Single crystal glass ceramics and preparation method thereof, glass powder and preparation method thereof

Abstract

The present invention provides a method for preparing single-crystal glass ceramics, a method for preparing glass powder, a glass powder, and a single-crystal glass ceramic. The method for preparing the single-crystal glass ceramics comprises the following steps: mixing the glass powder with an organic solvent, tape-casting to obtain a green ceramic tape, laminating and pressing the green ceramic tape, and then sintering the tape in a sintering furnace; the sintering process comprises: heating to 500-550°C at a rate of 1-2°C / min, holding at that temperature for 4-5 hours, then debinding; heating to 860-880°C at a rate of 3-5°C / min, holding at that temperature for 10-30 minutes; and cooling to obtain the single-crystal glass ceramics.

Description

Technical Field

[0001] The present invention belongs to the technical field of low-temperature co-fired ceramics, and in particular relates to a method for preparing single-crystal glass ceramics, a method for preparing glass powder, a glass powder, and a single-crystal glass ceramic. Background Art

[0002] Low-temperature co-fired ceramic (LTCC) technology is widely used in various electronic components due to its advantages such as miniaturization, integration, and low cost. With the rapid development of high-frequency communication technology, the requirements for the comprehensive performance of LTCC materials are constantly increasing, and the contradictions between the various properties of LTCC are becoming increasingly prominent.

[0003] The dielectric constant (K value) of existing low-k LTCC substrates typically ranges from 5 to 8, correspondingly, their flexural strength is generally around 170 MPa. However, with the miniaturization and integration of high-frequency communication technologies, LTCC substrates need to possess certain flexural and compressive strength to withstand high-load packaging environments. Furthermore, since silver (Ag) has a melting point of 961°C, the densification temperature of LTCC substrates is typically less than 900°C.

[0004] At present, the existing LTCC substrate materials are mainly microcrystalline glass systems and glass / ceramic composite systems. Among them, due to the advantages of low cost and high strength of Al2O3, the most commonly used glass / Al2O3 composite material in the glass / ceramic composite system. The existing technology (for example, Chinese invention patent CN113372005A) uses lead borosilicate glass to pre-treat the surface of α-alumina to improve the interface contact strength between glass and alumina. Specifically, the mechanical properties of lead borosilicate glass are improved by doping α-alumina with high mechanical strength (300MPa) into lead borosilicate low-melting point glass (sintering aid). However, the high dielectric constant of alumina (9.8@10MHz) will cause the dielectric constant of the material to be too high. Moreover, lead glass is not in line with environmentally friendly development. In addition, in the microcrystalline glass system, a combination of multiple glasses is usually used to coordinate the comprehensive performance of LTCC materials. However, how to use traditional formulas and simple processes to meet the appropriate sintering temperature, low dielectric constant, low dielectric loss and high bending strength required by LTCC substrates is still a problem that needs to be solved urgently in this field.

[0005] In order to overcome the above-mentioned defects of the prior art, the art urgently needs a single crystal glass ceramic and a preparation method thereof, which can balance and improve the sintering temperature, dielectric constant, dielectric loss and flexural strength of LTCC substrate materials. Summary of the Invention

[0006] The following is a brief summary of one or more aspects to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceivable aspects and is neither intended to identify key or critical elements of all aspects nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that will be provided later.

[0007] In order to overcome the above-mentioned defects of the prior art, the present invention provides a method for preparing single-crystal glass ceramics, a method for preparing glass powder, a glass powder, and a single-crystal glass ceramic, which can balance and improve the sintering temperature, dielectric constant, dielectric loss, and flexural strength of LTCC substrate materials.

[0008] Specifically, the preparation method of the above-mentioned single crystal glass ceramic provided in the first aspect of the present invention comprises the steps of: mixing glass powder with an organic solvent, obtaining a green porcelain tape by tape casting, laminating and pressing the green porcelain tape, and then sintering the green porcelain tape in a sintering furnace, wherein the glass powder comprises, by molar percentage, 41.68 to 47.2 mol% of CaO, 12.7 to 15.01 mol% of B2O3, 37.77 to 40.97 mol% of SiO2 and doped modifier ions. The modifier ions include one or more of Al2O3, Ta2O5, Nb2O5, La2O3, CeO2, CuO, and BaO, and the silicon-calcium ratio of the glass powder is 0.9 to 1; the sintering process includes: heating to 500-550°C at a rate of 1-2°C / min, keeping warm for 4-5 hours, and then debinding; heating to 860-880°C at a rate of 3-5°C / min, keeping warm for 10-30 minutes; and cooling to obtain single crystal glass ceramics.

[0009] Preferably, in one embodiment of the present invention, the sintering shrinkage of the glass powder is 15% to 18%.

[0010] Preferably, in one embodiment of the present invention, the doped modifier ion is Al2O3, and the glass powder includes 0.34 to 3 mol% of Al2O3 in terms of molar percentage.

[0011] Preferably, in one embodiment of the present invention, the preparation of the glass powder includes the steps of: preparing raw materials and fully mixing them, the raw materials including SiO2, H3BO3, CaCO3, and Al(OH)3 weighed in a stoichiometric ratio; melting the mixed raw materials, and pouring the melted glass liquid into a cooling rolling mill for rapid cooling to obtain glass sheets; placing the glass sheets into a grinder for preliminary crushing to obtain glass particles; and passing the glass particles through an air flow mill in combination with an air flow classifier to obtain glass powder within a preset particle size distribution range.

