High-strength low-dielectric-constant ceramic substrate and preparation method thereof

Abstract

The invention relates to the technical field of ceramic substrates, and provides a high-strength low-dielectric-constant ceramic substrate and a preparation method thereof. The high-strength low-dielectric-constant ceramic substrate is prepared from the following raw material components in parts by weight: 90 parts of aluminum oxide, 9-15 parts of doped zinc silicate, 4-6 parts of a sintering aid, 4-6 parts of a dispersing agent, 6-8 parts of a binder and 60 parts of a solvent, the preparation method of the doped zinc silicate comprises the following steps: uniformly mixing zinc silicate and cobaltous oxide, ball-milling, calcining and crushing to obtain the doped zinc silicate. According to the technical scheme, the problem that the dielectric constant reduction degree of the ceramic substrate is limited in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of ceramic substrate technology, specifically to a high-strength, low-dielectric-constant ceramic substrate and its preparation method. Background Technology

[0002] With the continuous advancement of modern electronics industry, such as microwave technology, 5G communication, and advanced packaging technology, the performance requirements for ceramic substrates—a key material in electronic components—are becoming increasingly stringent. As a critical component in electronic components, the dielectric properties of ceramic substrates directly affect the signal transmission quality and long-term operational stability of electronic devices.

[0003] Currently, alumina ceramics have the drawback of high dielectric constant and large change in dielectric constant with temperature. To solve this problem, materials with relatively low dielectric constant and small change with temperature (such as zinc silicate) are usually added. However, zinc silicate usually produces zinc oxide (ZnO) phase during high-temperature sintering, which is detrimental to dielectric properties. This limits its effect on reducing dielectric constant to some extent.

[0004] Therefore, developing a ceramic substrate that can effectively reduce the dielectric constant of the ceramic substrate is of great significance for meeting the urgent need for low dielectric constant in modern high-frequency electronic equipment. Summary of the Invention

[0005] This invention proposes a high-strength, low-dielectric-constant ceramic substrate and its preparation method, which solves the problem of limited reduction in dielectric constant of ceramic substrates in related technologies.

[0006] The technical solution of the present invention is as follows: This invention proposes a high-strength, low-dielectric-constant ceramic substrate, the raw materials of which include the following components in parts by weight: 90 parts alumina, 9-15 parts doped zinc silicate, 4-6 parts sintering aid, 4-6 parts dispersant, 6-8 parts binder, and 60 parts solvent; The method for preparing the doped zinc silicate includes: Zinc silicate and cobalt oxide are mixed evenly, ball-milled, calcined, and pulverized to obtain the doped zinc silicate.

[0007] In the high-strength, low-dielectric-constant ceramic substrate of this invention, alumina is used as the base material. Alumina has the advantages of high strength and high hardness, which can provide basic mechanical support for the ceramic substrate. Combined with zinc silicate doping, and with the action of sintering aids, dispersants, binders and solvents, a ceramic substrate with a relatively dense and stable internal structure can be prepared.

[0008] As a further technical solution, the weight ratio of zinc silicate to cobalt oxide is 10:1 to 3, for example, it can be 10:1, 10:1.5, 10:1.6, 10:1.8, 10:2, 10:2.2, 10:2.5, 10:2.8, or 10:3, preferably 10:1.5 to 2.5.

[0009] In the high-strength, low-dielectric-constant ceramic substrate of this invention, by adjusting the content ratio of zinc silicate and cobalt oxide, when the weight ratio of zinc silicate to cobalt oxide is 10:1.5~2.5, the doping effect of cobalt oxide on zinc silicate is better, which can further reduce the dielectric constant of the ceramic substrate. At 10 GHz, its dielectric constant can be reduced to 5.1~5.4.

[0010] As a further technical solution, during ball milling, the ball milling speed is 200~300 rpm and the ball milling time is 20~40 min.

[0011] As a further technical solution, during the calcination, the calcination temperature is 1050~1100℃ under a nitrogen atmosphere, and the calcination time is 1~2h.

[0012] In the high-strength, low-dielectric-constant ceramic substrate of this invention, when preparing doped zinc silicate, calcination is carried out under a nitrogen atmosphere, which can reduce the oxidation of cobalt suboxide to a certain extent, thereby ensuring that more cobalt suboxide combines with zinc silicate.

