Pressureless sintering aluminum nitride polishing method

Abstract

The invention discloses a pressureless sintering aluminum nitride polishing method, and aims to overcome the defect that the requirement of high-precision batch production of aluminum nitride is difficult to meet by an existing polishing process. The method comprises the following steps: S1, calendaring the surface of an aluminum nitride sample block by a surface grinding machine until the roughness is Ra 0.8 or below; s2, the surface of the aluminum nitride sample block is polished by a plane polishing machine until the roughness is Ra0.3 or below, diamond micro-powder serves as polishing powder, and a copper disc makes contact with the surface of the aluminum nitride sample block for polishing; and S3, the surface of the aluminum nitride sample block is polished by a plane polishing machine until the roughness Ra is lower than 0.05, aluminum oxide micro powder serves as polishing powder, and a polishing pad makes contact with the surface of the aluminum nitride sample block for polishing. According to the pressureless sintering aluminum nitride polishing method, pressureless sintering aluminum nitride high-precision polishing can be achieved, the requirement for batch production is met, the roughness of a polished product can reach Ra0.05 or below, and the product is good in performance and long in service life.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic processing, and more particularly to a polishing method for pressureless sintered aluminum nitride. Background Art

[0002] Aluminum nitride is a high-temperature wear-resistant material with the advantages of wear resistance, high thermal conductivity, good light transmission characteristics, excellent electrical properties (dielectric constant, dielectric loss, volume resistivity, dielectric strength), and good mechanical properties. It is widely used in aerospace, energy, electronics, machinery and other fields. Aluminum nitride polishing technology is one of the important means to improve the surface finish and flatness of aluminum nitride materials.

[0003] The principle of aluminum nitride surface polishing is to reduce the surface roughness to a certain range and achieve a certain degree of finish through mechanical grinding or chemical reaction. The surface polishing of aluminum nitride can be done by mechanical polishing, chemical polishing or physical vapor polishing. However, due to the material properties of aluminum nitride, the surface is more sparse than that of aluminum oxide. The existing polishing process method is difficult to perform high-precision batch polishing to a surface roughness below Ra0.05, and it is difficult to achieve the requirements of high-precision batch production of aluminum nitride. Summary of the invention

[0004] In order to overcome the above-mentioned shortcomings, the present invention provides a pressureless sintered aluminum nitride polishing method, which can achieve high-precision polishing of pressureless sintered aluminum nitride to meet the needs of mass production. The roughness of the product after polishing can reach below Ra0.05, and the product has good performance and long service life.

[0005] In order to solve the above technical problems, the present invention adopts the following technical scheme: a pressureless sintered aluminum nitride polishing method, comprising the following steps: S1, a surface grinder calenders the surface of the aluminum nitride sample to a roughness of less than Ra0.8; S2, a surface polisher polishes the surface of the aluminum nitride sample to a roughness of less than Ra0.3, diamond micropowder is used as polishing powder, and a copper disk is in contact with the surface of the aluminum nitride sample for polishing; S3, a surface polisher polishes the surface of the aluminum nitride sample to a roughness of less than Ra0.05, alumina micropowder is used as polishing powder, and a polishing pad is in contact with the surface of the aluminum nitride sample for polishing.

[0006] When polishing the aluminum nitride sample, first use a surface grinder to calender the surface so that the surface roughness reaches below Ra0.8. Then use a flat polishing machine for further polishing. The flat polishing machine first uses diamond powder as polishing powder. The aluminum nitride sample is placed on a rotating copper disk. The diamond powder is mixed in the polishing liquid and sprinkled on the surface of the copper disk. The copper disk contacts the surface of the aluminum nitride sample and rotates and polishes each other to reduce the surface roughness of the aluminum nitride sample. Then, the flat polishing machine uses aluminum oxide powder as polishing powder. The aluminum nitride sample is placed on a rotating copper disk. At this time, a polishing pad is set on the copper disk. The aluminum oxide powder is mixed in the polishing liquid and sprinkled on the surface of the polishing pad. The polishing pad contacts the surface of the aluminum nitride sample and rotates and polishes each other to further reduce the surface roughness of the aluminum nitride sample and meet production requirements.

[0007] The pressureless sintered aluminum nitride polishing method of this patent application can achieve high-precision polishing of pressureless sintered aluminum nitride to meet the needs of mass production. The roughness of the product after polishing can reach below Ra0.05, and the product has good performance and long service life.

[0008] Preferably, both surfaces of the aluminum nitride sample in S1 are calendered simultaneously or individually.

[0009] The aluminum nitride sample is subjected to single-sided calendering operation or double-sided calendering operation according to production requirements. When the double-sided calendering operation is performed, the calendering operation on one side is completed and then the calendering operation on the other side is performed.

[0010] Preferably, a 750-850 mesh diamond grinding wheel is used for processing in S1.

[0011] The 750-850 mesh diamond grinding wheel has a good calendering effect on the aluminum nitride sample. After processing, the surface roughness of the aluminum nitride sample can reach below Ra0.8.

[0012] Preferably, after the aluminum nitride sample in S1 is processed, the flatness is controlled below 0.01, and the parallelism is controlled below 0.02.

[0013] After the aluminum nitride sample is calendered by a surface grinder, its flatness and parallelism meet certain requirements, which is conducive to ensuring the subsequent overall polishing effect.

