JPS6051209B2 - High dielectric constant porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high dielectric constant ceramic composition that can be used in capacitors for consumer or industrial use.

Conventional Structures and Problems There have been many known high dielectric constant ceramic compositions for ceramic capacitors that are mainly made of barium titanate (BaT100).

Barium titanate is a unique material with a ferroelectric constant of 1
It has a phase transition point (Curie point) around 20℃,
At this Curie point, the dielectric constant is 6000 to 7000.
shows an extremely high value. However, since this barium titanate alone cannot achieve a high dielectric constant at room temperature, adding additives moves the Curie point to around room temperature, allowing it to have appropriate capacitance and temperature characteristics at room temperature. Efforts are being made to put capacitors into practical use. Here, the additive used to shift the Curie point is called a shifter (BaSnOa)CaZrO. , CeO.
, Ta. 0, etc. are generally known, and high dielectric constant compositions of barium titanate using these shifters are used for capacitors. Further, in recent years, various electronics-related components have been miniaturized, and one of them is a chip-type multilayer ceramic capacitor, which is becoming a leadless chip component.

Furthermore, recently, an assembly method has been used in which such chip components are automatically attached to a printed circuit board using an automatic mounting machine, but when the chip components are crimped onto the printed circuit board by the pins of such a mounting machine, the elements of the chip components may crack. A big problem has arisen: In particular, conventional multilayer ceramic capacitors using barium titanate-based high-permittivity porcelain have low bending strength, and this problem has been a major hindrance in the development of chip components and the introduction of automatic assembly methods.
OBJECTS OF THE INVENTION The present invention aims to eliminate such conventional disadvantages and provide a barium titanate-based high dielectric constant porcelain composition that has excellent electrical properties and sufficiently high mechanical strength. purpose.

Structure of the Invention In the present invention, 1 to 10 parts by weight of CaTlO3 and Ta2O are added to parts by weight of BaTiO3lOO.
1 to 5 parts by weight of 5, 1 to 5 parts by weight of S0, SiO2
By containing 0.1 to 1.0 parts by weight of 0.1 to 1.0 parts by weight, a high dielectric constant ceramic composition was obtained which had excellent electrical properties such as voltage dependence and high frequency properties, and also had sufficiently high mechanical strength.

Moreover, using the above as a main component, Mn. ．． C
r. ．． Fe. ．． Ni. ．． A high dielectric constant ceramic composition capable of lowering the sintering temperature was obtained by containing at least one type of oxide of CO in an amount of 0.01 to 0.5% by weight based on the main component. It is known that this SiO2 is inevitably mixed in a very small amount during mixing using a normal ball mill, etc., but in the present invention, by containing an amount of SiO2 that exceeds the normal naturally mixed amount, This work succeeded in improving the mechanical strength of the porcelain composition by making it more compact.

Description of Examples Various additives are added to the BaTiO3lO volume and thoroughly mixed in a ball mill.

To a small part of this mixture SlO, 15 parts by weight of polyvinyl butyral resin as a binder, 6 parts by weight of diocphthalate as a plasticizer, and 3 parts by weight of n-butyl acetate as a solvent are added, and then wet-kneaded to form a slurry. make it into a shape. Next, this is filtered and defoamed, and then formed into a 100 μm sheet using the tractor blade method. This sheet was laminated and printed using palladium as the internal electrode material to form a multilayer structure with comb-shaped electrodes sandwiched between them.
．． 0x3.5Tn! Cut into n chips. Further, this was fired at 1250 to 1400°C for 1 to 2 hours to produce a multilayer ceramic capacitor. Tables 1 and 2 show values of bending strength and electrical characteristics of multilayer ceramic capacitors according to compositions of examples of the present invention and conventional examples.

Note that the bending strength shown here was determined by placing the sample 2 on the test holding table 1 as shown in FIG. The thickness of the sample is 0.55~0.57w! The width of n1 sample is 1.5
5±0.03 gourd, and the span of the bending strength test jig was set to 2Tfrm as shown in the figure. Also, 1. R. is DC5
Insulation resistivity measured at O■. As is clear from Tables 1 and 2, the multilayer ceramic capacitors according to the examples of the present invention have improved electrical characteristics and bending strength compared to conventional capacitors.

It should be noted that if CaTjO3 is less than 1 part by weight, the sinterability of the device will be poor and the temperature characteristics will be extremely poor, and if it is more than 1 part by weight, the dielectric constant will be low.

Also, Ta2O. If each of Sb2O3 and Sb2O3 is less than 1 part by weight, the Curie point will not fall to the room temperature range, and if it is more than 5 parts by weight, the Curie point will drop too much below the room temperature range, making it unsuitable for use in the room temperature range in either case. Furthermore, Si
If O2 is less than 0.1 part by weight, the effect of improving mechanical strength cannot be obtained, and if it is more than 1 part by weight, the dielectric constant will decrease. Also, Mn. Cr,. Fe. ．． Ni. ．． All CO oxides have a great effect of lowering the sintering temperature during element sintering, and are generally 0.01 to 0.0% of the above-mentioned main components.
The effect is recognized within the content range of 5% by weight.

Effects of the Invention As described above, according to the present invention, it is possible to obtain a high dielectric constant ceramic composition which not only has excellent electrical properties as a dielectric but also has sufficiently high mechanical strength.
In particular, it is possible to obtain an excellent composition that can realize a chip component suitable for automatic mounting as a multilayer ceramic capacitor.

[Brief explanation of the drawing]

The figure is a front view of an apparatus used for measuring the bending strength of the high dielectric constant ceramic composition of the present invention. 2... Sample.

Claims (1)

[Claims] 1 Based on 100 parts by weight of BaTiO_3, CaTiO
_3 1 to 10 parts by weight, Ta_2O_5 1 to 5 parts by weight, Sb_2O_3 1 to 5 parts by weight SiO_2 0.1 to 10 parts by weight
A high dielectric constant ceramic composition containing 1 part by weight. 2 0.01 to 0.5% by weight of at least one of oxides of Mn, Cr, Fe, Ni, and Co based on the main component
A high dielectric constant ceramic composition according to claim 1 containing: