Phosphate-based low dielectric constant ltcc material and preparation method thereof
By preparing phosphate-based low-dielectric LTCC materials with the chemical formula Na2O-AO-MgO-xP2O5, the problems of reducing costs and sintering temperature were solved, achieving stability in low dielectric constant and dielectric loss, making them suitable for the transmission of high-frequency communication microwave signals.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING INST OF TECH
- Filing Date
- 2024-10-23
- Publication Date
- 2026-07-24
AI Technical Summary
Existing technologies struggle to reduce the cost of phosphate-based low dielectric constants and dielectric losses without sacrificing performance, and traditional solid-phase synthesis suffers from the problem of a second phase.
Phosphate-based low dielectric LTCC materials with the chemical expression Na2O-AO-MgO-xP2O5 are used to prepare LTCC ceramic powder by hydrothermal method or solid-state sintering method, and the sintering temperature is reduced to below 900℃ by combining ball milling, pressing and sintering processes.
A low-cost, low-dielectric-constant, and low-dielectric-loss phosphate-based low-dielectric LTCC material has been developed, which is suitable for stable transmission of high-frequency communication microwave signals and can be used as an LTCC microwave substrate and dielectric antenna. Moreover, the fabrication process is environmentally friendly and stable.
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Figure CN119528561B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of microwave dielectric ceramics, and particularly relates to a phosphate-based low dielectric LTCC material and its preparation method. Background Technology
[0002] Low-temperature co-fired ceramics (LTCC), as a high-performance material, have shown broad application potential in the modern electronics industry. Their low dielectric constant, low loss, high thermal conductivity, and good thermal expansion coefficient matching meet the demands of high-frequency, high-speed, and highly integrated electronic components such as those used in 5G and the Internet of Things. With increasing demands for miniaturization, high performance, and reliability, LTCC ceramics play a crucial role in fields such as communications, automotive electronics, aerospace, and medicine, for example, in the manufacture of key components like filters, couplers, automotive electronic control modules, and cardiac pacemakers. In the future, with continuous technological advancements and market development, the application prospects of LTCC ceramics will be even broader.
[0003] Phosphate microwave dielectric ceramics are a class of ceramic materials with excellent microwave dielectric properties. They typically possess low cost, low sintering temperature, low dielectric constant, and low dielectric loss, making them ideal candidate materials in the field of low-temperature co-fired ceramics (LTCC) technology, providing a solid material foundation for the miniaturization and integration of high-frequency circuits. As 5G technology moves from theory to practical application, reducing costs without sacrificing performance has become crucial. Therefore, exploring novel phosphate systems and optimizing materials and preparation processes are essential for promoting the development of communication technology and upgrading the electronic information industry. This invention discloses a phosphate-based low-dielectric LTCC material and its preparation method. This compound has a ceramicization temperature below 950℃ and low dielectric loss, making it highly suitable for use as a microwave dielectric substrate. Summary of the Invention
[0004] The purpose of this invention is to provide a phosphate-based low-dielectric LTCC material and its preparation method, wherein the main crystalline phase of the material is Na2AMg(PO4)2 ( A =Sr, Ca or Sr 1-y Ca y It has advantages such as low cost, low sintering temperature, low dielectric constant, low dielectric loss, and stable preparation process.
[0005] To address the problems of existing technologies, this invention provides a phosphate-based low-dielectric LTCC material, whose chemical formula is Na₂O- A O-MgO- x P2O5, in which A =Sr, Ca or Sr 1-y Ca y , 1.0≤ x ≤1.2, 0< y≤0.2.
[0006] The present invention also provides a method for preparing the above-mentioned phosphate-based low-dielectric LTCC material, comprising the following steps:
[0007] Step 1: Synthesis of LTCC ceramic powder: LTCC ceramic powder is prepared by using high-purity powders of Na2CO3, SrCO3, CaCO3, Mg(OH)2 and NH4H2PO4 as raw materials through hydrothermal method or solid-state sintering method.
[0008] Step 2, ball milling: Transfer the synthesized LTCC ceramic powder to a nylon ball mill jar, add the ball milling media and grinding balls, and place it in a planetary ball mill for wet milling. The grinding balls are made of zirconium dioxide. The mass ratio of the mixture, grinding balls and ball milling media is 1:5:1.2. The ball milling time is 8~12 hours and the ball mill speed is 250~350 rpm.
[0009] Step 3, pressing and molding: After drying the ball mill slurry, add 5-8 wt% of binder, mix, sieve, and granulate; press into a green body on a unidirectional press with a pressure of 100-150 MPa;
[0010] Step 4: Sintering into ceramic: Place the pressed blank in a box-type resistance furnace and heat it slowly to 500℃ and hold for 2 hours, then heat it to 650℃ and hold for 2 hours, then heat it to 750~900℃ and hold for 4~8 hours, and finally cool it with the furnace to obtain phosphate-based low dielectric LTCC material.
[0011] Preferably, the chemical formula of the main crystalline phase of this LTCC material is Na2AMg(PO4)2 ( A =Sr, Ca or Sr 1- y Ca y ).
[0012] Preferably, the Na2CO3, SrCO3, CaCO3, Mg(OH)2 and NH4H2PO4 powders in step one have a particle size of 1~5μm and a purity of ≥99.5%.
[0013] Preferably, the specific method for preparing LTCC ceramic powder by hydrothermal method in step one is as follows: Na2CO3, SrCO3, CaCO3, Mg(OH)2, and NH4H2PO4 raw material powders are prepared according to the chemical formula Na2O- A O-MgO- x P2O5 ( A =Sr, Ca or Sr 1-y Ca y , 1.0≤ x ≤1.2, 0< y≤0.2) Weigh and mix the ingredients to form a mixed powder; dissolve the mixed powder in deionized water, then add anhydrous ethanol and surfactant to the mixed solution and stir to form a turbid liquid. Transfer the turbid liquid to a high-pressure reactor, gradually raise the temperature to 120~150℃ and react for 12~24h. Cool to room temperature, wash three times by centrifugation with deionized water and anhydrous ethanol, and dry at 90℃ for 4h to obtain LTCC ceramic powder.
[0014] Preferably, the specific method for preparing LTCC ceramic powder by solid-state sintering in step one is as follows: Na2CO3, SrCO3, CaCO3, Mg(OH)2, and NH4H2PO4 raw material powders are prepared according to the chemical formula Na2O- A O-MgO- x P2O5 ( A =Sr, Ca or Sr 1- y Ca y , 1.0≤ x ≤1.2, 0< y ≤0.2) Weigh and mix the ingredients to form a mixed powder; transfer the mixed powder to an alumina crucible, place it in a box-type resistance furnace and heat it to 600~700℃, keep it at that temperature for 4~6 hours and then cool it to room temperature.
[0015] Preferably, the milling medium is anhydrous ethanol or deionized water.
[0016] Preferably, the adhesive is a 5 wt% aqueous solution of polyvinyl alcohol.
[0017] Preferably, the mixed powder is dissolved in deionized water to prepare a mixed solution with a mass concentration of 10%; then anhydrous ethanol and a surfactant are added to the mixed solution, wherein the anhydrous ethanol accounts for 30% of the total volume of the mixed solution and the surfactant accounts for 10% of the total volume of the mixed solution.
[0018] Preferably, the surfactant is one of sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, and silane coupling agent.
[0019] The beneficial effects of this invention are as follows:
[0020] (1) This invention solves the problem of the presence of a second phase in phosphate ceramics in traditional solid-phase synthesis by using excess phosphorus. It can also significantly reduce the sintering temperature of phosphate-based low dielectric LTCC materials to below 900℃, and can be applied in the LTCC field.
[0021] (2) The sintering temperature of the phosphate-based low-dielectric LTCC material prepared by this invention is 750~900℃, the dielectric constant is 8.2~9.3, and Q... fWith a value of 41800~80310GHz, it can solve the time delay problem of microwave signals in high-frequency communication and improve the stability of microwave signal transmission. It is very suitable for use in LTCC microwave substrates, dielectric antennas and other systems.
