阅读说明：本技术 一种氮化铝陶瓷基板表面粗化方法 (Surface roughening method for aluminum nitride ceramic substrate ) 是由 王斌 贺贤汉 孙泉 欧阳鹏 葛荘 周轶靓 于 2020-04-26 设计创作，主要内容包括：本发明公开一种氮化铝陶瓷基板表面粗化方法,包括如下步骤：步骤一,通过除油剂和纯水去除氮化铝陶瓷基板表面的油污和杂质,测试氮化铝陶瓷基板的表面粗糙度,依据表面粗糙度的测试结果确定后续化学粗化程度；步骤二,将经步骤一处理过的氮化铝陶瓷基板浸没于15％-25％质量分数的NaOH溶液中；步骤三,将步骤二处理过的氮化铝陶瓷基板放置于1％-3％质量分数的稀H<Sub>2</Sub>SO<Sub>4</Sub>溶液中,处理5s-10s,温度控制在15℃-25℃；步骤四,将步骤三处理过的氮化铝陶瓷基板加压水洗,常温,时间为3min；步骤五,将步骤四处理过的氮化铝陶瓷基板烘干。有效解决现有AMB真空钎焊氮化铝陶瓷基板与焊料层结合不良的技术问题。(The invention discloses a surface roughening method for an aluminum nitride ceramic substrate, which comprises the following steps: removing oil stains and impurities on the surface of an aluminum nitride ceramic substrate through an oil removing agent and pure water, testing the surface roughness of the aluminum nitride ceramic substrate, and determining the subsequent chemical coarsening degree according to the test result of the surface roughness; step two, immersing the aluminum nitride ceramic substrate treated in the step one in a NaOH solution with the mass fraction of 15-25%; thirdly, placing the aluminum nitride ceramic substrate treated in the second step on 1-3% of diluted H in mass fraction 2 SO 4 Treating the mixture for 5-10 s in the solution, and controlling the temperature to be 15-25 ℃; step four, pressurizing and washing the aluminum nitride ceramic substrate treated in the step three for 3min at normal temperature; and step five, drying the aluminum nitride ceramic substrate treated in the step four. Effectively solves the technical problem that the existing AMB vacuum brazing aluminum nitride ceramic substrate is not well combined with a solder layer.)

1. A surface roughening method for an aluminum nitride ceramic substrate is characterized by comprising the following steps:

removing oil stains and impurities on the surface of an aluminum nitride ceramic substrate through an oil removing agent and pure water, testing the surface roughness of the aluminum nitride ceramic substrate, and determining the subsequent chemical coarsening degree according to the test result of the surface roughness;

immersing the aluminum nitride ceramic substrate treated in the step one in a NaOH solution with the mass fraction of 15% -25%, and carrying out ultrasonic treatment at 50 ℃ for 1min-4 min;

thirdly, placing the aluminum nitride ceramic substrate treated in the second step on 1-3% of diluted H in mass fraction₂SO₄Treating the mixture for 5-10 s in the solution, and controlling the temperature to be 15-25 ℃;

step four, pressurizing and washing the aluminum nitride ceramic substrate treated in the step three for 3min at normal temperature;

and step five, drying the aluminum nitride ceramic substrate processed in the step four, controlling the temperature to be 80-100 ℃ and the time to be 3-5 min.

2. The method according to claim 1, wherein the step of roughening the surface of the aluminum nitride ceramic substrate comprises: and fifthly, testing the surface roughness of the aluminum nitride ceramic substrate, wherein the surface roughness Ra of the aluminum nitride ceramic substrate is 0.3-0.4.

3. The method according to claim 1, wherein the step of roughening the surface of the aluminum nitride ceramic substrate comprises: and adjusting the concentration of the NaOH solution, the ultrasonic time and the treatment temperature in the second step to ensure that the surface roughness Ra of the aluminum nitride ceramic substrate after the fifth step is 0.3-0.4.

