RU2035778C1 - Mixture of ceramic material for manufacture of high-frequency capacitors with temperature coefficient of capacitance from - 30 10 99 deg 99-991 to +30 10 99-996 deg 99-991 - Google Patents

Abstract

FIELD: radio electronics. SUBSTANCE: ceramic mixture contains solid solution meeting common formula ε and additive. Glass-forming compound of borosilicate (Ba_0,9Sr_0,1)(Nd_0,8Bi_0,2)₂Ti₄O₁₂, where x=-.05-0.70; y=0.30-0.95 in the amount of 1-2 per cent by mass is used as additive. EFFECT: reduction of sintering temperature up to 10-60-1120 C with dielectric permittivity xB₂O₃·ySiO₂=100. 3 tbl

Description

 The invention relates to electronic equipment and can be used in the production of single-layer and multilayer ceramic capacitors with a low sintering temperature, with TKE in the MPO group.

Currently, in the domestic kondensatorostroenii widely used ceramic materials with high sintering temperatures not lower than 1260 ° ^C. High temperature sintering ceramics is the reason that in use expensive Pt and Pd / Pt alloys as internal electrodes of monolithic capacitors. Application of Ag-Pd alloys containing Pd is not more than 30% is possible, provided that the dielectric sintering temperature will not exceed 1120 ° ^C.

 On the other hand, given that the miniaturization of the equipment puts forward the requirements for high specific characteristics of electronic components, the dielectric constant of promising low-temperature high-frequency ceramic materials should not be lower than 80.

Known ceramic material with a dielectric constant of 85-90 for the production of thermostable monolithic type capacitors, protected a. from. N 628134. The specified material has a sintering temperature of ≈1180 ^about C and above. In the manufacture of monolithic capacitors based on it, Pt is used for internal electrodes.

Ceramic materials are known with a sintering temperature of ≈1100 ^о С (Japanese application N 170405, 1982) and with a sintering temperature of 1050 ^о С, patented in the USA (patent No. 4628404). In the manufacture of monolithic capacitors from these materials, an Ag-Pd alloy is used as internal electrodes. Their disadvantage is the low value of ε≈ 50 and 60, respectively.

The closest in technical essence and the achieved result to the claimed composition is the composition of the mixture of ceramic material for high-frequency thermostable capacitors (MPO group) based on a solid solution (Ba _0.9 Sr _0.1 ) (Nd _0.8 Bi _0.2 ) Ti ₄ O ₁₂ protected a. from. N 1536730. In the prototype composition, the effect of lowering the sintering temperature of the solid solution (Ba _0.9 Sr _0.1 ) (Nd _0.3 Bi _0.2 ) ₂ Ti ₄ O _{12 is} achieved by the addition of calcium nitrate Ca (NO ₃ ) ₂ ˙ 4 ˙ H ₂ O and boric acid H ₃ BO ₃ in quantities, wt. 1.88-3.76 and 0.98-1.96, respectively.

The main disadvantage of the prototype is the high sintering temperature of 1120 1220 ^about C, which determines the narrow sintering interval of the monolithic capacitors made on its basis with electrodes based on the alloy 70% Ag 30% Pd. Monolithic capacitors are sintered at a temperature of only 1120 ^{° C,} because above this temperature the melting of the electrodes, and the dielectric below the increased porosity and hence increased tgδ after humidification.

 The purpose of the invention is to reduce the sintering temperature of the material without changing its dielectric characteristics.

Implementation of the claimed invention will reduce the sintering temperature to a level of 1120 ^{° C} and below, to expand the range of sintering temperature, while ensuring that the dielectric constant of the material for capacitors MPO group with electrodes on the basis of an alloy of 70% Ag 30% Pb order of 100.

To achieve the goal, a mixture of ceramic material for high-frequency capacitors with a temperature coefficient of capacitance (0 ± 30) ˙ 10 ^- 6 deg ^-1 contains a solid solution (Ba _0.9 Sr _0.1 ) (Nd _0.8 Bi _0.2 ) ₂ Ti ₄ O ₁₂ and the additive xB ₂ O ₃ ˙ ySiO ₂ , where x 0.05-0.70; y 0.30-0.95 in the following ratio of components, wt. Solid solution (Ba _0.9 Sr _0.1 ) (Nd _0.8 Bi _0.2 ) Ti ₄ O ₁₂ 98.0-99.0 x B ₂ O ₃ ˙ ySiO ₂ (where x 0.05-0, 70; y 0.30-0.95) 1.0-2.0.

