A method for producing a porous alumina ceramic suction cup

Abstract

The application discloses a preparation method of a porous alumina ceramic suction disc, and comprises the following steps: putting graphite powder into an ethanol aqueous solution and performing ultrasonic treatment, filtering and drying to obtain clean graphite powder; adding aluminum isopropyl alcohol into ethanol and stirring uniformly, then adding the graphite powder and performing low-temperature microwave reaction, filtering and drying to obtain coated graphite powder; adding acrylamide into a mixture of diethyl ether and ethanol and stirring uniformly, then adding aluminum isopropyl alcohol, gradually adding distilled water and stirring until no distilled water is generated, to obtain a preliminary slurry; concentrating the preliminary slurry, diluting with water, then adding an initiator and a catalyst, adding the coated graphite powder and performing constant-temperature reaction to form a pre-prepared gel; putting the gel into a mold, slowly heating and performing heat preservation treatment, performing sintering treatment after cooling and demolding, to obtain the porous alumina ceramic suction disc. The application forms a homogeneous liquid film structure on the surface of the graphite powder by using the solubility and coating property of the aluminum isopropyl alcohol, and the strength of the alumina ceramic suction disc is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramics, and particularly relates to a preparation method of a porous alumina ceramic suction disc. BACKGROUND

[0002] Semiconductor devices have very strict requirements for wafers, only wafers close to perfect can avoid electrical and mechanical defects which are very harmful to devices, so multiple steps such as wafer shaping, slicing, grinding, cleaning and the like are needed. In these processes, a worktable that can place and fix a chip is needed, and a ceramic suction disc is used, that is, a large number of uniform solids or vacuum bodies are connected or enclosed in the material by high-temperature sintering, and the semiconductor chip, glass substrate material and the like work objects are fixed by vacuum suction. The sol-gel method is to use compounds containing high-chemical-activity components as precursors, uniformly mix these raw materials in a liquid phase, and carry out hydrolysis and condensation chemical reactions to form a stable transparent sol system in the solution. The sol slowly polymerizes between the gel particles after aging, forming a three-dimensional network structure of the gel, and the gel network is filled with a solvent that has lost fluidity, forming a gel. With the increasing demand for porous ceramic materials, inorganic pore-forming agents are widely used in semiconductor suction disc processes due to their stable structure and the like. However, the inorganic pore-forming agent generally adopts a surface inert material, and the surface has a certain reaction inertness, which produces marginal cracks in the gel injection molding, causing the strength of the suction disc to decrease. SUMMARY

[0003] In view of the problems in the prior art, the application provides a preparation method of a porous alumina ceramic suction disc, which solves the problem of local gaps caused by the inertness of graphite powder, uses the solubility and coating property of aluminum isopropyl alcohol to form a homogeneous liquid film structure on the surface of the graphite powder, and converts the liquid film into aluminum hydroxide, so that the gaps are repaired, and the strength of the alumina ceramic suction disc is improved.

[0004] To achieve the above technical purposes, the technical scheme of the application is as follows:

[0005] A preparation method of a porous alumina ceramic suction disc, comprising the following steps:

[0006] Step 1, graphite powder is put into an ethanol aqueous solution for ultrasonic treatment for 20-40 min, and then filtered and dried to obtain clean graphite powder, the volume ratio of ethanol in the ethanol aqueous solution is 50-60%, the concentration of the graphite powder in the ethanol aqueous solution is 100-400 g / L, the ultrasonic frequency of the ultrasonic treatment is 50-80 kHz, the temperature is 20-40 DEG C, and the drying temperature is 120-140 DEG C; this step uses the ultrasonic mode to clean the surface of the graphite powder, removes the impurities on the surface of the graphite powder, and increases the exposed surface of the graphite powder; the particle size of the graphite powder is 1-300 mu m;

