A method for producing a polycrystalline diamond micro powder for grinding and / or polishing, products formed therefrom and uses

Abstract

The application relates to the field of finishing, and provides a preparation method of polycrystalline diamond micro powder for grinding and / or polishing, a product formed by the method and an application, the preparation method comprising the following steps: S1, providing polycrystalline diamond as raw material; S2, crushing the polycrystalline diamond to form micro powder to be classified; and S3, classifying the micro powder to be classified to form batches of polycrystalline diamond micro powder. The application creatively proposes a preparation process of a new type of polycrystalline diamond micro powder, the prepared polycrystalline diamond micro powder has good crystal type and good self-sharpening, and can be widely applied to the fields of grinding and polishing of semiconductor devices. Compared with a traditional blasting method, the method is convenient and controllable, the prepared micro powder has a larger particle size, the production efficiency is high, the production site is limited low, and the method is safe and reliable.

Description

Technical Field

[0001] This invention belongs to the field of precision machining, and provides a method for preparing polycrystalline diamond micro powder for grinding and / or polishing, as well as products formed therefrom and their uses. Background Technology

[0002] Polycrystalline diamond powder is composed of micron and submicron-sized polycrystalline materials made up of nanocrystals. Due to its isotropy, lack of cleavage planes, high impact strength, and high bending strength, polycrystalline materials possess both the hardness of superhard materials and the exceptional strength and toughness of nanomaterials. Compared to single-crystal diamond powder, polycrystalline diamond powder has more cutting edges and grinding surfaces, each with cutting capability, resulting in a high removal rate. Polycrystalline diamond powder exhibits toughness and self-sharpening properties, overcoming the drawbacks of hydrostatically synthesized single-crystal diamond, such as brittle fracture of cleavage planes, and soft agglomeration in detonation-processed diamond. Grinding parameters can be adjusted in real time during grinding to perform grinding, fine grinding, and ultra-fine grinding. During grinding and polishing, polycrystalline diamond powder will automatically peel off, revealing new microscopic cutting edges. This excellent self-sharpening property ensures high precision and efficiency in machining without damaging shallow surface layers.

[0003] In existing technologies, polycrystalline diamond micron powder is produced from graphite using a unique directional blasting method. The shock wave from the directional blasting of high-velocity explosives accelerates metal fragments, causing them to collide with graphite flakes and transform the graphite into polycrystalline diamond. Its structure is very similar to natural carbohydrate diamond, with particles composed of tiny diamond grains bonded together by unsaturated bonds, exhibiting excellent toughness. However, this blasting method uses explosives, employs small-particle-size raw materials, and involves high temperatures and pressures during production. Therefore, this method imposes significant limitations on the production site for polycrystalline diamond micron powder, involves hazardous explosives, results in poor crystal structure, and prevents the maximum particle size from reaching the micrometer level. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a new method for preparing polycrystalline diamond micron powder for grinding and / or polishing, as well as the products formed therefrom and their uses. This invention solves the problems of the prior art, such as the large limitations of production sites for polycrystalline diamond micron powder, the involvement of dangerous explosives in the production process, the poor crystal form of the micron powder, and the inability to achieve a maximum particle size of micrometers.

[0005] To achieve the above and other related objectives, the technical solution of the present invention is implemented by including the following technical solutions.

[0006] The first aspect of this invention discloses a method for preparing polycrystalline diamond micron powder, comprising:

[0007] S1. Provide polycrystalline diamond as raw material;

[0008] S2. The polycrystalline diamond is crushed to form micro powder to be graded;

[0009] S3. The polycrystalline diamond after the pulverization process is graded to form multiple batches of polycrystalline diamond micro powder.

[0010] Preferably, in step S1, the polycrystalline diamond is cylindrical.

[0011] Preferably, in step S1, the polycrystalline diamond has an impact toughness Ti value of 65-75 and a thermal shock toughness TTi value of 60-70. For example, the impact toughness Ti value can be 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, or 75; and the thermal shock toughness TTi value can be 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, or 70.

[0012] Preferably, in step S1, the polycrystalline diamond is formed by sintering 5-6 μm polycrystalline diamond particles with a binder.

[0013] Preferably, in step S1, the diameter of the polycrystalline diamond is 20-40 mm, such as 20 mm, 25 mm, 30 mm, 35 mm, or 40 mm.

[0014] Preferably, in step S1, the height of the polycrystalline diamond is 5 to 15 mm, such as 5 mm, 7 mm, 9 mm, 11 mm, 13 mm, or 15 mm.

[0015] Preferably, in S2, the pulverization process includes the following steps:

[0016] 1) Use a jaw crusher to break the polycrystalline diamond into fragments;

[0017] 2) Use a roller mill to crush the fragments into small particles;

[0018] 3) The fragments are ball-milled and shaped.

[0019] More preferably, in step 1), the discharge particle size of the jaw crusher is 6-10 mm, such as 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm.

[0020] More preferably, in step 2), the particle diameter is less than or equal to 2 mm, such as 0.5 mm, 1.0 mm, 1.5 mm, or 2.0 mm.

