JPH013046A - Dielectric ceramic composition with high dielectric constant - 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 [Summary of the Invention] A ceramic dielectric composition or a dielectric composition having a dielectric constant of 100 or more, a dielectric loss tangent of 0.1% or less, and a temperature coefficient characteristic of less than 150 ppm/°C. Sintering is possible at temperatures below 1140°C.

[Industrial application field]

The present invention has a dielectric constant (K) of 100 or more and a dielectric loss tangent (DF).
is 0.1% or less, and the temperature coefficient characteristic (TCC) is 150p.
pm/''C or less. This dielectric composition can be sintered at a temperature of 1140° C. or less.

[Conventional technology]

Multilayer ceramic capacitors are generally made by using an insulating layer of dielectric ceramic powder by casting or other methods.
On top of this, a conductive metal electrode layer made of a palladium/silver alloy is usually placed in the form of a metal paste, and after stacking a large number of layers alternately and integrating them, they are sintered to increase the density and form a multilayer capacitor. . Since a multilayer ceramic capacitor has very stable temperature coefficient characteristics, the dielectric constant of its dielectric ceramic composition does not exceed about 80.

However, this dielectric ceramic composition is not sufficient for use in electrical circuits that require capacitors with both a low dissipation factor and very stable temperature coefficient characteristics. The material has a dielectric constant whose temperature change (TCC) does not exceed +/- about 150 ppm/''C per 1°C from the reference value at 25°C (room temperature).The insulation resistance time capacity of this composition Insulati
on Re5istance Time Capacit
ance product) is greater than about 100 ohm farads at 25°C, and the high operating temperature (usually 12
5° C.) is required to be greater than about 100 ohm farad. It is also necessary that the dielectric constant (K) be as high as possible and the dielectric loss tangent (DF) as low as possible.

[Problem to be solved by the invention]

The purpose of the present invention is to have a dielectric constant of about 100 or more and a dielectric loss tangent of about 0.
．． A ceramic dielectric composition suitable for manufacturing a multilayer ceramic capacitor with an insulation resistance (R) time capacitance (C) product (RC) of 1% or less and about 1000 ohm Farad or more at 25°C and about 100 ohm Farad or more at 125°C. It's about providing things.

Furthermore, it is an object of the present invention to provide a ceramic dielectric composition with stable TCC characteristics. Its characteristics are 25℃
+/-150p per 1°C of temperature relative to the reference value at
It has a dielectric constant or capacitance change not exceeding pm/'C.

The present invention further provides a ceramic dielectric composition having the following properties. In other words, it is an electrode material consisting of 70% W and 30% palladium, can be sintered at temperatures below 1140°C, can be used for manufacturing multilayer capacitors, and has the above characteristics. It is.

Other objects of the invention are partly self-evident and partly hereinafter described.

The above objectives indicate that the dielectric composition of the present invention consists of the following:

That is, about 0 to 0.68% by weight of strontium oxide, about 6.61 to 8.69% by weight of barium oxide, about 8632 to 1.15% by weight of lead oxide, about 52.08 to 55.03% by weight of neodymium oxide, Titanium oxide approx. 28.7
6 to 29.88% by weight, about 84.7 to 86% by weight of the precursor material having a major constituent of about 0 to 0.06% by weight of manganese oxide.
．． 4% by weight and about 13.61-15.3% by weight of the molten composition with the following being the major constituents: In addition, the melt composition contains about 10.00 to 10 bismuth titanate.
．． 20% by weight, about 0.10% by weight of manganese carbonate, about 0.25-0.26% by weight of niobium pentoxide, 2.35% by weight of lead oxide
4.35% by weight, about 0.09-0.50% boron oxide and about 0.28-0.70% silicon oxide.

The present invention has a dielectric constant of about 100 or more and a temperature coefficient characteristic (TC
The present invention provides a dielectric ceramic composition having C) of +/-150 p pm/'C or less and a dielectric loss tangent of 0.1% or less.

Such ceramic compositions are made by firing the constituent oxides or precursor materials at temperatures below 1140°C.

The multilayer capacitor according to the present invention has characteristics such as high dielectric constant, low dielectric loss tangent, and stable temperature coefficient characteristics, so that it has stable temperature coefficient characteristics and low loss characteristics. Can be used in electronic devices that require Specific examples of this include TV tuners and resonant circuits.

Means for Solving Problem C] In embodying the invention, a ceramic dielectric composition is made from the following main constituent mixture.