[0013] As a further technical solution, the particle size of the doped zinc silicate is 50~80μm, for example, it can be 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, or 80μm, preferably 50μm, 65μm, or 80μm, and more preferably 65μm.

[0014] As a further technical solution, the raw material also includes mullite microspheres, and the amount of mullite microspheres added is 5% to 9% of the weight of the alumina, for example, it can be 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, or 9%.

[0015] As a further technical solution, the sintering aid includes one or two of Y2O3 and MgO, preferably Y2O3.

[0016] As a further technical solution, the dispersant includes one or both of triethyl phosphate and tributyl phosphate, preferably triethyl phosphate.

[0017] As a further technical solution, the adhesive includes polyvinyl butyral; The solvent includes one or both of ethanol and acetone, preferably ethanol.

[0018] This invention proposes a method for preparing a high-strength, low-dielectric-constant ceramic substrate, comprising the following steps: S1. Mix all components evenly and ball mill to obtain cast slurry; S2. The cast slurry is degassed, cast into shape, dried, and stamped to obtain a blank. S3. The blank is debonded and calcined to obtain the high-strength, low-dielectric-constant ceramic substrate.

[0019] As a further technical solution, in step S1, the ball milling speed is 100~300 rpm and the ball milling time is 1~2 hours.

[0020] As a further technical solution, in step S3, the calcination is carried out in a nitrogen atmosphere at a calcination temperature of 1300~1400℃ for 20~30min.

[0021] This invention also proposes a method for preparing a high-strength, low-dielectric-constant ceramic substrate, comprising the following steps: S0. Mix alumina and mullite microspheres evenly, then ball mill to obtain a premix; S1. Mix the premix and the remaining components evenly, and ball mill to obtain a casting slurry; S2. The cast slurry is degassed, cast into shape, dried, and stamped to obtain a blank. S3. The blank is debonded and calcined to obtain the high-strength, low-dielectric-constant ceramic substrate.

[0022] In this invention, a high-strength, low-dielectric-constant ceramic substrate is further incorporating mullite microspheres. The inventors discovered that the presence of mullite microspheres can slightly reduce the dielectric constant of the ceramic substrate after introducing doped zinc silicate. Simultaneously, the addition of mullite microspheres can improve the bending strength of the ceramic substrate to some extent. In the prior art, to reduce the dielectric constant of single-phase alumina inorganic materials, a second phase with a porous structure can be introduced. For this purpose, the inventors introduced mullite microspheres. They found that when mullite microspheres are mixed with alumina for pretreatment without the introduction of low-dielectric-constant doped zinc silicate, the dielectric constant of the ceramic substrate can be reduced to some extent, but the reduction effect is worse compared to that of doped zinc silicate. Introducing mullite microspheres simultaneously with doped zinc silicate can further reduce the dielectric constant of the ceramic substrate, but the reduction is relatively small. In addition, the introduction of mullite microspheres can effectively improve the bending strength of ceramic substrates. The reason may be that the premixing of alumina with mullite microspheres can better disperse the alumina. At the same time, when subjected to external forces, the mullite microspheres can also bear part of the load, so that the stress can be better dispersed, thereby improving the bending strength of ceramic substrates.

[0023] As a further technical solution, in step S0, the ball milling speed is 400~600 rpm and the ball milling time is 20~30 min.

[0024] The working principle and beneficial effects of this invention are as follows: In this invention, a high-strength, low-dielectric-constant ceramic substrate is prepared by doping zinc silicate with cobalt suboxide, which effectively reduces the dielectric constant of the ceramic substrate. Currently, to reduce the dielectric constant of alumina ceramic substrates, materials with low dielectric constants and less affected by temperature, such as zinc silicate, need to be added. However, zinc silicate produces a ZnO phase during high-temperature sintering, which is detrimental to dielectric properties. This limits the effectiveness of zinc silicate in reducing the dielectric constant of the ceramic substrate. To overcome this problem and maximize the effect of zinc silicate in reducing the dielectric constant, this invention uses cobalt suboxide to dope zinc silicate. By ball milling and calcining zinc silicate and cobalt suboxide, the cobalt suboxide and zinc silicate are fully combined. During the subsequent high-temperature sintering process of preparing the ceramic substrate, the formation of the ZnO phase is inhibited. Ultimately, the doping of zinc silicate with cobalt suboxide effectively reduces the dielectric constant of the ceramic substrate. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] In the following examples and comparative examples, the average particle size of alumina was 100 nm; the effective component content of zinc silicate was 99%; the effective component content of cobalt oxide was 99%; the polyvinyl butyral was TB-20; and the mullite microspheres were prepared by conventional spray drying granulation method with an average particle size of 100 μm.

