A low dielectric constant and high thermal conductivity LTCC material and its preparation method

Abstract

This invention discloses a low dielectric constant and high thermal conductivity LTCC material and its preparation method. Through ceramic / glass multiphase design and compositional control, this invention achieves densification at temperatures below 900℃. Zinc aluminate and boron nitride are used as ceramic fillers. The layered crystal structure of boron nitride, under uniform dispersion, imparts anisotropic thermal conductivity to the material, creating an efficient thermal pathway. Its low dielectric constant further optimizes high-frequency signal transmission performance. Simultaneously, this structure, through its high modulus and the effect of inhibiting crack propagation after dispersion, imparts a fiber-like mechanical strengthening effect to the ceramic, distinct from traditional fiber reinforcement mechanisms. However, excessive boron nitride in the ceramic can lead to the formation of porous structures that are difficult to sinter densely.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, specifically to a low dielectric constant and high thermal conductivity LTCC material and its preparation method. Background Technology

[0002] With the rapid iteration of mobile communication technology, humanity has gradually entered the fifth-generation mobile communication (5G) era. To alleviate the shortage of frequency band resources, communication frequencies are expanding from traditional microwave bands to millimeter waves and even terahertz high-frequency bands. Against this backdrop, low-temperature co-firing ceramics (LTCC) materials with low dielectric constant (εᵣ) and low dielectric loss (tanδ) have become a research hotspot. These materials, with their excellent high-frequency signal transmission performance and three-dimensional integration capabilities, can significantly reduce signal attenuation in 5G devices at high frequencies. In addition, the power consumption of 5G base stations is 2.5 to 4 times that of 4G. The miniaturization of devices and high-frequency chips lead to a surge in heat dissipation pressure. This requires LTCC materials to possess both low dielectric loss (tanδ<0.002) and high thermal conductivity to balance high-frequency signal and heat dissipation requirements, ensuring long-term stable operation of devices at -55°C to 125°C.

[0003] Currently, low-dielectric LTCC materials are mainly divided into three categories: glass-type, glass / ceramic composite, and single-phase ceramic. The coefficient of thermal expansion (CTE) of glass-type LTCC materials is often difficult to perfectly match with semiconductor chips (such as Si and GaAs), and the manufacturing process is more complex, requiring precise control of the ratio of crystalline and glass phases to ensure performance stability. Single-phase ceramic LTCC materials typically have a narrow dielectric constant (εᵣ) range, making it difficult to simultaneously meet the requirements of high-frequency low εᵣ (such as 5G antennas) and high εᵣ (such as integrated capacitors), limiting design flexibility, and exhibiting high brittleness and ceramic hardness. Based on current LTCC technology development trends and application needs, glass / ceramic composite LTCC material systems are attracting widespread attention in the field of electronic packaging technology due to their excellent designability and commercial potential. This material uses a glass phase and ceramic bulk as raw materials, and by precisely controlling the ratio of the two phases and the characteristics of the crystalline phase, it is possible to achieve directional design of key parameters such as dielectric properties and coefficient of thermal expansion. This combination of adjustable performance and economical manufacturing processes makes it a cutting-edge material solution for addressing the development needs of high-frequency, high-speed, and high-density integrated electronic devices.

[0004] Zinc aluminate is a potential microelectronic material due to its low dielectric constant, low loss, high thermal conductivity, and corrosion resistance. However, the sintering temperature of traditional zinc aluminate is usually above 1400℃, making it difficult to be compatible with low-melting-point electrode materials (such as Ag and Cu), and its high energy consumption limits its application in the field of low-temperature co-firing (LTCC). Therefore, developing an LTCC material system that can significantly reduce the sintering temperature of zinc aluminate while maintaining excellent microwave dielectric properties is of great significance. To achieve low-temperature co-firing, Tianying Qin et al. reported in their article "Low-temperature sintering mechanism and microwave dielectric properties of ZnAl2O4-LMZBS composites" published in the Journal of Alloys and Compounds, 2019, Vol. 797, pp. 744-753, that by adding LMZBS glass additive, the material achieved optimal microwave dielectric properties after sintering at 930℃ for 3 h: εr = 7.4, tanδ = 0.0002, and flexural strength = 141 MPa. However, the τ of this material... f The value is relatively high, at 43.99 ppm / ℃. Zhang Ping et al., in their article "The Influence of Adding ZnO-B2O3-SiO2 Glass on the Sintering and Microwave Dielectric Properties of 0.79ZnAl2O4-0.21TiO2 Ceramics," published in *Chinese Ceramics*, Vol. 49, No. 9, 2013, reported that by adding an appropriate amount of zinc borosilicate glass, the sintering temperature of zinc aluminate ceramics could be reduced to 950 ℃, and better microwave dielectric properties were obtained: εr = 11.2, tanδ = 0.0005, and τ... f The dielectric constant is 26 ppm / ℃, but the sintering temperature is still relatively high. Chinese invention patent CN109650871A reports a potassium aluminum borosilicate glass / zinc borosilicate glass / alumina LTCC material that can be sintered at 810℃~850℃, producing zinc aluminate through reactive crystallization. Its dielectric constant is 4~4.65, tanδ is 0.003~0.004, thermal expansion coefficient is 4.7~5.6 ppm / ℃, and flexural strength is 150~202 MPa. Korean invention patent KR 20100137665A reports a calcium aluminum borosilicate glass / alumina LTCC material that produces zinc aluminate through reactive crystallization and is sintered at 850℃~950 °C. The resulting material has a dielectric constant range of 3.4~5.5 and tanδ of 0.002~0.004 GHz.

