Li-based ultra-low dielectric silicate microwave dielectric ceramic and preparation method thereof

Abstract

The application provides a Li-based ultra-low dielectric silicate microwave dielectric ceramic, which is prepared from a compound with a chemical formula of xK2O-yLi2O-zMO2-kSiO2 (M=Ti, Zr, Hf, Sn), and the main crystal phase of the Li-based ultra-low dielectric silicate microwave dielectric ceramic has a chemical formula of KLi3M2Si 12 O 30 (M=Ti, Zr, Hf, Sn). The Li-based ultra-low dielectric silicate microwave dielectric ceramic prepared by the above method overcomes the defects in the prior art, has a sintering temperature lower than 950 DEG C and does not contain a glass phase component, has the characteristics of an ultra-low dielectric constant and a high quality factor, has the advantages of a simple synthesis process, stable main crystal phase component and low raw material price, and is a low-dielectric microwave dielectric ceramic material suitable for millimeter wave communication.

Description

Technical Field

[0001] This invention relates to the field of low-dielectric microwave dielectric ceramics, and more particularly to a Li-based ultra-low-dielectric silicate microwave dielectric ceramic and its preparation method. Background Technology

[0002] Microwave dielectric ceramics refer to ceramic materials used as dielectrics in microwave frequency bands (300MHz~3000GHz) circuits. As the operating frequency of communication equipment continues to increase, signal delay becomes more pronounced, system losses and heat generation increase accordingly, and system stability gradually deteriorates. A low dielectric constant can reduce the interaction coupling loss between the material and electrodes and improve the transmission rate of electrical signals. A superior quality factor can reduce system losses and improve the frequency selectivity of the material. Low-temperature co-fired ceramics (LTCC) technology is a novel multilayer substrate process technology that emerged in the mid-1980s. Due to its low sintering temperature (below 950℃), it can be co-fired with metal conductors, thereby improving the performance of electronic devices. Simultaneously, the unique multilayer co-firing process greatly reduces process complexity and improves component reliability. The advent of low-temperature co-firing technology has led to the rapid development of miniaturization, multifunctionality, high-frequency operation, and high reliability of microwave components. With the arrival of the 5G era, the development of 5G communication places even more stringent requirements on LTCC materials used in electronic components. In particular, the upcoming millimeter-wave and terahertz communications will create a huge demand for LTCC materials with ultra-low dielectric constants.

[0003] Currently, LTCC materials are mainly composed of two types of materials: glass-ceramic and "glass + ceramic". LTCC materials currently contain a large amount of amorphous glass. The introduction of the glass phase reduces the sintering temperature of LTCC materials to below 950℃, but the introduction of glass will greatly deteriorate the microwave dielectric properties of the material.

[0004] In view of this, it is necessary to design an improved method for preparing ultra-low dielectric silicon-based microwave dielectric ceramics that do not contain a glass phase and are sintered at low temperatures, in order to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing Li-based ultra-low dielectric silicate microwave dielectric ceramics. The Li-based silicate microwave dielectric ceramics prepared by this method have a sintering temperature below 950°C and exhibit ultra-low dielectric constant and quality factor. The development of this Li-based ultra-low dielectric silicate microwave dielectric ceramic broadens the selection range of low dielectric constant microwave dielectric ceramic materials.

[0006] To achieve the above-mentioned invention object, the present invention provides a Li-based ultra-low dielectric silicate microwave dielectric ceramic, which is prepared from a compound with the chemical formula of xK2O-yLi2O-zMO2-kSiO2, where M is one of Ti, Zr, Hf, and Sn, 0.5≤x≤1.0, 1.5≤y≤2.0, 1.5<z≤2.0, 11≤k≤12, and the chemical expression of the main crystal phase of the Li-based ultra-low dielectric silicate microwave dielectric ceramic is KLi3M2Si 12 O 30 .

[0007] Preferably, x = 0.5, y = 1.5, z = 2.0, k = 12.

[0008] Preferably, the dielectric constant ε of the Li-based ultra-low dielectric silicate microwave dielectric ceramic r is 4.0 to 5.8, and the quality factor Q×f is 4550 to 22400 GHz.

[0009] The present invention provides a preparation method of a Li-based ultra-low dielectric silicate microwave dielectric ceramic, including the following steps:

[0010] S1. Weigh the raw materials of K2CO3, Li2CO3, MO2 and SiO2 and配料 according to the stoichiometric ratio of the chemical formula xK2O-yLi2O-zMO2-kSiO2, mix them evenly, conduct the first wet ball milling treatment, and then dry and pre-burn them to obtain pre-burned ceramic powder; where M is one of Ti, Zr, Hf, and Sn, 0.5≤x≤1.0, 1.5≤y≤2.0, 1.5<z≤2.0, 11≤k≤12;

[0011] S2. Conduct the second wet ball milling treatment on the pre-burned ceramic powder obtained in step S1, dry it after ball milling treatment, add a binder for granulation, and sinter it after pressing to obtain a Li-based ultra-low dielectric silicate microwave dielectric ceramic.

