Preparation method of aluminum nitride ceramic aluminum-coated plate and aluminum nitride ceramic aluminum-coated plate

Abstract

The invention provides a preparation method of an aluminum nitride ceramic aluminum-coated plate and the aluminum nitride ceramic aluminum-coated plate, and relates to the technical field of ceramic materials. The preparation method comprises the following steps: cleaning an aluminum nitride substrate for multiple times, and cleaning an aluminum foil for multiple times; coating the bonding area of the aluminum nitride substrate with an aluminum-based brazing material; wherein alloy powder in the aluminum-based brazing material comprises Al and Si; and the side, coated with the aluminum-based brazing material, of the aluminum nitride substrate and aluminum foil are stacked together and then subjected to brazing heat treatment, and the aluminum nitride ceramic aluminum-coated plate is obtained. According to the invention, the problem of poor wettability of aluminum and the aluminum nitride ceramic surface can be solved, and effective bonding of aluminum nitride and the aluminum foil is realized at a relatively low temperature.

Description

Technical Field

[0001] The present disclosure relates to the technical field of ceramic materials, and in particular to a method for preparing an aluminum nitride ceramic aluminum-coated plate and an aluminum nitride ceramic aluminum-coated plate. Background Art

[0002] The rapid development and widespread application of power semiconductor devices, especially high-voltage and high-current IGBT modules, have put forward higher requirements for ceramic linings in packaging materials. Aluminum nitride substrates have the advantages of high thermal conductivity and a thermal expansion coefficient close to that of Si, and are very promising packaging substrate materials. Since aluminum nitride is a compound with strong covalent bonds, general solder cannot wet the surface of aluminum nitride ceramics. To achieve reliable connection between aluminum nitride and electronic chips, it is usually necessary to metallize the surface of aluminum nitride ceramics.

[0003] The most commonly used aluminum nitride metallization method is aluminum nitride copper clad, but the disadvantage of aluminum nitride copper clad laminates' poor resistance to thermal shock seriously restricts its application. The yield limit of aluminum is very low, which is conducive to the release of thermal stress. Aluminum nitride ceramic aluminum clad laminates have better thermal cycle shock performance.

[0004] At present, the preparation process of aluminum nitride ceramic aluminum-coated plates has the problem that the wettability of aluminum on the surface of aluminum nitride ceramics is poor at low temperatures and effective bonding cannot be formed.

[0005] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0006] The purpose of the present disclosure is to provide a method for preparing an aluminum nitride ceramic aluminum-clad plate and an aluminum nitride ceramic aluminum-clad plate, thereby overcoming the problem of poor bonding performance between aluminum nitride and aluminum foil at least to a certain extent.

[0007] According to a first aspect of the present disclosure, a method for preparing an aluminum nitride ceramic aluminum-clad plate is provided, comprising: performing multiple cleaning processes on an aluminum nitride substrate and multiple cleaning processes on an aluminum foil; coating an aluminum-based brazing material on a bonding area of ​​the aluminum nitride substrate; wherein the alloy powder in the aluminum-based brazing material contains Al and Si; and stacking a side of the aluminum nitride substrate coated with the aluminum-based brazing material with the aluminum foil and then performing a brazing heat treatment to obtain an aluminum nitride ceramic aluminum-clad plate.

[0008] Optionally, performing multiple cleaning processes on the aluminum nitride substrate includes: performing multiple ultrasonic cleaning processes on the aluminum nitride substrate using sodium hydroxide solution, alcohol and pure water respectively.

[0009] Optionally, the mass fraction of the sodium hydroxide solution is 5% to 8%, and the time for ultrasonic cleaning using the sodium hydroxide solution is 15 minutes to 40 minutes; the time for ultrasonic cleaning using alcohol is 10 minutes to 15 minutes; and the time for ultrasonic cleaning using pure water is 10 minutes to 15 minutes.

[0010] Optionally, performing multiple cleaning processes on the aluminum foil includes: performing multiple ultrasonic cleaning processes on the aluminum foil using sodium hydroxide solution, alcohol and pure water respectively.

[0011] Optionally, the mass fraction of the sodium hydroxide solution is 1% to 2%, and the time for ultrasonic cleaning using the sodium hydroxide solution is 2 min to 10 min; the time for ultrasonic cleaning using alcohol is 10 min to 15 min; and the time for ultrasonic cleaning using pure water is 10 min to 15 min.

