Method for removing adhesion isolating powder on surface of silicon nitride ceramic substrate

Abstract

The invention discloses a method for removing adhesion isolating powder on the surface of a silicon nitride ceramic substrate in the technical field of ceramic material preparation. The method comprises the following steps: S1, atmosphere plasma activation modification: introducing argon and oxygen into a plasma generator, generating atmosphere plasma by adjusting the power of a power supply, placing a silicon nitride ceramic substrate on a conveyor belt, and passing through an atmosphere plasma modification area; s2, cleaning by an ultrasonic scrubbing machine: adjusting the ultrasonic frequency, setting the downward pressure of a carborundum brush head on the surface of the silicon nitride ceramic substrate, adjusting the pH value of a cleaning medium, placing the silicon nitride ceramic substrate on a conveyor belt, and processing the silicon nitride ceramic substrate through the carborundum brush head; s3, cleaning by spraying equipment: placing the silicon nitride ceramic substrate on a conveyor belt to pass through a water washing area; and S4, removing moisture by a fan. Compared with the prior art, the cleaning efficiency is higher, the particle residual rate is lower, subsequent damage to personnel and equipment is smaller, and damage and pollution to the surface of the substrate cannot be caused.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic material preparation, and in particular to a method for removing insulating and sticking powder on the surface of a silicon nitride ceramic substrate. Background Art

[0002] Silicon nitride (Si3N4) ceramics have high bending strength (≥700MPa) and high fracture toughness (8MPa·m 1 / 2 ), good thermal conductivity (≥80W·m -1 ·k -1 )) Good AC breakdown strength (40kV·mm -1 ) and other advantages, it is the basic material for SiC power modules in the fields of aerospace, new energy vehicles, rail transit, etc. As SiC power modules develop towards higher power density and faster charging speed, the thickness of Si3N4 ceramic substrates is required to develop in a thinner direction while ensuring the requirements of dimensional accuracy and shape accuracy. The processing flow of Si3N4 ceramic substrates is mainly divided into: mixing → casting → debinding → sintering → grinding → cleaning. Before the sintering process, the Si3N4 ceramic substrate needs to be sprinkled with isolation powder at the bottom of the sagger and between the ceramic sheets to prevent the mutual adhesion between the sintered ceramic sheets. During the sintering process, due to the thermal dynamic effect, the isolation powder will be embedded or bonded to the ceramic surface, resulting in a layer of isolation powder that is difficult to remove on the surface of the sintered silicon nitride ceramic substrate. After the sintering process of the silicon nitride ceramic substrate is completed and enters the grinding process, the isolation powder on the surface of the silicon nitride ceramic substrate needs to be removed first. At present, the common practice in the ceramic substrate industry is to first remove the isolation powder on the surface of the silicon nitride ceramic substrate by sandblasting, then wash with water to remove the corundum particles in the sandblasting process, and finally dry to remove the moisture on the surface of the silicon nitride ceramic substrate. However, the above technology has the following disadvantages: 1) The sandblasting process uses a booster pump as the power to form a high-speed jet beam to spray corundum at high speed onto the surface of the workpiece to be processed, so that the isolation powder on the surface of the workpiece is removed. However, the pressure distribution of the water jet cross section is uneven, and the matrix jet cannot completely cover the surface of the large-sized silicon nitride ceramic substrate, which makes it difficult to completely remove the isolation powder on the surface of the large-sized silicon nitride ceramic substrate during the sandblasting process; 2) The corundum used in the sandblasting process will also cause damage to the surface of the large-sized silicon nitride ceramic substrate during high-speed impact. In summary, the current industry common practice is difficult to effectively remove the isolation powder on the surface of the silicon nitride ceramic substrate, resulting in serious dust pollution in the subsequent laser cutting process, endangering the health of personnel and affecting the life and performance of the machine. Summary of the invention

[0003] In order to overcome the problem that the existing isolation and adhesion powder on the surface of silicon nitride ceramic substrate cannot be effectively removed, the present invention provides a method for removing the isolation and adhesion powder on the surface of silicon nitride ceramic substrate.

[0004] The technical solution adopted by the present invention to solve its technical problem is:

[0005] The method for removing the insulating powder on the surface of a silicon nitride ceramic substrate comprises the following steps: S1, atmospheric plasma activation modification: passing argon and oxygen into a plasma generator, generating atmospheric plasma by adjusting the power of the power supply, placing the silicon nitride ceramic substrate on a conveyor belt, and sequentially passing through an atmospheric plasma modification area; S2, ultrasonic scrubber cleaning: adjusting the ultrasonic frequency, setting the downward pressure of the diamond brush head on the surface of the silicon nitride ceramic substrate, adjusting the pH value of the cleaning medium, placing the silicon nitride ceramic substrate on a conveyor belt, and sequentially passing through a diamond brush head treatment area; S3, spray equipment cleaning: setting a water washing area, placing the silicon nitride ceramic substrate on a conveyor belt and sequentially passing through the water washing area; S4, fan dehumidification: using a fan to remove moisture on the silicon nitride ceramic substrate.