[0005] In summary, while existing research has significantly reduced the sintering temperature of zinc aluminate ceramics (to 850–950 °C) by adding glass additives (such as LMZBS and zinc borosilicate glass), it still faces challenges such as insufficient dielectric properties (e.g., τf or tanδ) or excessively high sintering temperatures. Although zinc aluminate systems generated through reaction crystallization achieve even lower sintering temperatures (810–850 °C), their dielectric losses (tanδ) are generally higher than 0.002, making it difficult to meet the requirements of high-frequency, high-thermal-conductivity applications. Therefore, developing a zinc aluminate-based material that combines low-temperature sintering (<900 °C), low dielectric constant, low dielectric loss (tanδ<0.002), and high thermal conductivity is crucial for promoting the application of LTCC technology in 5G / 6G microelectronic packaging. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a low dielectric constant and high thermal conductivity LTCC material and its preparation method.

[0007] In a first aspect, the present invention provides a low dielectric constant and high thermal conductivity LTCC material, comprising the following components by weight percentage: 20%~48% zinc borosilicate glass, 6%~26% magnesium aluminum borosilicate glass, 2%~10% boron nitride, 30%~60% zinc aluminate, and 4%~10% titanium dioxide, wherein the sum of zinc borosilicate glass, magnesium aluminum borosilicate glass, boron nitride, zinc aluminate, and titanium dioxide is 100%; wherein the mass ratio of the total amount of zinc borosilicate glass and magnesium aluminum borosilicate glass to zinc aluminate is 1-2:1; and the mass ratio of zinc borosilicate glass to magnesium aluminum borosilicate glass is 1.5-5:1.

[0008] Preferably, the zinc borosilicate glass comprises the following raw materials by weight percentage: 30%~70% ZnO, 10%~60% B2O3, 5%~30% SiO2, 1%~3% Bi2O3, 1%~5% R2O, and 1%~5% MO, wherein: R2O is at least one of Li2O and K2O; and MO is one or more of CuO, CaO, and MnO2.

[0009] Preferably, the magnesium aluminum borosilicate glass composition includes 10%~20% MgO, 10%~20% Al2O3, 12%~25% B2O3, 45%~65% SiO2, and 1%~3% R2O and 1%~2% MsO, wherein: R2O is at least one of Li2O, K2O, and Na2O; and MsO is one or more of CuO, CaO, MnO2, ZnO, and Na2O.

[0010] Secondly, the present invention provides a method for preparing a low dielectric constant and high thermal conductivity LTCC material, the method comprising the following:

[0011] Zinc borosilicate glass, magnesium aluminum borosilicate glass, boron nitride, zinc aluminate, and titanium dioxide were ball-milled and then dried using ethanol as a solvent to obtain low-temperature co-fired ceramic powder.

[0012] The obtained low-temperature co-fired ceramic powder was added to a PVA solution, ground and granulated, then sieved and pressed into a green body.

[0013] The green body is sintered at high temperature to obtain LTCC material with low dielectric constant, low dielectric loss and high thermal conductivity.

[0014] Preferably, the spheroidization time during the preparation of the low-temperature co-fired ceramic powder is 16h~24h.

[0015] Preferably, the PVA solution has a weight content of 5% to 8% of the low-temperature co-fired ceramic powder.

[0016] Preferably, the high-temperature sintering conditions for the green body are as follows: heating from room temperature to 400-500°C at a rate of 0.5-2°C / min and holding at that temperature for 1-2 hours, then heating to 870-900°C at a rate of 3-10°C / min and holding at that temperature for 30-60 minutes.

[0017] Preferably, the preparation of the zinc borosilicate glass includes:

[0018] After ZnO, B2O3, SiO2, Bi2O3, R2O and MO are mixed evenly, they are melted at high temperature of 1300℃~1400℃ for 1~2 hours to obtain transparent glass melt.

[0019] The molten glass is quenched in deionized water to obtain transparent glass shards.

[0020] After crushing the glass shards, they are placed in a ball mill jar, and the mixture is ball-milled and dried using anhydrous ethanol as the medium to obtain glass powder.

[0021] Preferably, the preparation of the magnesium aluminum borosilicate glass includes:

[0022] Combine MgO, Al2O3, B2O3, SiO2, R2O, M S After the O is mixed evenly, it is melted at high temperature of 1450℃~1550℃ for 1~2 hours to obtain transparent glass liquid;

[0023] The molten glass is quenched in deionized water to obtain transparent glass shards.

[0024] The broken glass shards are crushed, placed in a ball mill jar, and milled and dried using anhydrous ethanol as the medium to obtain glass powder.

[0025] Preferably, the mass ratio of glass slag, anhydrous ethanol, and grinding balls in the preparation process of the zinc borosilicate glass and magnesium aluminum borosilicate glass is 1:1:5. Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The low dielectric constant and high thermal conductivity LTCC material prepared in this invention uses zinc aluminate and boron nitride as ceramic fillers. The spinel structure of zinc aluminate has both high thermal conductivity (~25 W / mK) and suitable dielectric constant (~8.5), providing intrinsic low loss characteristics for the matrix. However, the pure phase requires high-temperature sintering (>1400℃), so an appropriate amount of glass phase is needed to assist in cooling. The layered crystal structure of boron nitride, under the premise of uniform dispersion, endows the material with anisotropic thermal conductivity (~300 W / mK in-plane), constructing an efficient thermal path for the material. Its low dielectric constant (~4) can further optimize the high-frequency signal transmission performance. At the same time, this structure can also endow the ceramic with a fiber-like mechanical strengthening effect that is different from the traditional fiber reinforcement mechanism through its own high modulus characteristics and the effect of inhibiting crack propagation after dispersion. However, too much boron nitride ceramic will form pores that are difficult to sinter densely.

[0027] (2) The glass used in this invention is a mixture of zinc borosilicate glass and magnesium aluminum borosilicate glass. Magnesium aluminum borosilicate glass with a lower softening point can promote low-temperature densification. Too little magnesium aluminum borosilicate glass makes low-temperature sintering difficult, while too much will reduce the performance of the material itself. Zinc borosilicate glass can precipitate Zn2SiO4 crystal phase with low dielectric loss (tanδ ~ 1×10⁻⁶) during heat treatment. -4 Insufficient zinc borosilicate glass (ZBBS) will reduce the material's performance, while excessive amounts will hinder dense sintering. Only by appropriately controlling the ratio can low-temperature sintering and dielectric properties be balanced. Furthermore, by introducing titanium dioxide as a nucleating agent, Zn₂SiO₄ is preferentially precipitated in the ZBBS instead of the high-loss crystalline phase, and by controlling the temperature coefficient to avoid excessively large temperature coefficients affecting practical applications.

[0028] (3) This invention achieves densification at <900℃ through ceramic / glass multiphase design and compositional control, with thermal conductivity (5.1-5.6 W / mK) superior to conventional LTCC materials (typically <3 W / mK), and dielectric loss (~7×10⁻⁶ W / mK). -4 It meets the requirements of 5G millimeter-wave devices, with a wide sintering window that is easy to control for silver paste matching. It also exhibits good matching when co-fired with Ag electrodes, creating conditions for its application in actual production. Attached Figure Description

[0029] Figure 1 SEM images of low-temperature co-fired ceramic materials prepared in different embodiments and comparative examples are shown, where (a) is comparative example 1, (b) is example 4, (c) is example 5, and (d) is comparative example 2.

[0030] Figure 2The morphology results of the low-temperature co-fired ceramic material in Example 4, co-fired with Ag at 890℃, are shown in (a) as a microscopic morphology image of the sample surface and (b) as an EDS elemental line scan image. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments and the accompanying drawings. Those skilled in the art will understand that the following embodiments are only for illustrative purposes and should not be construed as limiting the scope of protection of the present invention. In the following embodiments, all raw materials are known commercially available products.

[0032] This invention provides a low dielectric constant and high thermal conductivity LTCC material. By mass, the composite material comprises: 20%–48% zinc borosilicate glass powder; 6%–26% magnesium aluminum borosilicate glass powder; 2%–10% boron nitride; 30%–60% zinc aluminate; and 4%–10% titanium dioxide. The total amount of zinc borosilicate glass, magnesium aluminum borosilicate glass, boron nitride, zinc aluminate, and titanium dioxide added is 100 parts by mass. The mass ratio of the total amount of zinc borosilicate glass and magnesium aluminum borosilicate glass to zinc aluminate is 1–2:1; the mass ratio of zinc borosilicate glass to magnesium aluminum borosilicate glass is 1.5–5:1.

[0033] In one embodiment, the zinc borosilicate glass comprises the following raw materials by weight percentage: 30%~70% ZnO, 10%~60% B2O3, 5%~30% SiO2, and 1%~3% Bi2O3, 1%~5% R2O, and 1%~5% MO, wherein: R2O is at least one of Li2O and K2O; and MO is one or more of CuO, CaO, and MnO2.

[0034] In one embodiment, the magnesium aluminum borosilicate glass composition includes 10%~20% MgO, 10%~20% Al2O3, 12%~25% B2O3, 45%~65% SiO2, and 1%~3% R2O and 1%~2% MsO, wherein: R2O is at least one of Li2O, K2O, and Na2O; and MsO is one or more of CuO, CaO, MnO2, ZnO, and Na2O.

