A method for manufacturing a super-large-size silicon carbide vapor chamber

Abstract

The application discloses a large-size silicon carbide heat-distribution plate manufacturing method, and belongs to the technical field of special ceramic products, and comprises the following steps: step 1, large-size mold core design; step 2, mold manufacturing; step 3, blank casting; step 4, blank repairing and processing; step 5, vacuum reaction sintering; and step 6, sand cleaning and quality inspection. The large-size silicon carbide heat-distribution plate is subjected to sand cleaning to remove residual silicon on the surface, and after size and strength detection of the product after sand cleaning, a finished product is obtained. According to the product shrinkage rate and the shrinkage direction, the mold is designed, the two end faces are made to be inclined to facilitate end shrinkage, the blank drying direction is the taper direction between the two end faces, the taper design leaves space for the blank shrinkage deformation, facilitates the shrinkage release in the blank casting and drying process, and therefore the forming qualification rate of the blank is ensured.

Description

Technical Field

[0001] This invention relates to the field of special ceramic products technology, specifically to a method for manufacturing an ultra-large silicon carbide heat spreader. Background Technology

[0002] Glass substrates are at the very upstream of the LCD panel industry chain and represent the link with the highest technological barriers in the entire industry chain.

[0003] Silicon carbide vapor chambers are used in the forming furnace of glass substrates produced by overflow melting method. They are one of the key core equipment in the glass substrate melting and forming stage. The good thermal conductivity and high temperature performance of the product play a key role in improving the quality of glass substrates. The production of existing mature silicon carbide vapor chambers mostly adopts the isostatic pressing process to obtain blanks. However, in order to ensure the uniformity of powder flow, the isostatic pressing process cannot realize the manufacturing of ultra-large silicon carbide vapor chambers. Therefore, ultra-large silicon carbide vapor chambers mostly adopt the casting process. However, due to the large cross-sectional size and long length of ultra-large silicon carbide vapor chambers, the casting process is prone to deformation and shrinkage fracture during blank casting. At the same time, the sintering process is prone to bending deformation, shrinkage cracks or even fractures due to the large size of the blanks, resulting in an extremely low forming rate of ultra-large silicon carbide vapor chambers. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention provides a method for manufacturing ultra-large silicon carbide heat spreaders, which can meet the various technical and parameter requirements of large-size heat spreaders and effectively improve the forming rate of ultra-large silicon carbide heat spreaders.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for manufacturing an ultra-large silicon carbide heat spreader, wherein the ultra-large silicon carbide heat spreader has a length of 3000-4100 mm, a width of 130-180 mm, and a thickness of 110-140 mm, and the manufacturing method includes the following steps: Step 1, Oversized mold core design: Design the mold core drawing, process the mold core according to the drawing, the two opposite end faces of the mold core adopt the design of inclined surfaces with opposite directions, and reserve the specified length allowance; Step 2, Mold making: The mold core is covered with plaster to make the master mold, and then the plaster mold is made using the master mold; Step 3, Casting the blank: The mixed silicon carbide slurry is pressed into the plaster mold under pressure, and the blank is cured according to the calculated slurry absorption time of the mold. During the curing process, the slurry needs to be replenished. Step 4, Blank Repair and Processing: After the formed blank is demolded from the plaster mold, it is dried once and then dried twice. Then it is placed on the processing fixture for blank processing and repair. Step 5, Vacuum reaction sintering: Load the processed and inspected blanks into the furnace, place them on a special graphite sintering fixture, lay a protective pad on the special sintering fixture, and then put them into the furnace and perform vacuum sintering according to the pre-set electric furnace operation program. Step 6, Sand Removal and Quality Inspection: The extra-large silicon carbide heat spreader is sand removed to remove residual silicon from the surface. The finished product is then tested for size and strength.

[0006] Preferably, in step 1, there is an included angle between the two end faces of the mold core, and the included angle is set to 56 degrees.

