Aluminum nitride ceramic slurry for tape casting, aluminum nitride ceramic and preparation method of aluminum nitride ceramic slurry

Abstract

The invention discloses aluminum nitride ceramic slurry for tape casting, aluminum nitride ceramic and a preparation method of the aluminum nitride ceramic, and belongs to the technical field of ceramic tape casting. The aluminum nitride ceramic slurry for tape casting comprises the following raw materials: 75-85 parts of aluminum nitride, 1-4 parts of a sintering aid, 10-20 parts of a plasticizer, 30-40 parts of a binder, 5-10 parts of an inert material, 5-10 parts of a solvent and 2-3 parts of a dispersant. In addition, the invention also provides a preparation method of the aluminum nitride ceramic slurry, which comprises the following steps: dissolving the plasticizer, the inert material, the binder and the dispersant in the solvent to prepare a premixed solution; and adding aluminum nitride ceramic powder and a sintering aid into the premixed liquid, and then grinding to obtain the ceramic slurry. In addition, the invention also provides a preparation method of the aluminum nitride ceramic. According to the aluminum nitride ceramic slurry provided by the invention, the generation of defects in a PVB degreasing process is greatly reduced, and the mechanical and thermal properties of aluminum nitride ceramic subjected to tape casting are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic tape casting, and particularly relates to an aluminum nitride ceramic slurry for tape casting, an aluminum nitride ceramic, and a preparation method thereof. Background Art

[0002] Aluminum nitride substrates are a kind of high-performance ceramic substrate materials, which have been widely used in the electronics industry due to their excellent physical and chemical properties. The main characteristics of aluminum nitride substrates include high thermal conductivity, low coefficient of thermal expansion, high electrical insulation, high resistivity, high temperature resistance, chemical corrosion resistance, and good light transmittance. These characteristics make aluminum nitride substrates an ideal choice for high-power and high-temperature applications, especially suitable for applications such as high-power LEDs and chip resistors. Aluminum nitride ceramic substrates have high thermal conductivity, which is beneficial to heat dissipation, can effectively reduce the thermal resistance, and improve the heat dissipation performance; aluminum nitride ceramic substrates have good corrosion resistance and can be used in applications under acid-base and high-pressure environments; the linear expansion coefficient of aluminum nitride ceramic substrates is very low, and they can still maintain good dimensional stability at high temperatures and are not easily deformed; there is a relatively tight bonding force between the aluminum nitride ceramic substrate and the metal layer, and the bonding strength between the metal layer and the ceramic is high, which has great application advantages; aluminum nitride ceramic substrates have the characteristics of low high-frequency loss and small dielectric constant, can be used for the design and assembly of high-frequency circuits, and can also be used for high-density assembly. The line / space (L / S) resolution can reach 20 μm. In the current technological trend of being thin, light, small, and compact, it is very conducive to realizing the short, small, light, and thin of equipment. Due to the above advantages of aluminum nitride ceramic substrates, they are widely used in fields such as aerospace, communication information, lighting, and household appliances.

[0003] The most suitable forming method for preparing high-performance aluminum nitride ceramic substrates is tape casting. The raw material for tape casting is aluminum nitride ceramic slurry. Aluminum nitride ceramic slurry is usually composed of aluminum nitride ceramic powder, sintering aid powder, binder, plasticizer, solvent, dispersant, etc. Among them, the sintering system consists of aluminum nitride ceramic powder and sintering aid powder. The binder is usually polyvinyl butyral (abbreviated as PVB), polyvinyl alcohol (abbreviated as PVA), etc. In the tape casting ceramic slurry system, PVB usually accounts for about 80wt% of the organic components, and the other 20wt% is usually the plasticizer. Common plasticizers include polyethylene glycol, polypropylene glycol, dibutyl phthalate, etc. The solvent is usually ethanol, acetone, toluene, etc. Since the solvent will volatilize during the tape casting process, it is not included in the organic system of the green body. The main steps for tape casting aluminum nitride ceramic substrates are as follows: ① Prepare aluminum nitride ceramic slurry; ② Tape cast a single layer of aluminum nitride; ③ Warm isostatic pressing for lamination and cutting to form a green body; ④ Debinding of the aluminum nitride ceramic green body; ⑤ High-temperature sintering to achieve densification of the aluminum nitride ceramic substrate. However, the organic system mainly composed of binder and plasticizer in the aluminum nitride ceramic green body usually accounts for 15-20wt%. Moreover, macromolecules such as PVB have a high decomposition temperature, and heat accumulates severely during decomposition, resulting in a large number of defects being easily generated during the debinding process. As a result, there are still a large number of defects inside the aluminum nitride ceramic substrate after final sintering, seriously damaging the performance of the aluminum nitride ceramic substrate. Debinding is usually completed in a low-temperature furnace, with the debinding temperature ranging from 25 to 800°C and the debinding rate being 0.1-0.5°C / min. The extremely low debinding rate leads to an overly long debinding cycle, seriously affecting the processing efficiency of the aluminum nitride ceramic substrate. Therefore, during the process of tape casting aluminum nitride ceramics, the thermal debinding process not only affects the performance of the tape-cast aluminum nitride substrate but is also crucial for improving the production efficiency of the aluminum nitride ceramic substrate.

