Li₴O-B₴O₵-SiO₴ system glass ceramics and their preparation methods

Abstract

This invention provides a Li₂O-B₂O₃-SiO₂ system glass-ceramic, characterized in that the Li₂O-B₂O₃-SiO₂ system glass-ceramic contains 89.87~92.86 wt% SiO₂, 4.53~4.71 wt% B₂O₃ and 2.61~5.42 wt% Li₂O. This invention also provides a method for preparing the aforementioned Li₂O-B₂O₃-SiO₂ system glass-ceramics. The method comprises the following steps: mixing raw materials containing at least Li₂CO₃, H₃BO₃, and SiO₂; melting; water quenching; polishing; wet fine grinding; adding a binder; and low-temperature sintering to obtain the Li₂O-B₂O₃-SiO₂ system glass-ceramics. The raw materials are characterized by containing 6-12 wt% Li₂CO₃, 6.6-7.5 wt% H₃BO₃, and 80.5-86.5 wt% SiO₂, and the low-temperature sintering step is performed at a sintering temperature of 800-1100°C. The Li₂O-B₂O₃-SiO₂ system glass-ceramics of this invention can achieve low dielectric constant and low dielectric loss under low-temperature sintering, and their excellent material properties demonstrate their potential as low-temperature co-fired ceramics (LTCC) for use in high-frequency communication equipment.

Description

[Technical Field]

[0001] This invention relates to glass ceramics. Specifically, this invention relates to a low-temperature co-fired Li₂O-B₂O₃-SiO₂ system glass ceramic with low dielectric constant and low dielectric loss. [Previous Technology]

[0002] In recent years, low-temperature co-fired ceramics (LTCC) have been widely used in high-frequency communication equipment with characteristics such as miniaturization, high operating frequency, and low power loss. LTCC materials need to have low dielectric constant, low dielectric loss, and a suitable coefficient of thermal expansion to function effectively in these applications. A key advantage of LTCC technology is its ability to co-fire with various low-melting-point metal electrode materials (such as silver, copper, and gold) at relatively low sintering temperatures, thereby avoiding damage to components from high temperatures.

[0003] Common LTCC materials mainly include glass-ceramic systems, microcrystalline glass systems, and amorphous glass systems. Among them, glass-ceramics are not easily hydrolyzed in water or alcohol, have excellent chemical resistance, and are resistant to moisture, oxidation, and corrosion. This allows them to maintain stable performance even in harsh environments, helping to extend the lifespan of electronic components. Furthermore, glass-ceramics have the ability to produce liquid-phase sintering, and during the sintering process, a two-phase coexistence state gradually forms.

[0004] However, the main problem with LTCC technology is how to maintain the excellent microwave dielectric properties of the glass-ceramic materials produced while using low sintering temperatures. Although traditional silicate-based glass-ceramics have good high-frequency performance, they usually require high sintering temperatures, which is not conducive to LTCC applications.

[0005] To meet the requirement of maintaining dielectric properties while lowering the sintering temperature, previous studies on the modification of glass-ceramic materials have indicated that adding B₂O₃ to the Li₃Mg₂NbO₆ system can reduce the sintering temperature (Ping Zhang et al., Journal of Alloys and Compounds 2017, 690, 688-691.). In lithium silicate ceramic materials, the Li / Si molar ratio and sintering temperature are key factors in achieving ideal microwave dielectric properties (Chengli Sun et al., Journal of Materials Science: Materials in Electronics 2022, 33, 4043–4050.). CaO-B₂O₃-SiO₂ (CBS) glass-ceramic systems, dominated by the silanite phase, exhibit excellent microwave dielectric properties at high frequencies. However, their sintering temperatures are typically high, which is detrimental to LTCC applications (Chao Dong et al., Crystals 2023, 13, 748.). Furthermore, some studies have indicated that alkali metals can disrupt the glass network structure, maintaining the excellent properties of high-silica materials while reducing the viscosity of the glass melt, potentially enabling lower processing temperatures (Neetu Bansal et al., Ceramics International 2023, 49, 2998-3006.).