[0035] This invention also provides a method for preparing a low dielectric constant and high thermal conductivity LTCC material, comprising the following steps:

[0036] a. A mixture of 20%~48% zinc borosilicate glass, 6%~26% magnesium aluminum borosilicate glass, 2%~10% boron nitride, 30%~60% zinc aluminate, and 4%~10% titanium dioxide by weight percentage, with the sum of zinc borosilicate glass, magnesium aluminum borosilicate glass, boron nitride, zinc aluminate, and titanium dioxide being 100%, is ball-milled for 16h~24h using ethanol as a solvent and then dried to obtain low-temperature co-fired ceramic powder.

[0037] b. The obtained ceramic powder is added to a PVA solution with a weight content of 5%~8% and ground into granules. After sieving, it is pressed into a green body with a diameter of 15mm and a thickness of 7.5mm under a pressure of 5~20MPa. The sintering curve is as follows: the temperature is raised from room temperature to 400~500℃ at a rate of 0.5~2℃ / min and held for 1~2h. Then the temperature is raised to 870~900℃ at a rate of 3~10℃ / min and held for 30~60min to obtain LTCC material with low dielectric constant, low dielectric loss and high thermal conductivity.

[0038] The preparation method of zinc borosilicate glass or magnesium aluminum borosilicate glass in step a is as follows:

[0039] A. The zinc borosilicate glass comprises the following raw materials by weight percentage: 30%~70% ZnO, 10%~60% B2O3, 5%~30% SiO2, 1%~3% Bi2O3, 1%~5% R2O, and 1%~5% MO, wherein: R2O is at least one of Li2O and K2O; MO is one or more of CuO, CaO, and MnO2, and the total composition of the zinc borosilicate glass is 100%, and the components of the zinc borosilicate glass are mixed evenly to obtain raw material powder; or, the magnesium aluminum borosilicate glass composition comprises 10%~20% MgO, 10%~20% Al2O3, 12%~25% B2O3, 45%~65% SiO2, and 1%~3% R2O and 1%~2% MsO, Wherein: R2O is at least one of Li2O, K2O, and Na2O; MsO is one or more of CuO, CaO, MnO2, ZnO, and Na2O; the total composition of the magnesium aluminum borosilicate glass is 100%; and the components of the magnesium aluminum borosilicate glass are mixed evenly to obtain the raw material powder.

[0040] B. Melt the zinc borosilicate glass raw material powder in step A at a high temperature of 1300℃~1400℃ for 1~2 hours to obtain a transparent glass melt; or, melt the magnesium aluminum borosilicate glass raw material powder in step A at a high temperature of 1450℃~1550℃ for 1~2 hours to obtain a transparent glass melt.

[0041] C. Quench the molten glass from step B into deionized water to obtain transparent glass shards.

[0042] D. Crush the glass shards from step C, put them into a ball mill jar, and ball mill them with anhydrous ethanol as the medium, in a mass ratio of 1:1:5. Dry the mixture to obtain glass powder.

[0043] The low dielectric constant and high thermal conductivity LTCC material and its preparation method of the present invention will be further illustrated below through some specific embodiments and comparative examples.

[0044] Example 1

[0045] 1. First, zinc borosilicate glass powder is prepared by mixing the following components: 60% ZnO, 20% B2O3 (H3BO3 is used instead of B2O3 in this example because B2O3 is unstable), 10% SiO2, 3% Li2O, 2% CuO, 2% Bi2O3, 2% CaO, and 1% MnO2. After dry mixing, the mixture is kept at 1350℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0046] 2. Next, magnesium aluminum borosilicate glass powder is prepared: the following components are prepared: 15% MgO, 8% Al2O3, 21% B2O3, 51% SiO2, 2% Li2O, 2% CaO, and 1% Na2O. After being dry-mixed evenly, the mixture is kept at 1550℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0047] 3. Next, prepare zinc aluminate ceramic powder: Take samples according to the molar ratio of Al2O3:ZnO=1:1, add the powder, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, place it in a planetary ball mill for grinding, and after drying, put the crucible containing the powder into a high-temperature furnace and keep it at 1150℃ for 3 hours to obtain pure phase zinc aluminate. Add zinc aluminate, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, perform a second ball milling, and after drying, obtain zinc aluminate powder.

[0048] 4. Next, prepare LTCC ceramic powder: The zinc borosilicate glass, magnesium aluminum borosilicate glass and boron nitride, zinc aluminate and oxide obtained above are mixed according to the proportions in Table 1. Then, the mixture is ball-milled for 17 hours according to the ratio of powder:ethanol:grinding ball = 1:2:10. The mixture is discharged, dried and passed through a 50-mesh sieve to obtain LTCC ceramic powder.

[0049] 5. Finally, low dielectric constant and high thermal conductivity LTCC material was prepared: 5% PVA solution was added to the sieved composite powder for granulation. Then, it was dry-pressed into cylindrical green bodies with a thickness of 7.5mm and a diameter of 15mm using a mold. Next, it was placed in a high-throughput furnace for debinding and sintering: during the debinding process, the temperature was increased to 500℃ at 1℃ / min and held for 1h. Then, the temperature was increased to 870℃ at 5℃ / min and held for 1h for sintering. The performance of the tested round blocks is shown in Table 2.

