JPH0766893B2 - Multilayer capacitor element - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer capacitor element, and more particularly to a multilayer capacitor element having a large capacity and a low electrode cost.

2. Description of the Related Art In recent years, with respect to ceramic capacitors, monolithic ceramic capacitors are rapidly becoming popular due to demands for smaller size and larger capacity of elements. Further, due to the high frequency of the circuit, it has become necessary to use a ceramic multilayer capacitor in a large capacity region of 0.1 μF or more, which has conventionally been used an aluminum electrolytic capacitor or a tantalum electrolytic capacitor.

To obtain a large-capacity ceramic multilayer capacitor while keeping the element shape small, use a dielectric with a high dielectric constant, reduce the thickness of the dielectric layer, increase the number of internal electrode layers that make up the capacitance, and It is necessary to increase the electrode area per layer.

However, when the thickness of the dielectric layer is reduced, there are problems in dielectric properties of the dielectric, and there are problems such as a decrease in withstand voltage of the device and a decrease in life characteristics. When the thickness of the dielectric layer is reduced and the number of layers of the internal electrodes is increased, the element is distorted due to the difference in shrinkage after firing between the part with internal electrodes and the part without internal electrodes, resulting in delamination and cracking. There is a problem to do. Further, the increase in the number of internal electrode layers and the electrode area per layer has a problem that the element price increases due to the internal electrode cost particularly when a precious metal electrode such as palladium is used.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a multilayer capacitor element that achieves a large capacity while maintaining a compact shape and has a low electrode cost.

Means for Solving the Problems In order to solve the above problems, the present invention provides a multilayer capacitor element in which at least two or more internal electrode layers are alternately laminated with dielectric ceramic layers interposed between the dielectric ceramic layers of Pb and Ca. Composition A containing at least Pb of Sr, Ba and Mg, Ni, Zn, C
An alloy composed of an oxide containing both of the composition B containing at least two elements of u, Ti, Zr, Nb, Ta and W, and the internal electrode layer containing palladium metal or palladium as a main component And the thickness of the dielectric ceramic layer is x μm and the thickness of the internal electrode layer is y μm, 7.0 μm ≧ x ≧ 1.0 μm 0.7 μm ≧ y ≧ 0.07 μm 100.0 ≧ x / y ≧ It was set to 10.0.

Action In the ceramic multilayer capacitor element having the above configuration,
By combining Pb-containing complex oxide-based dielectric material and palladium-based electrode material, both the dielectric layer and the electrode layer can be made much thinner than conventional ones. Poor life and structural defects are prevented, and the life is not shortened.

Examples Example-1 As the composition of the starting material for the dielectric layer, the materials represented by the following composition formulas were used.

A: Pb _1.0 (Mg _1/3 Nb _2/3 ) _0.7 Ti _1.19 (Ni _1/2 W _1/2 ) _0.11 O ₃ B: Pb _0.88 Sr _0.15 (Zn _1/3 Nb _2/3 ) _0.85 Ti _0.15 O _3.03 + MnO ₂
0.35wt% C: Pb _0.60 Ca _0.45 (Mg _1/3 Nb _2/3 ) _0.95 Zr _0.05 O _3.05 D: Pb _1.00 Ba _0.03 (Mg _1/3 Nb _2/3 ) _0.90 (Ni _1/3 Ta _2/3 ) _0.05
The (Cu _1/2 W _1/2 ) _0.05 O _3.03 dielectric powder was manufactured according to the usual shellac manufacturing method.
After calcination, the dielectric powder was wet pulverized with a zirconia boulder with a diameter of 0.6 mm using a medium stirring mill, and the average particle size was 0.14 μm.
A powder having a uniform particle size distribution was obtained. The calcined powder was slurried in a vibration mill (paint conditioner) together with 6 wt% acrylic resin, 70 wt% solvent and organic dispersant, and zirconia cobblestone with a diameter of 3 mm, and the reverse roll coater was used. The organic film used was applied to a predetermined thickness and dried.

Palladium black powder was used as the starting material for the internal electrodes, and
A three-roll mixer was used to form a slurry together with t% acrylic resin, 60 wt% solvent and organic dispersant.
This electrode paste was printed with a predetermined internal electrode pattern having a predetermined thickness on an organic film by using a gravure transfer method.

Next, the dielectric sheet formed on the organic film is pressure-bonded on a metal surface plate, and the operation of peeling off the organic film is repeated to form a predetermined internal electrode pattern on the dummy layer laminated to a predetermined thickness. The operation of pressure-bonding to the position and peeling off the organic film, pressure-bonding the dielectric sheet on it and peeling off the organic film is repeated until 51 layers of the internal electrode layers are laminated, and only the dielectric sheet is again given the predetermined thickness. A dummy layer was formed by laminating up to the thickness. The laminated body was cut at a predetermined position to obtain a laminated chip.

The laminated chip was prepared by laying coarse-grained magnesia powder in a porcelain container, heating it to 350 ° C. over 10 hours, holding it for 6 hours, and cooling it to burn out the binder. After cooling, cover the laminated chip in the container with muffle powder, which is a mixture of dielectric calcined powder and coarse-grained magnesia in a weight ratio of 1: 3, until the laminated body is covered, cover the magnesia container, and re-tube. Inserted in the furnace core tube, 8ppm oxygen-containing nitrogen gas at 300c / min
While flowing c, the dielectric material A was heated to 1000 ° C., and B, C, and D were heated to 850 ° C. at 300 ° C./hour, held for 45 minutes, and then cooled to room temperature.

