A low dielectric constant low temperature co-fired ceramic material system, preparation method and application thereof

Abstract

The application discloses a low dielectric constant low-temperature co-fired ceramic material system, a preparation method and application, and belongs to the technical field of electronic ceramic materials. In mass percentage, components of the ceramic material system are as follows: a ceramic matrix is 93-99 wt%; a sintering aid is 1-7 wt%; a composition expression of the ceramic matrix is xBaO-yCuO-zSiO2, wherein x in the xBaO-yCuO-zSiO2 ranges from 32 wt% to 44 wt%, y ranges from 16 wt% to 30 wt%, and z ranges from 30 wt% to 52 wt%; and the sintering aid comprises at least one of Li2O-B2O3-SiO2-CaO-Al2O3 glass powder, LiF and BaO-CuO-B2O3 oxide.

Description

Technical Field

[0001] This invention belongs to the field of electronic ceramic materials technology, specifically relating to a low dielectric constant low-temperature co-fired ceramic material system, its preparation method, and its application. Background Technology

[0002] Low-temperature co-fired ceramic (LTC) technology is one of the mainstream passive integration technologies. By encapsulating electrode materials, ceramic substrates, and electronic components into a single unit, it creates multilayer or three-dimensional circuit boards, enabling high-density wiring and the integration of various passive devices. LTC technology primarily utilizes dielectric ceramic materials such as Ag, Cu, and Au, which are excellent conductors with low coefficients of thermal expansion and are sintered at low temperatures. Therefore, it offers advantages such as low high-frequency transmission loss, high thermal shock resistance, high integration, and high assembly density. With the trend towards miniaturization, integration, high frequency, multifunctionality, and high reliability in electronic products, LTC technology can provide a reliable solution, playing a particularly important role in 5G millimeter-wave communication fields such as antenna modules, filters, duplexers, and ceramic substrates.

[0003] The core material of low-temperature co-fired ceramic technology is low-temperature co-fired ceramic powder. Based on the characteristics of the technology, the main technical indicators of low-temperature co-fired ceramic powder used in microwave and millimeter-wave applications include a suitable sintering temperature (800℃~1000℃), compatibility with Ag, Cu, and Au electrodes (Ag electrodes being the most preferred), a low dielectric constant (5~10), dielectric loss less than 0.001 at the applied frequency, good thermal properties (such as thermal expansion matching with semiconductors like Si), and excellent flexural strength. Simultaneously, low-temperature co-fired ceramic powder is compatible with casting technology, making commercial implementation feasible. However, the development of low-temperature co-fired ceramic powder for millimeter-wave applications is more challenging, and currently, there are few reported millimeter-wave powders, and their related technical indicators are still insufficient. For example, Chinese invention patent CN115353383B discloses a (Zn...) 0.9 Cu 0.1 ) 0.15 Nb 0.3 (Ti 0.9 Zr 0.1 ) 0.55O2 low-temperature co-fired ceramic materials can be sintered to a dense state at 850℃~900℃, but their dielectric constant is 52.7. An excessively high dielectric constant is detrimental to reducing transmission delay under millimeter-wave conditions, making them unsuitable as high-frequency substrate materials. For example, Chinese invention patent CN114956798B provides a high-Q, low-temperature drift, low-K ceramic material with ceramic phases (1-x)SiO2-xMg2SiO4 and trace amounts of Bi2O3 and CuO. While exhibiting good dielectric properties, the sintering temperature remains at 1250℃~1350℃, an excessively high temperature that cannot meet the co-firing requirements for good conductors such as Ag, Cu, and Au. Another example is Chinese invention patent CN114685152B, which discloses a low-temperature co-fired ceramic material with Mg2SiO4 as the main crystalline phase and low-K, low-melting-point glass powder. Its high-frequency dielectric properties and flexural strength meet the technical requirements, but key indicators such as co-firing with Ag electrodes and thermal matching are not described.

[0004] Existing related reports include BaCuSi4O 10 The microstructure and microwave dielectric properties of the single-phase ceramic are described, but no further optimization is made for the technical specifications of low-temperature co-fired ceramics. Chinese patent CN108249902B discloses a silicate-based microwave dielectric ceramic composed of Ba-Sr / Ca-Cu / Mg, which features low dielectric strength and high quality factor, but its composition consists only of ceramic phases, making it impossible to control the sintering temperature range and thus not meeting the requirements of low-temperature co-fired technology. Chinese patent CN115947587A discloses a Ba... x Sr y Bi z CuSi2O6 microwave dielectric ceramics are characterized by low-temperature sintering and low K, but the technical route uses trace amounts of Sr and Bi to replace the main crystalline phase of BaCuSi2O6. At the same time, the compatibility of this system with tape casting technology is not explained.

[0005] BaO-CuO-SiO2 material was first used as a dye such as Chinese blue, and its main phase components include BaCuSi4O 10 BaCuSi₂O₆, Ba₂CuSi₂O₇, BaCu₂Si₂O₇. Chinese patent CN105098586B provides a BaCuSi₄O₆. 10 Two-dimensional crystals are used as materials for saturated absorbers, while ceramic materials are used as microwave dielectrics. The application of BaO-CuO-SiO2 ceramic materials in low-temperature co-fired ceramic technology still faces several technical and process challenges, particularly ensuring that powder properties meet relevant technical specifications, matching the powder with Ag electrodes during co-firing, and adapting the casting process.

