Compositions: ceramic – Ceramic compositions – Titanate – zirconate – stannate – niobate – or tantalate or...
Patent
1983-03-07
1985-12-10
McCarthy, Helen M.
Compositions: ceramic
Ceramic compositions
Titanate, zirconate, stannate, niobate, or tantalate or...
361322, C04B 3546
Patent
active
045580200
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to ceramic high dielectric composition to be used mainly as capacitor.
BACKGROUND ART
Hitherto many proposals have been made on ceramic high dielectric compositions with barium titanate as host material, and they have been used specially for disc type ceramic capacitors.
The barium titanate is a material having ferrodielectric characteristic, and its Curie point lies around 120.degree. C. Demarcated by this 120.degree. C., in the lower temperature side thereof it becomes tetragonal, and in the upper temperature side thereof it becomes cubic. And it is well known that in the tetragonal region it shows ferrodielectric characteristic and in the cubic region it shows paraelectric characteristic.
Since, ceramic of such sole barium titanate has a very large change of dielectric constant dependent on temperature and also has a large dielectric dissipation in a temperature range of about normal temperature, it is hardly used as capacitor independently; and hitherto devices are made to shift the Curie point to around the normal temperature, and to decrease the temperature dependency by adding various additives. CaTiO.sub.3, BaZrO.sub.3, SrTiO.sub.3, BaSnO.sub.3 or the like are known as representative of the additives. By adding these appropriately and by adjusting with a small amount constituent, material having characteristics of X7R, Y5T, Y5V, Z4V or the like of EIA standard are provided.
The fact is that these materials are hitherto utilized generally as ceramic capacitors of thick disc type, for instance having 0.5-1 mm thickness of element.
In these years, miniaturization of capacitors is progressing corresponding to miniaturization of various electronics-related components, and the most in multiple layer ceramic capacitors. The multiple layer ceramic capacitor is that in which ceramic dielectric body is made into thin film of around 25-100 .mu.m and sandwiched with comb type electrodes to form a multiple layer construction; and since a ratio of electrodes area to electrode gap can be made very large, its capacitance per volume can be made as large as 100 times or larger in comparison with the ceramic disc type capacitor, and the same capacitance can be assured with as small volume as 1/10 or less, and therefore miniaturization is very easy.
When such ceramic dielectric thin film is used, however, it is the fact that conventional disc type ceramic composition can not be used as it is. That is, since a voltage per unit length is loaded 10 times or more than the conventional case, a material having small voltage-dependencies of ceramic dielectric constant and small dissipation factor become to be needed. Besides, due to recent direct bonding system onto printed circuit board, a strong material which is not destroyed by bending of the print circuit board is needed. Further, since the frequencies are shifted to higher band of high sensitivities, those which have good high frequency characteristics become necessary. Especially, those having characteristic of YD in JIS (Japanese Industrial) standard or characteristic of Y5T in EIA (Electronic Industries Association) standard are requested by a large number in relation to electronic tuner, those which have dielectric constant of 3000 or above and tan .delta. of 2.0% or lower and low equivalent series resistance at frequency band of 1-100 MHz are requested.
DISCLOSURE OF THE INVENTION
Accordingly, the present invention is to provide ceramic high dielectric composition having dielectric constant as high as 3000 or above, small voltage dependency, large bending strength and good high frequency characteristics, by containing as additive 1-5 weight parts of CaTiO.sub.3 and 2-3 weight parts of Nb.sub.2 O.sub.5 to 100 weight parts of BaTiO.sub.3.
BRIEF EXPLANATION OF THE DRAWING
FIG. 1 is a partially sectional front view of a multiple layer ceramic capacitor trially made by using the composition of the present invention,
FIG. 2 is a graph showing frequency characteristics of equivalent series resistance of the same cer
REFERENCES:
patent: 4014707 (1977-03-01), Tanaka et al.
patent: 4073989 (1978-02-01), Wainer
patent: 4096098 (1978-06-01), Umeya et al.
patent: 4222783 (1980-09-01), Atsumi et al.
Ceramic Industry, Jan. 1967, p. 44, "Calcium Titanate".
Dictionary of Mining, Mineral and Related Terms-pub. by Dept. of Interior (1968) p. 809, "Perovslsite".
Graf, R. G., "Effect of Impurities Upon the Dielectric Properties of Barium Titanate", Ceramic Age (Dec. 1951) pp. 16 and 18-19.
Iguchi Takashi
Itakura Gen
Kuramitsu Hideki
Kuroda Takayuki
Nagase Kaneomi
Matsushita Electric - Industrial Co., Ltd.
McCarthy Helen M.
LandOfFree
Ceramic high dielectric composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ceramic high dielectric composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ceramic high dielectric composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-58861