[0012] Optionally, the mole percentage of Si in the aluminum-based brazing material is 6% to 12%.

[0013] Optionally, the brazing heat treatment includes a first heat treatment process and a second heat treatment process, and the temperature in the first heat treatment process is lower than the temperature in the second heat treatment process.

[0014] Optionally, the first heat treatment process includes heating the temperature to 300°C to 350°C at a heating rate of 3°C / min to 10°C / min, and keeping it warm for 10 to 30 minutes; the second heat treatment process includes heating the temperature to 580°C to 650°C at a heating rate of 3°C / min to 10°C / min, and keeping it warm for 10 to 60 minutes.

[0015] Optionally, the atmosphere of the brazing heat treatment is nitrogen or argon.

[0016] According to a second aspect of the present disclosure, there is provided an aluminum nitride ceramic aluminum-clad plate, which is prepared by any of the above-mentioned methods for preparing an aluminum nitride ceramic aluminum-clad plate.

[0017] In the scheme of the exemplary embodiment of the present disclosure, on the one hand, by adding aluminum-based brazing materials to form an Al-Si eutectic liquid phase, the problem of poor wettability between aluminum and aluminum nitride ceramic surfaces is solved, and effective bonding of aluminum nitride and aluminum foil is achieved at a lower temperature. On the other hand, the preparation process disclosed in the present disclosure is simple to operate, does not require modification of the aluminum nitride ceramic surface, is easy to industrially produce, and saves time.

[0018] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0020] Figure 1 The flowchart of the method for preparing the aluminum nitride ceramic aluminum-clad plate according to an exemplary embodiment of the present disclosure is schematically shown.

[0021] Figure 2 The metallographic image of the aluminum nitride ceramic aluminum-clad plate prepared in Example 1 of the present disclosure is shown. DETAILED DESCRIPTION

[0022] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as being limited to the examples set forth herein; on the contrary, these embodiments are provided so that the present disclosure will be more comprehensive and complete, and the concepts of the example embodiments are fully conveyed to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced while omitting one or more of the specific details, or other methods, processes, steps, etc. may be adopted. In other cases, known technical solutions are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

[0023] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated descriptions will be omitted. The flowcharts shown in the accompanying drawings are only exemplary illustrations and do not necessarily include all the steps. For example, some steps can also be decomposed, while some steps can be combined or partially combined, so the actual execution order may change according to actual conditions. In addition, all the terms "first", "second", etc. below are only for the purpose of distinction and should not be used as limitations of the present disclosure.

[0024] At present, the preparation scheme of aluminum nitride ceramic aluminum-coated plate has the following problems: First, at low temperatures, the wettability of aluminum on the surface of aluminum nitride ceramic is poor and cannot form an effective bond. When the temperature is higher than 950°C, the wettability of aluminum on the surface of aluminum nitride ceramic is enhanced, but at this time the temperature is much higher than the melting point of aluminum, and it is difficult to form aluminum foil on the surface of aluminum nitride ceramic. Second, aluminum is very easy to oxidize and form a dense oxide film on the surface, which greatly reduces the wettability of aluminum liquid and ceramic and seriously hinders the bonding of aluminum and aluminum nitride.

[0025] There are two main technologies for coating ceramics with aluminum. One is to directly use aluminum liquid to physically wet the ceramic substrate, that is, to cast or die-cast the high-temperature aluminum liquid on the ceramic substrate. This method has high requirements for the mold and the melt processing process. In addition, since the aluminum layer formed after pouring aluminum liquid on the ceramic substrate may have problems such as irregular shape and uneven thickness, secondary processing is required after demolding, which is costly. The other is to use sputtering and other processes to pre-treat the surface of the ceramic. The sputtering equipment of this method is expensive and not suitable for mass production.

[0026] In view of this, the embodiments of the present disclosure provide a method for preparing a new aluminum nitride ceramic aluminum-clad plate which has relatively low cost and can solve the bonding problem between aluminum and aluminum nitride.

[0027] Figure 1 The flowchart of the method for preparing the aluminum nitride ceramic aluminum-clad plate according to an exemplary embodiment of the present disclosure is schematically shown. Figure 1 The method for preparing the aluminum nitride ceramic aluminum-clad plate according to the embodiment of the present disclosure comprises the following steps:

[0028] S12. Perform multiple cleaning processes on the aluminum nitride substrate and multiple cleaning processes on the aluminum foil.