[0021] More preferably, the ball milling shaping process uses the ball mill jar and a density of 10-20 g / cm³. 3The grinding jar uses steel balls with a hardness of HRC 50-100 for ball milling. Multiple guide rods perpendicular to the inner wall of the grinding jar are provided. Compared to the guide plates used in existing grinding jars, the guide rods used in this application allow the fine powder to pass through, avoiding dead zones, and the spacing between the guide rods helps to move larger steel balls that cannot be moved easily. Using steel balls of specific density and hardness for ball milling greatly increases the impact force.

[0022] More preferably, the grinding jar is made of alloy steel. Using a grinding jar made of alloy steel provides a harder surface suitable for processing polycrystalline diamond micron powder, resulting in better shaping.

[0023] More preferably, the ball mill jar is provided with a rotating shaft fixing component, the rotating shaft fixing component is connected to the rotating shaft, the rotating shaft is connected to the jar lid fixing component, and the jar lid fixing component is connected to the jar lid, so as to facilitate the opening and closing of the jar lid.

[0024] More preferably, the grinding jar is provided with a first guide rod assembly, a second guide rod assembly, a third guide rod assembly, and a fourth guide rod assembly; the guide rods of the first and second guide rod assemblies, the third guide rod assembly, and the fourth guide rod assembly are all staggered. In practice, when steel balls are loaded into the grinding jar, the staggered arrangement of the guide rods of the first and second guide rod assemblies, the third guide rod assembly, and the fourth guide rod assembly creates a moving channel between two vertically adjacent guide rods, causing the steel balls to move along the grinding jar, increasing the frequency of tumbling and impact on the steel balls inside the jar.

[0025] To improve the ball milling effect, most preferably, the included angle of the guide rods of the first and second guide rod assemblies, as well as the guide rods of the third and fourth guide rod assemblies, is 90 degrees.

[0026] More preferably, the ball milling shaping process is carried out at a rotational speed of 40–60 rad / s, such as 40 rad / s, 42 rad / s, 44 rad / s, 46 rad / s, 48 ​​rad / s, 50 rad / s, 52 rad / s, 54 rad / s, 56 rad / s, 58 rad / s, or 60 rad / s. If the rotational speed is too high, the steel balls will be centrifuged to the edge and cannot be broken by impact; if the rotational speed is too low, the impact force of the steel balls will be insufficient to achieve effective crushing.

[0027] More preferably, the ball milling shaping process takes 0.2 to 1 hour, such as 0.2 hours, 0.3 hours, 0.4 hours, 0.5 hours, 0.6 hours, 0.7 hours, 0.8 hours, 0.9 hours, or 1.0 hour. If the ball milling time is too long, the polycrystalline diamond will be over-crushed, resulting in excessively small particle sizes and a decreased yield. If the ball milling time is too short, the polycrystalline diamond will not be sufficiently crushed, and the crystal form will not meet the product requirements.

[0028] More preferably, the steel ball is a tungsten steel ball.

[0029] More preferably, the diameter of the steel ball is 5 to 25 mm.

[0030] More preferably, the particle size of the micro powder to be graded is 10–50 μm, the proportion of particles with an aspect ratio ≤ 1.2 is greater than or equal to 60 wt%, and the maximum aspect ratio is ≤ 1.7. If the proportion of particles with an aspect ratio ≤ 1.2 is less than 60 wt% and / or the maximum aspect ratio is greater than 1.7, then due to the large diameter difference between the micro powder particles, regardless of subsequent moisture classification, the SPAN value of the obtained polycrystalline diamond micro powder cannot be less than 0.65.

[0031] Preferably, a purification step is performed before step S3, wherein the purification step is acid boiling and / or alkali boiling to remove metallic impurities and some non-metallic impurities from the micro powder to be graded.

[0032] More preferably, the acid boiling process involves treatment with an acid solution with a pH value less than or equal to 2. Even more preferably, the acid solution used in the acid boiling process is an aqueous solution of one or more of hydrochloric acid, nitric acid, and sulfuric acid.

[0033] More preferably, the acid boiling temperature is 250℃~300℃, such as 250℃, 260℃, 270℃, 280℃, 290℃, or 300℃.

[0034] More preferably, the boiling time is 2 to 6 hours, such as 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours.

[0035] More preferably, the causticizing process involves treatment with an alkaline solution with a pH of 11-12. Even more preferably, the alkaline solution is an aqueous solution of sodium hydroxide and / or an aqueous solution of potassium hydroxide.

[0036] More preferably, the boiling temperature is 450℃~500℃, such as 450℃, 460℃, 470℃, 480℃, 490℃, or 500℃.

[0037] More preferably, the boiling time is 2 to 6 hours, such as 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours.