[0007] Step 2, stirring the isopropyl alcohol aluminum in ethanol to form aluminum alcohol solution, then adding graphite powder and low-temperature microwave reaction for 1-2h, after filtering and drying to obtain coated graphite powder, the concentration of isopropyl alcohol aluminum in ethanol is 50-100g / L, the stirring speed is 300-500r / min, the concentration of graphite powder in aluminum alcohol solution is 100-150g / L, the temperature of low-temperature microwave reaction is 20-30℃, the microwave power is 100-300W; the drying temperature is 90-100℃, and the drying is carried out in a nitrogen atmosphere; this step utilizes the solubility and homogeneous dispersibility of isopropyl alcohol aluminum in ethanol, when the graphite powder is put into the aluminum alcohol solution, a liquid film of aluminum alcohol solution is formed on the surface of the graphite powder, the action of low temperature and microwave ensures that the liquid film completely adheres to the surface of the graphite powder, reducing the existence of bubbles;

[0008] Step 3, stirring acrylamide into an ether-ethanol mixture, then adding isopropyl alcohol aluminum and forming a mixture, then gradually adding distilled water and stirring until no more distilled water is produced to obtain a preliminary slurry; the volume ratio of ether to ethanol in the ether-ethanol mixture is 3-5:2, the stirring speed is 300-500r / min, the amount of isopropyl alcohol aluminum added is 400-600% of the mass of acrylamide, and the dropwise addition rate of distilled water is 3-5mL / min; this step utilizes the solubility of ether for acrylamide and the solubility of ethanol for isopropyl alcohol aluminum, thereby forming a mixed system, when distilled water is slowly added, isopropyl alcohol aluminum absorbs rapidly dispersed water molecules to form a hydrolysis reaction, resulting in a flocculent white precipitate, which is quickly dispersed throughout the slurry with the flow rate changes brought about by stirring;

[0009] Step 4, after concentrating the preliminary slurry, water is added to dilute it to form a pre-prepared slurry, then an initiator and a catalyst are added, coated graphite powder is added and a constant temperature reaction is carried out to form a pre-prepared gel; the concentration temperature is 20-30℃, the stirring speed is 200-400r / min, the concentration of acrylamide in the pre-prepared slurry is 20-40g / L, the initiator is ammonium persulfate, and the amount of initiator added is 5-10% of the mass of acrylamide, the catalyst is tetramethyl ethylenediamine, and the amount of catalyst added is 2-5% of the mass of acrylamide, the constant temperature reaction temperature is 60-80℃; this step utilizes the dilution method to diffuse a large amount of water, and after the addition of the initiator, catalyst and coated graphite powder, the isopropyl alcohol aluminum on the coated graphite powder is converted in situ to aluminum hydroxide, which is adsorbed on the surface of the graphite powder, and the catalyst and initiator form a stable acrylamide polymerization during the constant temperature reaction, forming a polyacrylamide gel structure;

[0010] Step 5, the gel is placed into a mold and slowly heated and kept warm, and after cooling and demolding, a blank is obtained, and the blank is sintered to obtain a porous alumina ceramic suction disc; the slow heating temperature is 4-10℃ / min, and the temperature for keeping warm is 200-300℃; the sintering treatment is carried out in an oxygen-rich atmosphere, and the oxygen content is 30-35%, and the sintering temperature is 1250-1550℃. This step utilizes the structural characteristics of aluminum hydroxide itself, converts into an alumina structure during keeping warm, and utilizes the adsorption of the alumina structure to form a local oxygen enrichment in an oxygen-rich environment, thereby realizing the formation of a porous alumina structure.

[0011] As can be seen from the above description, the present application has the following advantages:

[0012] 1. The present application solves the problem of local gaps caused by the inertness of graphite powder, utilizes the solubility and coating property of aluminum isopropyl alcohol itself to form a homogeneous liquid film structure on the surface of graphite powder, and converts the liquid film into aluminum hydroxide, thereby achieving gap repair and improving the strength of the alumina ceramic suction disc.

[0013] 2. The present application realizes the miniaturization of aluminum hydroxide by using liquid deposition combined with aluminum isopropyl alcohol hydrolysis, improves the homogeneous dispersion of aluminum hydroxide in polyacrylamide, and thereby improves the homogeneous dispersion on the alumina ceramic suction disc.

[0014] 3. The present application utilizes the polycondensation reaction of aluminum hydroxide in the gel and aluminum hydroxide on the surface of the plated graphite during keeping warm, effectively ensures the integration of the aluminum hydroxide material, ensures local polycondensation shrinkage, and reduces the formation of gaps. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a ceramic suction disc of Example 1: the gap size is 4 microns, and the porosity is 42%;

[0016] Figure 2 is a microstructure of the porous alumina ceramic in the ceramic suction disc of Example 1: the gap size is 4 microns, and the porosity is 42%. DETAILED DESCRIPTION

[0017] In combination Figure 1 and Figure 2 , a specific embodiment of the present application is described in detail, but does not limit the claims of the present application.

