CN103992107B - A kind of low-loss medium material for multilayer ceramic capacitors - Google Patents

Abstract

The invention discloses a low-loss multilayer ceramic capacitor dielectric material, which uses BaTiO ₃ powder as the base material, and on this basis, 0.4-0.6% of MnCO ₃ and 0.6-1.8% of (NiO) ₁ are added. _-x (NbO _2.5 ) _x , wherein x=0.6～0.8; 0.5～3.0% of CaZrO ₃ and 4～7% of glass flux; the (NiO) _1-x (NbO _2.5 ) _x compound is NiO and Nb ₂ O ₅ in a molar ratio of 1-x:x/2, where x=0.6-0.8. Through the addition of manganese carbonate, the present invention can effectively improve the ceramic microstructure, improve the dielectric properties of the ceramics, reduce the dielectric loss, and the room temperature loss value reaches below 0.5% (tanδ<0.5%); the present invention has excellent dielectric properties Electrical properties: In the temperature range of -55°C to 150°C, the capacitance change rate is within ±15%, and it has a relatively high room temperature dielectric constant (~2700).

Description

A Dielectric Material for Low Loss Multilayer Ceramic Capacitors

technical field

The invention belongs to a ceramic composition characterized by components, in particular to a low-loss and temperature-stable X8R multilayer ceramic capacitor dielectric material and a preparation method thereof

Background technique

Chip multilayer ceramic capacitors (Multilayer Ceramic Capacitor, referred to as MLCC) as basic electronic components, in addition to smart phones, tablet computers, radio and television, mobile communications, home computers, household appliances, measuring instruments, medical equipment and other civilian products and consumer electronics In addition to being widely used, it has a wide range of applications in aerospace, tank electronics, military mobile communications, weapon warhead control, military signal monitoring and other military electronic equipment, as well as oil exploration and other industries. Barium titanate (BaTiO ₃ )-based temperature-stable MLCC dielectric material has been a research hotspot because it is harmless to the environment. At present, EIAX7R (-55℃～125℃, ΔC/C _25℃ ≤±15 %) Dielectric material. With the rapid development of MLCC, the research on dielectric materials for MLCC has put forward higher requirements, that is, to maintain stable dielectric properties in higher temperature environments. For example, in summer, the temperature in the engine compartment of a car will reach 130 °C Above, at this time, the X7R dielectric material is difficult to meet the actual needs. Therefore, the development of dielectric materials for X8R (-55°C ~ 150°C, ΔC/C _25°C ≤ ± 15%) type MLCC has very important practical significance.

However, within the working temperature range, although the dielectric capacity change rate of this series of ceramic capacitors can meet the requirements of X8R, the dielectric loss at room temperature is still more than 1%, which affects the service life and stability of components and restricts their use in a certain range. Applications in some aspects, such as low-loss EMI filter multilayer ceramic capacitors, so reducing the loss of ceramic capacitors has become the key to improving capacitor performance.

Contents of the invention

The purpose of the present invention is to overcome the defect that the capacity change rate of the ceramic capacitor medium in the prior art can reach the requirement of X8R, but its dielectric loss is still above 1%, and cannot fully adapt to the needs of some special occasions, and provides a Medium-temperature sintered X8R type multilayer ceramic capacitor dielectric material with low loss (tanδ≤0.5%) and relatively high dielectric constant and its preparation method. Book

The present invention is realized through the following technical solutions.

A low-loss multilayer ceramic capacitor dielectric material, with BaTiO ₃ powder as the base material, on this basis, an additional mass percentage of 0.4-0.6% MnCO ₃ ; 0.6-1.8% (NiO) _1-x (NbO _2.5 ) _x , where x=0.6-0.8; 0.5-3.0% CaZrO ₃ and 4-7% glass flux;

The (NiO) _1-x (NbO _2.5 ) _x compound is synthesized by NiO and Nb ₂ O ₅ in a molar ratio of 1-x:x/2, where x=0.6-0.8;

The _CaZrO3 is synthesized by CaCO3 and ZrO2 in a molar ratio of ₁ : ₁ ;

The raw material components and mass percent contents of the glass flux are: 17% of TiO ₂ , 34% of H ₃ BO ₃ , 26% of ZnO and 23% of Bi ₂ O ₃ ;

The preparation method of the low-loss multilayer ceramic capacitor dielectric material has the following steps:

(1) Synthesis of (NiO) _1-x (NbO _2.5 ) _x compounds, where x=0.6～0.8

Mix NiO and Nb ₂ O ₅ in a molar ratio of 1-x:x/2, where x=0.6~0.8, mix the raw materials with deionized water, ball mill for 4 hours, dry at 120°C, and pass through a 40-mesh sieve. Calcined at 1000°C, ball milled again for 6 hours, dried, and passed through an 80-mesh sieve to obtain (NiO) _1-x (NbO _2.5 ) _x , where x=0.6～0.8;

(2) Synthesis of CaZrO ₃

Mix CaCO ₃ and ZrO ₂ in a molar ratio of 1:1, mix the raw materials with deionized water, ball mill for 4 hours, dry at 120°C, pass through a 40-mesh sieve, and calcinate at 1000°C to obtain CaZrO ₃ ;

(3) Synthetic glass flux

According to mass percentage, 17% of TiO ₂ , 34% of H ₃ BO ₃ , 26% of ZnO and 23% of Bi ₂ O ₃ are fully mixed, melted, quenched, ground, and passed through a 200-mesh sieve to prepare Obtain glass flux;

(4) Using BaTiO ₃ as the base material, add the following components in mass percentage: 0.4-0.6% of MnCO ₃ , 0.6-1.8% of (NiO) _1-x (NbO _2.5 ) _x , where x=0.6- 0.8; 0.5-3.0% CaZrO ₃ and 4-7% glass flux, mix the prepared raw materials with deionized water, ball mill for 4-8 hours, add 7% binder after drying, 80 mesh sieve granulation;

(5) Press the granulated powder in step (4) into a green body, after debinding, sinter at 1150° C., and keep warm for 3 hours to obtain a low-loss multilayer ceramic capacitor dielectric material.

The preferred addition amount of the MnCO ₃ is 0.5wt%.

The green body in the step (5) is a round wafer green body with a diameter of Ф15×1˜1.3 mm.

The green body in the step (5) is heated to 550° C. for debinding after 3.5 hours, then heated to 1150° C. for 1 hour for sintering, and kept for 3 hours.

The beneficial effects of the present invention are as follows:

1. The multilayer ceramic capacitor dielectric material of the present invention can effectively improve the ceramic microstructure through the addition of manganese carbonate, promote the dielectric properties of ceramics, reduce dielectric loss, and the room temperature loss value reaches below 0.5% (tanδ<0.5%);

2. The multilayer ceramic capacitor dielectric material of the present invention has excellent dielectric properties: in the temperature range of -55 ℃ to 150 ℃, the rate of change of capacitance is within ± 15%, and has a higher room temperature dielectric constant (～ 2700).

Detailed ways

The present invention will be described in further detail below in conjunction with specific examples.

Example 1

First, weigh and analyze 2.2410g NiO and 9.3033g Nb ₂ O ₅ of pure grade (≥99%) with an electronic balance, mix them, and use deionized water as the ball milling medium. After ball milling for 4 hours, dry at 120°C and pass through 40 mesh to divide the samples. sieve, calcined at 1000°C to obtain (NiO) _0.3 (NbO _2.5 ) _0.7 compound, ball milled again for 6 hours, dried at 120°C, passed through an 80-mesh sieve for later use;

Then mix 22.3291g CaCO ₃ and 27.5114g ZrO ₂ , use deionized water as the ball milling medium, dry at 120°C after ball milling for 4 hours, pass through a 40-mesh sieve, and calcinate at 1000°C to obtain CaZrO ₃ ;

Then 17gTiO ₂ , 34gH ₃ BO ₃ , 26gZnO and 23gBi ₂ O ₃ were fully mixed, melted, quenched, ground, and passed through a 200-mesh sieve to obtain a glass flux.

Mix 50gBaTiO ₃ , 0.25gMnCO ₃ , 0.45g (NiO) _0.3 (NbO _2.5 ) _0.7 , 0.5gCaZrO ₃ and 2.5g glass flux with deionized water, ball mill for 4 hours, dry and add 7% paraffin wax , passed through an 80-mesh sieve for granulation.

Forming and sintering:

(1) Press the granulated powder into a Ф15×1.2mm green disc at 3MPa, raise the temperature to 550°C for 3.5 hours to remove the glue, then raise the temperature to 1150°C for 1 hour for sintering, and keep it warm for 3 hours. A low-loss multilayer ceramic capacitor dielectric material is obtained.

The upper and lower surfaces of the obtained product were uniformly coated with silver paste, and the electrode was prepared by firing at 850°C, and the sample to be tested was prepared to test the dielectric properties and TC characteristics.