[0038] Preferably, in step S3, the grading is performed using an automatic micro-powder classifier via a moisture method for sedimentation grading, until the SPAN value of the polycrystalline diamond micro-powder in each batch is less than or equal to 0.65. The moisture method for sedimentation grading to achieve a SPAN value of less than or equal to 0.65 for the polycrystalline diamond micro-powder in each batch can be reasonably set and adjusted according to the morphology and structure of the micro-powder to be graded and the parameters of the specific automatic micro-powder classifier.

[0039] Preferably, the steps for classifying using an automatic micro powder classifier are as follows: When using an automatic micro powder classifier, the purified micro powder to be classified is first added to the automatic micro powder classifier, and then the slurry is stirred evenly; after stopping the rotation, sedimentation begins, and after setting the sedimentation time, the material is extracted multiple times until all the unsettled micro powder to be classified is extracted to obtain multiple batches of polycrystalline diamond micro powder; the settled micro powder to be classified is used as raw material to start the next sedimentation, until there is no more sedimentation material discharged.

[0040] Preferably, the settlement height is 280-480mm, such as 280mm, 300mm, 320mm, 340mm, 360mm, 380mm, 400mm, 420mm, 440mm, 460mm, or 480mm.

[0041] More preferably, the water method uses a sodium silicate aqueous solution with a concentration of 1-5 wt%, such as 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%.

[0042] More preferably, the settling time is 200 to 500 seconds, such as 200 seconds, 250 seconds, 300 seconds, 350 seconds, 400 seconds, or 500 seconds.

[0043] More preferably, the single extraction time is 20 to 80 seconds, such as 20 seconds, 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds, or 80 seconds.

[0044] After the grading process, multiple batches of polycrystalline diamond micropowder are formed, with varying D values ​​between each batch. 50 It exhibits a certain gradient distribution trend, with gradient differences ranging from 2 to 15 μm. For example, in this application, for D... 50 Polycrystalline diamond powder with a particle size of 10–50 μm was produced in four batches. The density (D) of each batch of powder is as follows: 50 The sizes are 10–20 μm, 20–30 μm, 30–40 μm, and 40–50 μm.

[0045] Preferably, the polycrystalline diamond micro powder obtained from the grading is dried.

[0046] A second aspect of the present invention discloses a polycrystalline diamond micro powder obtained by any of the preparation methods described above.

[0047] Preferably, the polycrystalline diamond micropowder has good self-sharpening properties. These properties are determined by the polycrystalline form of the diamond micropowder, which can be observed from the SEM image of the polycrystalline diamond micropowder.

[0048] Preferably, the polycrystalline diamond micropowder has a D... 50 The value is 10–50 μm, as described in D. 50 It can be 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, or 50μm.

[0049] Preferably, the proportion of the polycrystalline diamond micropowder with an aspect ratio ≤1.2 is at least 60 wt%, and the maximum aspect ratio is ≤1.7.

[0050] Preferably, the SPAN value of each batch of the polycrystalline diamond micro powder is ≤0.65.

[0051] The third aspect of this invention discloses the use of polycrystalline diamond micro powder as described above in the field of finishing.

[0052] Preferably, the polycrystalline diamond micropowder is used in grinding and / or polishing.

[0053] The polycrystalline diamond micro powder for grinding and polishing semiconductor devices and its preparation method described in this application have the following beneficial effects:

[0054] In this application, the applicant creatively proposes a novel method for preparing polycrystalline diamond micropowder. The prepared polycrystalline diamond micropowder exhibits good crystal structure and self-sharpening properties, making it widely applicable in grinding and semiconductor device polishing. Compared to traditional blasting methods, this method is convenient and controllable, produces micropowder with larger particle sizes, boasts high production efficiency, has low limitations on production site requirements, and is safe and reliable. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the first side of a ball mill jar for shaping diamond micropowder as described in this invention;

[0056] Figure 2 This is a schematic diagram of the second side of a ball milling jar for shaping diamond micron powder as described in this invention;

[0057] Figure 3 This is a perspective view of a ball milling jar for shaping diamond micron powder as described in this invention;

[0058] Figure 4 This is a schematic diagram of the trajectory of the steel ball moving in a ball milling jar for shaping diamond micron powder as described in this invention.

[0059] Figure 5This is a SEM image (1000x magnification) of the dried polycrystalline diamond micropowder in Example 1 of this invention.

[0060] Figure 6 This is a SEM image (1000x magnification) of the dried polycrystalline diamond micropowder in Example 2 of this invention.

[0061] Figure 7 This is a SEM image (1000x magnification) of the dried polycrystalline diamond micropowder in Example 3 of this invention.

[0062] Figure 8 This is a SEM image (500x magnification) of the dried polycrystalline diamond micropowder in Example 4 of this invention.

[0063] Figure 9 This is a SEM image (1000x magnification) of the dried polycrystalline diamond micropowder in Example 5 of this invention.

[0064] Figure 10 This is a SEM image (1000x magnification) of the dried polycrystalline diamond micropowder in Comparative Example 1 of this invention.