[0006] Compared with the prior art, the present application has higher cleaning efficiency and lower particle residue rate, less subsequent harm to personnel and equipment, and will not cause damage or contamination to the substrate surface.

[0007] Furthermore, in step S1, the distance from the plasma generator nozzle to the conveyor belt is 15nm-18nm, the argon and oxygen introduced into the plasma generator are 100slm-500slm and 1slm-10slm respectively, the power supply is 5kW-20kW, and the conveyor belt speed is adjusted to 2m / min-5m / min.

[0008] Furthermore, in step S2, the ultrasonic frequency is 20kHz-150kHz, the downward pressure of the diamond brush head on the surface of the large-sized silicon nitride ceramic substrate is 1.5psi-2.5psi, the cleaning medium is an aqueous solution with a pH of 9.5-10.5, and the conveyor belt speed is adjusted to 2m / min-5m / min.

[0009] Furthermore, the spray pressure of the spray machine water washing in step S3 is 1kgf / cm 2 -2kgf / cm 2 , the conveyor belt speed is adjusted to 2m / min-5m / min.

[0010] Furthermore, step S4 is to use a fan to remove moisture: first use a cold air blower to quickly remove most of the water droplets, and then use a hot air blower to dry the surface of the silicon nitride substrate.

[0011] Furthermore, in step S4, the air volume of the cooling fan is 1m 3 / min-10m 3 / min.

[0012] Furthermore, in step S4, the hot air blower is equipped with two upper and lower hot air knives, the temperature is 40℃-80℃, and the air volume is 1m 3 / min~10m 3 / min.

[0013] The beneficial effects of the present invention are: compared with the prior art, the method for removing isolation powder on the surface of a silicon nitride ceramic substrate provided by the present application has higher cleaning efficiency and lower particle residue rate, less subsequent harm to personnel and equipment, and will not cause damage or pollution to the substrate surface. DETAILED DESCRIPTION

[0014] 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 embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0015] The present invention provides a method for removing the isolation powder on the surface of a silicon nitride ceramic substrate. The process method is as follows: first, the isolation powder on the surface of the silicon nitride ceramic substrate is activated and modified by an atmospheric plasma jet, then the isolation powder on the surface of the silicon nitride ceramic substrate is cleaned by an ultrasonic scrubber, and then the residual impurities are cleaned by a spray device, and finally, a hot air blower is used to quickly dry and remove the moisture on the surface of the silicon nitride ceramic substrate. The method has higher cleaning efficiency, lower particle residue rate, less subsequent damage to personnel and equipment, and will not cause damage and pollution to the substrate surface.

[0016] The density of the large-size silicon nitride ceramic substrate used before cleaning is ≥3.2g / cm 3 , thickness is 0.1-1.0mm, warpage is <2mm, and there are no cracks, pits or defects in appearance.

[0017] The specific steps are as follows:

[0018] S1) atmospheric plasma activation modification: argon and oxygen are passed into a plasma generator, and a rectangular atmospheric plasma is generated by adjusting the power of the power supply, and large-sized silicon nitride ceramic substrates are regularly placed on a conveyor belt and sequentially passed through an atmospheric plasma modification area;

[0019] S2) Ultrasonic brush cleaning: Adjust the ultrasonic frequency, set the downward pressure of the diamond abrasive brush head on the surface of the large-sized silicon nitride ceramic substrate, adjust the pH value of the cleaning medium, and then place the large-sized silicon nitride ceramic substrates on the conveyor belt in a regular manner and pass through the diamond abrasive brush treatment area in sequence. Repeat this step 2-3 times.

[0020] S3) Spray equipment cleaning: Set up three water washing areas, and place large-sized silicon nitride ceramic substrates regularly on a conveyor belt and pass through the processing area in sequence. Repeat this step 2-3 times.

[0021] S4) Use a fan to remove moisture: First use a cold air blower to quickly remove most of the water droplets, and then use a hot air blower to dry the surface of the silicon nitride substrate.