[0029] According to some embodiments of the present disclosure, the aluminum nitride substrate can be subjected to multiple ultrasonic cleaning processes using sodium hydroxide solution, alcohol, and pure water, respectively. The mass fraction of the sodium hydroxide solution is 5% to 8%, the ultrasonic cleaning time using the sodium hydroxide solution is 15 minutes to 40 minutes, the ultrasonic cleaning time using alcohol is 10 minutes to 15 minutes, and the ultrasonic cleaning time using pure water is 10 minutes to 15 minutes.

[0030] Similarly, the aluminum foil is subjected to multiple ultrasonic cleaning processes using sodium hydroxide solution, alcohol and pure water, respectively. The mass fraction of the sodium hydroxide solution is 1% to 2%, the ultrasonic cleaning time using the sodium hydroxide solution is 2 minutes to 10 minutes, the ultrasonic cleaning time using the alcohol is 10 minutes to 15 minutes, and the ultrasonic cleaning time using the pure water is 10 minutes to 15 minutes.

[0031] Through the above cleaning process, the influence of oxide film, impurities, etc. on the subsequent bonding process can be avoided, ensuring the high-quality forming of the aluminum nitride ceramic clad aluminum plate.

[0032] It is understood that after cleaning, a drying process, such as blow drying, may be performed to apply the clean aluminum nitride substrate and aluminum foil to the following process.

[0033] S14. Coating an aluminum-based brazing material on the bonding area of ​​the aluminum nitride substrate; wherein the alloy powder in the aluminum-based brazing material contains Al and Si.

[0034] In the exemplary embodiment of the present disclosure, the bonding area refers to an area on the aluminum nitride substrate to be bonded with aluminum, and the present disclosure does not limit its position on the aluminum nitride substrate.

[0035] In order to form an Al-Si eutectic liquid phase to solve or at least alleviate the problem of poor bonding performance, the embodiment of the present disclosure limits the content of Si in the aluminum-based brazing material. Specifically, the molar percentage of Si in the aluminum-based brazing material is 6% to 12%.

[0036] S16. Stacking one side of the aluminum nitride substrate coated with the aluminum-based brazing material with an aluminum foil and performing a brazing heat treatment to obtain an aluminum nitride ceramic aluminum-clad plate.

[0037] In an exemplary embodiment of the present disclosure, the brazing heat treatment may include a first heat treatment process and a second heat treatment process. The first heat treatment process is performed first, and then the second heat treatment process is performed. The temperature in the first heat treatment process is lower than the temperature in the second heat treatment process.

[0038] Specifically, the first heat treatment process may include heating the temperature to 300°C to 350°C at a heating rate of 3°C / min to 10°C / min, and keeping the temperature for 10min to 30min. The second heat treatment process may include heating the temperature to 580°C to 650°C at a heating rate of 3°C / min to 10°C / min, and keeping the temperature for 10min to 60min.

[0039] The atmosphere of the brazing heat treatment is nitrogen or argon. However, the present disclosure is not limited thereto, and the brazing heat treatment can also be performed in other inert gas atmospheres.

[0040] In the exemplary embodiment of the present disclosure, it is not necessary to be less than 10 -3 Pa high vacuum environment, low equipment cost.

[0041] The preparation scheme of the present disclosure is described below by way of examples.

[0042] Example 1

[0043] First, the aluminum nitride substrate and aluminum foil were ultrasonically cleaned in the order of sodium hydroxide solution, alcohol and pure water, and finally dried for use. The mass fraction of the sodium hydroxide solution used to clean the aluminum nitride substrate was 5%, and the ultrasonic time was 15 minutes. The mass fraction of the sodium hydroxide solution used to clean the aluminum foil was 1%, and the ultrasonic time was 2 minutes. The ultrasonic time of alcohol and pure water was 10 minutes.

[0044] Next, an aluminum-based brazing material is coated on the bonding area of ​​the aluminum nitride substrate, wherein the molar percentage of Si in the alloy powder in the aluminum-based brazing material is 8%.

[0045] Then, the aluminum nitride side coated with brazing material is stacked with aluminum foil and placed in a furnace for brazing to obtain an aluminum nitride ceramic aluminum-clad plate. The brazing heat treatment process includes: heating to 300°C at a heating rate of 10°C / min and keeping the temperature for 30 minutes, and then heating to 600°C and keeping the temperature for 30 minutes. The heat treatment atmosphere is nitrogen.