[0018] Example 1

[0019] A preparation method of a porous alumina ceramic suction disc, comprising the following steps:

[0020] Step 1, put the graphite powder into the ethanol aqueous solution and ultrasonic treatment for 20 min, filter and dry to obtain clean graphite powder, the volume ratio of ethanol in the ethanol aqueous solution is 50%, the concentration of graphite powder in the ethanol aqueous solution is 100 g / L, the ultrasonic frequency is 50 kHz, the temperature is 20℃, and the drying temperature is 120℃; the particle size of the graphite powder is 6 μm;

[0021] Step 2, add aluminum isopropyl alcohol into ethanol and stir to form aluminum alcohol solution, then add graphite powder and low-temperature microwave reaction for 1 h, filter and dry to obtain coated graphite powder, the concentration of aluminum isopropyl alcohol in ethanol is 50 g / L, the stirring speed is 300 r / min, the concentration of graphite powder in aluminum alcohol solution is 100 g / L, the temperature of low-temperature microwave reaction is 20℃, and the microwave power is 100 W; the drying temperature is 90℃, and the drying is carried out in a nitrogen atmosphere;

[0022] Step 3, add acrylamide into the ether-ethanol mixture and stir, then add aluminum isopropyl alcohol and form a mixture, then gradually add distilled water and stir until no more distilled water is produced to obtain a preliminary slurry; the volume ratio of ether to ethanol in the ether-ethanol mixture is 3:2, the stirring speed is 300 r / min, the amount of aluminum isopropyl alcohol added is 400% of the mass of acrylamide, and the dropping speed of distilled water is 3 mL / min;

[0023] Step 4, concentrate the preliminary slurry, then dilute with water to form a pre-prepared slurry, then add an initiator and a catalyst, add coated graphite powder and constant temperature reaction to form a pre-prepared gel; the concentration temperature is 20℃, the stirring speed is 200 r / min, the concentration of acrylamide in the pre-prepared slurry is 20 g / L, the initiator is ammonium persulfate, and the amount of initiator added is 5% of the mass of acrylamide, the catalyst is tetramethyl ethylenediamine, and the amount of catalyst added is 2% of the mass of acrylamide, and the constant temperature reaction temperature is 60℃;

[0024] Step 5, put the above gel into a mold, slowly heat and keep warm, cool and demold to obtain a green body, then sinter the green body to obtain a porous alumina ceramic suction disc; the slow heating temperature is 4℃ / min, and the holding temperature is 200℃; the sintering atmosphere is an oxygen-rich atmosphere, and the oxygen content is 30%, and the sintering temperature is 1250℃.

[0025] Example 2

[0026] A method for preparing a porous alumina ceramic suction disc, comprising the following steps:

[0027] Step 1, put the graphite powder into the ethanol aqueous solution and ultrasonic treatment for 40 min, filter and dry to obtain clean graphite powder, the volume ratio of ethanol in the ethanol aqueous solution is 60%, the concentration of graphite powder in the ethanol aqueous solution is 400 g / L, the ultrasonic frequency is 80 kHz, the temperature is 40℃, and the drying temperature is 140℃; the particle size of the graphite powder is 300 μm;

[0028] Step 2, add aluminum isopropyl alcohol into ethanol and stir to form aluminum alcohol solution, then add graphite powder and low-temperature microwave reaction for 2 h, filter and dry to obtain coated graphite powder, the concentration of aluminum isopropyl alcohol in ethanol is 100 g / L, the stirring speed is 500 r / min, the concentration of graphite powder in aluminum alcohol solution is 150 g / L, the temperature of low-temperature microwave reaction is 30℃, and the microwave power is 300 W; the drying temperature is 100℃, and the drying is carried out in a nitrogen atmosphere;

[0029] Step 3, add acrylamide into the ether-ethanol mixed solution and stir, then add aluminum isopropyl alcohol and form a mixture, then gradually add distilled water and stir until no more distilled water is produced to obtain a preliminary slurry; the volume ratio of ether to ethanol in the ether-ethanol mixed solution is 5:2, the stirring speed is 500 r / min, the addition amount of aluminum isopropyl alcohol is 600% of the mass of acrylamide, and the dropping speed of distilled water is 5 mL / min;