[0014] Preferably, the S2 process is divided into two steps. The first step is to use 6-9um diamond powder, process for 55-65 minutes, polish with a weight of 8-10kg, and polish the surface of the aluminum nitride sample to a roughness of Ra0.3-Ra0.4; the second step is to use 2-4um diamond powder, process for 110-130 minutes, polish with a weight of 8-10kg, and polish the surface of the aluminum nitride sample to a roughness of Ra0.2-Ra0.3.

[0015] The S2 process is completed in two steps. The first step is to use relatively coarse diamond powder to polish the aluminum nitride sample surface to a roughness of Ra0.3-Ra0.4; the second step is to use relatively fine diamond powder to polish the aluminum nitride sample surface to a roughness of Ra0.2-Ra0.3. Polishing in steps reduces the surface roughness in sequence, which is conducive to improving the polishing effect.

[0016] Preferably, the S3 process is divided into four steps, the particle size of the alumina powder is reduced successively, and the surface roughness of the aluminum nitride sample is reduced successively.

[0017] The S3 process is divided into four steps for polishing, and according to the order of polishing, the particles of alumina powder are reduced successively, and the surface roughness of the aluminum nitride sample after polishing is reduced successively, which is beneficial to improve the polishing effect and meet the production requirements.

[0018] Preferably, the first three steps use damping cloth as the polishing pad, and the fourth step uses plant fleece as the polishing pad.

[0019] The damping cloth polishing pad is a velvety polishing material with a fine texture, soft surface, and covered with small holes. It can hold the polishing liquid well when used, increasing the cutting force while avoiding scratching the workpiece.

[0020] The plant velvet polishing pad is soft in texture and can fit the surface of the object being polished well during the polishing process to avoid deep scratches on it, and it has a long service life. It has a certain elasticity and can undergo elastic deformation when under pressure, so that the polishing liquid can better enter the gap between the velvet and be stored; after the pressure is released, it can return to its original state, discharge the old polishing liquid and reactants, and add new polishing liquid, so as to ensure the continuous and effective polishing process. When the polishing pad contacts the surface of the object, it can provide a more uniform and delicate polishing effect, which helps to obtain a smooth and flat surface, reduce the surface roughness, and make the polished object present a good mirror effect, meeting the needs of high-precision polishing. The fiber structure of plant velvet is relatively loose, with more pores and velvet gaps, which can accommodate and store a large amount of polishing liquid. During the polishing process, it can continuously and stably provide sufficient polishing liquid to the polishing area, ensuring the consistency of the polishing effect and improving the polishing efficiency.

[0021] Preferably, the first step is processed for 110-130 minutes, with a polishing weight of 4.5-5.5kg; the second step is processed for 230-250 minutes, with a polishing weight of 3-4kg; the third step is processed for 350-370 minutes, with a polishing weight of 3-4kg; the fourth step is processed for 350-370 minutes, with a polishing weight of 1-2kg.

[0022] The four steps of the S3 process use different processing times and weights to achieve the best polishing effect.

[0023] Preferably, a feeding cylinder is installed on the plane polishing machine, and a plurality of storage cavities are arranged at circumferential intervals inside the feeding cylinder, a discharge hole is arranged at the bottom of the storage cavity, a valve plate is installed at the bottom of the feeding cylinder, the valve plate is rotatably arranged, a discharge hole is arranged on the valve plate, and a discharge hole is arranged at the bottom of the feeding cylinder. A plurality of polishing powders are respectively loaded in a plurality of storage cavities, and the valve plate is rotated to connect the discharge hole with the discharge holes at different positions to realize the switching of discharge.

[0024] In the step of polishing the aluminum nitride sample, the types and particle sizes of the polishing powders used are different. At this time, different polishing powders are loaded in different storage chambers and mixed with the polishing liquid. When a certain polishing powder is needed, the valve plate is rotated to make the feed hole correspond to the discharge hole corresponding to the polishing powder. At this time, the polishing powder falls onto the copper plate together with the polishing liquid through the discharge hole, feed hole, and drop hole for use. Through the setting of this structural feeding cylinder, different polishing powders can be added at one time, without the need to manually change different polishing powders each time, which facilitates operation, helps to improve work efficiency, and reduces labor intensity.

[0025] Preferably, a plurality of annular polishing areas are provided on the upper surface of the copper disk, and different polishing pads are installed in different polishing areas; a V-shaped object blocking rack is provided in each polishing area, and the object blocking rack includes a fixed rod and a rotating rod, and rotating columns are installed on the fixed rod and the rotating rod, and the object blocking rack blocks and positions the aluminum nitride sample loaded in the polishing area. After the aluminum nitride sample is polished in the inner polishing area, the rotating rod rotates, and under the action of centrifugal force, the aluminum nitride sample is offset to the outer polishing area and is blocked and positioned by the object blocking rack for polishing.

[0026] The aluminum nitride sample needs to be polished on different polishing pads. The traditional method requires stopping the machine, removing the original polishing pad on the copper plate and replacing it with a new one, and then starting polishing. However, by setting different polishing areas, non-stop polishing can be achieved. After the aluminum nitride sample is polished in the inner polishing area, the rotating rod rotates, and the rotating column on the rotating rod removes the limit on the aluminum nitride sample. Under the action of centrifugal force, the aluminum nitride sample is offset to the outer polishing area and is blocked by the blocking rack for positioning and polishing.