[0007] Preferably, in step 4, after the formed blank is demolded from the plaster mold, it is sent to the drying room for the first drying at a temperature of 35-50 degrees Celsius for 30-40 hours, and then a second drying is performed at a temperature of 80-100 degrees Celsius for 24-30 hours. After that, the blank is processed and repaired.

[0008] Preferably, the heating and sintering process in step 5 includes a heating stage, a constant temperature stage, and a power-off cooling stage. The heating time is 20-25 hours, reaching 1700℃. After maintaining the temperature at 1700℃ for 2-4 hours, the power is turned off and a vacuum is drawn to cool down the furnace to 1350℃. Then, high-purity nitrogen is introduced into the furnace as a protective gas. After cooling down to the specified furnace exit temperature using circulating water, the furnace exits to obtain the ultra-large silicon carbide uniform temperature plate.

[0009] Preferably, during the blank casting stage, the silicon carbide slurry is obtained by uniformly mixing 5-8 parts by weight of silicon carbide micro powder, 0.05-0.12 parts by weight of carbon black, 0.1-0.3 parts by weight of binder, and 3-4 parts by weight of distilled water.

[0010] Preferably, the protective pad layer in step 5 is a carbon fiber layer, and the thickness of the carbon fiber layer is 10 mm.

[0011] Preferably, the special graphite sintering fixture includes a plurality of mounting seats that are linearly and uniformly distributed. The mounting seats are provided with mounting grooves for placing silicon carbide heat spreaders, and the carbon fiber layer is installed in the mounting grooves.

[0012] The beneficial effects of this invention are as follows: 1. In the present invention, when making the mold, the mold is designed according to the shrinkage rate and shrinkage direction of the product. The two ends are made into an oblique shape to facilitate the shrinkage of the ends. When the blank is dried, the shrinkage direction is along the tapered direction between the two ends. The tapered design leaves space for the shrinkage deformation of the blank, which facilitates the release of shrinkage during the blank casting and drying process, thus ensuring the forming qualification rate of the blank. 2. In this invention, a special graphite sintering fixture is made during the blank sintering process. High-temperature carbon fiber is laid on the fixture, and the sintered product is placed on top. The carbon fiber layer has good elasticity. When the silicon carbide heat spreader deforms during sintering, the carbon fiber layer can achieve relative movement between the silicon carbide heat spreader and the mounting groove while ensuring support. This can effectively avoid stress concentration in the silicon carbide heat spreader and effectively release the problem of high-temperature shrinkage and deformation of the silicon carbide heat spreader during sintering. Attached Figure Description

[0013] Figure 1 This is a schematic diagram showing the placement of the silicon carbide heat spreader in a vacuum sintering furnace in a method for manufacturing an ultra-large silicon carbide heat spreader according to the present invention. Figure 2 This is a partial structural diagram of the mold used in the method for manufacturing an ultra-large silicon carbide heat spreader according to the present invention.

[0014] In the diagram: 1-Extra-large temperature distribution plate, 2-Graphite sintering fixture, 3-High-temperature carbon fiber. Detailed Implementation

