JPS594802B2 - Kouyudenritsujikisobutsu - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new high dielectric constant ceramic composition that has a high dielectric constant, particularly a significantly small temperature change rate, and a good dielectric loss tangent at high frequencies.

It is well known that porcelain containing barium titanate as a main component has been used as a porcelain dielectric material having a high dielectric constant.

These porcelains have a high dielectric constant and are often used as capacitor materials, but the higher the dielectric constant, the greater the change in dielectric constant with respect to temperature, and the dielectric constant is about 4000 (
At 20°C) or higher, the rate of change is 50% or higher (at 20°C) or higher.
(at 0°C to 85°C) and also changes greatly depending on the voltage.
It was difficult to produce a small, large-capacity capacitor of A standard x 7R). Since it is subject to large changes due to temperature and voltage or changes over time, it is necessary to allow a large margin for the initial value of the capacitance, so its high dielectric constant has not been fully utilized. 10 Also, in the case of a capacitor with a relatively small rate of temperature change (+20°C to +85°C), the dielectric constant becomes ε=1500 or more, so there are many drawbacks such as insufficient capacitance and poor high-frequency loss angle. .

As mentioned above, there are many improved materials mainly based on barium titanate, and there are still no defect-free materials for high-standard use (showing stable characteristics over a temperature range of -55°C to +125°C).

) is not suitable as a capacitor material, and recently there has been a demand for a material with a high dielectric constant and a small temperature change rate, as well as a material with a good loss angle at high frequencies. In addition, BaTi03-
Bismuth type, BaTi03-PbTi03 type BaTi0
3-PbTi03-La2o3 system, PbTiO3La2
Materials such as O3/BTi02 series are known, but these have a poor conversion rate when the dielectric constant becomes high, and furthermore, the loss angle of high frequencies is poor and the Pb component is a harmful substance in terms of pollution problems, and furthermore, PbO , Bi2O3, etc. evaporate significantly during firing, making it difficult to obtain industrially stable porcelain. 30 The present invention improves these drawbacks and provides a new high dielectric constant ceramic composition useful as a material for small-sized, large-capacity, high-standard ceramic capacitors.

That is, the porcelain composition of the present invention contains BaTi02 component powder 3592.35~
For a composition containing 99.45 mol% of Nb205, 0.45 to 5.65 mols of Cf6, and 0.10 to 2.00 mol% of Mn0, Bl2O3 is added as an additive in a weight ratio of 0.2 to 1 to the weight of the composition. This is a high dielectric constant ceramic composition characterized by containing .5 wt%. By changing the composition ratio within the above range, the dielectric constant can be adjusted to about 1500 to 3500.
It is possible to provide a ceramic capacitor that can be freely selected within the range of the above and below, and has a temperature change rate within ±15% in the temperature range of -55°C to +125°C.

Further, the capacitor material obtained within the scope of the present invention has a high dielectric constant, a small rate of change in capacitance with temperature, an extremely good high frequency loss angle (IMHZ), and a high withstand voltage. In addition, BaTlO3,N of the present invention
The reason for limiting each component of b2O5, MnO2, etc. is as follows.

That is, if the BaTiO three component powder, which is a single solid solution, exceeds 99.45 mol %, the dielectric constant will be low, the loss angle of high frequencies will be poor, and the temperature change rate will be large, which is not preferable. If it is less than 92.35 mol %, the sinterability of the ceramic body becomes unstable and the rate of temperature change becomes large, which is not preferable.

If the Nb2O5 component is 5.65 mol% or more, the dielectric constant decreases, which is not preferable. If it is less than 0.45 mol %, the high frequency loss angle will deteriorate, which is not preferable.

Furthermore, if the MnO2 component is 2.00 mol % or more, the temperature change rate will be small, but the dielectric constant will be extremely low and the loss angle will also be bad.

If it is less than 0.10 mol %, the effect of reducing the temperature change rate of dielectric constant becomes poor, which is not preferable.

When the Bi2O3 component is 1.5 wt% or more, the temperature change rate becomes small, but the high frequency loss angle becomes extremely poor. 0.2w
If it is less than t%, the effect of reducing the temperature change rate of the dielectric constant becomes poor, and the spalling resistance also deteriorates.

Note that the use of BaTiO three component powder, which has already become a single solid solution in the VC of the present invention, is a necessary condition for reducing the temperature change rate and obtaining reproducibility.
Furthermore, it is a well-known fact that in the firing of BaTiO3-based porcelain, a trace amount of MnO2 is added to prevent reducibility. That is, it was added to minimize the deterioration of the characteristic values of insulation resistance or loss angle. However, the present invention exhibits effects that are completely different from those of the conventional addition of MnO2.

