A negative capacitance temperature coefficient dielectric ceramic substrate material, its preparation method and application

Abstract

This invention discloses a dielectric ceramic substrate material with a negative capacitance temperature coefficient, its preparation method, and its application, relating to the field of functional ceramics technology. It comprises, by mass percentage, 76wt%~93.5wt% CaTiO. 3 2wt%~15.5wt% SrTiO 3 1wt%~8.5wt% MgTiO 3 The ceramic substrate material contains 1.5wt%~3.2wt% modifier and 2wt%~4.5wt% cooling agent. It possesses excellent flexural strength, good surface roughness, and bonding strength, making it suitable for fabricating miniaturized chip-type microwave monolayer ceramic capacitors with low dielectric loss. It exhibits a negative temperature coefficient of capacitance (-(1500±500)ppm / ℃, (-55~125)℃), which can compensate for capacitance drift caused by temperature changes and prevent signal distortion. Furthermore, it is flat, non-deformable, and has good rectangularity, exhibiting excellent surface properties.

Description

A dielectric ceramic substrate material with negative capacitance temperature coefficient, its preparation method and application Technical Field

[0001] This invention relates to the field of functional ceramics technology, specifically to a dielectric ceramic substrate material with a negative capacitance temperature coefficient, its preparation method, and its application. Background Technology

[0002] With the rapid development of 5G / 6G high-frequency communication, new energy vehicles, aerospace, and other fields, modern electronic information technology is accelerating towards miniaturization, portability, and multifunctionality. Electronic packaging materials need to balance high performance and high reliability to meet the requirements of high-frequency signal transmission in extreme environments (such as high frequency, high temperature, and low temperature), thermal shock resistance, and long-term stable operation. Ceramic substrates, with their excellent chemical stability, high thermal conductivity, low cost, and high mechanical strength, have become one of the core materials for electronic packaging, especially in the manufacture of single-layer ceramic capacitors, where they serve as a key dielectric material, directly affecting the frequency response and temperature stability of the capacitor.

[0003] Miniaturized chip microwave single-layer ceramic capacitors, due to their low residual inductance, high Q value, and high self-resonant frequency, have become an ideal choice for applications such as 5G communication base station filters, microwave modules, and satellite communication systems, leading to their explosive expansion in applications. Dielectric ceramic substrates with negative capacitance temperature coefficients (such as strontium titanate, barium titanate-based, and calcium titanate-based materials) can compensate for capacitance drift caused by temperature changes, suppress resonant frequency shifts and phase noise, and ensure high-frequency signal stability by adjusting their capacitance temperature coefficient (TCC). These substrates can be used in fields such as 5G base station filters and satellite communication modules.

[0004] Currently, industrial production uses tape casting to prepare piezoelectric and thermoelectric functional ceramics, which requires complex solvent systems and has a long process cycle. The produced ceramic substrates rely on high-temperature flattening to eliminate deformation or direct grinding and polishing to ensure flatness, thus limiting their applications. Furthermore, the surface condition of the ceramic substrate (such as flatness and roughness) also significantly impacts subsequent processes (such as electrode printing and co-firing). In addition, the fabrication process of miniaturized chip microwave single-layer ceramic capacitors requires repeated processing of the substrate through multiple steps (such as cleaning, drying, sputtering, and cutting), placing high demands on the strength of the ceramic substrate. However, GB / T 5596 specifies a static flexural strength of not less than 8000 N / cm² for capacitor ceramic materials. 2 That is, 80 MPa. However, current ceramic substrates still suffer from low strength and high dielectric loss. Summary of the Invention

[0005] Given that current ceramic substrates still suffer from low strength and high dielectric loss, the purpose of this invention is to provide a dielectric ceramic substrate material with a negative capacitance temperature coefficient, its preparation method, and its application. This ceramic substrate material has high strength, low dielectric loss, and good surface roughness and bonding strength, and can be used to prepare miniaturized chip microwave monolayer ceramic capacitors.

[0006] This invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a dielectric ceramic substrate material with a negative capacitance temperature coefficient, comprising, by mass percentage, 76wt%~93.5wt% CaTiO3, 2wt%~15.5wt% SrTiO3, 1wt%~8.5wt% MgTiO3, 1.5wt%~3.2wt% modifier, and 2wt%~4.5wt% cooling agent.

[0008] In this invention, CaTiO3, SrTiO3, and MgTiO3 are the main raw materials, all of which have a perovskite structure (or similar structure) and a general chemical formula of ABO3. They can be solid-solution-enabled and have a stable structure at high temperatures. The dielectric constant of CaTiO3 is 170, and its temperature coefficient is -2300ppm / ℃ (-60~20℃) and -1500ppm / ℃ (20~80℃); the dielectric constant of SrTiO3 is 270, and its temperature coefficient is -3000ppm / ℃ (20~80℃); the dielectric constant of MgTiO3 is 20, and its temperature coefficient is +200ppm / ℃ (20~80℃). Using CaTiO3 as the main component, combined with SrTiO3 and MgTiO3, the dielectric constant and capacitance temperature coefficient of the ceramic substrate material can be adjusted to achieve a dielectric constant of 140~160 @1MHz and a negative capacitance temperature coefficient of -(1500±500)ppm / ℃ and (-55~125)℃.