[0004] Difficulties in debinding, long debinding cycles, and easy generation of defects during the debinding process in tape casting aluminum nitride can all lead to poor mechanical and thermal properties of aluminum nitride ceramics. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies, provide an aluminum nitride ceramic slurry for tape casting, an aluminum nitride ceramic, and its preparation method, and solve the technical problem of easy generation of defects during the debinding process of tape casting aluminum nitride in the prior art.

[0006] In order to achieve the above technical objectives, the technical solution of the present invention provides an aluminum nitride ceramic slurry for tape casting, and the raw materials are calculated by weight and include: 75-85 parts of aluminum nitride, 1-4 parts of sintering aid, 10-20 parts of plasticizer, 30-40 parts of binder, 5-10 parts of inert material, 5-10 parts of solvent and 2-3 parts of dispersant; the plasticizer is one or more of PEG200, PEG300 and PPG200; the inert material is one or more of oleic acid, small molecule paraffin and stearic acid.

[0007] In any embodiment, the sintering aid is one or more of Y2O3, YF2, Sm2O3 and SmF2; and / or, the binder is one or both of polyvinyl butyral and polyvinyl alcohol.

[0008] In any embodiment, the dispersant is one or more of BYK111, BYK180, BYK163, Sago9900 and Sago9780.

[0009] In any embodiment, the solvent is one or more of ethanol, toluene and acetone.

[0010] In addition, the present invention also provides a method for preparing the aluminum nitride ceramic slurry for tape casting, comprising the following steps:

[0011] Dissolving a plasticizer, an inert material, a binder and a dispersant in a solvent to prepare a premixed liquid;

[0012] Aluminum nitride ceramic powder and sintering aid are added to the premixed liquid, and then ground to obtain ceramic slurry.

[0013] In addition, the present invention also provides an aluminum nitride ceramic green body, which is obtained by the ceramic slurry obtained by the above preparation method or by tape casting of the above ceramic slurry.

[0014] In addition, the present invention also provides a method for preparing aluminum nitride ceramics, comprising the following steps:

[0015] The aluminum nitride ceramic green body is solvent degreased at 50-100°C, then heated from 25-30°C to 950-1000°C at a heating rate of 0.5-1.0°C / min for thermal degreasing, and then sintered at 1850-2000°C to obtain the aluminum nitride ceramic.

[0016] In any embodiment, the solvent degreasing time is 4-8 hours; and / or the sintering time is 4-10 hours.

[0017] In any embodiment, the atmosphere of the thermal debinding is nitrogen, and during the thermal debinding, the temperature is kept at 300-400° C. for 2-3 hours.

[0018] In addition, the present invention also provides an aluminum nitride ceramic prepared by the above preparation method.

[0019] Compared with the prior art, the beneficial effects of the present invention include: the present invention improves on the basis of traditional aluminum nitride ceramic slurries. First, plasticizers with small molecular weights are selected, such as polyethylene glycol 200 and polypropylene glycol 200, etc. At the same time, low-molecular paraffin, oleic acid, stearic acid and other inert small molecules are added to the plasticizer. These small-molecular-weight plasticizers and inert small molecules can all dissolve in common solvents such as acetone and ethanol, and can achieve low-temperature solvent debinding, laying a foundation for the successful and smooth removal of macromolecules such as the subsequent binder PVB. The aluminum nitride ceramic slurry is prepared into an aluminum nitride ceramic green body by tape casting. The small-molecule organic substances in the green body can be removed first through solvent debinding. Subsequently, the ceramic green body after removing the small-molecule organic substances presents a porous microstructure. These porous microstructures can provide diffusion channels for the thermal degradation and product overflow of macromolecular organic substances such as PVB, greatly reducing the defects generated during the PVB debinding process and improving the mechanical and thermal properties of the tape-cast aluminum nitride ceramic. Brief Description of the Drawings

[0020] Figure 1 It is the TG / DSC analysis result diagram of Example 1 of the present invention.