[0027] Compared with the prior art, the beneficial effects of the present invention are: (1) The pressureless sintered aluminum nitride polishing method of the patent application can achieve high-precision polishing of pressureless sintered aluminum nitride, meet the needs of mass production, and the roughness of the product after polishing can reach below Ra0.05, with good product performance and long service life; (2) The polishing powder can be added once, without the need to manually replace different polishing powders each time, which facilitates operation, helps to improve work efficiency and reduce labor intensity; (3) The copper plate can achieve non-stop operation when polishing aluminum nitride, which improves work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the copper disk installation of Example 1 of the present invention.

[0029] Figure 2 It is a structural diagram of the feeding cylinder of Example 2 of the present invention.

[0030] Figure 3 It is a schematic diagram of the copper disk installation of Example 3 of the present invention.

[0031] In the figure: 1. aluminum nitride sample, 2. plane polishing machine, 3. counterweight, 4. copper plate, 5. positioning sleeve, 6. limit frame, 7. rotating wheel, 8. damping cloth, 9. plant fleece, 10. feeding cylinder, 11. storage chamber, 12. discharge hole, 13. valve plate, 14. feed hole, 15. drop hole, 16. driving motor, 17. gear, 18. meshing teeth, 19. polishing area, 20. stop frame, 21. fixed rod, 22. rotating rod, 23. rotating column, 24. outer rotating ring, 25. inner rotating ring. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings: Example 1: A method for polishing pressureless sintered aluminum nitride (see Figure 1 ), including the following steps: S1, a surface grinder calenders the surface of the aluminum nitride sample 1 to a roughness of less than Ra0.8; in S1, both surfaces of the aluminum nitride sample 1 are calendered simultaneously or separately. The aluminum nitride sample 1 is calendered on one side or on both sides according to production requirements. When the two sides are calendered, the calendering operation on one side is completed, and then the calendering operation on the other side is turned over. A 750-850 mesh diamond grinding wheel is used for processing. In this embodiment, an 800 mesh diamond grinding wheel is used for processing. After the processing, the flatness of the aluminum nitride sample 1 is controlled below 0.01, and the parallelism is controlled below 0.02. After the aluminum nitride sample 1 is calendered by a surface grinder, the flatness and parallelism meet certain requirements, which is conducive to ensuring the subsequent overall polishing effect.

[0033] S2, the plane polishing machine 2 polishes the surface of the aluminum nitride sample 1 to a roughness of less than Ra0.3, diamond powder is used as polishing powder, and the copper plate 4 contacts and polishes the surface of the aluminum nitride sample 1. The S2 process is divided into two steps, the diamond powder particles are reduced successively, and the surface roughness of the aluminum nitride sample 1 is reduced successively. Specifically, the first step uses 6-9um diamond powder, the processing time is 55-65 minutes, the polishing weight is 38-10kg, and the surface of the aluminum nitride sample 1 is polished to a roughness of Ra0.3-Ra0.4; the second step uses 2-4um diamond powder, the processing time is 110-130 minutes, the polishing weight is 38-10kg, and the surface of the aluminum nitride sample 1 is polished to a roughness of Ra0.2-Ra0.3. In this embodiment, the first step uses 6um diamond powder, processes for 60 minutes, polishes with a weight of 38kg, and polishes the surface of the aluminum nitride sample 1 to a roughness of Ra0.3-Ra0.4; the second step uses 3um diamond powder, processes for 120 minutes, polishes with a weight of 38kg, and polishes the surface of the aluminum nitride sample 1 to a roughness of Ra0.2-Ra0.3.

[0034] During the S2 polishing operation, the aluminum nitride sample 1 is placed on the rotating copper disk 4, and the diamond powder is mixed with the polishing liquid and sprinkled onto the surface of the copper disk 4. The counterweight 3 is directly placed on the aluminum nitride sample 1, and the counterweight 3 is positioned by the positioning sleeve 5 arranged above the aluminum nitride sample 1 to prevent it from slipping. A limit frame 6 is arranged above the copper disk 4, and a rotating wheel 7 is installed on the limit frame 6. The aluminum nitride sample 1 is positioned against the rotating wheel 7. The copper disk 4 contacts the surface of the aluminum nitride sample 1 and rotates with each other to polish, thereby reducing the surface roughness of the aluminum nitride sample 1.

[0035] S3, the plane polishing machine 2 polishes the surface of the aluminum nitride sample 1 to a roughness of less than Ra0.05, and the aluminum oxide micropowder is used as the polishing powder. The polishing pad contacts and polishes the surface of the aluminum nitride sample 1. The S3 process is divided into four steps. The particles of the aluminum oxide micropowder decrease successively, and the surface roughness of the aluminum nitride sample 1 decreases successively. The damping cloth 8 is used as the polishing pad in the first three steps, and the plant fleece 9 is used as the polishing pad in the fourth step. The first step is processed for 110-130 minutes, and the polishing weight is 34.5-5.5kg; the second step is processed for 230-250 minutes, and the polishing weight is 33-4kg; the third step is processed for 350-370 minutes, and the polishing weight is 33-4kg; the fourth step is processed for 350-370 minutes, and the polishing weight is 31-2kg.