[0009] Among the added modifiers, La2O3 and Al2O3 may form nanoscale second-phase particles (such as LaAlO3) or adsorb at grain boundaries at high temperatures, hindering grain boundary migration through the Zener pinning effect, thereby inhibiting grain growth. La2O3 particles can also act as heterogeneous nucleation nuclei, increasing the nucleation rate and making the grain size smaller and more uniform. Al2O3 itself has high hardness (Mohs hardness 9, second only to diamond and silicon carbide) and high compressive strength (~2-4 GPa). Al2O3 is uniformly dispersed in the ceramic body in the form of nanoparticles or microparticles, hindering dislocation movement and improving the material strength. Among the added modifiers, La2O3 and MnO2 inhibit oxygen vacancies, reduce dielectric loss, hinder carrier migration, and reduce leakage current. Al2O3 hinders oxygen ion or electron migration, increases resistivity, reduces leakage conduction loss, refines grains, and reduces grain boundary defects.

[0010] The added cooling agents TiO2, SiO2, and ZnO can reduce the contact angle (θ) between the liquid phase and the solid particles, allowing them to spread better on the particle surface and promoting particle rearrangement and dissolution-precipitation processes. TiO2 and Al2O3 can form a eutectic liquid phase, enhancing grain boundary diffusion. SiO2 can dissolve some Al2O3 ceramic particles and reprecipitate at the grain boundaries, promoting densification. ZnO segregates at the grain boundaries, inhibiting excessive grain growth and maintaining a fine-grained structure.

[0011] Thus, the dielectric constant of the prepared ceramic substrate material is 140~160 @1MHz; the dielectric loss is ≤0.0005@1MHz, and the negative capacitance temperature coefficient is -(1500±500)ppm / ℃, (-55~125)℃, which can compensate for capacitance drift caused by temperature changes and avoid signal distortion. In addition, the ceramic substrate material has high bending strength (≥250MPa), ensuring the high reliability of miniaturized chip microwave single-layer ceramic capacitors. The prepared ceramic substrate is flat and non-deformable, has good rectangularity, excellent surface characteristics, a surface roughness of (100~200)nm, warpage ≤0.3%, good adhesion to the gold layer (TiWAu), and high bonding strength.

[0012] Furthermore, the modifier includes La2O3, Al2O3 and / or MnO2.

[0013] Furthermore, by mass percentage, the modifier comprises 1.0 wt% to 2.5 wt% La2O3, 0.5 wt% to 2.5 wt% Al2O3, and 0 to 0.5 wt% MnO2.

[0014] Furthermore, the cooling agent includes TiO2, ZnO and / or SiO2.

[0015] Furthermore, by mass percentage, the cooling agent comprises 1.0wt%~10wt% TiO2, 0~5wt% SiO2, and 1.0wt%~10wt% ZnO.

[0016] Secondly, this application provides a method for preparing a dielectric ceramic substrate material with a negative capacitance temperature coefficient, comprising the following steps:

[0017] CaTiO3, SrTiO3, MgTiO3, modifier, and cooling agent are mixed in a certain proportion and then ball-milled to obtain ceramic material;

[0018] Ceramic slurry is obtained by ball milling ceramic materials, binders, plasticizers, and additives into an organic solvent.

[0019] The ceramic slurry was prepared into ceramic films using a casting film forming machine;

[0020] The ceramic films are stacked, cut, and pressed into green bodies. The green bodies are then sintered to obtain ceramic substrate material.

[0021] In the preparation of ceramic materials, the materials are ball-milled for 20 to 28 hours according to the ratio of material:ball:water = 1:5:(0.8~1.5), then dried and sieved.

[0022] In the preparation of ceramic slurry, the ratio of ceramic material to zirconium spheres is 1:(3~10).

[0023] The additives used include, but are not limited to, dispersants and defoamers.

[0024] In the process of preparing ceramic films using a casting film forming machine, the viscosity of the slurry is controlled within the range of 500cp to 1500cp.

[0025] The sintering temperature is 1200℃~1300℃.

[0026] Furthermore, the organic solvent is a mixture of anhydrous ethanol and toluene, wherein the mass ratio of anhydrous ethanol to toluene is 1:(1~5).

[0027] Furthermore, the adhesive comprises polyvinyl butyral.

[0028] Furthermore, the plasticizer includes dioctyl phthalate.