[0050] Example 2

[0051] 1. First, zinc borosilicate glass powder is prepared by mixing the following components: 60% ZnO, 20% B2O3 (H3BO3 is used instead of B2O3 in this example because B2O3 is unstable), 10% SiO2, 3% Li2O, 2% CuO, 2% Bi2O3, 2% CaO, and 1% MnO2. After dry mixing, the mixture is kept at 1350℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0052] 2. Next, magnesium aluminum borosilicate glass powder is prepared: the following components are prepared: 15% MgO, 8% Al2O3, 21% B2O3, 51% SiO2, 2% Li2O, 2% CaO, and 1% Na2O. After being dry-mixed evenly, the mixture is kept at 1550℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0053] 3. Next, prepare zinc aluminate ceramic powder: Take samples according to the molar ratio of Al2O3:ZnO=1:1, add the powder, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, place it in a planetary ball mill for grinding, and after drying, put the crucible containing the powder into a high-temperature furnace and keep it at 1150℃ for 3 hours to obtain pure phase zinc aluminate. Add zinc aluminate, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, perform a second ball milling, and after drying, obtain zinc aluminate powder.

[0054] 4. Next, prepare LTCC ceramic powder: The zinc borosilicate glass, magnesium aluminum borosilicate glass and boron nitride, zinc aluminate and oxide obtained above are mixed according to the proportions in Table 1. Then, the mixture is ball-milled for 17 hours according to the ratio of powder:ethanol:grinding ball = 1:2:10. The mixture is discharged, dried and passed through a 50-mesh sieve to obtain LTCC ceramic powder.

[0055] 5. The sieved composite powder was granulated by adding 5% PVA solution. Then, it was dry-pressed into cylindrical green bodies with a thickness of 7.5mm and a diameter of 15mm using a mold. The green bodies were then placed in a high-throughput furnace for debinding and sintering: the debinding process was carried out by raising the temperature to 500℃ at a rate of 1℃ / min and holding for 1 hour, followed by raising the temperature to 880℃ at a rate of 5℃ / min and holding for 1 hour for sintering. The performance of the tested round blocks is shown in Table 2.

[0056] Example 3

[0057] 1. First, zinc borosilicate glass powder is prepared by mixing the following components: 60% ZnO, 20% B2O3 (H3BO3 is used instead of B2O3 in this example because B2O3 is unstable), 10% SiO2, 3% Li2O, 2% CuO, 2% Bi2O3, 2% CaO, and 1% MnO2. After dry mixing, the mixture is kept at 1350℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0058] 2. Next, magnesium aluminum borosilicate glass powder is prepared: the following components are prepared: 15% MgO, 8% Al2O3, 21% B2O3, 51% SiO2, 2% Li2O, 2% CaO, and 1% Na2O. After being dry-mixed evenly, the mixture is kept at 1550℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0059] 3. Next, prepare zinc aluminate ceramic powder: Take samples according to the molar ratio of Al2O3:ZnO=1:1, add the powder, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, place it in a planetary ball mill for grinding, and after drying, put the crucible containing the powder into a high-temperature furnace and keep it at 1150℃ for 3 hours to obtain pure phase zinc aluminate. Add zinc aluminate, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, perform a second ball milling, and after drying, obtain zinc aluminate powder.

[0060] 4. Next, prepare LTCC ceramic powder: The zinc borosilicate glass, magnesium aluminum borosilicate glass and boron nitride, zinc aluminate and oxide obtained above are mixed according to the proportions in Table 1. Then, the mixture is ball-milled for 17 hours according to the ratio of powder:ethanol:grinding ball = 1:2:10. The mixture is discharged, dried and passed through a 50-mesh sieve to obtain LTCC ceramic powder.

[0061] 5. The sieved composite powder was granulated by adding 5% PVA solution. Then, it was dry-pressed into cylindrical green bodies with a thickness of 7.5mm and a diameter of 15mm using a mold. The green bodies were then placed in a high-throughput furnace for debinding and sintering: the debinding process was carried out by raising the temperature to 500℃ at a rate of 1℃ / min and holding for 1 hour, followed by raising the temperature to 880℃ at a rate of 5℃ / min and holding for 1 hour for sintering. The performance of the tested round blocks is shown in Table 2.

[0062] Example 4

[0063] 1. First, zinc borosilicate glass powder is prepared by mixing the following components: 60% ZnO, 20% B2O3 (H3BO3 is used instead of B2O3 in this example because B2O3 is unstable), 10% SiO2, 3% Li2O, 2% CuO, 2% Bi2O3, 2% CaO, and 1% MnO2. After dry mixing, the mixture is kept at 1350℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0064] 2. Next, magnesium aluminum borosilicate glass powder is prepared: the following components are prepared: 15% MgO, 8% Al2O3, 21% B2O3, 51% SiO2, 2% Li2O, 2% CaO, and 1% Na2O. After being dry-mixed evenly, the mixture is kept at 1550℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0065] 3. Next, prepare zinc aluminate ceramic powder: Take samples according to the molar ratio of Al2O3:ZnO=1:1, add the powder, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, place it in a planetary ball mill for grinding, and after drying, put the crucible containing the powder into a high-temperature furnace and keep it at 1150℃ for 3 hours to obtain pure phase zinc aluminate. Add zinc aluminate, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, perform a second ball milling, and after drying, obtain zinc aluminate powder.

