Methods for controlling the dielectric constant of ceramic substrate materials and their preparation methods

Abstract

This invention relates to the field of ceramic materials technology, specifically to a method for controlling the dielectric constant of a ceramic substrate material and its preparation method. The ceramic substrate material comprises at least two types of glass powder with different particle sizes, ceramic powder, and an organic carrier. The dielectric constant of the ceramic substrate material is controlled by adjusting the ratio of the glass powder with different particle sizes. The glass powder includes at least large-particle glass powder with a median particle size of 2.5-2.8 micrometers and small-particle glass powder with a median particle size of 1.1-1.4 micrometers. This invention controls the density of the sintered substrate by adjusting the particle size distribution of the glass powder in the LTCC slurry, thereby achieving a ceramic substrate material with an adjustable dielectric constant while maintaining relatively small fluctuations in mechanical properties. This has broad application prospects in fields such as electronic ceramic components and electronic device packaging.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic materials, and particularly to a method for regulating the dielectric constant and a preparation method of a ceramic substrate material. Background Art

[0002] Microwave dielectric ceramics are a new type of electronic material that acts as a dielectric material in the microwave (300 MHz < f < 300 GHz) frequency band and realizes various functions. Due to the characteristics of microwave such as short wavelength, high operating frequency, strong directivity, and strong penetration, it plays an important role in the 5G field. It can not only be used as resonators, filters, substrate materials, but also realize satellite communication, etc. Dielectric properties are the most important properties of microwave dielectric ceramics, including dielectric constant, dielectric loss, etc. In addition, good mechanical properties should also be satisfied. In practical applications, various performance indicators need to be comprehensively considered.

[0003] Low-temperature co-fired ceramics, i.e., LTCC technology, is a typical microwave dielectric ceramic technology and has become the mainstream way of electronic component integration, widely used in wireless communication in high-tech fields. By adjusting the LTCC material system, component ratio, adding additives, etc., ceramic substrate materials with different dielectric constants can be obtained to meet the requirements of different application scenarios.

[0004] In recent years, although many microwave dielectric materials with different dielectric constants have been developed, the main difficulty in developing new LTCC materials is that not only excellent dielectric properties need to be satisfied, but as a supporting material for carrying electronic components, it should also have excellent mechanical properties. Currently, for the same material system, by adjusting the component ratio and adding additives, while changing the dielectric constant of the ceramic substrate material, it will also have an adverse impact on its mechanical properties; and by methods such as surface modification, although small-range adjustment of the dielectric constant can be achieved, it will increase additional process flows and costs.

[0005] Therefore, it is necessary to provide an improved method for regulating the dielectric constant while maintaining its excellent mechanical properties to solve the above problems. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for regulating the dielectric constant and a preparation method of a ceramic substrate material, and a ceramic substrate material with adjustable dielectric constant is obtained by adjusting the particle size grading of glass powder in LTCC slurry, while maintaining excellent mechanical properties.

[0007] To achieve the above purpose, in the first aspect, the present invention provides a method for regulating the dielectric constant of a ceramic substrate material, and the composition of the ceramic substrate material includes: at least two kinds of glass powders with different particle sizes, ceramic powder, and an organic carrier; the dielectric constant of the ceramic substrate material is regulated by adjusting the ratio of the glass powders with different particle sizes.

[0008] This invention has found that the dielectric constant of glass powder can be controlled by simply adjusting the particle size distribution of the glass powder without the need for complex surface modification or other additives, while still ensuring its mechanical properties. This significantly simplifies the preparation process and reduces the preparation cost.

[0009] Furthermore, the dielectric constant of the ceramic substrate material at 5 GHz is adjustable within the range of 6.7-7.5, preferably within the range of 6.9-7.5; and the flexural strength fluctuates within the range of 210±10 MPa, preferably within the range of 210±5 MPa. The dielectric constant of this invention can be stably adjusted within the range of 6.7-7.5, meaning that the dielectric constant deviation of the ceramic substrate material obtained from multiple repetitions of glass powder with the same particle size distribution is ≤0.03, preferably ≤0.02.

[0010] The small range of variation in flexural strength indicates that, under the ceramic composition system of the present invention, although the variation in the particle size distribution of glass powder can result in different degrees of compactness of the substrate, it will not cause large-scale fluctuations in mechanical properties, which is something that the prior art has not yet been able to achieve.

