JPS6050004B2 - High dielectric constant porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high dielectric constant ceramic composition that can be sintered at an extremely low temperature of 100°C or less.

The conventional high dielectric constant dielectric is barium titanate (BaT1O
3) Those containing strontium titanate (SrTiO3) as a main component are widely put into practical use.

However, these BaTiO3, SrTiO. The firing temperature for those whose main component is usually 1300 to 1400℃
It will not sinter unless it is at a high temperature. Therefore, in order to manufacture high-quality multilayer ceramic capacitors and thick film capacitors, the internal electrodes used in these capacitors must be made of expensive materials such as platinum, platinum-palladium alloys, and palladium that can withstand the temperatures at which the dielectric material sinters. The disadvantage is that precious metals must be used, and the material cost for the internal electrodes accounts for 70% of the cost, which is an obstacle to reducing the cost of multilayer ceramic capacitors and thick film capacitors. In order to reduce costs, there is a need for a low-temperature sintered material that allows the use of inexpensive electrodes containing silver as the main component for internal electrodes. It is a porcelain that can be bonded and has a high dielectric constant.
The object of the present invention is to provide a high permittivity ceramic composition that has excellent dielectric properties such as low dielectric loss and high specific resistance.

The present invention is Pb(Mgl/3Nb2/3)O.

-CdTi0a-JPb(Fe2/3W1/3)00
By adding excessive amounts of PbO and MgO to the ternary composition, the sintering temperature can be lowered and sintering can be performed at 1000°C or lower, and the dielectric constant becomes significantly large at temperatures around room temperature, resulting in small dielectric loss. We invented a high-permittivity ceramic composition with high specific resistance and high performance. That is, the ceramic composition of the present invention has Pb(Mgl/3Nb2/3)03
A ternary composition consisting of [Pb(Mgl/3Nb2/3)
03]XCCdTiO3]y[Pb(Fe2/3W1/
3) When expressed as 03]z, X, y, z are x=30~
98n101%, y=1~35n101%, z=1~3
PbO2 to 20 Wt%, MgOO. l~
This composition is characterized in that an excess of 5 wt% is added, and at least one of Mn, CO, Ce, Cr oxides and viscosity substances is added to this composition in an amount of 0.01 to 0.01%.
This is a composition containing 0.5 wt%.

The ceramic composition of the present invention can be sintered at temperatures near the melting points of silver and silver-noble metal alloys (below 1000°C), and can be used as a dielectric material for multilayer ceramic capacitors and thick film capacitors using the composition for internal electrodes. The manufacturing cost of these capacitors can be significantly reduced due to the inexpensive internal electrodes.

Hereinafter, the present invention will be explained in detail together with examples.

Each raw material of lead oxide (PbO), magnesium oxide (MgO), niobium oxide (Nb, O5), titanium oxide (TiO2), cadmium oxide (CdO), iron oxide (Fe2O3), and tungsten oxide (WO3) is The composition shown in Table 1 was weighed so that the total weight was 100f.

Along with these raw materials, we also use 150f1 pure agate stone.
After mixing 120y of water in a ball mill to make a slurry,
Let solidify and dry. Next, the dried material is placed in an alumina crucible and calcined at 700 to 850°C. 5 to 30V of this calcined powder
After adding 1.8g of %PVA solution and mixing uniformly, about 70% PVA solution was added and mixed uniformly.
At a pressure of 0 kg/Clt, the diameter is 15 mm and the thickness is about 0.4? It was molded into. This molded body was fired at 900 to 1000°C for 1 hour to obtain a sintered body. A conductive silver paste was applied to this sintered body to form electrodes, and the electrical properties were measured. The measurement results are also shown in Table 1. As is clear from Table 1, the ceramic composition within the scope of the present invention has a large dielectric constant (ε
= 1000 to 20000), and the dielectric loss is extremely small (
Tan δ = 0.3 to 3.5%), and the specific resistance is 1011
Sintering is possible at a temperature of Ω·α or more and at a low temperature of 1000°C or less. In addition, as shown in Table 1, those outside the composition range (1) are not sintered.

(2) Low dielectric constant even after sintering.

(3) Dielectric loss is large even after sintering.

The result is a composition with materials and material properties such as , which cannot be used as a dielectric material.

Therefore, [Pb(Mgl/3Nb2/3)03]X
[CdTlO3]YCPb(Fe2/3W1/3)03
]03+Awt%PbO+Bwt%MgO, the range of X, y, z is 30<x<98,1×y<35
, 1〈z〈35.

If it is outside this range, Tc (K** Ury point) will deviate greatly from room temperature and ε will become 1000 or less. In addition, the excessive addition of PbO, MgO (7) A, B was limited because
100 for 渥% yen O>A and 0.1Wt%MgO>B
It does not sinter at low temperatures below 0°C.

Note that when 20Wt%PbO<Al5Wt%MgO<B, there is a large deviation from the stoichiometry, so the ceramic becomes porous and the dielectric loss increases. The figure shows a composition diagram of the ternary component system according to the present invention, and the numbers in the figure are NO. It corresponds to Table 2 below shows the measurement results when a mineralizing agent was added.

At least one of Mn, Ce, Cr, and CO oxides and viscosity substances are used as a mineralizer, and 0.01
By adding and containing ~0.5 Wt%, the sinterability of the porcelain is good, and it is effective in improving the dielectric loss and temperature characteristics. As described above, the porcelain composition of the present invention has 1
It is sintered at a low temperature of 0.0000 or below, and is suitable as a material not only for ordinary disk capacitors, but also for multilayer ceramic capacitors and thick film capacitors that require miniaturization and large capacity. It becomes possible to use silver-based electrodes, and product costs can be reduced.

On the other hand, since it is fired at a temperature of 1000° C. or lower, it is an excellent composition that allows the use of an inexpensive firing furnace and saves thermal energy.

[Brief explanation of the drawing]

The figure is a ternary composition diagram of the porcelain composition according to the present invention.

Claims (1)

[Claims] 1 Magnesium lead niobate {Pb (Mg1/3Nb
2/3) O_3} and cadmium titanate {CdTiO_
3} and iron/lead tungstate {Pb(Fe2/3W1
/3) A ternary composition consisting of O_3 [Pb(Mg1
/3Nb2/3)O_3]x[CdTiO_3]y[P
When expressed as b(Fe2/3W1/3)O_3]z,
The range of x, y, and z is x = 30 to 98 mol%, y = 1 to 35 mol%, z = 1 to 35 mol% (however, x + y + z = 100), and lead oxide is added as an additive to 100 of these compositions. (PbO) from 2 to 20 wt%, magnesium oxide (
A high dielectric constant ceramic composition characterized in that 0.1 to 5 wt% of MgO) is added. 2 At least one of Mn, Co, Ce, and Cr oxides and viscosity substances are added in an amount of 0.01 to 0.0% relative to the main component.
The high dielectric constant ceramic composition according to claim 1, containing 5 wt%.