[0036] Specifically, the first step: use 1um alumina powder as polishing powder, damping cloth 8 as polishing pad, processing time 120min, counterweight 35kg, and polish the surface of aluminum nitride sample 1 to a roughness of less than Ra0.2. The second step: use 0.75um alumina powder as polishing powder, damping cloth 8 as polishing pad, processing time 240min, counterweight 33.6kg, and polish the surface of aluminum nitride sample 1 to a roughness of less than Ra0.1. The third step: use 0.3um alumina powder as polishing powder, damping cloth 8 as polishing pad, processing time 360min, counterweight 33.6kg, and polish the surface of aluminum nitride sample 1 to a roughness of about Ra0.05. Step 4: Use 0.1um alumina powder as polishing powder and plant fleece 9 as polishing pad, process for 360min, and use counterweight of 31.5kg. This step does not require the addition of 3 additional counterweights. The deadweight of aluminum nitride sample 1 can meet the requirement of counterweight 3. Polish the surface of aluminum nitride sample 1 to a roughness of less than Ra0.05.

[0037] During the S3 polishing operation, a polishing pad is glued on the copper disk 4, and the aluminum nitride sample 1 is placed on the polishing pad. Alumina powder is mixed into the polishing liquid and sprinkled onto the surface of the polishing pad. The counterweight 3 is directly placed on the aluminum nitride sample 1. The counterweight 3 is positioned by the positioning sleeve 5 provided above the aluminum nitride sample 1 to prevent it from slipping. The polishing pad contacts the surface of the aluminum nitride sample 1 and rotates with each other to polish, thereby reducing the surface roughness of the aluminum nitride sample 1.

[0038] When the aluminum nitride sample 1 is polished, a surface grinder is first used to calender the surface so that the surface roughness reaches below Ra0.8. Then, a plane polishing machine 2 is used for further polishing. The plane polishing machine 2 first uses diamond powder as polishing powder. The aluminum nitride sample 1 is placed on a rotating copper disk 4. The diamond powder is mixed in the polishing liquid and sprinkled on the surface of the copper disk 4. The copper disk 4 contacts the surface of the aluminum nitride sample 1 and rotates and polishes each other to reduce the surface roughness of the aluminum nitride sample 1. Then, the plane polishing machine 2 uses aluminum oxide powder as polishing powder. The aluminum nitride sample 1 is placed on the rotating copper disk 4. At this time, a polishing pad is set on the copper disk 4. The aluminum oxide powder is mixed in the polishing liquid and sprinkled on the surface of the polishing pad. The polishing pad contacts the surface of the aluminum nitride sample 1 and rotates and polishes each other to further reduce the surface roughness of the aluminum nitride sample 1 to meet production requirements.

[0039] Example 2: A method for polishing pressureless sintered aluminum nitride (see Figure 1), including the following steps: S1, a surface grinder calenders the surface of the aluminum nitride sample 1 to a roughness of less than Ra0.8; in S1, both surfaces of the aluminum nitride sample 1 are calendered simultaneously or separately. The aluminum nitride sample 1 is calendered on one side or on both sides according to production requirements. When the two sides are calendered, the calendering operation on one side is completed, and then the calendering operation on the other side is turned over. A 750-850 mesh diamond grinding wheel is used for processing. In this embodiment, an 800 mesh diamond grinding wheel is used for processing. After the processing, the flatness of the aluminum nitride sample 1 is controlled below 0.01, and the parallelism is controlled below 0.02. After the aluminum nitride sample 1 is calendered by a surface grinder, the flatness and parallelism meet certain requirements, which is conducive to ensuring the subsequent overall polishing effect.

[0040] S2, the plane polishing machine 2 polishes the surface of the aluminum nitride sample 1 to a roughness of less than Ra0.3, diamond powder is used as polishing powder, and the copper plate 4 contacts and polishes the surface of the aluminum nitride sample 1. The S2 process is divided into two steps, the diamond powder particles are reduced successively, and the surface roughness of the aluminum nitride sample 1 is reduced successively. Specifically, the first step uses 6-9um diamond powder, the processing time is 55-65 minutes, the polishing weight is 38-10kg, and the surface of the aluminum nitride sample 1 is polished to a roughness of Ra0.3-Ra0.4; the second step uses 2-4um diamond powder, the processing time is 110-130 minutes, the polishing weight is 38-10kg, and the surface of the aluminum nitride sample 1 is polished to a roughness of Ra0.2-Ra0.3. In this embodiment, the first step uses 6um diamond powder, processes for 60 minutes, polishes with a weight of 38kg, and polishes the surface of the aluminum nitride sample 1 to a roughness of Ra0.3-Ra0.4; the second step uses 3um diamond powder, processes for 120 minutes, polishes with a weight of 38kg, and polishes the surface of the aluminum nitride sample 1 to a roughness of Ra0.2-Ra0.3.

[0041] During the S2 polishing operation, the aluminum nitride sample 1 is placed on the rotating copper disk 4, and the diamond powder is mixed with the polishing liquid and sprinkled onto the surface of the copper disk 4. The counterweight 3 is directly placed on the aluminum nitride sample 1, and the counterweight 3 is positioned by the positioning sleeve 5 arranged above the aluminum nitride sample 1 to prevent it from slipping. A limit frame 6 is arranged above the copper disk 4, and a rotating wheel 7 is installed on the limit frame 6. The aluminum nitride sample 1 is positioned against the rotating wheel 7. The copper disk 4 contacts the surface of the aluminum nitride sample 1 and rotates with each other to polish, thereby reducing the surface roughness of the aluminum nitride sample 1.