Comparative analysis with the prototype allows us to conclude that the claimed composition of the charge differs from the known introduction of additives x B ₂ O ₃ ˙ ySiO ₂ at x 0.05-0.70; y 0.30-0.95 and a change in the content in the charge of the specified solid solution. To date, we do not know the same or identical technical solution to the claimed one, which allows us to consider the proposed composition meeting the criterion of "novelty."

The presence of semi-colloidal ceramic solution borosilicate glass is uniformly distributed in the matrix of the ceramic powder leads to the fact that during a single-phase crystal structure sintering bariylantanoidnogo tetratitanata formed at a temperature of ^about 1060 C; while ε and tanδ remain unchanged.

 Thus, the proposed mixture of ceramic material for thermostable high-frequency capacitors with TKE in the MPO group as a set of essential features makes an inextricable causal relationship with the achieved technical result and meets the criterion of "inventive step".

 The validity of the claimed ratio of ingredients of the composition of the material is confirmed by the following examples and the test report.

Indicated in the table. 1, the ratios between x and y were selected based on the fact that during the heat treatment, borosilicate glasses of the B ₂ O ₃ ˙ SiO ₂ system should be formed in the amount of: 1% (example 1), 2% (example II), 1.5% ( Example III). In the B ₂ O ₃ —SiO _{2 system,} both oxides in the molten state are completely mixed and at a ratio of B ₂ O ₃ and SiO ₂ of 5 mol%. B ₂ O ₃ 95 mol. SiO ₂ up to 70 mol. B ₂ O ₃ 30 mol. SiO ₂ provide a decrease in the sintering temperature of the solid solution (Ba _0.9 Sr _0.1 ) (Nd _0.8 Bi _0.2 ) ₂ ˙ Ti ₄ O ₁₂ . In the table. 1 examples are considered for the following compositions of borosilicate glasses: 5 mol. B ₂ O ₃ 95 mol. SiO ₂ (Example A); 30 mol. B ₂ O ₃ 70 mol. SiO ₂ (example B); 50 mol. In ₂ About ₃ 50 mol. SiO ₂ (Example B); 70 mol. In ₂ O ₃ -30 mol. SiO ₂ (example D).

The solid solution (Ba _0.9 Sr _0.1 ) (Nd _0.8 Bi _0.2 ) ₂ Ti ₄ O ₁₂ is commercially available and is supplied in accordance with current specifications. Additives that form borosilicate glasses during the firing process are prepared in the form of a mixture of solutions of boric acid in water and an aqueous-alcoholic solution of silica ether.

___→

+
Из уравнения видно, что для получения Ir B₂O₃ требуется 123,6/69,6 1,77 борной кислоты. Согласно примеру I(В) при введении 1 мас. В₂О₃ ˙SiO₂ соотношение оксидов должно быть следующим: 0,537 мас. В₂О₃ и 0,463 мас. SiO₂.Preparation of solutions of H ₃ VO ₃ and (C ₂ H ₅ O) ₄ Si according to example I (B)

___ →

+
From the equation it is seen that to obtain Ir B ₂ O ₃ requires 123.6 / 69.6 of 1.77 boric acid. According to example I (B) with the introduction of 1 wt. In ₂ About ₃ ˙ SiO _{2 the} ratio of oxides should be as follows: 0.537 wt. In ₂ About ₃ and 0.463 wt. SiO ₂ .

Thus, to prepare a solution of boric acid in water, it is necessary to take: 0.537 x 1.77 0.95 wt. (H ₃ IN ₃ ) to get in the cake 0.537 wt. B ₂ About ₃ .

___→ H₄SiO₄ __→ S

то для получения Ir SiO₂ необходимо взять

3,467 кг (С₂Н₅О)₄Si.2) Given that during heat treatment, silica ether is completely hydrolyzed and then converted to silica by the chain:
(C ₂ H

___ → H ₄ SiO ₄ __ → S

then to obtain Ir SiO ₂ you must take

3.467 kg (C ₂ H ₅ O) ₄ Si.

To initiate the hydrolysis reaction of silicoethyl ether, it is necessary to prepare a water-alcohol solution in the following ratio of components: 100 ml of silica ether, 45 ml of 85% ethyl alcohol, 15 ml of water. In the solution thus obtained, silica ether and orthosilicic acid are in equilibrium, and the amount of SiO ₂ in I g of such a solution will be 0.189 g.