[0066] 4. Next, prepare LTCC ceramic powder: The zinc borosilicate glass, magnesium aluminum borosilicate glass and boron nitride, zinc aluminate and oxide obtained above are mixed according to the proportions in Table 1. Then, the mixture is ball-milled for 17 hours according to the ratio of powder:ethanol:grinding ball = 1:2:10. The mixture is discharged, dried and passed through a 50-mesh sieve to obtain LTCC ceramic powder.

[0067] 5. The sieved composite powder was granulated by adding 5% PVA solution. Then, it was dry-pressed into cylindrical green bodies with a thickness of 7.5mm and a diameter of 15mm using a mold. The green bodies were then placed in a high-throughput furnace for debinding and sintering: the debinding process was carried out by raising the temperature to 500℃ at a rate of 1℃ / min and holding for 1 hour, followed by raising the temperature to 890℃ at a rate of 5℃ / min and holding for 1 hour for sintering. The performance of the tested round blocks is shown in Table 2.

[0068] Example 5

[0069] 1. First, zinc borosilicate glass powder is prepared by mixing the following components: 60% ZnO, 20% B2O3 (H3BO3 is used instead of B2O3 in this example because B2O3 is unstable), 10% SiO2, 3% Li2O, 2% CuO, 2% Bi2O3, 2% CaO, and 1% MnO2. After dry mixing, the mixture is kept at 1350℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0070] 2. Next, magnesium aluminum borosilicate glass powder is prepared: the following components are prepared: 15% MgO, 8% Al2O3, 21% B2O3, 51% SiO2, 2% Li2O, 2% CaO, and 1% Na2O. After being dry-mixed evenly, the mixture is kept at 1550℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0071] 3. Next, prepare zinc aluminate ceramic powder: Take samples according to the molar ratio of Al2O3:ZnO=1:1, add the powder, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, place it in a planetary ball mill for grinding, and after drying, put the crucible containing the powder into a high-temperature furnace and keep it at 1150℃ for 3 hours to obtain pure phase zinc aluminate. Add zinc aluminate, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, perform a second ball milling, and after drying, obtain zinc aluminate powder.

[0072] 4. Next, prepare LTCC ceramic powder: The zinc borosilicate glass, magnesium aluminum borosilicate glass and boron nitride, zinc aluminate and oxide obtained above are mixed according to the proportions in Table 1. Then, the mixture is ball-milled for 17 hours according to the ratio of powder:ethanol:grinding ball = 1:2:10. The mixture is discharged, dried and passed through a 50-mesh sieve to obtain LTCC ceramic powder.

[0073] 5. The sieved composite powder was granulated by adding 5% PVA solution. Then, it was dry-pressed into cylindrical green bodies with a thickness of 7.5mm and a diameter of 15mm using a mold. The green bodies were then placed in a high-throughput furnace for debinding and sintering: the debinding process was carried out by raising the temperature to 500℃ at a rate of 1℃ / min and holding for 1 hour, followed by raising the temperature to 900℃ at a rate of 5℃ / min and holding for 1 hour for sintering. The performance of the tested round blocks is shown in Table 2.

[0074] Example 6

[0075] 1. First, zinc borosilicate glass powder is prepared by mixing the following components: 60% ZnO, 20% B2O3 (H3BO3 is used instead of B2O3 in this example because B2O3 is unstable), 10% SiO2, 3% Li2O, 2% CuO, 2% Bi2O3, 2% CaO, and 1% MnO2. After dry mixing, the mixture is kept at 1350℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0076] 2. Next, magnesium aluminum borosilicate glass powder is prepared: the following components are prepared: 15% MgO, 8% Al2O3, 21% B2O3, 51% SiO2, 2% Li2O, 2% CaO, and 1% Na2O. After being dry-mixed evenly, the mixture is kept at 1550℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0077] 3. Next, prepare zinc aluminate ceramic powder: Take samples according to the molar ratio of Al2O3:ZnO=1:1, add the powder, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, place it in a planetary ball mill for grinding, and after drying, put the crucible containing the powder into a high-temperature furnace and keep it at 1150℃ for 3 hours to obtain pure phase zinc aluminate. Add zinc aluminate, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, perform a second ball milling, and after drying, obtain zinc aluminate powder.

[0078] 4. Next, prepare LTCC ceramic powder: The zinc borosilicate glass, magnesium aluminum borosilicate glass and boron nitride, zinc aluminate and oxide obtained above are mixed according to the proportions in Table 1. Then, the mixture is ball-milled for 17 hours according to the ratio of powder:ethanol:grinding ball = 1:2:10. The mixture is discharged, dried and passed through a 50-mesh sieve to obtain LTCC ceramic powder.

[0079] 5. The sieved composite powder was granulated by adding 5% PVA solution. Then, it was dry-pressed into cylindrical green bodies with a thickness of 7.5mm and a diameter of 15mm using a mold. The green bodies were then placed in a high-throughput furnace for debinding and sintering: the debinding process was carried out by raising the temperature to 500℃ at a rate of 1℃ / min and holding for 1 hour, followed by raising the temperature to 900℃ at a rate of 5℃ / min and holding for 1 hour for sintering. The performance of the tested round blocks is shown in Table 2.