[0042] S3, the plane polishing machine 2 polishes the surface of the aluminum nitride sample 1 to a roughness of less than Ra0.05, and the aluminum oxide micropowder is used as the polishing powder. The polishing pad contacts and polishes the surface of the aluminum nitride sample 1. The S3 process is divided into four steps. The particles of the aluminum oxide micropowder decrease successively, and the surface roughness of the aluminum nitride sample 1 decreases successively. The damping cloth 8 is used as the polishing pad in the first three steps, and the plant fleece 9 is used as the polishing pad in the fourth step. The first step is processed for 110-130 minutes, and the polishing weight is 34.5-5.5kg; the second step is processed for 230-250 minutes, and the polishing weight is 33-4kg; the third step is processed for 350-370 minutes, and the polishing weight is 33-4kg; the fourth step is processed for 350-370 minutes, and the polishing weight is 31-2kg.

[0043] Specifically, the first step: use 1um alumina powder as polishing powder, damping cloth 8 as polishing pad, processing time 120min, counterweight 35kg, and polish the surface of aluminum nitride sample 1 to a roughness of less than Ra0.2. The second step: use 0.75um alumina powder as polishing powder, damping cloth 8 as polishing pad, processing time 240min, counterweight 33.6kg, and polish the surface of aluminum nitride sample 1 to a roughness of less than Ra0.1. The third step: use 0.3um alumina powder as polishing powder, damping cloth 8 as polishing pad, processing time 360min, counterweight 33.6kg, and polish the surface of aluminum nitride sample 1 to a roughness of about Ra0.05. Step 4: Use 0.1um alumina powder as polishing powder and plant fleece 9 as polishing pad, process for 360min, and use counterweight of 31.5kg. This step does not require the addition of 3 additional counterweights. The deadweight of aluminum nitride sample 1 can meet the requirement of counterweight 3. Polish the surface of aluminum nitride sample 1 to a roughness of less than Ra0.05.

[0044] During the S3 polishing operation, a polishing pad is glued on the copper disk 4, and the aluminum nitride sample 1 is placed on the polishing pad. Alumina powder is mixed into the polishing liquid and sprinkled onto the surface of the polishing pad. The counterweight 3 is directly placed on the aluminum nitride sample 1. The counterweight 3 is positioned by the positioning sleeve 5 provided above the aluminum nitride sample 1 to prevent it from slipping. The polishing pad contacts the surface of the aluminum nitride sample 1 and rotates with each other to polish, thereby reducing the surface roughness of the aluminum nitride sample 1.

[0045] like Figure 2As shown, a feeding barrel 10 is installed on the plane polishing machine 2, and a plurality of storage chambers 11 are arranged at intervals in the circumferential direction inside the feeding barrel 10, and a discharge hole 12 is arranged at the bottom of the storage chamber 11. A valve plate 13 is installed at the bottom of the feeding barrel 10, and the valve plate 13 is arranged to rotate, and a discharge hole 14 is arranged on the valve plate 13. The feeding barrel 10 below the valve plate 13 is a conical structure with a large top and a small bottom, and a discharge hole 15 is arranged at the bottom of the feeding barrel 10. A driving motor 16 is installed on the outer wall of the feeding barrel 10, and the output shaft of the driving motor 16 is connected to a gear 17. A circle of meshing teeth 18 is arranged on the outer edge of the valve plate 13, and the gear 17 is connected to the meshing teeth 18 in a transmission manner. A variety of polishing powders are loaded in a plurality of storage chambers 11 respectively, and the valve plate 13 rotates to connect the discharge hole 14 with the discharge holes 12 at different positions to realize switching of discharge.

[0046] In the steps of polishing the aluminum nitride sample 1 of S2 and S3, the types and particle sizes of the polishing powders used are different. At this time, different polishing powders are loaded in different storage chambers 11 and mixed with the polishing liquid. In this embodiment, 6um diamond powder, 3um diamond powder, 1um alumina powder, 0.75um alumina powder, 0.3um alumina powder, and 0.1um alumina powder are needed. These different polishing powders are loaded in different storage chambers 11 and mixed with the polishing liquid. When a certain polishing powder is needed, the valve plate 13 is rotated to make the feed hole 14 correspond to the discharge hole 12 corresponding to the polishing powder. At this time, the polishing powder falls to the copper plate 4 through the discharge hole 12, the feed hole 14, and the drop hole 15 together with the polishing liquid for use. Through the setting of this structure of the feeding cylinder 10, different polishing powders can be added at one time, without the need to manually change different polishing powders each time, which facilitates the operation, helps to improve work efficiency, and reduces labor intensity.

[0047] When the aluminum nitride sample 1 is polished, a surface grinder is first used to calender the surface so that the surface roughness reaches below Ra0.8. Then, a plane polishing machine 2 is used for further polishing. The plane polishing machine 2 first uses diamond powder as polishing powder. The aluminum nitride sample 1 is placed on a rotating copper disk 4. The diamond powder is mixed in the polishing liquid and sprinkled on the surface of the copper disk 4. The copper disk 4 contacts the surface of the aluminum nitride sample 1 and rotates and polishes each other to reduce the surface roughness of the aluminum nitride sample 1. Then, the plane polishing machine 2 uses aluminum oxide powder as polishing powder. The aluminum nitride sample 1 is placed on the rotating copper disk 4. At this time, a polishing pad is set on the copper disk 4. The aluminum oxide powder is mixed in the polishing liquid and sprinkled on the surface of the polishing pad. The polishing pad contacts the surface of the aluminum nitride sample 1 and rotates and polishes each other to further reduce the surface roughness of the aluminum nitride sample 1 to meet production requirements.

