JPS6056307A - Ferrodielectric porcelain composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a high dielectric constant ceramic composition that can be used in ceramic capacitors, particularly multilayer ceramic capacitors.

Structure of conventional example and its problems Conventionally, barium titanate B was used as a high dielectric constant porcelain composition.
A material whose main component is a T 10 a and whose properties are improved by adding appropriate amounts of calcium zirconate Ca Z r Os , calcium titanate CaTi0 , calcium stannate CaSnO3, strontium titanate 5rTi03, etc., has been widely put into practical use. There is.

However, the firing temperature of these high permittivity ceramic compositions is high, approximately 1300'C to 1400°C, and when making a multilayer ceramic capacitor using these ceramic dielectric materials, the internal electrodes of the multilayer ceramic capacitor are made of a dielectric material. Since it is necessary to sinter the internal electrode while it is embedded in the porcelain material, it is necessary to use platinum or palladium, which is stable even at the above-mentioned high temperature of 1300 DEG C. to 1400 DEG C., as the material for the internal electrode. However, precious metals such as platinum or palladium are very expensive.

As the applications of multilayer ceramic capacitors have expanded in recent years, inexpensive silver or silver thread alloys can be used as internal electrodes. That is, the development of porcelain dielectric materials that can be sintered at temperatures of 1000° C. or lower is being actively conducted, and most of these materials are mainly composed of composite perovskite compounds containing lead. Among the high dielectric constant ceramic compositions containing these composite perovskite type compounds as main components, the above-mentioned conventional barium titanate B a -T
Many materials with a higher dielectric constant than high dielectric constant ceramic compositions whose main component is 10s have been found, and those whose main component is magnesium lead niobate pb (Mg%Nb%) O3 have a dielectric constant. However, there are some cases where the amount is about 0.
In materials with such a high dielectric constant.

This is an important problem when producing multilayer ceramic capacitors using these materials, as the dielectric constant varies widely from lot to lot, and it is difficult to modify the capacitance after sintering in multilayer ceramic capacitors. was.

Object of the invention The present invention provides magnesium lead niobate P b (Mq3AN
The purpose is to suppress variations in the dielectric constant of the composition containing b%)03 as a main component and to improve the yield in manufacturing multilayer ceramic capacitors.

Structure of the Invention In order to achieve the above object, the present invention takes into consideration the above drawbacks and provides a method for adjusting the dielectric constant and the amount of silicon dioxide Si02 contained in the composition as a magnesium lead niobate Pb (MghNb, A)03 product component. The present invention relates to a high dielectric constant ceramic composition in which variations in dielectric constant are suppressed by controlling the amount of silicon dioxide 5lo2 to 0.07 weight nanometers or less.

Description of Examples The composition after sintering is [P b (F eX town) olo (Mq
hNbx)o,asTion5os+5.0wt%Pb
The medium in the ball mill was agate. be. A multilayer ceramic capacitor was created using this composition, and its dielectric constant was calculated. In addition, the amount of silicon dioxide S in the above composition was changed to
It was analyzed using a line instrument. The results are shown in the drawing.

As shown in the drawing, in a porcelain composition whose main component is magnesium lead niobate, the amount of silicon dioxide in the composition is o, 0.
If it exceeds 7% by weight, the dielectric constant decreases significantly to approximately 130% by weight.

Therefore, we use raw materials containing less silicon dioxide, such as lead oxide, magnesium oxide, and niobium oxide, and at the same time, we use silicon dioxide S102 produced by abrasion of agate boulders.
In order to suppress the contamination of silicon dioxide S102, the amount of silicon dioxide S102 was determined by considering the amount of agate cobblestone, raw materials, water, etc. input to the ball mill. , 07% by weight or less. As a result, when 20 samples of the above composition were prepared, the dielectric constant varied by up to 21,000. It is now possible to suppress the number to a minimum of 18,500.

Note that the capacitance for calculating the dielectric constant was measured at 25° C. and a frequency of 1 kllz.

It is also possible to use alumina balls or zirconia balls instead of agate stones as the medium in the ball mill, but when alumina balls are used, the dielectric constant decreases due to the alumina mixed in, and the dielectric loss angle δ increases. It gets bigger and I don't like it. Furthermore, when zirconia balls are used, the sintering temperature increases to 1050° C. or higher due to the inclusion of zirconia, which is not preferable.

Effects of the Invention As detailed above, the present invention suppresses variations in dielectric constant by controlling the amount of silicon dioxide in a composition containing lead magnesium niobate P b (M q3AN b%) o3 as a main component. This is called the rjj function, and is of great value in the production of ceramic capacitors.

[Brief explanation of drawings]

The drawing shows the relationship between the amount of silicon dioxide Sio2 in the porcelain composition and the dielectric constant, and the horizontal axis represents the amount of silicon dioxide Sio2
The content of 2, the vertical axis shows the dielectric constant.

Claims (1)

[Claims] When the amount of silicon oxide S i02 in the composition mainly composed of magnesium lead niobate Pb (Mq3ANb%) o3 is 0
．． 07fl! % or less.