[0006] In summary, there are few low-dielectric-constant low-temperature co-fired ceramic materials in the existing technology, and their overall performance indicators may be insufficient. Therefore, developing a low-dielectric-constant low-temperature co-fired ceramic material system for millimeter-wave communication, achieving a series of low-dielectric-constant materials, matching with casting technology, and achieving good thermal matching and mechanical properties is a challenging and highly rewarding task. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the present invention aims to provide a low-dielectric-constant low-temperature co-fired ceramic material system, its preparation method, and its application. By optimizing the formulation of the material system, sintering at 800℃ to 1000℃ achieves densification, resulting in a low-temperature co-fired ceramic material system that possesses low dielectric constant, low dielectric loss, low thermal expansion temperature coefficient, good resonant frequency temperature coefficient, and good flexural strength. This provides a powder for low-temperature co-fired ceramic technology used in millimeter-wave applications, contributing to the realization of low-loss, high-reliability, and high-integration millimeter-wave communication.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] This invention provides a low-dielectric-constant low-temperature co-fired ceramic material system, the composition of which, by mass percentage, is as follows:

[0010] The ceramic matrix is ​​93–99 wt%; the sintering aid is 1–7 wt%.

[0011] The compositional formula of the ceramic matrix is ​​xBaO-yCuO-zSiO2, where...

[0012] In the xBaO-yCuO-zSiO2, x ranges from 32 to 44 wt%, y ranges from 16 to 30 wt%, and z ranges from 30 to 52 wt%.

[0013] The sintering aid includes at least one of Li2O-B2O3-SiO2-CaO-Al2O3 glass powder, LiF, and BaO-CuO-B2O3 oxide.

[0014] In the specific implementation process, the Li2O-B2O3-SiO2-CaO-Al2O3 glass powder comprises 32-33 wt% Li2O, 44-45 wt% B2O3, 15-16 wt% SiO2, 2-3 wt% CaO, and 4-6 wt% Al2O3 by mass percentage.

[0015] In the specific implementation process, the BaO-CuO-B2O3 oxide comprises 34-58 wt% BaO, 26-35 wt% CuO, and 13-31 wt% B2O3 by mass percentage.

[0016] In practical implementation, the microwave dielectric constant of the low-dielectric-constant low-temperature co-fired ceramic material system is between 5 and 8, and the dielectric loss is <10. -3 The temperature coefficient of the resonant frequency is -8 to -37 ppm / ℃ at temperatures ranging from 25℃ to 85℃.

[0017] In specific implementation, within the range of room temperature to 400°C, the coefficient of thermal expansion of the low dielectric constant low-temperature co-fired ceramic material system is 0.5 to 5 ppm / °C.

[0018] In specific implementation, the three-point flexural strength of the low dielectric constant low-temperature co-fired ceramic material system is 70-120 MPa.

[0019] In practice, the low dielectric constant low-temperature co-fired ceramic material system is compatible with Ag and Cu electrodes.

[0020] The present invention also provides a method for preparing a low dielectric constant low-temperature co-fired ceramic material system according to any one of the claims, comprising the following steps:

[0021] S1: The raw materials BaCO3, CuO, and SiO2 are prepared according to the composition formula of the ceramic matrix xBaO-yCuO-zSiO2, and then ball-milled and dried. After pre-firing at a set temperature and holding for a set time, the ceramic matrix is ​​obtained by sieving. Select the sintering aid.

[0022] S2: The low-temperature co-fired ceramic material powder is obtained by mixing the ceramic matrix and sintering aid according to the composition of the low dielectric constant low-temperature co-fired ceramic material system, followed by ball milling, drying and sieving.

[0023] S3: The low-temperature co-fired ceramic material system powder is combined with PVA binder, granulated, and then pressed into a mold to obtain a molded product. The product is then heated to a first set temperature at a first heating rate and held for a first set time to remove the binder. The product is then heated to a second set temperature at a second heating rate and sintered to obtain a low-dielectric-constant low-temperature co-fired ceramic.

[0024] In the specific implementation process, in S1, the set temperature is 900℃~1000℃, and the set time is 3h; during the pre-firing process, the temperature is increased or decreased at a rate of 2~4℃ / min.

[0025] In S3, the first heating rate is 1℃ / min, the first set temperature is 550℃, and the first set time is 4h; the second heating rate is 2~4℃ / min, and the second set temperature is 800℃~1000℃.

[0026] The present invention also provides the application of a low dielectric constant low-temperature co-fired ceramic material system according to any one of the claims in the preparation of casting slurry, casting raw material tape and ceramic substrate.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention provides a low-dielectric-constant low-temperature co-fired ceramic material system, comprising a ceramic matrix and a sintering aid. Firstly, by changing the xBaO-yCuO-zSiO2 ratio and the pre-firing temperature, the types of ceramic crystalline phases are controlled, thereby achieving operability in properties such as dielectric constant and coefficient of thermal expansion. Its main phase composition includes BaCuSi4O 10 The materials used include BaCuSi2O6 and BaCu2Si2O7. Secondly, the selection of sintering aids effectively wets the main crystalline phases while ensuring they do not react with the ceramic phase, thus avoiding excessive degradation of the microstructure and surface morphology. A reasonable ratio of various sintering aids enables dense sintering at 800℃–1000℃, meeting the temperature requirements for co-firing Ag and Cu. Simultaneously, combined with adaptation to the tape casting process, good surface smoothness and printing characteristics are achieved, helping to mitigate the interference of surface roughness and electrode line precision on high-frequency millimeter-wave signals in device development and applications.

[0029] The aforementioned low-dielectric-constant low-temperature co-fired ceramic material system can simultaneously meet multiple LTCC technical specifications, including low-dielectric-constant semi-serialization, Ag co-firing, CTE matching with Si semiconductors, good high-frequency dielectric properties, and good mechanical properties, which can help achieve low loss, high reliability, and high integration in millimeter-wave communication.