[0080] Comparative Example 1

[0081] 1. First, zinc borosilicate glass powder is prepared by mixing the following components: 60% ZnO, 20% B2O3 (H3BO3 is used instead of B2O3 in this example because B2O3 is unstable), 10% SiO2, 3% Li2O, 2% CuO, 2% Bi2O3, 2% CaO, and 1% MnO2. After dry mixing, the mixture is kept at 1350℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0082] 2. Next, magnesium aluminum borosilicate glass powder is prepared: the following components are prepared: 15% MgO, 8% Al2O3, 21% B2O3, 51% SiO2, 2% Li2O, 2% CaO, and 1% Na2O. After being dry-mixed evenly, the mixture is kept at 1550℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0083] 3. Next, prepare zinc aluminate ceramic powder: Take samples according to the molar ratio of Al2O3:ZnO=1:1, add the powder, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, place it in a planetary ball mill for grinding, and after drying, put the crucible containing the powder into a high-temperature furnace and keep it at 1150℃ for 3 hours to obtain pure phase zinc aluminate. Add zinc aluminate, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, perform a second ball milling, and after drying, obtain zinc aluminate powder.

[0084] 4. Next, prepare LTCC ceramic powder: The zinc borosilicate glass, magnesium aluminum borosilicate glass and boron nitride, zinc aluminate and oxide obtained above are mixed according to the proportions in Table 1. Then, the mixture is ball-milled for 17 hours according to the ratio of powder:ethanol:grinding ball = 1:2:10. The mixture is discharged, dried and passed through a 50-mesh sieve to obtain LTCC ceramic powder.

[0085] 5. The sieved composite powder was granulated by adding 5% PVA solution. Then, it was dry-pressed into cylindrical green bodies with a thickness of 7.5mm and a diameter of 15mm using a mold. The green bodies were then placed in a high-throughput furnace for debinding and sintering: the debinding process was carried out by raising the temperature to 500℃ at a rate of 1℃ / min and holding for 1 hour, followed by raising the temperature to 900℃ at a rate of 5℃ / min and holding for 1 hour for sintering. The performance of the tested round blocks is shown in Table 2.

[0086] Comparative Example 2

[0087] 1. First, zinc borosilicate glass powder is prepared by mixing the following components: 60% ZnO, 20% B2O3 (H3BO3 is used instead of B2O3 in this example because B2O3 is unstable), 10% SiO2, 3% Li2O, 2% CuO, 2% Bi2O3, 2% CaO, and 1% MnO2. After dry mixing, the mixture is kept at 1350℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0088] 2. Next, magnesium aluminum borosilicate glass powder is prepared: the following components are prepared: 15% MgO, 8% Al2O3, 21% B2O3, 51% SiO2, 2% Li2O, 2% CaO, and 1% Na2O. After being dry-mixed evenly, the mixture is kept at 1550℃ for 2 hours to obtain a high-temperature glass melt. The obtained glass melt is poured into deionized water for cooling and quenching. Finally, the quenched glass slag, ethanol, and grinding balls are added to a grinding jar in a ratio of 1:1:5 and ground in a planetary ball mill. Finally, the glass powder is dried to obtain the glass powder.

[0089] 3. Next, prepare zinc aluminate ceramic powder: Take samples according to the molar ratio of Al2O3:ZnO=1:1, add the powder, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, place it in a planetary ball mill for grinding, and after drying, put the crucible containing the powder into a high-temperature furnace and keep it at 1150℃ for 3 hours to obtain pure phase zinc aluminate. Add zinc aluminate, ethanol, and grinding balls to the grinding jar in a ratio of 1:1:8, perform a second ball milling, and after drying, obtain zinc aluminate powder.

[0090] 4. Next, prepare LTCC ceramic powder: The zinc borosilicate glass, magnesium aluminum borosilicate glass and boron nitride, zinc aluminate and oxide obtained above are mixed according to the proportions in Table 1. Then, the mixture is ball-milled for 17 hours according to the ratio of powder:ethanol:grinding ball = 1:2:10. The mixture is discharged, dried and passed through a 50-mesh sieve to obtain LTCC ceramic powder.

[0091] 5. The sieved composite powder was granulated by adding 5% PVA solution. Then, it was dry-pressed into cylindrical green bodies with a thickness of 7.5mm and a diameter of 15mm using a mold. The green bodies were then placed in a high-throughput furnace for debinding and sintering: the debinding process was carried out by raising the temperature to 500℃ at a rate of 1℃ / min and holding for 1 hour, followed by raising the temperature to 880℃ at a rate of 5℃ / min and holding for 1 hour for sintering. The performance of the tested round blocks is shown in Table 2.