[0011] Furthermore, the glass powder includes at least large-particle glass powder with a median particle size of 2.5-2.8 micrometers and small-particle glass powder with a median particle size of 1.1-1.4 micrometers. Preferably, the large-particle glass powder and the small-particle glass powder are the same type of glass powder. Using a blend of these two particle sizes minimizes fluctuations in flexural strength and causes varying degrees of change in the dielectric constant. When the particle size of the large-particle glass powder is too large, or the particle size of the small-particle glass powder is too small, although the dielectric constant can change, the flexural strength will also be significantly affected.

[0012] The mass ratio of large-particle glass powder to small-particle glass powder is 0:10-10:0, preferably 1:9-9:1.

[0013] In some specific embodiments, the glass powder includes large glass powder particles with a median particle size of 2.5 micrometers and small glass powder particles with a median particle size of 1.1 micrometers, with a mass ratio of 1:10, 1:8, 1:6, 1:5, 1:4, 1:2, 1:1, 1:0.8, 1:0.5, 1:0.2, 1:0.1, etc.

[0014] In some specific embodiments, the glass powder includes large glass powder particles with a median particle size of 2.6 micrometers and small glass powder particles with a median particle size of 1.1 micrometers, with a mass ratio of 1:10, 1:8, 1:6, 1:5, 1:4, 1:2, 1:1, 1:0.8, 1:0.5, 1:0.2, 1:0.1, etc.

[0015] In some specific embodiments, the glass powder includes large glass powder particles with a median particle size of 2.7 micrometers and small glass powder particles with a median particle size of 1.2 micrometers, with a mass ratio of 1:10, 1:8, 1:6, 1:5, 1:4, 1:2, 1:1, 1:0.8, 1:0.5, 1:0.2, 1:0.1, etc.

[0016] In some specific embodiments, the glass powder includes large glass powder particles with a median particle size of 2.8 micrometers and small glass powder particles with a median particle size of 1.3 micrometers, with a mass ratio of 1:10, 1:8, 1:6, 1:5, 1:4, 1:2, 1:1, 1:0.8, 1:0.5, 1:0.2, 1:0.1, etc.

[0017] In some specific embodiments, the glass powder includes large glass powder particles with a median particle size of 2.8 micrometers and small glass powder particles with a median particle size of 1.4 micrometers, with a mass ratio of 1:10, 1:8, 1:6, 1:5, 1:4, 1:2, 1:1, 1:0.8, 1:0.5, 1:0.2, 1:0.1, etc.

[0018] In some specific embodiments, the glass powder includes large glass powder particles with a median particle size of 2.5 micrometers and small glass powder particles with a median particle size of 1.4 micrometers, with a mass ratio of 1:10, 1:8, 1:6, 1:5, 1:4, 1:2, 1:1, 1:0.8, 1:0.5, 1:0.2, 1:0.1, etc.

[0019] In some specific embodiments, the glass powder includes large glass powder particles with a median particle size of 2.7 micrometers and small glass powder particles with a median particle size of 1.3 micrometers, with a mass ratio of 1:10, 1:8, 1:6, 1:5, 1:4, 1:2, 1:1, 1:0.8, 1:0.5, 1:0.2, 1:0.1, etc.

[0020] In some specific embodiments, the glass powder includes large glass powder particles with a median particle size of 2.6 micrometers and small glass powder particles with a median particle size of 1.4 micrometers, with a mass ratio of 1:10, 1:8, 1:6, 1:5, 1:4, 1:2, 1:1, 1:0.8, 1:0.5, 1:0.2, 1:0.1, etc.

[0021] This invention controls the density of the sintered substrate by grading glass powders of different particle sizes in a specific ratio. When glass powders of different sizes are graded, they form different dispersion and accumulation states within the green ceramic, resulting in varying degrees of density in the sintered substrate, i.e., different porosity ratios. This allows for the production of ceramic substrate materials with adjustable dielectric constants while maintaining relatively stable mechanical properties.

[0022] Furthermore, the glass powder is untreated glass powder, preferably untreated calcium boron lanthanum glass powder. This invention is based on research into untreated glass powder, meaning that surface treatment of the glass powder is unnecessary; the dielectric constant can be controlled simply by adjusting its particle size, thereby simplifying the preparation process and reducing costs.

[0023] Furthermore, the ceramic powder is selected from one or more of α-alumina, β-alumina and γ-alumina, and the particle size of the ceramic powder is 3.8-4.0 micrometers.