[0015] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0016] Example 1: A method for manufacturing an ultra-large silicon carbide heat spreader includes the following steps: Step 1, Oversized mold core design: The mold core is processed according to the dimensions of 3670mm in length, 130mm in width, and 116mm in thickness. The two opposite end faces of the mold core in the length direction are designed with inclined surfaces in opposite directions, and the included angle between the two inclined surfaces is set to 56°. The minimum distance between the two end faces of the mold core in the length direction is greater than 3500mm. Step 2, Mold Making: A master mold is created by covering the mold core with plaster slurry. Then, a plaster mold is made using the master mold. After molding, the internal forming space of the plaster mold has a conical structure. The mold is designed according to the product's shrinkage rate and shrinkage direction. Figure 2 The two ends are made at an angle to facilitate end shrinkage. When the blank dries, it shrinks along the tapered direction between the two ends. The tapered design leaves space for the shrinkage and deformation of the blank, which facilitates the release of shrinkage during the blank casting and drying process, thus ensuring the blank's forming qualification rate. Step 3, Casting blank: Mix 5-7 parts by weight of silicon carbide micro powder, 0.05-0.08 parts of carbon black, 0.1-0.2 parts of binder, and 3-4 parts of distilled water to obtain silicon carbide slurry. Press the mixed silicon carbide slurry into the plaster mold under pressure. Cure the blank according to the calculated mold slurry absorption time. During the curing process, slurry needs to be replenished. Step 4, Blank Repair and Processing: Demold the formed blank from the plaster mold and send it into the drying room for the first drying at a temperature of 35-50 degrees Celsius for 30-35 hours. Then, perform a second drying at a temperature of 80-100 degrees Celsius for 24-26 hours. After that, process and repair the blank. Step 5, vacuum reaction sintering: as follows Figure 1 The high-temperature drying chamber shown has several linearly and uniformly distributed mounting slots for placing the blanks. After the product is placed in the mounting slot with a 10mm carbon fiber layer, it is sintered. The carbon fiber layer has good elasticity. When the silicon carbide heat spreader deforms during sintering, the carbon fiber layer can provide support while allowing relative movement between the silicon carbide heat spreader and the mounting slot. This can effectively avoid stress concentration in the silicon carbide heat spreader and effectively release the problem of high-temperature shrinkage deformation of the silicon carbide heat spreader during sintering. After the electric furnace is powered on, the heating time is 22 hours, reaching 1700℃. After maintaining the temperature at 1700℃ for 2 hours, the power is turned off and a vacuum is drawn to cool down. When the temperature drops to 1350℃, the vacuum is stopped and the furnace is filled with high-purity nitrogen as a protective gas. After cooling down to below 200℃ using circulating water, the ultra-large silicon carbide heat spreader is obtained. Step 6, Sand Removal and Quality Inspection: The extra-large silicon carbide heat spreader is sand removed to remove excess residual silicon from the surface. The finished product is then tested for size and strength after sand removal.

[0017] Tests showed that the yield of the sintered product was greater than 99.3%.

[0018] Example 2: A method for manufacturing an ultra-large silicon carbide heat spreader includes the following steps: Step 1, Oversized mold core design: The mold core is processed according to the dimensions of 3900mm in length, 140mm in width, and 128mm in thickness. The two opposite end faces of the mold core in the length direction adopt an inclined surface design with opposite directions. The minimum distance between the two end faces of the mold core in the length direction is greater than 3700mm. Step 2, Mold Making: A master mold is created by covering the mold core with plaster slurry. Then, a plaster mold is made using the master mold. After molding, the internal forming space of the plaster mold has a conical structure. The mold is designed according to the product's shrinkage rate and shrinkage direction. Figure 2 The two ends are made at an angle to facilitate end shrinkage. When the blank dries, it shrinks along the tapered direction between the two ends. The tapered design leaves space for the shrinkage and deformation of the blank, which facilitates the release of shrinkage during the blank casting and drying process, thus ensuring the blank's forming qualification rate. Step 3, Casting the blank: Mix 6-7 parts by weight of silicon carbide micro powder, 0.05-0.1 parts of carbon black, 0.15-0.25 parts of binder, and 3-4 parts of distilled water to obtain a silicon carbide slurry. Press the mixed silicon carbide slurry into the plaster mold under pressure. Cure the blank according to the calculated mold slurry absorption time. During the curing process, slurry needs to be replenished. Step 4, Blank Repair and Processing: Demold the formed blank from the plaster mold and send it into the drying room for the first drying at a temperature of 35-50 degrees Celsius for 33-37 hours. Then, perform a second drying at a temperature of 80-100 degrees Celsius for 25-28 hours. After that, process and repair the blank. Step 5, vacuum reaction sintering: as follows Figure 1 The high-temperature drying chamber shown has several linearly and uniformly distributed mounting slots for placing the blanks. After the product is placed in the mounting slot with a 10mm carbon fiber layer, it is sintered. The carbon fiber layer has good elasticity. When the silicon carbide heat spreader deforms during sintering, the carbon fiber layer can provide support while allowing relative movement between the silicon carbide heat spreader and the mounting slot. This can effectively avoid stress concentration in the silicon carbide heat spreader and effectively release the problem of high-temperature shrinkage and deformation of the silicon carbide heat spreader during sintering. After the electric furnace is powered on, the heating time is 22 hours, reaching 1700℃. After maintaining the temperature at 1700℃ for 2 hours, the power is turned off and a vacuum is drawn to cool down. When the temperature drops to 1350℃, the vacuum is stopped and the furnace is filled with high-purity nitrogen as a protective gas. After cooling down to below 200℃ using circulating water, the ultra-large silicon carbide heat spreader is obtained. Step 6, Sand Removal and Quality Inspection: The extra-large silicon carbide heat spreader is sand removed to remove excess residual silicon from the surface. The finished product is then tested for size and strength after sand removal.

