1. A piezoelectric ceramic low-temperature co-firing sintering agent is characterized by comprising PZT ceramic powder, low-melting mixed glass powder and terpineol; the mass ratio of the PZT ceramic powder to the low-melting-point mixed glass powder is 1-5: 9-5; the mass ratio of the PZT ceramic powder to the low-melting-point mixed glass powder to the terpineol is 2: 1.

2. The low-temperature co-fired piezoelectric ceramic sintering agent according to claim 1, wherein the low-melting mixed glass powder comprises the following components in parts by weight: SiO 2₂ 20~50%，Al₂O₃ 0~5.0%，B₂O₃ 15~30%, Na₂O 1~10z%, K₂O 0~2.0%, Li₂O 1~5%, CaO 0~5%, MgO 1~5%，ZnO 15~25%, ZrO₂ 1~5%, TiO₂ 0~2.0%, Bi₂O₃ 0~5.0%。

3. The low-temperature co-fired piezoelectric ceramic sintering agent according to claim 2, wherein the low-melting mixed glass powder comprises the following components in parts by weight: SiO 2₂ 27.0%，Al₂O₃ 2.0%，B₂O₃ 30.0%，Na₂O 5.0%，K₂O 2.0%，LiO₂3.0%，CaO 3.0%，MgO 1.0%，ZnO19.0%，ZrO₂3.0%，Bi₂O₃5.0%。

4. The low-temperature co-fired piezoelectric ceramic sintering agent according to claim 3, wherein the mass ratio of the PZT ceramic powder to the low-melting-point mixed glass powder is 1: 9.

5. A method for preparing a low-temperature co-fired sintering agent for piezoelectric ceramics as defined in claim 1, wherein the low-temperature co-fired sintering agent for piezoelectric ceramics is prepared by mixing PZT ceramic powder, low-melting mixed glass powder and terpineol in a certain proportion.

6. The piezoelectric ceramic low-temperature co-fired sintering agent as defined in any one of claims 1 to 5 is applied to piezoelectric ceramic integrated sintering.

7. The application of the low-temperature co-fired sintering agent for the piezoelectric ceramics according to claim 6, wherein the sintering temperature of the low-temperature co-fired sintering agent for the piezoelectric ceramics during the integral sintering of the piezoelectric ceramics is 700-750 ℃.

Background

The piezoelectric ceramic is an important branch of electronic information materials, has wide application in the fields of aerospace, industry, medical treatment, civil use and national defense, and the application range of the piezoelectric ceramic is gradually expanded along with the continuous progress of the piezoelectric ceramic materials and related technologies. PZT-based piezoelectric ceramics have the characteristics of high Curie temperature, high piezoelectric constant, excellent mechanical property, good stability and the like, and are in leading position in the field of piezoelectric ceramic materials at present. The sintering temperature of PZT is about 1200 ℃, lead oxide (volatilization temperature is 800 ℃) in the components is volatile at high temperature, so that the components deviate from the stoichiometric ratio, the piezoelectric property of the material is influenced, the environment is polluted, and the problem can be solved if the sintering can be carried out before PbO obviously volatilizes.

The low-temperature co-fired ceramic technology is a novel electronic packaging technology developed by the United states Huss company in 1982, is widely applied to various aspects such as base stations, automotive electronics, Bluetooth, aerospace and the like at present, and has attracted people's attention in research, but has not been reported when being applied to integrated sintering among piezoelectric ceramic materials so that the piezoelectric ceramic forms an integrated material.

At present, low-temperature co-fired materials are classified into three categories: a glass ceramics system: such as Al₂O₃ ⁺A glass system having a low dielectric constant (ε r ≦ 10); amorphous glass system: fully mixing the oxides for forming the glass, and calcining at 800-950 ℃; glass + ceramic composite system: this is the most common LTCC material at present, i.e. low melting point glass phase is added to the ceramic, and the glass softens and the viscosity decreases during sintering, so that the sintering temperature can be reduced. In addition to the matrix material forming the glass or ceramic, some additives, such as sintering aid, etc., are usually added to the system to improve the devitrification ability, sintering property, electrical properties, etc. of the system.

Disclosure of Invention

The invention provides a low-temperature co-fired ceramic sintering agent and a preparation method and application thereof, aiming at the problems of high sintering temperature, poor electrical and mechanical properties and poor interface coupling property of a bonding agent for bonding and integrating ceramic materials in the prior art, wherein the piezoelectric ceramic low-temperature co-fired sintering agent prepared by the method has the same or similar thermal expansion coefficient with the piezoelectric ceramic materials, can realize integrated sintering, and simultaneously reduces the sintering temperature.

