阅读说明：本技术 一种用于单腔滤波器的低介电常数介质材料及其制备方法 (Low dielectric constant dielectric material for single-cavity filter and preparation method thereof ) 是由 谢义鹏 薛伟志 林小冬 符仁敏 于 2021-09-26 设计创作，主要内容包括：本发明公开了一种用于单腔滤波器的低介电常数介质材料及其制备方法,单腔滤波器的低介电常数介质材料的结构为(1-z/2)Mg-(2)SiO-(4)-(z/2)M-(2)SiO-(4)-mCa-((x/2))Ln-((2/3-x/3))TiO-(3)-ySnO-(2)-(0.05～0.15)wt%AF。单腔滤波器的低介电常数介质材料的制备方法,包括Ca-((x/2))Ln-((2/3-x/3))TiO-(3)晶相的预制备,配料,一次研磨,喷雾干燥,烧块,二次研磨和喷雾造粒。本发明根据上述内容提出一种用于单腔滤波器的低介电常数介质材料及其制备方法,目的之一是提供一种品质因数高和抗折强度高的低介电常数介质材料；目的之二是提供一种制备简单,原料易得,能够规模化生产和成本交底的制备方法。(The invention discloses a low dielectric constant dielectric material for a single-cavity filter and a preparation method thereof, wherein the low dielectric constant dielectric material of the single-cavity filter has a structure of (1-z/2) Mg 2 SiO 4 ‑(z/2)M 2 SiO 4 ‑mCa （x/2） Ln (2/3‑x/3) TiO 3 ‑ySnO 2 - (0.05 to 0.15) wt% AF. A process for preparing low-dielectric-constant dielectric material of single-cavity filter includes Ca （x/2） Ln (2/3‑x/3) TiO 3 Preparing crystal phase, proportioning, grinding, spray dryingBurning, secondary grinding and spray granulation. The invention provides a low dielectric constant dielectric material for a single-cavity filter and a preparation method thereof, and aims to provide a low dielectric constant dielectric material with high quality factor and high flexural strength; the other purpose is to provide a preparation method which is simple in preparation, easy in raw material obtaining, and capable of realizing large-scale production and cost reduction.)

1. A low dielectric constant dielectric material for a single cavity filter, comprising: the low dielectric constant dielectric material has the structure of (1-z/2) Mg₂SiO₄-(z/2)M₂SiO₄-mCa_（x/2）Ln_(2/3-x/3)TiO₃-ySnO₂-(0.05～0.15)wt%AF；

The QF value is larger than 52000GHz, the relative dielectric constant Epsilon is 7.5, the value of the temperature coefficient of the resonance frequency within-40-125 ℃ is smaller than 4 ppm/DEG C, and the flexural strength is larger than 320 MPa;

the range of x is 0.2 to 0.4, the range of y is 0.01 to 0.04, the range of z is 0.05 to 0.18, and the range of m is 0.03 to 0.12.

2. A preparation method of a low dielectric constant dielectric material for a single-cavity filter is characterized by comprising the following steps: a low dielectric constant dielectric material for a single cavity filter as claimed in claim 1, comprising the steps of:

step 1: ca_（x/2）Ln_(2/3-x/3)TiO₃Preparation of the crystalline phase:

accurately weighing 1 part of titanium dioxide, (x/2) part of calcium carbonate, (2/6-x/6) part of lanthanide oxide and 40 parts of deionized water according to molar parts, adding the weighed materials into a ball mill, grinding the materials until D50=0.5 +/-0.1 mu m and D90=1.0 +/-0.2 mu m to obtain a ball grinding material, carrying out spray drying on the ball grinding material, then carrying out heat preservation for 6 +/-2 h at 1120 +/-30 ℃, and naturally cooling to obtain Ca_（x/2）Ln_(2/3-x/3)TiO₃A crystalline phase;

step 2: ingredients

Accurately weighing (2-z) parts of magnesium hydroxide according to molar parts1 part of anhydrous silicic acid, z parts of transition metal hydroxide, y parts of stannic oxide and m parts of Ca_（x/2）Ln_(2/3-x/3)TiO₃Crystallizing to obtain a mixture of ingredients;