Thus, to obtain 0.467 wt. SiO ₂ , it is necessary to take a colloidal solution of silicic acid 0.463 / 0.186 2.49 g

 The calculated amount of boric acid is dissolved in water and mixed with a water-alcohol solution of silica ether, after which a mixture of ceramic material is prepared.

Preparation of a mixture of ceramic material. The solid solution (Ba _0.9 Sr _0.1 ) (Nd _0.8 Bi _0.2 ) ₂ Ti ₄ O _{12 is} mixed with the additive solutions by the wet method in a ball mill or KSK-G type. Slip drying is carried out at a temperature of 80 ^about C and calcined at a temperature of 500-700 ^about C.

Samples with a diameter of 15 mm and h≈ 2 mm at P 1000 kg / cm ^{2 are} pressed from the prepared material. Calcination of the samples produced in the temperature range 1060-1120 ^{° C,} then metallized paste and silver-silver vzhigayut at 800-820 ° ^C.

 The electrical properties of the proposed material and the material of the prototype are presented in table.2.

As can be seen from the table. 2, the positive effect is only achieved in the claimed range of concentrations of the components at a certain ratio of oxides in the system of B ₂ O ₃ ˙SiO _2: dielectric permeability and tgδ material remain unchanged, the sintering temperature is lowered to 1060 ° ^C.

The ratio of the ingredients corresponding to their transcendental values does not ensure the achievement of the desired goal, since a decrease in the content of these additives (Example IV) does not have the effect of lowering the sintering temperature of the ceramic material, and an increase in their content (Example V) leads to a decrease in the dielectric constant and an increase in the ceramic tanδ material. On the other hand, a change in the ratio of oxides in the borosilicate glass additive system, corresponding to their transcendental ratios, namely, a decrease in the amount of B ₂ O ₃ less than 5 mol. and, accordingly, an increase in the amount of SiO ₂ more than 95 mol. (example D), as well as reducing the amount of SiO ₂ less than 30 mol. and an increase in ₂ About ₃ over 70 mol. (Example E) leads to the fact that during the heat treatment there is no complete shift of the oxides, which leads to stratification of the melt and, as a consequence, to the formation of impurity phases during firing of ceramics, as a result of which the effect of lowering the sintering temperature is not achieved and the tanδ of sintered samples increases.

 Various types of monolithic capacitors with TKE according to the MPO group (K10-43, K10-47, K10-50, K10-60, K10-70, etc.) can be made from the proposed ceramic material. The monolithic bags are assembled from a ceramic film with pressed electrodes based on 70% Ag 30 Pd alloy.

 In the table. 3 shows the electrical properties of monolithic capacitors K10-47 of the proposed material and the prototype material with electrodes based on 70% Ag 30 Pd alloy.

The electrical parameters of the capacitors of the proposed material satisfy OST V II-0030-84. It is significant that capacitors from the proposed ceramic material with electrodes based on 70% Ag 30% Pd alloy have a sintering temperature range of 1060-1120 ^о С, while capacitors from the prototype material can be fired with electrodes from Ag-Pd only the alloy at a temperature of ^about 1120 C, since at a temperature of ¹¹⁰⁰ C sintered insulator is not sufficient (the porosity of 7.8%), and at a temperature of ^about 1140 C electrode is 70% Ag 30% Pd already begins to fuse.

 Thus, the advantages of the claimed invention over the prototype are to reduce the sintering temperature of the ceramic material and to expand the sintering temperature range of monolithic capacitors made on its basis with electrodes from 70% Ag 30% Pd alloy, which leads to a significant increase in the number of suitable products in the production of capacitors from the proposed ceramic material compared to the prototype material.

Claims (1)

MIXTURE OF CERAMIC MATERIAL FOR HIGH-FREQUENCY CAPACITORS WITH TEMPERATURE CAPACITY COEFFICIENT FROM -30 · 10 ^-6 deg ^-1 to +30 · 10 ^-6 deg ^-1 , containing a solid solution of the formula (Ba _{0 , 9} Sr _{0 , 1} ) (Nd _{0 , 8} Bi _{0 , 2} ) ₂ · Ti ₄ O _{1 2} and an additive, characterized in that the glass-forming borosilicate compound xB ₂ O ₃ · ySiO ₂ , where x 0.05 ^o C 0.70, y 0.30 ^o C 0.95, in the following ratio of components, wt. Solid solution (Ba _{0 , 9} Sr _{0 , 1} ) (Nd _{0 , 8} Bi _{0 , 2} ) ₂ Ti ₄ O _{1 2}
98 99
Glass-forming compound of borosilicate xB ₂ O ₃ · ySiO ₂ 1 2

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