[0029] Thirdly, this application provides a miniaturized chip microwave single-layer ceramic capacitor, comprising the above-mentioned ceramic substrate material or a ceramic substrate material prepared by the above-mentioned preparation method.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] (1) The ceramic substrate material in this invention has excellent bending strength, good surface roughness and bonding strength, and can be used to prepare miniaturized chip microwave single-layer ceramic capacitors with a dielectric constant of 140~160 (@1MHz), dielectric loss tanδ≤0.0005 (@1MHz) and bending strength ≥250MPa.

[0032] (2) The ceramic substrate material of the present invention has a negative capacitance temperature coefficient (-(1500±500)ppm / ℃, (-55~125)℃), which can compensate for capacitance drift caused by temperature change and avoid signal distortion.

[0033] (3) The ceramic substrate material of the present invention is flat and does not deform, has good rectangularity, has excellent surface properties, surface roughness (100~200) nm, warpage ≤0.3%, and bonding strength with TiWAu layer reaches 12.67gF. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 shows the XRD patterns of the ceramic substrate materials prepared in Examples 2, 4, Comparative Example 1, and Comparative Example 4 of the present invention;

[0036] Figure 2 shows SEM images of the ceramic substrate materials prepared in Examples 2(a), 4(b), Comparative Example 1(c), and Comparative Example 4(d) of the present invention.

[0037] Figure 3 shows the measured results of the flexural strength of the ceramic substrate material prepared in Example 4 of the present invention;

[0038] Figure 4 is a physical image of the ceramic substrate material prepared in Example 4 of the present invention;

[0039] Figure 5 is a histogram of the bonding strength of the ceramic substrate material prepared in Example 4 of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0041] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0042] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those different embodiments or examples.

[0043] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0044] Example 1

[0045] This embodiment provides a method for preparing a dielectric ceramic substrate material with a negative capacitance temperature coefficient. The formulation in step S1 is as follows: 76wt% CaTiO3, 12.8wt% SrTiO3, 5wt% MgTiO3, 0.5wt% La2O3, 1wt% Al2O3, 0.2wt% MnO2, 1.0wt% TiO2, and 3.5wt% ZnO.

[0046] The specific preparation method is as follows:

[0047] S1. Mix 760g of CaTiO3, 128g of SrTiO3, 50g of MgTiO3, 5g of La2O3, 10g of Al2O3, 2g of MnO2, 10g of TiO2, and 35g of ZnO, and ball mill them at a ratio of material:ball:water = 1:5:1.5 for 28 hours. Then dry and sieve to obtain ceramic material.

[0048] S2. Add 67g of ceramic material, 3.5g of polyvinyl butyral, 1.5g of dioctyl phthalate, and 0.5g of ammonium polyacrylate to 10.5g of anhydrous ethanol and 17g of toluene, and ball mill the mixture. The ratio of ceramic material to zirconium balls is 1:10 to obtain a ceramic slurry.

[0049] S3. Control the viscosity of the slurry at 500cp and use a casting film forming machine to prepare ceramic films from the ceramic slurry.

[0050] S4. After stacking the ceramic films, cut them and press them into green blanks. Then, sinter the green blanks at a temperature of 1300℃ to obtain ceramic substrate materials.

[0051] Example 2

[0052] This embodiment provides a method for preparing a dielectric ceramic substrate material with a negative capacitance temperature coefficient. Unlike Embodiment 1, the formulation composition in steps S1 and S2 of this embodiment is different. The formulation composition in step S1 is: 80wt% CaTiO3, 8wt% SrTiO3, 3wt% MgTiO3, 2wt% La2O3, 2wt% Al2O3, 0.5wt% MnO2, 1.0wt% TiO2, and 3.5wt% ZnO.

[0053] The specific preparation method is as follows:

[0054] S1. Mix 800g of CaTiO3, 80g of SrTiO3, 30g of MgTiO3, 20g of La2O3, 20g of Al2O3, 5g of MnO2, 10g of TiO2, and 35g of ZnO. Then ball mill the mixture at a ratio of material:ball:water = 1:5:1.5 for 28 hours. After drying and sieving, the ceramic material is obtained.

[0055] S2. Add 64g of ceramic material, 3.5g of polyvinyl butyral, and 1.5g of dioctyl phthalate to 10.25g of anhydrous ethanol and 20.75g of toluene, and ball mill the mixture. The ratio of ceramic material to zirconium balls is 1:8 to obtain a ceramic slurry.

[0056] S3. Control the viscosity of the slurry at 500cp and use a casting film forming machine to prepare ceramic films from the ceramic slurry.

[0057] S4. After stacking the ceramic films, cut them and press them into green blanks. Then, sinter the green blanks at a temperature of 1300℃ to obtain ceramic substrate materials.