[0030] The aforementioned low-dielectric-constant low-temperature co-fired ceramic material system is compatible with casting paste and has initially passed the Ag and Cu electrode paste co-firing compatibility test, establishing feasibility for the implementation of low-temperature co-fired ceramic technology and the preparation of millimeter-wave devices. It is suitable for use in 5G millimeter-wave communication fields such as antenna modules, filters, and ceramic substrates. Attached Figure Description

[0031] Figure 1 The images shown are XRD, SEM, and EDS images of the co-fired Ag in Embodiment 7 of the present invention, wherein Figure (a) is an XRD image and Figure (b) is a SEM and EDS image.

[0032] Figure 2 The images shown are SEM and EDS images of Examples 2 and 4 of the present invention after co-firing with Cu. Figures (a) to (c) are the appearance, SEM and EDS images of Example 2 after co-firing with copper paste, respectively; Figures (d) to (f) are the appearance, SEM and EDS images of Example 4 after co-firing with copper paste, respectively.

[0033] Figure 3This is a schematic diagram of the substrate of an embodiment of the present invention;

[0034] Figure 4 Figure (a) and Figure (b) are SEM images of the substrate after sintering in an embodiment of the present invention. Detailed Implementation

[0035] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0036] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0037] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0038] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0039] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0040] This invention provides a low dielectric constant low-temperature co-fired ceramic material system, its preparation method, and its application.

[0041] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0042] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0043] The first aspect of this invention provides a low-dielectric-constant low-temperature co-fired ceramic material system, wherein the composition of the low-dielectric-constant low-temperature co-fired ceramic material system is as follows, by mass percentage:

[0044] The ceramic matrix is ​​93–99 wt%; the sintering aid is 1–7 wt%.

[0045] The compositional formula of the ceramic matrix is ​​xBaO-yCuO-zSiO2, wherein x in xBaO-yCuO-zSiO2 ranges from 32 to 44 wt%, y ranges from 16 to 30 wt%, and z ranges from 30 to 52 wt%. By changing the contents of x, y, and z, a matrix including BaCuSi4O2 can be achieved. 10 The formation of the composite main crystalline phases of BaCuSi2O6 and BaCu2Si2O7 can be used to regulate the properties of the material system.

[0046] The sintering aid composition includes at least one of Li2O-B2O3-SiO2-CaO-Al2O3 glass powder, LiF, and BaO-CuO-B2O3 (BCB) oxide.

[0047] In a specific embodiment, the Li2O-B2O3-SiO2-CaO-Al2O3 glass powder comprises 32-33 wt% Li2O, 44-45 wt% B2O3, 15-16 wt% SiO2, 2-3 wt% CaO, and 4-6 wt% Al2O3.

[0048] In a specific embodiment, the BCB oxide comprises 34–58 wt% BaO, 26–35 wt% CuO, and 13–31 wt% B2O3.

[0049] Furthermore, for the low-dielectric-constant low-temperature co-fired ceramic material system prepared by the above method, microwave dielectric properties of the ceramic were tested using a closed-cavity resonator and a split resonator. The results showed that its dielectric constant was between 5 and 8, and its dielectric loss was <10. -3 With the help of a delta temperature chamber, the temperature coefficient of the resonant frequency was measured to be -8 to -37 ppm / ℃ at 25℃ to 85℃.

[0050] The coefficient of thermal expansion of the low-temperature co-fired ceramic material system was measured to be 0.5–5 ppm / ℃ from room temperature to 400℃ using a thermal expansion analyzer.

[0051] The standard-sized samples were tested using a three-point bending tester, and the three-point bending strength of the low-temperature co-fired ceramic material system was found to be 70–120 MPa.

[0052] The low-temperature co-fired ceramic material powder was mixed with pure silver powder, pressed into shape, and sintered at below 900℃ for 2 hours. XRD and EDS tests were then performed. By analyzing the phase composition and elemental distribution of the co-fired samples, it was preliminarily determined that the low-temperature co-fired ceramic material powder is compatible with Ag co-firing.

[0053] The prepared copper electrode slurry was coated onto the surface of the low-temperature co-fired ceramic material powder, and sintered at 950℃~1000℃ for 2 hours under a protective atmosphere. SEM and EDS tests were performed. It was found that the slurry flowed smoothly on the sample surface, and the electron microscope showed that a dense copper film was formed on the surface. EDS determined that the low-temperature co-fired ceramic material powder was compatible with Cu co-firing.

[0054] The second aspect of this invention provides a method for preparing the above-mentioned low-dielectric-constant low-temperature co-fired ceramic material system, the specific steps of which are as follows:

[0055] S1: According to the ceramic matrix formula, the raw materials BaCO3, CuO and SiO2 are prepared, ball-milled and dried, pre-fired at 900℃~1000℃ and held for 3h, and then passed through a 300-mesh sieve to obtain the ceramic matrix; during the pre-firing process, the temperature is raised and lowered at a rate of 2~4℃ / min.

[0056] S2: Prepare a sintering aid;

[0057] S3: The ceramic matrix and sintering aid are mixed according to the composition of the low dielectric constant low temperature co-fired ceramic material system, and then ball-milled, dried and passed through a 200-mesh sieve to obtain the low temperature co-fired ceramic material system powder.

[0058] S4: The obtained low-temperature co-fired ceramic material system powder is combined with PVA binder, granulated, and then pressed into molded products by different shaped molds such as cylinders and cuboids. The binder is removed by heating at 550℃ for 4 hours at a heating rate of 1℃ / min. Then, it is sintered at 800℃ to 1000℃ at a heating rate of 2 to 4℃ / min to obtain the low-temperature co-fired ceramic block. At this time, the ceramic structure is dense and the morphology is good.