and step 3: one-time grinding

Uniformly dispersing the ingredient mixture, deionized water which is 2 times of the weight of the ingredient mixture and a dispersing agent which is 0.5% of the weight of the ingredient mixture at a high speed by adopting a sand grinding mode, and then grinding until D50=0.2 +/-0.1 mu m and D90=0.4 +/-0.2 mu m to obtain primary slurry;

and 4, step 4: spray drying

Spray drying the primary slurry material by adopting a pressure type spray drying tower to obtain a dried material;

and 5: baked block

Keeping the temperature of the dried material at the actual temperature of 1080 +/-30 ℃ for 6 +/-2 hours, and naturally cooling to obtain a sintered material;

step 6: secondary grinding

Crushing the baked materials, sieving the crushed baked materials with a 40-mesh sieve, accurately weighing the baked materials which pass through the 40-mesh sieve, meanwhile weighing 0.05 to 0.15 percent of fluoride, weighing 80 percent of deionized water and 0.5 percent of dispersant, stirring and uniformly dispersing the baked materials, the deionized water and the dispersant which pass through the 40-mesh sieve, and then sanding the mixture until D50=0.8 +/-0.1 mu m and D90=1.5 +/-0.25 mu m to obtain secondary slurry;

and 7: spray granulation

Adding a PVA solution with the weight fraction of 16% into the secondary slurry, wherein the adding amount is 12% + -4% of the weight of the clinker which passes through the 40-mesh sieve in the step 6, and simultaneously adding a release agent with the weight of 0.5% of the weight of the clinker which passes through the 40-mesh sieve in the step 6; and after uniformly stirring, carrying out spray granulation on the slurry, and sieving the slurry by a sieve of 60 meshes to remove coarse powder and a sieve of 250 meshes to remove fine powder to obtain a granulation material of 60 meshes to 250 meshes, namely the low dielectric constant dielectric material.

3. The method of claim 2, wherein the dielectric material has a low dielectric constant, and is used for a single-cavity filter, the method comprising: the transition metal hydroxide is transition metal cation Zn²⁺、Mn²⁺、Co²⁺、Ni²⁺、Cu²⁺At least one of the hydroxides of (1).

4. The method of claim 2, wherein the dielectric material has a low dielectric constant, and is used for a single-cavity filter, the method comprising: the lanthanide oxide is at least one of lanthanum oxide, samarium oxide, neodymium oxide and praseodymium oxide.

5. The method of claim 2, wherein the dielectric material has a low dielectric constant, and is used for a single-cavity filter, the method comprising: the transition metal hydroxide, lanthanide oxide, magnesium hydroxide and calcium carbonate all have particle sizes <0.5 microns and purities > 99.5%.

6. The method of claim 2, wherein the dielectric material has a low dielectric constant, and is used for a single-cavity filter, the method comprising: the fluoride is at least one of magnesium fluoride, lithium fluoride, zinc fluoride or calcium fluoride.

7. The method of claim 2, wherein the dielectric material has a low dielectric constant, and is used for a single-cavity filter, the method comprising: the dispersant is polycarboxylate dispersant.

8. The method of claim 2, wherein the dielectric material has a low dielectric constant, and is used for a single-cavity filter, the method comprising: the release agent is fatty acid or stearate emulsion.

9. The method of claim 2, wherein the dielectric material has a low dielectric constant, and is used for a single-cavity filter, the method comprising: the resistivity of the deionized water is more than 15M omega cm^-1。

Technical Field

The invention relates to the technical field of low dielectric constant dielectric materials, in particular to a low dielectric constant dielectric material for a single-cavity filter and a preparation method thereof.

Background

With the urgent need of 5G communication for ceramic filters, the research on microwave dielectric materials has become a hot direction in recent years. The microwave dielectric ceramic is used as a dielectric material in a microwave frequency band circuit and can complete one or more functions, is mainly used as microwave components such as a resonator, a filter, a dielectric antenna, a dielectric guided wave loop and the like, and can be used in the aspects of mobile communication, satellite communication, military radar and the like.

