Semiconductor package grinding wheel and method of manufacturing the same

Abstract

The application provides a kind of grinding wheel for semiconductor package grinding and its preparation method, which is applied to the grinding and grinding processing of semiconductor product package post-processing, the grinding wheel includes abrasive layer and matrix;The end surface of the matrix is uniformly distributed with several circular pills in the circumferential direction, the circular pills constitute the abrasive layer, and the abrasive layer includes the following components: diamond, ordinary abrasive, lubricant, reinforcing fiber, modified resin powder;The diamond is single crystal multi-fluted, and the diamond particle size is 400-8000#. The grinding wheel prepared by the application presents a high brittleness low hardness self-lubricating state, which is beneficial to cope with the intermittent structure of hard phase and soft phase of semiconductor package module material, the complex grinding scene with large material characteristic span, effectively solves the problems of poor self-sharpening of traditional grinding wheel, easy to burn workpiece, low machining precision, poor impact resistance of grinding wheel, low life and the like.

Description

Technical Field

[0001] This invention relates to the field of grinding wheel preparation, and more specifically to a grinding wheel for semiconductor packaging and its preparation method. Background Technology

[0002] The semiconductor industry is characterized by its large scale, numerous sub-sectors, and rapid technological advancements. However, insufficient investment in basic research and product development in my country has hindered breakthroughs in key technologies and equipment such as chip design and manufacturing. Grinding and polishing are post-packaging processes that directly impact the final performance and overall yield of the module. Poor grinding results can lead to significant economic losses. Currently, high-end grinding equipment and products in the semiconductor industry are mainly concentrated in countries such as the United States, Japan, and South Korea. With the rapid development of the semiconductor industry, semiconductor devices are becoming smaller and the materials more diverse, placing increasingly higher demands on the flatness of semiconductor wafers and module surfaces. Therefore, developing grinding and polishing tools and consumables for the semiconductor industry, as well as domestic alternatives, is imperative.

[0003] In semiconductor packaging, grinding wheels need to handle complex material environments, including easily burned resin materials (such as epoxy resin and silicone), hard resin fillers (such as alumina and glass fiber), and metal materials that easily adhere to material surfaces (such as pure copper). Therefore, semiconductor packaging materials consist of alternating hard and soft phases, with a wide range of material properties, placing higher demands on the performance of grinding wheels. Currently used conventional resin grinding wheels have many problems, such as easy chip formation, easy deep scratches on workpiece surfaces, and a high wear rate (10%–20%). Furthermore, these wheels are difficult to dress, and the lubricants used in traditional grinding wheels are generally materials such as graphite and molybdenum disulfide, which have weak lubrication capabilities and require large amounts to achieve a lubricating effect. However, excessive addition can significantly reduce the overall strength of the grinding wheel, causing excessive wear.

[0004] Therefore, there is an urgent need to develop a new type of grinding wheel suitable for semiconductor packaging grinding to meet market demand. Summary of the Invention

[0005] To address the numerous problems associated with conventional resin grinding wheels, a grinding wheel for semiconductor packaging and its preparation method are provided. This grinding wheel can effectively perform grinding operations on semiconductor packaging materials with a large range of discontinuous material properties between the hard and soft phases, achieving excellent processing results. The specific solution is as follows:

[0006] A grinding wheel for semiconductor packaging is used in grinding and polishing processes after semiconductor product packaging. The grinding wheel includes an abrasive layer and a substrate. A plurality of circular pellets are evenly distributed circumferentially on the end face of the substrate, and these circular pellets constitute the abrasive layer. The abrasive layer comprises the following components in parts by weight:

[0007] diamond 15-35 parts;

[0008] ordinary abrasive 5-25 parts;

[0009] lubricant 5-15 parts;

[0010] reinforcing fiber 10-20 parts;

[0011] modified resin powder 35-55 parts;

[0012] The diamond is single crystal multi-edge, and the diamond particle size is 400-8000#.

[0013] The base end face is provided with a plurality of circular pills which are uniformly distributed in the circumferential direction, which can facilitate the discharge of grinding fluid and the chip containing effect, reduce the grinding resistance in the grinding process of the grinding wheel, and thus indirectly improve the grinding sharpness and avoid scratching.