[0012] Preferably, in step S1, the pre-burning temperature is 600 to 850 °C, and the pre-burning time is 5 to 10 h.

[0013] Preferably, in step S2, the sintering temperature is 875 to 950 °C, and the sintering time is 5 to 10 h.

[0014] Preferably, in step S1, the dispersant for the first wet ball milling treatment is 200 wt% of absolute ethanol, the ball milling medium is zirconia balls, the ball milling speed is 360 r / min, and the ball milling time is 5 to 10 h.

[0015] It should be noted that there is a misspelling in the original text "配料" which should be "配料", and the translation has been corrected accordingly.Preferably, in step S2, the dispersant for the second wet ball milling treatment is 200 wt% anhydrous ethanol.

[0016] Preferably, in step S2, the adhesive is PVA or paraffin.

[0017] Preferably, in step S2, the amount of the binder added is 5-10% of the mass ratio of the ceramic powder.

[0018] Preferably, in step S2, the milling medium for the second wet ball milling treatment is zirconium balls, and the ball milling process is to mill at a speed of 360 r / min for 5 to 10 hours.

[0019] The beneficial effects of this invention are:

[0020] The Li-based ultra-low dielectric silicate microwave dielectric ceramic provided by this invention uses a compound with the chemical formula xK2O-yLi2O-zMO2-kSiO2 (M=Ti,Zr,Hf,Sn) to prepare Li-based silicate microwave dielectric ceramics. This method overcomes the defects in the prior art of preparing ultra-low dielectric constant microwave dielectric ceramics at low sintering temperatures. The resulting Li-based ultra-low dielectric silicate microwave dielectric ceramic simultaneously possesses the characteristics of low sintering temperature, ultra-low dielectric constant, and excellent quality factor. The low dielectric constant reduces the interactive coupling loss between the material and the electrode and improves the transmission rate of electrical signals. The excellent quality factor reduces system losses and improves the frequency selectivity of the material. Furthermore, KLi3M2Si... 12 O 30 Li-based silicate microwave dielectric ceramics with (M=Ti,Zr,Hf,Sn) phase as the main crystalline phase have the advantages of stable main phase composition, good batch stability, low raw material price and suitability for large-scale production. They have comprehensive performance superior to existing commercial materials and are a material with great application prospects. Attached Figure Description

[0021] Figure 1 These are sintered sample images of Li-based ultra-low dielectric silicate microwave dielectric ceramics from Examples 1-14 of the present invention.

[0022] Figure 2 The ultra-low dielectric KLi3Zr2Si of Embodiment 1 of the present invention 12 O 30 A schematic diagram of the crystal structure of the main crystalline phase of microwave dielectric ceramics;

[0023] Figure 3 The ultra-low dielectric KLi3M2Si of Examples 1-4 of the present invention 12 O 30XRD patterns of microwave dielectric ceramics with (M = Ti, Zr, Hf, Sn);

[0024] Figure 4 XRD patterns of the ultra-low dielectric xK2O-yLi2O-zZrO2-kSiO2 microwave dielectric ceramics of Examples 5-14 of the present invention. Detailed implementation manners

[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Here, it should also be noted that in order to avoid obscuring the present invention due to unnecessary details, only the structures and / or processing steps closely related to the solution of the present invention are shown in the drawings, and other details less related to the present invention are omitted.

[0027] In addition, it should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0028] The present invention provides an application of a compound in the preparation of Li-based ultra-low dielectric silicate microwave dielectric ceramics. The chemical formula of the above compound is xK2O-yLi2O-zMO2-kSiO2 (M = Ti, Zr, Hf, Sn), where 0.5 ≤ x ≤ 1.0, 1.5 ≤ y ≤ 2.0, 1.5 < z ≤ 2.0, 11 ≤ k ≤ 12, and the chemical expression of the main crystal phase of the Li-based ultra-low dielectric silicate microwave dielectric ceramics is KLi3M2Si 12 O 30 , where M is one of Ti, Zr, Hf, Sn, 0.5 ≤ x ≤ 1.0, 1.5 ≤ y ≤ 2.0, 1.5 < z ≤ 2.0, 11 ≤ k ≤ 12. The dielectric constant ε of the microwave dielectric ceramic material prepared by applying the above compound r is 4.0 to 5.8, and the quality factor Q×f is 4550 to 22400 GHz.