[0012] Preferably, in one embodiment of the present invention, the step of melting the mixed raw materials comprises: melting the prepared raw materials at 1350-1450° C. for 1-3 hours.

[0013] Preferably, in one embodiment of the present invention, the glass particles have a particle size range of 0.5 to 2.0 mm.

[0014] Preferably, in an embodiment of the present invention, the preset particle size distribution range of the glass powder is 3.0-4.0 μm.

[0015] According to the second aspect of the present invention, the single crystal glass ceramics are provided, and the single crystal glass ceramics are prepared by the preparation method of the single crystal glass ceramics provided by the first aspect of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above features and advantages of the present invention will be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or characteristics may have the same or similar reference numerals.

[0017] Figure 1 A flow chart showing a method for preparing glass powder according to some embodiments of the present invention is shown;

[0018] Figure 2 A flow chart showing a method for preparing single crystal glass ceramics according to some embodiments of the present invention is shown;

[0019] Figure 3 The formulas of glass powders provided according to multiple embodiments and comparative examples of the present invention are shown;

[0020] Figure 4 The performance test results of glass ceramics provided according to multiple embodiments of the present invention and multiple comparative examples are shown;

[0021] Figure 5 The bending strength of glass ceramics provided according to multiple embodiments of the present invention and multiple comparative examples is shown;

[0022] Figure 6 The figure shows an ex-situ selected area electron diffraction pattern of the glass powder provided in Example 2 according to the present invention after being sintered at 880° C. and kept warm for 30 minutes;

[0023] Figure 7 shows a microscopic morphology of the glass powder provided in Example 2 according to the present invention after sintering at 880° C. and keeping warm for 30 minutes; and

[0024] Figure 8A comparison of the XRD patterns of the single crystal glass ceramics provided in Example 1 and Comparative Example 2 of the present invention is shown.

[0025] Reference numerals:

[0026] 100: Preparation method of glass powder;

[0027] S110~S140: Steps;

[0028] 200: Preparation method of single crystal glass ceramics;

[0029] S210-S240: steps; and

[0030] 801, 802: lines. DETAILED DESCRIPTION

[0031] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Note that the various aspects described below with reference to the accompanying drawings and specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention.

[0032] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0033] Furthermore, the terms "upper," "lower," "left," "right," "top," "bottom," "horizontal," and "vertical" used in the following description should be understood to refer to the orientations depicted in that section and the accompanying drawings. These relative terms are used solely for convenience of description and do not necessarily imply that the devices described herein must be manufactured or operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0034] It will be understood that although the terms "first," "second," "third," etc. may be used herein to describe various components, regions, layers, and / or portions, these components, regions, layers, and / or portions should not be limited by these terms, and these terms are merely used to distinguish different components, regions, layers, and / or portions. Thus, a first component, region, layer, and / or portion discussed below may be referred to as a second component, region, layer, and / or portion without departing from some embodiments of the present invention.

[0035] As mentioned above, in the context of miniaturization and integration of high-frequency communication technologies, LTCC substrates must possess certain bending and compressive strength to withstand high-load packaging environments. Furthermore, since silver (Ag) has a melting point of 961°C, the densification temperature of LTCC substrates is typically less than 900°C.

[0036] At present, the existing LTCC substrate materials are mainly microcrystalline glass systems and glass / ceramic composite systems. Among them, due to the advantages of low cost and high strength of Al2O3, the most commonly used glass / Al2O3 composite material in the glass / ceramic composite system. The existing technology (for example, Chinese invention patent CN113372005A) uses lead borosilicate glass to pre-treat the surface of α-alumina to improve the interface contact strength between glass and alumina. Specifically, the mechanical properties of lead borosilicate glass are improved by doping α-alumina with high mechanical strength (300MPa) into lead borosilicate low-melting point glass (sintering aid). However, the high dielectric constant of alumina (9.8@10MHz) will cause the dielectric constant of the material to be too high. Moreover, lead glass is not in line with environmentally friendly development. In addition, in the microcrystalline glass system, a combination of multiple glasses is usually used to coordinate the comprehensive performance of LTCC materials. However, how to use traditional formulas and simple processes to meet the appropriate sintering temperature, low dielectric constant, low dielectric loss and high bending strength required by LTCC substrates is still a problem that needs to be solved urgently in this field.

[0037] In order to overcome the above-mentioned defects of the prior art, the present invention provides a method for preparing single-crystal glass ceramics, a method for preparing glass powder, a glass powder, and a single-crystal glass ceramic, which can balance and improve the sintering temperature, dielectric constant, dielectric loss, and flexural strength of LTCC substrate materials.

[0038] The glass powder described above will be described below, first with reference to several examples of glass powder preparation methods. Those skilled in the art will appreciate that these examples of glass powder preparation methods are merely non-limiting implementations of the present invention, intended to clearly illustrate the main concepts of the present invention and provide specific solutions for easy implementation. Similarly, these glass powder preparation methods do not limit the execution of the various steps in these glass powder preparation methods, nor do they limit their execution order.