[0065] Explanation of icon numbers

[0066] 100 Grinding jar 200 can lid 300 First guide rod assembly 301 Guide rod 400 Second guide rod assembly 500 Third guide rod assembly 600 Fourth guide rod assembly 700 Shaft fixing component 800 pivot 900 Can lid fastener Detailed Implementation

[0067] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0068] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0069] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0070] The method for preparing polycrystalline diamond micropowder for grinding and polishing described in the specific embodiments of this application requires the use of a method such as Figures 1-3 The specific grinding jar 100 for shaping diamond micron powder is shown, and high-density, high-hardness grinding steel balls are used; the inner wall of the grinding jar 100 is provided with multiple guide rods that are perpendicular to the inner wall.

[0071] In one specific embodiment, the grinding jar is made of alloy steel, and the density of the grinding steel balls is 10–20 g / cm³. 3 Its hardness is HRC 50-100.

[0072] In this application, the applicant creatively selects high-density and high-hardness grinding steel balls and combines them with a grinding jar equipped with a guide rod for grinding. During actual grinding, the polycrystalline diamond powder rotates together with the grinding steel balls in the grinding jar and is guided by the guide rod, thereby ensuring that the grinding steel balls can exert a greater force on the polycrystalline diamond powder during grinding, thus grinding the polycrystalline diamond powder and producing more edges and corners.

[0073] In a like Figure 1 In the specific embodiment shown, the ball milling device includes a ball milling jar 100 and a jar cover 200, which are rotatably connected. The ball milling jar 100 is provided with a first guide rod assembly 300, a second guide rod assembly 400, a third guide rod assembly 500, and a fourth guide rod assembly 600. The first guide rod assembly 300 and the third guide rod assembly 500 are arranged opposite to each other, and the second guide rod assembly 400 and the fourth guide rod assembly 600 are arranged opposite to each other. Each of the first guide rod assembly 300, the second guide rod assembly 400, the third guide rod assembly 500, and the fourth guide rod assembly 600 includes a plurality of guide rods 301 spaced apart along the vertical direction of the jar wall of the ball milling jar 100.

[0074] In one specific embodiment, the guide rods 301 of the first guide rod assembly 300 and the second guide rod assembly 400, as well as the guide rods 301 of the third guide rod assembly 500 and the fourth guide rod assembly 600, are all arranged alternately.

[0075] In a more specific embodiment, the included angles of the guide rods 301 of the first guide rod assembly 300 and the second guide rod assembly 400, and the guide rods 301 of the third guide rod assembly 500 and the fourth guide rod assembly 600 are all 90 degrees.

[0076] In a more specific embodiment, the first guide rod assembly 300 and the third guide rod assembly 500 each include 4 to 8 guide rods 301; the second guide rod assembly 400 and the fourth guide rod assembly 600 each include 4 to 8 guide rods 301.

[0077] In a more specific embodiment, the lengths of the guide rods 301 of the first guide rod assembly 300 and the third guide rod assembly 500 are less than the lengths of the guide rods 301 of the second guide rod assembly 400 and the fourth guide rod assembly 600. In the implementation of this application, steel balls are loaded into the grinding jar 100. Since the guide rods 301 of the first guide rod assembly 300 and the second guide rod assembly 400, and the guide rods 301 of the third guide rod assembly 500 and the fourth guide rod assembly 600 are all staggered, as... Figure 4 As shown, a moving channel is formed between two vertically adjacent guide rods 301, which drives the steel ball to move along the grinding jar 100.

[0078] The ball mill jar with four rows of guide rods installed inside, with the four rows arranged in two groups facing each other and the groups interleaving each other, increases the frequency of tumbling and impact on the steel balls inside the jar, thereby improving the shaping efficiency and quality.

[0079] In one specific embodiment, the ball mill jar 100 is provided with a rotating shaft fixing member 700, the rotating shaft fixing member 700 is connected to the rotating shaft 800, the rotating shaft 800 is connected to the jar lid fixing member 900, and the jar lid fixing member 900 is connected to the jar lid 200, so as to facilitate the opening and closing of the jar lid 200.

[0080] To address the technical challenges of achieving both good self-sharpening properties and micron-sized particle sizes in the processing of polycrystalline diamond micropowder, the applicant developed a method using a ball mill jar and high-density, high-hardness steel balls. The ball mill jar has multiple vertical guide rods on its inner wall, and the processing parameters are controlled to achieve micron-sized polycrystalline diamond micropowder while maintaining a crystal structure with excellent self-sharpening properties. This meets the requirements for diamond tools used in grinding and polishing semiconductor devices, and achieves the desired product specifications. Compared to traditional blasting methods, this method significantly improves yield and production efficiency.

[0081] In the following specific embodiments, the specific steps include:

[0082] 1) Use a jaw crusher to break polycrystalline diamond into small pieces;

[0083] 2) Use a roller mill to crush the fragments into particles with a maximum length of 2mm;

[0084] 3) The fragmented particles are ball-milled to a maximum particle size of 50 μm;

[0085] 4) The ball-milled particles are purified by boiling in acid or alkali to remove impurities;

[0086] 5) The purified particles are finely graded to form multiple batches of polycrystalline diamond micro powder;

[0087] 6) Dry the multiple batches of polycrystalline diamond powder.