[0024] Furthermore, the ceramic substrate material comprises, by mass percentage: 15-40 wt% of at least two different particle sizes of glass powder, 30-50 wt% of ceramic powder, and 15-40 wt% of organic carrier.

[0025] Furthermore, the organic carrier includes a solvent, a binder, and a plasticizer.

[0026] The solvent includes at least two of ethyl acetate, butyl acetate, and isopropanol; the binder includes at least one of polymethyl methacrylate and polyvinyl butyral; and the plasticizer includes at least one of dibutyl phthalate and dioctyl phthalate.

[0027] Furthermore, the solvent accounts for 50-85% of the mass of the organic carrier, preferably 68-78%, more preferably 70-75%; the binder accounts for 10-25% of the mass of the organic carrier, preferably 12-20%, more preferably 15-18%; and the plasticizer accounts for 0.1-20% of the mass of the organic carrier, preferably 5-15%, more preferably 8-11%.

[0028] Furthermore, the ceramic substrate material is LTCC (Low Temperature Co-fired Ceramic).

[0029] Furthermore, the method for controlling the dielectric constant of the ceramic substrate material includes: (a) grading the particle size of two types of glass powder, wherein the median particle size of the large glass powder particles is 2.5-2.8 micrometers, and the median particle size of the small glass powder particles is 1.1-1.4 micrometers; (b) ball milling and mixing the graded glass powder, ceramic powder, and organic carrier to obtain a ceramic slurry; (c) casting the ceramic slurry to obtain a green ceramic tape; and (d) cutting, hot-pressing, and sintering the green ceramic tape to obtain the ceramic substrate material.

[0030] Secondly, the present invention provides a ceramic substrate material with adjustable dielectric constant, obtained by any of the above-described control methods.

[0031] Thirdly, the present invention provides a method for preparing a ceramic substrate material with an adjustable dielectric constant, comprising:

[0032] Step 1: At least two different glass powders with different particle sizes are graded to obtain graded glass powder;

[0033] Step two: Mix the solvent, binder, and plasticizer, and stir to obtain an organic carrier;

[0034] Step 3: The graded glass powder, ceramic powder and organic carrier are ball-milled and mixed to obtain a ceramic slurry;

[0035] Step four: The ceramic slurry is subjected to vacuum degassing treatment and then cast to obtain LTCC green ceramic tape.

[0036] Step 5: The green ceramic strip is cut, stacked, hot-pressed, and sintered to obtain a ceramic substrate material.

[0037] Furthermore, the casting speed is 0.5 m / min to 1.0 m / min;

[0038] The ball milling mixing time is 36-60 hours;

[0039] The sintering temperature is 845-895℃, and the time is 18-36h.

[0040] Furthermore, the thickness of the LTCC green ceramic tape is 100-130 micrometers, and the number of LTCC green ceramic tape layers in the stack is 6-12.

[0041] The beneficial effects of this invention are as follows:

[0042] 1. The ceramic substrate material with adjustable dielectric constant provided by the present invention controls the density of the sintered substrate by adjusting the particle size distribution of glass powder in the ceramic slurry, thereby achieving a ceramic substrate material with adjustable dielectric constant under conditions of small fluctuation in mechanical properties. It has high production value and research significance, and has broad application prospects in the fields of electronic ceramic components and electronic device packaging.

[0043] 2. This invention has low production cost, simple process, and controllable reaction conditions, making it suitable for large-scale casting paste control, thereby obtaining ceramic substrate materials with adjustable dielectric constant in multiple batches.

[0044] 3. This invention, while ensuring that the ceramic powder and other LTCC slurry components are the same, adjusts the particle size distribution of the glass powder separately to avoid interference caused by multiple variables, and finally obtains ceramic substrate materials with different densities, thus achieving the purpose of adjustable dielectric constant. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram showing the distribution of glass powder in the green ceramic material provided by the present invention.

[0047] Figure 2 The XRD patterns are those of ceramic substrate materials obtained by sintering at 845°C in Examples 3, 4, 7, and 8 of this invention.

[0048] Figure 3 These are cross-sectional scanning electron microscope (SEM) images of ceramic substrate materials obtained by sintering at 845°C in Examples 3, 4, 7, and 8 of this invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0050] Example 1

[0051] This embodiment provides a method for preparing a ceramic substrate material with adjustable dielectric constant by grading the particle size of two types of glass powders, casting and sintering the slurry. The specific steps are as follows:

[0052] (1) Weigh D using an electronic balance. 50 40g of 2.5-micron glass powder and D 50 160g of 1.1-micron glass powder was added to a mixer and mixed at room temperature (25℃) for 10 minutes.