[0059] The specific process for preparing the ceramic matrix in S1 above is as follows:

[0060] According to the composition formula of the ceramic matrix as xBaO-yCuO-zSiO2, the raw materials BaCO3, CuO and SiO2 are prepared and ball-milled using pure water and zirconium balls as media. After grinding and drying, the mixture is further pre-fired at 900℃~1000℃ for 3 hours and finally passed through a 300-mesh sieve for later use.

[0061] The powder, zirconium balls, and pure water were ball-milled in a mass ratio of 1:2:2 for 3-6 hours using planetary ball milling or 12-18 hours using a drum ball mill. The powder was then dried in an oven at 80-130°C. The powder pre-calcination process involved temperature increases and decreases of 2-4°C per minute.

[0062] The specific process for preparing the sintering aid in S2 above is as follows:

[0063] The above-mentioned Li2O-B2O3-SiO2-CaO-Al2O3 glass powder, LiF and BCB oxide are ball-milled and mixed in an appropriate proportion, and then dried in an oven at 80℃~130℃.

[0064] If the Li2O-B2O3-SiO2-CaO-Al2O3 glass powder or BCB oxide is used as a sintering aid, the raw materials are weighed according to the specified ratio, and then ball-milled with a powder:zirconia ball:pure water mass ratio of 1:2:2. Planetary ball milling is used for 3–6 hours, or drum ball milling for 12–18 hours. Then, the materials are dried in an oven at 80℃–130℃, followed by subsequent processing. The specific processing methods are as follows:

[0065] Specifically, when using the Li2O-B2O3-SiO2-CaO-Al2O3 glass powder, the raw materials are weighed according to the above method, ball-milled and mixed, dried, and then melted and clarified at 1100℃ for 2 hours. After that, the glass is quenched in pure water, crushed into fine powder, passed through a 300-mesh sieve, and dried for later use.

[0066] Specifically, when using the BCB oxide, it is processed in the above manner, including batching, ball milling, and drying, and then pre-calcined at 400°C for 1 hour at a rate of 3-5°C / min, followed by 600°C for 2 hours. Finally, it is passed through a 300-mesh sieve for later use.

[0067] The present invention also provides a casting slurry adapted to the low dielectric constant low temperature co-fired ceramic material system based on the above-mentioned low dielectric constant low temperature co-fired ceramic material system. The casting slurry is composed of low temperature co-fired ceramic material system powder and organic carrier by mass percentage, and the solid content is controlled at 44-48 wt%. The organic carrier includes solvent, dispersant, binder and plasticizer.

[0068] Specifically, the solvents include at least one of ethanol, butanone, toluene, xylene, methyl ethyl ketone, trichloroethane, and cyclohexanone.

[0069] Specifically, the dispersant includes one of flaxseed oil, fish oil, phosphate esters, ammonium polyacrylate, and methacrylate.

[0070] Specifically, the adhesive includes one of polyvinyl alcohol, polyvinyl butyral, methylcellulose, ethylcellulose, and polymethyl methacrylate.

[0071] Specifically, the plasticizers include at least one of polyethylene glycol, butyl benzyl phthalate, propylene carbonate, glycerin, and polypropylene.

[0072] The above-mentioned casting slurry adapted to the low-temperature co-fired ceramic material system has initially passed the Ag and Cu electrode slurry co-firing compatibility test, establishing the feasibility for the implementation of low-temperature co-fired ceramic technology and the preparation of millimeter-wave devices.

[0073] The present invention also provides a cast raw material tape based on the above-mentioned low dielectric constant low temperature co-fired ceramic material system, which is prepared by coating the cast slurry onto a PET film.

[0074] The present invention also provides a ceramic substrate based on the low dielectric constant low temperature co-fired ceramic material system and a method for preparing the ceramic substrate, based on the aforementioned low dielectric constant low temperature co-fired ceramic material system.

[0075] The above-mentioned method for preparing ceramic substrates includes the following steps:

[0076] S21: A casting slurry is prepared by mixing low-temperature co-fired ceramic material system powder and organic carrier in a high-speed mixer;

[0077] Specifically, the high-speed mixer is set to first rotate at 1000 r / min for 30 min, then at 1200 r / min for 30 min, and finally at 1400 r / min for 30 min to obtain a uniformly mixed, bubble-free cast slurry.

[0078] S22: The cast slurry is coated onto a PET film and then dried to obtain a cast raw material tape;

[0079] S23: Firing the cast raw material tape to obtain a ceramic substrate;

[0080] Specifically, after cutting, hot-pressing and stacking the cast raw material tape and removing the PET film, the heating rate is controlled at 0.5℃ / min, raised to 300℃ and held for 1 hour, then raised to 550℃ at a rate of 0.5℃ / min and held for 4 hours, and finally raised to 820℃ at a rate of 3℃ / min and held for 4 hours to obtain the desired ceramic substrate.

[0081] Table 1 summarizes the formulations and properties of the ceramic matrix xBaO-yCuO-zSiO2.

[0082] Table 1 Formulations and sintering conditions for ceramic matrix examples

[0083]

[0084] The formulations for the BCB oxide examples are shown in Table 2.

[0085] Table 2 Formulations and sintering conditions for BCB oxide examples

[0086]

[0087] The preparation method of Li2O-B2O3-SiO2-CaO-Al2O3 glass powder is as follows:

[0088] Using Li2CO3, H3BO3, SiO2, CaCO3, and Al2O3 as raw materials, the powder was weighed and mixed according to either component 1 (33wt% Li2O, 45wt% B2O3, 15wt% SiO2, 3wt% CaO, and 4wt% Al2O3) or component 2 (32wt% Li2O, 44wt% B2O3, 16wt% SiO2, 2wt% CaO, and 6wt% Al2O3). The powder, zirconium balls, and pure water were ball-milled at a mass ratio of 1:2:2 for 3 hours, then completely dried at 130℃. After ball milling and drying, the powder was melted at 1100℃ for 2 hours, then quenched in pure water, crushed into fine powder, and passed through a 300-mesh sieve to obtain Li2O-B2O3-SiO2-CaO-Al2O3 glass powder for later use.