[0048] Example 3: A method for polishing pressureless sintered aluminum nitride (see Figure 3), including the following steps: S1, a surface grinder calenders the surface of the aluminum nitride sample 1 to a roughness of less than Ra0.8; in S1, both surfaces of the aluminum nitride sample 1 are calendered simultaneously or separately. The aluminum nitride sample 1 is calendered on one side or on both sides according to production requirements. When the two sides are calendered, the calendering operation on one side is completed, and then the calendering operation on the other side is turned over. A 750-850 mesh diamond grinding wheel is used for processing. In this embodiment, an 800 mesh diamond grinding wheel is used for processing. After the processing, the flatness of the aluminum nitride sample 1 is controlled below 0.01, and the parallelism is controlled below 0.02. After the aluminum nitride sample 1 is calendered by a surface grinder, the flatness and parallelism meet certain requirements, which is conducive to ensuring the subsequent overall polishing effect.

[0049] S2, the plane polishing machine 2 polishes the surface of the aluminum nitride sample 1 to a roughness of less than Ra0.3, diamond powder is used as polishing powder, and the copper plate 4 contacts and polishes the surface of the aluminum nitride sample 1. The S2 process is divided into two steps, the diamond powder particles are reduced successively, and the surface roughness of the aluminum nitride sample 1 is reduced successively. Specifically, the first step uses 6-9um diamond powder, the processing time is 55-65 minutes, the polishing weight is 38-10kg, and the surface of the aluminum nitride sample 1 is polished to a roughness of Ra0.3-Ra0.4; the second step uses 2-4um diamond powder, the processing time is 110-130 minutes, the polishing weight is 38-10kg, and the surface of the aluminum nitride sample 1 is polished to a roughness of Ra0.2-Ra0.3. In this embodiment, the first step uses 6um diamond powder, processes for 60 minutes, polishes with a weight of 38kg, and polishes the surface of the aluminum nitride sample 1 to a roughness of Ra0.3-Ra0.4; the second step uses 3um diamond powder, processes for 120 minutes, polishes with a weight of 38kg, and polishes the surface of the aluminum nitride sample 1 to a roughness of Ra0.2-Ra0.3.

[0050] During the S2 polishing operation, the aluminum nitride sample 1 is placed on a rotating copper disk 4, and diamond powder is mixed in the polishing liquid and sprinkled onto the surface of the copper disk 4. The copper disk 4 contacts the surface of the aluminum nitride sample 1 and rotates with each other to polish, thereby reducing the surface roughness of the aluminum nitride sample 1.

[0051] S3, the plane polishing machine 2 polishes the surface of the aluminum nitride sample 1 to a roughness of less than Ra0.05, and the aluminum oxide micropowder is used as the polishing powder. The polishing pad contacts and polishes the surface of the aluminum nitride sample 1. The S3 process is divided into four steps. The particles of the aluminum oxide micropowder decrease successively, and the surface roughness of the aluminum nitride sample 1 decreases successively. The damping cloth 8 is used as the polishing pad in the first three steps, and the plant fleece 9 is used as the polishing pad in the fourth step. The first step is processed for 110-130 minutes, and the polishing weight is 34.5-5.5kg; the second step is processed for 230-250 minutes, and the polishing weight is 33-4kg; the third step is processed for 350-370 minutes, and the polishing weight is 33-4kg; the fourth step is processed for 350-370 minutes, and the polishing weight is 31-2kg.

[0052] Specifically, the first step: use 1um alumina powder as polishing powder, damping cloth 8 as polishing pad, processing time 120min, counterweight 35kg, and polish the surface of aluminum nitride sample 1 to a roughness of less than Ra0.2. The second step: use 0.75um alumina powder as polishing powder, damping cloth 8 as polishing pad, processing time 240min, counterweight 33.6kg, and polish the surface of aluminum nitride sample 1 to a roughness of less than Ra0.1. The third step: use 0.3um alumina powder as polishing powder, damping cloth 8 as polishing pad, processing time 360min, counterweight 33.6kg, and polish the surface of aluminum nitride sample 1 to a roughness of about Ra0.05. Step 4: Use 0.1um alumina powder as polishing powder and plant fleece 9 as polishing pad, process for 360min, and use counterweight of 31.5kg. This step does not require the addition of 3 additional counterweights. The deadweight of aluminum nitride sample 1 can meet the requirement of counterweight 3. Polish the surface of aluminum nitride sample 1 to a roughness of less than Ra0.05.

[0053] During the S3 polishing operation, a polishing pad is glued on the copper disk 4, and the aluminum nitride sample 1 is placed on the polishing pad. Aluminum oxide powder is mixed into the polishing liquid and sprinkled onto the surface of the polishing pad. The polishing pad contacts the surface of the aluminum nitride sample 1 and rotates with each other to polish, thereby reducing the surface roughness of the aluminum nitride sample 1.