[0014] Further, the ordinary abrasive is one or a combination of several of silicon carbide, corundum, aluminum oxide or chromium oxide; the lubricant is a blend of graphite or molybdenum disulfide and chromium aluminum carbide; the reinforcing fiber is one or a combination of several of glass fiber, carbon fiber, aluminum oxide fiber; the modified resin powder is a blend of modified phenolic resin powder or cyan resin powder with organic silicon, rubber, polyurethane, polyvinyl butyral ester, epoxy resin powder.

[0015] Further, the silicon carbide is polycrystalline green silicon carbide, the corundum is microcrystalline white corundum, the particle size of the aluminum oxide and the chromium oxide is 200-6000#; the particle size of the graphite and the molybdenum disulfide is one particle size number lower than that of the diamond, and the particle size of the chromium aluminum carbide is one particle size number coarser than that of the diamond.

[0016] Further, the aspect ratio of the reinforcing fiber is not higher than 15, and the diameter is less than 30μm.

[0017] Further, the mixing machine or the twin-screw extruder is used for blending modification, the temperature of the 1-9 sections of the twin-screw extruder is set to 80℃, 120℃, 160℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃, and 180℃, respectively, and the screw rotation speed is set to 100-150r / min.

[0018] Further, the particle size of the modified resin powder is 20-100μm, and the ratio of the modified resin powder to the phenolic resin powder or the cyan resin powder is 1:1-1:4.

[0019] A preparation method of a grinding wheel for grinding a semiconductor package, comprising the following steps:

[0020] S1: according to the components of the abrasive layer, the diamond, common abrasive, lubricant and reinforcing fiber in the formula are poured into an acetone or alcohol solution, stirred uniformly, centrifuged and ultrasonically treated for not less than 20 min, dried, and a mixed material A is obtained;

[0021] S2: the modified resin powder is crushed, ball milled, dried, and sieved, and a mixed material B is obtained;

[0022] S3: the mixed material A and the mixed material B are uniformly mixed, and a mixed material C is obtained;

[0023] S4: the mixed material C is placed into a mold, and is kept at a temperature of 120-160 DEG C and a pressure of 1-6 MPa for 20-60 min, and after demolding, treatment can be performed.

[0024] Further, in S1, the centrifugation and ultrasonic treatment time is 40-60 min, the drying temperature is 120-140 DEG C, and after drying, the mixed material is sieved through a 100-200# sieve.

[0025] Further, in S2, low temperature is used for crushing and ball milling to ensure the performance of the resin, and the resin powder is sieved through a 100-200# sieve to ensure the particle size of the resin powder.

[0026] Further, in S3, a three-dimensional mixer is used for mixing, and the mixing time is 40-60 min, and after mixing, the mixed material is sieved through a 100-200# sieve.

[0027] Beneficial effects:

[0028] The application provides a grinding wheel for semiconductor packaging and a preparation method thereof, and specifically comprises the following advantages.

[0029] (1) The plurality of circular pills on the end surface of the grinding wheel body are uniformly distributed in the circumferential direction, which is different from the annular distribution of the traditional grinding wheel, so that the grinding fluid can be conveniently discharged and the chip can be accommodated, the grinding resistance in the grinding process of the grinding wheel is reduced, and the grinding sharpness is indirectly improved and scratching is avoided; the diamond abrasive adopted has a single-crystal multi-edge shape, which is different from the traditional diamond, is beneficial to dispersing the grinding heat and grinding stress, improves the sharpness of the grinding wheel, effectively reduces the grinding burn of the packaging material, improves the grinding consistency, and improves the surface processing quality.

[0030] (2) The abrasive adopted in the application is polycrystalline green silicon carbide, microcrystalline white corundum, alumina and chromium oxide, which plays a role of abrasive during grinding and also serves as a brittle particle filler, promotes brittle fracture during grinding, increases the continuous self-sharpening of the grinding wheel during grinding, plays a copper-repellent role, further improves the sharpness of the grinding wheel, and avoids the brittleness deficiency of the traditional grinding wheel and the grinding burn of the workpiece.

