CN104311000A - Preparation method of ultrahigh-working-temperature X-R multilayer ceramic capacitor dielectric - Google Patents

Abstract

The invention discloses a method for preparing an ultra-high working temperature XR type multilayer ceramic capacitor medium. Firstly, Na ₂ CO ₃ , Bi ₂ O ₃ , and TiO ₂ are mixed according to a mass ratio of 3:15:10, ball milled, dried, After calcination, Na _0.5 Bi _0.5 TiO ₃ powder is obtained; the powder is mixed with BaTiO ₃ and Nb ₂ O ₅ at a mass ratio of 0.5-1.5:3-6:0.1-2, and the frit is obtained after pre-calcination; another 30wt% raw material ZnO + 20wt% TiO ₂ + 25wt% SiO ₂ + 25wt% H ₃ BO ₃ for batching to obtain glass powder; based on 100g of frit, add 2-8g ZnO, 2-8g glass powder and 0.2-1.0g of rare earth Oxide RE ₂ O ₃ ingredients (RE is one or more of lanthanum La, praseodymium Pr, neodymium Nd, terbium Tb, holmium Ho or erbium Er), ball milling, drying, granulation, sieving and pressing to produce Blank; the green body is sintered at 1100-1150°C, and then fired and infiltrated to prepare electrodes, and the XR type multilayer ceramic capacitor dielectric is obtained. The invention has an ultra-wide working temperature range (-55°C to 450°C), high dielectric constant (>2400), small capacity change rate (<±15%), medium temperature sintering (<1150°C), and no toxic substances , and the cost of raw materials is low, and has a good application prospect.

Description

A preparation method of ultra-high working temperature X-R type multilayer ceramic capacitor dielectric

technical field

The present invention relates to a ceramic composition characterized by components, in particular to a lead-free, high dielectric constant, high-temperature stable ceramic capacitor dielectric with BaTiO ₃ -Na _0.5 Bi _0.5 TiO ₃ -Nb ₂ O ₅ as the matrix and its preparation method.

Background technique

In recent years, the development trend of dielectric materials for multilayer ceramic capacitors has been to improve their overall performance, and to expand their operating temperature range on the premise of ensuring their high reliability. X7R (working temperature range is -55~125°C), X8R (working temperature range is -55~150°C), X9R (working temperature range is -55~200°C) standard dielectric materials. However, in the field of automotive electronics, MLCC (Chip Multilayer Ceramic Capacitor) has a high operating temperature. For example, on the ABS (Anti-Block System, anti-lock braking system) sensor of the automobile, the operating temperature reaches 150-250 ° C. The working temperature of medium sensors reaches 200-300°C, and the use environment in aerospace, geological exploration and other fields is more harsh. Obviously, the traditional X7R, X8R and X9R cannot meet the demand. In order to save production costs, silver-palladium alloy or pure silver electrodes must be used, so the realization of medium temperature sintering is an important research direction of dielectric materials in recent years. With the development of communication technology, electronic components are developing toward miniaturization and miniaturization. In order to realize the miniaturization of the capacitor, improving the dielectric constant of the dielectric material is the key to solving the problem. Therefore, it is imminent to develop a medium temperature sintering, high dielectric constant, high temperature stable ceramic capacitor dielectric material.

Contents of the invention

The purpose of the present invention is to overcome the defect that the traditional X7R, X8R and X9R multilayer ceramic capacitors cannot meet the more demanding environment, and to provide a low sintering temperature, high dielectric constant, good temperature stability, high upper limit operating temperature, Ultra-high operating temperature X-R type multilayer ceramic capacitor dielectric with low dielectric loss.

The present invention is realized through the following technical solutions.

A method for preparing an ultra-high working temperature X-R type multilayer ceramic capacitor dielectric, comprising the following steps:

(1) Mix Na ₂ CO ₃ , Bi ₂ O ₃ , and TiO ₂ in a mass ratio of 3:15:10, mix with deionized water and ball mill for 6 hours, dry and calcinate at 800°C to obtain Na _0.5 Bi _0.5 TiO ₃ powder;

(2) Mix the Na _0.5 Bi _0.5 TiO ₃ powder prepared in step (1) with BaTiO ₃ and Nb ₂ O ₅ at a mass ratio of 0.5-1.5:3-6:0.1-2, then mix with deionized water and ball mill for 4 hours , pre-fired at 1000°C after drying to obtain a frit;

(3) In addition, according to the mass percentage content of the raw materials, 30wt% ZnO + 20wt% TiO ₂ + 25wt% SiO ₂ + 25wt% H ₃ BO ₃ were mixed, mixed with alcohol and ball milled for 4 hours, then dried, melted and quenched , grind and sieve to obtain glass powder;

(4) The frit obtained in step (2) is calculated as 100g, plus 2-8g ZnO, 2-8g glass powder, and 0.2-1.0g rare earth oxide RE ₂ O ₃ ingredients; the rare earth oxide RE In ₂ O ₃ , RE is one or more of lanthanum La, praseodymium Pr, neodymium Nd, terbium Tb, holmium Ho or erbium Er; mix with deionized water and ball mill for 4 hours, then dry;

(5) adding 7% paraffin wax granulation to the raw material dried in step (4), then passing through a 1000 holes/cm ² sampling sieve, and pressing it into a green body;

(6) Heat up the green compact pressed in step (5) to 550°C for 3.5 hours to discharge wax, then heat up to 1100-1150°C for 1-5 hours for sintering, and keep warm for 0.5-3 hours.