[0089] Table 3 summarizes the examples and formulations of low dielectric constant low-temperature co-fired ceramic material systems.

[0090] Table 3. Formulations of Low-Temperature Co-fired Ceramic Material Systems (Examples)

[0091]

[0092] Example 1

[0093] A method for preparing a low-dielectric-constant low-temperature co-fired ceramic material system is as follows:

[0094] (1) Prepare the raw materials BaCO3, CuO and SiO2 according to the ceramic matrix ratio a in Table 1. Ball mill the powder, zirconium balls and pure water at a mass ratio of 1:2:2 for 4 hours. Then dry the powder completely at 130°C. After pre-firing the powder at 950°C for 3 hours, sieve it through a 300-mesh sieve to obtain the ceramic matrix powder for later use.

[0095] (2) The ceramic matrix powder and the sintering aid powder were mixed according to the mass ratio of 93wt% of ceramic matrix prepared by formula a and 7wt% of glass powder prepared by component 1. The mixture was ball-milled at a mass ratio of powder:zirconia balls:pure water of 1:2:2 for 4 hours. The mixture was then completely dried at 130°C and sieved through a 200-mesh sieve to obtain the low-temperature co-fired ceramic formula powder for later use.

[0096] (3) Add the obtained formula powder to PVA binder, granulate it, press it into cylindrical and cuboid green bodies, and then in an air atmosphere, first raise the temperature to 550°C at a heating rate of 1°C / min, hold it for 4 hours to remove the binder, and then raise the temperature to 800°C at a heating rate of 3°C / min, hold it for 4 hours to obtain the low-temperature co-fired ceramic block.

[0097] Example 2

[0098] A method for preparing a low-dielectric-constant low-temperature co-fired ceramic material system is as follows:

[0099] (1) Prepare the raw materials BaCO3, CuO and SiO2 according to the ceramic matrix ratio a in Table 1. Ball mill the powder, zirconium balls and pure water at a mass ratio of 1:2:2 for 4 hours. Then dry the powder completely at 130°C. After pre-firing the powder at 950°C for 3 hours, sieve it through a 300-mesh sieve to obtain the ceramic matrix powder for later use.

[0100] (2) According to the BCB oxide ratio g described in Table 2, the raw materials BaCO3, CuO and B2O3 were prepared and ball-milled at a mass ratio of powder:zirconium balls:pure water of 1:2:2 for 4 hours. Then, the powder was completely dried at 130℃. The powder was first kept at 400℃ for 1 hour and then kept at 600℃ for 2 hours for pre-calcination treatment. The heating rate was controlled at 5℃ / min. Then, the powder was passed through a 300-mesh sieve to obtain BCB oxide powder for later use.

[0101] (3) The ceramic matrix powder and the sintering aid powder were mixed according to the mass ratio of 95wt% of ceramic matrix prepared by formula a and 5wt% of BCB oxide prepared by formula g. The mixture was ball-milled at a mass ratio of powder:zirconia balls:pure water of 1:2:2 for 4 hours. The mixture was then completely dried at 130°C and sieved through a 200-mesh sieve to obtain the low-temperature co-fired ceramic formula powder for later use.

[0102] (4) The obtained formula powder is added to PVA binder, granulated, and pressed into cylindrical and cuboid green bodies. Then, in an air atmosphere, the temperature is first raised to 550°C at a rate of 1°C / min and held for 4 hours. Then, the temperature is raised to 950°C at a rate of 3°C / min and held for 4 hours to obtain the low-temperature co-fired ceramic block.

[0103] Example 3

[0104] A method for preparing a low-dielectric-constant low-temperature co-fired ceramic material system is as follows:

[0105] (1) Prepare the raw materials BaCO3, CuO and SiO2 according to the ceramic matrix ratio a in Table 1. Ball mill the powder, zirconium balls and pure water at a mass ratio of 1:2:2 for 4 hours. Then dry the powder completely at 130°C. After pre-firing the powder at 950°C for 3 hours, sieve it through a 300-mesh sieve to obtain the ceramic matrix powder for later use.

[0106] (2) The ceramic matrix powder and the sintering aid powder were mixed according to the mass ratio of 96 wt% ceramic matrix prepared by formula a, 3 wt% glass powder prepared by component 2 and 1 wt% LiF. The mixture was ball-milled at a mass ratio of powder:zirconia ball:pure water of 1:2:2 for 4 hours. The mixture was then completely dried at 130°C and sieved through a 200-mesh sieve to obtain the low-temperature co-fired ceramic formula powder for later use.

[0107] (3) The obtained formula powder is added to PVA binder, granulated, and pressed into cylindrical and cuboid green bodies. Then, in an air atmosphere, the temperature is first raised to 550°C at a rate of 1°C / min and held for 4 hours. Then, the temperature is raised to 820°C at a rate of 3°C / min and held for 4 hours to obtain the low-temperature co-fired ceramic block.

[0108] Example 4

[0109] A method for preparing a low-dielectric-constant low-temperature co-fired ceramic material system is as follows:

[0110] (1) Prepare the raw materials BaCO3, CuO and SiO2 according to the ceramic matrix ratio a in Table 1. Ball mill the powder, zirconium balls and pure water at a mass ratio of 1:2:2 for 4 hours. Then dry the powder completely at 130°C. After pre-firing the powder at 950°C for 3 hours, sieve it through a 300-mesh sieve to obtain the ceramic matrix powder for later use.