That is, about to, oo weight percent bismuth titanate, about 0
．． 1% by weight manganese carbonate, about 0.25% by weight niobium oxide, about 4.23% by weight lead oxide, about 0.21% by weight boron oxide, about 0.51% by weight silicon oxide and about 84% by weight.
702i is a precursor material consisting of the following main constituents: Note that the precursor material is comprised of about 8.47% by weight barium oxide, about 10.38% by weight lead oxide, about 52.05% by weight neodymium oxide, and about 29.13% by weight titanium oxide. . Fired ceramic bodies according to the invention are made by simultaneously reacting and firing the constituent dielectric oxides in ceramic manufacturing. This dielectric oxide consists of acids (hybarium, strontium oxide, neodymium oxide, lead oxide, titanium oxide and manganese oxide as the main constituents and ceramic precursor materials and bismuth titanate, manganese carbonate, niobium pentoxide, lead oxide, It consists of a molten composition whose main constituents are boron and silicon oxide.

In preparing the ceramic composition, strontium oxide, barium oxide, neodymium oxide, lead oxide, titanium oxide, and magnesium oxide are slurried in water or physically blended and fired. The calcined product is ground to fine particle size to form the precursor composition. The precursor composition is slurried in water or physically blended with bismuth titanate, manganese carbonate, niobium pentoxide, lead oxide, boron oxide, and silicon oxide.

The mixture for ceramic preparation is shaped into sheets using standard methods. After that, 70% silver and 30% palladium
The multilayer capacitor is molded into a multilayer capacitor along with internal electrodes made of the alloy, and fired at a temperature of 1140° C. or less for 1 to 4 hours.

The fired dielectric composition according to the present invention has a dielectric constant (K) of 100 or more, a dielectric loss tangent (DF) of 0.11% or less, and a temperature coefficient characteristic (TCC) of +/-150p pm/''C or less. .

The present invention will be specifically illustrated by the following examples.

〔Example〕

50 g of each of the K-koji % I 1 ceramic precursor compositions in the weight percentages shown in Table 1 were weighed out and placed in deionized water using a high speed spec model 800-2 manufactured by Spec Industries Inc. (Speck Industries, Inc.). Mix it evenly with a paint mixer. This precursor composition consists of strontium oxide (
SrO), barium oxide (Bad), lead oxide (PbO), neodymium oxide (Nb
20s), titanium oxide (TiO2) and manganese oxide (MnO□).

The neodymium oxide used in the present invention has recently been found to be 99.5% by weight.
The main impurity is lanthanum oxide (L
azOi). All other materials used in this invention have a purity of 99.9% by weight or higher.

In practice, other forms such as carbonates, nitrates and hydroxides can also be used provided that: That is, the final composition after the individual oxides are decomposed is the first
After uniformly mixing the above materials, which may be equivalent to those listed in the table, the slurry is dried and then
Bake at 1150°C for 1 to 4 hours. The baked product is ground in a mortar and sifted through a 325 mesh sieve.

About 65.6% by weight of bismuth titanate (Bi, Ti207), about 6% by weight of niobium pentoxide (Nb20s), about 24.4% by weight of lead oxide (PbO), boric acid (H, BO,) About 3.2% by weight of boron oxide (82ON), silicon oxide (S
About 4.5% by weight of i 02 ) and about 0.6% by weight of manganese oxide (MnO□) are added to the main constituent and molten composition and mixed into the precursor composition. The weight ratio of melt composition to precursor composition is about 0.18. Place this ceramic powder in a mortar and add approximately 26% water by weight and propylene glycol.
About 2.4 to 4.00 ml of binder solution containing about 26% by weight and about 48% by weight of corn syrup is added, mixed, and then granulated through a 40 mesh nylon screen.

The final kneaded material is formed into a disk with a diameter of approximately 27 cm and a thickness of approximately 0.1 to 0.15 cm, and this is placed in a stainless steel die at a rate of approximately 38,000 per square inch.
Press with 0 bond pressure. The disk is placed on a fixed silconia setter and fired at about 1100-1140°C for about 1-4 hours. After cooling, apply a silver electrode to the disk and sinter the electrode at about 845°.
Bake at C. Model ES1211 shows the temperature change in capacitance with respect to capacitance at 25”C (TC) of the fired product.
Measure with a 0A capacitance bridge. Measurement conditions are approximately 20°
0 intervals over a temperature range of about -55°C to about +125°C with an IKHz measurement frequency.

The dielectric constant of each sample (K) is calculated using the following formula (capacitance formula).

K= (5,66,C3T)/(D,D)...(1) However, K=dielectric constant of sample T=thickness of 1 inch disk D=diameter of 1 inch disk C=electrostatic of disk Capacity (picofarad) The temperature coefficient characteristic (TCC) of each sample is calculated by the following formula:
Calculated from the slope of the curve.