[0031] (3) The modified resin powder and physical modification method used in this invention are beneficial to forming a low-hardness tough material with a flexible chain structure without damaging its brittle fracture performance; unlike chemical modification methods, it avoids the problem of a serious decrease in brittle fracture performance.

[0032] (4) The present invention uses a blend of graphite, molybdenum disulfide and aluminum chromium carbide. A small amount of the blend is sufficient to meet the lubrication performance, without affecting the overall strength of the grinding wheel, and can effectively prevent workpiece surface burns.

[0033] (5) Traditional resin-reinforced grinding wheels have a high wear ratio and rapid wheel profile changes, resulting in uneven grinding surface texture, low dimensional accuracy, and reduced product yield. The addition of fiber-reinforced materials can effectively improve the impact resistance of the grinding wheel, prevent the grinding wheel from being worn out rapidly due to severe vibration under high-speed grinding conditions, thereby affecting the workpiece's machining dimensions and improving product consistency.

[0034] In summary, the grinding wheel prepared by this invention has a Rockwell hardness of HRF (30-40) and an elastic modulus of (0.005-0.030)*10⁻⁶. 5 MPa, exhibiting a high brittleness, low hardness, and self-lubricating state, is beneficial for dealing with the discontinuous structure of hard and soft phases in semiconductor packaging module materials and complex grinding scenarios with large ranges in material properties. It effectively solves problems such as poor self-sharpening properties of traditional grinding wheels, easy workpiece burning, low machining accuracy, poor impact resistance of grinding wheels, and short lifespan. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of a grinding wheel used for semiconductor packaging.

[0036] Figure 2 This is a SEM image of the grinding wheel prepared in the example.

[0037] Figure 3 SEM image of foam diamond in the embodiment.

[0038] Figure 4 This is a SEM image of the reinforcing fibers in the embodiment. Detailed Implementation

[0039] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0040] Figure 1 This is a schematic diagram of the structure of a grinding wheel used for semiconductor packaging. Figure 2 Here is a SEM image of the grinding wheel prepared in the example; Figure 3 SEM images of foamed diamond in the embodiments; Figure 4SEM image of the reinforcing fiber in the embodiment.

[0041] As shown in Figure 1 The grinding wheel comprises an abrasive layer and a base; the end face of the base is uniformly distributed with a plurality of circular tablets in the circumferential direction, and the circular tablets constitute the abrasive layer. The specific implementation is as follows:

[0042] Embodiment 1

[0043] The grinding wheel of the embodiment comprises the following raw materials in parts by weight: foamed diamond (800#) 19 parts, polycrystalline green silicon carbide (1000#) 15 parts, graphite (1000#) 2 parts, chromium aluminum carbide (600#) 4 parts, carbon fiber (5-10um) 10 parts, thermoplastic polyurethane powder (15-55um) 25 parts, and phenolic resin powder (80-100um) 25 parts.

[0044] The preparation steps of the above grinding wheel are as follows:

[0045] (1) Pour the foamed diamond, polycrystalline green silicon carbide, graphite, chromium aluminum carbide, and carbon fiber in the formula into an acetone or alcohol solution and stir uniformly, centrifuge and ultrasonic for 60 min, and dry at 140℃ to obtain a mixture A;

[0046] (2) Extrude and granulate the thermoplastic polyurethane powder and the phenolic resin powder using a twin-screw extruder, and set the temperatures of the 1-9 sections of the twin-screw extruder to 80, 120, 160, 180, 180, 180, 180, 180, and 180℃, respectively; set the screw rotation speed to 150r / min; crush the modified resin powder using liquid nitrogen, ball mill, dry at 120℃, and pass through a 150# sieve to obtain a mixture B;

[0047] (3) Airflow mix the mixture A and the mixture B at an air flow rate of 4 / s for 20 min to obtain a mixture C;

[0048] (4) Place the mixture C into a mold, and keep the temperature at 140℃ and the pressure at 6MPa for 40 min to obtain a circular tablet.

[0049] (5) Perform the grinding wheel product through the conventional sandblasting, bonding, rough turning, fine turning, and fine grinding processes.