[0111] (2) According to the BCB oxide ratio h in Table 2, the raw materials BaCO3, CuO and B2O3 were prepared and ball-milled at a mass ratio of powder:zirconium balls:pure water of 1:2:2 for 4 hours. Then, the powder was completely dried at 130°C. The powder was first kept at 400°C for 1 hour and then kept at 600°C for 2 hours for pre-calcination treatment. The heating rate was controlled at 5°C / min. Then, the powder was passed through a 300-mesh sieve to obtain BCB oxide powder for later use.

[0112] (3) The ceramic matrix powder and the sintering aid powder were mixed according to the mass ratio of 99 wt% of the ceramic matrix prepared by formula a and 1 wt% of the BCB oxide prepared by formula h. The mixture was ball-milled at a mass ratio of powder:zirconia balls:pure water of 1:2:2 for 4 hours. The mixture was then completely dried at 130°C and sieved through a 200-mesh sieve to obtain the low-temperature co-fired ceramic formula powder for later use.

[0113] (4) The obtained formula powder is added to PVA binder, granulated, and pressed into cylindrical and cuboid green bodies. Then, in an air atmosphere, the temperature is first raised to 550°C at a rate of 1°C / min and held for 4 hours. Then, the temperature is raised to 1000°C at a rate of 3°C / min and held for 4 hours to obtain the low-temperature co-fired ceramic block.

[0114] Example 5

[0115] A method for preparing a low-dielectric-constant low-temperature co-fired ceramic material system is as follows:

[0116] (1) Prepare the raw materials BaCO3, CuO and SiO2 according to the ceramic matrix ratio b in Table 1. Ball mill the powder, zirconium balls and pure water at a mass ratio of 1:2:2 for 4 hours. Then dry the powder completely at 130°C. After pre-firing the powder at 950°C for 3 hours, sieve it through a 300-mesh sieve to obtain the ceramic matrix powder for later use.

[0117] (2) The ceramic matrix powder and the sintering aid powder were mixed according to the mass ratio of 97wt% ceramic matrix prepared by formula b, 1.5wt% glass powder prepared by component 1, and 1.5wt% LiF. The mixture was ball-milled at a mass ratio of powder:zirconia balls:pure water of 1:2:2 for 4 hours. The mixture was then completely dried at 130℃ and sieved through a 200-mesh sieve to obtain the low-temperature co-fired ceramic formula powder for later use.

[0118] (3) The obtained formula powder is added to PVA binder, granulated, and pressed into cylindrical and cuboid green bodies. Then, in an air atmosphere, the temperature is first raised to 550°C at a rate of 1°C / min and held for 4 hours. Then, the temperature is raised to 830°C at a rate of 3°C / min and held for 4 hours to obtain the low-temperature co-fired ceramic block.

[0119] Example 6

[0120] A method for preparing a low-dielectric-constant low-temperature co-fired ceramic material system is as follows:

[0121] (1) Prepare the raw materials BaCO3, CuO and SiO2 according to the ceramic matrix ratio c in Table 1. Ball mill the powder, zirconium balls and pure water at a mass ratio of 1:2:2 for 4 hours. Then dry the powder completely at 130°C. After pre-firing the powder at 950°C for 3 hours, sieve it through a 300-mesh sieve to obtain the ceramic matrix powder for later use.

[0122] (2) According to the BCB oxide ratio g described in Table 2, the raw materials BaCO3, CuO and B2O3 were prepared and ball-milled at a mass ratio of powder:zirconium balls:pure water of 1:2:2 for 4 hours. Then, the powder was completely dried at 130℃. The powder was first kept at 400℃ for 1 hour and then kept at 600℃ for 2 hours for pre-calcination treatment. The heating rate was controlled at 5℃ / min. Then, the powder was passed through a 300-mesh sieve to obtain BCB oxide powder for later use.

[0123] (3) The ceramic matrix powder and the sintering aid powder were mixed according to the mass ratio of 97 wt% of ceramic matrix prepared by formula c, 2 wt% of BCB oxide prepared by formula g, and 1 wt% of glass powder prepared by component 1. The mixture was ball-milled at a mass ratio of powder:zirconia balls:pure water of 1:2:2 for 4 hours. The mixture was then completely dried at 130°C and sieved through a 200-mesh sieve to obtain the low-temperature co-fired ceramic formula powder for later use.

[0124] (4) The obtained formula powder is added to PVA binder, granulated, and pressed into cylindrical and cuboid green bodies. Then, in an air atmosphere, the temperature is first raised to 550°C at a rate of 1°C / min and held for 4 hours. Then, the temperature is raised to 910°C at a rate of 3°C / min and held for 4 hours to obtain the low-temperature co-fired ceramic block.

[0125] Example 7

[0126] A method for preparing a low-dielectric-constant low-temperature co-fired ceramic material system is as follows:

[0127] (1) Prepare the raw materials BaCO3, CuO and SiO2 according to the ceramic matrix ratio d in Table 1. Ball mill the powder, zirconium balls and pure water at a mass ratio of 1:2:2 for 4 hours. Then dry the powder completely at 130°C. After pre-firing the powder at 950°C for 3 hours, sieve it through a 300-mesh sieve to obtain the ceramic matrix powder for later use.

[0128] (2) According to the BCB oxide ratio g described in Table 2, the raw materials BaCO3, CuO and B2O3 were prepared and ball-milled at a mass ratio of powder:zirconium balls:pure water of 1:2:2 for 4 hours. Then, the powder was completely dried at 130℃. The powder was then pre-calcined at 400℃ for 1 hour and then at 600℃ for 2 hours with a heating rate of 5℃ / min. The powder was then passed through a 300-mesh sieve to obtain BCB oxide powder for later use.