[0029] The present invention provides a method for preparing microwave dielectric ceramics by applying the compound with the above chemical expression KLi3M2Si 12 O 30 (M = Ti, Zr, Hf, Sn). The specific preparation method is as follows:

[0030] S1. Weigh the raw materials of K2CO3, Li2CO3, MO2 (M = Ti, Zr, Hf, Sn) and SiO2 and配料 according to the stoichiometric ratio of the chemical formula xK2O-yLi2O-zMO2-kSiO2. After mixing evenly, conduct the first wet ball milling treatment, and then dry and pre-burn to obtain the pre-burned ceramic powder. Among them, M is one of Ti, Zr, Hf, Sn, 0.5 ≤ x ≤ 1.0, 1.5 ≤ y ≤ 2.0, 1.5 < z ≤ 2.0, 11 ≤ k ≤ 12; preferably, x = 0.5, y = 1.5, z = 2.0, k = 12.

[0031] S2. Conduct the second wet ball milling treatment on the pre-burned ceramic powder obtained in step S1. After ball milling, dry and add a binder for granulation. After pressing, sinter to obtain the silicon-based microwave dielectric ceramic.

[0032] Among them, in step S1, the dispersant for the first wet ball milling treatment is anhydrous ethanol with a content of 200wt%, that is, the amount of anhydrous ethanol used is twice the mass of the ceramic powder; the ball milling medium is zirconia balls, the ball milling speed is 360r / min, and the ball milling time is 5 - 10h.

[0033] In step S1, the pre-burning temperature is 600 - 850°C, and the pre-burning time is 5 - 10h.

[0034] In step S2, the dispersant for the second wet ball milling treatment is anhydrous ethanol with a content of 200wt%, the ball milling medium is zirconia balls, and the ball milling process is to ball mill at a speed of 360r / min for 5 - 10h.

[0035] In step S2, the binder is PVA (polyvinyl alcohol) or paraffin, and the mass ratio of the binder added during the granulation process to the ceramic powder is 5 - 10%.

[0036] The sintering treatment temperature is 875 - 950°C, and the sintering time is 5 - 10h.

[0037] The following further illustrates the preparation method of the silicon-based microwave dielectric ceramic with ultra-low dielectric constant of the present invention in combination with specific embodiments:

[0038] Example 1

[0039] This example prepared a Li-based ultra-low dielectric silicate microwave dielectric ceramic. The specific preparation method is as follows:

[0040] S1. K2CO3, Li2CO3, ZrO2, and SiO2 with a purity of 99.9% were mixed according to the stoichiometric ratio of xK2O-yLi2O-zZrO2-kSiO2, where x = 0.5, y = 1.5, z = 2.0, and k = 12. After uniform mixing, the powder was mixed and stirred in a ball mill for 5 hours at a speed of 360 r / min using zirconium balls as the ball milling medium and anhydrous ethanol as the dispersant. The resulting slurry was dried and pre-fired at 700℃ for 5 hours to obtain pre-fired ceramic powder.

[0041] S2. The pre-fired ceramic powder obtained in step S1 is subjected to a second wet ball milling treatment. After ball milling, it is dried to obtain ceramic powder. Then, 8% by mass of polyvinyl alcohol is added to the ceramic powder as a binder for granulation. The powder is pressed into cylindrical green samples with a thickness-to-diameter ratio of 0.4 to 0.6 under a pressure of 150 MPa. After pressing, the green samples are sintered in air at 875 to 950°C for 5 hours to obtain silicon-based microwave dielectric ceramic. The conditions of the second wet ball milling treatment are the same as those of the first wet ball milling treatment.

[0042] The sintered sample image of the Li-based ultra-low dielectric silicate microwave dielectric ceramic prepared in this embodiment is shown below. Figure 1 As shown, the sintered sample exhibits good ceramic-forming properties; Figure 2 As shown, KLi3Zr2Si 12 O 30 The presence of numerous tetrahedral six-membered ring structures in the crystal structure indicates a high proportion of Si-O bonds in Li-based ultra-low dielectric silicate microwave dielectric ceramics, suggesting that they may possess a low dielectric constant.

[0043] Examples 2 to 14

[0044] The differences between Examples 2 to 14 and Example 1 are only in the values ​​of x, y, z, and k in the compound, the M element, and the sintering temperature. The other steps are basically the same as in Example 1 and will not be repeated here. The properties of the silicon-based microwave dielectric ceramics prepared in Examples 1 to 14 are shown in Table 1. The Li-based ultra-low dielectric silicate microwave dielectric ceramics have a dielectric constant ε... r The GHz band is 4.0–5.8, and the quality factor Q×f is 4550–22400 GHz; due to KLi3M2Si 12 O 30 The (M=Ti,Zr,Hf,Sn) phase has a silicon-oxygen tetrahedral ring in its crystal structure, thus exhibiting good thermal stability; secondly, KLi3M2Si 12 O 30Silicon-based microwave dielectric ceramics with (M=Ti,Zr,Hf,Sn) as the main crystalline phase do not contain easily variable valence elements, are not prone to deliquescence, and have a low sintering temperature, thus making them a candidate material for the preparation of dielectric components and for use in electronic packaging.