[0022] (3) The phosphate-based low dielectric LTCC material provided by the present invention has a simple preparation process, low raw material cost, no environmental pollution, and good production process stability, making it suitable for large-scale industrial production. Attached Figure Description
[0023] Figure 1 This is the XRD pattern of the phosphate-based low dielectric LTCC material prepared in Example 1 of the present invention.
[0024] Figure 2 This is a SEM image of the phosphate-based low dielectric LTCC material prepared in Example 1 of the present invention. Detailed Implementation
[0025] The present invention will now be further described. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.
[0026] Table 1 shows the mixtures of five components. Phosphate-based low-dielectric LTCC materials were prepared using different process parameters, and their microwave dielectric properties were measured.
[0027] Table 1. Mixture powder of five components (mol%)
[0028]
[0029] Example 1
[0030] Step 1: Synthesis of LTCC Powder: Na₂CO₃, SrCO₃, CaCO₃, Mg(OH)₂, and NH₄H₂PO₄ raw material powders were weighed and mixed according to the composition formula in Table 1 to form a mixed powder. The mixed powder was dissolved in deionized water to prepare a mixed solution with a mass concentration of 10%. Subsequently, anhydrous ethanol and sodium dodecyl sulfate were added to the mixed solution and stirred to form a turbid liquid, wherein anhydrous ethanol accounted for 30% of the total volume of the mixed solution, and the surfactant accounted for 10% of the total volume of the mixed solution. The turbid liquid was transferred to a high-pressure reactor, and the temperature was gradually increased to 120℃ for 24 hours. After cooling to room temperature, the mixture was washed three times by centrifugation using deionized water and anhydrous ethanol, and then dried at 90℃ for 4 hours to obtain LTCC powder.
[0031] Step 2, ball milling: Transfer the synthesized LTCC ceramic powder to a nylon ball mill jar, add the ball milling media and grinding balls, and place it in a planetary ball mill for wet milling. The ball milling media is deionized water, the grinding balls are made of zirconium dioxide, and the mass ratio of the mixture, grinding balls and deionized water is 1:5:1.2. The ball milling time is 12 hours and the ball mill speed is 250 rpm.
[0032] Step 3, pressing and molding: After drying the ball mill slurry, add 8 wt% of its weight of binder, mix, sieve, and granulate; press into a green body on a unidirectional press with a pressure of 150 MPa;
[0033] Step 4: Sintering into ceramic: The pressed blank is placed in a box-type resistance furnace and heated slowly to 500°C and held for 2 hours, then heated to 650°C and held for 2 hours, then heated to 750°C and held for 8 hours, and finally cooled with the furnace to obtain phosphate-based low dielectric LTCC material.
[0034] The material obtained in this embodiment was subjected to performance testing, and the test results are shown in Table 2.
[0035] Table 2. Dielectric properties of different materials prepared using Example 1
[0036]
[0037] Example 2
[0038] Step 1: Synthesis of LTCC Powder: Na₂CO₃, SrCO₃, CaCO₃, Mg(OH)₂, and NH₄H₂PO₄ raw material powders were weighed and mixed according to the composition formula in Table 1 to form a mixed powder. The mixed powder was dissolved in deionized water to prepare a mixed solution with a mass concentration of 10%. Subsequently, anhydrous ethanol and sodium dodecyl sulfate were added to the mixed solution and stirred to form a turbid liquid, wherein anhydrous ethanol accounted for 30% of the total volume of the mixed solution, and the surfactant accounted for 10% of the total volume of the mixed solution. The turbid liquid was transferred to a high-pressure reactor, and the temperature was gradually increased to 150℃ and reacted for 12 hours. After cooling to room temperature, the mixture was washed three times by centrifugation using deionized water and anhydrous ethanol, and then dried at 90℃ for 4 hours to obtain LTCC powder.