[0053] (2) Weigh 120g of ethyl acetate, 120g of butyl acetate, 55g of acrylic resin and 30g of dioctyl phthalate into a ball mill jar using an electronic balance, add ball milling media, and premix at room temperature (25°C) for 4 hours to obtain a uniformly dispersed organic carrier without undissolved particles.

[0054] (3) Weigh 240g of α-alumina powder and 200g of graded glass powder using an electronic balance and add them to a ball mill jar with a pre-prepared organic carrier. Ball mill at room temperature (25℃) for 36 hours.

[0055] (4) The ceramic slurry was subjected to vacuum degassing treatment, and then a 120-micron thick LTCC green ceramic tape was obtained by casting at a speed of 0.8 m / min.

[0056] (5) Cut the raw ceramic strip, stack it into 8 layers and hot press it to obtain a block. Place it in a sintering furnace and gradually heat it to 845℃. The total sintering time is 20h.

[0057] The tested ceramic substrate material has a dielectric constant of 7.221 at room temperature and a flexural strength of 210.6 MPa at 5 GHz.

[0058] Example 2

[0059] This embodiment provides a second method for preparing a ceramic substrate material with adjustable dielectric constant by grading the particle size of two types of glass powders, casting and sintering the slurry. The specific steps are as follows:

[0060] (1) Weigh D using an electronic balance. 50 90g of 2.5-micron glass powder and D 50 110g of 1.4-micron glass powder was added to a mixer and mixed at room temperature (25℃) for 10 minutes.

[0061] (2) Weigh 120g of ethyl acetate, 120g of butyl acetate, 55g of acrylic resin and 30g of dioctyl phthalate into a ball mill jar using an electronic balance, add ball milling media, and premix at room temperature (25°C) for 4 hours to obtain a uniformly dispersed organic carrier without undissolved particles.

[0062] (3) Weigh 240g of α-alumina powder and 200g of graded glass powder using an electronic balance and add them to a ball mill jar with a pre-prepared organic carrier. Ball mill at room temperature (25℃) for 36 hours.

[0063] (4) The ceramic slurry was subjected to vacuum degassing treatment, and then a 120-micron thick LTCC green ceramic tape was obtained by casting at a speed of 0.8 m / min.

[0064] (5) Cut the raw ceramic strip, stack it into 8 layers and hot press it to obtain a block. Place it in a sintering furnace and gradually heat it to 845℃. The total sintering time is 20h.

[0065] The tested ceramic substrate material has a dielectric constant of 7.018 at room temperature and a flexural strength of 206.3 MPa at 5 GHz.

[0066] Example 3

[0067] This embodiment provides a third method for preparing a ceramic substrate material with adjustable dielectric constant by using two types of glass powders of different sizes with particle size gradation, preparing a ceramic slurry, casting, and sintering it. The specific steps are as follows:

[0068] (1) Weigh D using an electronic balance. 50 120g of 2.8-micron glass powder and D 50 Add 80g of 1.1-micron glass powder to a mixer and mix at room temperature (25℃) for 10 minutes.

[0069] (2) Weigh 120g of ethyl acetate, 120g of butyl acetate, 55g of acrylic resin and 30g of dioctyl phthalate into a ball mill jar using an electronic balance, add ball milling media, and premix at room temperature (25°C) for 4 hours to obtain a uniformly dispersed organic carrier without undissolved particles.

[0070] (3) Weigh 240g of α-alumina powder and 200g of graded glass powder using an electronic balance and add them to a ball mill jar with a pre-prepared organic carrier. Ball mill at room temperature (25℃) for 36 hours.

[0071] (4) The ceramic slurry was subjected to vacuum degassing treatment, and then a 120-micron thick LTCC green ceramic tape was obtained by casting at a speed of 0.8 m / min.

[0072] (5) Cut the raw ceramic strip, stack it into 8 layers and hot press it to obtain a block. Place it in a sintering furnace and gradually heat it to 845℃. The total sintering time is 20h.

[0073] The tested ceramic substrate material has a dielectric constant of 7.508 at room temperature and a flexural strength of 209.8 MPa at 5 GHz.

