CN114716238A

CN114716238A - Silicate series low-temperature sintering microwave dielectric ceramic material and preparation method thereof

Info

Publication number: CN114716238A
Application number: CN202210190447.4A
Authority: CN
Inventors: 童建喜; 谭金刚; 余祖高; 陆建军; 石珊
Original assignee: Jiaxing Glead Electronics Co ltd
Current assignee: Jiaxing Glead Electronics Co ltd
Priority date: 2022-02-28
Filing date: 2022-02-28
Publication date: 2022-07-08
Also published as: WO2023159896A1

Abstract

The invention relates to a silicate series low-temperature sintering microwave dielectric ceramic material and a preparation method thereof. The formula of the ceramic material comprises: ca_1‑x‑yMg_xZn_ySiO₃+awt％Ca_1‑zSr_zTiO₃+bwt％R₂O+cwt％Bi₂O₃+dwt％B₂O₃+ ewt% MO; wherein x is more than or equal to 0 and less than or equal to 0.5, y is more than or equal to 0 and less than or equal to 0.3, and z is more than or equal to 0 and less than or equal to 1; a is more than or equal to 0 and less than or equal to 18, b is more than or equal to 1 and less than or equal to 5,0<c≤3,0<d≤6,0≤e≤10；R₂O is Li₂O、K₂At least one of O; MO is ZnO, MgO, BaO, CuO, CoO, La₂O₃、SiO₂、MnO₂One or more of (a). The ceramic material and the silver electrode are co-fired well below 900 ℃, and can be applied to the fields of 5G communication, WiFi6 network communication and the likeThe field plate type LTCC filter, the radio frequency ceramic substrate, the multifunctional ceramic radio frequency module and the like.

Description

Silicate series low-temperature sintering microwave dielectric ceramic material and preparation method thereof

Technical Field

The invention belongs to the technical field of electronic materials, and particularly relates to a silicate low-temperature sintering microwave dielectric ceramic material and a preparation method thereof.

Background

In recent years, with rapid development of technologies such as a new generation mobile communication represented by 5G, WiFi6 network communication, millimeter wave communication, and the like, various electronic components, ceramic substrates, module products, and technologies have been advanced sufficiently. Chip electronic components, substrates and multifunctional radio frequency module products manufactured by Low Temperature Co-fired Ceramic technology (LTCC for short) have the characteristics of small size and thinness, high integration level, good high-frequency performance and reliability and the like, and are widely applied to the fields of mobile base stations, smart phones, portable wearable devices, wireless routers, military radio frequency communication devices, radars, navigation terminals and the like.

The LTCC technology needs microwave dielectric ceramics and high-conductivity low-melting-point metals Ag and Cu as internal electrodes, and generally requires sintering densification temperature below 900 ℃. Most microwave dielectric ceramic materials have excellent microwave dielectric properties, but the sintering temperature is very high (generally 1200-1500 ℃), and in order to realize co-sintering with electrodes such as Ag, Cu and the like, a large amount of glass aids or low-melting-point oxides are usually required to be added to reduce the sintering temperature of the microwave dielectric ceramic materials. A great number of papers and patents on low-temperature sintering microwave dielectric ceramics are published. In application-oriented application, the low-temperature sintered microwave dielectric ceramic material needs to meet a plurality of performance requirements, can be sintered compactly below 900 ℃, has a proper dielectric constant, low dielectric loss and a frequency temperature coefficient, and also has good co-firing matching with metal electrodes such as Ag (for example, obvious Ag diffusion does not occur, good interface bonding of the ceramic and the Ag electrode, sintering shrinkage matching ensures that the product is sintered flatly, and the like). In addition, the LTCC ceramics need a suitable thermal expansion coefficient matching that of the chip or the circuit board to be mounted. In addition, the steel plate should have sufficient mechanical strength, environmental reliability and other performances, and have corrosion resistance to electroplating or chemical plating solution, and the steel plate should meet the requirements of environmental protection regulations in the civil field. Therefore, the low-temperature sintered microwave dielectric ceramic material with good comprehensive performance which can be practically applied is less.