[0058] Example 3

[0059] This embodiment provides a method for preparing a dielectric ceramic substrate material with a negative capacitance temperature coefficient. Unlike Embodiment 1, the formulation composition in steps S1 and S2 and the viscosity control in step S3 are different. The formulation composition in step S1 is: 84.8 wt% CaTiO3, 2 wt% SrTiO3, 8 wt% MgTiO3, 1 wt% La2O3, 0.5 wt% Al2O3, 0.2 wt% MnO2, 1.5 wt% TiO2, 1 wt% SiO2, and 1 wt% ZnO.

[0060] The specific preparation method is as follows:

[0061] S1. Mix 848g of CaTiO3, 20g of SrTiO3, 80g of MgTiO3, 10g of La2O3, 5g of Al2O3, 2g of MnO2, 15g of TiO2, 10g of SiO2, and 10g of ZnO. Then ball mill the mixture at a ratio of material:ball:water = 1:5:1.5 for 28 hours. After drying and sieving, the ceramic material is obtained.

[0062] S2. Add 66.5g of ceramic material, 3g of polyvinyl butyral, 1g of dioctyl phthalate, and 0.5g of ammonium polyacrylate to 10.25g of anhydrous ethanol and 18.75g of toluene, and ball mill the mixture. The ratio of ceramic material to zirconium balls is 1:5 to obtain a ceramic slurry.

[0063] S3. Control the viscosity of the slurry at 1000cp and use a casting film forming machine to prepare ceramic films from the ceramic slurry.

[0064] S4. After stacking the ceramic films, cut them and press them into green blanks. Then, sinter the green blanks at a temperature of 1300℃ to obtain ceramic substrate materials.

[0065] Example 4

[0066] This embodiment provides a method for preparing a dielectric ceramic substrate material with a negative capacitance temperature coefficient. Unlike Embodiment 3, the formulations in steps S1 and S2 and the sintering conditions in step S4 are different. The formulation in step S1 is: 85.9 wt% CaTiO3, 7.6 wt% SrTiO3, 1 wt% MgTiO3, 1 wt% La2O3, 0.5 wt% Al2O3, 1.5 wt% TiO2, 1 wt% SiO2, and 1.5 wt% ZnO.

[0067] The specific preparation method is as follows:

[0068] S1. Mix 859g of CaTiO3, 76g of SrTiO3, 10g of MgTiO3, 10g of La2O3, 5g of Al2O3, 15g of TiO2, 10g of SiO2, and 15g of ZnO, and ball mill them at a ratio of material:ball:water = 1:5:1.2 for 24 hours. Then dry and sieve to obtain ceramic material.

[0069] S2. Add 66.5g of ceramic material, 3g of polyvinyl butyral, 1g of dioctyl phthalate, and 0.5g of ammonium polyacrylate to 10.5g of anhydrous ethanol and 18.5g of toluene, and ball mill the mixture. The ratio of ceramic material to zirconium balls is 1:5 to obtain a ceramic slurry.

[0070] S3. Control the viscosity of the slurry at 1000cp and use a casting film forming machine to prepare ceramic films from the ceramic slurry.

[0071] S4. After stacking the ceramic films, cut them and press them into green blanks. Then, sinter the green blanks at a temperature of 1250℃ to obtain ceramic substrate materials.

[0072] Example 5

[0073] This embodiment provides a method for preparing a dielectric ceramic substrate material with a negative capacitance temperature coefficient. Unlike Embodiment 4, the formulation composition in steps S1 and S2 and the viscosity control in step S3 are different. The formulation composition in step S1 is: 87.1 wt% CaTiO3, 3.9 wt% SrTiO3, 1.5 wt% MgTiO3, 1.5 wt% La2O3, 1.5 wt% Al2O3, 1 wt% TiO2, and 3.5 wt% ZnO.

[0074] The specific preparation method is as follows:

[0075] S1. Mix 871g of CaTiO3, 39g of SrTiO3, 15g of MgTiO3, 15g of La2O3, 15g of Al2O3, 10g of TiO2, and 35g of ZnO, and ball mill them for 24 hours at a ratio of material:ball:water = 1:5:0.8. Then dry and sieve to obtain ceramic material.

[0076] S2. Add 67.5g of ceramic material, 2g of polyvinyl butyral, 1g of dioctyl phthalate, and 0.5g of ammonium polyacrylate to 7.25g of anhydrous ethanol and 21.75g ​​of toluene, and ball mill the mixture. The ratio of ceramic material to zirconium balls is 1:3 to obtain a ceramic slurry.

[0077] S3. Control the viscosity of the slurry at 1500cp and use a casting film forming machine to prepare ceramic films from the ceramic slurry.

[0078] S4. After stacking the ceramic films, cut them and press them into green blanks. Then, sinter the green blanks at a temperature of 1250℃ to obtain ceramic substrate materials.