The invention is realized by the following technical scheme:

a piezoelectric ceramic low-temperature co-firing sintering agent comprises PZT ceramic powder, low-melting mixed glass powder and terpineol; the mass ratio of the PZT ceramic powder to the low-melting-point mixed glass powder is 1-5: 9-5; the mass ratio of the PZT ceramic powder to the low-melting-point mixed glass powder to the terpineol is 2: 1.

Further, the low-melting-point mixed glass powder comprises the following components in parts by weight: SiO 2₂ 20~50%，Al₂O₃0~5.0%，B₂O₃15~30%,Na₂O 1~10z%,K₂O 0~2.0%,Li₂O 1~5%,CaO0~5%,MgO 1~5%，ZnO 15~25%,ZrO₂ 1~5%,TiO₂ 0~2.0%,Bi₂O₃ 0~5.0%。

Further, the low-melting-point mixed glass powder comprises the following components in parts by weight: SiO 2₂ 27.0%，Al₂O₃2.0%，B₂O₃ 30.0%，Na₂O 5.0%，K₂O 2.0%，LiO₂3.0%，CaO 3.0%，MgO 1.0%，ZnO19.0%，ZrO₂3.0%，Bi₂O₃5.0%

Further, the mass ratio of the PZT ceramic powder to the low-melting-point mixed glass powder is 1: 9.

In the invention, the preparation method of the piezoelectric ceramic low-temperature co-fired sintering agent comprises the following steps: mixing PZT ceramic powder, low-melting mixed glass powder and terpineol in proportion to prepare the piezoelectric ceramic low-temperature co-fired sintering agent.

In the invention, the piezoelectric ceramic low-temperature co-firing sintering agent is applied to piezoelectric ceramic integrated sintering.

Further, the sintering temperature of the low-temperature co-fired piezoelectric ceramic sintering agent during the integrated sintering of the piezoelectric ceramic is 700-750 ℃.

The glass transition temperature of the low-melting-point glass powder is 450-500 ℃, the glass softening temperature range is 490-560 ℃, the melting temperature range is 540-660 ℃, the melt flow range is 700-750 ℃, and the thermal expansion coefficient is 5.5-8.4 x 10 within the temperature range of 30-400 DEG C^-6The low-melting-point glass powder has the same or similar thermal expansion coefficient with the piezoelectric ceramic material, and can realize integrated sintering.

Advantageous effects

The low-temperature co-fired sintering agent for the piezoelectric ceramics has the same or similar thermal expansion coefficient with the piezoelectric ceramics, can be matched with the structure, mechanical property and electrical property of the piezoelectric ceramics, enables the connected piezoelectric ceramics to form an organic whole, improves the electrical property and the mechanical property of the piezoelectric ceramics bonded by organic glue, and simultaneously introduces the low-temperature co-fired ceramic technology into the sintering of the piezoelectric ceramics, can effectively reduce the sintering temperature of the piezoelectric ceramics, reduce the volatilization of PbO in lead-based piezoelectric ceramics, avoid the deviation of the stoichiometric ratio of ceramic components, and reduce the pollution to the environment on the basis of ensuring the original good property of the piezoelectric ceramics.

Detailed Description

In order to make the technical solutions of the present invention better understood, the following description is provided clearly and completely, and other similar embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present application based on the embodiments in the present application.

The parts described in the examples of the present invention are parts by weight.

Example 1

(1) The mixed glass powder with low melting point comprises the following components in percentage by weight: SiO 2₂ 45.0%，B₂O₃15.0%，Na₂O 6.0%，K₂O 1.0%，LiO₂ 3.0%，CaO1.0%，ZnO₂4.0%，ZrO₂ 4.0%，TiO₂ 2.0%；

(2) And (2) mixing 90 parts of the low-melting-point mixed glass powder in the step (1), 10 parts of PZT ceramic powder and 50 parts of terpineol to prepare the piezoelectric ceramic low-temperature co-fired sintering agent.

Example 2

(1) The mixed glass powder with low melting point comprises the following components in percentage by weight: SiO 2₂ 27.0%，Al₂O₃2.0%，B₂O₃ 30.0%，Na₂O 5.0%，K₂O 2.0%，LiO₂3.0%，CaO 3.0%，MgO 1.0%，ZnO19.0%，ZrO₂3.0%，Bi₂O₃ 5.0%；

(2) And (2) mixing 80 parts of the low-melting-point mixed glass powder in the step (1), 20 parts of PZT ceramic powder and 50 parts of terpineol to prepare the piezoelectric ceramic low-temperature co-fired sintering agent.