(Ca,Mg)SiO₃The microwave dielectric ceramic has good dielectric property and low material cost. In patent application CN112759378A, a CaO-MgO-TiO compound is described₂-SiO₂The ceramic material is modified and sintered by introducing manganese oxide, and lithium oxide and bismuth oxide are added into the mixture as sintering aid in a compounding way and are mixed with TiO₂Materials combined to form eutectic points Li₂TiO₃(900 ℃) and reducing the sintering temperature to be below 900 ℃. The patent application also discloses a method for the preparation of the material: all the raw materials are mixed at one time, and are synthesized by spray drying and calcining, and then the ceramic material powder is prepared by a spray granulation method. The patent application does not disclose the phase composition of the ceramic material, and the adoption of the one-step mixing and synthesizing process of the base material and the auxiliary agent can cause uncontrollable reaction among components during pre-sintering, and the generated phase is complex and uncertain. Therefore, the quality factor frequency product Qf of the prepared ceramic is relatively low (10000-12000 GHz).

Patent CN 200410039848.1 reports on (Ca, Mg) SiO₃The system is a main component and adopts CaTiO₃Adjustment of temperature coefficient of frequency, Li₂CO₃And V₂O₅The formula and the preparation process of the low-temperature sintering microwave dielectric ceramic material serving as a sintering aid can realize good co-firing matching with a silver electrode, and the material properties are as follows: dielectric constant 8-10, Qf>25000GHz, the material has achieved batch application. However, this material has the following problems: (1) low melting point oxide V₂O₅Has excellent combustion-supporting effect, and can obviously reduce (Ca, Mg) SiO₃The sintering temperature of the ceramic is high, but the ceramic has high toxicity and is harmful to human bodies, and the environment-friendly requirement which is increasingly emphasized cannot be met. (2) V₂O₅The liquid phase formed in the sintering process promotes the sintering of the ceramic, and simultaneously, the short-distance diffusion of the silver electrode is easily promoted, particularly, in a circuit with the thickness of a single-layer LTCC dielectric layer being less than 30um, the interlayer circuit short circuit risk caused by silver migration is easily caused, and the serious hidden trouble of poor product reliability is caused.

Disclosure of Invention

In view of the above problems and needs in the prior art, an object of the present invention is to provide a silicate-based low-temperature sintered microwave dielectric ceramic material, which has the characteristics of environmental protection, high reliability, low cost and good comprehensive performance, and can meet the requirements of the products such as chip LTCC filters, radio frequency ceramic substrates, multifunctional ceramic radio frequency modules, etc. in the fields of 5G communication, WiFi6 network communication, millimeter wave communication, etc. on the LTCC ceramic material. The invention also aims to provide a preparation method of the low-temperature sintering microwave dielectric ceramic material.

In order to achieve the above object of the first invention, the invention adopts the following technical solutions:

a silicate series low-temperature sintering microwave dielectric ceramic material has a formula expression as follows: ca_1-x- _yMg_xZn_ySiO₃+awt％Ca_1-zSr_zTiO₃+bwt％R₂O+cwt％Bi₂O₃+dwt％B₂O₃+ ewt% MO; wherein:

0≤x≤0.5,0≤y≤0.3,0≤z≤1；

0≤a≤18,1≤b≤5,0<c≤3,0<d is less than or equal to 6, e is more than or equal to 0 and less than or equal to 10; a. b, c, d and e are respectively Ca_1-zSr_zTiO₃、R₂O、Bi₂O₃、B₂O₃And MO phase in Ca_1-x-yMg_xZn_ySiO₃Mass fraction of (a);

R₂o is Li₂O、K₂At least one of O;

MO is ZnO, MgO, BaO, CuO, CoO, La₂O₃、SiO₂、MnO₂One or more of (a).

Further, R₂O、B₂O₃And MO is replaced by its corresponding metal ion valence transition oxide, carbonate or hydroxide in terms of equimolar amounts of metal ion.