At present, the low dielectric microwave dielectric ceramic material mainly has three systems: a glass ceramics system: microcrystalline glass or amorphous glass is used, such as: CaO-B₂O₃-SiO₂Microcrystalline glass, MgO-Al₂O₃-SiO₂Is microcrystalline glass, BaO-Al₂O₃-SiO₂Microcrystalline glass and Li₂O-Al₂O₃-SiO₂Microcrystalline glass; the glass/ceramic is made of a high melting point ceramic material such as Al₂O₃、AlN、SiO₂The mixture or the mixture thereof is formed by adding a low-softening-point glass phase; the main crystal phase forms a low dielectric constant ceramic material. These systems vary depending on the use of the material. Generally, low softening point glasses in glass/ceramic LTCC materials act as a fluxing agent, facilitating densification of multiphase ceramic composites; the ceramic filler is used to improve mechanical strength, insulation property of the substrate, and to prevent warpage due to surface tension of glass during sintering.

However, the preparation method in the prior art is complex, and the quality factor and the flexural strength of the obtained low dielectric constant dielectric material cannot meet the application requirements.

Disclosure of Invention

The invention aims to provide a low dielectric constant dielectric material for a single-cavity filter and a preparation method thereof, and aims to provide a low dielectric constant dielectric material with high quality factor and high flexural strength; the other purpose is to provide a preparation method which is simple in preparation, easy in raw material obtaining, and capable of realizing large-scale production and cost reduction.

In order to achieve the purpose, the invention adopts the following technical scheme:

a low dielectric constant dielectric material for a single-cavity filter, the structure of the low dielectric constant dielectric material is (1-z/2) Mg₂SiO₄-(z/2)M₂SiO₄-mCa_（x/2）Ln_(2/3-x/3)TiO₃-ySnO₂-(0.05～0.15)wt%AF；

The QF value is larger than 52000GHz, the relative dielectric constant Epsilon is 7.5, the value of the temperature coefficient of the resonance frequency within-40-125 ℃ is smaller than 4 ppm/DEG C, and the flexural strength is larger than 320 MPa;

the range of x is 0.2 to 0.4, the range of y is 0.01 to 0.04, the range of z is 0.05 to 0.18, and the range of m is 0.03 to 0.12.

A preparation method of a low dielectric constant dielectric material for a single-cavity filter comprises the following steps:

step 1: ca_（x/2）Ln_(2/3-x/3)TiO₃Preparation of the crystalline phase:

accurately weighing 1 part of titanium dioxide, (x/2) part of calcium carbonate, (2/6-x/6) part of lanthanide oxide and 40 parts of deionized water according to molar parts, adding the weighed materials into a ball mill, grinding the materials until D50=0.5 +/-0.1 mu m and D90=1.0 +/-0.2 mu m to obtain a ball grinding material, carrying out spray drying on the ball grinding material, then carrying out heat preservation for 6 +/-2 h at 1120 +/-30 ℃, and naturally cooling to obtain Ca_（x/2）Ln_(2/3-x/3)TiO₃A crystalline phase;

step 2: ingredients

Accurately weighing (2-z) parts of magnesium hydroxide, 1 part of anhydrous silicic acid, z parts of transition metal hydroxide, y parts of stannic oxide and m parts of Ca according to molar parts_（x/2）Ln_(2/3-x/3)TiO₃Crystallizing to obtain a mixture of ingredients;

and step 3: one-time grinding

Uniformly dispersing the ingredient mixture, deionized water which is 2 times of the weight of the ingredient mixture and a dispersing agent which is 0.5% of the weight of the ingredient mixture at a high speed by adopting a sand grinding mode, and then grinding until D50=0.2 +/-0.1 mu m and D90=0.4 +/-0.2 mu m to obtain primary slurry;

and 4, step 4: spray drying

Spray drying the primary slurry material by adopting a pressure type spray drying tower to obtain a dried material;