[0074] Example 4

[0075] This embodiment provides a fourth method for preparing a ceramic substrate material with adjustable dielectric constant by using two types of glass powders of different sizes with particle size gradation, preparing a ceramic slurry, casting, and sintering it. The specific steps are as follows:

[0076] (1) Weigh D using an electronic balance. 50 160g of 2.8-micron glass powder and D 50 Add 40g of 1.4-micron glass powder to a mixer and mix at room temperature (25℃) for 10 minutes.

[0077] (2) Weigh 120g of ethyl acetate, 120g of butyl acetate, 55g of acrylic resin and 30g of dioctyl phthalate into a ball mill jar using an electronic balance, add ball milling media, and premix at room temperature (25°C) for 4 hours to obtain a uniformly dispersed organic carrier without undissolved particles.

[0078] (3) Weigh 240g of α-alumina powder and 200g of graded glass powder using an electronic balance and add them to a ball mill jar with a pre-prepared organic carrier. Ball mill at room temperature (25℃) for 36 hours.

[0079] (4) The ceramic slurry was subjected to vacuum degassing treatment, and then a 120-micron thick LTCC green ceramic tape was obtained by casting at a speed of 0.8 m / min.

[0080] (5) Cut the raw ceramic strip, stack it into 8 layers and hot press it to obtain a block. Place it in a sintering furnace and gradually heat it to 845℃. The total sintering time is 20h.

[0081] The tested ceramic substrate material has a dielectric constant of 6.912 at room temperature and a flexural strength of 205.2 MPa at 5 GHz.

[0082] Example 5

[0083] This embodiment provides a fifth method for preparing a ceramic substrate material with adjustable dielectric constant by using two types of glass powders of different sizes with particle size gradation, preparing a ceramic slurry, casting, and sintering it. The specific steps are as follows:

[0084] (1) Weigh D using an electronic balance. 50 40g of 2.6-micron glass powder and D 50 160g of 1.1-micron glass powder was added to a mixer and mixed at room temperature (25℃) for 10 minutes.

[0085] (2) Weigh 120g of ethyl acetate, 120g of butyl acetate, 55g of acrylic resin and 30g of dioctyl phthalate into a ball mill jar using an electronic balance, add ball milling media, and premix at room temperature (25°C) for 4 hours to obtain a uniformly dispersed organic carrier without undissolved particles.

[0086] (3) Weigh 240g of α-alumina powder and 200g of graded glass powder using an electronic balance and add them to a ball mill jar with a pre-prepared organic carrier. Ball mill at room temperature (25℃) for 36 hours.

[0087] (4) The ceramic slurry was subjected to vacuum degassing treatment, and then a 120-micron thick LTCC green ceramic tape was obtained by casting at a speed of 0.8 m / min.

[0088] (5) Cut the raw ceramic strip, stack it into 8 layers and hot press it to obtain a block. Place it in a sintering furnace and gradually heat it to 845℃. The total sintering time is 20h.

[0089] The tested ceramic substrate material has a dielectric constant of 7.205 at room temperature and a flexural strength of 211.4 MPa at 5 GHz.

[0090] Example 6

[0091] This embodiment provides a sixth method for preparing a ceramic substrate material with adjustable dielectric constant by using two types of glass powders of different sizes with particle size gradation, preparing a ceramic slurry, casting, and sintering it. The specific steps are as follows:

[0092] (1) Weigh D using an electronic balance. 50 160g of 2.5-micron glass powder and D 50 Add 40g of 1.3-micron glass powder to a mixer and mix at room temperature (25℃) for 10 minutes.

[0093] (2) Weigh 120g of ethyl acetate, 120g of butyl acetate, 55g of acrylic resin and 30g of dioctyl phthalate into a ball mill jar using an electronic balance, add ball milling media, and premix at room temperature (25°C) for 4 hours to obtain a uniformly dispersed organic carrier without undissolved particles.

[0094] (3) Weigh 240g of α-alumina powder and 200g of graded glass powder using an electronic balance and add them to a ball mill jar with a pre-prepared organic carrier. Ball mill at room temperature (25℃) for 36 hours.

[0095] (4) The ceramic slurry was subjected to vacuum degassing treatment, and then a 120-micron thick LTCC green ceramic tape was obtained by casting at a speed of 0.8 m / min.

[0096] (5) Cut the raw ceramic strip, stack it into 8 layers and hot press it to obtain a block. Place it in a sintering furnace and gradually heat it to 845℃. The total sintering time is 20h.

[0097] The tested ceramic substrate material has a dielectric constant of 6.903 at room temperature and a flexural strength of 207.7 MPa at 5 GHz.