In order to achieve the above object of the second invention, the invention adopts the following technical scheme:

a method for preparing a silicate series low-temperature sintering microwave dielectric ceramic material comprises the following steps:

(1) according to Ca_1-x-yMg_xZn_ySiO₃Wherein x is more than or equal to 0 and less than or equal to 0.5, and y is more than or equal to 0 and less than or equal to 0.3, and CaCO is weighed as a main material in a stoichiometric ratio₃MgO, ZnO and SiO₂According to the mass ratio of 1: 1-2, adding deionized water, mixing materials by a wet method for 16-24h, drying at 120 ℃, sieving the dried mixture by a 40-mesh sieve, loading into an alumina crucible, calcining at the temperature of 1100-1260 ℃ for 2-4h to synthesize a main crystal phase, and grinding the main crystal phase to be used as a ceramic base material for later use;

(2) according to Ca_1-zSr_zTiO₃Wherein z is more than or equal to 0 and less than or equal to 1, and weighing main material CaCO in stoichiometric proportion₃、SrCO₃And TiO₂According to the mass ratio of 1: 1-2, adding deionized water, mixing materials by a wet method for 16-24h, drying at 120 ℃, sieving the dried mixture by a 40-mesh sieve, loading into an alumina crucible, calcining at 950-1100 ℃ for 2-4h, synthesizing a main crystal phase, and grinding the main crystal phase to serve as a ceramic base material for later use;

(3) in terms of bwt% R₂O+cwt％Bi₂O₃+dwt％B₂O₃+ ewt% MO, weighing Li₂CO₃、K₂CO₃、Bi₂O₃、B₂O₃Or H₃BO₃ZnO, MgO or Mg (OH)₂、BaCO₃CuO, CoO or Co₂O₃、La₂O₃、SiO₂、MnO₂Or MnCO₃And (2) raw materials are mixed according to the mass ratio of 1: 1-2, adding absolute ethyl alcohol, mixing materials by a wet method for 16-24h, drying at 80 ℃, sieving the dried mixture by a 40-mesh sieve, loading into an alumina crucible, calcining at 500-700 ℃ for 2-4h, grinding and using as a sintering aid for later use, wherein b is more than or equal to 1 and less than or equal to 5, and b is 0<c≤3,0<d is less than or equal to 6, e is less than or equal to 10 and is more than or equal to 0, and b, c, d and e are respectively R₂O、Bi₂O₃、B₂O₃And MO phase in Ca_1-x-yMg_xZn_ySiO₃Mass fraction of (a);

(4) will make intoPrepared Ca_1-x-yMg_xZn_ySiO₃、Ca_1-zSr_zTiO₃Ceramic base and sintering aid according to Ca_1-x- _yMg_xZn_ySiO₃+awt％Ca_1-zSr_zTiO₃+bwt％R₂O+cwt％Bi₂O₃+dwt％B₂O₃And (3) mixing the materials according to the mass ratio of + ewt% MO to absolute ethyl alcohol of 1: 1-2, adding absolute ethyl alcohol, mixing for 4-8h by adopting a wet method, then transferring the ceramic slurry into a sand mill for sand milling, wherein ZrO with the diameter phi of 0.1-0.8mm is adopted in the sand milling process₂Grinding balls, controlling the rotating speed of a main rotating shaft of a sand mill to be 1000-2000 rpm, grinding for 4-12h, controlling the particle size D50 of the powder to be 0.5-1.2 um and the particle size D90 to be 1.0-2.0 um, transferring ceramic slurry out, and drying at 80 ℃ to obtain the low-temperature sintering microwave dielectric ceramic material.