[0039] The glass powder for LTCC provided by the present invention is based on the CaO-B2O3-SiO2 (CBS, calcium borosilicate) microcrystalline glass system, uses the Ostwald step rule and nanoscale non-uniform structure as guidance for single crystallization, and promotes single crystallization by regulating the crystallization kinetics of β-CaSiO3. The single crystal β-CaSiO3 with a highly ordered layered structure accelerates the diffusion kinetics of ions and electrons, thereby reducing the dielectric constant of the substrate and improving the mechanical strength, solving the low load problem of existing LTCC materials under the conditions of low dielectric constant and low dielectric loss.

[0040] The glass powder provided by the present invention may include, by mole percentage, 41.68 to 47.2 mol% of CaO (calcium oxide), 12.7 to 15.01 mol% of B2O3 (boron oxide), 37.77 to 40.97 mol% of SiO2 (silicon oxide), and doped modifier ions. The silicon-to-calcium ratio of the glass powder may be 0.9 to 1. The doped modifier ions may include one or more of Al2O3 (aluminum oxide), Ta2O5 (tantalum oxide), Nb2O5 (niobium oxide), La2O3 (lanthanum oxide), CeO2 (cerium oxide), CuO (copper oxide), and BaO (barium oxide). The doped modifier ions can be used to control the properties of β-CaSiO3 single crystal materials. Preferably, the doped modifier ion is Al2O3, and by mole percentage, the glass powder may include 0.34 to 3 mol% of Al2O3.

[0041] Please refer to Figure 1 , Figure 1 A flow chart of a method for preparing glass powder according to some embodiments of the present invention is shown.

[0042] like Figure 1 As shown, the method 100 for preparing glass powder may include step S110: preparing raw materials and fully mixing them, the raw materials including SiO2, H3BO3, CaCO3, and Al(OH)3 weighed in a stoichiometric ratio.

[0043] In a preferred embodiment, the SiO2 included in the glass powder can use national medicine AR (Analytical Reagent) grade silicon oxide as a raw material, the raw material of B2O3 can be electronic grade boric acid, the raw material of CaO can use calcium carbonate as a raw material, and the raw material of Al2O3 can use aluminum hydroxide as a raw material.

[0044] After weighing the raw materials according to the stoichiometric ratio, you can use a mixer to fully mix the raw materials. To make the raw materials more evenly mixed, you can add zirconium beads (i.e., grinding media) to the mixing tank at a 1:1 ball-to-material ratio (the ratio of material to grinding media mass) and mix them for 2 to 3 hours.

[0045] Afterwards, if Figure 1 As shown, the method 100 for preparing glass powder may include step S120: melting the mixed raw materials, and pouring the melted glass liquid into a cooling rolling mill for rapid cooling to obtain a glass sheet.

[0046] In a preferred embodiment, after Al(OH)3 included in the raw materials is introduced into the molten glass, Al (aluminum) ions participate in the glass network and replace some Si (silicon) sites, providing a very favorable environment for the subsequent heat treatment of β-CaSiO3 and its nucleation and growth. Here, the glass melt can form a 95% β-CaSiO3 crystal phase and a 5% residual glass phase. The generated ordered layered structure of β-CaSiO3 can provide good kinetics for ion and electron polarization, thereby providing a favorable environment for the formation of a low dielectric constant. At the same time, β-CaSiO3 is transformed into a single crystal structure, so the mechanical properties are also greatly improved.

[0047] In a preferred embodiment, the mixed raw materials can be melted at 1350-1450°C for 1-3 hours. Specifically, to prevent contamination from other elements, a platinum crucible can be used during the melting process. Furthermore, to prevent excessive volatilization of boron, a batch-feeding process using pressed cakes can be employed. The melted glass is then poured into a cooling mill for rapid cooling, thereby rapidly cooling the glass into glass sheets. The cooling mill can be a double-roll cooling mill.

[0048] Please continue to refer to Figure 1 The glass powder preparation method 100 may include step S130: placing a glass sheet in a grinder for preliminary crushing to obtain glass particles. In one embodiment, the glass sheet may be initially crushed into glass particles having a particle size range of approximately 0.5 to 2.0 mm using a three-drum grinder. Here, the glass particles are calcium borosilicate (CBS) glass particles.

[0049] The glass powder preparation method 100 may further include step S140: the glass particles are subjected to a jet mill and an airflow classifier to obtain glass powder within a predetermined particle size distribution range. The predetermined particle size distribution range of the glass powder may be 3.0 to 4.0 μm. In terms of molar percentage, the glass powder may include 41.68 to 47.2 mol% of CaO, 12.7 to 15.01 mol% of B2O3, 37.77 to 40.97 mol% of SiO2, and doped modifier ions. The silicon-to-calcium ratio of the glass powder may be 0.9 to 1.

[0050] When the raw materials are SiO2, H3BO3, CaCO3, and Al(OH)3, the glass powder may include 41.68 to 47.2 mol% of CaO, 12.7 to 15.01 mol% of B2O3, 37.77 to 40.97 mol% of SiO2, and 0.34 to 3 mol% of Al2O3.

[0051] Those skilled in the art will understand that the above-mentioned steps for preparing the glass powder are only a non-limiting embodiment provided by the present invention, which is intended to clearly illustrate the main concept of the present invention and provide a specific solution that is convenient for the public to implement, rather than to limit the scope of protection of the present invention. In other embodiments, those skilled in the art may also adopt other equivalent methods based on the concept of the present invention to obtain a glass powder having a formula of 41.68-47.2 mol% CaO, 12.7-15.01 mol% B2O3, 37.77-40.97 mol% SiO2, and 0.34-3 mol% Al2O3.