[0098] Example 7

[0099] This embodiment provides a seventh method for preparing a ceramic substrate material with adjustable dielectric constant by using two types of glass powders of different sizes with particle size gradation, preparing a ceramic slurry, casting, and sintering it. The specific steps are as follows:

[0100] (1) Weigh 120g of ethyl acetate, 120g of butyl acetate, 55g of acrylic resin and 30g of dioctyl phthalate into a ball mill jar using an electronic balance, add ball milling media, and premix at room temperature (25℃) for 4 hours to obtain a uniformly dispersed organic carrier without undissolved particles.

[0101] (2) Weigh 240g of α-alumina powder and D using an electronic balance. 50 200g of 2.6-micron glass powder was added to a ball mill jar with a pre-prepared organic carrier and ball milled at room temperature (25℃) for 36 hours.

[0102] (3) The ceramic slurry was subjected to vacuum degassing treatment, and then a 120-micron thick LTCC green ceramic tape was obtained by casting at a speed of 0.8 m / min.

[0103] (4) Cut the raw ceramic strip, stack it into 8 layers and hot press it to obtain a block. Place it in a sintering furnace and gradually heat it to 845℃. The total sintering time is 20h.

[0104] The tested ceramic substrate material has a dielectric constant of 6.702 at room temperature and a flexural strength of 208.1 MPa at 5 GHz.

[0105] Example 8

[0106] This embodiment provides an eighth method for preparing a ceramic substrate material with adjustable dielectric constant by using two types of glass powders of different sizes with particle size gradation, preparing a ceramic slurry, casting, and sintering it. The specific steps are as follows:

[0107] (1) Weigh 120g of ethyl acetate, 120g of butyl acetate, 55g of acrylic resin and 30g of dioctyl phthalate into a ball mill jar using an electronic balance, add ball milling media, and premix at room temperature (25℃) for 4 hours to obtain a uniformly dispersed organic carrier without undissolved particles.

[0108] (2) Weigh 240g of α-alumina powder and D using an electronic balance. 50 200g of 1.3-micron glass powder was added to a ball mill jar with a pre-prepared organic carrier and ball milled at room temperature (25℃) for 36 hours.

[0109] (3) The ceramic slurry was subjected to vacuum degassing treatment, and then a 120-micron thick LTCC green ceramic tape was obtained by casting at a speed of 0.8 m / min.

[0110] (4) Cut the raw ceramic strip, stack it into 8 layers and hot press it to obtain a block. Place it in a sintering furnace and gradually heat it to 845℃. The total sintering time is 20h.

[0111] The tested ceramic substrate material has a dielectric constant of 7.306 at room temperature and a flexural strength of 212.4 MPa at 5 GHz.

[0112] Table 1 Particle size distribution of Examples 1-8

[0113] Example Large particle size (μm) Mass of large particle size (g) Small particle size (μm) Small particle size mass (g) Example 1 2.5 40 1.1 160 Example 2 2.5 90 1.4 110 Example 3 2.8 120 1.1 80 Example 4 2.8 160 1.4 40 Example 5 2.6 40 1.1 160 Example 6 2.5 160 1.3 40 Example 7 2.6 200 — 0 Example 8 — 0 1.3 200

[0114] Dielectric constant test and flexural strength test methods

[0115] Dielectric constant: The dielectric constant of the sample at 5 GHz was measured using a Keysight E5080B resonant cavity network analyzer with an accuracy within ±0.02.

[0116] Flexural strength: In accordance with the national standard GB / T 6569-2006 Test Method for Bending Strength of Fine Ceramics, a three-point bending specimen of sintered substrate was prepared and the three-point bending strength test was carried out on an E42 universal testing machine of MTS Corporation in the United States. The stress surface of the specimen was polished with diamond grinding. The test span was 15 mm and the indenter moving speed was 0.5 mm / min to obtain the maximum bending strength of the specimen.