That is, by simultaneously adding MnO2 and NB2O5, each cue of pallium titanate is held in the same position,
Moreover, it exhibits remarkable effects on properties such as dielectric constant temperature characteristics and dielectric loss tangent. Furthermore, if the BaTiO3 component is used as a raw material, it will easily form a solid solution with other components, and the effect of improving properties will be lost. That is, the present invention adds the Nb2O5 component-MnO2 component triangle and Bi to the BaTiO3 (single solid solution) composition within the above composition range.
By simultaneously adding the 2O3 component, it is possible to obtain extremely good characteristics such as a high dielectric constant, a small capacitance temperature change rate over a wide temperature range, a small loss angle at high frequencies, and a high withstand voltage. .

EXAMPLES The present invention will be specifically explained below with reference to Examples.

In the sample preparation process, first, equimolar BacO
3 and TiO2, respectively, and then heated to 1050℃~1
The mixture was calcined at 200° C. for 1 hour, pulverized, and then mixed in the proportions shown in the table. It was confirmed by X-rays that the BaTiO3 solid solution had become a single solid solution. 0.3wt#) of Al2 to promote the densification of mortuary porcelain.
O3 and SiO2 were added respectively. Wet mixing was performed using a urethane-lined pot mill and a urethane-lined pole to prevent contamination of impurities. After that, the moisture is evaporated, and a 15ψ x 1.2 m/m disc is press-molded at a pressure of about 750 Kf/Cd, and fired at a temperature of 1280°C to 1400°C2 in an electric furnace using an Elema heating element.
I did it by keeping time. The obtained ceramic elements were coated with silver electrode solution on both sides, baked at 750°C for 15 minutes, and their electrical properties were measured. Although BaTiO3 having an equimolar composition ratio was used in this example, good characteristics could be obtained even if the ratio was shifted by about 0.5 mol%.

Although the MnO2 component was used in this example, the same effect can be obtained with other manganese salts. In addition, trace additions of strontium, calcium, magnesium, etc.
Effective in improving characteristics. The following table is a number of examples of compositions according to the invention. The conditions for measuring heat-resistant spalling characteristics are as follows: insert the sintered element into a solder bath heated to 350°C, and then
We investigated the number of breakages when dropped onto an aluminum plate.
Here, items that break when inserted into the solder bath are also considered to be the number of breaks. In the table, 3/10 indicates that 3 out of 10 pieces were broken. Above table VC number A1-17, 30-3
6 is an example within the scope of the present invention, and the others are examples outside the scope.

All samples within the scope of the present invention can yield very fine porcelain. In addition, its electrical properties have a higher dielectric constant than conventional materials with the same temperature change rate, a good high-frequency dielectric loss tangent, and a small and stable temperature change rate over a wide temperature range. ing. Furthermore, although not shown in the examples, the breakdown voltage is also good. In addition,
In this example, materials Nos. 1 to 17 and 30 to 36 have good dielectric loss tangent, high frequency dielectric loss tangent, and temperature change rate of dielectric constant, and are optimal as capacitor materials. In particular, blacks 13 and 14 have a high dielectric constant, a small rate of change in dielectric constant with temperature, and a small dielectric loss tangent at high frequencies. Moreover, the dielectric constants from ya 18 to ya 27 are low, the rate of change of dielectric constant with temperature is poor, and the dielectric loss tangent at high frequencies is large, making them poor materials for capacitors. Moreover, although the dielectric constant and the temperature change rate of the dielectric constant were good in Nos. 28 and 29, the spalling resistance was very poor.
Also Jff). The dielectric constant is good from 37 to 40, but
The dielectric loss tangent at high frequencies, anti-spalling characteristics, and rate of change in dielectric constant with temperature were very poor. In addition, Ya 41 was a composition within the range in which the BaTiO3 component was replaced with a raw material, but good properties such as dielectric constant, temperature change rate, and dielectric loss tangent could not be obtained. Good properties can be obtained by using the BaTiO3 powder which has become a single solid solution as described above and adding subcomponents within the range.

Claims (1)

[Claims] 1 BaTiO_3, which has already become a single solid solution
Component powder 92.35-99.45% mol%, Nb_2O
_50.45-5.65 mol%, MnO_2・0.10
~2.00 mol% of the composition, Bi_2O_3 is added as an additive at a weight ratio of 0.2 to 2.00 mol% to the weight of the composition.
A high dielectric constant ceramic composition characterized by containing 1.5 wt%.