[0006] These studies demonstrate that alkali metals (especially lithium) and boron play a crucial role in the modification of glass-ceramics. They not only improve the melting properties of glass, thereby effectively reducing the sintering temperature, but also optimize the glass structure, enhance dielectric properties, and improve the material's adaptability in low-temperature co-firing environments, making it one of the ideal choices for meeting the low-temperature sintering requirements of LTCC. However, further optimization of the material composition of glass-ceramics is still needed to meet the stringent requirements of LTCC applications. Specifically, a glass-ceramic material that achieves an ideal balance between low sintering temperature, low dielectric constant, and high Qf value still needs to be developed. [Previous Technical References] [Previous Technical Reference 1] Ping Zhang et al., Journal of Alloys and Compounds 2017, 690, 688-691. [Previous Technical Reference 2] Chengli Sun et al., Journal of Materials Science: Materials in Electronics 2022, 33, 4043–4050. [Previous Technical Reference 3] Chao Dong et al., Crystals 2023, 13, 748. [Previous Technical Reference 4] Neetu Bansal et al., Ceramics International 2023, 49, 2998-3006. [Summary of the Invention]

[0007] [Technical Problem to be Solved by the Invention] Accordingly, the present invention provides a low-temperature co-fired ceramic, specifically, a Li₂O-B₂O₃-SiO₂ system glass-ceramic (LBS glass-ceramic) and its preparation method. Compared with traditional glass-ceramics, the Li₂O-B₂O₃-SiO₂ system glass-ceramic of the present invention can achieve low dielectric constant and low dielectric loss under low-temperature sintering. Its excellent material properties demonstrate its potential as a low-temperature co-fired ceramic (LTCC) for application in high-frequency communication equipment. [Technical Means]

[0008] In one state sample, the present invention provides a Li₂O-B₂O₃-SiO₂ system glass-ceramic, characterized in that the Li₂O-B₂O₃-SiO₂ system glass-ceramic contains 89.87~92.86 wt% SiO₂, 4.53~4.71 wt% B₂O₃ and 2.61~5.42 wt% Li₂O.

[0009] In some embodiments, the dielectric constant εᵣ of the Li₂O-B₂O₃-SiO₂ system glass ceramic is 4.7~5.4.

[0010] In some embodiments, the Qf value of the Li 2O-B 2O 3-SiO 2 system glass ceramic is 1900~2600 GHz.

[0011] In some embodiments, the micro Vickers hardness (MHV) of the Li 2O-B 2O 3-SiO 2 system glass ceramic is 190~249 kgf / mm².

[0012] In some embodiments, the density of the Li 2O-B 2O 3-SiO 2 system glass ceramic is 1.5~2.0 g / cm 3.

[0013] In some embodiments, the Li 2O-B 2O 3-SiO 2 system glass ceramic is obtained by sintering at a sintering temperature of 800~1100°C.

[0014] In another embodiment, the present invention provides a method for preparing the aforementioned Li₂O-B₂O₃-SiO₂ system glass ceramic, the method comprising the following steps: mixing raw materials containing at least Li₂CO₃, H₃BO₃ and SiO₂, melting, water quenching, polishing, wet fine grinding, adding a binder and low-temperature sintering to obtain the Li₂O-B₂O₃-SiO₂ system glass ceramic, characterized in that the raw materials contain 6~12 wt% Li₂CO₃, 6.6~7.5 wt% H₃BO₃ and 80.5~86.5 wt% SiO₂, and the low-temperature sintering step is performed at a sintering temperature of 800~1100°C.

[0015] In some embodiments, the melting step of the method is to melt in a furnace at 1500~1580°C and hold the temperature for 4 to 8 hours.

[0016] In some embodiments, the wet fine grinding step of the method is to perform wet fine grinding until the particle size is <5μm.