[0079] Example 6

[0080] This embodiment provides a method for preparing a dielectric ceramic substrate material with a negative capacitance temperature coefficient. Unlike Embodiment 5, the formulations in steps S1 and S2 and the sintering conditions in step S4 are different. The formulation in step S1 is 90wt% CaTiO3, 3wt% SrTiO3, 1wt% MgTiO3, 1wt% La2O3, 0.5wt% Al2O3, 2wt% TiO2, 1.5wt% SiO2, and 1wt% ZnO.

[0081] The specific preparation method is as follows:

[0082] S1. Mix 900g of CaTiO3, 30g of SrTiO3, 10g of MgTiO3, 10g of La2O3, 5g of Al2O3, 20g of TiO2, 15g of SiO2, and 10g of ZnO. Then, ball mill the mixture at a ratio of material:ball:water = 1:5:1.2 for 20 hours. After drying and sieving, the ceramic material is obtained.

[0083] S2. Add 65.5g of ceramic material, 2.5g of polyvinyl butyral, 1g of dioctyl phthalate, and 0.5g of ammonium polyacrylate to 15.25g of anhydrous ethanol and 15.25g of toluene, and ball mill the mixture. The ratio of ceramic material to zirconium balls is 1:3 to obtain a ceramic slurry.

[0084] S3. Control the viscosity of the slurry at 1500cp and use a casting film forming machine to prepare ceramic films from the ceramic slurry.

[0085] S4. After stacking the ceramic films, cut them and press them into green blanks. Then, sinter the green blanks at a temperature of 1200℃ to obtain ceramic substrate materials.

[0086] Example 7

[0087] This embodiment provides a method for preparing a dielectric ceramic substrate material with a negative capacitance temperature coefficient. Unlike Embodiment 6, the formulation composition in steps S1 and S2 and the viscosity control in step S3 are different. The formulation composition in step S1 is 93.5 wt% CaTiO3, 2 wt% SrTiO3, 1 wt% MgTiO3, 0.5 wt% La2O3, 1 wt% Al2O3, 1 wt% TiO2, and 1 wt% ZnO.

[0088] The specific preparation method is as follows:

[0089] S1. Mix 935g of CaTiO3, 20g of SrTiO3, 10g of MgTiO3, 5g of La2O3, 10g of Al2O3, 10g of TiO2, and 10g of ZnO, and ball mill them for 20 hours at a ratio of material:ball:water = 1:5:0.8. Then dry and sieve to obtain ceramic material.

[0090] S2. Add 65g of ceramic material, 3g of polyvinyl butyral, 1g of dioctyl phthalate, and 0.5g of ammonium polyacrylate to 15.25g of anhydrous ethanol and 15.25g of toluene, and ball mill the mixture. The ratio of ceramic material to zirconium balls is 1:5 to obtain a ceramic slurry.

[0091] S3. Control the viscosity of the slurry at 1000cp and use a casting film forming machine to prepare ceramic films from the ceramic slurry.

[0092] S4. After stacking the ceramic films, cut them and press them into green blanks. Then, sinter the green blanks at a temperature of 1200℃ to obtain ceramic substrate materials.

[0093] Comparative Example 1

[0094] This comparative example provides a method for preparing a dielectric ceramic substrate material. Unlike Example 2, the proportion of CaTiO3 in this comparative example is less than 76 wt%, and the proportion of cooling agent is greater than 4.5 wt%. The formulation in step S1 is as follows: 70 wt% CaTiO3, 16.5 wt% SrTiO3, 2 wt% MgTiO3, 2 wt% La2O3, 2 wt% Al2O3, 0.5 wt% MnO2, 5 wt% TiO2, and 2 wt% ZnO.

[0095] The specific preparation method is as follows:

[0096] S1. Mix 700g of CaTiO3, 165g of SrTiO3, 20g of MgTiO3, 20g of La2O3, 20g of Al2O3, 5g of MnO2, 50g of TiO2, and 20g of ZnO. Then ball mill the mixture at a ratio of material:ball:water = 1:5:1.5 for 28 hours. After drying and sieving, the ceramic material is obtained.

[0097] S2. Add 58.5g of ceramic material, 2g of polyvinyl butyral, 1.5g of dioctyl phthalate, and 0.5g of ammonium polyacrylate to 12.5g of anhydrous ethanol and 25g of toluene, and ball mill the mixture. The ratio of ceramic material to zirconium balls is 1:8 to obtain a ceramic slurry.

[0098] S3. Control the viscosity of the slurry at 500cp and use a casting film forming machine to prepare ceramic films from the ceramic slurry.

[0099] S4. After stacking the ceramic films, cut them and press them into green blanks. Then, sinter the green blanks at a temperature of 1300℃ to obtain ceramic substrate materials.