[0046] Figure 2 The metallographic image of the aluminum nitride ceramic aluminum-clad plate prepared in Example 1 of the present disclosure is shown. Figure 2 It can be seen that the aluminum nitride substrate and the aluminum foil in the aluminum nitride ceramic aluminum-clad plate prepared in Example 1 of the present disclosure are well combined, and there is no obvious gap at the interface.

[0047] Example 2

[0048] First, the aluminum nitride substrate and aluminum foil were ultrasonically cleaned in the order of sodium hydroxide solution, alcohol and pure water, and finally dried for use. The mass fraction of the sodium hydroxide solution used to clean the aluminum nitride substrate was 6%, and the ultrasonic time was 15 minutes. The mass fraction of the sodium hydroxide solution used to clean the aluminum foil was 2%, and the ultrasonic time was 10 minutes. The ultrasonic time of alcohol and pure water was 15 minutes.

[0049] Next, an aluminum-based brazing material is coated on the bonding area of ​​the aluminum nitride substrate, wherein the molar percentage of Si in the alloy powder in the aluminum-based brazing material is 6%.

[0050] Then, the aluminum nitride side coated with brazing material is stacked with aluminum foil and placed in a furnace for brazing to obtain an aluminum nitride ceramic aluminum-clad plate. The brazing heat treatment process includes: heating to 350°C at a heating rate of 3°C / min for 10 minutes, and then heating to 600°C for 60 minutes. The heat treatment atmosphere is nitrogen.

[0051] Example 3

[0052] First, the aluminum nitride substrate and aluminum foil were ultrasonically cleaned in the order of sodium hydroxide solution, alcohol and pure water, and finally dried for use. The mass fraction of the sodium hydroxide solution used to clean the aluminum nitride substrate was 8%, and the ultrasonic time was 40 minutes. The mass fraction of the sodium hydroxide solution used to clean the aluminum foil was 1%, and the ultrasonic time was 10 minutes. The ultrasonic time of alcohol and pure water was 12 minutes.

[0053] Next, an aluminum-based brazing material is coated on the bonding area of ​​the aluminum nitride substrate, wherein the molar percentage of Si in the alloy powder in the aluminum-based brazing material is 12%.

[0054] Then, the aluminum nitride side coated with brazing material is stacked with aluminum foil and placed in a furnace for brazing to obtain an aluminum nitride ceramic aluminum-clad plate. The brazing heat treatment process includes: heating to 300°C at a heating rate of 10°C / min for 30 minutes, and then heating to 580°C for 60 minutes. The heat treatment atmosphere is nitrogen.

[0055] Example 4

[0056] First, the aluminum nitride substrate and aluminum foil were ultrasonically cleaned in the order of sodium hydroxide solution, alcohol and pure water, and finally dried for use. The mass fraction of the sodium hydroxide solution used to clean the aluminum nitride substrate was 7%, and the ultrasonic time was 20 minutes. The mass fraction of the sodium hydroxide solution used to clean the aluminum foil was 1%, and the ultrasonic time was 5 minutes. The ultrasonic time of alcohol and pure water was 10 minutes.

[0057] Next, an aluminum-based brazing material is coated on the bonding area of ​​the aluminum nitride substrate, wherein the molar percentage of Si in the alloy powder in the aluminum-based brazing material is 6%.

[0058] Then, the aluminum nitride side coated with brazing material is stacked with aluminum foil and placed in a furnace for brazing to obtain an aluminum nitride ceramic aluminum-clad plate. The brazing heat treatment process includes: heating to 300°C at a heating rate of 10°C / min and keeping the temperature for 10 minutes, and then heating to 650°C and keeping the temperature for 10 minutes. The heat treatment atmosphere is nitrogen.

[0059] Example 5

[0060] First, the aluminum nitride substrate and aluminum foil were ultrasonically cleaned in the order of sodium hydroxide solution, alcohol and pure water, and finally dried for use. The mass fraction of the sodium hydroxide solution used to clean the aluminum nitride substrate was 5%, and the ultrasonic time was 15 minutes. The mass fraction of the sodium hydroxide solution used to clean the aluminum foil was 1%, and the ultrasonic time was 2 minutes. The ultrasonic time of alcohol and pure water was 10 minutes.