[0088] The following examples and their corresponding effect data further demonstrate and illustrate the progress of the above technical solutions and effects.

[0089] Example 1

[0090] The specific preparation method of polycrystalline diamond micropowder for grinding and polishing semiconductor devices in this embodiment includes the following steps:

[0091] 1) Provide cylindrical polycrystalline diamond as raw material with an impact toughness Ti value of 71-73, a thermal shock toughness TTi value of 65-67, a graphite basic particle size of 5-6μm, an average diameter of 30mm, and an average thickness of 10mm.

[0092] 2) The polycrystalline diamond is crushed into fragments using a jaw crusher, the output particle size of the jaw crusher is 6-10mm, and the fragments are crushed into particles using a roller mill. After the above treatment, the particle diameter is less than or equal to 2mm.

[0093] 3) The fragments are ball-milled and shaped using an alloy steel ball mill jar with a density of 13.0–14.0 g / cm³. 3 Tungsten carbide balls with a hardness of HRC 80-90 are used for ball milling. The inner wall of the ball mill jar 100 is equipped with multiple guide rods perpendicular to the inner wall. The ball milling and shaping process is performed at a rotation speed of 45 rad / s. The tungsten carbide balls are a mixture of three diameters: 20 mm, 12 mm, and 10 mm. The ratio of 20 mm, 12 mm, and 10 mm diameter tungsten carbide balls is 3:4:3. The ball-to-material ratio is 12:1, and the ball milling time is 0.5 hours. After the above ball milling and shaping process, the particle size of the micro-powder to be classified is 10-50 μm; the proportion of particles with an aspect ratio ≤1.2 is greater than or equal to 60 wt%, and the maximum aspect ratio is ≤1.7.

[0094] 4) The micro powder to be graded is purified by acid and alkali boiling. The acid boiling is carried out using aqua regia with a pH of less than or equal to 1, at a temperature of 260°C, and for 3 hours. After the acid boiling is completed, sulfuric acid and nitric acid with a pH of 1-2 are mixed at a volume ratio of 9:1 to prepare nitric acid solution, and the acid boiling temperature is 260°C for 3 hours. The alkali boiling is carried out using sodium hydroxide aqueous solution with a pH of 11-12, at a temperature of 500°C, and for 5 hours.

[0095] 5) The automatic micron powder classifier uses a 3wt% sodium silicate aqueous solution for sedimentation classification via a water method. The classification steps are as follows: First, the purified micron powder to be classified is added to the automatic micron powder classifier, and then the slurry is stirred evenly. After the rotation stops, the micron powder to be classified begins to settle, with a settling height of 480mm. The settling time is set to 500s, and the single extraction time is 70s. Multiple extractions are performed until all unsettled micron powder to be classified has been extracted. Then, the settled micron powder is used as raw material for the next settling cycle, until no more material is discharged.

[0096] 6) The polycrystalline diamond micro powder obtained from the classification is dried to obtain the final product.

[0097] After testing, the final product is:

[0098] 1) SEM image as shown Figure 5 As shown, the micronized powder is polycrystalline and possesses excellent self-sharpening properties. Scanning electron microscopy (SEM) analysis revealed that 92 wt% of the micronized powder had an aspect ratio ≤1.2, with a maximum aspect ratio of 1.36. Self-sharpening refers to the phenomenon where, after the abrasive grains become dull, the grinding force increases, causing the grains to break or detach, thus re-exposing a sharp cutting edge. Because the final product is polycrystalline, some grains detach after dulling, re-exposing sharp edges, resulting in excellent self-sharpening properties.

[0099] 2) The particle size distribution (D) of each batch of micronized powder was obtained by testing with a Mastersizer 3000 laser particle size analyzer. 50 The corresponding sizes are 13μm, 27μm, 35μm, and 44μm;

[0100] 3) The particle size distribution was obtained using a Mastersizer 3000 laser particle size analyzer. 50 The SPAN value of the 13μm batch of micronized powder was 0.619, D 50 The SPAN value of the 27μm batch of micronized powder was 0.593, D 50 The SPAN value of the 35μm batch of micronized powder was 0.611, D 50 The SPAN value of the 44μm batch of micronized powder is 0.605;

[0101] 4) Finished product yield (the ratio of qualified output to the mass of raw polycrystalline diamond): 85%.

[0102] Example 2

[0103] This embodiment provides another specific preparation method using the technical solution of this application:

[0104] 1) Provide cylindrical polycrystalline diamond with an impact toughness Ti value of 71-73, a thermal shock toughness TTi value of 65-67, a basic particle size of 5-6μm, an average diameter of 30mm, and an average thickness of 10mm as raw material.

[0105] 2) The polycrystalline diamond is crushed into fragments using a jaw crusher. The output particle size of the jaw crusher is 6-10 mm. The fragments are then crushed into particles using a roller mill. After the above treatment, the particle diameter is less than or equal to 2 mm.