4. The method according to claim 1, wherein the step of roughening the surface of the aluminum nitride ceramic substrate comprises: when the tested surface roughness is 0.1-0.2 in the first step; the mass fraction of the NaOH solution in the second step is 20-25%, the temperature is 50 ℃, and the ultrasonic time is 3-4 min;

when the tested surface roughness is 0.2-0.25 in the first step; the mass fraction of the NaOH solution in the second step is 15-20%, the temperature is 50 ℃, and the ultrasonic time is 2-3 min;

when the tested surface roughness is 0.25-0.3 in the first step; and the mass fraction of the NaOH solution in the second step is 15-20%, the temperature is 50 ℃, and the ultrasonic time is 1-2 min.

5. The method according to claim 4, wherein the step of roughening the surface of the aluminum nitride ceramic substrate comprises: in the first step, the tested surface roughness is 0.1-0.17;

and (3) immersing the aluminum nitride ceramic wafer treated in the first step into a NaOH solution with the mass fraction of 20%, and performing ultrasonic treatment at 50 ℃ for 4 min.

6. The method according to claim 1, wherein the step of roughening the surface of the aluminum nitride ceramic substrate comprises: and the surface roughness is tested by selecting the front and back surfaces of at least 5 test points on the aluminum nitride ceramic substrate and taking the average value of the roughness of all the test points as a test result.

7. The method according to claim 6, wherein the step of roughening the surface of the aluminum nitride ceramic substrate comprises: all test points include a central point located at the center, and the rest of the test points are located at the periphery of the central point and close to the corners of the aluminum nitride ceramic substrate.

Technical Field

The invention relates to the technical field of surface treatment of ceramic substrates, in particular to a roughening method of a ceramic substrate.

Background

Aluminum nitride ceramic substrates have been widely used as liners for power modules of semiconductor devices due to their low dielectric constant, excellent thermal conductivity, and coefficient of thermal expansion matching the chip. When the metallization of the aluminum nitride ceramic substrate is realized by adopting an active metal brazing technology (AMB), active metal solder is required to be printed on the surface of the aluminum nitride ceramic substrate.

The direct bonding of the solder between the ceramic substrate and the copper foil after vacuum sintering has the problem of poor bonding between the AMB vacuum brazing aluminum nitride ceramic substrate and the solder layer.

Chemical roughening is one way to improve the adhesion of coatings. The chemical coarsening is essentially to carry out micro-etching on the surface of the ceramic, grooves and micropores are formed on the surface, and along with the increase of the chemical coarsening degree, the grooves and the micropores can form a microscopic network structure on the surface of the ceramic, and the structure can be mutually embedded with the coating to obviously improve the adhesive force of the coating, but when the chemical coarsening degree is too high, the structure can be damaged, and the adhesive force of the coating can be reduced. From this, it is known that the key to the chemical roughening technique is to control and evaluate the roughening degree.

At present, a roughening method suitable for an aluminum nitride ceramic substrate is lacked, so as to solve the technical problem that the conventional AMB vacuum brazing aluminum nitride ceramic substrate is not well combined with a solder layer.

Disclosure of Invention

In view of the problems in the prior art, the present invention provides a method for roughening a surface of an aluminum nitride ceramic substrate, which solves at least one of the above technical problems.

The technical scheme of the invention is as follows: a surface roughening method for an aluminum nitride ceramic substrate is characterized by comprising the following steps:

removing oil stains and impurities on the surface of an aluminum nitride ceramic substrate through an oil removing agent and pure water, testing the surface roughness of the aluminum nitride ceramic substrate, and determining the subsequent chemical coarsening degree according to the test result of the surface roughness;

immersing the aluminum nitride ceramic substrate treated in the step one in a NaOH solution with the mass fraction of 15% -25%, and carrying out ultrasonic treatment at 50 ℃ for 1min-4 min;

thirdly, placing the aluminum nitride ceramic substrate treated in the second step on 1-3% of diluted H in mass fraction₂SO₄Treating the mixture for 5-10 s in the solution, and controlling the temperature to be 15-25 ℃;

step four, pressurizing and washing the aluminum nitride ceramic substrate treated in the step three for 3min at normal temperature;

and step five, drying the aluminum nitride ceramic substrate processed in the step four, controlling the temperature to be 80-100 ℃ and the time to be 3-5 min.

Further preferably, after the fifth step, the surface roughness of the aluminum nitride ceramic substrate is tested, and the surface roughness Ra of the aluminum nitride ceramic substrate is 0.3-0.4. The tested aluminum nitride ceramic substrate has the surface roughness of 0.3-0.4 and the large peel strength.