[0030] Step 4, concentrate the preliminary slurry, then dilute with water to form a pre-prepared slurry, then add an initiator and a catalyst, add coated graphite powder and constant temperature reaction to form a pre-prepared gel; the concentration temperature is 30℃, the stirring speed is 400 r / min, the concentration of acrylamide in the pre-prepared slurry is 40 g / L, the initiator is ammonium persulfate, and the addition amount of initiator is 10% of the mass of acrylamide, the catalyst is tetramethyl ethylenediamine, and the addition amount of catalyst is 5% of the mass of acrylamide, and the constant temperature reaction temperature is 80℃;

[0031] Step 5, put the above gel into a mold, slowly heat and keep warm, then cool and demold to obtain a blank, then sinter the blank to obtain a porous alumina ceramic suction disc; the slow heating temperature is 10℃ / min, and the keeping warm temperature is 300℃; the sintering atmosphere is an oxygen-rich atmosphere, and the oxygen content is 35%, and the sintering temperature is 1550℃.

[0032] Example 3

[0033] A method for preparing a porous alumina ceramic suction disc, comprising the following steps:

[0034] Step 1, put the graphite powder into the ethanol aqueous solution for ultrasonic treatment for 30 min, filter and dry to obtain clean graphite powder, the volume ratio of ethanol in the ethanol aqueous solution is 55%, the concentration of graphite powder in the ethanol aqueous solution is 200 g / L, the ultrasonic frequency of ultrasonic treatment is 70 kHz, the temperature is 30℃, and the drying temperature is 130℃; the particle size of the graphite powder is 150 μm;

[0035] Step 2, add aluminum isopropyl alcohol into ethanol and stir to form aluminum alcohol solution, then add graphite powder and low-temperature microwave reaction for 2 h, filter and dry to obtain coated graphite powder, the concentration of aluminum isopropyl alcohol in ethanol is 80 g / L, the stirring speed is 400 r / min, the concentration of graphite powder in aluminum alcohol solution is 130 g / L, the temperature of low-temperature microwave reaction is 25℃, and the microwave power is 200 W; the drying temperature is 95℃, and the drying is carried out in a nitrogen atmosphere;

[0036] Step 3, add acrylamide into the ether-ethanol mixed solution and stir, then add aluminum isopropyl alcohol and form a mixture, then gradually add distilled water and stir until no more distilled water is produced to obtain a preliminary slurry; the volume ratio of ether to ethanol in the ether-ethanol mixed solution is 4:2, the stirring speed is 400 r / min, the amount of aluminum isopropyl alcohol added is 500% of the mass of acrylamide, and the dropping speed of distilled water is 4 mL / min;

[0037] Step 4, concentrate the preliminary slurry, then dilute with water to form a pre-prepared slurry, then add an initiator and a catalyst, add coated graphite powder and constant-temperature reaction to form a pre-prepared gel; the concentration temperature is 25℃, the stirring speed is 300 r / min, the concentration of acrylamide in the pre-prepared slurry is 30 g / L, the initiator is ammonium persulfate, and the amount of initiator added is 8% of the mass of acrylamide, the catalyst is tetramethyl ethylenediamine, and the amount of catalyst added is 4% of the mass of acrylamide, and the constant-temperature reaction temperature is 70℃;

[0038] Step 5, put the above gel into a mold, slowly heat and keep warm, then cool and demold to obtain a blank, then sinter the blank to obtain a porous alumina ceramic suction disc; the slow heating temperature is 8℃ / min, and the holding temperature is 250℃; the sintering atmosphere is an oxygen-rich atmosphere, and the oxygen content is 32%, and the sintering temperature is 1400℃.