[0129] (3) The ceramic matrix powder and the sintering aid powder were mixed according to the mass ratio of 97wt% of ceramic matrix prepared by formula d, 2wt% of BCB oxide prepared by formula g, and 1wt% of glass powder prepared by component 2. The mixture was ball-milled at a mass ratio of powder:zirconium ball:pure water of 1:2:2 for 4 hours. The mixture was then completely dried at 130°C and sieved through a 200-mesh sieve to obtain the low-temperature co-fired ceramic formula powder for later use.

[0130] (4) The obtained formula powder is added to PVA binder, granulated, and pressed into cylindrical and cuboid green bodies. Then, in an air atmosphere, the temperature is first raised to 550°C at a rate of 1°C / min and held for 4 hours. Then, the temperature is raised to 890°C at a rate of 3°C / min and held for 4 hours to obtain the low-temperature co-fired ceramic block.

[0131] Example 8

[0132] A method for preparing a low-dielectric-constant low-temperature co-fired ceramic material system is as follows:

[0133] (1) Prepare the raw materials BaCO3, CuO and SiO2 according to the ceramic matrix ratio e in Table 1. Ball mill the powder, zirconium balls and pure water at a mass ratio of 1:2:2 for 4 hours. Then dry the powder completely at 130°C. After pre-firing the powder at 950°C for 3 hours, sieve it through a 300-mesh sieve to obtain the ceramic matrix powder for later use.

[0134] (2) According to the BCB oxide ratio f in Table 2, the raw materials BaCO3, CuO and B2O3 were mixed and ball-milled at a mass ratio of powder:zirconium balls:pure water of 1:2:2 for 4 hours. Then, the powder was completely dried at 130°C. The powder was first kept at 400°C for 1 hour and then kept at 600°C for 2 hours for pre-calcination treatment. The heating rate was controlled at 5°C / min. Then, the powder was passed through a 300-mesh sieve to obtain BCB oxide powder for later use.

[0135] (3) The ceramic matrix powder and the sintering aid powder were mixed according to the mass ratio of 95 wt% of ceramic matrix prepared by formula e, 4 wt% of BCB oxide prepared by formula f, and 1 wt% of glass powder prepared by component 1. The mixture was ball-milled at a mass ratio of powder:zirconium ball:pure water of 1:2:2 for 4 hours. The mixture was then completely dried at 130°C and sieved through a 200-mesh sieve to obtain the low-temperature co-fired ceramic formula powder for later use.

[0136] (4) The obtained formula powder is added to PVA binder, granulated, and pressed into cylindrical and cuboid green bodies. Then, in an air atmosphere, the temperature is first raised to 550°C at a rate of 1°C / min and held for 4 hours. Then, the temperature is raised to 900°C at a rate of 3°C / min and held for 4 hours to obtain the low-temperature co-fired ceramic block.

[0137] Performance testing

[0138] The dielectric properties, thermal properties, and mechanical properties of the above embodiments were tested, and the test results are summarized in Table 4. Specifically, a closed-cavity resonator was used to test the microwave dielectric properties of the ceramic block, and a delta temperature chamber was used to test the temperature coefficient of the resonant frequency of the block from 25℃ to 85℃. A thermal expansion coefficient tester was used to collect the thermal expansion coefficient of cylindrical or cuboid samples from room temperature to 400℃. A three-point bending tester was used to test the bending strength of the standard sample.

[0139] Ag co-fired compatibility tests were conducted on the above embodiments. Low-temperature co-fired ceramic material powder was mixed with pure silver powder, pressed into sheets, and held at the sintering temperature for 2 hours. XRD and EDS tests were then performed. (See attached figures.) Figure 1 For example, Ag did not react with the main crystalline phase of the ceramic.

[0140] Table 4 Performance test results for each embodiment The above embodiments illustrate that by controlling the contents of x, y, and z in the ceramic matrix xBaO-yCuO-zSiO2, it is possible to achieve a matrix containing BaCuSi4O. 10 The formation of the composite main crystalline phases of BaCuSi2O6 and BaCu2Si2O7 can regulate the dielectric constant and CTE of the material system. Furthermore, by adding single and combined sintering aids in different proportions, dense ceramic samples can be obtained at appropriate sintering temperatures, and the relevant properties also meet the LTCC technical specifications.

[0141] Furthermore, Cu co-firing tests were added for Examples 2 and 4, see [link to relevant documentation]. Figure 2 The prepared copper electrode slurry was coated onto the surface of the low-temperature co-fired ceramic material powder, and sintered at 950°C for 2 hours under a protective atmosphere. SEM and EDS tests were performed, and it was found that the slurry flowed smoothly on the sample surface. SEM showed that a dense copper film was formed on the surface, and EDS determined that the low-temperature co-fired ceramic material powder was compatible with Cu co-firing.

[0142] Using the formulation of Example 3 as an example, a method for preparing a ceramic substrate based on the above-described low-dielectric-constant low-temperature co-fired ceramic material system is described:

[0143] (1) Ethanol and methyl ethyl ketone were used as solvents, and fish oil, polyvinyl butyral, polyethylene glycol and butyl benzyl phthalate were used as dispersants, binders and plasticizers respectively. According to the mass ratio of 48 wt% low-temperature co-fired ceramic powder (Example 3), 43 wt% solvent, 4 wt% plasticizer, 4 wt% binder and 1 wt% dispersant, the organic matter and low-temperature co-fired ceramic powder were mixed in a high-speed mixer. The high-speed mixer was set to first use 1000 r / min for 30 min, then use 1200 r / min for 30 min, and finally use 1400 r / min for 30 min to obtain a uniformly mixed and bubble-free cast slurry.