[0019] Tests showed that the yield of the sintered product was greater than 99.5%.

[0020] Example 3: A method for manufacturing an ultra-large silicon carbide heat spreader includes the following steps: Step 1, Oversized mold core design: The mold core is processed according to the dimensions of 4100mm in length, 150mm in width, and 136mm in thickness. The two opposite end faces of the mold core in the length direction adopt an inclined surface design with opposite directions. The minimum distance between the two end faces of the mold core in the length direction is greater than 3900mm. Step 2, Mold Making: A master mold is created by covering the mold core with plaster slurry. Then, a plaster mold is made using the master mold. After molding, the internal forming space of the plaster mold has a conical structure. The mold is designed according to the product's shrinkage rate and shrinkage direction. Figure 2The two ends are made at an angle to facilitate end shrinkage. When the blank dries, it shrinks along the tapered direction between the two ends. The tapered design leaves space for the shrinkage and deformation of the blank, which facilitates the release of shrinkage during the blank casting and drying process, thus ensuring the blank's forming qualification rate. Step 3, casting blank: Mix 6-8 parts by weight of silicon carbide micro powder, 0.05-0.11 parts of carbon black, 0.2-0.3 parts of binder, and 3-4 parts of distilled water to obtain silicon carbide slurry. Pour the mixed silicon carbide slurry into the plaster mold and let it stand for a period of time until the silicon carbide slurry solidifies to complete the shaping. Step 4, Blank Repair and Processing: Demold the formed blank from the plaster mold and send it into the drying room for the first drying at a temperature of 35-50 degrees Celsius for 36-40 hours. Then, perform a second drying at a temperature of 80-100 degrees Celsius for 28-30 hours. After that, process and repair the blank. Step 5, vacuum reaction sintering: as follows Figure 1 The high-temperature drying chamber shown has several linearly and uniformly distributed mounting slots for placing the blanks. After the product is placed in the mounting slot with a 10mm carbon fiber layer, it is sintered. The carbon fiber layer has good elasticity. When the silicon carbide heat spreader deforms during sintering, the carbon fiber layer can provide support while allowing relative movement between the silicon carbide heat spreader and the mounting slot. This can effectively avoid stress concentration in the silicon carbide heat spreader and effectively release the problem of high-temperature shrinkage deformation of the silicon carbide heat spreader during sintering. After the electric furnace is powered on, the heating time is 22 hours, reaching 1700℃. After maintaining the temperature at 1700℃ for 2 hours, the power is turned off and a vacuum is drawn to cool down. When the temperature drops to 1350℃, the vacuum is stopped and the furnace is filled with high-purity nitrogen as a protective gas. After cooling down to below 200℃ using circulating water, the ultra-large silicon carbide heat spreader is obtained. Step 6, Sand Removal and Quality Inspection: The extra-large silicon carbide heat spreader is sand removed to remove excess residual silicon from the surface. The finished product is then tested for size and strength after sand removal.