[0045] Table 1. Performance comparison of silicon-based microwave dielectric ceramics prepared in Examples 1 to 14

[0046]

[0047]

[0048] like Figure 3 and 4 As shown, the main crystalline phase of the Li-based ultra-low dielectric silicate microwave dielectric ceramic prepared in this embodiment of the invention is KLi3M2Si. 12 O 30 (M=Ti,Zr,Hf,Sn), and the phase composition has no glass phase, the phase composition is stable, the ceramic sintering temperature is low, and it is suitable for mass production.

[0049] In summary, the Li-based ultra-low dielectric silicate microwave dielectric ceramic proposed in this invention uses a compound with the chemical formula xK2O-yLi2O-zMO2-kSiO2 to prepare silicon-based microwave dielectric ceramics. The resulting Li-based ultra-low dielectric silicate microwave dielectric ceramics possess both ultra-low dielectric constant and excellent quality factor, exhibiting superior overall performance compared to existing commercial materials, making it a material with great application potential.

[0050] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A Li-based ultra-low dielectric silicate microwave dielectric ceramic, characterized in that, The Li-based ultra-low dielectric silicate microwave dielectric ceramic adopts the chemical formula […]. x K2O -y Li2O -zM O2 -k The compound was prepared from SiO2, wherein 0.5 ≤ x ≤1.0, 1.5≤ y ≤2.0, 1.5< z ≤2.0, 11≤ k ≤12, and the chemical formula of the main crystal phase of the Li-based ultra-low dielectric silicate microwave dielectric ceramic is KLi3. M 2Si 12 O 30 ,in, M It is one of Ti, Zr, Hf, and Sn, and the phase composition does not include a glassy phase.

2. The Li-based ultra-low dielectric silicate microwave dielectric ceramic according to claim 1, characterized in that, x =0.5, y =1.5, z =2.0, k =12, M It is one of Ti, Zr, Hf, and Sn.

3. The Li-based ultra-low dielectric silicate microwave dielectric ceramic according to claim 1, characterized in that, The dielectric constant of the Li-based ultra-low dielectric silicate microwave dielectric ceramic ε r The quality factor is 4.0 to 5.

8. Q × f The range is 4550~22400GHz.

4. A method for preparing Li-based ultra-low dielectric silicate microwave dielectric ceramic according to any one of claims 1-3, characterized in that, Includes the following steps: S1, weigh out K2CO3, Li2CO3, M O2 and SiO2 raw materials and according to the chemical formula x K2O -y Li2O -zM O2 -k The SiO2 is stoichiometrically proportioned and mixed evenly before undergoing a first wet ball milling process. After drying and pre-firing, pre-fired ceramic powder is obtained. in, M It is one of Ti, Zr, Hf, and Sn, and 0.5 ≤ x ≤1.0, 1.5≤ y ≤2.0, 1.5< z ≤2.0, 11≤ k ≤12; S2, the pre-fired ceramic powder obtained in step S1 is subjected to a second wet ball milling process. After ball milling, it is dried, granulated with binder, pressed into tablets, and sintered to obtain Li-based ultra-low dielectric silicate microwave dielectric ceramic.

5. The method for preparing Li-based ultra-low dielectric silicate microwave dielectric ceramics according to claim 4, characterized in that, In step S1, the pre-firing temperature is 600~850℃ and the pre-firing time is 5~10h.

6. The method for preparing Li-based ultra-low dielectric silicate microwave dielectric ceramics according to claim 4, characterized in that, In step S2, the sintering temperature is 875~950℃ and the sintering time is 5~10h.

7. The method for preparing Li-based ultra-low dielectric silicate microwave dielectric ceramics according to claim 4, characterized in that, In steps S1 and S2, the dispersant used in the first and second wet ball milling processes is anhydrous ethanol, the ball milling medium is zirconium balls, and the ball milling time is 5-10 hours.

8. The method for preparing Li-based ultra-low dielectric silicate microwave dielectric ceramics according to claim 7, characterized in that, In steps S1 and S2, the amount of dispersant used is twice the mass of the powder.

9. The method for preparing Li-based ultra-low dielectric silicate microwave dielectric ceramics according to claim 4, characterized in that, In step S2, the adhesive is PVA or paraffin.

10. The method for preparing Li-based ultra-low dielectric silicate microwave dielectric ceramic according to claim 9, characterized in that, In step S2, the amount of adhesive added is 5-10% of the mass ratio of the ceramic powder.

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