[0050] The processing parameters and effects of the grinding wheel of the embodiment are shown in Table 1.

[0051]

[0052] Table 1

[0053] Embodiment 2

[0054] The grinding abrasive wheel of the embodiment comprises the following raw materials by weight: foamed diamond (1200#) 25 parts, microcrystalline white corundum (2000#) 15 parts, molybdenum disulfide (2000#) 2 parts, chromium aluminum carbide (1000#) 4 parts, carbon fiber (5-10 um) 10 parts, polyvinyl butyral (20-45 um) 10 parts, epoxy resin powder (30-60 um) 6 parts, and phenolic resin powder (80-100 um) 19 parts.

[0055] The preparation steps of the above abrasive wheel are as follows:

[0056] (1) The diamond, polycrystalline white corundum, molybdenum disulfide, chromium aluminum carbide, and carbon fiber in the formula are poured into an acetone or alcohol solution and stirred uniformly, centrifuged and ultrasonically treated for 60 min, and dried at 140°C to obtain a mixture A;

[0057] (2) The polyvinyl butyral, epoxy resin powder, and phenolic resin powder are extruded and granulated by a twin-screw extruder, the temperature of the 1-9 sections of the twin-screw extruder is set to 60, 120, 140, 160, 160, 160, 160, 160, and 160°C, respectively, the screw rotation speed is set to 200 r / min, the modified resin powder is crushed by liquid nitrogen, ball milled, dried at 100°C, and sieved through a 200# sieve to obtain a mixture B;

[0058] (3) The mixture A and the mixture B are mixed by airflow at an air flow rate of 5 / s for 30 min to obtain a mixture C;

[0059] (4) The mixture C is placed in a mold and kept at a pressure of 8 MPa and a temperature of 130°C for 50 min to obtain a round pellet.

[0060] (5) The round pellet is subjected to the processes of conventional sand blasting, bonding, rough turning, fine turning, and fine grinding to obtain the abrasive wheel product.

[0061] The abrasive wheel of the embodiment is used for grinding semiconductor packaging materials, the processing parameters and effects are shown in Table 2.

[0062]

[0063] Table 2

[0064] Embodiment 3:

[0065] The grinding abrasive wheel of the embodiment comprises the following raw materials by weight: foamed diamond (3000#) 20 parts, microcrystalline white corundum (4000#) 15 parts, molybdenum disulfide (4000#) 2 parts, chromium aluminum carbide (3000#) 4 parts, carbon fiber (5-10 um) 5 parts, alumina fiber (4-8 um) 5 parts, silicone powder (2-4 um) 15 parts, and cyan-based resin powder (80-100 um) 25 parts.

[0066] The preparation steps of the above grinding wheel are as follows:

[0067] (1) The diamonds, polycrystalline white corundum, molybdenum disulfide, chromium aluminum carbide, carbon fibers, and aluminum oxide fibers in the formula are poured into an acetone or alcohol solution, stirred uniformly, centrifuged and ultrasonically treated for 60 min, and dried at 140℃ to obtain a mixture A;

[0068] (2) The silicone powder and the cyan-based resin powder are extruded and granulated by a twin-screw extruder, the temperatures of the 1-9 sections of the twin-screw extruder are set to 60, 120, 140, 170, 170, 170, 170, 170, and 170℃ in sequence, the screw rotation speed is set to 250 r / min, the modified resin powder is broken by liquid nitrogen, dried at 120℃, and sieved through a 200# sieve to obtain a mixture B;

[0069] (3) The mixture A and the mixture B are mixed by airflow at an air flow rate of 6 / s for 40 min to obtain a mixture C;

[0070] (4) The mixture C is placed into a mold, and is kept at a pressure of 10 MPa and a temperature of 130℃ for 60 min to obtain a round pellet.

[0071] (5) The round pellet is subjected to conventional sandblasting, bonding, rough turning, fine turning, and fine grinding processes to obtain a grinding wheel product.

[0072] The grinding wheel of the embodiment is used to grind a semiconductor packaging material on a vertical grinding machine, and the processing parameters and effects are shown in Table 3.