[0106] 3) The fragments are ball-milled and shaped using an alloy steel ball mill jar with a density of 13.0–14.0 g / cm³. 3 Tungsten carbide balls with a hardness of HRC 80-90 are used for ball milling. The inner wall of the ball mill jar 100 is equipped with multiple guide rods perpendicular to the inner wall. The ball milling and shaping process is performed at a rotation speed of 45 rad / s. The tungsten carbide balls are a mixture of three diameters: 18 mm, 10 mm, and 8 mm. The ratio of 18 mm, 10 mm, and 8 mm diameter tungsten carbide balls is 3:4:3. The ball-to-material ratio is 12:1, and the ball milling time is 0.5 hours. After the above ball milling and shaping process, the particle size of the micro-powder to be classified is 10-50 μm; the proportion of particles with an aspect ratio ≤1.2 is greater than or equal to 60 wt%, and the maximum aspect ratio is ≤1.7.

[0107] 4) The micro-powder to be graded is purified by acid and alkali boiling; the acid boiling uses aqua regia with a pH of less than or equal to 1, the boiling temperature is 260℃, and the boiling time is 3 hours; after the boiling, sulfuric acid and nitric acid with a pH of 1-2 are mixed at a volume ratio of 9:1 to prepare nitric acid, the boiling temperature is 260℃, and the boiling time is 3 hours; the alkali boiling uses a solution with a pH of...

[0108] 11-12 were treated with sodium hydroxide aqueous solution, the boiling temperature was 500℃, and the boiling time was 5h;

[0109] 5) An automatic micron powder classifier is used, employing a 3wt% sodium silicate aqueous solution for sedimentation classification via a water method. The classification steps are as follows: First, the purified micron powder to be classified is added to the automatic micron powder classifier, and then the slurry is stirred evenly. After the rotation stops, the micron powder to be classified begins to settle, with a settling height of 480mm. The settling time is set to 500s, and the single extraction time is 70s. Multiple extractions are performed until all unsettled micron powder to be classified is extracted to obtain D. 50 The microcrystalline diamond powders are 16μm, 24μm, 32μm, and 47μm respectively; the settled microcrystalline powders to be classified are used as raw materials to start the next settling process until there is no more settling material.

[0110] 6) The polycrystalline diamond micro powder obtained from the classification is dried to obtain the final product.

[0111] After testing, the final product is:

[0112] 1) SEM image as shown Figure 6 As shown, the micro powder is polycrystalline and has good self-sharpening properties; according to scanning electron microscopy, the proportion of micro powder with an aspect ratio ≤1.2 reached 81 wt%, and the maximum aspect ratio was 1.52.

[0113] 2) The particle size distribution (D) of each batch of micronized powder was obtained by testing with a Mastersizer 3000 laser particle size analyzer. 50 The corresponding sizes are 16μm, 24μm, 32μm, and 47μm;

[0114] 3) The particle size distribution was obtained using a Mastersizer 3000 laser particle size analyzer. 50 The SPAN value of the 16μm batch of micronized powder is 0.630, D 50 The SPAN value of the 24μm batch of micronized powder is 0.624, D 50 The SPAN value of the 32μm batch of micronized powder was 0.633, D 50 The SPAN value of the 47μm batch of micronized powder is 0.645;

[0115] 4) Finished product yield (the ratio of qualified output to the mass of raw polycrystalline diamond): 66%.

[0116] Example 3

[0117] This embodiment provides another specific preparation method using the technical solution of this application, which differs from Embodiment 1 in that the ratio of the amount of tungsten steel balls with a diameter of 20 mm, tungsten steel balls with a diameter of 12 mm, and tungsten steel balls with a diameter of 10 mm is 2:3:2.

[0118] After testing, the final product is:

[0119] 1) SEM image as shown Figure 7 As shown, the micro powder is polycrystalline and has good self-sharpening properties; according to scanning electron microscopy, the proportion of micro powder with an aspect ratio ≤1.2 reached 85wt%, and the maximum aspect ratio was 1.41.

[0120] 2) The particle size distribution (D) of each batch of micronized powder was obtained by testing with a Mastersizer 3000 laser particle size analyzer. 50 The corresponding sizes are 11μm, 23μm, 36μm, and 42μm;

[0121] 3) The particle size distribution was obtained using a Mastersizer 3000 laser particle size analyzer. 50 The SPAN value of the 11μm batch of micronized powder is 0.617, D 50 The SPAN value of the 23μm batch of micronized powder was 0.612, D 50 The SPAN value of the 36μm batch of micronized powder was 0.608, D 50 The SPAN value of the 42μm batch of micronized powder was 0.623;

[0122] 4) Finished product yield (ratio of qualified output to raw polycrystalline diamond): 74%.

[0123] Example 4

[0124] This embodiment provides another specific preparation method using the technical solution of this application, which differs from Example 2 in that: a density of 11.0–12.0 g / cm³ is used. 3 Tungsten carbide balls with a hardness of HRC 60-70 were used for ball milling.