[0052] After obtaining glass powder, single crystal glass ceramics can be prepared. Please refer to Figure 2 , Figure 2 A flow chart of a method for preparing single crystal glass ceramics according to some embodiments of the present invention is shown.

[0053] like Figure 2 As shown, the preparation method 200 of single crystal glass ceramics may include step S210: mixing glass powder with an organic solvent, casting to obtain a green ceramic tape, laminating and pressing the green ceramic tape, and then placing the green ceramic tape in a sintering furnace for sintering.

[0054] Specifically, the glass powder is first mixed with an organic solvent. The glass powder is placed in a zirconium tank, PVB resin is used as a binder, one or more of butanone, butyl acetate, cyclohexane, cyclohexanone, terpineol, methyl ethyl ketone, toluene, and xylene are used as organic solvents, and a certain amount of dispersant is added and mixed for 4 to 6 hours to prepare the casting slurry. Here, the organic solvent can be used in combination according to the volatilization temperature. After that, a uniform and smooth green porcelain tape can be prepared by casting. The prepared casting slurry is heated to a certain viscosity and cast by a casting machine to obtain a green porcelain tape of a certain thickness. After the green porcelain tape has been processed by lamination, pressing, etc., it can be placed in a sintering furnace for sintering.

[0055] like Figure 2As shown, the preparation method 200 of single-crystal glass ceramics may include a sintering process, which may include steps S220, S230, and S240: heating to 500-550°C at a rate of 1-2°C / min, holding for 4-5 hours, and then performing binder removal; then heating to 860-880°C at a rate of 3-5°C / min, holding for 10-30 minutes; and cooling to obtain single-crystal glass ceramics. The obtained single-crystal glass ceramics can be co-fired with silver paste without silver diffusion. Preferably, the sintering shrinkage of the single-crystal glass ceramics is 15-18% to ensure shrinkage matching, stress matching, and co-firing matching at the interface between the silver and the LTCC substrate.

[0056] The following are several preferred embodiments, based on which the glass powder and its preparation method proposed in the present invention, as well as the single crystal glass ceramics obtained based on the glass powder and its preparation method are described in detail.

[0057] Please refer to Figure 3 , Figure 3 The formulas of glass powders provided according to multiple embodiments of the present invention and multiple comparative examples are shown.

[0058] In the preparation process of the glass powder provided in Example 1, the raw materials can first be prepared according to the stoichiometric ratio requirements. The SiO2 included in the glass powder can be made from AR-grade silicon oxide, the B2O3 can be made from electronic-grade boric acid, the CaO can be made from calcium carbonate, and the Al2O3 can be made from aluminum hydroxide. The raw materials are then thoroughly mixed using a mixer, and zirconium beads can be added to the mixing tank at a 1:1 ball-to-batch ratio. The mixing time is 2-3 hours.

[0059] A platinum crucible is used to melt the raw materials, and a cake-pressed batch feeding process is adopted to prevent excessive volatilization of the boron element. The melting temperature is 1450°C, and the melting time is 1 to 3 hours. Afterwards, the molten glass liquid is poured into a double-roll cooling mill for rapid cooling, thereby rapidly cooling the glass liquid into glass sheets. The glass sheets are then initially crushed into glass particles of about 0.5 to 2.0 mm using a three-drum grinder, and the glass particles are then passed through an air flow mill in combination with an air flow classifier to obtain 3 to 4 μm glass powder. Figure 3 As shown, the glass powder A1 provided in Example 1 may include 41.68 mol% of CaO, 15.01 mol% of B2O3, 40.97 mol% of SiO2 and 2.34 mol% of Al2O3, and the silicon-calcium ratio is 0.98.

[0060] Afterwards, the glass powder provided in Example 1 is mixed with an organic solvent and cast to obtain a green porcelain tape. The green porcelain tape is then stacked and pressed and then placed in a sintering furnace for sintering.

[0061] Specifically, the glass powder is loaded into a zirconium tank, PVB resin is used as a binder, one or more of butanone, butyl acetate, cyclohexane, cyclohexanone, terpineol, methyl ethyl ketone, toluene, and xylene are used as organic solvents, and a certain amount of dispersant is added and mixed for 4 to 6 hours to prepare the casting slurry. Here, the organic solvent can be used in combination according to the volatilization temperature. Afterwards, the prepared casting slurry is heated to a certain viscosity and cast through a casting machine to obtain a green porcelain tape of a certain thickness. After the green porcelain tape has been processed by lamination, pressing, etc., it can be placed in a sintering furnace for sintering to obtain single crystal glass ceramics. In Example 1, the sintering process can be heated to 500°C at a rate of 2°C / min, kept warm for 4 hours, and then the binder is removed. Then the temperature is raised to 880°C at a rate of 5°C / min, kept warm for 30 minutes, and cooled to obtain single crystal glass ceramics.

[0062] Please refer to Figure 4 and Figure 5 , Figure 4 The performance test results of glass ceramics provided by multiple embodiments and multiple comparative examples according to the present invention are shown. Figure 5 The figures show the bending strength of glass ceramics provided according to various embodiments of the present invention and various comparative examples.