[0092] Table 2 shows the overall performance of each embodiment. Dielectric properties were measured using an Agilent 8719ET vector network analyzer, and the dielectric constant εᵣ and dielectric loss tanδ, as well as the temperature coefficient of resonant frequency τ, were determined according to the Hakki-Coleman resonant cavity method. f Measurements were taken within a temperature range of 25–80℃, and the result was obtained using the formula: τ f =(f 80 -f 25 ) / (f 25 The values ​​are calculated as (×55), where f80 and f25 are the resonant frequencies at 80℃ and 25℃, respectively. The bending strength test is performed using a three-point bending tester, and the thermal conductivity test is performed using a Hot Disk TPS 2500S thermal conductivity meter.

[0093] As shown in Table 2, Example 4 has better performance. By adjusting the ratio between the components, the dielectric loss of the material can be reduced and the thermal conductivity and bending strength can be enhanced. Figure 1 (a) Figure 1 Image (d) shows the SEM microstructure of samples prepared by different embodiments and comparative examples of the present invention under sintering at 870℃~900℃. It can be found that the composite material system can obtain a highly densified internal structure at a lower sintering temperature. Among them, the morphology of Example 4 is the most dense. The ceramic grains of the material prepared by the present invention are about 2~3μm, with uniform size and good density. Figure 2 (a) Figure 2 (b) shows the XRD and EDS line scans of the glass / ceramic composite material after co-firing with Ag in Example 4 of the present invention. It was found that the compatibility with Ag was good at a sintering temperature of 890℃, which created conditions for subsequent actual production and use.

[0094] Table 1 shows the component list for each embodiment.

[0095]

[0096] Table 2 shows a comparison of the overall performance of each embodiment.

[0097]

[0098] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A low dielectric constant high thermal conductivity (LTCC) material, characterized in that, The zinc borosilicate glass, the magnesium aluminum borosilicate glass, the boron nitride, the zinc aluminate and the titanium dioxide have a total mass percentage of 100%; the mass ratio of the total amount of the zinc borosilicate glass and the magnesium aluminum borosilicate glass to the zinc aluminate is 1-2:1; and the mass ratio of the zinc borosilicate glass to the magnesium aluminum borosilicate glass is 1.5-5:

1. The zinc borosilicate glass comprises the following raw materials in percentage by mass: 30-70% ZnO, 10-60% B2O3, 5-30% SiO2, 1-3% Bi2O3, 1-5% R2O and 1-5% MO, wherein R2O is at least one of Li2O and K2O, and MO is one or more of CuO, CaO and MnO2. The magnesium aluminum borosilicate glass comprises the following components: 10-20% MgO, 10-20% Al2O3, 12-25% B2O3, 45-65% SiO2, 1-3% R2O and 1-2% MsO, wherein R2O is at least one of Li2O, K2O and Na2O, and MsO is one or more of CuO, CaO, MnO2, ZnO and Na2O.

2. The method for preparing the low dielectric constant and high thermal conductivity LTCC material according to claim 1, characterized in that, The method comprises the following steps: The zinc borosilicate glass, the magnesium aluminum borosilicate glass, the boron nitride, the zinc aluminate and the titanium dioxide are ball-milled with ethanol as a solvent and then dried to obtain low-temperature co-fired ceramic powder; The obtained low-temperature co-fired ceramic powder is added to a PVA solution, ground and granulated, sieved and then pressed into a green body; The green body is high-temperature sintered to obtain an LTCC material with low dielectric constant, low dielectric loss and high thermal conductivity. The ball milling time in the preparation process of the low-temperature co-fired ceramic powder is 16-24 h.

3. The method of claim 2, wherein, The PVA solution has a mass content of 5-8% of the low-temperature co-fired ceramic powder.

4. The method of claim 2, wherein, The high-temperature sintering conditions of the green body are as follows: the temperature is raised from room temperature to 400-500 ℃ at a rate of 0.5-2 ℃ / min and then kept for 1-2 h, and then the temperature is raised to 870-900 ℃ at a rate of 3-10 ℃ / min and then kept for 30-60 min.

5. The method of claim 2, wherein, The preparation of the zinc borosilicate glass comprises the following steps:

6. The method of claim 2, wherein, The ZnO, B2O3, SiO2, Bi2O3, R2O and MO are uniformly mixed and then high-temperature melted at 1300-1400 ℃ for 1-2 h to obtain transparent glass liquid; The glass liquid is quenched into deionized water to obtain transparent glass slag; The glass slag is broken, put into a ball mill tank and ball-milled with anhydrous ethanol as a medium, and then dried to obtain glass powder. The preparation of the magnesium aluminum borosilicate glass comprises the following steps:

7. The method of claim 2 wherein, The glass liquid is quenched into deionized water to obtain transparent glass slag; MgO, Al203, B203, Si02, R20, M S After mixing uniformly, the glass liquid is obtained by high temperature smelting at 1450-1550℃ for 1-2h. The glass slag is broken, put into a ball mill tank and ball-milled with anhydrous ethanol as a medium, and then dried to obtain glass powder. In the preparation process of the zinc borosilicate glass and the magnesium aluminum borosilicate glass, the mass ratio of the glass slag, the anhydrous ethanol and the grinding balls is 1:1:

5.

8. The method of claim 6 or 7, wherein, ​

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