TCC= (C(CT C25) / C25) /
(T-25))XIO'...(2) However, TCC indicates the temperature coefficient in ppm/'C,
CT is the capacitance of the sample at temperature T, and C2
5 indicates the capacitance of the sample relative to the reference value of 25°C. T indicates the temperature at which CT was measured.

As summarized in Table 2, the dielectric properties of the disk sample with composition 15 in Table 2 indicate the following: That is, the dielectric constant of the ceramic composition according to the present invention is about 100.
Above, the dielectric loss tangent is 0.06% or less, and the TCC
The value is 150 ppm/°C or less.

When the BaO concentration in the precursor composition is about 1.0% by weight or more, as in composition 10 of Table 1, or when the Sr concentration in the precursor composition is about 2.0% by weight, as in composition 11. In these cases, it becomes difficult to sinter the ceramic. When the pbo concentration in the precursor composition is about 1462% by weight or more, such as compositions 12.13 and 14.15, the TCC value is on the low temperature side (about -5
5 to +25°C).
ct > or both sides thereof are greater than about 150 ppm/'C.

One burner [approximately 280 kg of ceramic precursor composition contains approximately 8.47% by weight of barium oxide (Bad), approximately 10.38% by weight of lead oxide (PbO), neodymium pentoxide (Nd20i) (
') about 52.02% by weight and about 29.1% of titanium oxide
It is made by uniformly mixing 3% by weight. The slurry is then dried and fired at about 1100-1150'C for about 4 hours.

The calcined product is then jet milled to a particle size of approximately 5 microns or less.

Approximately 50 g of this pulverized material is further mixed with a molten composition consisting of the following materials at the weight percentages and mixing ratios shown in Table 3. This melt composition contains bismuth titanate (Bi2Ti207), manganese carbonate (MnCo3
), niobium pentoxide (Nb20s >, lead oxide (PbO
), boron oxide (B203), boron pentoxide (B2
o, ) and silicon oxide.

Sintered ceramic discs are made in the same manner as described in Example 1. The dielectric properties of these disk samples are summarized in Table 4. This example further illustrates the following. That is, the ceramic composition according to the present invention has a dielectric constant of about 10 with a dielectric loss tangent of about 0.08% or less.
0 or more, and the TCC value is about 60 ppm/''C or less.

The slurry of ceramic composition and binder is approximately 16
After being mixed for an hour, it is filtered through a 44 micron screen. This slurry has a viscosity of approximately 1500-3000 centipoise. Afterwards, the slurry is degassed using the conventional method (
The tape is formed into a 5 ml thick tape using standard techniques).

The resulting tape is laminated with internal electrodes consisting of approximately 70% palladium and 30% silver and formed into a multilayer capacitor using conventional industrial techniques. The shaped capacitor is placed on a fixed silconia setter, preheated at 260°C for about 48 hours, and then sintered at about 1080-1140°C for about 1-4 hours. Sintered capacitors have 10 to 25 dielectric layers, with dielectric thicknesses ranging from about 0.85 to 10 mm.

DuPont Silver Paint No. 4822 terminal electrodes are a mixture of silver and glass melt in a binder and are used on opposite ends of a laminated capacitor to bond alternating laminated electrodes, then tunneled. 8 in the furnace
Melt at 15°C.

Capacitance (C), dielectric dissipation factor (DF), product (RC) of insulation resistance (R) and capacitance (C) at 25°C and 125°C of the obtained multilayer capacitor, and at 25°C The change in capacitance at a temperature of 1°C (TCC) for the capacitance of "General Radio 1683 Automatic RLC Bridge Radio Meter IM 6 Megohm Meter" and "Electro Scientific Industries 2111OA Capacitance Bridge"
and measured using a computer-controlled microprocessor.

Capacitance and dielectric loss tangent were measured at both IKHz and I MHz measurement frequencies.

The insulation resistance was measured by the amount of DC voltage used, and the RC product was calculated. Also measure the DC dielectric strength.

Next, calculate the dielectric constant of each sample (K) using the following formula (basic capacitance formula).