(7) Evenly coat the upper and lower surfaces of the obtained sample with silver paste, prepare electrodes by firing at 750°C, and obtain a multilayer ceramic capacitor dielectric with a high dielectric constant and an ultra-wide operating temperature range;

(8) Test the dielectric properties of the multilayer ceramic capacitor dielectric.

The drying temperature of step (1) or step (2) or step (4) is 120°C.

The step (5) is pressing into a green body under a pressure of 4-10 MPa.

The ultra-high working temperature X-R type ceramic capacitor medium disclosed by the invention is a kind of ultra-wide working temperature range (-55°C-450°C), high dielectric constant (>2400), and small capacity change rate (<±15°C). %), medium-temperature sintered (<1150°C) multilayer ceramic capacitor dielectric. The invention does not contain toxic substances, has low cost of raw materials, and has good application prospects.

Detailed ways

The raw materials used in the present invention are analytically pure raw materials, and the present invention will be further described below through specific examples.

Na ₂ CO ₃ , Bi ₂ O ₃ , and TiO ₂ were mixed according to the mass percentage of 3:15:10, mixed with deionized water and ball-milled for 6 hours, dried, and calcined at 800°C to obtain Na _0.5 Bi _0.5 TiO ₃ powder; Na _0.5 Bi _0.5 TiO ₃ powder was mixed with BaTiO ₃ and Nb ₂ O ₅ at a mass ratio of 1:4:0.12, mixed with deionized water and ball milled for 4 hours, dried and pre-calcined at 1000°C to obtain a frit; Based on 100g, add 2~8g ZnO, 2~8g glass powder, 0.2~1.0g rare earth oxide RE ₂ O ₃ , in the rare earth oxide RE ₂ O ₃ , RE is La, Pr, Nd, Tb, Ho , Er, one or more ingredients, the composition and mass percentage of the glass powder raw materials are: 30% ZnO, 22% TiO ₂ , 25% SiO ₂ , 25% H ₃ BO ₃ , the above raw materials and deionized Mix with water and ball mill for 4 hours and dry; add paraffin wax with a mass percentage of 7% to the dried raw materials, and then pass through a 1000 hole/cm ² sampling sieve, and press it into a green body under a pressure of 6Mpa; the pressed raw material The billet is heated to 550°C for 3.5 hours to discharge wax, then heated to 1150°C for 4 hours for sintering, and kept for 0.5 to 3 hours; the upper and lower surfaces of the prepared product are evenly coated with silver paste, and the electrode is prepared by firing at 800°C. Ultra-high operating temperature XR type multilayer ceramic capacitor dielectric.

The main process parameters and dielectric properties of specific embodiments of the present invention are shown in Table 1.

Table 1

The working temperature ranges of the above-mentioned embodiments all meet the working requirements of -55°C to 450°C.

The present invention is not limited to the above-described embodiments, and changes in many details are possible without departing from the scope and spirit of the present invention.

Claims (3)

1. A preparation method for an ultra-high operating temperature X-R type multilayer ceramic capacitor medium has the following steps: (1) Mix Na ₂ CO ₃ , Bi ₂ O ₃ , and TiO ₂ in a mass ratio of 3:15:10, mix with deionized water and ball mill for 6 hours, dry and calcinate at 800°C to obtain Na _0.5 Bi _0.5 TiO ₃ powder; (2) Mix the Na _0.5 Bi _0.5 TiO ₃ powder prepared in step (1) with BaTiO ₃ and Nb ₂ O ₅ at a mass ratio of 0.5-1.5:3-6:0.1-2, then mix with deionized water and ball mill for 4 hours , pre-fired at 1000°C after drying to obtain a frit; (3) In addition, according to the mass percentage content of the raw materials, 30wt% ZnO + 20wt% TiO ₂ + 25wt% SiO ₂ + 25wt% H ₃ BO ₃ were mixed, mixed with alcohol and ball milled for 4 hours, then dried, melted and quenched , grind and sieve to obtain glass powder; (4) The frit obtained in step (2) is calculated as 100g, plus 2-8g ZnO, 2-8g glass powder, and 0.2-1.0g rare earth oxide RE ₂ O ₃ ingredients; the rare earth oxide RE In ₂ O ₃ , RE is one or more of lanthanum La, praseodymium Pr, neodymium Nd, terbium Tb, holmium Ho or erbium Er; mix with deionized water and ball mill for 4 hours, then dry; (5) adding 7% paraffin wax granulation to the raw material dried in step (4), then passing through a 1000 holes/cm ² sampling sieve, and pressing it into a green body; (6) Heat up the green compact pressed in step (5) to 550°C for 3.5 hours to discharge wax, then heat up to 1100-1150°C for 1-5 hours for sintering, and keep warm for 0.5-3 hours. (7) Evenly coat the upper and lower surfaces of the obtained sample with silver paste, prepare electrodes by firing at 750°C, and obtain a multilayer ceramic capacitor dielectric with a high dielectric constant and an ultra-wide operating temperature range; (8) Test the dielectric properties of the multilayer ceramic capacitor dielectric. 2. the preparation method of a kind of ultra-high working temperature X-R type multilayer ceramic capacitor medium according to claim 1, is characterized in that, the drying temperature of described step (1) or step (2) or step (4) is 120°C. 3 . The method for preparing a medium of an ultra-high working temperature X-R multilayer ceramic capacitor according to claim 1 , wherein the step (5) is to press the green body under a pressure of 4-10 MPa. 4 .