[0054] like Figure 3As shown, a plurality of annular polishing areas 19 are arranged on the upper surface of the copper plate 4, and different polishing pads are installed in different polishing areas 19; a V-shaped object blocking rack 20 is arranged in each polishing area 19, and the object blocking rack 20 includes a fixed rod 21 and a rotating rod 22, and a rotating column 23 is installed on each of the fixed rod 21 and the rotating rod 22, and a plurality of guide columns are installed on the fixed rod 21, and the object blocking rack 20 blocks and positions the aluminum nitride sample 1 loaded in the polishing area 19. A deflection motor is installed on the fixed rod 21, and a rotating shaft is installed on the fixed rod 21, and the rotating rod 22 is fixedly connected to the rotating shaft, and the output shaft of the deflection motor is connected to the rotating shaft, and the rotation of the output shaft of the deflection motor drives the rotating rod 22 to rotate. After the aluminum nitride sample 1 is polished in the inner polishing area 19, the rotating rod 22 rotates, and under the action of centrifugal force, the aluminum nitride sample 1 deviates to the outer polishing area 19, is blocked and positioned by the object blocking rack 20, and is polished.

[0055] A V-shaped stopper 20 is installed near the edge of the innermost polishing area 19 in the middle of the copper plate 4. Two circles of polishing areas 19 are set on the copper plate 4. The inner circle polishing area 19 is installed with a damping cloth 8 polishing pad, and the outer circle polishing area 19 is installed with a plant fleece 9 polishing pad. The plane polishing machine 2 is installed with an outer rotating ring 24 and an inner rotating ring 25 that are rotatably arranged. Multiple stoppers 20 are arranged in each polishing area 19. The stoppers 20 of the outer circle polishing area 19 are all connected to the outer rotating ring 24, and the stoppers 20 of the inner circle polishing area 19 are all connected to the inner rotating ring 25. The polishing time of the aluminum nitride sample 1 on the surface of the copper plate 4 and different polishing areas 19 is different, so different numbers of stoppers 20 are arranged in different areas. In this embodiment, a stopper 20 is installed near the edge of the innermost polishing area 19 in the middle of the copper plate 4, four stoppers 20 are installed in the inner circle polishing area 19, and two stoppers 20 are installed in the outer circle polishing area 19. The outer rotating ring 24 and the inner rotating ring 25 can rotate. During S2 and S3, the counterweight 3 is directly placed on the aluminum nitride sample 1, and the counterweight 3 is blocked and limited by the stopper 20. After the aluminum nitride sample 1 is polished on the innermost copper plate 4, the inner rotating ring 25 rotates to make the unloaded stopper 20 on the inner ring polishing area 19 close to the aluminum nitride sample 1, and the rotating rod 22 rotates, and the rotating column 23 on the rotating rod 22 removes the limit on the aluminum nitride sample 1. Under the action of centrifugal force, the aluminum nitride sample 1 is offset to the inner ring polishing area 19 and polished in the polishing area 19. After the aluminum nitride sample 1 is polished in the inner ring polishing area 19, the outer rotating ring 24 rotates to make the unloaded blocking rack 20 on the outer ring polishing area 19 close to the aluminum nitride sample 1, and the rotating rod 22 rotates. The rotating column 23 on the rotating rod 22 removes the limit on the aluminum nitride sample 1. Under the action of centrifugal force, the aluminum nitride sample 1 is offset to the outer ring polishing area 19 and polished in the polishing area 19.

[0056] like Figure 2As shown, a feeding barrel 10 is installed on the plane polishing machine 2, and a plurality of storage chambers 11 are arranged at intervals in the circumferential direction inside the feeding barrel 10, and a discharge hole 12 is arranged at the bottom of the storage chamber 11. A valve plate 13 is installed at the bottom of the feeding barrel 10, and the valve plate 13 is arranged to rotate, and a discharge hole 14 is arranged on the valve plate 13. The feeding barrel 10 below the valve plate 13 is a conical structure with a large top and a small bottom, and a discharge hole 15 is arranged at the bottom of the feeding barrel 10. A driving motor 16 is installed on the outer wall of the feeding barrel 10, and the output shaft of the driving motor 16 is connected to a gear 17. A circle of meshing teeth 18 is arranged on the outer edge of the valve plate 13, and the gear 17 is connected to the meshing teeth 18 in a transmission manner. A variety of polishing powders are loaded in a plurality of storage chambers 11 respectively, and the valve plate 13 rotates to connect the discharge hole 14 with the discharge holes 12 at different positions to realize switching of discharge.

[0057] In the polishing steps of the aluminum nitride sample 1 of S2 and S3, the types and particle sizes of the polishing powders used are different. At this time, different polishing powders are loaded in different storage chambers 11 and mixed with the polishing liquid. In this embodiment, 6um diamond powder, 3um diamond powder, 1um alumina powder, 0.75um alumina powder, 0.3um alumina powder, and 0.1um alumina powder are required, and three different areas are set on the copper plate 4 for polishing, so three corresponding feeding tubes 10 are set. The feeding tube 10 corresponding to the middle of the copper plate 4 adds 6um diamond powder and 3um diamond powder to different storage chambers 11 and mixes with the polishing liquid, and the feeding tube 10 corresponding to the inner ring polishing area 19 adds 1um alumina powder, 0.75um alumina powder, and 0.3um alumina powder to different storage chambers 11 and mixes with the polishing liquid, and the feeding tube 10 of the outer ring adds 0.1um alumina powder to the storage chamber 11 and mixes with the polishing liquid.