[0039] The product of Example 1 is used as a test example, and a commercially available product with similar porosity is used as a comparative example for performance testing, as shown in Table 1, and the actual picture of the porous alumina ceramic suction disc with a frame is shown in Figure 1. Figure 1 Figure 2 ​is a scanning electron microscope image of the porous alumina ceramic of this example, with a porosity of 42% and a pore size of 1 pm; performance comparison of example 1 and comparative examples is as follows:

[0040]

[0041] In summary, the present application has the following advantages:

[0042] 1. The present application solves the problem of local gap caused by the inertness of graphite powder, uses the solubility and coating property of aluminum isopropyl alcohol itself to form a homogeneous liquid film structure on the surface of graphite powder, and converts it into aluminum hydroxide through the liquid film, thereby repairing the gap and improving the strength of the alumina ceramic suction cup.

[0043] 2. The present application realizes the miniaturization of aluminum hydroxide by using liquid deposition combined with aluminum isopropyl alcohol hydrolysis, improves the homogeneous dispersion of aluminum hydroxide in polyacrylamide, and thus improves the homogeneous dispersion on the alumina ceramic suction cup.

[0044] 3. The present application utilizes the condensation reaction of aluminum hydroxide in the gel and on the surface of the plated graphite during the heat preservation treatment, effectively ensures the integration of the aluminum hydroxide material, ensures local condensation shrinkage, and reduces the formation of gaps.

[0045] It can be understood that the above specific description of the present application is only used to illustrate the present application and is not limited to the technical solutions described in the embodiments of the present application. Those skilled in the art should understand that the present application can still be modified or replaced equivalently to achieve the same technical effect; as long as it meets the needs of use, it is within the protection scope of the present application.

Claims

1. A method of making a porous alumina ceramic suction cup, characterized by: It comprises the following steps: Step 1, put the graphite powder into the ethanol aqueous solution and ultrasonic treatment for 20-40 min, filter and dry to obtain the clean surface graphite powder; Step 2, add the aluminum isopropyl alcohol into the ethanol and stir to form the aluminum alcohol liquid, then add the graphite powder and low-temperature microwave reaction for 1-2 h, filter and dry to obtain the coated graphite powder; the concentration of the aluminum isopropyl alcohol in the ethanol is 50-100 g / L, the stirring speed is 300-500 r / min, the concentration of the graphite powder in the aluminum alcohol liquid is 100-150 g / L, the temperature of the low-temperature microwave reaction is 20-30℃, the microwave power is 100-300 W, the drying temperature is 90-100℃, and the drying is carried out in the nitrogen atmosphere; Step 3, add the acrylamide into the diethyl ether ethanol mixed solution and stir to form the mixture, then gradually add the distilled water and stir until no more distilled water is produced to obtain the preliminary slurry; Step 4, add water to the preliminary slurry to form the pre-prepared slurry, then add the initiator and catalyst, add the coated graphite powder and constant temperature reaction to form the pre-prepared gel; Step 5, put the gel into the mold, slowly heat and keep warm, after cooling and demolding, obtain the blank, sinter the blank to obtain the porous alumina ceramic suction disc.

2. The method of claim 1, wherein: The volume ratio of the ethanol in the ethanol aqueous solution in the step 1 is 50-60%, the concentration of the graphite powder in the ethanol aqueous solution is 100-400 g / L, the ultrasonic frequency of the ultrasonic treatment is 50-80 kHz, the temperature is 20-40℃, and the drying temperature is 120-140℃.

3. The method of claim 1, wherein: The particle size of the graphite powder in the step 1 is 1-300 μm.

4. The method of claim 1, wherein: The volume ratio of the diethyl ether and ethanol in the diethyl ether ethanol mixed solution in the step 3 is 3-5:2, the stirring speed is 300-500 r / min, the addition amount of the aluminum isopropyl alcohol is 400-600% of the mass of the acrylamide, and the dropping speed of the distilled water is 3-5 mL / min.

5. The method of claim 1, wherein: The concentration of the acrylamide in the pre-prepared slurry in the step 4 is 20-40 g / L, the initiator is ammonium persulfate, and the addition amount of the initiator is 5-10% of the mass of the acrylamide, the catalyst is tetramethyl ethylenediamine, and the addition amount of the catalyst is 2-5% of the mass of the acrylamide, and the constant temperature reaction temperature is 60-80℃.

6. The method of claim 1, wherein: The slow heating temperature in the step 5 is 4-10℃ / min, and the holding temperature is 200-300℃; the atmosphere of the sintering treatment is the oxygen-rich atmosphere, and the oxygen content is 30-35%, and the sintering treatment temperature is 1250-1550℃.

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