[0021] Tests showed that the yield of the sintered product was greater than 99%.

[0022] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A method for manufacturing an ultra-large silicon carbide heat spreader, characterized in that, The ultra-large silicon carbide heat spreader is set to a length of 3000-4100mm, a width of 130-180mm, and a thickness of 110-140mm. The manufacturing method includes the following steps: Step 1, Oversized mold core design: Design the mold core drawing, process the mold core according to the drawing, and design the two opposite end faces of the mold core in the length direction with inclined surfaces in opposite directions, and reserve the specified length allowance; Step 2, Mold making: The mold core is covered with plaster to make a master mold, and then the plaster mold is made using the master mold. After molding, the internal molding space of the plaster mold is a conical structure. Step 3, Casting the blank: The mixed silicon carbide slurry is pressed into the plaster mold under pressure, and the blank is cured according to the calculated slurry absorption time of the mold. During the curing process, the slurry needs to be replenished. Step 4, Blank Repair and Processing: After the formed blank is demolded from the plaster mold, it is dried once and then dried twice. The temperature of the second drying is higher than that of the first drying. Then it is placed on the processing fixture for blank processing and repair. Step 5, Vacuum reaction sintering: Load the processed and inspected blanks into the furnace, lay a protective pad on the special sintering fixture, place the blanks on the protective pad, and then put them into the furnace and perform vacuum sintering according to the pre-set electric furnace operation program. Step 6, Sand Removal and Quality Inspection: The extra-large silicon carbide heat spreader is sand removed to remove residual silicon from the surface. The finished product is then tested for size and strength.

2. The method for manufacturing an ultra-large silicon carbide heat spreader according to claim 1, characterized in that, In step 1, the two end faces of the mold core along its length are set as an included angle, which is set to 56 degrees.

3. The method for manufacturing an ultra-large silicon carbide heat spreader according to claim 1, characterized in that, The heating sintering process in the vacuum reaction sintering step includes a heating stage, a constant temperature stage, and a power-off cooling stage. The heating time is 20-25 hours, reaching 1700℃. After maintaining the temperature at 1700℃ for 2-4 hours, the power is turned off and a vacuum is drawn for cooling. When the temperature drops to 1350℃, the vacuuming is stopped, and then high-purity nitrogen is introduced into the furnace as a protective gas. After naturally cooling to room temperature, the furnace is removed to obtain the ultra-large silicon carbide uniform temperature plate.

4. The method for manufacturing an ultra-large silicon carbide heat spreader according to claim 1, characterized in that, The silicon carbide slurry in the blank casting step is obtained by uniformly mixing 5-8 parts by weight of silicon carbide micro powder, 0.05-0.12 parts by weight of carbon black, 0.1-0.3 parts by weight of binder, and 3-4 parts by weight of distilled water.

5. The method for manufacturing an ultra-large silicon carbide heat spreader according to claim 1, characterized in that, The protective pad layer in the vacuum reaction sintering step is a carbon fiber layer with a thickness of 10 mm.

6. The method for manufacturing an ultra-large silicon carbide heat spreader according to claim 5, characterized in that, The special graphite sintering fixture in the vacuum reaction sintering step includes several mounting seats that are linearly and uniformly distributed. The mounting seats are provided with mounting grooves for placing silicon carbide heat spreaders, and the carbon fiber layer is installed in the mounting grooves.

7. The method for manufacturing an ultra-large silicon carbide heat spreader according to claim 1, characterized in that, During the blank repair and processing stage, the formed blank is demolded from the plaster mold and sent to the drying room for the first drying at a temperature of 35-50 degrees Celsius for 30-40 hours. Then, it is dried a second time at a temperature of 80-100 degrees Celsius for 24-30 hours before the blank is processed and repaired.

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