The invention adopts the formula and the process, and the obtained ceramic material can be co-fired with the silver electrode at the temperature of below 900 ℃ and has excellent microwave dielectric property: dielectric constant Epsilon r is 7-12, quality factor frequency product Qf reaches 20000GHz, and frequency temperature coefficient tau_fIs adjustable. The preparation process is simple, the reproducibility is good, the cost is low, the comprehensive performance is good, and the silver electrode can be co-fired well. The requirements of products such as chip type LTCC filters, radio frequency ceramic substrates and multifunctional ceramic radio frequency modules in the fields of 5G communication, WiFi6 network communication, millimeter wave communication and the like on LTCC ceramic materials can be met. Compared with the prior art, the invention has the following characteristics:

(1) by the reaction of CaSiO₃The Ca position of the ceramic is substituted by ions, the sintering temperature of the material is widened, the Q value of the material is improved, and the Ca of the second phase is introduced_1-zSr_zTiO₃Regulating the frequency temperature coefficient TCF of the material, and introducing the alkali metal oxide Li₂O、K₂O and Bi₂O₃、B₂O₃The environment-friendly and nontoxic composite oxide sintering aid forms Li with eutectic point (lower than 700 ℃), and the like₂O(K₂O)-Bi₂O₃-B₂O₃And reducing the sintering temperature of the ceramic to below 900 ℃. Pottery clayThe phase of the porcelain is easier to control, the cooling effect of the eutectic compound is better, and the obtained ceramic material has better dielectric property.

(2) Alkali metal oxide and Bi introduced in low-temperature sintering microwave dielectric ceramic₂O₃、V₂O₅The low-melting active oxides have good cooling sintering effect, but are easy to become diffusion channels of metal atoms or ions such as Ag and the like. The invention carries out synergistic cooling by introducing other composite oxides and controls the alkali metal oxide and Bi₂O₃The additive amount of the silver-based composite material obviously avoids the interlayer circuit short circuit risk caused by silver migration which is very easy to occur when the ceramic material and the silver electrode are co-fired.

(3) In the preparation method of the low-temperature sintering microwave dielectric ceramic material, the problem of B during preparation of ceramic tape-casting slurry is solved by pre-mixing and calcining various sintering aid oxides and adopting absolute ethyl alcohol as a ball-milling solvent in the final mixing and sand-milling process₂O₃The cross-linking reaction between the free hydroxyl in the oxide and powder and the hydroxyl in the adhesive such as PVB causes the problem that the slurry has large viscosity and cannot obtain high-quality green ceramic chips.

(4) The ceramic material with finer and more concentrated granularity is obtained by a sand grinding process, so that the preparation of the green ceramic chip with the thickness of less than 30um is facilitated, the microscopic defects of the green ceramic chip are reduced, the risks of interlayer short circuit, electric breakdown and the like of an application device are reduced, and the reliability of the product is improved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.

FIG. 1 is a scanning electron microstructure and EDS linear Ag element analysis of a co-fired interface of a ceramic material and a silver electrode according to the present invention.

Detailed Description

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, and the embodiments described below with reference to the accompanying drawings are exemplary and intended to be illustrative of the present invention and should not be construed as limiting the present invention.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Examples 1 to 6

The formulations of the silicate-based low-temperature sintered microwave dielectric ceramic materials of examples 1 to 6 are shown in Table 1. The preparation method comprises the following steps:

(1) according to Ca_1-x-yMg_xZn_ySiO₃(the specific formula is shown in table 1) weighing CaCO as a main material in stoichiometric proportion₃MgO, ZnO and SiO₂According to the mass ratio of 1: 1.8 adding deionized water, mixing materials by a wet method for 18h, drying at 120 ℃, sieving the dried mixture by a 40-mesh sieve, filling into an alumina crucible, calcining at 1200 ℃ for 4h to synthesize a main crystal phase, and grinding the main crystal phase to be used as a ceramic base material for later use.

(2) According to Ca_1-zSr_zTiO₃(the specific formula is shown in table 1) weighing CaCO as a main material in stoichiometric proportion₃、SrCO₃And TiO₂According to the mass ratio of 1: 1.5 adding deionized water, mixing materials by a wet method for 24 hours, drying at 120 ℃, sieving the dried mixture by a 40-mesh sieve, putting the mixture into an alumina crucible, calcining at 1050 ℃ for 3 hours to synthesize a main crystal phase, and grinding the main crystal phase to be used as a ceramic base material for later use.