[0073]

[0074] Table 3

[0075] Comparative Example 1:

[0076] A conventional grinding wheel structure is used, the abrasive layer has the same ratio as in Example 1, the mixing method is the same as in Example 1, and the same processing parameters are used to process a semiconductor packaging material.

[0077] Comparative Example 2:

[0078] In Comparative Example 2, the end face of the round pellet is uniformly distributed along the circumference, the abrasive layer has the same ratio as in Example 1, 25 parts of thermoplastic polyurethane and phenolic resin powder are mixed by a conventional three-dimensional mixer, and the remaining mixing method and abrasive treatment method are the same as in Example 1.

[0079] Comparative Example 3:

[0080] The base structure of Comparative Example 3 adopts end face circular pellets which are evenly distributed in the circumferential direction, and the abrasive layer has the same ratio as that of Example 1, wherein 25 parts of thermoplastic polyurethane is replaced by phenolic resin powder, and the remaining preparation method is the same as that of Example 1.

[0081] Item Number of processed disks Roughness / um Scratch rate / % Grinding mark rate / % Example 1 620 0.187 0 <0.1 Comparative Example 1 600 0.525 15.1 53 Comparative Example 2 408 0.335 20.5 30 Comparative Example 3 355 0.335 22.3 25

[0082] The above results show that the even distribution of the base structure of the end face circular pellets in the circumferential direction is beneficial to improve the surface quality of the grinding wheel, reduce the occurrence of scratches and grinding marks.

[0083] The thermoplastic phenolic resin modified phenolic resin and the method of uniformly mixing the material by the twin-screw extruder are beneficial to the uniformity of the mixed material, and have beneficial effects on improving the service life of the grinding wheel, improving the surface quality of the grinding wheel, and reducing the occurrence of scratches and grinding marks.

[0084] Comparative Example 4:

[0085] Comparative Example 4 has the same base structure, mold layer ratio, and mixing method as Example 2, wherein the common single crystal diamond is replaced by the common single crystal diamond, the particle size is unchanged, and the processing technology is the same as that of Example 2.

[0086] Comparative Example 5:

[0087] Comparative Example 5 has the same base structure, mold layer ratio, and mixing method as Example 2, wherein the common single crystal diamond is replaced by the common single crystal diamond, the particle size is unchanged, and the processing technology is the same as that of Example 2.

[0088] Item Number of processed disks Roughness / um Scratch rate / % Grinding mark rate / % Example 2 700 0.139 0 <0.1 Comparative Example 4 700 0.325 12.7 20 Comparative Example 5 700 0.435 27.3 30

[0089] The above results show that the use of foam diamond and microcrystalline corundum has beneficial effects on improving the roughness of the grinding wheel and reducing the occurrence of scratch rate and grinding mark rate.

[0090] Comparative Example 6:

[0091] Comparative Example 6 has the same base structure, mold layer ratio, and mixing method as Example 3, wherein 4 parts of chromium aluminum carbide are replaced by molybdenum disulfide, and the processing technology is the same as that of Example 3.

[0092] Comparative Example 7:

[0093] Comparative Example 7 has the same base structure, mold layer ratio, and mixing method as Example 3, wherein 5 parts of carbon fiber are removed, the density of the grinding wheel is unchanged, and the processing technology is the same as that of Example 3.

[0094] Comparative Example 8:

[0095] Comparative Example 8 has the same base structure, mold layer ratio, and mixing method as Example 3, wherein 5 parts of carbon fiber and 5 parts of aluminum oxide fiber are removed, the density of the grinding wheel is unchanged, and the processing technology is the same as that of Example 3.

[0096] Item Number of processed disks Roughness / um Scratch rate / % Grinding mark rate / % Example 3 750 0.023 0 <0.1 Comparative Example 6 750 0.023 5.3 7.5 Comparative Example 7 550 0.023 2.9 5.7 Comparative Example 8 325 0.023 3.2 6

[0097] The above results show that the addition of chromium aluminum oxide is beneficial to reduce the scratch and grinding mark rate, because it has a relatively dense layer, has good oxidation resistance and self-lubricating performance under a small addition ratio, and can significantly reduce the friction coefficient and friction and wear of the binder.