Further preferably, the concentration of the NaOH solution, the ultrasonic time, and the treatment temperature in step two are adjusted to ensure that the surface roughness Ra of the aluminum nitride ceramic substrate after step five is 0.3 to 0.4.

Further preferably, when the surface roughness measured in the step one is 0.1 to 0.2; the mass fraction of the NaOH solution in the second step is 20-25%, the temperature is 50 ℃, and the ultrasonic time is 3-4 min;

when the tested surface roughness is 0.2-0.25 in the first step; the mass fraction of the NaOH solution in the second step is 15-20%, the temperature is 50 ℃, and the ultrasonic time is 2-3 min;

when the tested surface roughness is 0.25-0.3 in the first step; and the mass fraction of the NaOH solution in the second step is 15-20%, the temperature is 50 ℃, and the ultrasonic time is 1-2 min.

Further preferably, in the step one, the tested surface roughness is 0.1-0.17;

and (3) immersing the aluminum nitride ceramic wafer treated in the first step into a NaOH solution with the mass fraction of 20%, and performing ultrasonic treatment at 50 ℃ for 4 min.

Preferably, the surface roughness is measured by selecting the front and back surfaces of at least 5 test points on the aluminum nitride ceramic substrate, and taking the average value of the roughness of all the test points as a test result.

Further preferably, all test points include a central point located at the center, and the rest of the test points are located at the periphery of the central point and near the corners of the aluminum nitride ceramic substrate.

Has the advantages that: the surface coarsening degree of the ceramic chip is controlled by controlling the surface roughness of the ceramic chip, the method is simple and easy to implement, the combination of the ceramic chip and the solder layer can be obviously enhanced, and the technical problem of poor combination of the conventional AMB vacuum brazing aluminum nitride ceramic substrate and the solder layer is effectively solved.

Drawings

FIG. 1 is a flow chart of the present invention;

FIG. 2 is a graph showing the results of example 1 and comparative example 1 passing through an ultrasonic flaw detector;

wherein, A1 and B1 are result graphs obtained by an ultrasonic flaw detector by adopting the mode of comparative example 1 and randomly extracting 2 aluminum nitride ceramic substrates;

a2 and B2 are graphs showing results obtained by an ultrasonic flaw detector on 2 randomly selected aluminum nitride ceramic substrates in the manner described in example 1;

FIG. 3 is a schematic layout diagram of test points during roughness testing according to the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

Referring to fig. 1 to 3, embodiment 1 is a method for roughening a surface of an aluminum nitride ceramic substrate, including the following steps:

removing oil stains and impurities on the surface of an aluminum nitride ceramic substrate through an oil removing agent and pure water, and testing the surface roughness of the aluminum nitride ceramic substrate, wherein the initial surface roughness is 0.1-0.2;

immersing the aluminum nitride ceramic substrate treated in the step one in a NaOH solution with the mass fraction of 20%, and carrying out ultrasonic treatment for 4min at the temperature of 50 ℃;

thirdly, placing the aluminum nitride ceramic substrate treated in the second step on 1-3% of diluted H in mass fraction₂SO₄Treating in solution for 5-10 s at 15-25 deg.C℃；

Step four, pressurizing and washing the aluminum nitride ceramic substrate treated in the step three for 3min at normal temperature;

and step five, drying the aluminum nitride ceramic substrate processed in the step four, controlling the temperature to be 80-100 ℃ and the time to be 3-5 min.

And fifthly, testing the surface roughness of the aluminum nitride ceramic substrate, and controlling the surface roughness Ra of the aluminum nitride ceramic substrate to be 0.3-0.4.

Comparative example 1:

the aluminum nitride ceramic substrate is sequentially processed by the following steps:

firstly, removing oil stains and impurities on the surface of the aluminum nitride ceramic wafer through an oil removing agent and pure water, and testing initial surface roughness;

step two, pressurizing and washing the aluminum nitride ceramic wafer treated in the step (1) for 3min at normal temperature;

step three, drying the ceramic chip processed in the step (2), controlling the temperature to be 80-100 ℃ and the time to be 3 min;

and step four, testing the surface roughness of the aluminum nitride ceramic substrate.