[0017] In some embodiments, the low-temperature sintering step of this method is performed for 1 to 4 hours. [Effects of the Invention]

[0018] The Li₂O-B₂O₃-SiO₂ system glass ceramic of the present invention effectively reduces the sintering temperature to 800°C, thereby enabling co-firing with low-melting-point metal electrodes without damaging the components. It is suitable for low-temperature co-fired ceramic (LTCC) applications and achieves many technical benefits, including maintaining a low dielectric constant (4.7~5.4) and a high Qf value (1900~2600 GHz) in the microwave frequency range, which can meet the requirements of high-frequency communication applications. At the same time, the Li₂O-B₂O₃-SiO₂ system glass ceramic of the present invention also has appropriate crystal phase, density and hardness, ensuring that it has sufficient surface hardness and chemical stability, giving it resistance to moisture, oxidation and corrosion, which helps to improve performance stability and extend component life in harsh environments.

Implementation Method

[0019] The following describes specific embodiments and examples of the present invention to make it easier for those skilled in the art to understand the technical means provided by the present invention. It should be noted that the following embodiments and examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0020] In a single state sample, the present invention uses raw materials with a specific ratio of Li 2CO 3, H 3BO 3 and SiO 2, so that the Li 2O-B 2O 3-SiO 2 system glass ceramic of the present invention, after being sintered at low temperature, still has excellent material properties such as low dielectric constant and high Qf value (representing low dielectric loss).

[0021] The Li₂O-B₂O₃-SiO₂ system glass-ceramic of the present invention comprises 89.87~92.86 wt% SiO₂, 4.53~4.71 wt% B₂O₃ and 2.61~5.42 wt% Li₂O, ideally 89.87~91.89 wt% SiO₂, 4.60~4.71 wt% B₂O₃ and 3.52~5.42 wt% Li₂O, more ideally 89.87~90.89 wt% SiO₂, 4.65~4.71 wt% B₂O₃ and 4.46~5.42 wt% Li₂O, and even more ideally about 89.87 wt% SiO₂, about 4.71 wt% B₂O₃ and about 5.42 wt% Li₂O.

[0022] The dielectric constant εᵣ of the Li 2O-B 2O 3-SiO 2 system glass ceramic of the present invention is 4.7~5.4, and ideally 4.7~5.0.

[0023] The Qf value of the Li 2O-B 2O 3-SiO 2 system glass ceramic of the present invention is 1900~2600 GHz, ideally 2300~2600 GHz.

[0024] The micro Vickers hardness (MHV) of the Li 2O-B 2O 3-SiO 2 system glass ceramic of the present invention is 190~249 kgf / mm², ideally about 249 kgf / mm².

[0025] The Li 2O-B 2O 3-SiO 2 system glass ceramic of the present invention is obtained by sintering at a sintering temperature of 800~1100℃, ideally at a sintering temperature of 900~1000℃, more ideally at a sintering temperature of 900~950℃, and even more ideally at a sintering temperature of about 900℃.

[0026] In another embodiment, the method for preparing the aforementioned Li 2O-B 2O 3-SiO 2 system glass ceramic of the present invention comprises the following steps: (1) mixing raw materials containing at least Li 2CO 3, H 3BO 3 and SiO 2: mixing powders of H 3BO 3 (6.6~7.5 wt%), SiO 2 (80.5~86.5 wt%) and Li 2CO 3 (6~12 wt%); (2) melting: then melting in a furnace at 1500~1580°C and holding at that temperature for 1 to 8 hours; (3) water quenching: then water quenching and pouring out to obtain Li 2O-B 2O 3-SiO 2 glass; (4) polishing: then using a polishing machine to pulverize the aforementioned Li 2O-B 2O 3-SiO 2 glass into glass powder; (5) Wet fine grinding: Next, water, alcohol, dispersant, etc. are added to the aforementioned glass powder for wet fine grinding until the particle size is <5μm; (6) Adding binder: Next, binder (e.g., polyvinyl alcohol (PVA)) is added and uniaxial pressure is used to form a block shape; (7) Low temperature sintering: Finally, low temperature sintering is carried out for 1 to 4 hours in the sintering temperature range of 800~1100°C to obtain Li 2O-B 2O 3-SiO 2 glass ceramic.

[0027] In the method for preparing the aforementioned Li 2O-B 2O 3-SiO 2 system glass ceramic of the present invention, the sintering temperature can be 800~1100℃, ideally 900~1000℃, more ideally 900~950℃, and even more ideally about 900℃.

