 compositions. Since the electric resistance value after baking is 1 × 10 ^-2 Ω · cm or less, high conductivity can be obtained even if the thickness of the coated precious metal is thin, so the cost of the conductive particles is significantly reduced. be able to. Therefore, it is possible to inexpensively provide an electrode material for electronic parts, which has an electric resistance value after baking of 1 × 10 ^-2 Ω · cm and which has excellent conductivity and thermal and chemical stability, and various ceramics. Since it shows excellent conductivity even when baked on and does not impair the electrical characteristics of ceramics, it can be used as an electrode material for various electronic components such as alumina wiring boards, chip capacitors, chip resistors, chip inductors, varistors, and piezoelectric elements. The practical value is enormous.

 ─────────────────────────────────────────────────── --Continued from the front page (56) Reference JP-A-58-178903 (JP, A) JP-A-62-254494 (JP, A) JP-A-58-68918 (JP, A) JP-A-63- 207007 (JP, A) JP 63-190712 (JP, A) JP 51-150692 (JP, A) JP 55-71667 (JP, A)

Claims (1)

(57) [Claims] 1. A conductive complex oxide comprising conductive particles having a particle surface coated with a noble metal, a resin and a solvent, wherein the conductive complex oxide is La _1-x Sr _x CoO ₃ (0.1 _× 0.8). ), Pr _1-x Sr _x C
oO ₃ (0.2 _x 0.8), Nd _1-x Sr _x CoO ₃ (0.3 _x 0.7), L
a _1-x Ba _x CoO ₃ (0.1 _x 0.5), Pr _1-x Ba _x CoO ₃ (0.2 _x
0.5), one or more of which has a solid solution composition, or La _2-x Sr _x CuO ₄ (0.1 _x 0.
5), La _2-x Ba _x CuO ₄ (0.01 _x 0.5) having one or two solid solution compositions, or YBa ₂ Cu
₃ O ₇ type, BiCaSrCu ₂ O _5.5 type, having a composition of 1 × 10 ^-2 after baking.
Electrode material for electronic parts characterized by Ω · cm.