[0063] like Figure 4 、 Figure 5 As shown, the single crystal glass ceramic prepared based on the glass powder provided in Example 1 has a dielectric constant k of 4.01 and a dielectric loss of 0.00317 at 10 MHz; a dielectric constant k of 4.04 and a dielectric loss of 0.00315 at 15 GHz; and a flexural strength of 256 MPa. This shows that the single crystal glass ceramic provided by the present invention has a low sintering temperature (880°C), a small dielectric constant (4.04@15 GHz) and dielectric loss (0.00315@15 GHz), and a high mechanical strength (256 MPa).

[0064] In the preparation process of the glass powder provided in Example 2, the raw materials can first be prepared according to the stoichiometric ratio requirements. The SiO2 included in the glass powder can be made from AR-grade silicon oxide, the B2O3 can be made from electronic-grade boric acid, the CaO can be made from calcium carbonate, and the Al2O3 can be made from aluminum hydroxide. Afterwards, the raw materials are thoroughly mixed using a mixer, and zirconium beads can be added to the mixing tank at a 1:1 ball-to-batch ratio. The mixing time is 2-3 hours.

[0065] A platinum crucible is used to melt the raw materials, and a cake-pressed batch feeding process is adopted to prevent excessive volatilization of the boron element. The melting temperature is 1450°C, and the melting time is 1 to 3 hours. Afterwards, the molten glass liquid is poured into a double-roll cooling mill for rapid cooling, thereby rapidly cooling the glass liquid into glass sheets. The glass sheets are then initially crushed into glass particles of about 0.5 to 2.0 mm using a three-drum grinder, and the glass particles are then passed through an air flow mill in combination with an air flow classifier to obtain 3 to 4 μm glass powder. Figure 3 As shown, the glass powder A2 provided in Example 2 may include 42.04 mol% of CaO, 15.14 mol% of B2O3, 41.32 mol% of SiO2 and 1.5 mol% of Al2O3, and the silicon-calcium ratio is 0.98.

[0066] Afterwards, the glass powder provided in Example 2 is placed in a zirconium can, PVB resin is used as a binder, one or more of butanone, butyl acetate, cyclohexane, cyclohexanone, terpineol, methyl ethyl ketone, toluene, and xylene are used as organic solvents, and a certain amount of dispersant is added and mixed for 4 to 6 hours to prepare the casting slurry. Here, the organic solvent can be used in combination according to the volatilization temperature. Afterwards, the prepared casting slurry is heated to a certain viscosity and cast through a casting machine to obtain a green porcelain tape of a certain thickness. After the green porcelain tape has been processed by lamination, pressing, etc., it can be placed in a sintering furnace for sintering to obtain single crystal glass ceramics. In Example 2, the sintering process can be heated to 500°C at a rate of 2°C / min, kept warm for 4 hours, and then the binder is removed, and then the temperature is raised to 880°C at a rate of 5°C / min, kept warm for 30 minutes, and cooled to obtain single crystal glass ceramics.

[0067] like Figure 4 、 Figure 5 As shown, the single crystal glass ceramic provided in Example 2 has a dielectric constant k of 4.10 and a dielectric loss of 0.00386 at 10 MHz; a dielectric constant k of 4.12 and a dielectric loss of 0.00386 at 15 GHz; and a flexural strength of 237 MPa.

[0068] In addition, please refer to Figure 6 and Figure 7 , Figure 6 The figure shows the ex-situ selected area electron diffraction pattern of the glass powder provided in Example 2 according to the present invention after being sintered at 880° C. and kept warm for 30 minutes. Figure 7 The microscopic morphology of the glass powder provided in Example 2 of the present invention after sintering at 880° C. and keeping warm for 30 minutes is shown.

[0069] like Figure 6As shown, the glass powder provided in Example 2 formed a regular diffraction spot sample after sintering at 880°C and holding for 30 minutes. This sample exhibited single crystal properties, consistent with the crystal system of β-CaSiO3. Furthermore, the arrangement pattern indicated that the sample was monoclinic. Therefore, it can be determined that the β-CaSiO3 in the sample formed single crystals during the sintering process.

[0070] like Figure 7 As shown, the sample formed after sintering the glass powder provided in Example 2 at 880°C and holding at this temperature for 30 minutes exhibits dense, non-porous characteristics. The bright field area (lighter color area) is a single-crystalline β-CaSiO3 crystal phase, while the dark field area (darker color area) is a residual glass phase. The single-crystalline β-CaSiO3 crystal phase content is high, and the residual glass phase content is very low. Dense single-crystalline glass ceramics can significantly reduce the dielectric loss of LTCC materials.

[0071] pass Figure 6 and Figure 7 It can be explained that when the glass powder provided in Example 2 is used to prepare single-crystal glass ceramics, its crystal phase only precipitates β-CaSiO3 phase, and the precipitated crystal phase can be converted into single-crystal β-CaSiO3 at a lower sintering temperature, thereby improving the mechanical strength of the LTCC material and achieving a low dielectric constant.

[0072] The following are a number of comparative examples compared with the above-mentioned embodiments, based on which the performance effects of the glass powder proposed in the present invention and the single crystal glass ceramics obtained based on the glass powder are further explained.