[0100] Comparative Example 2

[0101] This comparative example provides a method for preparing a dielectric ceramic substrate material. Unlike Example 1, this comparative example contains more than 8.5 wt% MgTiO3, more than 3.2 wt% modifier, and only 2 wt% cooling agent. The formulation in step S1 is as follows: 76 wt% CaTiO3, 8.5 wt% SrTiO3, 10 wt% MgTiO3, 1.5 wt% La2O3, 1.5 wt% Al2O3, 0.5 wt% MnO2, 1 wt% TiO2, and 1 wt% ZnO.

[0102] The specific preparation method is as follows:

[0103] S1. 760g of CaTiO3, 85g of SrTiO3, 100g of MgTiO3, 15g of La2O3, 15g of Al2O3, 5g of MnO2, 10g of TiO2, and 10g of ZnO are ball-milled in a ratio of material:ball:water = 1:5:1.5 for 28 hours, then dried and sieved to obtain the ceramic material.

[0104] S2. Add 67g of ceramic material, 2.5g of polyvinyl butyral, and 1g of dioctyl phthalate to 12.5g of anhydrous ethanol and 17g of toluene, and ball mill the mixture. The ratio of ceramic material to zirconium balls is 1:10 to obtain a ceramic slurry.

[0105] S3. Control the viscosity of the slurry at 500cp and use a casting film forming machine to prepare ceramic films from the ceramic slurry.

[0106] S4. After stacking the ceramic films, cut them and press them into green blanks. Then, sinter the green blanks at a temperature of 1300℃ to obtain ceramic substrate materials.

[0107] Comparative Example 3

[0108] This comparative example provides a method for preparing a dielectric ceramic substrate material. Unlike Examples 1, 4, and 5, this comparative example does not contain MgTiO3, and the SrTiO3 content is higher than 15.5 wt%. The formulation composition in step S1 is: 76.1 wt% CaTiO3, 16.4 wt% SrTiO3, 1.5 wt% La2O3, 1.5 wt% Al2O3, 1 wt% TiO2, 1 wt% SiO2, and 2.5 wt% ZnO.

[0109] The specific preparation method is as follows:

[0110] S1. Mix 761g of CaTiO3, 164g of SrTiO3, 15g of La2O3, 15g of Al2O3, 10g of TiO2, 10g of SiO2, and 25g of ZnO, and ball mill them for 24 hours at a ratio of material:ball:water = 1:5:1.2. Then dry and sieve to obtain ceramic material.

[0111] S2. Add 63g of ceramic material, 4g of polyvinyl butyral, 1.5g of dioctyl phthalate, and 0.5g of ammonium polyacrylate to 10.5g of anhydrous ethanol and 20.5g of toluene, and ball mill the mixture. The ratio of ceramic material to zirconium balls is 1:8 to obtain a ceramic slurry.

[0112] S3. Control the viscosity of the slurry at 1500cp and use a casting film forming machine to prepare ceramic films from the ceramic slurry.

[0113] S4. After stacking the ceramic films, cut them and press them into green blanks. Then, sinter the green blanks at a temperature of 1200℃ to obtain ceramic substrate materials.

[0114] Comparative Example 4

[0115] This comparative example provides a method for preparing a dielectric ceramic substrate material. Unlike Examples 2 and 3, this comparative example does not contain a cooling agent. The formulation in step S1 is: 80wt% CaTiO3, 10.5wt% SrTiO3, 8wt% MgTiO3, 1wt% La2O3, and 0.5wt% Al2O3.

[0116] The specific preparation method is as follows:

[0117] S1. Mix 800g of CaTiO3, 105g of SrTiO3, 80g of MgTiO3, 10g of La2O3 and 5g of Al2O3, and ball mill them for 28 hours at a ratio of material:ball:water = 1:5:1.5. Then dry and sieve to obtain ceramic material.

[0118] S2. Add 60g of ceramic material, 2g of polyvinyl butyral, and 1g of dioctyl phthalate to 14.5g of anhydrous ethanol and 14.5g of toluene, and ball mill the mixture. The ratio of ceramic material to zirconium balls is 1:5 to obtain a ceramic slurry.

[0119] S3. Control the viscosity of the slurry at 1500cp and use a casting film forming machine to prepare ceramic films from the ceramic slurry.

[0120] S4. After stacking the ceramic films, cut them and press them into green blanks. Then, sinter the green blanks at a temperature of 1200℃ to obtain ceramic substrate materials.

[0121] Comparative Example 5

[0122] This comparative example provides a method for preparing a dielectric ceramic substrate material. Unlike Examples 6 and 7, this comparative example does not contain a modifier. The formulation in step S1 is: 91.5 wt% CaTiO3, 3 wt% SrTiO3, 1 wt% MgTiO3, 2 wt% TiO2, 1.5 wt% SiO2, and 1 wt% ZnO.