(3) In terms of bwt% R₂O+cwt％Bi₂O₃+dwt％B₂O₃+ ewt% MO (specific formula shown in Table 2), and weighing Li₂CO₃、K₂CO₃、Bi₂O₃、B₂O₃Or H₃BO₃、ZnO、MgO、BaCO₃CuO, CoO or Co₂O₃、La₂O₃、SiO₂、MnO₂Or MnCO₃And (3) raw materials are mixed according to the mass ratio of the mixture to the absolute ethyl alcohol of 1: 1.5 adding ethanol, mixing materials by a wet method for 18 hours, drying at 80 ℃,and (3) sieving the dried mixture by a 40-mesh sieve, loading the mixture into an alumina crucible, calcining the mixture for 3 hours at 600 ℃, and grinding the mixture to be used as a sintering aid for later use.

(4) The prepared Ca_1-x-yMg_xZn_ySiO₃、Ca_1-zSr_zTiO₃The ceramic base material and the sintering aid are mixed according to the mass ratio in table 1, and the mass ratio of the ceramic base material to the absolute ethyl alcohol is 1: 1.5 adding absolute ethyl alcohol, and mixing materials for 5 hours by adopting a wet method. The ceramic slurry is then transferred to a sand mill for sanding. ZrO with the diameter of phi 0.6mm is adopted in the sanding process₂Grinding balls, controlling the rotating speed of a main rotating shaft of a sand mill to be 1200rpm, grinding for 4-8h, controlling the powder granularity D50 to be 0.8-1.0 um and the D90 to be 1.2-1.8 um, then transferring ceramic slurry out, and drying at 80 ℃ to obtain the low-temperature sintering microwave dielectric ceramic material.

TABLE 1

TABLE 2

Adding 8 wt% of polyvinyl alcohol (PVA) adhesive into a ceramic material for granulation, pressing into round blocks with the diameter of 20mm and the thickness of 8-9 mm under the pressure of 100MPa, sintering for 3 hours at the temperature of 900 ℃ in atmospheric atmosphere, and measuring the volume density of the round block samples after sintering by an Archimedes method. After the surface of the sample is polished, the microwave dielectric property of the sample is measured by adopting an Agilent 8719ET (50 MHz-13.5 GHz) network analyzer. Temperature coefficient of frequency τ of sample_fMeasured at a temperature of 25-110 ℃ and expressed by the formula tau_f＝(f₁₁₀-f₂₅)/(f₂₅X 85) where f₁₁₀And f₂₅The resonant center frequencies are at 110 c and 25 c, respectively.

The results of the performance testing of the materials of examples 1-6 are set forth in Table 3.

TABLE 3

Numbering	ε_r	Q×f(GHz)	τ_f(ppm/℃)
				Example 1	7.1	21600	-35
Example 2	7.9	20450	-21
				Example 3	9.2	19360	-3.6
Example 4	9.9	17420	0.5
				Example 5	10.5	16200	10.3
Example 6	11.2	14500	23.0

Examples 7 to 12

The formulations of the silicate based low temperature sintered microwave dielectric ceramic materials of examples 7-12 are shown in Table 3. The preparation method comprises the following steps:

(1) according to Ca_1-x-yMg_xZn_ySiO₃(the specific formula is shown in Table 4) weighing CaCO as the main material in stoichiometric proportion₃MgO, ZnO and SiO₂According to the mass ratio of 1: 1.5 adding deionized water, mixing materials by a wet method for 18h, drying at 120 ℃, sieving the dried mixture by a 40-mesh sieve, filling into an alumina crucible, calcining at 1100 ℃ for 3h to synthesize a main crystal phase, and grinding the main crystal phase to be used as a ceramic base material for later use.

(2) According to Ca_1-zSr_zTiO₃(the specific formula is shown in Table 4) weighing CaCO as the main material in stoichiometric proportion₃、SrCO₃And TiO₂According to the mass ratio of 1: 1.5 adding deionized water, mixing materials by a wet method for 24 hours, drying at 120 ℃, sieving the dried mixture by a 40-mesh sieve, filling into an alumina crucible, calcining at 1000 ℃ for 3 hours, synthesizing a main crystal phase, and grinding the main crystal phase to be used as a ceramic base material for later use.