[0117] Table 2. Dielectric constants and flexural strengths of Examples 1-8

[0118] Example Dielectric constant Flexural strength (MPa) Example 1 7.221 210.6 Example 2 7.018 206.3 Example 3 7.508 209.8 Example 4 6.912 205.2 Example 5 7.205 211.4 Example 6 6.903 207.7 Example 7 6.702 208.1 Example 8 7.306 212.4

[0119] As can be seen from Tables 1 and 2, within the particle size range defined by this invention, the ratio of the two particle sizes of glass powder has the main influence on the dielectric constant. For example, the ratios of the two particle sizes in Examples 1 and 5 are the same, resulting in the same dielectric constant; similarly, the ratios of the two particle sizes in Examples 4 and 6 are the same, resulting in the same dielectric constant. Furthermore, Examples 3 and 4 show that when the content of large-particle-size glass powder is much higher than that of small-particle-size glass powder (the ratio ≥ 4), the small-particle-size glass powder cannot completely fill the pores formed by the large-particle-size glass powder, resulting in higher porosity and a corresponding decrease in dielectric constant. However, the flexural strength does not decrease significantly, indicating that the two particle sizes of glass powder also have a certain synergistic effect on mechanical properties, offsetting the influence of porosity on strength. When the content of large-particle-size glass powder is close to that of small-particle-size glass powder (the ratio is approximately 1.3-1.6), the porosity is lower, and the dielectric constant is correspondingly higher.

[0120] Figure 1 This is a schematic diagram showing the distribution of glass powder in the green ceramic material provided by the present invention. a represents the distribution of large glass powder particles, alumina powder, and pores; b represents the distribution of small glass powder particles, alumina powder, and pores; and c represents the gradation of large and small glass powder particles and the distribution of alumina powder and pores.

[0121] Figure 2 The XRD patterns of ceramic substrate materials obtained by sintering at 845℃ in Examples 3, 4, 7, and 8 provided by this invention are shown. Comparison reveals that the crystallization peak positions and intensities of Examples 3, 4, 7, and 8 are similar and show no significant changes. This indicates that changing the particle size distribution of the glass powder did not generate a new crystalline phase, which is an important prerequisite for ensuring that the mechanical properties of the material system do not change significantly.

[0122] Figure 3 The cross-sectional scanning electron microscope images of the ceramic substrate materials obtained by sintering at 845°C in Examples 3, 4, 7, and 8 of this invention show that after graded sintering of glass powder of different particle sizes, the samples have pores of different sizes in the microstructure.

[0123] The organic binder is completely ablated during sintering, and the densification of the substrate is mainly achieved through the flow of the liquid glass phase and the rearrangement of ceramic particles. When glass powders of different particle sizes are graded, the glass powders form different dispersion and stacking states in the green ceramic, resulting in different densities of the sintered substrate, i.e., different porosity ratios.

[0124] Based on the empirical formula for calculating the dielectric constant of multiphase materials with randomly arranged constituent materials:

[0125] (1)

[0126] In the formula: Let be the dielectric constant of the material. Let be the electrical constant of component material 1. The dielectric constant of component material 2 is... This represents the volume fraction of component material 1. This represents the volume fraction of component material 2. It is known that the dielectric constant of a multiphase material is closely related to the dielectric constant and volume fraction of each component. From... Figure 1 It can be seen that the precipitated crystalline phases and their relative contents are basically consistent in the samples of different embodiments. The dielectric constant of alumina is 9.8, the dielectric constant of the main crystalline phase LaBO3 is 11.8, and the dielectric constant of air is about 1, which is much smaller than that of various crystalline phases and glass phases. Therefore, the porosity is the main influencing factor on the dielectric constant of the material at this time, and the sample with a higher porosity has a lower dielectric constant. Therefore, by distributing the particle size distribution of two types of glass powders in a certain proportion, the density of the sintered substrate can be controlled, thereby preparing a ceramic substrate material with an adjustable dielectric constant. At the same time, it can be seen from the flexural strength test results of this invention that under the particle size distribution defined by this invention, even if the porosity changes, the flexural strength will not decrease significantly.

[0127] To further verify the stability effect of the particle size distribution of the present invention, multiple sets of particle size distribution experiments were conducted, and the particle size distributions are shown in Table 3.

[0128] Table 3 Particle size distribution of Examples 9-20

[0129] Example Large particle size (μm) Mass of large particle size (g) Small particle size (μm) Small particle size mass (g) Example 9 2.8 40 1.1 160 Example 10 2.7 40 1.3 160 Example 11 2.8 90 1.1 110 Example 12 2.6 90 1.2 110 Example 13 2.5 120 1.4 80 Example 14 2.6 120 1.1 80 Example 15 2.8 160 1.1 40 Example 16 2.6 160 1.2 40 Example 17 2.8 180 1.1 20 Example 18 2.8 20 1.1 180 Example 19 3.0 160 1.1 40 Example 20 2.8 160 0.9 40