[0021] Figure 2 It is the TG / DSC analysis result diagram of Comparative Example 1 of the present invention.

[0022] Figure 3 It is the flexural strength and thermal conductivity results of Examples 1-3 and Comparative Examples 1-2 of the present invention. Detailed Description of the Invention

[0023] The "ranges" disclosed in this application are defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of a particular range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, ranges of 60 to 110 and 80 to 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise specified, the numerical range "a to b" represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" are fully listed herein, and "0 to 5" is only an abbreviated representation of these numerical combinations. Additionally, when a parameter is stated as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0024] Unless otherwise specified, the terms "comprising" and "including" mentioned in this application are open-ended and can also be closed-ended. For example, the said "comprising" and "including" can mean that other components not listed can also be included or comprised, or it can only include or comprise the listed components.

[0025] Unless otherwise specified, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) while B is true (or exists); or both A and B are true (or exist).

[0026] The present specific embodiment provides an aluminum nitride ceramic slurry for tape casting, wherein the raw materials are calculated by weight and include: 75-85 parts of aluminum nitride, 1-4 parts of sintering aid, 10-20 parts of plasticizer, 30-40 parts of binder, 5-10 parts of inert material, 5-10 parts of solvent and 2-3 parts of dispersant; the plasticizer is one or more of PEG200, PEG300 and PPG200; the inert material is one or more of oleic acid, small molecule paraffin and stearic acid; the sintering aid is one or more of Y2O3, YF2, Sm2O3 and SmF2; the dispersant is one or more of BYK111, BYK180, BYK163, Sago9900 and Sago9780; the solvent is one or more of ethanol, toluene and acetone; the binder is one or two of polyvinyl butyral PVB and polyvinyl alcohol PVA. It should be noted that the number of carbon atoms of normal alkanes in small molecule paraffin is 18 to 20.

[0027] In addition, this specific embodiment also proposes a method for preparing the above-mentioned aluminum nitride ceramic slurry for tape casting, comprising the following steps:

[0028] Dissolving a plasticizer, an inert material, a binder and a dispersant in a solvent to prepare a premixed liquid;

[0029] Aluminum nitride ceramic powder and sintering aid are added to the premixed liquid, and then ground to obtain ceramic slurry.

[0030] In addition, this specific embodiment also proposes an aluminum nitride ceramic green body, which is obtained by the ceramic slurry obtained by the above preparation method or by tape casting of the above ceramic slurry.

[0031] In addition, this specific embodiment also proposes a method for preparing aluminum nitride ceramics, comprising the following steps:

[0032] The aluminum nitride ceramic green body is subjected to solvent degreasing at 50-100°C for 4-8h, then thermally degreasing is performed by heating the green body from 25-30°C to 950-1000°C at a heating rate of 0.5-1.0°C / min, and then sintering is performed at 1850-2000°C for 4-10h to obtain the aluminum nitride ceramic; the atmosphere of the thermal degreasing is nitrogen, and during the thermal degreasing, the temperature is kept at 300-400°C for 2-3h.

[0033] This specific implementation also provides an aluminum nitride ceramic, which is prepared by the above preparation method.

[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] In the present invention, reference is made to "some embodiments", "this embodiment", and examples, etc., which describe subsets of all possible embodiments. However, it is understood that "some embodiments" can be the same subset or different subsets of all possible embodiments, and can be combined with each other without conflict.

[0036] If similar descriptions such as "first / second" appear in the application documents, the following explanations shall be added. In the following descriptions, the terms "first / second / third" only distinguish similar objects and do not represent a specific order for the objects. It is understood that "first / second / third" can be interchanged with a specific order or sequence when permitted, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0037] In this embodiment, the term "and / or" is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, object A and / or object B can represent three situations: the individual existence of object A, the simultaneous existence of object A and object B, and the individual existence of object B.

[0038] The following describes the embodiments of the present application. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. For those technical or conditions not specified in the embodiments, they shall be carried out according to the techniques or conditions described in the literature in the art or according to the product specifications. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase. The specific implementation means of tape casting in the following embodiments or comparative examples come from the prior art and will not be elaborated hereinafter.

[0039] In the following embodiments or comparative examples, the tape casting temperature is 80 °C, the tape speed is 50 mm / s, and the tape thickness is 200 μm to obtain a single-layer aluminum nitride thin film.