[0098] The addition of fibers greatly improves the shape retention and service life of the grinding wheel, can improve the impact resistance of the grinding wheel, and reduce the uneven grinding lines caused by the excessive consumption of the grinding wheel profile, thereby causing the occurrence of scratches and grinding marks.

[0099] The above examples and comparative examples are only to show that the base end face circular tablets are uniformly distributed in the circumferential direction, the double screw extruder uniformly mixes the materials, the soft elastic resin modifies the phenolic resin, and the like; the foam diamond, microcrystalline corundum, chromium aluminum oxide, fibers and other raw materials all have beneficial effects on grinding semiconductor packaging materials, improving the surface quality, and reducing the occurrence of grinding marks and scratches, and the abrasive layer ratio of the present application includes but is not limited to the above.

[0100] As a further improvement, the above is only a preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A grinding wheel for semiconductor packaging, characterized in that, A grinding and polishing process used in the post-packaging treatment of semiconductor products, the grinding wheel includes an abrasive layer and a substrate; the end face of the substrate has a plurality of circular pellets evenly distributed circumferentially, the circular pellets constituting the abrasive layer, the abrasive layer comprising the following components in parts by weight: 15-35 parts diamond; 5-25 parts of ordinary abrasive; 5-15 parts lubricant; 10-20 parts of reinforcing fiber; 35-55 parts of modified resin powder; The diamond is a single crystal with multiple cutting edges, and the diamond grain size is 400~8000#. The common abrasive is one or a combination of silicon carbide, corundum, alumina, or chromium oxide; the lubricant is a blend of graphite or molybdenum disulfide and chromium aluminum carbide; the reinforcing fiber is one or a combination of glass fiber, carbon fiber, and alumina fiber; and the modified resin powder is a blend of organosilicon, rubber, polyurethane, polyvinyl butyral, epoxy resin powder, modified phenolic resin powder, or cyano resin powder. The silicon carbide is polycrystalline green silicon carbide, the corundum is microcrystalline white corundum, and the alumina and chromium oxide have a particle size of 200-6000#. The particle size of graphite and molybdenum disulfide is one particle size smaller than that of diamond, and the particle size of chromium aluminum carbide is one particle size coarser than that of diamond.

2. The grinding wheel for semiconductor packaging according to claim 1, characterized in that, The aspect ratio of the reinforcing fiber is not higher than 15, and the diameter is less than 30μm.

3. The grinding wheel for semiconductor packaging according to claim 1, characterized in that, During the blending modification, the mixture is passed through a mixer or a twin-screw extruder. The temperatures of sections 1 to 9 of the twin-screw extruder are set to 80℃, 120℃, 160℃, 180℃, 180℃, 180℃, 180℃, 180℃, and 180℃ respectively. The screw speed is set to 100-150 r / min.

4. A method for preparing a grinding wheel for semiconductor packaging as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1: According to the composition of the abrasive layer, pour the diamond, ordinary abrasive, lubricant and reinforcing fiber in the formula into acetone or alcohol solution, stir evenly, centrifuge and sonicate for no less than 20 minutes, dry, and obtain mixture A. S2: Crush the modified resin powder, ball mill it, dry it, and sieve it to obtain mixture B; S3: Mix mixture A and mixture B evenly to obtain mixture C; S4: Place the mixture C into the mold and keep it under pressure of 1-6MPa and temperature of 120-160℃ for 20-60 minutes. After demolding, it can be processed.

5. The method for preparing a grinding wheel for semiconductor packaging according to claim 4, characterized in that, Centrifugation and ultrasonication in S1 for 40-60 minutes, drying temperature 120-140℃, and then passing through a 100-200# sieve.

6. The method for preparing a grinding wheel for semiconductor packaging according to claim 4, characterized in that, S2 uses low-temperature crushing and ball milling to ensure resin performance; it passes through a 100-200# sieve to ensure the resin powder particle size.

7. The method for preparing a grinding wheel for semiconductor packaging according to claim 4, characterized in that, The S3 mixing method uses a three-dimensional mixing machine with a mixing time of 40-60 minutes. After mixing, the mixture is passed through a 100-200# sieve.

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