[0039] Step 2, ball milling: Transfer the synthesized LTCC ceramic powder to a nylon ball mill jar, add the ball milling media and grinding balls, and place it in a planetary ball mill for wet milling. The ball milling media is anhydrous ethanol, and the grinding balls are made of zirconium dioxide. The mass ratio of the mixture, grinding balls and anhydrous ethanol is 1:5:1.2. The ball milling time is 8 hours and the ball mill speed is 350 rpm.
[0040] Step 3, pressing and molding: After drying the ball mill slurry, add 5 wt% of its weight of a 5 wt% polyvinyl alcohol aqueous solution, mix, sieve, and granulate; press into a green body on a unidirectional press with a pressure of 100 MPa;
[0041] Step 4: Sintering into ceramic: The pressed blank is placed in a box-type resistance furnace and heated slowly to 500°C and held for 2 hours, then heated to 650°C and held for 2 hours, then heated to 850°C and held for 4 hours, and finally cooled with the furnace to obtain phosphate-based low dielectric LTCC material.
[0042] The material obtained in this embodiment was subjected to performance testing, and the test results are shown in Table 3.
[0043] Table 3. Dielectric properties of different materials prepared using Example 2
[0044]
[0045] Example 3
[0046] Step 1: Synthesis of LTCC ceramic powder: Weigh and mix the raw material powders Na2CO3, SrCO3, CaCO3, Mg(OH)2 and NH4H2PO4 according to the composition formula in Table 1 to form a mixed powder. Transfer the mixed powder to an alumina crucible, place it in a box-type resistance furnace and heat it to 600℃. After holding it at that temperature for 6 hours, cool it to room temperature.
[0047] Step 2, ball milling: Transfer the synthesized LTCC ceramic powder to a nylon ball mill jar, add the ball milling media and grinding balls, and place it in a planetary ball mill for wet milling. The ball milling media is deionized water, the grinding balls are made of zirconium dioxide, and the mass ratio of the mixture, grinding balls and deionized water is 1:5:1.2. The ball milling time is 12 hours and the ball mill speed is 250 rpm.
[0048] Step 3, pressing and molding: After drying the ball mill slurry, add 8 wt% of its weight of binder, mix, sieve, and granulate; press into a green body on a unidirectional press with a pressure of 150 MPa;
[0049] Step 4: Sintering into ceramic: The pressed blank is placed in a box-type resistance furnace and heated slowly to 500°C and held for 2 hours, then heated to 650°C and held for 2 hours, then heated to 800°C and held for 7 hours, and finally cooled with the furnace to obtain phosphate-based low dielectric LTCC material.
[0050] The material obtained in this embodiment was subjected to performance testing, and the test results are shown in Table 4.
[0051] Table 4. Dielectric properties of different materials prepared using Example 3
[0052]
[0053] Example 4
[0054] Step 1: Synthesis of LTCC ceramic powder: Weigh and mix the raw material powders Na2CO3, SrCO3, CaCO3, Mg(OH)2 and NH4H2PO4 according to the composition formula in Table 1 to form a mixed powder. Transfer the mixed powder to an alumina crucible, place it in a box-type resistance furnace and heat it to 700℃. After holding it at this temperature for 4 hours, cool it to room temperature.
[0055] Step 2, ball milling: Transfer the synthesized LTCC ceramic powder to a nylon ball mill jar, add the ball milling media and grinding balls, and place it in a planetary ball mill for wet milling. The ball milling media is anhydrous ethanol, and the grinding balls are made of zirconium dioxide. The mass ratio of the mixture, grinding balls and anhydrous ethanol is 1:5:1.2. The ball milling time is 10 hours and the ball mill speed is 300 rpm.
[0056] Step 3, pressing and molding: After drying the ball mill slurry, add 7 wt% of its weight of a 5 wt% polyvinyl alcohol aqueous solution, mix, sieve, and granulate; press into a green body on a unidirectional press at a pressure of 120 MPa;
[0057] Step 4: Sintering into ceramic: The pressed blank is placed in a box-type resistance furnace and heated slowly to 500°C and held for 2 hours, then heated to 650°C and held for 2 hours, then heated to 900°C and held for 5 hours, and finally cooled with the furnace to obtain phosphate-based low dielectric LTCC material.