[0040] Embodiment 1

[0041] This embodiment provides an aluminum nitride ceramic slurry for tape casting. Calculated by mass fraction, the raw materials include: 80 parts of aluminum nitride, 2 parts of sintering aid Y2O3, 20 parts of plasticizer PEG200, 35 parts of binder polyvinyl butyral, 5 parts of inert material small molecule paraffin, 5 parts of solvent, and 2 parts of dispersant BYK111; the solvent is a mixture of ethanol and acetone, and the volume ratio of ethanol to acetone is 1:1.

[0042] This embodiment also provides a preparation method for the above-mentioned aluminum nitride ceramic slurry for tape casting, including the following steps:

[0043] Dissolve the plasticizer, inert material, binder, and dispersant in the solvent to obtain a premixed solution;

[0044] Aluminum nitride ceramic powder and sintering aid are added to the premixed liquid, and then ground to obtain ceramic slurry.

[0045] In addition, this embodiment also provides an aluminum nitride ceramic green body, which is produced by tape casting of the above ceramic slurry.

[0046] In addition, this embodiment also provides a method for preparing aluminum nitride ceramics, comprising the following steps:

[0047] The aluminum nitride ceramic green body was solvent degreased at 50°C for 8 hours, then thermally degreased by heating from 30°C to 950°C at a heating rate of 0.5°C / min, and then sintered at 1850°C for 10 hours to obtain the aluminum nitride ceramic; the atmosphere of the thermal degreasing was nitrogen, and during the thermal degreasing, the temperature was kept at 300°C for 3 hours.

[0048] Example 2

[0049] This embodiment proposes an aluminum nitride ceramic slurry for tape casting. The raw materials, calculated by mass, include: 75 parts of aluminum nitride, 4 parts of sintering aid YF2, 15 parts of plasticizer PEG200, 30 parts of binder polyvinyl butyral, 8 parts of inert material oleic acid, 10 parts of solvent ethanol and 3 parts of dispersant Sago9900; the solvent is a mixed solvent of ethanol and acetone, and the volume ratio of ethanol to acetone is 3:1.

[0050] This embodiment also provides a method for preparing the aluminum nitride ceramic slurry for tape casting, comprising the following steps:

[0051] Dissolving a plasticizer, an inert material, a binder and a dispersant in a solvent to prepare a premixed liquid;

[0052] Aluminum nitride ceramic powder and sintering aid are added to the premixed liquid, and then ground to obtain ceramic slurry.

[0053] In addition, this embodiment also provides an aluminum nitride ceramic green body, which is produced by tape casting of the above ceramic slurry.

[0054] In addition, this embodiment also provides a method for preparing aluminum nitride ceramics, comprising the following steps:

[0055] The aluminum nitride ceramic green body was solvent degreased at 80°C for 6 hours, then thermally degreased by heating from 25°C to 1000°C at a heating rate of 1.0°C / min, and then sintered at 1900°C for 8 hours to obtain the aluminum nitride ceramic; the atmosphere of the thermal degreasing was nitrogen, and during the thermal degreasing, the temperature was kept at 350°C for 2 hours.

[0056] Example 3

[0057] This embodiment provides an aluminum nitride ceramic slurry for tape casting. The raw materials are calculated by mass fraction and include: 85 parts of aluminum nitride, 1 part of sintering aid SmF2, 10 parts of plasticizer PPG200, 40 parts of binder polyvinyl alcohol, 10 parts of inert material stearic acid, 8 parts of solvent toluene, and 2 parts of dispersant BYK180.

[0058] This embodiment also provides a preparation method for the above-mentioned aluminum nitride ceramic slurry for tape casting, including the following steps:

[0059] Dissolve the plasticizer, inert material, binder, and dispersant in the solvent to obtain a premixed solution;

[0060] Add the aluminum nitride ceramic powder and sintering aid to the premixed solution, and then grind to obtain the ceramic slurry.

[0061] In addition, this embodiment also provides an aluminum nitride ceramic green body, which is obtained by tape casting the above-mentioned ceramic slurry.

[0062] In addition, this embodiment also provides a preparation method for aluminum nitride ceramics, including the following steps:

[0063] Carry out solvent debinding on the above-mentioned aluminum nitride ceramic green body at 100 °C for 4 h, then heat debind from 25 °C to 1000 °C at a heating rate of 0.8 °C / min, and then sinter at 2000 °C for 4 h to obtain the aluminum nitride ceramic; the atmosphere for heat debinding is nitrogen, and during heat debinding, hold at 400 °C for 2.5 h.

[0064] Comparative Example 1

[0065] The difference between this comparative example and Example 1 is that the aluminum nitride ceramic slurry for tape casting does not contain inert material, and an equal amount of solvent acetone is used to replace the amount of inert material.