[0073] In the preparation process of the glass powder provided in Comparative Example 1, the raw materials can first be prepared according to the stoichiometric ratio requirements. The SiO2 included in the glass powder can be made from AR-grade silicon oxide, the B2O3 can be made from electronic-grade boric acid, the CaO can be made from calcium carbonate, and the Al2O3 can be made from aluminum hydroxide. The raw materials are then thoroughly mixed using a mixer, and zirconium beads can be added to the mixing tank at a 1:1 ball-to-batch ratio. The mixing time is 2-3 hours.

[0074] A platinum crucible is used to melt the raw materials, and a cake-pressed batch feeding process is adopted to prevent excessive volatilization of the boron element. The melting temperature is 1450°C, and the melting time is 1 to 3 hours. Afterwards, the molten glass liquid is poured into a double-roll cooling mill for rapid cooling, thereby rapidly cooling the glass liquid into glass sheets. The glass sheets are then initially crushed into glass particles of about 0.5 to 2.0 mm using a three-drum grinder, and the glass particles are then passed through an air flow mill in combination with an air flow classifier to obtain 3 to 4 μm glass powder. Figure 3As shown, the glass powder A3 provided in Comparative Example 1 may include 42.53 mol% of CaO, 15.32 mol% of B2O3, 41.81 mol% of SiO2 and 0.34 mol% of Al2O3, and the silicon-calcium ratio is 0.98.

[0075] Afterwards, the glass powder provided in Comparative Example 1 is placed in a zirconium can, PVB resin is used as a binder, one or more of butanone, butyl acetate, cyclohexane, cyclohexanone, pinene alcohol, methyl ethyl ketone, toluene, and xylene are used as organic solvents, and a certain amount of dispersant is added and mixed for 4 to 6 hours to prepare the casting slurry. Here, the organic solvent can be used in combination according to the volatilization temperature. Afterwards, the prepared casting slurry is heated to a certain viscosity and cast by a casting machine to obtain a green porcelain tape of a certain thickness. After the green porcelain tape has been processed by lamination, pressing, etc., it can be placed in a sintering furnace for sintering to obtain glass ceramics. In Comparative Example 1, the sintering process can be heated to 500°C at a rate of 2°C / min, kept warm for 4 hours, and then the binder is removed. Then the temperature is raised to 850°C at a rate of 5°C / min, kept warm for 30 minutes, and cooled to obtain glass ceramics.

[0076] like Figure 4 、 Figure 5 As shown, the single-crystal glass-ceramic provided in Comparative Example 1 has a dielectric constant k of 4.23 and a dielectric loss of 0.00379 at 10 MHz; a dielectric constant k of 4.30 and a dielectric loss of 0.00391 at 15 GHz; and a flexural strength of 181 MPa. Compared to a sintering temperature of 880°C, a sintering temperature of 850°C does not effectively promote the conversion of single-crystal β-CaSiO3. Therefore, the flexural strength of the glass-ceramic provided in Comparative Example 1 is significantly lower than that of Examples 1 and 2, but is higher than that of other existing LTCC materials.

[0077] In the preparation process of the glass powder provided in Comparative Example 2, the raw materials can first be prepared according to the stoichiometric ratio requirements. The SiO2 included in the glass powder can be made from AR-grade silicon oxide, the B2O3 can be made from electronic-grade boric acid, the CaO can be made from calcium carbonate, and the Al2O3 can be made from aluminum hydroxide. The raw materials are then thoroughly mixed using a mixer, and zirconium beads can be added to the mixing tank at a 1:1 ball-to-batch ratio. The mixing time is 2-3 hours.

[0078] A platinum crucible is used to melt the raw materials, and a cake-pressed batch feeding process is adopted to prevent excessive volatilization of the boron element. The melting temperature is 1450°C, and the melting time is 1 to 3 hours. Afterwards, the molten glass liquid is poured into a double-roll cooling mill for rapid cooling, thereby rapidly cooling the glass liquid into glass sheets. The glass sheets are then initially crushed into glass particles of about 0.5 to 2.0 mm using a three-drum grinder, and the glass particles are then passed through an air flow mill in combination with an air flow classifier to obtain 3 to 4 μm glass powder. Figure 3 As shown, the glass powder A4 provided in Comparative Example 2 may include 47.2 mol% of CaO, 12.7 mol% of B2O3, 37.76 mol% of SiO2 and 2.34 mol% of Al2O3, and the silicon-calcium ratio is 0.80.

[0079] Afterwards, the glass powder provided in Comparative Example 2 is placed in a zirconium can, PVB resin is used as a binder, one or more of butanone, butyl acetate, cyclohexane, cyclohexanone, pineol, methyl ethyl ketone, toluene, and xylene are used as organic solvents, and a certain amount of dispersant is added and mixed for 4 to 6 hours to prepare the casting slurry. Here, the organic solvent can be used in combination according to the high or low volatilization temperature. Afterwards, the prepared casting slurry is heated to a certain viscosity and cast by a casting machine to obtain a green porcelain tape of a certain thickness. After the green porcelain tape has been processed by lamination, pressing, etc., it can be placed in a sintering furnace for sintering to obtain glass ceramics. In Comparative Example 2, the sintering process can be heated to 500°C at a rate of 2°C / min, kept warm for 4 hours, and then the binder is removed. Then the temperature is raised to 850°C at a rate of 5°C / min, kept warm for 30 minutes, and cooled to obtain glass ceramics.