The specific raw material ratio of Examples 1-5 is detailed in Table 1, and other manufacturing processes of Examples 2-5 are the same as Example 1.

Table 1

Test method and detection equipment of the present invention are as follows:

(1) Dielectric performance test (AC test signal: frequency is 1kHz, voltage is 1V)

Use the HEWLETTPACKARD4278A capacitance tester to test the capacitance C and loss tanδ of the sample, and calculate the dielectric constant of the sample. The calculation formula is:

$\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 14.4</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; d</span>}}{{\mathrm{<span\; class="notranslate">\; D.</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

(2) TC characteristic test

Use GZ-ESPECMPC-710P high and low temperature cycle thermostat, HM27002 capacitor C-T/V characteristic special tester and HEWLETTPACKARD4278A to test. Measure the capacitance of the sample in the temperature range of -55°C to 150°C, and use the following formula to calculate the capacitance change rate:

Table 2 shows the dielectric properties of the dielectric materials of the disc-shaped multilayer ceramic capacitors in Examples 1-5.

Table 2

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 (4)

1. A low-loss multilayer ceramic capacitor dielectric material, with BaTiO ₃ powder as the base material, on this basis, an additional mass percentage of 0.4 to 0.6% MnCO ₃ ; 0.6 to 1.8% (NiO) _1-x (NbO _2.5 ) _x , where x=0.6-0.8; 0.5-3.0% CaZrO ₃ and 4-7% glass flux; The (NiO) _1-x (NbO _2.5 ) _x compound is synthesized by NiO and Nb ₂ O ₅ in a molar ratio of 1-x:x/2, where x=0.6-0.8; The _CaZrO3 is synthesized by CaCO3 and ZrO2 in a molar ratio of ₁ : ₁ ; The raw material components and mass percent contents of the glass flux are: 17% of TiO ₂ , 34% of H ₃ BO ₃ , 26% of ZnO and 23% of Bi ₂ O ₃ ; The preparation method of the low-loss multilayer ceramic capacitor dielectric material has the following steps: (1) Synthesis of (NiO) _1-x (NbO _2.5 ) _x compounds, where x=0.6～0.8 Mix NiO and Nb ₂ O ₅ in a molar ratio of 1-x:x/2, where x=0.6~0.8, mix the raw materials with deionized water, ball mill for 4 hours, dry at 120°C, and pass through a 40-mesh sieve. Calcined at 1000°C to obtain (NiO) _1-x (NbO _2.5 ) _x , where x=0.6~0.8; ball mill for 6 hours again, dry, pass through 80-mesh sieve, (2) Synthesis of CaZrO ₃ Mix CaCO ₃ and ZrO ₂ in a molar ratio of 1:1, mix the raw materials with deionized water, ball mill for 4 hours, dry at 120°C, pass through a 40-mesh sieve, and calcinate at 1000°C to obtain CaZrO ₃ ; (3) Synthetic glass flux According to mass percentage, 17% of TiO ₂ , 34% of H ₃ BO ₃ , 26% of ZnO and 23% of Bi ₂ O ₃ are fully mixed, melted, quenched, ground, and passed through a 200-mesh sieve to prepare Obtain glass flux; (4) Using BaTiO ₃ as the base material, add the following components in mass percentage: 0.4-0.6% of MnCO ₃ , 0.6-1.8% of (NiO) _1-x (NbO _2.5 ) _x , where x=0.6- 0.8; 0.5-3.0% CaZrO ₃ and 4-7% glass flux, mix the prepared raw materials with deionized water, ball mill for 4-8 hours, add 7% binder after drying, 80 mesh sieve granulation; (5) Press the granulated powder in step (4) into a green body, after debinding, sinter at 1150° C., and keep warm for 3 hours to obtain a low-loss multilayer ceramic capacitor dielectric material. 2. A kind of low-loss multilayer ceramic capacitor dielectric material according to claim ₁ , characterized in that, the preferred addition amount of said MnCO is 0.5wt%. 3 . The low-loss multilayer ceramic capacitor dielectric material according to claim 1 , wherein the green body in the step (5) is a round green body of Φ15×1˜1.3 mm. 4 . 4. A kind of low-loss multilayer ceramic capacitor dielectric material according to claim 1, characterized in that, the green body in the step (5) is heated to 550 ° C for debinding after 3.5 hours, and then raised to 1150 °C after 1 hour. ℃ sintering, heat preservation for 3 hours.