[0028] In the method for preparing the aforementioned Li₂O-B₂O₃-SiO₂ system glass-ceramics according to the present invention, the raw material may contain 6~12 wt% Li₂CO₃, 6.6~7.5 wt% H₃BO₃, and 80.5~86.5 wt% SiO₂, ideally 6~12 wt% Li₂CO₃, 7.5 wt% H₃BO₃, and 80.5~86.5 wt% SiO₂, more ideally 8~12 wt% Li₂CO₃, 7.5 wt% H₃BO₃, and 80.5~84.5 wt% SiO₂, more ideally 10~12 wt% Li₂CO₃, 7.5 wt% H₃BO₃, and 80.5~82.5 wt% SiO₂, and even more ideally about 12 wt% Li₂CO₃, about 7.5 wt% H₃BO₃, and about 7.5 wt% SiO₂. wt% H 3BO 3 and approximately 80.5 wt% SiO 2.

[0029] When the raw material in the method for preparing the aforementioned Li₂O-B₂O₃-SiO₂ system glass ceramic of the present invention contains 6 wt% Li₂CO₃, 7.5 wt% H₃BO₃ and 86.5 wt% SiO₂, the resulting Li₂O-B₂O₃-SiO₂ system glass ceramic contains approximately 92.86 wt% SiO₂, approximately 4.53 wt% B₂O₃ and approximately 2.61 wt% Li₂O. When the raw material in the method for preparing the aforementioned Li₂O-B₂O₃-SiO₂ system glass ceramic of the present invention contains 8 wt% Li₂CO₃, 7.5 wt% H₃BO₃ and 84.5 wt% SiO₂, the resulting Li₂O-B₂O₃-SiO₂ system glass ceramic contains approximately 91.89 wt% SiO₂, approximately 4.60 wt% B₂O₃ and approximately 3.52 wt% Li₂O. When the raw material in the method for preparing the aforementioned Li₂O-B₂O₃-SiO₂ system glass ceramic of the present invention contains 10 wt% Li₂CO₃, 7.5 wt% H₃BO₃ and 82.5 wt% SiO₂, the resulting Li₂O-B₂O₃-SiO₂ system glass ceramic contains approximately 90.89 wt% SiO₂, approximately 4.65 wt% B₂O₃ and approximately 4.46 wt% Li₂O. When the raw material in the method for preparing the aforementioned Li₂O-B₂O₃-SiO₂ system glass-ceramics of the present invention is composed of 12 wt% Li₂CO₃, 7.5 wt% H₃BO₃, and 80.5 wt% SiO₂, the resulting Li₂O-B₂O₃-SiO₂ system glass-ceramics contain approximately 89.87 wt% SiO₂, approximately 4.71 wt% B₂O₃, and approximately 5.42 wt% Li₂O. [Example]

[0030] [Synthesis of Li₂O-B₂O₃-SiO₂ system glass ceramics]

[0031] Powders of H₃BO₃, SiO₂, and Li₂CO₃ are mixed and melted in a furnace at approximately 1500°C for 1-4 hours. The mixture is then water-quenched and poured out to obtain Li₂O-B₂O₃-SiO₂ glass. Next, the Li₂O-B₂O₃-SiO₂ glass is pulverized into glass powder using a grinder. This glass powder is then wet-milled until the particle size is <5 μm. PVA is then added as a binder and uniaxially pressure-formed into a block shape. Finally, the block is sintered at a sintering temperature of 900°C, 950°C, or 1000°C for 0.5-2 hours to obtain Li₂O-B₂O₃-SiO₂ system glass-ceramics (LBS glass-ceramics). The weight percentages of H₃BO₃, SiO₂, and Li₂CO₃ powders used in the synthesis of various Li₂O-B₂O₃-SiO₂ system glass ceramics are as follows: Li2O-B2O3-SiO2 system glass ceramics Li2CO3 (wt%) H3BO3 (wt%) SiO2 (wt%) LBS06 6 7.5 86.5 LBS08 8 7.5 84.5 LBS10 10 7.5 82.5 LBS12 12 7.5 80.5

[0032] The B₂O₃-SiO₂ glass-ceramic (BS glass-ceramic) as a comparative example was prepared by the same method, except that Li₂CO₃ was not added during the preparation of the B₂O₃-SiO₂ glass-ceramic. The weight percentages of H₃BO₃ and SiO₂ powders used in the synthesis of each B₂O₃-SiO₂ glass-ceramic are as follows: B2O3-SiO2 glass ceramic H3BO3 (wt%) SiO2 (wt%) BS7.5 7.5 92.5 BS15 15 85 BS25 25 75

[0033] The following will describe the structure, dielectric properties and mechanical properties of various LBS glass ceramics and BS glass ceramics made with different component ratios and sintering temperatures.