(3) In terms of bwt% R₂O+cwt％Bi₂O₃+dwt％B₂O₃+ ewt% MO (specific formulation is shown in Table 5), and Li is weighed₂CO₃、K₂CO₃、Bi₂O₃、B₂O₃Or H₃BO₃、ZnO、MgO、BaCO₃CuO, CoO or Co₂O₃、La₂O₃、SiO₂、MnO₂Or MnCO₃And (3) raw materials are mixed according to the mass ratio of the mixture to the absolute ethyl alcohol of 1: 1.5 adding ethanol, mixing materials by a wet method for 16h, drying at 80 ℃, sieving the dried mixture by a 40-mesh sieve, loading into an alumina crucible, calcining at 650 ℃ for 3h, grinding, and sinteringAnd (4) preparing the auxiliary agent for later use.

(4) The prepared Ca_1-x-yMg_xZn_ySiO₃、Ca_1-zSr_zTiO₃The ceramic base material and the sintering aid are mixed according to the mass ratio in table 3, and the mass ratio of the ceramic base material to the absolute ethyl alcohol is 1: 1.5 adding absolute ethyl alcohol, and mixing materials for 5 hours by adopting a wet method. The ceramic slurry is then transferred to a sand mill for sanding. ZrO with diameter phi of 0.6mm is adopted in the sanding process₂Grinding balls, controlling the rotating speed of a main rotating shaft of a sand mill to be 1200rpm, grinding for 4-8h, controlling the powder granularity D50 to be 0.9-1.1 um and the D90 to be 1.5-1.9 um, then transferring ceramic slurry out, and drying at 80 ℃ to obtain the low-temperature sintering microwave dielectric ceramic material.

TABLE 4

TABLE 5

Adding 5 wt% of polyvinyl alcohol (PVA) adhesive into a ceramic material for granulation, pressing into round blocks with the diameter of 20mm and the thickness of 8-9 mm under the pressure of 100MPa, sintering for 2 hours at 880 ℃ in atmospheric atmosphere, and measuring the volume density of the round block samples after sintering by an Archimedes method. After the surface of the sample is polished, the microwave dielectric property of the sample is measured by adopting an Agilent 8719ET (50 MHz-13.5 GHz) network analyzer. Temperature coefficient of frequency τ of sample_fMeasured at a temperature of 25-110 ℃ and expressed by the formula tau_f＝(f₁₁₀-f₂₅)/(f₂₅X 85) where f₁₁₀And f₂₅The resonant center frequencies are at 110 c and 25 c, respectively.

The results of the performance testing of the materials of examples 7-12 are set forth in Table 6.

TABLE 6

Numbering	ε_r	Q×f(GHz)	τ_f(ppm/℃)
				Example 7	7.7	20380	-18
Example 8	9.6	17850	-9
				Example 9	10.2	13620	3
Example 10	10.3	18980	-2
				Example 11	10.3	19440	4
Example 12	9.7	20790	-5

Examples 13 to 18

The formulations of the silicate-based low-temperature sintered microwave dielectric ceramic materials of examples 13 to 18 are shown in Table 7. The preparation method comprises the following steps:

(1) according to Ca_1-x-yMg_xZn_ySiO₃(the specific formula is shown in Table 7) weighing CaCO as the main material in stoichiometric proportion₃MgO, ZnO and SiO₂According to the mass ratio of 1: 1.5 adding deionized water, mixing materials by a wet method for 18h, drying at 120 ℃, sieving the dried mixture by a 40-mesh sieve, filling into an alumina crucible, calcining at 1050 ℃ for 3h to synthesize a main crystal phase, and grinding the main crystal phase to be used as a ceramic base material for later use.

(2) According to Ca_1-zSr_zTiO₃(the specific formula is shown in Table 7) weighing CaCO as the main material in stoichiometric proportion₃、SrCO₃And TiO₂According to the mass ratio of 1: 1.5 adding deionized water, mixing materials by a wet method for 24 hours, drying at 120 ℃, sieving the dried mixture by a 40-mesh sieve, putting the mixture into an alumina crucible, calcining at 1000 ℃ for 3 hours to synthesize a main crystal phase, and grinding the main crystal phase to be used as a ceramic base material for later use.