Example 3

(1) The mixed glass powder with low melting point comprises the following components in percentage by weight: SiO 2₂ 40.0%，Al₂O₃3.0%，B₂O₃ 18.0%，Na₂O 10.0%，LiO₂1.0%，ZnO 22.0%，ZrO₂4.0%，TiO₂2.0%；

(2) And (2) mixing 80 parts of the low-melting-point mixed glass powder in the step (1), 20 parts of PZT ceramic powder and 50 parts of terpineol to prepare the piezoelectric ceramic low-temperature co-fired sintering agent.

Example 4

(1) The mixed glass powder with low melting point comprises the following components in percentage by weight: SiO 2₂45.0%，B₂O₃15.0%，Na₂O 6.0%，K₂O 1.0%，LiO₂ 3.0%，CaO1.0%，ZnO₂4.0%，ZrO₂ 4.0%，TiO₂ 2.0%；

(2) And (2) mixing 70 parts of the low-melting-point mixed glass powder in the step (1), 30 parts of PZT ceramic powder and 50 parts of terpineol to prepare the piezoelectric ceramic low-temperature co-fired sintering agent.

Example 5

(1) The mixed glass powder with low melting point comprises the following components in percentage by weight: SiO 2₂ 27.0%，Al₂O₃2.0%， B₂O₃ 30.0%，Na₂O 5.0%，K₂O 2.0%，LiO₂3.0%，CaO 3.0%，MgO 1.0%， ZnO19.0%， ZrO₂3.0%，Bi₂O₃ 5.0%；

(2) And (2) mixing 60 parts of the low-melting-point mixed glass powder in the step (1), 40 parts of PZT ceramic powder and 50 parts of terpineol to prepare the piezoelectric ceramic low-temperature co-fired sintering agent.

Example 6

(1) The mixed glass powder with low melting point comprises the following components in percentage by weight: SiO 2₂ 40.0%，Al₂O₃3.0%， B₂O₃ 18.0%，Na₂O 10.0%，LiO₂1.0%，ZnO 22.0%，ZrO₂4.0%，TiO₂2.0%；

(2) And (2) mixing 50 parts of the low-melting-point mixed glass powder in the step (1), 50 parts of PZT ceramic powder and 50 parts of terpineol to prepare the piezoelectric ceramic low-temperature co-fired sintering agent.

Example 7

(1) The mixed glass powder with low melting point comprises the following components in percentage by weight: SiO 2₂ 27.0%，Al₂O₃2.0%， B₂O₃ 30.0%，Na₂O 5.0%，K₂O 2.0%，LiO₂3.0%，CaO 3.0%，MgO 1.0%， ZnO19.0%， ZrO₂3.0%，Bi₂O₃ 5.0%；

(2) And (2) mixing 90 parts of the low-melting-point mixed glass powder in the step (1), 10 parts of PZT ceramic powder and 50 parts of terpineol to prepare the piezoelectric ceramic low-temperature co-fired sintering agent.

Example 8

(1) The mixed glass powder with low melting point comprises the following components in percentage by weight: SiO 2₂ 40.0%，Al₂O₃3.0%， B₂O₃ 18.0%，Na₂O 10.0%，LiO₂ 1.0%，ZnO 22.0%，ZrO₂ 4.0%，TiO₂2.0%；

(2) And (2) mixing 80 parts of the low-melting-point mixed glass powder in the step (1), 20 parts of PZT ceramic powder and 50 parts of terpineol to prepare the piezoelectric ceramic low-temperature co-fired sintering agent.

Example 9

(1) Low melting pointThe mixed glass powder comprises the following components in percentage by weight: SiO 2₂ 45.0%，B₂O₃15.0%，Na₂O 6.0%，K₂O 1.0%，LiO₂ 3.0%，CaO 1.0%，ZnO₂ 4.0%，ZrO₂ 4.0%，TiO₂ 2.0%；

(2) And (2) mixing 70 parts of the low-melting-point mixed glass powder in the step (1), 30 parts of PZT ceramic powder and 50 parts of terpineol to prepare the piezoelectric ceramic low-temperature co-fired sintering agent.

Example 10

(1) The mixed glass powder with low melting point comprises the following components in percentage by weight: SiO 2₂ 40.0%，Al₂O₃3.0%， B₂O₃ 18.0%，Na₂O 10.0%，LiO₂1.0%，ZnO 22.0%，ZrO₂4.0%，TiO₂2.0%；

(2) And (2) mixing 60 parts of the low-melting-point mixed glass powder in the step (1), 40 parts of PZT ceramic powder and 50 parts of terpineol to prepare the piezoelectric ceramic low-temperature co-fired sintering agent.

Example 11

(1) The mixed glass powder with low melting point comprises the following components in percentage by weight: SiO 2₂45.0%，B₂O₃15.0%，Na₂O 6.0%，K₂O 1.0%，LiO₂ 3.0%，CaO1.0%，ZnO₂4.0%，ZrO₂ 4.0%，TiO₂ 2.0%；

(2) And (2) mixing 50 parts of the low-melting-point mixed glass powder in the step (1), 50 parts of PZT ceramic powder and 50 parts of terpineol to prepare the piezoelectric ceramic low-temperature co-fired sintering agent.