[0027] Example 1 Methods for preparing doped zinc silicate include: 20 parts of zinc silicate and 2 parts of cobalt oxide were mixed evenly, ball-milled at 200 rpm for 40 min, calcined at 1050 °C for 2 h under nitrogen atmosphere, and then pulverized to obtain doped zinc silicate with a particle size of 50 μm. A method for preparing a high-strength, low-dielectric-constant ceramic substrate includes the following steps: S1. Mix 90 parts alumina, 9 parts doped zinc silicate, 4 parts Y2O3, 4 parts triethyl phosphate, 6 parts polyvinyl butyral and 60 parts ethanol evenly, and ball mill at 100 rpm for 2 hours to obtain a casting slurry. S2. The cast slurry is degassed, cast into shape, dried, and stamped to obtain a blank. S3. After debinding the blank, calcine it at 1300℃ for 30 minutes under a nitrogen atmosphere to obtain a high-strength, low-dielectric-constant ceramic substrate.

[0028] Example 2 Methods for preparing doped zinc silicate include: 20 parts of zinc silicate and 2 parts of cobalt oxide were mixed evenly, ball-milled at 250 rpm for 30 min, and then calcined at 1080 °C for 1.5 h under a nitrogen atmosphere. The mixture was then pulverized to obtain doped zinc silicate with a particle size of 65 μm. A method for preparing a high-strength, low-dielectric-constant ceramic substrate includes the following steps: S1. Mix 90 parts alumina, 12 parts doped zinc silicate, 5 parts Y2O3, 5 parts triethyl phosphate, 7 parts polyvinyl butyral and 60 parts ethanol evenly, and ball mill at 200 rpm for 1.5 h to obtain casting slurry. S2. The cast slurry is degassed, cast into shape, dried, and stamped to obtain a blank. S3. After debinding the blank, calcine it at 1350℃ for 25 minutes under a nitrogen atmosphere to obtain a high-strength, low-dielectric-constant ceramic substrate.

[0029] Example 3 Methods for preparing doped zinc silicate include: 20 parts of zinc silicate and 2 parts of cobalt oxide were mixed evenly, ball-milled at 300 rpm for 20 min, and then calcined at 1100 °C for 1 h under a nitrogen atmosphere. The mixture was then pulverized to obtain doped zinc silicate with a particle size of 80 μm. A method for preparing a high-strength, low-dielectric-constant ceramic substrate includes the following steps: S1. Mix 90 parts alumina, 15 parts doped zinc silicate, 6 parts Y2O3, 6 parts triethyl phosphate, 8 parts polyvinyl butyral and 60 parts ethanol evenly, and ball mill at 300 rpm for 1 hour to obtain a casting slurry. S2. The cast slurry is degassed, cast into shape, dried, and stamped to obtain a blank. S3. After debinding the blank, calcine it at 1400℃ for 20 minutes under a nitrogen atmosphere to obtain a high-strength, low-dielectric-constant ceramic substrate.

[0030] Example 4 The only difference between this embodiment and Embodiment 2 is that in the preparation method of zinc silicate doped in this embodiment, the amount of cobalt oxide added is 3 parts.

[0031] Example 5 The only difference between this embodiment and Embodiment 2 is that in the preparation method of zinc silicate doped in this embodiment, the amount of cobalt oxide added is 5 parts.

[0032] Example 6 The only difference between this embodiment and Embodiment 2 is that in the preparation method of zinc silicate doped in this embodiment, the amount of cobalt oxide added is 6 parts.