[0061] Next, an aluminum-based brazing material is coated on the bonding area of ​​the aluminum nitride substrate, wherein the molar percentage of Si in the alloy powder in the aluminum-based brazing material is 6%.

[0062] Then, the aluminum nitride side coated with brazing material is stacked with aluminum foil and placed in a furnace for brazing to obtain an aluminum nitride ceramic aluminum-clad plate. The brazing heat treatment process includes: heating to 300°C at a heating rate of 10°C / min and keeping the temperature for 10 minutes, and then heating to 600°C and keeping the temperature for 30 minutes. The heat treatment atmosphere is argon.

[0063] Furthermore, the embodiment of the present disclosure also provides an aluminum nitride ceramic aluminum-clad plate, which is prepared by the above-mentioned preparation method of the aluminum nitride ceramic aluminum-clad plate.

[0064] It should be noted that although the steps of the method in the present disclosure are described in a specific order in the drawings, this does not require or imply that the steps must be performed in this specific order, or that all the steps shown must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps, etc.

[0065] In addition, the above-mentioned figures are only schematic illustrations of the processes included in the method according to the exemplary embodiments of the present disclosure, and are not intended to be limiting. It is easy to understand that the processes shown in the above-mentioned figures do not indicate or limit the time sequence of these processes. In addition, it is also easy to understand that these processes can be performed synchronously or asynchronously, for example, in multiple modules.

[0066] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing what is disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary technical means in the art that are not disclosed in the present disclosure. The specification and embodiments are to be considered merely as exemplary, and the true scope and spirit of the present disclosure are indicated by the claims.

[0067] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A method for preparing an aluminum nitride ceramic aluminum-clad plate, characterized in that: include: The aluminum nitride substrate is subjected to multiple cleaning processes, and the aluminum foil is subjected to multiple cleaning processes; Coating an aluminum-based brazing material on the bonding area of ​​the aluminum nitride substrate; wherein the alloy powder in the aluminum-based brazing material contains Al and Si; The side of the aluminum nitride substrate coated with the aluminum-based brazing material is stacked with the aluminum foil and then subjected to brazing heat treatment to obtain an aluminum nitride ceramic aluminum-clad plate.

2. The preparation method according to claim 1, characterized in that: The multiple cleaning processes for aluminum nitride substrates include: The aluminum nitride substrate was ultrasonically cleaned multiple times using sodium hydroxide solution, alcohol and pure water respectively.

3. The preparation method according to claim 2, characterized in that: The mass fraction of the sodium hydroxide solution is 5% to 8%, and the time for ultrasonic cleaning using the sodium hydroxide solution is 15 minutes to 40 minutes; The time for ultrasonic cleaning using the alcohol is 10 to 15 minutes; The time for ultrasonic cleaning using pure water is 10 minutes to 15 minutes.

4. The preparation method according to claim 1, characterized in that: The multiple cleaning processes for aluminum foil include: The aluminum foil was ultrasonically cleaned multiple times using sodium hydroxide solution, alcohol and pure water respectively.

5. The preparation method according to claim 4, characterized in that: The mass fraction of the sodium hydroxide solution is 1% to 2%, and the time for ultrasonic cleaning using the sodium hydroxide solution is 2 minutes to 10 minutes; The time for ultrasonic cleaning using the alcohol is 10 to 15 minutes; The time for ultrasonic cleaning using pure water is 10 minutes to 15 minutes.

6. The preparation method according to claim 1, characterized in that: The molar percentage of Si in the aluminum-based brazing material is 6% to 12%.

7. The preparation method according to claim 1, characterized in that: The brazing heat treatment includes a first heat treatment process and a second heat treatment process, wherein the temperature in the first heat treatment process is lower than the temperature in the second heat treatment process.

8. The preparation method according to claim 7, characterized in that: The first heat treatment process comprises heating the temperature to 300°C to 350°C at a heating rate of 3°C / min to 10°C / min, and keeping the temperature for 10min to 30min; The second heat treatment process includes heating the temperature to 580° C. to 650° C. at a heating rate of 3° C. / min to 10° C. / min, and keeping the temperature for 10 min to 60 min.

9. The preparation method according to claim 1, 7 or 8, characterized in that: The atmosphere of the brazing heat treatment is nitrogen or argon.

10. An aluminum nitride ceramic aluminum-clad plate, characterized in that: The aluminum nitride ceramic aluminum-clad plate is prepared by the preparation method of any one of claims 1 to 9.

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