[0066] The preparation method for the aluminum nitride ceramic slurry for tape casting in this comparative example includes the following steps:

[0067] Dissolve the plasticizer, binder, and dispersant in the solvent to obtain a premixed solution;

[0068] Add the aluminum nitride ceramic powder and sintering aid to the premixed solution, and then grind to obtain the ceramic slurry.

[0069] The preparation methods for the aluminum nitride ceramic green body and aluminum nitride ceramics are the same as those in Example 1.

[0070] Comparative Example 2

[0071] The aluminum nitride ceramic slurry for tape casting in this comparative example is the same as that in Example 1.

[0072] The difference between this comparative example and Example 1 lies in that in the preparation method of aluminum nitride ceramics, solvent debinding was not carried out, but direct thermal debinding was performed. Specifically, the green body of the prepared aluminum nitride ceramics was heated from 25 °C to 1000 °C at a heating rate of 1.0 °C / min for thermal debinding, and then sintered at 1900 °C for 8 h to obtain the aluminum nitride ceramics; the atmosphere for the thermal debinding was nitrogen, and during the thermal debinding, it was held at 350 °C for 2 h.

[0073] From Figure 1 and Figure 2 it can be seen that Figure 1 in Example 1, the endothermic process is stable and the endothermic peak is close to 0. Figure 2 In Comparative Example 1, there are multiple endothermic peaks, the entire debinding process is unstable, the heat is concentrated, and defects are extremely likely to occur.

[0074] The mechanical properties and thermal properties of the aluminum nitride ceramics prepared in Examples 1-3 and Comparative Examples 1-2 were tested according to the standard GB / T 3962-2017, and the results are as Figure 3 shown. The flexural strength of the aluminum nitride ceramics in Examples 1-3 can be as high as over 320 MPa, and the thermal conductivity can be as high as over 230 W / (m·K). The flexural strength of the aluminum nitride ceramics in Comparative Example 1 and Comparative Example 2 is as low as below 100 MPa, and the thermal conductivity is as low as 130 W / (m·K).

[0075] The specific embodiments of the present invention described above do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. An aluminum nitride ceramic slurry for tape casting, characterized in that, The raw materials, calculated by mass parts, include: 75 - 85 parts of aluminum nitride, 1 - 4 parts of sintering aid, 10 - 20 parts of plasticizer, 30 - 40 parts of binder, 5 - 10 parts of inert material, 5 - 10 parts of solvent, and 2 - 3 parts of dispersant; the plasticizer is one or more of PEG200, PEG300, and PPG200; the inert material is one or more of oleic acid, small molecule paraffin, and stearic acid.

2. The aluminum nitride ceramic slurry for tape casting according to claim 1, wherein The sintering aid is one or more of Y2O3, YF2, Sm2O3, and SmF2; and / or, the binder is one or two of polyvinyl butyral and polyvinyl alcohol.

3. The aluminum nitride ceramic slurry for tape casting according to claim 1, wherein The dispersant is one or more of BYK111, BYK180, BYK163, Sago9900, and Sago9780.

4. The aluminum nitride ceramic slurry for tape casting according to claim 1, characterized in that, The solvent is one or more of ethanol, toluene, and acetone.

5. A method for preparing an aluminum nitride ceramic slurry for tape casting according to any one of claims 1-4, characterized in that, It includes the following steps: Dissolve the plasticizer, inert material, binder, and dispersant in the solvent to obtain a premixed solution; Add the aluminum nitride ceramic powder and sintering aid to the premixed solution, and then grind to obtain a ceramic slurry.

6. A green body of aluminum nitride ceramic, characterized in that, It is obtained by tape casting of the ceramic slurry prepared by the preparation method according to any one of claims 1 - 4 or the ceramic slurry according to claim 5.

7. A method for preparing aluminum nitride ceramics, characterized in that, It includes the following steps: Perform solvent debinding on the green body of aluminum nitride ceramic according to claim 6 at 50 - 100 °C, then heat up from 25 - 30 °C to 950 - 1000 °C at a heating rate of 0.5 - 1.0 °C / min for thermal debinding, and then sinter at 1850 - 2000 °C to obtain the aluminum nitride ceramic.

8. The preparation method of aluminum nitride ceramic according to claim 7, characterized in that, The time for solvent debinding is 4 - 8 h; and / or, the time for sintering is 4 - 10 h.

9. The preparation method of aluminum nitride ceramic according to claim 7, characterized in that, The atmosphere for thermal debinding is nitrogen, and during thermal debinding, keep it at 300 - 400 °C for 2 - 3 h.

10. An aluminum nitride ceramic, characterized in that, It is obtained by the preparation method according to any one of claims 7 - 9.

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