[0033] Example 7 The only difference between this embodiment and Embodiment 5 is that the preparation method of the high-strength, low-dielectric-constant ceramic substrate is different in this embodiment, specifically: S0. Mix 90 parts of alumina and 4.5 parts of mullite microspheres evenly, and ball mill at 500 rpm for 30 min to obtain a premix. S1. Mix the above premix, 12 parts of doped zinc silicate, 5 parts of Y2O3, 5 parts of triethyl phosphate, 7 parts of polyvinyl butyral and 60 parts of ethanol evenly, and ball mill at 200 rpm for 1.5 h to obtain the casting slurry. S2. The cast slurry is degassed, cast into shape, dried, and stamped to obtain a blank. S3. After debinding the blank, calcine it at 1350℃ for 25 minutes under a nitrogen atmosphere to obtain a high-strength, low-dielectric-constant ceramic substrate.

[0034] Example 8 The only difference between this embodiment and Embodiment 7 is that in this embodiment, 6.3 parts of mullite microspheres are added.

[0035] Example 9 The only difference between this embodiment and Embodiment 7 is that in this embodiment, the amount of mullite microspheres added is 8.1 parts.

[0036] Example 10 The only difference between this embodiment and Embodiment 7 is that the preparation method of the high-strength, low-dielectric-constant ceramic substrate is different in this embodiment, specifically: S1. Mix 90 parts alumina, 4.5 parts mullite microspheres, 12 parts doped zinc silicate, 5 parts Y2O3, 5 parts triethyl phosphate, 7 parts polyvinyl butyral and 60 parts ethanol evenly, and ball mill at 200 rpm for 1.5 h to obtain cast slurry. S2. The cast slurry is degassed, cast into shape, dried, and stamped to obtain a blank. S3. After debinding the blank, calcine it at 1350℃ for 25 minutes under a nitrogen atmosphere to obtain a high-strength, low-dielectric-constant ceramic substrate.

[0037] Comparative Example 1 The only difference between this comparative example and Example 2 is that the preparation method of the zinc silicate doped in this comparative example is different, specifically: 20 parts zinc silicate and 2 parts copper oxide were mixed evenly, ball-milled at 250 rpm for 30 min, and then calcined at 1080 °C for 1.5 h under a nitrogen atmosphere. After pulverization, doped zinc silicate with a particle size of 65 μm was obtained.

[0038] Comparative Example 2 The only difference between this comparative example and Example 2 is that the preparation method of the zinc silicate doped in this comparative example is different, specifically: 20 parts zinc silicate and 2 parts cobalt oxide were mixed evenly, ball-milled at 250 rpm for 30 min, and then calcined at 1080 °C for 1.5 h under a nitrogen atmosphere. After pulverization, doped zinc silicate with a particle size of 65 μm was obtained.

[0039] Comparative Example 3 The only difference between this comparative example and Example 2 is that in this comparative example, the zinc silicate dopant is replaced with an equal amount of zinc silicate.

[0040] Comparative Example 4 The only difference between this comparative example and Example 2 is that no zinc silicate was added in this comparative example.

[0041] Comparative Example 5 The only difference between this comparative example and Example 2 is that the preparation method of the high-strength, low-dielectric-constant ceramic substrate is different in this comparative example, specifically: S1. Mix 90 parts alumina, 12 parts zinc silicate, 1.2 parts cobalt oxide, 5 parts Y2O3, 5 parts triethyl phosphate, 7 parts polyvinyl butyral and 60 parts ethanol evenly, and ball mill at 200 rpm for 1.5 h to obtain cast slurry. S2. The cast slurry is degassed, cast into shape, dried, and stamped to obtain a blank. S3. After debinding the blank, calcine it at 1350℃ for 25 minutes under a nitrogen atmosphere to obtain a high-strength, low-dielectric-constant ceramic substrate.

[0042] Comparative Example 6 The only difference between this comparative example and Example 2 is that the preparation method of the high-strength, low-dielectric-constant ceramic substrate is different in this comparative example, specifically: S0. Mix 90 parts of alumina and 4.5 parts of mullite microspheres evenly, and ball mill at 500 rpm for 30 min to obtain a premix. S1. Mix the above premix, 5 parts Y2O3, 5 parts triethyl phosphate, 7 parts polyvinyl butyral and 60 parts ethanol evenly, and ball mill at 200 rpm for 1.5 h to obtain the casting slurry. S2. The cast slurry is degassed, cast into shape, dried, and stamped to obtain a blank. S3. After debinding the blank, calcine it at 1350℃ for 25 minutes under a nitrogen atmosphere to obtain a high-strength, low-dielectric-constant ceramic substrate.