[0080] like Figure 4 、 Figure 5 As shown, the glass ceramic provided in Comparative Example 2 has a dielectric constant k of 4.31 and a dielectric loss of 0.00257 at 10 MHz; a dielectric constant k of 4.36 and a dielectric loss of 0.00234 at 15 GHz; and a flexural strength of 160 MPa.

[0081] Please refer to Figure 8 , Figure 8 A comparison of the XRD patterns of the single crystal glass ceramics provided in Example 1 and Comparative Example 2 of the present invention is shown.

[0082] like Figure 8As shown, the crystal type of the single crystal glass ceramics provided in Example 1 and Comparative Example 2 can be determined based on the intensity of the diffraction peaks through the XRD (X-Ray Diffraction) spectrum. Line 801 is the result of the XRD spectrum of the single crystal glass ceramics provided in Example 1, and line 802 is the result of the XRD spectrum of the single crystal glass ceramics provided in Comparative Example 2. The difference between the glass powder formulas of Example 1 and Comparative Example 2 is the silicon-calcium ratio (Si / Ca). The silicon-calcium ratio of Example 1 is 0.98, and the silicon-calcium ratio of Comparative Example 2 is 0.80. Figure 8 It can be seen that the diffraction peak intensity of line 801 is greater than that of line 802, indicating that a high silicon-calcium ratio (i.e., Example 1) is more conducive to the precipitation of high-strength β-CaSiO3. Therefore, the flexural strength of Example 1 is better than that of Comparative Example 2.

[0083] The preparation method of the glass powder and glass ceramic provided in Comparative Example 3 is the same as that in Example 1. Figure 3 As shown, the difference between Comparative Example 3 and Example 1 is that the glass powder formula provided in Comparative Example 3 contains 0 mol% Al2O3. Therefore, during the preparation of the glass powder provided in Comparative Example 3, the raw materials prepared do not include aluminum hydroxide. Specifically, the glass powder A5 provided in Comparative Example 3 includes 42.68 mol% CaO, 15.37 mol% B2O3, and 41.95 mol% SiO2, with a silicon-calcium ratio of 0.98.

[0084] like Figure 4 、 Figure 5 As shown, the glass-ceramic provided in Comparative Example 3 has a dielectric constant k of 5.54 and a dielectric loss of 0.002 at 10 MHz; a dielectric constant k of 5.61 and a dielectric loss of 0.0018 at 15 GHz; and a flexural strength of 156 MPa. This indicates that without the introduction of modifier ions (such as Al2O3), it is impossible to promote the single crystallization of β-CaSiO3, and therefore it is impossible to improve the mechanical strength and dielectric properties of the LTCC material.

[0085] The preparation method of the glass powder and glass ceramic provided in Comparative Example 4 is the same as that in Example 1. Figure 3 As shown, the difference between Comparative Example 4 and Example 1 is that the Al2O3 content in the glass powder formula provided in Comparative Example 4 is higher than that in Example 1, and the Al2O3 content in Comparative Example 4 is 5.34 mol%. Specifically, the glass powder A6 provided in Comparative Example 4 includes 40.4 mol% CaO, 14.55 mol% B2O3, 39.71 mol% SiO2, and 5.34 mol% Al2O3, with a silicon-to-calcium ratio of 0.98.

[0086] like Figure 4 、 Figure 5 As shown, the glass-ceramic provided in Comparative Example 4 has a dielectric constant k of 4.87 and a dielectric loss of 0.00321 at 10 MHz; a dielectric constant k of 4.93 and a dielectric loss of 0.00473 at 15 GHz; and a flexural strength of 81 MPa. This indicates that when the content of introduced modifier ions (such as Al2O3) is too high, the glass liquid phase is excessive and the crystalline phase content is reduced, resulting in a sharp decrease in the flexural strength of the glass-ceramic.

[0087] Furthermore, the preparation method of the glass powder and glass ceramic provided in Comparative Example 5 is the same as that in Example 1, as shown in FIG. Figure 3 As shown, the difference between Comparative Example 5 and Example 1 is that the Al2O3 content in Comparative Example 5 is higher than that in Example 1, and the silicon-calcium ratio is lower than that in Example 1. Specifically, the glass powder A7 provided in Comparative Example 5 includes 46.8 mol% CaO, 10.41 mol% B2O3, 37.45 mol% SiO2, and 5.34 mol% Al2O3, and the silicon-calcium ratio is 0.80.

[0088] like Figure 4 、 Figure 5 As shown, the glass-ceramic provided in Comparative Example 5 has a dielectric constant k of 5.24 and a dielectric loss of 0.00322 at 10 MHz; at 15 GHz, the dielectric constant k is 5.29 and the dielectric loss is 0.00312; and the flexural strength is 75 MPa. This indicates that when the content of introduced modifier ions (such as Al2O3) is too high and the silicon-calcium ratio is reduced, the flexural strength of the glass-ceramic decreases sharply and the dielectric constant of the LTCC material increases, failing to meet the low dielectric constant requirement.

[0089] The preparation method of the glass powder and glass ceramic provided in Comparative Example 6 is the same as that in Example 2. Figure 3 As shown, the difference between Comparative Example 6 and Example 2 is that the silicon-calcium ratio of the glass powder provided in Comparative Example 6 is lower than that in Example 2. The silicon-calcium ratio in Example 2 is 0.98, while the silicon-calcium ratio in Comparative Example 6 is 0.80. Specifically, the glass powder A8 provided in Comparative Example 6 includes 46.51 mol% CaO, 14.78 mol% B2O3, 37.21 mol% SiO2, and 1.5 mol% Al2O3.