[0034] [Microstructure of BS glass-ceramics]

[0035] The microstructure of various BS glass-ceramics prepared at different sintering temperatures was analyzed by XRD patterns and Raman spectroscopy. As shown in Figures 1A and 1B, BS7.5, BS15 and BS25 prepared at sintering temperatures of 900℃ and 950℃ all exhibited amorphous phase structures, while those prepared at sintering temperature of 1000℃ all exhibited cristobalite phase structures, with BS7.5 showing particularly strong phase structure.

[0036] SEM images of BS glass ceramics were captured using a field-emission scanning electron microscope (FE-SEM). As shown in Figures 2A to 2I, BS7.5, BS15, and BS25, prepared at sintering temperatures of 900℃ and 950℃, maintained an amorphous phase structure in powder form. When the sintering temperature was increased to 1000℃, it was observed that with the increase of the amount of H3BO3 additive, the grains of BS glass ceramics grew significantly, and their density increased, as shown in Figure 3C.

[0037] [Dielectric properties of BS glass ceramic]

[0038] When SiO2 contains 50% cristobalite structure, the dielectric constant of the amorphous state increases from 3.4 to 4.4, requiring a sintering temperature of 1000℃. As shown in Figure 3B, when the sintering temperature is 900~950℃, the overall dielectric constant (εᵣ) is between 3.8 and 4.7, but the Qf value decreases. Among them, BS7.5 prepared at a sintering temperature of 1000℃ produces more cristobalite phase and has a slightly higher Qf value, reaching 1800 GHz, as shown in Figure 3A.

[0039] [Mechanical properties of BS glass ceramics]

[0040] As shown in Figure 4, the hardness of BS glass ceramics increases with the increase of sintering temperature and increases with the increase of H3BO3 additive, producing more cristobalite phase.

[0041] [Microstructure of LBS glass-ceramic]

[0042] Differential scanning calorimetry (DSC) was used to perform thermal analysis on LBS glass-ceramics. The DSC curves of the LBS glass-ceramics are shown in Figure 5A. It can be seen that the network structure of the LBS glass-ceramics is composed of [SiO₄] tetrahedra, with alkali metal and alkaline earth metal ions bonded in the network structure via non-bridging oxygen (NBO). The main factors affecting the glass transition temperature (Tg) are the changes in ionic radius and atomic bond strength. Due to the smaller radius of the Li⁺ ion, the crystallinity of the glass can be increased, and Tg and crystallization temperature (Tc) decrease with increasing Li₂CO₃ content.

[0043] Furthermore, the microstructure of each LBS glass-ceramic prepared at different sintering temperatures was analyzed by XRD patterns and Raman spectroscopy. Since LBS06 still exhibits a cristobalite structure after melting and water quenching, no further analysis was performed (not shown). The XRD patterns in Figure 5B show the formation of crystal phases in LBS08, LBS10, and LBS12 glass-ceramics, confirming that Li₂CO₃ can act as an effective nucleating agent. In addition, the quantitative results of the XRD patterns are shown in Table 1. It can be seen that as the sintering temperature increases, the quartz phase gradually decreases and is replaced by Li₂Si₂O₅ and Li₂SiO₃ phases. The Li₂SiO₃ phase begins to develop from 950 °C.