[0144] (2) The obtained casting slurry is cast onto a PET film and then dried naturally to obtain a raw material tape. The obtained raw material tape is cut, hot-pressed and laminated, and the PET film is removed. The heating rate is controlled at 0.5℃ / min, raised to 300℃ and held for 1 hour, then raised to 550℃ at a rate of 0.5℃ / min and held for 4 hours, and finally raised to 820℃ at a rate of 3℃ / min and held for 4 hours to obtain the desired ceramic substrate.

[0145] See Figure 3 and Figure 4 In the example, after the raw material strip is cut and hot-pressed, the surface is smooth and uniform. After further sintering, the shrinkage is uniform and the morphology is dense.

[0146] The dielectric properties of the obtained ceramic substrate were tested using the split resonant cavity method. The dielectric constant was measured to be 5.3 and the dielectric loss to be 0.0008, which are close to the properties of the bulk ceramic tested by the closed cavity method.

[0147] The present invention provides a detailed description of a low-temperature co-fired ceramic material system with a low dielectric constant and its preparation method. The low-temperature co-fired ceramic material obtained by the present invention has an adjustable dielectric constant of 5 to 8 and a dielectric loss of <10. -3 The coefficient of thermal expansion is 0.5 to 5 ppm / ℃ from room temperature to 400℃, which meets the thermal matching requirements of semiconductors such as Si. At the same time, the three-point bending strength is 70 to 120 MPa. The material is compatible with Ag and Cu electrodes and is suitable for casting process. It can be used as a substrate and dielectric material in 5G millimeter wave passive components and modules.

[0148] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A low-dielectric-constant low-temperature co-fired ceramic material system, characterized in that, The composition of the low dielectric constant low-temperature co-fired ceramic material system, by mass percentage, is as follows: The ceramic matrix is ​​93-99 wt%; the sintering aid is 1-7 wt%. The compositional formula of the ceramic matrix is ​​xBaO-yCuO-zSiO2, wherein x in xBaO-yCuO-zSiO2 ranges from 32 to 44 wt%, y ranges from 16 to 30 wt%, and z ranges from 30 to 52 wt%; by changing the contents of x, y, and z, a matrix containing BaCuSi4O2 can be achieved. 10 The formation of the composite main crystalline phases of BaCuSi2O6 and BaCu2Si2O7; The sintering aid includes at least one of Li2O-B2O3-SiO2-CaO-Al2O3 glass powder, LiF, and BaO-CuO-B2O3 oxide; By mass percentage, the Li2O-B2O3-SiO2-CaO-Al2O3 glass powder comprises 32-33 wt% Li2O, 44-45 wt% B2O3, 15-16 wt% SiO2, 2-3 wt% CaO, and 4-6 wt% Al2O3; the BaO-CuO-B2O3 oxide comprises 34-58 wt% BaO, 26-35 wt% CuO, and 13-31 wt% B2O3.

2. The low-dielectric-constant low-temperature co-fired ceramic material system according to claim 1, characterized in that, The microwave dielectric constant of the low-dielectric-constant low-temperature co-fired ceramic material system is 5~8, and the dielectric loss is <10. -3 The temperature coefficient of the resonant frequency is -8 to -37 ppm / ℃ at temperatures ranging from 25℃ to 85℃.

3. The low-dielectric-constant low-temperature co-fired ceramic material system according to claim 1, characterized in that, Within the range of room temperature to 400 °C, the coefficient of thermal expansion of the low dielectric constant low-temperature co-fired ceramic material system is 0.5~5 ppm / ℃.

4. The low-dielectric-constant low-temperature co-fired ceramic material system according to claim 1, characterized in that, The three-point flexural strength of the low dielectric constant low-temperature co-fired ceramic material system is 70~120 MPa.

5. The low dielectric constant low-temperature co-fired ceramic material system according to claim 1, characterized in that, The low dielectric constant low-temperature co-fired ceramic material system is compatible with Ag and Cu electrodes.

6. A method for preparing a low-dielectric-constant low-temperature co-fired ceramic material system according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1: Raw materials BaCO3, CuO, and SiO2 are prepared according to the composition formula of the ceramic matrix xBaO-yCuO-zSiO2, and then ball-milled and dried. After pre-firing at a set temperature and holding for a set time, the ceramic matrix is ​​obtained by sieving. A sintering aid is selected. In S1, the set temperature is 900℃~1000℃, and the set time is 3h. During the pre-firing process, the temperature is increased and decreased at a rate of 2~4℃ / min. S2: The low-temperature co-fired ceramic material powder is obtained by mixing the ceramic matrix and sintering aid according to the composition of the low dielectric constant low-temperature co-fired ceramic material system, followed by ball milling, drying and sieving. S3: The low-temperature co-fired ceramic material system powder is combined with PVA binder, granulated, and then pressed into a molded product. After obtaining the molded product, it is heated to a first set temperature at a first heating rate and held at that temperature for a first set time to remove the binder. Then, it is heated to a second set temperature at a second heating rate and sintered to obtain a low-dielectric-constant low-temperature co-fired ceramic. In S3, the first heating rate is 1℃ / min, the first set temperature is 550℃, and the first set time is 4h. The second heating rate is 2~4℃ / min, and the second set temperature is 800℃~1000℃.

7. The application of a low dielectric constant low-temperature co-fired ceramic material system according to any one of claims 1 to 5, characterized in that, It is used in the preparation of casting slurry, casting raw material tape and ceramic substrate.

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