and 5: baked block

Keeping the temperature of the dried material at the actual temperature of 1080 +/-30 ℃ for 6 +/-2 hours, and naturally cooling to obtain a sintered material;

step 6: secondary grinding

Crushing the baked materials, sieving the crushed baked materials with a 40-mesh sieve, accurately weighing the baked materials which pass through the 40-mesh sieve, meanwhile weighing 0.05 to 0.15 percent of fluoride, weighing 80 percent of deionized water and 0.5 percent of dispersant, stirring and uniformly dispersing the baked materials, the deionized water and the dispersant which pass through the 40-mesh sieve, and then sanding the mixture until D50=0.8 +/-0.1 mu m and D90=1.5 +/-0.25 mu m to obtain secondary slurry;

and 7: spray granulation

Adding a PVA solution with the weight fraction of 16% into the secondary slurry, wherein the adding amount is 12% + -4% of the weight of the clinker which passes through the 40-mesh sieve in the step 6, and simultaneously adding a release agent with the weight of 0.5% of the weight of the clinker which passes through the 40-mesh sieve in the step 6; and after uniformly stirring, carrying out spray granulation on the slurry, and sieving the slurry by a sieve of 60 meshes to remove coarse powder and a sieve of 250 meshes to remove fine powder to obtain a granulation material of 60 meshes to 250 meshes, namely the low dielectric constant dielectric material.

Preferably, the transition metal hydroxide is a transition metal cation Zn²⁺、Mn²⁺、Co²⁺、Ni²⁺、Cu²⁺At least one of the hydroxides of (1).

Further, the lanthanide oxide is at least one of lanthanum oxide, samarium oxide, neodymium oxide and praseodymium oxide.

Specifically, the transition metal hydroxide, lanthanide oxide, magnesium hydroxide and calcium carbonate all had particle sizes <0.5 microns and purities > 99.5%.

Preferably, the fluoride is at least one of magnesium fluoride, lithium fluoride, zinc fluoride or calcium fluoride.

Specifically, the dispersant is a polycarboxylate dispersant.

In some embodiments, the release agent is a fatty acid or stearate emulsion.

Further, the resistivity of the deionized water is more than 15M omega cm^-1。

Compared with the prior art, one of the technical schemes has the following beneficial effects:

1. with Mg₂SiO₄Based on the material, Ca is added_（x/2）Ln_(2/3-x/3)TiO₃Adding an A-substituted hydroxide material capable of improving the stability of the system and increasing the quality factor, and adding a B-substituted oxide material tin dioxide capable of improving the flexural strength of the system; compared with dielectric ceramic materials with similar or same dielectric constants, the dielectric material with low dielectric constant has lower temperature coefficient of resonance frequency and higher quality factor, the quality factor is superior to that of the existing publicly reported and commercially available dielectric materials under the same condition, and further, the dielectric material is more uniform in microcosmic, the consistency of dry pressing forming size is better controlled, and the grain size of a ceramic crystal phase is smaller;

2. during secondary grinding, fluoride is added as a sintering aid, so that the temperature of a burning block in the preparation process of the low-dielectric-constant dielectric material is reduced, the sintering temperature during porcelain forming is reduced, and the compactness of the ceramic material is improved.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments.

In order to facilitate an understanding of the present invention, a more complete description of the present invention is provided below. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

A low dielectric constant dielectric material for a single-cavity filter, the structure of the low dielectric constant dielectric material is (1-z/2) Mg₂SiO₄-(z/2)M₂SiO₄-mCa_（x/2）Ln_(2/3-x/3)TiO₃-ySnO₂- (0.05-0.15) wt% AF; wherein AF is fluoride, A is A site element (metal element) corresponding to fluoride, and M is transition metal element;

the QF value is larger than 52000GHz, the relative dielectric constant Epsilon is 7.5, the value of the temperature coefficient of the resonance frequency within-40-125 ℃ is smaller than 4 ppm/DEG C, and the flexural strength is larger than 320 MPa;

the range of x is 0.2 to 0.4, the range of y is 0.01 to 0.04, the range of z is 0.05 to 0.18, and the range of m is 0.03 to 0.12.