[0123] The specific preparation method is as follows:

[0124] S1. Mix 915g of CaTiO3, 30g of SrTiO3, 10g of MgTiO3, 20g of TiO2, 15g of SiO2, and 10g of ZnO, and ball mill them for 20 hours at a ratio of material:ball:water = 1:5:0.8. Then dry and sieve to obtain ceramic material.

[0125] S2. Add 66g of ceramic material, 3g of polyvinyl butyral, 1.5g of dioctyl phthalate, and 0.5g of ammonium polyacrylate to 10.5g of anhydrous ethanol and 18.5g of toluene, and ball mill the mixture. The ratio of ceramic material to zirconium balls is 1:8 to obtain a ceramic slurry.

[0126] S3. Control the viscosity of the slurry at 500cp and use a casting film forming machine to prepare ceramic films from the ceramic slurry.

[0127] S4. After stacking the ceramic films, cut them and press them into green blanks. Then, sinter the green blanks at a temperature of 1200℃ to obtain ceramic substrate materials.

[0128] The ceramic substrate materials prepared using the methods of Examples 2, 4, Comparative Examples 1, and 4 were tested. Figure 1 shows the XRD patterns of the aforementioned ceramic substrate materials. As can be seen from the figure, the characteristic peak of the ceramic substrate materials prepared using the methods of Examples 2, 4, Comparative Examples 1, and 4 is (112), which corresponds to the peak position of the CaTiO3 phase on the PDF card. There are no impurity peaks, and the peak position of the characteristic peak (112) is... There are slight changes, which are clearly visible. The peak position in Comparative Example 1 shifts most significantly to a lower angle. This is because this component contains many large-sized Sr cations. 2+ Enter Ca 2+ The characteristic peak position angle of Example 2 is the highest, which is because its component Sr... 2+ least.

[0129] Figure 2 shows SEM images of the ceramic substrate materials prepared by the methods of Example 2(a), Example 4(b), Comparative Example 1(c), and Comparative Example 4(d). As can be seen from Figure 2, the surface morphology of Example 2 and Example 4 both exhibit a uniform and dense structure, while Comparative Example 1 has a small amount of glass phase attached to the particle surface, and Comparative Example 4 has dispersed grains, exhibiting a non-dense state that is not yet fully sintered.

[0130] Figure 3 shows the bending strength test results of the ceramic substrate material prepared in Example 4. Eleven test samples were taken and tested respectively. As can be seen from Figure 3, the value is higher than the index of 250 MPa (red dotted line in the figure), and the average value is 307 MPa. The inserted figure is a curve of deformation and force during the test of the 11 test samples. The sample suddenly broke at a certain point.

[0131] Figures 4 and 5 show the physical images of the ceramic substrate material prepared in Example 4 and the histogram of the bonding strength of the ceramic substrate. As can be seen from the figures, the bonding strength of the sputtered TiWAu layer on the ceramic substrate prepared in Example 4, obtained by wire bonding with gold wire at 5 points on each sample, shows a normal distribution with a mean value of 12.67 gF.

[0132] The warpage of the ceramic substrate was tested using Appendix A of GB / T14619-2013 "Alumina Ceramic Substrates for Thick Film Integrated Circuits". Using the same thickness, a standard of 3‰ was set to adjust the parallel plate spacing. A pass was marked as "○" indicating a warpage ≤ 3‰, and a fail was marked as "╳" indicating a warpage > 3‰. The dielectric constant and dielectric loss were measured using the parallel plate capacitance test method, and then determined using the formula... ,in It is the electrostatic constant, usually taken as 9.87 × 10⁻⁶. 9 N·m 2 / kg 2d is the spacing between parallel plates (meters), S is the area of ​​the parallel plates facing each other (square meters), and C is the capacitance (pF). Bending strength was determined using the three-point bending method on a computerized bending tester to obtain the maximum breaking force, which was then calculated using the formula... The calculations show that F is the maximum breaking force (in Newtons), L is the distance between support points (in millimeters), b is the width of the fracture section (in millimeters), and h is the thickness of the fracture section (in millimeters). The temperature coefficient was determined by testing the capacitance at 25℃, -55℃, 25℃, and 125℃ using a high and low temperature test chamber and a capacitance meter, respectively, according to the capacitance temperature coefficient. ,in, The capacitance at time t2 (in pF). The capacitance (in pF) is used as the reference point, which is generally the second 25°C. The roughness Ra is measured according to GB / T "Geometric Specifications of Products (GPS) Surface Structure Profilometry Contact (Stylus) Instruments". A contact profilometer is used with a 2μm probe and a stroke of 1cm. The bond strength is measured by pull-out test. A TiWAu layer is sputtered and gold wire is attached. Five points are attached to each sample.