[0125] After testing, the final product is:

[0126] 1) SEM image as shown Figure 8 As shown, the micro powder is polycrystalline and has good self-sharpening properties; according to scanning electron microscopy, the proportion of micro powder with an aspect ratio ≤1.2 reached 78 wt%, and the maximum aspect ratio was 1.60.

[0127] 2) The particle size distribution (D) of each batch of micronized powder was obtained by testing with a Mastersizer 3000 laser particle size analyzer. 50 The corresponding sizes are 18μm, 27μm, 38μm, and 46μm;

[0128] 3) The particle size distribution was obtained using a Mastersizer 3000 laser particle size analyzer. 50 The SPAN value of the 18μm batch of micronized powder was 0.633, D 50 The SPAN value of the 27μm batch of micronized powder was 0.648, D 50 The SPAN value of the 38μm batch of micronized powder was 0.641, D50 The SPAN value of the 46μm batch of micronized powder was 0.638;

[0129] 4) Finished product yield (the ratio of qualified output to the mass of raw polycrystalline diamond): 68%.

[0130] Example 5

[0131] This embodiment provides another specific preparation method using the technical solution of this application, which differs from Embodiment 1 in that the ball milling time is 1 hour.

[0132] After testing, the final product is:

[0133] 1) SEM image as shown Figure 9 As shown, the micro powder is polycrystalline and has good self-sharpening properties; according to scanning electron microscopy, the proportion of micro powder with an aspect ratio ≤1.2 reached 88 wt%, and the maximum aspect ratio was 1.56.

[0134] 2) The particle size distribution (D) of each batch of micronized powder was obtained by testing with a Mastersizer 3000 laser particle size analyzer. 50 The corresponding sizes are 11μm, 22μm, 31μm, and 43μm;

[0135] 3) The particle size distribution was obtained using a Mastersizer 3000 laser particle size analyzer. 50 The SPAN value of the 11μm batch of micronized powder is 0.568, D 50 The SPAN value of the 22μm batch of micronized powder was 0.588, D 50 The SPAN value of the 31μm batch of micronized powder was 0.581, D 50 The SPAN value of the 43μm batch of micronized powder was 0.573;

[0136] 4) Finished product yield (ratio of qualified output to polycrystalline diamond): 82%.

[0137] Comparative Example 1

[0138] The specific preparation method of the polycrystalline diamond micropowder used for grinding and polishing semiconductor devices in this comparative example includes the following steps:

[0139] 1) Provide cylindrical polycrystalline diamond with an impact toughness Ti value of 71-73, a thermal shock toughness TTi value of 65-67, a basic particle size of 5-6μm, an average diameter of 30mm, and an average thickness of 10mm as raw material.

[0140] 2) The polycrystalline diamond is crushed into fragments using a jaw crusher, the output particle size of the jaw crusher is 6-10mm, and the fragments are crushed into particles using a roller mill. After the above treatment, the particle diameter is less than or equal to 2mm.

[0141] 3) The fragments are ball-milled and shaped using an alloy steel ball mill jar with a density of 7.8–8.0 g / cm³. 3 Ordinary steel balls with a hardness of HRC 55 are used for ball milling. The inner wall of the ball mill jar 100 is equipped with multiple guide rods perpendicular to the inner wall. The ball milling and shaping process is carried out at a rotation speed of 45 rad / s. The ordinary steel balls used are a mixture of three diameters: 20 mm, 12 mm, and 10 mm. The ratio of ordinary steel balls with diameters of 20 mm, 12 mm, and 10 mm is 3:4:3. The ball-to-material ratio is 12:1, and the ball milling time is 0.5 hours.

[0142] 4) The pulverized powder to be graded is purified by acid and alkali boiling. The acid boiling is performed using aqua regia with a pH of less than or equal to 1, at a temperature of 260°C, for 3 hours. After the acid boiling, sulfuric acid and nitric acid with a pH of 1-2 are mixed at a volume ratio of 9:1 to prepare nitric acid solution, and the acid boiling temperature is 260°C for 3 hours. The alkali boiling is performed using a sodium hydroxide aqueous solution with a pH of 11-12, at a temperature of 500°C, for 5 hours.

[0143] 5) The automatic micron powder classifier uses a 3wt% sodium silicate aqueous solution for sedimentation classification via a water method. The classification steps are as follows: First, the purified micron powder to be classified is added to the automatic micron powder classifier, and then the slurry is stirred evenly. After the rotation stops, the micron powder to be classified begins to settle, with a settling height of 480mm. The settling time is set to 500s, and the single extraction time is 70s. Multiple extractions are performed until all unsettled micron powder to be classified is extracted, yielding polycrystalline diamond micron powder with D50 values ​​of 22μm, 35μm, 47μm, and 56μm.

[0144] The settled micro-powder to be classified is used as raw material to start the next settling process until there is no more settling material discharged.

[0145] 6) The polycrystalline diamond micro powder obtained from the classification is dried to obtain the final product.