With Mg₂SiO₄Based on the material, Ca is added_（x/2）Ln_(2/3-x/3)TiO₃Adding an A-substituted hydroxide material capable of improving the stability of the system and increasing the quality factor, and adding a B-substituted oxide material tin dioxide capable of improving the flexural strength of the system; compared with dielectric ceramic materials with similar or identical dielectric constants, the dielectric material with low dielectric constant has lower temperature coefficient of resonance frequency and higher quality factor, the quality factor is superior to that of the existing publicly reported and commercially available dielectric materials under the same condition, and further, the dielectric material is more uniform in microcosmic, better controlled in consistency of dry pressing forming size and smaller in grain size of a ceramic crystal phase.

Examples 1 to 5

A low dielectric constant dielectric material for a single-cavity filter is prepared by accurately weighing 1 part of titanium dioxide, (x/2) part of calcium carbonate, (2/6-x/6) part of lanthanide oxide and 40 parts of deionized water according to mole fraction, adding the weighed materials into a ball mill, grinding the materials until D50=0.5 μm and D90=1.0 μm to obtain a ball grinding material, spray-drying the ball grinding material, preserving heat for 6 +/-2 hours at 1120 +/-30 ℃, and naturally cooling to obtain Ca_（x/2）Ln_(2/3-x/3)TiO₃Weighing (2-z) parts of magnesium hydroxide, 1 part of anhydrous silicic acid, z parts of transition metal hydroxide, y parts of stannic oxide and m parts of Ca_（x/2）Ln_(2/3-x/3)TiO₃Crystallizing to obtain a mixture of ingredients, wherein x, y, z and m values are shown in the following table, the mixture of ingredients, deionized water which is 2 times of the weight of the mixture of ingredients and a dispersing agent which is 0.5% of the weight of the mixture of ingredients are uniformly dispersed at a high speed, the speed is generally set to 25-60RPM, then the mixture of ingredients and the dispersing agent is sanded to D50=0.2 μm and D90=0.4 μm to obtain a primary slurry material, the primary slurry material is spray-dried by a pressure type spray drying tower to obtain a dried material, the dried material is kept at the actual temperature of 1080 ℃ for 6 hours, a baked block is obtained after natural cooling, the baked block is crushed and is sieved by a 40-mesh sieve, the weight of the baked block which is sieved by the 40-mesh sieve is accurately weighed, meanwhile, 0.05% -0.1% of fluoride which is weighed, 80% of deionized water and 0.5% of the dispersing agent are weighed, and the baked block, deionized water and the baked block which are sieved by the 40-mesh sieve, the deionized water and the dispersed by the 40-mesh sieve, Stirring and uniformly dispersing the dispersing agent, then sanding until D50=0.8 μm and D90=1.5 μm to obtain secondary slurry, adding a PVA solution with a weight fraction of 16% into the secondary slurry, adding 12% of the weight of the baked block passing through a 40-mesh sieve, and simultaneously adding a release agent with the weight of 0.5% of the weight of the baked block passing through the 40-mesh sieve in the step 6; and after uniformly stirring, carrying out spray granulation on the slurry, and sieving the slurry by a sieve of 60 meshes to remove coarse powder and a sieve of 250 meshes to remove fine powder to obtain a granulation material of 60 meshes to 250 meshes, namely the low dielectric constant dielectric material.

During secondary grinding, fluoride is added as a sintering aid, so that the temperature of a burning block in the preparation process of the low-dielectric-constant dielectric material is reduced, the sintering temperature during porcelain forming is reduced, the compactness of the ceramic material is improved, and the quality factor of the ceramic material is stably improved by adopting a proper sintering process; the dielectric material is proved to be good in silver adhesion after being made into porcelain through metallization, the silver layer is proved to be free from falling off when the silver layer is tested at the same position of the adhesive tape under the same silver paste and metallization under the same condition, the dielectric material is superior to a K8 ceramic material adopted by the existing filter, the preparation method of the dielectric material with the low dielectric constant is simple, the raw materials are easy to obtain, large-scale production can be achieved, and the preparation cost is low.