[0130] Table 4. Dielectric constants and flexural strengths of Examples 9-20

[0131] Example Dielectric constant Flexural strength (MPa) Example 9 7.219 210.2 Example 10 7.214 210.8 Example 11 7.031 206.9 Example 12 7.022 206.1 Example 13 7.493 209.4 Example 14 7.502 210.1 Example 15 6.918 205.8 Example 16 6.924 205.0 Example 17 6.781 208.9 Example 18 7.256 211.9 Example 19 6.325 178.8 Example 20 6.482 186.5

[0132] As shown in Table 4, when the mass ratio is the same, within the particle size range defined by this invention, the fluctuation of the dielectric constant is less than 0.02, and the flexural strength fluctuates within the range of 210±5 MPa. When the mass ratio changes, the dielectric constant changes, indicating that this invention can adjust the dielectric constant while maintaining strength through the particle size distribution of the glass powder. When the particle size is outside the limits defined by this invention, the dielectric constant changes significantly, and the flexural strength decreases significantly, making it difficult to meet higher application requirements.

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling the dielectric constant of a ceramic substrate material, characterized in that, The ceramic substrate material comprises at least two types of glass powder, ceramic powder, and organic carrier with different particle sizes; the dielectric constant of the ceramic substrate material is controlled by adjusting the ratio of the glass powder with different particle sizes. The glass powder includes at least large glass powder particles with a median particle size of 2.5-2.8 micrometers and small glass powder particles with a median particle size of 1.1-1.4 micrometers; The mass ratio of the large-particle glass powder to the small-particle glass powder is 1:9-9:1; The glass powder is calcium boron lanthanum glass powder; The ceramic powder is selected from one or more of α-alumina, β-alumina and γ-alumina, and the particle size of the ceramic powder is 3.8-4.0 micrometers.

2. The method for controlling the dielectric constant of a ceramic substrate material according to claim 1, characterized in that, The dielectric constant of the ceramic substrate material at 5 GHz is adjustable in the range of 6.7-7.5, and the flexural strength fluctuates within the range of 210±10 MPa.

3. The method for controlling the dielectric constant of the ceramic substrate material according to claim 1 or 2, characterized in that, The flexural strength of the ceramic substrate material fluctuates within the range of 210±5MPa.

4. The method for controlling the dielectric constant of the ceramic substrate material according to claim 3, characterized in that, The ceramic substrate material comprises, by mass percentage: 15-40 wt% of at least two different particle sizes of glass powder, 30-50 wt% of ceramic powder, and 15-40 wt% of organic carrier.

5. The method for controlling the dielectric constant of a ceramic substrate material according to claim 4, characterized in that, The organic carrier includes a solvent, a binder, and a plasticizer; The solvent includes at least two of ethyl acetate, butyl acetate, and isopropanol; the binder includes at least one of polymethyl methacrylate and polyvinyl butyral; and the plasticizer includes at least one of dibutyl phthalate and dioctyl phthalate.

6. The method for controlling the dielectric constant of a ceramic substrate material according to claim 5, characterized in that, The solvent accounts for 50-85% of the mass of the organic carrier; the binder accounts for 10-25% of the mass of the organic carrier; and the plasticizer accounts for 5-15% of the mass of the organic carrier. And / or, the ceramic substrate material is LTCC (Low Temperature Co-fired Ceramic).

7. A ceramic substrate material with adjustable dielectric constant, characterized in that, It is obtained by using the control method described in any one of claims 1-6.

8. A method for preparing a ceramic substrate material with adjustable dielectric constant as described in claim 7, characterized in that, include: Step 1: At least two different glass powders with different particle sizes are graded to obtain graded glass powder; Step two: Mix the solvent, binder, and plasticizer, and stir to obtain an organic carrier; Step 3: The graded glass powder, ceramic powder and organic carrier are ball-milled and mixed to obtain a ceramic slurry; Step 4: The ceramic slurry is subjected to vacuum degassing treatment and then cast to obtain LTCC green ceramic tape; Step 5: The green ceramic strip is cut, stacked, hot-pressed, and sintered to obtain a ceramic substrate material.

9. The method for preparing a ceramic substrate material with adjustable dielectric constant according to claim 8, characterized in that, The casting speed is 0.5 m / min to 1.0 m / min; The ball milling mixing time is 36-60 hours; The sintering temperature is 845-895℃, and the time is 18-36h; And / or, the thickness of the LTCC green ceramic tape is 100-130 micrometers, and the number of LTCC green ceramic tape layers in the stack is 6-12.

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