Performance testing

(1) And (3) comparing and analyzing the thermal expansion coefficient and the thermal phase transition temperature of the mixed glass powder:

the thermal expansion coefficients and the thermal phase transition temperatures of the three groups of low-melting-point mixed glass powders in the step (1) of the embodiments 1 to 3 are compared, and the results are shown in the following tables 1 and 2:

TABLE 1 thermal expansion coefficient (mum/DEG C) of three groups of low melting point mixed glass powders of examples 1-3 in different temperature ranges

TABLE 2 examples 1-3 three groups of low melting point glass frit blends with thermal transition temperature (. degree. C.)

As can be seen from table 1, the three melting point mixed glass powders in the embodiment of the present invention have the same or similar thermal expansion coefficients to the PZT piezoelectric ceramic material, and can achieve good matching with the PZT piezoelectric ceramic material; from table 2, it can be seen that the phase transition temperatures of the three melting point mixed glass powders in the embodiment of the present invention are set to 700 ℃ and 750 ℃ in order to ensure that the low temperature sintering agent can be completely melted and flows uniformly.

(2) And (3) testing electrical properties:

the piezoelectric ceramic samples with the shape of 4mm x 2mm sheets are prepared, the piezoelectric ceramic low-temperature co-fired sintering agents prepared in the examples 1-11 are used on one side for bonding, then sintering is carried out (wherein the sintering temperature of the piezoelectric ceramic low-temperature co-fired sintering agents in the examples 1-6 is 700 ℃, the sintering time is 2 hours, the sintering temperature of the piezoelectric ceramic low-temperature co-fired sintering agents in the examples 7-11 is 750 ℃, the sintering time is 2 hours), the sintered piezoelectric ceramic is subjected to high-voltage polarization treatment, the polarization temperature is 120 ℃, and the piezoelectric ceramic is polarized for 15 minutes according to the voltage of 3kV/mm, and the electrical and mechanical properties of the piezoelectric ceramic are tested. The piezoelectric strain constant and the relative dielectric constant were investigated by setting the epoxy resin composition as a comparison, and as a result, as shown in table 3 below, the electrical properties of the low-temperature sintering agent after sintering were excellent and much higher than those of the epoxy resin, as seen from table 3, among which the electrical properties of examples 3 and 7 were the best.

Table 3 comparison of electrical properties of the low-temperature co-fired sintering agent and the epoxy resin for the piezoelectric ceramics of examples 1 to 11

(3) Mechanical property detection

The piezoelectric ceramic low-temperature co-firing sintering agent prepared in the example 3 and the example 7 with the best electrical property is selected as an integrated sintering material, the PZT piezoelectric ceramic with a rod-shaped structure is selected as a substrate, sintering is respectively carried out at 700 ℃ and 750 ℃ to realize integration, a three-point bending resistance test is carried out after sintering is finished, and an original ceramic substrate which is not subjected to secondary sintering is set as a blank sample group (PZT ceramic) and an epoxy resin bonding group as a reference to carry out mechanical property test.

Three-point bending is a loading mode for measuring bending strength, namely, a sample is arranged between two lower sticks and an upper stick, the upper stick is positioned between the lower sticks, and the upper and lower sticks move relatively to cause the sample to bend. The principle is that the load is monitored through a displacement-time relation graph during the test, the bending load is applied to a long strip sample with a rectangular cross section until the sample is broken, and the bending strength of the sample is calculated through the critical load, the span and the sample size when the sample is broken.

The specific experimental method is as follows, according to the national standard (GB/T17671-1999), the ceramic-fracture resistance mechanical property test of stick-shaped bonding is carried out on the low-temperature sintering agent of the components, the beam speed of the experimental machine is 0.5mm/min, the sample size is 3mm 4mm 45mm, the chamfer angle is 45 degrees, each group of samples is not less than ten, and the average bending strength is calculated by mechanical comparison with the original ceramic matrix sample group and the epoxy resin bonding group which are not subjected to secondary sintering. The results of the average bending strength of each sample group are shown in table 4 below, and it can be seen from table 4 that the mechanical properties of PZT ceramics are the best, while example 3 has better electrical properties but poorer mechanical properties, and the low-temperature co-fired sintering agent for piezoelectric ceramics prepared in example 7 has not only good electrical properties but also excellent mechanical properties, which are obviously superior to the properties of epoxy resin.

TABLE 4 comparison of mechanical Properties of PZT ceramics, low-temperature co-fired ceramic sintering agent, and epoxy resin

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