[0044] Table 1 Sintering temperature 900 ℃ 950 ℃ 1000 ℃ Glass ceramics LBS08 LBS10 LBS12 LBS08 LBS10 LBS12 LBS08 LBS10 LBS12 Quartz 100 92.9 82.7 100 98.1 93.5 100 97.3 92.4 Li2Si2O5 0 7.1 17.3 0 1.5 0 0 0 0 Li2SiO3 0 0 0 0 0.3 6.5 0 2.7 7.6

[0045] The Raman spectra of LBS08, LBS10, and LBS12 prepared at different sintering temperatures are shown in Figure 5C. LBS08 prepared at sintering temperatures of 900–1000 °C shows a quartz phase as its main phase. LBS10 and LBS12 prepared at sintering temperature of 900 °C correspond to the Li₂Si₂O₅ phase structure. When the sintering temperature is increased to 950 °C, LBS12 exhibits the Li₂SiO₃ phase. With the increase of Li₂CO₃ content, a large amount of free oxygen is provided, breaking the Si-O-Si bonds and transforming them into non-bridging oxygen atoms. This further verifies the XRD patterns and quantitative phase results.

[0046] SEM micrographs of LBS glass-ceramics are shown in Figures 6A to 6L. It can be seen that the addition of Li₂CO₃ makes the grain structure of LBS glass-ceramics sintered at a sintering temperature of 900℃ clearer. When the sintering temperature is 950℃, the grain size of LBS10 and LBS12 increases significantly due to the formation of the Li₂SiO₃ second phase. Compared with BS glass-ceramics (BS7.5), the shrinkage rate and density of LBS glass-ceramics (LBS08, LBS10, and LBS12) decrease with increasing sintering temperature. This is due to the volume expansion caused by the precipitation of the crystalline phase, which leads to a decrease in density. As shown in Figure 7C, the densities of LBS08, LBS10, and LBS12 obtained at different sintering temperatures are approximately 1.5~2.0 g / cm³.

[0047] [Dielectric properties of LBS glass-ceramic]

[0048] The Qf value and dielectric constant of LBS glass ceramics are shown in Figures 7A and 7B, respectively. The Qf value of LBS12, prepared at different sintering temperatures, is approximately 2300–2600 GHz. It can be seen that LBS08, with the addition of a small amount of Li₂CO₃, still exhibits a quartz phase, which is the reason why its electrical properties are inferior to those of LBS10 and LBS12. In contrast, the dielectric constant of LBS10 and LBS12, prepared at sintering temperatures of 900–950°C, ranges from 4.7 to 5.4, and the Qf value ranges from 1900 to 2600 GHz. LBS12, prepared at sintering temperatures of 900–1000°C, exhibits a low dielectric constant, ranging from 4.7 to 5.0, and a Qf value of approximately 2600 GHz, fully meeting the requirements of LTCC materials. It also demonstrates its highest hardness at a sintering temperature of 900°C, i.e., MHV = 249 (kgf / mm²), as shown in Figure 8. In summary, the LBS glass-ceramic preparation method of this invention, by employing a low sintering temperature of 900–950°C, can produce glass-ceramics that meet the low-temperature sintering requirements of LTCC materials. In particular, the LBS12 glass-ceramic prepared from raw materials containing 12 wt% Li₂CO₃ at a sintering temperature of 900°C possesses the optimal parameters. [Simplified Explanation of the Diagram]