(3) The prepared Ca_1-x-yMg_xZn_ySiO₃、Ca_1-zSr_zTiO₃The ceramic base materials and the sintering aids S4 and S11 prepared in examples 1 to 12 were compounded in the mass ratio in table 7, where the mass ratio of the materials to the absolute ethyl alcohol is 1: 1.5 adding absolute ethyl alcohol, and mixing materials for 5 hours by adopting a wet method. The ceramic slurry is then transferred to a sand mill for sanding. ZrO with the diameter of phi 0.6mm is adopted in the sanding process₂Grinding balls, controlling the rotating speed of a main rotating shaft of a sand mill to be 1500rpm, grinding for 6-8h, controlling the powder granularity D50 to be 0.5-0.8 um and the D90 to be 1.0-1.5 um, then transferring ceramic slurry out, and drying at 80 ℃ to obtain the low-temperature sintering microwave dielectric ceramic material.

TABLE 7

Adding 8 wt% of polyvinyl alcohol (PVA) adhesive into a ceramic material for granulation, pressing into round blocks with the diameter of 20mm and the thickness of 8-9 mm under the pressure of 100MPa, sintering for 2 hours in an atmosphere at 880 ℃, and measuring the volume density of the round block samples after sintering by an Archimedes method. And after the surface of the sample is polished, measuring the microwave dielectric property of the sample by adopting an Agilent 8719ET (50 MHz-13.5 GHz) network analyzer. Temperature coefficient of frequency τ of sample_fMeasured at a temperature of 25-110 ℃ and expressed by the formula tau_f＝(f₁₁₀-f₂₅)/(f₂₅X 85) where f₁₁₀And f₂₅The resonant center frequencies are at 110 c and 25 c, respectively.

The results of the performance testing of the materials of examples 13-18 are set forth in Table 8.

TABLE 8

Numbering	ε_r	Q×f(GHz)	τ_f(ppm/℃)
				Example 13	9.8	19260	-8
Example 14	10.0	20080	-2
				Example 15	10.5	17530	3
Example 16	9.7	14440	-9
				Example 17	9.0	13880	-12
Example 18	8.4	14350	-15

The ceramic material in example 14 is subjected to tape casting to prepare a thin LTCC green tape (with a green ceramic thickness of 30um), and LTCC device samples are prepared through LTCC device preparation processes such as punching, hole filling, screen printing, laminating, isostatic pressing, cutting, sintering and the like, wherein the cross section of the LTCC device is subjected to backscatter SEM and energy spectrum linear Ag element scanning analysis, and the results are shown in fig. 1. The ceramic material is tightly combined with a silver electrode co-firing interface at 880 ℃, and the diffusion condition of silver element is not obvious. The ceramic material can be applied to various miniaturized LTCC devices.

The foregoing is a more detailed description of the invention, taken in conjunction with specific preferred embodiments thereof, and is not intended to limit the invention to the particular forms disclosed. Based on the results of a number of experiments conducted by the applicant, it was confirmed that the object of the present invention can be achieved within the scope of the claims of the present invention.

It is also noted that, in the description of the present invention, the terms "comprises," "comprising," and the like, are intended to cover a non-exclusive inclusion, as well as processes, methods, materials, and the like, which do not include other elements not expressly listed. "embodiment" or a "specific embodiment" and the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention.

Therefore, although the present invention has been described by using the specific embodiments, it should be understood that the above embodiments are for understanding the method and the core matters of the present invention, and should not be construed as limiting the present invention. Variations, modifications, substitutions and variations of the above-described embodiments may be made by those skilled in the art without departing from the principle and spirit of the invention, and any simple modification, equivalent change and modification of the above embodiments in accordance with the technical spirit of the invention should be considered as the protection scope of the present invention.