[0146] After testing, the final product is:

[0147] 1) SEM image as shown Figure 10 As shown, according to scanning electron microscopy, the proportion of micropowder with an aspect ratio ≤ 1.2 reached 18 wt%, and the maximum aspect ratio was 1.94;

[0148] 2) The D50 values ​​of the micronized powders from each batch were 22 μm and 35 μm, respectively, as measured by a Mastersizer 3000 laser particle size analyzer.

[0149] μm, 47μm, 56μm;

[0150] 3) The SPAN value of the micro powder with a D50 of 22μm was obtained by testing with a Mastersizer 3000 laser particle size analyzer. The SPAN value of the micro powder with a D50 of 22μm was 0.845, the SPAN value of the micro powder with a D50 of 35μm was 0.838, the SPAN value of the micro powder with a D50 of 47μm was 0.857, and the SPAN value of the micro powder with a D50 of 56μm was 0.870.

[0151] 4) Finished product yield (the ratio of qualified output to the mass of raw polycrystalline diamond): 0%.

[0152] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0153] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing polycrystalline diamond micropowder for grinding and polishing, characterized in that, Includes the following steps: S1. Provide polycrystalline diamond as raw material; S2. The polycrystalline diamond is crushed to form micro powder to be graded; S3. The micro powder to be graded is used to form multiple batches of polycrystalline diamond micro powder; The polycrystalline diamond is formed by sintering 5-6 μm graphite particles with a binder; the diameter of the polycrystalline diamond is 20-40 mm; the height of the polycrystalline diamond is 5-15 mm; in step S3, the grading is performed using an automatic micro-powder classifier with a moisture content method for sedimentation grading, and finally, the material is extracted in batches to obtain D. 50 It is a polycrystalline diamond powder with a size of 10~50μm, and the SPAN value of each batch is less than or equal to 0.65; In step S2, the pulverization process includes the following steps: 1) crushing the polycrystalline diamond into fragments using a jaw crusher; 2) pulverizing the fragments into particles using a roller mill; 3) ball milling the particles to form micro powder to be graded. The ball milling shaping process uses a ball mill jar and a density of 13~14 g / cm³. 3 Tungsten steel balls with a hardness of HRC 80~90 are used for ball milling, and the inner wall of the ball milling jar is provided with multiple guide rods perpendicular to the inner wall. The water method uses a sodium silicate aqueous solution with a concentration of 1~5wt%; In S1, the impact toughness Ti value of the polycrystalline diamond is 65~75, and the thermal shock toughness TTi value is 60~70. The tungsten carbide balls are a mixture of three types with diameters of 15-25 mm, 11-14 mm, and 6-10 mm, and the ratio of tungsten carbide balls with diameters of 15-25 mm, 11-14 mm, and 6-10 mm is (0.1-1):1:(0.1-1). The proportion of the polycrystalline diamond micropowder with an aspect ratio ≤ 1.2 is greater than or equal to 60 wt%, and the maximum aspect ratio is ≤ 1.

7.

2. The preparation method according to claim 1, characterized in that, In S1, the polycrystalline diamond is cylindrical; And / or, the preparation method further includes a purification step before step S3, wherein the purification is performed by boiling in acid and / or boiling in alkali.

3. The preparation method according to claim 1, characterized in that, The discharge particle size of the jaw crusher is 6~10mm; And / or, the diameter of the fragments is less than or equal to 2 mm; And / or, the ball milling shaping process takes 0.2 to 1 hour; and / or, the ball mill jar rotates at a speed of 40 to 60 rad / s; And / or, the particle size of the powder to be graded is less than or equal to 50 μm.

4. The preparation method according to claim 3, characterized in that, The grinding jar is made of alloy steel; And / or, the ball-to-material ratio of the ball milling shaping process is (8~10):

1.

5. The preparation method according to claim 2, characterized in that, The acid boiling process involves treating the affected area with an acid solution having a pH value less than or equal to 2. And / or, the temperature for boiling the acid is 250℃~300℃; And / or, the acid boiling time is 2-6 hours; And / or, the caustic soda boiling is performed using an alkaline solution with a pH of 11-12; And / or, the temperature of the caustic soda boiling is 450℃~500℃; And / or, the boiling time is 2-6 hours; And / or, the acid solution in the boiling acid is an aqueous solution of one or more of hydrochloric acid, nitric acid and sulfuric acid; And / or, the alkaline solution is an aqueous solution of sodium hydroxide and / or an aqueous solution of potassium hydroxide; And / or, the settling time in the moisture method is 200~500s; And / or, the single extraction time of the material in the moisture method is 20~80s; And / or, the settling height in the moisture method is 280~480mm; And / or, dry the polycrystalline diamond micron powder obtained after the grading.

6. A polycrystalline diamond micron powder obtained by the preparation method according to any one of claims 1 to 5.

7. The polycrystalline diamond micron powder according to claim 6, characterized in that, The polycrystalline diamond micro powder has good self-sharpening properties.

8. The use of the polycrystalline diamond micron powder as described in claim 7 in grinding and polishing.

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