[0022] Among them, the distance from the plasma generator nozzle to the conveyor belt in S1 is 15nm-18nm, the argon and oxygen introduced into the plasma generator are 100slm-500slm and 1slm-10slm respectively, the power supply is 5kW-20kW, and the conveyor belt speed is adjusted to 2m / min-5m / min;

[0023] Among them, the ultrasonic frequency in S2 is 20kHz-150kHz, the downward pressure of the diamond brush head on the surface of the large-sized silicon nitride ceramic substrate is 1.5psi-2.5psi, the cleaning medium is an aqueous solution with a pH of 9.5-10.5, and the conveyor belt speed is adjusted to 2m / min-5m / min;

[0024] The spray pressure of the water washing machine in S3 is 1kgf / cm 2 -2kgf / cm 2 , the cleaning medium is tap water, and the conveyor belt speed is adjusted to 2m / min-5m / min;

[0025] Among them, the air volume of S4 intercooler is 1m 3 / min-10m 3 / min, preferably 2m 3 / min-7m 3 / min;

[0026] Among them, in S4, the hot air blower is equipped with two upper and lower hot air knives, the temperature is 40℃-80℃, and the air volume is 1m 3 / min~10m 3 / min, preferably 2m 3 / min-7m 3 / min.

[0027] Embodiment 1

[0028] S1) Atmospheric plasma surface activation modification.

[0029] The modification conditions are as follows:

[0030] The distance from the plasma generator nozzle to the conveyor belt is 16 mm;

[0031] Power supply: 10kW;

[0032] Argon gas flow rate: 300slm;

[0033] Oxygen flow rate: 2slm;

[0034] The conveyor belt speed is 4m / min.

[0035] S2) Ultrasonic scrubber cleaning.

[0036] The cleaning conditions are as follows:

[0037] Ultrasonic frequency: 40kHz;

[0038] Brush head pressure: 2psi;

[0039] Cleaning medium pH: 10;

[0040] The conveyor belt speed is 4m / min.

[0041] S3) Use spray equipment for cleaning

[0042] The cleaning conditions are as follows:

[0043] Cleaning medium: tap water;

[0044] Spray pressure: 2kgf / cm 2 ;

[0045] The conveyor belt speed is 4m / min.

[0046] S4) Fan removes moisture

[0047] The drying conditions are as follows:

[0048] Cold and hot air volume: 5 cubic meters per minute;

[0049] Hot air temperature: 60℃;

[0050] The conveyor belt speed is 4m / min.

[0051] Embodiment 2

[0052] S1) Atmospheric plasma surface activation modification.

[0053] The modification conditions are as follows:

[0054] The distance from the plasma generator nozzle to the conveyor belt is 18mm; power supply: 18kW;

[0055] Argon flow rate: 400slm;

[0056] Oxygen flow rate: 5slm.

[0057] The conveyor belt speed is 3m / min.

[0058] S2) Ultrasonic scrubber cleaning.

[0059] The cleaning conditions are as follows:

[0060] Ultrasonic frequency: 60kHz;

[0061] Brush head pressure: 2psi;

[0062] Cleaning medium pH: 10;

[0063] The conveyor belt speed is 3m / min.

[0064] S3) Use spray equipment for cleaning

[0065] The cleaning conditions are as follows:

[0066] Cleaning medium: tap water;

[0067] Spray pressure: 2kgf / cm 2 ;

[0068] The conveyor belt speed is 3m / min.

[0069] S4) Fan removes moisture

[0070] The drying conditions are as follows:

[0071] Cold and hot air volume: 5 cubic meters per minute;

[0072] Hot air temperature: 60℃;

[0073] The conveyor belt speed is 3m / min.

[0074] Embodiment 3

[0075] S1) Atmospheric plasma surface activation modification.

[0076] The modification conditions are as follows:

[0077] The distance from the plasma generator nozzle to the conveyor belt is 15mm; power supply power: 6kW;

[0078] Argon gas flow rate: 150slm;

[0079] Oxygen flow rate: 8slm;

[0080] The conveyor belt speed is 2m / min.

[0081] S2) Ultrasonic scrubber cleaning.

[0082] The cleaning conditions are as follows:

[0083] Ultrasonic frequency: 120kHz;

[0084] Brush head pressure: 2psi;

[0085] Cleaning medium pH: 10;

[0086] The conveyor belt speed is 2m / min.

[0087] S3) Use spray equipment for cleaning

[0088] The cleaning conditions are as follows:

[0089] Cleaning medium: tap water;

[0090] Spray pressure: 2kgf / cm 2 ;

[0091] The conveyor belt speed is 2m / min.

[0092] S4) Fan removes moisture

[0093] The drying conditions are as follows:

[0094] Cold air volume and hot air volume: 5 cubic meters per minute;

[0095] Hot air temperature: 60℃;

[0096] The conveyor belt speed is 2m / min.

[0097] Comparative Example 1

[0098] S1) Cleaning with sandblasting machine.