Claims

1. The silicate series low-temperature sintering microwave dielectric ceramic material is characterized in that the formula expression of the material is as follows: ca_1-x-yMg_xZn_ySiO₃+awt％Ca_1-zSr_zTiO₃+bwt％R₂O+cwt％Bi₂O₃+dwt％B₂O₃+ ewt% MO; wherein:

0≤x≤0.5,0≤y≤0.3,0≤z≤1；

0≤a≤18,1≤b≤5,0<c≤3,0<d is less than or equal to 6, e is more than or equal to 0 and less than or equal to 10; a. b, c, d and e are respectively Ca_1-zSr_zTiO₃、R₂O、Bi₂O₃、B₂O₃And MO phase in Ca_1-x-yMg_xZn_ySiO₃The mass fraction of (a);

R₂o is Li₂O、K₂At least one of O;

MO is ZnO, MgO, BaO, CuO, CoO, La₂O₃、SiO₂、MnO₂One or more of (a).

2. The low dielectric wollastonite low temperature co-fired ceramic material as claimed in claim 1, wherein R is₂O、B₂O₃And MO is replaced by its corresponding metal ion valence transition oxide, carbonate or hydroxide in terms of equimolar amounts of metal ion.

3. The method for preparing the silicate system low-temperature sintering microwave dielectric ceramic material according to the claim 1 or 2, characterized by comprising the following steps:

(2) according to Ca_1-zSr_zTiO₃Wherein z is more than or equal to 0 and less than or equal to 1, and weighing CaCO as a main material in a stoichiometric ratio₃、SrCO₃And TiO₂According to the mass ratio of 1: 1-2, adding deionized water, mixing materials by a wet method for 16-24h, drying at 120 ℃, sieving the dried mixture by a 40-mesh sieve, loading into an alumina crucible, calcining at 950-1100 ℃ for 2-4h, synthesizing a main crystal phase, and grinding the main crystal phase to serve as a ceramic base material for later use;

(3) in terms of bwt% R₂O+cwt％Bi₂O₃+dwt％B₂O₃+ ewt% MO, weighing Li₂CO₃、K₂CO₃、Bi₂O₃、B₂O₃Or H₃BO₃ZnO, MgO or Mg (OH)₂、BaCO₃CuO, CoO or Co₂O₃、La₂O₃、SiO₂、MnO₂Or MnCO₃And (2) raw materials are mixed according to the mass ratio of 1: 1-2, adding absolute ethyl alcohol, and mixing by adopting a wet methodDrying the material at 80 ℃ after 16-24h, sieving the dried mixture with a 40-mesh sieve, loading the mixture into an alumina crucible, calcining the mixture at 500-700 ℃ for 2-4h, grinding the mixture to be used as a sintering aid for later use, wherein b is more than or equal to 1 and less than or equal to 5, and 0<c≤3,0<d is less than or equal to 6, e is less than or equal to 10 and is more than or equal to 0, and b, c, d and e are respectively R₂O、Bi₂O₃、B₂O₃And MO phase in Ca_1-x-yMg_xZn_ySiO₃Mass fraction of (a);

(4) the prepared Ca_1-x-yMg_xZn_ySiO₃、Ca_1-zSr_zTiO₃Ceramic base and sintering aid according to Ca_1-x- _yMg_xZn_ySiO₃+awt％Ca_1-zSr_zTiO₃+bwt％R₂O+cwt％Bi₂O₃+dwt％B₂O₃And (3) mixing the materials according to the mass ratio of + ewt% MO to absolute ethyl alcohol of 1: 1-2, adding absolute ethyl alcohol, mixing for 4-8h by adopting a wet method, then transferring the ceramic slurry into a sand mill for sand milling, wherein ZrO with the diameter phi of 0.1-0.8mm is adopted in the sand milling process₂Grinding balls, controlling the rotating speed of a main rotating shaft of a sand mill to be 1000-2000 rpm, grinding for 4-12h, controlling the particle size D50 of the powder to be 0.5-1.2 um and the particle size D90 to be 1.0-2.0 um, transferring ceramic slurry out, and drying at 80 ℃ to obtain the low-temperature sintering microwave dielectric ceramic material.