[0090] like Figure 4 、 Figure 5As shown, the glass-ceramic provided in Comparative Example 6 has a dielectric constant k of 5.46 and a dielectric loss of 0.00248 at 10 MHz; a dielectric constant k of 5.47 and a dielectric loss of 0.00217 at 15 GHz; and a flexural strength of 176 MPa. This indicates that a reduction in the silicon-calcium ratio, i.e., an excessively low silicon content, reduces the amount of precipitated calcium silicate. Furthermore, the presence of small amounts of high-dielectric-constant, high-sintering-temperature impurity phases (such as α-CaSiO3 and Ca2O4) can result in an excessively high dielectric constant of the LTCC material, degrading the dielectric properties of the LTCC substrate and reducing the mechanical strength of the LTCC material.

[0091] In addition, the preparation method of the glass powder and glass ceramic provided in Comparative Example 7 is the same as that in Comparative Example 1. Figure 3 As shown, the difference between Comparative Example 7 and Comparative Example 1 is that the glass powder formula provided in Comparative Example 7 increases the B2O3 content and reduces the silicon content. That is, compared with Comparative Example 1, the silicon-calcium ratio in Comparative Example 7 is lower. The silicon-calcium ratio in Comparative Example 1 is 0.98, while the silicon-calcium ratio in Comparative Example 7 is 0.80. Specifically, the glass powder A9 provided in Comparative Example 7 includes 45.95 mol% CaO, 16.94 mol% B2O3, 36.77 mol% SiO2, and 0.34 mol% Al2O3.

[0092] like Figure 4 、 Figure 5 As shown, the glass-ceramic provided in Comparative Example 7 has a dielectric constant k of 5.32 and a dielectric loss of 0.00364 at 10 MHz; at 15 GHz, the dielectric constant k is 5.38 and the dielectric loss is 0.00425; and the flexural strength is 164 MPa. This indicates that a reduction in the silicon-calcium ratio, i.e., an excessively low silicon content, can lead to an excessively high dielectric constant of the LTCC material, degrading the dielectric properties of the LTCC substrate and reducing the mechanical strength of the LTCC material.

[0093] In summary, the single-crystal glass ceramics provided by the present invention do not contain any externally doped ceramic powder, have a low sintering temperature, a small dielectric constant and dielectric loss, and a high mechanical strength. They can balance and improve the sintering temperature, dielectric constant, dielectric loss, and bending strength of the LTCC substrate, and are therefore widely used in modern 5G / 6G electronic communications fields such as mobile communications, high-frequency electronics, wireless local area networks, satellite communications, and aerospace electronics.

[0094] Although the above methods are illustrated and described as a series of acts for simplicity of explanation, it is to be understood and appreciated that these methods are not limited by the order of the acts, as some acts may occur in a different order and / or concurrently with other acts from those illustrated and described herein or not illustrated and described herein but understandable to those skilled in the art according to one or more embodiments.

[0095] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing single crystal glass ceramics, characterized in that: Including steps: A glass powder is mixed with an organic solvent, and the mixture is cast to obtain a green porcelain tape. The green porcelain tape is laminated and pressed, and then placed in a sintering furnace for sintering. The glass powder comprises, by mole percentage, 41.68 to 47.2 mol% of CaO, 12.7 to 15.01 mol% of B2O3, 37.77 to 40.97 mol% of SiO2, and doped modifier ions, wherein the modifier ions include Al2O3, the glass powder comprises 0.34 to 3 mol% of the Al2O3, and the silicon-calcium ratio of the glass powder is 0.9 to 1. The sintering process includes: Raise the temperature to 500-550°C at a rate of 1-2°C / min, keep warm for 4-5 hours and then perform binder removal; Raise the temperature to 860-880°C at a rate of 3-5°C / min and keep at this temperature for 10-30 minutes; and After cooling, single crystal glass ceramics are obtained.

2. The method for preparing a single crystal glass ceramic according to claim 1, wherein: The sintering shrinkage of the glass powder is 15% to 18%.

3. The method for preparing a single crystal glass ceramic according to claim 1, wherein: The preparation of the glass powder comprises the following steps: Prepare raw materials and mix them thoroughly, wherein the raw materials include SiO2, H3BO3, CaCO3, and Al(OH)3 weighed in a stoichiometric ratio; Melting the mixed raw materials and pouring the melted glass into a cooling mill for rapid cooling to obtain glass sheets; placing the glass sheets into a grinder for preliminary crushing to obtain glass particles; and The glass particles are jet milled and processed with an air flow classifier to obtain glass powder within a preset particle size distribution range.

4. The method for preparing a single crystal glass ceramic according to claim 3, wherein: The step of melting the mixed raw materials comprises: The prepared raw materials are melted at 1350-1450° C. for 1-3 hours.

5. The method for preparing single crystal glass ceramics according to claim 3, wherein: The particle size of the glass particles ranges from 0.5 to 2.0 mm.

6. The method for preparing a single crystal glass ceramic according to claim 3, wherein: The preset particle size distribution range of the glass powder is 3.0 to 4.0 μm.

7. A single crystal glass ceramic, characterized in that: The single crystal glass ceramic is produced by the method for producing the single crystal glass ceramic according to any one of claims 1 to 6.

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