After firing, the laminated chip was coated with a baking silver paste on the cross-section where the internal electrodes were exposed and baked in air at 700 ° C. for 10 minutes to form external electrodes.

The prepared multilayer capacitor element has an outer shape of 3.2x1.6x1.25mm and the effective area per one electrode layer is 2.97mm ² .

The created multilayer capacitor element is 20 ℃, 1kHz, signal voltage
Measure the capacity and tan δ with 1V AC and apply 5V DC voltage. 1
The resistance value of the minute value was measured. Furthermore, a DC voltage of 50 V was applied to each of the 10 samples, and the presence or absence of dielectric breakdown was examined.
For each of the other 10 samples, the humidity is 85%
After applying a DC voltage of 5 V and leaving it for 200 hours, the insulation resistance of the device was measured and the resistance was 1 × 10 ⁷ or less. For each of 10 other samples, the internal electrode layers were polished and exposed perpendicularly to the electrode surface, and the presence or absence of delamination and cracks in the samples were confirmed.

Table 1 shows each sample number, its dielectric composition, dielectric layer thickness,
Show the electrode film thickness. The electrode layer thickness was calculated from the amount of solid content applied during printing. Table 2 shows the above measurement results of each sample.

As is clear from Tables 1 and 2, the multilayer capacitor element of the present invention can be made much thinner than the conventional one, the capacitance can be obtained almost according to the calculated value, and the structural defects are almost eliminated. Good characteristics are obtained. If the dielectric thickness is less than 1.0 μm, it is considered that the dielectric layer lacks the denseness and there is a through hole between the electrodes, so that a dielectric breakdown life failure occurs. If the thickness of the electrode layer is 1.0 μm or more or the ratio to the thickness of the dielectric layer is 10 or less, defects occur between the dielectric layer and the electrode layer, resulting in dielectric breakdown and poor life. Electrode layer thickness is 0.07μ
If m or less, the continuity of the electrode is lost and the capacity is reduced.

Example-2 A and D of Example-1 were used as the dielectric raw material, the electrode raw material was the same as in Example-1, and sample Nos. 7 and 22 in Table 1 and Table 2 were laminated in the same manner. , Burned out the binder. After cooling, cover the laminated chips in the container with muffle powder, which is a mixture of the calcined dielectric powder and the coarse-grained magnesia in a weight ratio of 1: 3, until the laminated body is covered, cover the magnesia container, and air this time. Among them, 1000 ° C for dielectric material A and 8 for B, C, D
The temperature was raised to 50 ° C at 300 ° C / hour, held for 45 minutes, and then lowered to room temperature.

The laminated chip after firing was applied with a baking silver paste on the cross section in which the internal electrodes were exposed in the same manner as in Example-1, and 700
It was baked at 10 ° C. for 10 minutes and used as an external electrode. The produced element has an outer shape of 3.2 × 1.6 × 1.25 mm and an effective area of 2.97 mm ² per electrode layer as in Example 1.

The created multilayer capacitor element is 20 ℃, 1kHz, signal voltage
Measure the capacity and tan δ with 1V AC and apply 5V DC voltage. 1
The resistance value of the minute value was measured. Further, a DC voltage of 250 V was applied to each of the 10 samples, and the presence or absence of dielectric breakdown was examined.
For each of the other 10 samples, the humidity is 85%
After applying a DC voltage of 12.5 V and leaving it for 200 hours, the insulation resistance value of the device was measured and the device having a resistance value of 1 × 10 ⁷ or less was determined to be defective. For each of 10 other samples, the electrode layer was polished and exposed on a surface perpendicular to the electrode surface, and the presence or absence of delamination and cracks in the sample was confirmed.

Table 3 shows the above measurement results of each sample.

As is clear from Table 3, the element which is obtained by firing the element in air and containing Pb in the electrode and containing Pd ₃ Pb as a crystal phase is
Dielectric breakdown does not occur up to high voltage and life characteristics are improved.

EFFECTS OF THE INVENTION According to the present invention, it is possible to reduce internal defects caused by the difference in firing shrinkage and thermal expansion between the electrode part and the dielectric part,
Not only the reliability of the multilayer capacitor element using a thin dielectric layer is improved, but also the electrode cost is reduced by making the electrode layer thinner.

Front page continuation (72) Inventor Koichi Kugimiya 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP 62-86814 (JP, A)

Claims (2)

[Claims] 1. A multilayer capacitor element in which at least two or more internal electrode layers are alternately laminated with a dielectric ceramic layer interposed therebetween, wherein the dielectric ceramic layer is at least Pb among Pb, Ca, Sr and Ba.
Composition A containing Mg, Ni, Zn, Cu, Ti, Zr, Nb, Ta and W
Of the composition B containing at least two elements, and the internal electrode layer is formed of palladium metal or an alloy containing palladium as a main component, and the thickness of the dielectric porcelain layer is The thickness is x μm, and the thickness of the internal electrode layers is y μm, 7.0 μm ≧ x ≧ 1.0 μm 0.7 μm ≧ y ≧ 0.07 μm 100.0 ≧ x / y ≧ 10.0. 2. The internal electrode layer is mainly composed of Pd including Pb,
The multilayer capacitor element according to claim 1, which contains Pd ₃ Pb.