[0099] The sandblasting conditions are as follows:

[0100] Sandblasting pressure: 3kgf / cm 2 ;

[0101] Sandblasting fluid concentration: 20wt%;

[0102] Diamond grain size for sandblasting: 100 mesh;

[0103] The conveyor belt speed is 1.8m / min.

[0104] S2) Use a spray machine to clean.

[0105] The cleaning conditions are as follows:

[0106] Cleaning medium: tap water;

[0107] Spray pressure: 2kgf / cm 2 ;

[0108] The conveyor belt speed is 1.8m / min.

[0109] S3) Drying with a hot air blower.

[0110] The drying conditions are as follows:

[0111] Air volume: 5 cubic meters per minute;

[0112] Temperature: 60℃;

[0113] The conveyor belt speed is 1.8m / min.

[0114] The cleaning performance comparison between the above embodiment and the comparative example is shown in the following table:

[0115] Table 1 Comparison of cleaning performance

[0116] Residual rate of isolating powder Cleaning efficiency (pieces / hour) Surface state Example 1 0.5％ 750 No water stains, no damage Example 2 0.7％ 750 No water stains, no damage Example 3 0.6％ 750 No water stains, no damage Comparative Example 1 7.1％ 600 Minor water stains, minor damage

[0117] In summary, we can conclude that:

[0118] 1) The present invention can significantly reduce the residual rate of isolating powder on the surface of silicon nitride ceramic substrate from about 7% to about 0.6%;

[0119] 2) The cleaning efficiency of the method provided by the present invention is higher. The cleaning efficiency of the prior art is 600 pieces / hour, while the cleaning efficiency of the present invention is 750 pieces / hour, which is 25% higher;

[0120] 3) The present invention will not cause additional damage or pollution to the surface of the silicon nitride ceramic substrate.

[0121] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for removing sticky powder from the surface of a silicon nitride ceramic substrate, characterized in that: The following steps are involved: S1. Atmospheric plasma activation modification: Argon and oxygen are passed into the plasma generator, and atmospheric plasma is generated by adjusting the power supply. The silicon nitride ceramic substrate is placed on a conveyor belt and sequentially passes through the atmospheric plasma modification area; S2, ultrasonic scrubber cleaning: adjusting the ultrasonic frequency, setting the downward pressure of the diamond abrasive brush head on the surface of the silicon nitride ceramic substrate, adjusting the pH value of the cleaning medium, placing the silicon nitride ceramic substrate on the conveyor belt, and sequentially passing through the diamond abrasive brush head treatment area; S3, spray equipment cleaning: set up a water washing area, place the silicon nitride ceramic substrate on a conveyor belt and pass through the water washing area in sequence; S4. Use a fan to remove moisture: Use a fan to remove moisture from the silicon nitride ceramic substrate.

2. The method for removing the anti-sticking powder on the surface of the silicon nitride ceramic substrate according to claim 1, characterized in that: In step S1, the distance from the plasma generator nozzle to the conveyor belt is 15nm-18nm, the argon and oxygen introduced into the plasma generator are 100slm-500slm and 1slm-10slm respectively, the power supply is 5kW-20kW, and the conveyor belt speed is adjusted to 2m / min-5m / min.

3. The method for removing the anti-sticking powder on the surface of the silicon nitride ceramic substrate according to claim 1, characterized in that: In step S2, the ultrasonic frequency is 20kHz-150kHz, the downward pressure of the diamond brush head on the surface of the large-sized silicon nitride ceramic substrate is 1.5psi-2.5psi, the cleaning medium is an aqueous solution with a pH of 9.5-10.5, and the conveyor belt speed is adjusted to 2m / min-5m / min.

4. The method for removing the anti-sticking powder on the surface of the silicon nitride ceramic substrate according to claim 1, characterized in that: The spray pressure of the spray machine water washing in step S3 is 1kgf / cm 2 -2kgf / cm 2 , the conveyor belt speed is adjusted to 2m / min-5m / min.

5. The method for removing the anti-sticking powder on the surface of the silicon nitride ceramic substrate according to any one of claims 1 to 4, characterized in that: Step S4 is to use a fan to remove moisture: first use a cold air blower to quickly remove most of the water droplets, and then use a hot air blower to dry the surface of the silicon nitride substrate.

6. The method for removing the anti-sticking powder on the surface of the silicon nitride ceramic substrate according to claim 5, characterized in that: In step S4, the air volume of the cooling fan is 1m 3 / min-10m 3 / min.

7. The method for removing the anti-sticking powder on the surface of the silicon nitride ceramic substrate according to claim 5, characterized in that: In step S4, the hot air blower is equipped with two upper and lower hot air knives, the temperature is 40℃-80℃, and the air volume is 1m 3 / min~10m 3 / min.