K=(((,T)/8.854 XIO-th L, W, N)...(3) However, K=
Dielectric constant of sample T = Thickness of each type of electric layer C = Measured capacitance value (Farad) L = Length of fired electrode (am) W = Width of fired electrode (cm) N = = Characteristic Number of dielectric layers (10) As shown in Table 6, the dielectric properties of the multilayer ceramic capacitors having compositions 32-34 in Table 5 express the following facts. That is, the ceramic composition of the present invention has a dielectric constant of 100 or more, a dielectric loss tangent of 0.05% or less at IKHz, a TCC value of 60 ppm/°C or less, and a dielectric loss tangent of 0.1 at IMHz.
5%, therefore, the present invention is suitable for electronic applications requiring capacitors with very stable temperature characteristics.

The numbers shown in this example are intended to account for variations from coefficients known in the art. For example, the dielectric constant for composition 34 in Table 5 can be significantly increased by grinding and kneading the ceramic composition to uniformly disperse the particles, or by forming the starting material into highly lia, 4III particles.

In practice, in the manufacturing process of ceramic capacitors,
Work will be carried out for this purpose. However, Table 5 Composition 3
This method has not been used sufficiently in the preparation of 4.
Changes in firing conditions, sample thickness, and errors in preparation and measurement can cause differences in characteristic values even for the same composition. In this way, due to slight differences in manufacturing technology, particle size, properties, etc. of ceramic compositions, even if the
Even for ceramic compositions made with the proportions shown in Table 34, the properties vary from the values shown. In other words, the dielectric constant changes up to 10, and the dielectric loss tangent is ±
It varies up to 0.02%. Furthermore, the capacitance at 25°C changes by ±10 ppm/'C per 1°C.

The invention is not limited to the description set forth herein, which is to be understood as being intended only as a description of the best mode of carrying out the invention. It extends to all modifications included within the scope.

Patent applicant Tam Ceramics

Claims (1)

[Scope of Claims] (1) Mainly about 0 to 0.68% by weight of strontium oxide, about 6.61 to 8.69% by weight of barium oxide, about 8.32 to 11.15% by weight of lead oxide, and about about neodymium oxide. 52.08-55.03% by weight, approximately 28.7% titanium oxide
6-29.88% by weight, about 0-0.0 magnesium oxide
about 84.7-86.4% by weight of a precursor material consisting primarily of about 6% by weight of bismuth titanate, about 10.00-10.20% by weight of bismuth titanate, about 0.1% by weight of manganese carbonate, about 0.1% by weight of niobium pentoxide. 25-0.26% by weight, approximately 2.3% lead oxide
5-4.35% by weight, approximately 0.09-0.50 boron oxide
% and 13.61 to 15.3% by weight of a molten composition comprising about 0.28 to 0.70% by weight of silicon oxide. (2) a precursor material consisting mainly of about 7.43% by weight of barium oxide, about 9.46% by weight of lead oxide, about 55.03% by weight of neodymium oxide, about 28.07% by weight of titanium oxide, and mainly bismuth titanate; Approximately 10.
00% by weight, about 0.10% by weight of manganese carbonate, about 0.25% by weight of niobium pentoxide, about 3.75% by weight of lead oxide, about 0.50% by weight of boron oxide, and about 0.70% by weight of silicon oxide. The ceramic dielectric composition of claim 1 comprising about 15.30% by weight of the ceramic melt composition. (3) Mainly barium oxide about 8.47% by weight, lead oxide about 10.38% by weight, neodymium oxide about 52.02% by weight
, about 29.13% by weight of titanium oxide, and primarily about 10.0% by weight of bismuth titanate, about 0.10% by weight of manganese carbonate, about 0.25% by weight of niobium pentoxide, and about 4% by weight of lead oxide. The ceramic dielectric composition of claim 1, comprising about 13.61% by weight of a ceramic composition comprising about 0.23% by weight of boron oxide, about 0.21% by weight of boron oxide, and about 0.51% by weight of silicon oxide. (4) Mainly barium oxide about 8.47% by weight, lead oxide about 10.38% by weight, neodymium oxide about 52.02% by weight
, about 29.13% by weight of titanium oxide, and primarily about 10.00% by weight of bismuth titanate, about 0.10% by weight of manganese carbonate, about 0.26% by weight of niobium pentoxide, and about 2% by weight of lead oxide. The ceramic dielectric composition of claim 1, comprising about 13.61% by weight of the ceramic composition comprising about 0.65% by weight, about 0.13% by weight boron oxide, and about 0.32% by weight silicon oxide. (5) A multilayer capacitor structure comprising multiple layers of the ceramic composition according to any one of claims 1 to 4, having an internal electrode, the multilayer capacitor being sintered at a temperature of 1140° C. or lower for 1 to 4 hours. structure. (6) The multilayer capacitor structure according to claim 5, wherein the internal electrode comprises about 70% by weight of silver and 30% by weight of palladium.