[0133] The warpage, dielectric constant, dielectric loss, bending strength, temperature coefficient, roughness Ra, and bonding strength of the ceramic substrate materials prepared in Examples 1-7 and Comparative Examples 1-5 were tested, and the test results are shown in Table 1.

[0134] Table 1 shows the warpage, dielectric constant, dielectric loss, flexural strength, temperature coefficient of capacitance, roughness, and bonding strength of the ceramic substrate materials prepared in each embodiment and comparative example.

[0135]

[0136] Note: "○" indicates pass, "╳" indicates fail.

[0137] In Table 1, Examples 1 to 7 all meet the component ratio settings, and their warpage, dielectric constant, dielectric loss, bending strength, temperature coefficient, roughness Ra, and bonding strength also meet the following requirements: dielectric constant (1MHz): 140~160; dielectric loss (1MHz): ≤0.0005; temperature coefficient of capacitance (-55℃~125℃): -(1500±500)ppm / ℃; bending strength ≥250MPa; surface roughness: (100~200)nm; warpage ≤0.3%; and good adhesion to the sputtered layer, making it difficult to fall off. Compared to Example 2, Comparative Example 1 had CaTiO3 below 76 wt%, SrTiO3 above 15.5 wt%, and cooling agent reaching 7 wt%. This resulted in ceramic deformation, surface precipitates, compromised density, increased dielectric loss, decreased flexural strength, and increased surface roughness. Comparative Example 2, compared to Example 1, had MgTiO3 above 8.5 wt%, modifier > 3.2 wt%, and cooling agent at only 2 wt%, which was at the critical point. Therefore, the ceramic was not fully fired, resulting in numerous air-filled pores, a low dielectric constant, high dielectric loss, low strength, easy breakage, and low flexural strength. Compared with Examples 1, 4, and 5, Example 3 had no MgTiO3, SrTiO3 was higher than the maximum added value, the cooling agent was at the maximum added value, and the dielectric constant and capacitance temperature coefficient were out of balance. Compared with Examples 2 and 3, Example 4 had no added cooling agent, the ceramic body was not fully fired, many pores inside the ceramic body were filled with air, the dielectric constant was low, the dielectric loss was high, the ceramic body had low strength, was easy to break, and had low bending strength. Compared with Examples 6 and 7, Example 5 had the cooling agent at the maximum added value, no modifier was added, the ceramic body could be formed, but the grains grew abnormally, the dielectric loss was high, and the bending strength was low.

[0138] Finally, it should be noted that the specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. It is obvious to those skilled in the art that this application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this application is defined by the appended claims rather than the foregoing description, and therefore all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within this application.

Claims

1. A dielectric ceramic substrate material with a negative capacitance temperature coefficient, characterized in that, By mass percentage, it comprises 76wt%~93.5wt% CaTiO3, 2wt%~15.5wt% SrTiO3, 1wt%~8.5wt% MgTiO3, 1.5wt%~3.2wt% modifier, and 2wt%~4.5wt% cooling agent; the modifier includes La2O3 and Al2O3; the cooling agent includes TiO2 and ZnO.

2. A method for preparing a dielectric ceramic substrate material with a negative capacitance temperature coefficient, characterized in that, Includes the following steps: By mass percentage, 76wt%~93.5wt% of CaTiO3, 2wt%~15.5wt% of SrTiO3, 1wt%~8.5wt% of MgTiO3, 1.5wt%~3.2wt% of modifier, and 2wt%~4.5wt% of cooling agent are ball-milled to obtain ceramic material; the modifier includes La2O3 and Al2O3; the cooling agent includes TiO2 and ZnO; ceramic material, binder, plasticizer, and additives are added to an organic solvent and ball-milled to obtain ceramic slurry; the additives include dispersant and defoamer; the ceramic slurry is used to prepare ceramic films using a casting film forming machine; the ceramic films are stacked, cut, pressed into green bodies, and then sintered to obtain ceramic substrate material.

3. The method for preparing a dielectric ceramic substrate material with a negative capacitance temperature coefficient according to claim 2, characterized in that, The organic solvent is a mixture of anhydrous ethanol and toluene, wherein the mass ratio of anhydrous ethanol to toluene is 1:(1~5).

4. The method for preparing a dielectric ceramic substrate material with a negative capacitance temperature coefficient according to claim 3, characterized in that, The adhesive comprises polyvinyl butyral.

5. The method for preparing a dielectric ceramic substrate material with a negative capacitance temperature coefficient according to claim 3, characterized in that, The plasticizer includes dioctyl phthalate.

6. A miniaturized chip-type microwave single-layer ceramic capacitor, characterized in that, Includes the ceramic substrate material as described in claim 1 or the ceramic substrate material prepared by the preparation method described in any one of claims 2 to 5.

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