[0058] When a certain polishing powder is needed, the valve plate 13 is rotated to make the feed hole 14 correspond to the discharge hole 12 corresponding to the polishing powder, and the polishing powder falls to the copper plate 4 through the discharge hole 12, the feed hole 14 and the drop hole 15 together with the polishing liquid for use. Through the arrangement of the feeding cylinder 10 of this structure, different polishing powders can be added at one time, without the need to manually change different polishing powders each time, which facilitates the operation, helps to improve work efficiency and reduce labor intensity.

[0059] When the aluminum nitride sample 1 is polished, a surface grinder is first used to calender the surface so that the surface roughness reaches below Ra0.8. Then, a plane polishing machine 2 is used for further polishing. The plane polishing machine 2 first uses diamond powder as polishing powder. The aluminum nitride sample 1 is placed on a rotating copper disk 4. The diamond powder is mixed in the polishing liquid and sprinkled on the surface of the copper disk 4. The copper disk 4 contacts the surface of the aluminum nitride sample 1 and rotates and polishes each other to reduce the surface roughness of the aluminum nitride sample 1. Then, the plane polishing machine 2 uses aluminum oxide powder as polishing powder. The aluminum nitride sample 1 is placed on the rotating copper disk 4. At this time, a polishing pad is set on the copper disk 4. The aluminum oxide powder is mixed in the polishing liquid and sprinkled on the surface of the polishing pad. The polishing pad contacts the surface of the aluminum nitride sample 1 and rotates and polishes each other to further reduce the surface roughness of the aluminum nitride sample 1 to meet production requirements.

[0060] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A pressureless sintered aluminum nitride polishing method, characterized in that: The following steps are involved: S1, the surface grinder calenders the surface of the aluminum nitride sample to a roughness of less than Ra0.8; S2, the surface polisher polishes the surface of the aluminum nitride sample to a roughness of less than Ra0.3, diamond micropowder is used as polishing powder, and the copper disk is in contact with the surface of the aluminum nitride sample for polishing; S3, the surface polisher polishes the surface of the aluminum nitride sample to a roughness of less than Ra0.05, alumina micropowder is used as polishing powder, and the polishing pad is in contact with the surface of the aluminum nitride sample for polishing.

2. A pressureless sintered aluminum nitride polishing method according to claim 1, characterized in that: In S1, both surfaces of the aluminum nitride sample are calendered simultaneously or separately.

3. A pressureless sintered aluminum nitride polishing method according to claim 1, characterized in that: In S1, a 750-850 mesh diamond grinding wheel is used for processing.

4. A pressureless sintered aluminum nitride polishing method according to claim 1, characterized in that: After the aluminum nitride sample in S1 is processed, the flatness is controlled below 0.01, and the parallelism is controlled below 0.

02.

5. The method for polishing pressureless sintered aluminum nitride according to claim 1, characterized in that: The S2 process is divided into two steps. The first step uses 6-9um diamond powder, processes for 55-65 minutes, polishes with a weight of 8-10kg, and polishes the surface of the aluminum nitride sample to a roughness of Ra0.3-Ra0.4; the second step uses 2-4um diamond powder, processes for 110-130 minutes, polishes with a weight of 8-10kg, and polishes the surface of the aluminum nitride sample to a roughness of Ra0.2-Ra0.

3.

6. A pressureless sintered aluminum nitride polishing method according to claim 1, characterized in that: The S3 process is divided into four steps, the particle size of alumina powder decreases successively, and the surface roughness of aluminum nitride specimens decreases successively.

7. A pressureless sintered aluminum nitride polishing method according to claim 6, characterized in that: The first three steps use damping cloth as the polishing pad, and the fourth step uses plant fleece as the polishing pad.

8. A pressureless sintered aluminum nitride polishing method according to claim 6, characterized in that: The first step takes 110-130 minutes, with a polishing weight of 4.5-5.5kg; the second step takes 230-250 minutes, with a polishing weight of 3-4kg; the third step takes 350-370 minutes, with a polishing weight of 3-4kg; the fourth step takes 350-370 minutes, with a polishing weight of 1-2kg.

9. A pressureless sintered aluminum nitride polishing method according to any one of claims 1 to 8, characterized in that: A feeding cylinder is installed on the plane polishing machine. A plurality of storage cavities are arranged at circumferential intervals inside the feeding cylinder. A discharge hole is arranged at the bottom of the storage cavity. A valve plate is installed at the bottom of the feeding cylinder. The valve plate is rotatably arranged. A discharge hole is arranged on the valve plate. A discharge hole is arranged at the bottom of the feeding cylinder. Various polishing powders are loaded in multiple storage cavities respectively. The valve plate is rotated to connect the discharge hole with the discharge holes at different positions to realize the switching of discharge.

10. A pressureless sintered aluminum nitride polishing method according to any one of claims 1 to 8, characterized in that: Several annular polishing areas are arranged on the upper surface of the copper plate, and different polishing pads are installed in different polishing areas; V-shaped object blocking racks are arranged in each polishing area, and the object blocking racks include a fixed rod and a rotating rod, and rotating columns are installed on the fixed rod and the rotating rod, and the object blocking racks block and position the aluminum nitride sample loaded in the polishing area. After the aluminum nitride sample is polished in the inner polishing area, the rotating rod rotates, and under the action of centrifugal force, the aluminum nitride sample is offset to the outer polishing area and is blocked and positioned by the object blocking rack for polishing.

Images