[0049] [Figure 1A] Figure 1A shows the XRD patterns of comparative examples BS7.5, BS15, and BS25 obtained by the present invention at sintering temperatures of 900°C, 950°C, or 1000°C. [Figure 1B] Figure 1B shows the Raman spectra of comparative examples BS7.5, BS15, and BS25 obtained by the present invention at sintering temperatures of 900°C, 950°C, or 1000°C. [Figure 2] Figures 2A to 2I are FE-SEM micrographs of comparative examples BS7.5, BS15, and BS25 obtained by the present invention at sintering temperatures of 900°C, 950°C, or 1000°C. [Figure 3] Figure 3A shows the Qf values ​​of comparative examples BS7.5, BS15, and BS25 obtained at sintering temperatures of 900°C, 950°C, or 1000°C according to the present invention. Figure 3B shows the dielectric constants of comparative examples BS7.5, BS15, and BS25 obtained at sintering temperatures of 900°C, 950°C, or 1000°C. Figure 3C shows the densities of comparative examples BS7.5, BS15, and BS25 obtained at sintering temperatures of 900°C, 950°C, or 1000°C. [Figure 4] Figure 4 shows the micro Vickers hardness (MHV) values ​​of comparative examples BS7.5, BS15, and BS25 obtained at sintering temperatures of 900°C, 950°C, or 1000°C. [Figure 5A] Figure 5A shows the DSC curves of Examples LBS08, LBS10, and LBS12 obtained by the present invention at sintering temperatures of 900°C, 950°C, or 1000°C. [Figure 5B] Figure 5B shows the XRD patterns of Examples LBS08, LBS10, and LBS12 obtained by the present invention at sintering temperatures of 900°C, 950°C, or 1000°C. [Figure 5C] Figure 5C shows the Raman spectra of Examples LBS08, LBS10, and LBS12 obtained by the present invention at sintering temperatures of 900°C, 950°C, or 1000°C. [Figure 6] Figures 6A to 6L are FE-SEM micrographs of Examples LBS08, LBS10, LBS12, and Comparative Example BS7.5 obtained by the present invention at sintering temperatures of 900°C, 950°C, or 1000°C. [Figure 7] Figure 7A shows the Qf values ​​of Examples LBS08, LBS10, LBS12 and Comparative Example BS7.5 obtained by sintering at 900°C, 950°C or 1000°C according to the present invention. Figure 7B shows the dielectric constants of Examples LBS08, LBS10, LBS12 and Comparative Example BS7.5 obtained by sintering at 900°C, 950°C or 1000°C. Figure 7C shows the densities of Examples LBS08, LBS10, LBS12 and Comparative Example BS7.5 obtained by sintering at 900°C, 950°C or 1000°C.[Figure 8] Figure 8 shows the micro Vickers hardness (MHV) values ​​of Examples LBS08, LBS10 and LBS12 obtained at sintering temperatures of 900°C, 950°C or 1000°C.

Claims

1. A Li2O-B2O3-SiO2 system glass-ceramic, characterized in that the Li2O-B2O3-SiO2 system glass-ceramic comprises 89.87~92.86 wt% SiO2, 4.53~4.71 wt% B2O3 and 2.61~5.42 wt% Li2O, and the Li2O-B2O3-SiO2 system glass-ceramic is obtained by sintering at a sintering temperature of 900~1000℃.

2. The Li₂O-B₂O₃-SiO₂ system glass-ceramic as described in claim 1, wherein, The dielectric constant εᵣ of the Li₂O-B₂O₃-SiO₂ system glass ceramic is 4.7~5.

4.

3. The Li₂O-B₂O₃-SiO₂ system glass-ceramic as described in claim 1, wherein, The Qf value of the Li2O-B2O3-SiO2 system glass ceramic is 1900~2600 GHz.

4. The Li₂O-B₂O₃-SiO₂ system glass-ceramic as described in claim 1, wherein, The micro Vickers hardness (MHV) of this Li2O-B2O3-SiO2 system glass ceramic is 190~249 kgf / mm².

5. The Li₂O-B₂O₃-SiO₂ system glass-ceramic as described in claim 1, wherein, The density of the Li2O-B2O3-SiO2 system glass ceramic is 1.5~2.0 g / cm3.

6. A method for preparing the Li2O-B2O3-SiO2 system glass ceramic as described in claim 1, the method comprising the following steps: mixing raw materials containing at least Li2CO3, H3BO3 and SiO2, melting, water quenching, polishing, wet fine grinding, adding a binder and low-temperature sintering to obtain the Li2O-B2O3-SiO2 system glass ceramic, characterized in that the raw materials contain 6~12 wt% Li2CO3, 6.6~7.5 wt% H3BO3 and 80.5~86.5 wt% SiO2, and the low-temperature sintering step is performed at a sintering temperature of 900~1000°C.

7. The method as described in claim 6, wherein the melting step of the method is performed in a furnace at 1500~1580°C and held at that temperature for 4 to 8 hours.

8. The method as described in claim 6, wherein the wet fine grinding step of the method is to perform wet fine grinding until the particle size is <5 μm.

9. The method as described in claim 6, wherein the low-temperature sintering step of the method is performed for 1 to 4 hours.

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