[0058] The material obtained in this embodiment was subjected to performance testing, and the test results are shown in Table 5.
[0059] Table 5. Dielectric properties of different materials prepared using Example 4
[0060]
[0061] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a phosphate-based low-dielectric LTCC material, characterized in that, The chemical formula for this LTCC material is Na₂O- A O-MgO- x P2O5, in which A =Sr, Ca or Sr 1-y Ca y 1.0 < x ≤1.2, 0< y ≤0.2; The preparation method of this phosphate-based low-dielectric LTCC material includes the following steps: Step 1: Synthesis of LTCC ceramic powder: LTCC ceramic powder is prepared by hydrothermal method using high-purity powders of Na2CO3, SrCO3, CaCO3, Mg(OH)2 and NH4H2PO4 as raw materials. Step 2, ball milling: Transfer the synthesized LTCC ceramic powder to a nylon ball mill jar, add the ball milling media and grinding balls, and place it in a planetary ball mill for wet milling. The grinding balls are made of zirconium dioxide. The mass ratio of the mixture, grinding balls and ball milling media is 1:5:1.
2. The ball milling time is 8~12 hours and the ball mill speed is 250~350 rpm. Step 3, pressing and molding: After drying the ball mill slurry, add 5-8 wt% of binder, mix, sieve, and granulate; press into a green body on a unidirectional press with a pressure of 100-150 MPa; Step 4: Sintering into ceramic: The pressed blank is placed in a box-type resistance furnace and heated slowly to 500°C and held for 2 hours, then heated to 650°C and held for 2 hours, then heated to 750°C and held for 8 hours, and finally cooled with the furnace to obtain phosphate-based low dielectric LTCC material.
2. The method for preparing a phosphate-based low-dielectric LTCC material according to claim 1, characterized in that, The chemical formula for the main crystalline phase of this LTCC material is Na₂AMg(PO₄)₂, in which... A =Sr, Ca or Sr 1-y Ca y .
3. The method for preparing a phosphate-based low-dielectric LTCC material according to claim 1, characterized in that, In step one, the particle size of Na2CO3, SrCO3, CaCO3, Mg(OH)2 and NH4H2PO4 powders is 1~5μm and the purity is ≥99.5%.
4. The method for preparing a phosphate-based low-dielectric LTCC material according to claim 1, characterized in that, The specific method for preparing LTCC ceramic powder by hydrothermal method in step one is as follows: Na2CO3, SrCO3, CaCO3, Mg(OH)2, and NH4H2PO4 raw material powders are prepared according to the chemical formula Na2O- A O-MgO- x P2O5, in which A =Sr, Ca or Sr 1-y Ca y 1.0 < x ≤1.2, 0< y ≤0.2, weigh and mix the ingredients to form a mixed powder; dissolve the mixed powder in deionized water, then add anhydrous ethanol and surfactant to the mixed solution and stir to form a turbid liquid. Transfer the turbid liquid to a high-pressure reactor, gradually raise the temperature to 120~150℃ and react for 12~24h. Cool to room temperature, wash three times by centrifugation using deionized water and anhydrous ethanol, and dry at 90℃ for 4h to obtain LTCC ceramic powder.
5. The method for preparing a phosphate-based low-dielectric LTCC material according to claim 1, characterized in that, The ball milling media is anhydrous ethanol or deionized water.
6. The method for preparing a phosphate-based low-dielectric LTCC material according to claim 1, characterized in that, The adhesive is a 5 wt% aqueous solution of polyvinyl alcohol.
7. The method for preparing a phosphate-based low-dielectric LTCC material according to claim 4, characterized in that, The mixed powder is dissolved in deionized water to prepare a mixed solution with a mass concentration of 10%; then anhydrous ethanol and a surfactant are added to the mixed solution, wherein the anhydrous ethanol accounts for 30% of the total volume of the mixed solution and the surfactant accounts for 10% of the total volume of the mixed solution.
8. The method for preparing a phosphate-based low-dielectric LTCC material according to claim 4, characterized in that, The surfactant is one of sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, or a silane coupling agent.