Some of the test data are as follows:

the following is illustrated by specific test methods:

the electrical property test method comprises the following steps: the low dielectric constant dielectric materials for single-cavity filters prepared in examples 1 to 5 were respectively subjected to dry pressing and sintering to prepare small wafers (+ -0.05 mm tolerance) having a diameter of 12mm and a height of 6 mm; the sintering process comprises the steps of adjusting the room temperature to 300 ℃ for 4 hours, 300 ℃ to 400 ℃ for 5 hours, 400 ℃ to 650 ℃ for 3 hours, 650 ℃ for 1 hour, 650 ℃ to 1240 +/-20 ℃ for 5 hours, then cooling along with a furnace, and finally testing the electrical properties at different temperatures by adopting an Agilent network analyzer, a constant temperature and humidity test box, a microwave test tool of Xiamen university and test software (parallel plate short circuit method).

And (3) testing the breaking strength: the test method of the bending strength of GB/T6569-2006 fine ceramic is adopted, namely, the low-dielectric-constant dielectric material is used for manufacturing a standard ceramic sample strip after dry pressing and sintering, a three-point method is adopted, a universal testing machine is used for reading the maximum pressure value (the breaking stress of a test strip), and then the standard working hour is used for calculation.

Metallization test adhesion test: printing the same 75% silver paste page on a standard sheet by adopting a screen printing method, preserving heat at 850 ℃ for 20min, sintering, detecting the thickness of a silver layer to be 8-9 mu M, and then testing by adopting a check method (the width of a knife edge is 10-12 mm, each 1-1.2 mm is an interval, the total number is 10, when the straight line is drawn, 10 straight line knife marks with the same interval appear, the straight line knife marks are drawn at the vertical position of the straight line knife marks to form a 100-check square of 10 x 10, when the check knife is drawn, a substrate is seen, only the silver layer can not be cut, adopting a 3M 6001 ROLL adhesive tape to be stuck at the check position, pressing the adhesive tape tightly by fingers, standing for 1min, tearing the adhesive tape by an instant force, and visually observing whether the silver layer falls off or not); tests show that the silver layer does not fall off after the same adhesive tape is tested for multiple times at the same position, and the dielectric materials of the low dielectric constant dielectric materials prepared in the examples 1-5 are superior to K8 ceramic materials adopted by the existing filters.

In this embodiment, the transition metal hydroxide is a transition metal cation Zn²⁺、Mn²⁺、Co²⁺、Ni²⁺、Cu^{2 +}The transition metal cations can improve the system stability and increase the quality factor of the A-substituted hydroxide material. Further, the lanthanide oxide is at least one of lanthanum oxide, samarium oxide, neodymium oxide and praseodymium oxide. Specifically, the particle diameters of the transition metal hydroxide, lanthanide oxide, magnesium hydroxide and calcium carbonate are all<0.5 micron and has the same purity>99.5 percent, thereby leading the purity of the crystal phase to be higher, leading the doping amount to be less, and increasing the compactness of the material and improving the quality factor. Preferably, the fluoride is at least one of magnesium fluoride, lithium fluoride, zinc fluoride or calcium fluoride, which is used as a sintering aid and has little influence on the electrical property of the system. Specifically, the dispersant is a polycarboxylate dispersant, and in this embodiment, the dispersant is preferably at least one of sannopiles type 5020, SF8, BYK type BYK190, BYK110, BYK103, BYK154, and BYK 160. In some embodiments, the release agent is a fatty acid or stearate emulsion, and the release agent is preferably at least one of a vegetable oil emulsion, a fatty acid ammonium salt emulsion, a stearic acid emulsion, and a glyceryl stearate emulsion. Further, the resistivity of the deionized water is more than 15M omega cm^-1Thereby limiting the ion content in water and ensuring the accuracy of the formula. Specifically, the inner wall and the rotor of the sand mill are made of zirconia materials, the stirring tank is made of 304 stainless steel materials, and the sand mill and the stirring tank are provided with a rust removal device in the material transfer process.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.