[0043] Experimental Example 1 The high-strength, low-dielectric-constant ceramic substrates prepared in Examples 1-10 and Comparative Examples 1-6 were subjected to dielectric constant testing according to the methods in GB / T5594.4-2015 "Test Methods for Performance of Structural Ceramic Materials for Electronic Components Part 4: Test Methods for Dielectric Constant and Dielectric Loss Tangent". The test conditions were 10 GHz and 20 °C. The test results are shown in Table 1. Table 1. Dielectric constant test results

[0044] Compared with Comparative Examples 1-6, the dielectric constant of the high-strength, low-dielectric-constant ceramic substrates prepared in Examples 1-10 was reduced, indicating that doping zinc silicate with cobalt suboxide to obtain doped zinc silicate and adding the doped zinc silicate to the ceramic substrate can effectively reduce the dielectric constant of the ceramic substrate.

[0045] Experimental Example 2 The high-strength, low-dielectric-constant ceramic substrates prepared in Examples 5 and 7-10 were tested for bending strength according to the test method specified in GB / T 6569-2006 "Test Method for Bending Strength of Fine Ceramics". The test method used was three-point bending. The test results are shown in Table 2. Table 2 Bending strength test results

[0046] In Table 2, compared with Examples 5 and 10, the bending strength of the high-strength, low-dielectric-constant ceramic substrates prepared in Examples 7-9 is improved. This indicates that the introduction of mullite microspheres into the ceramic substrate and the pre-mixing of mullite microspheres with alumina before mixing with other components during the preparation of the ceramic substrate can improve the bending strength of the ceramic substrate to a certain extent.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-strength, low-dielectric-constant ceramic substrate, characterized in that, The raw materials consist of the following components in parts by weight: 90 parts alumina, 9-15 parts doped zinc silicate, 4-6 parts sintering aid, 4-6 parts dispersant, 6-8 parts binder, and 60 parts solvent; The method for preparing the doped zinc silicate includes: Zinc silicate and cobalt oxide are mixed evenly, ball-milled, calcined, and pulverized to obtain the doped zinc silicate.

2. The high-strength, low-dielectric-constant ceramic substrate according to claim 1, characterized in that, The weight ratio of zinc silicate to cobalt oxide is 10:1~3.

3. The high-strength, low-dielectric-constant ceramic substrate according to claim 1, characterized in that, During ball milling, the milling speed is 200-300 rpm and the milling time is 20-40 min.

4. The high-strength, low-dielectric-constant ceramic substrate according to claim 1, characterized in that, During the calcination, the calcination temperature is 1050~1100℃ under a nitrogen atmosphere, and the calcination time is 1~2h.

5. A high-strength, low-dielectric-constant ceramic substrate according to claim 1, characterized in that, The particle size of the doped zinc silicate is 50~80μm.

6. A high-strength, low-dielectric-constant ceramic substrate according to claim 1, characterized in that, The raw materials also include mullite microspheres, and the amount of mullite microspheres added is 5% to 9% of the weight of the alumina.

7. A high-strength, low-dielectric-constant ceramic substrate according to claim 1, characterized in that, The sintering aid includes one or both of Y2O3 and MgO.

8. A high-strength, low-dielectric-constant ceramic substrate according to claim 1, characterized in that, The dispersant includes one or both of triethyl phosphate and tributyl phosphate.

9. A high-strength, low-dielectric-constant ceramic substrate according to claim 1, characterized in that, The adhesive includes polyvinyl butyral; The solvent includes one or both of ethanol and acetone.

10. A method for preparing a high-strength, low-dielectric-constant ceramic substrate, used to prepare a high-strength, low-dielectric-constant ceramic substrate as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Mix all components evenly and ball mill to obtain cast slurry; S2. The cast slurry is degassed, cast into shape, dried, and stamped to obtain a blank. S3. The blank is debonded and calcined to obtain the high-strength, low-dielectric-constant ceramic substrate.

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