Fixed abrasive nanogrinding plates, related articles and related methods

Abstract

The present disclosure relates to fixed abrasive grinding plates, fixed abrasive grinding tools formed therefrom, and related methods. Grinding plates generally have a composite structure with abrasive beads (e.g., beads containing diamond abrasive), porosity additives, and inorganic fillers and / or fluxing agents dispersed throughout a binder matrix formed from a polymeric resin (e.g., a cured thermosetting resin) or a glassy material (e.g., a fired vitrified glass frit matrix).

Description

[Technical Field]

[0001] This application claims priority to U.S. Provisional Application No. 63 / 427,531 (filed November 23, 2022) and U.S. Provisional Application No. 63 / 458,253 (filed April 10, 2023), both of which are incorporated herein in their entireties.

[0002] There are no government conflicts of interest listed.

[0003] This disclosure relates to fixed abrasive grinding plates and segments thereof suitable for use in precision grinding and polishing (particularly nanogrinding) of advanced materials such as sapphire, titanium carbide-reinforced alumina (AlTiC), silicon carbide (SiC), gallium nitride (GaN), aluminum nitride (AlN), zinc selenide (ZnSe), and other compound semiconductor materials, as well as glass, ceramic, metal, and composite materials. The disclosed fixed abrasive grinding plates utilize diamond beads or a mixture of abrasive particles and metal oxide beads, and fillers bound together with one or more binders and additives, to achieve very smooth surfaces with low surface roughness for a wide range of workpieces, combined with the relatively low material removal rates desired in nanogrinding processes. [Background technology]

[0004] Chemical mechanical planarization (CMP) of workpieces on a pad or rigid plate is a common practice in the polishing industry for AlTiC, SiC, GaN, AlN, ZnSe, and other similar materials. In the hard disk drive industry, this process includes rough lap polishing and mirror lap polishing. Rough lap polishing uses the so-called free-abrasive lapping method and fixed-abrasive lapping method. The workpiece is brought into contact with a lathe plate and conditioning ring for planarization while a diamond slurry is dripped onto the plate. Diamond particles are embedded in a metal lathe plate (usually made of zinc, tin, or tin alloy) to form a two-body system, while other particles roll between the plate and the workpiece in a three-body system. The use of free-abrasive and fixed-abrasive diamonds results in high material removal rates but also high surface roughness. Surface roughness can be improved by adding a separate process called fixed-abrasive lapping. In this process, the workpiece is lapped against a lathe plate pre-embedded with diamond particles using a lubricant that does not contain any aggressive abrasives. Fixed-abrasive lapping allows for slower lapping speeds and better surface finishes. While combining free and fixed abrasives improves the surface finish of magnetic heads, handling loose diamond slurries still presents some drawbacks in terms of loading efficiency and uniformity. Only about 10% of the diamonds in the dispensed slurry are embedded in the plate, with the remainder dripping into a waste collection area. As lapping progresses, the embedded diamond particles are forced further into the plate, potentially causing some diamonds to break off and scratch the workpiece. The loaded diamonds have a limited lifespan per run, requiring reloading, and only a small percentage of the diamond particles actually remain embedded in the plate.

[0005] Lapping and polishing can be performed using diamond abrasive films, consisting of a flexible backing (e.g., PET, Mylar) coated with a layer of abrasive diamonds and a binder (e.g., nylon, polyester, epoxy resin, UV-curable resin), mounted on a rigid substrate that serves as the lapping plate. U.S. Patents 6,458,018, 6,634,929, and 6,722,952 incorporate diamond beads into an abrasive coating suitable for polishing glass or ceramic workpieces. This abrasive contains a three-dimensional structured coating on a flexible substrate. This structured fixed-abrasive coating is suitable for rough lapping but not for mirror lapping, where surface finish is critical. The discontinuous three-dimensional coating has sharp edges that can scratch the workpiece. Polishing pads are known to be unable to maintain good flatness during long lapping periods, resulting in the disadvantage of rounding the wafer edges. These abrasive films have a short service life and must be replaced frequently.

[0006] In U.S. Patents 8,628,383, 8,888,878, and 8,038,751, coated abrasive products are manufactured using diamond beads and aggregates made from abrasive particles and nanoparticle binders. In some cases, abrasive aggregates can be coated onto a flexible backing to form fixed-abrasive pads. While these pads have good polishing efficiency, they have poor surface finish. When used for wafer lapping, these pads are difficult to maintain good flatness over long periods of time, and edge rounding remains a problem. Coated abrasive products have also been customized for grinding wheels where surface finish is not critical or for general-purpose grinding. Grinding wheels come in a variety of sizes, shapes, and configurations, including standard wheel shapes, cup wheel shapes, mount point shapes, and honing stone shapes. The type of binder used to bind the abrasive matrix determines the type of grinding wheel. Ceramic-bond abrasive matrices are called vitreous-bond wheels, which account for the majority of grinding wheels. Organic polymer bonded wheels are called resin-bonded grinding wheels, while metal bonded wheels are called metal-bonded grinding wheels. Vitreous bonded grinding wheels have been applied to precision nanogrinding of hard materials, including SiC, as demonstrated by Huo, Vacassy, ​​and Amino. U.S. Patent No. 6,394,888 teaches a method for producing highly porous, low-abrasive resin-bonded grinding wheels. The abrasive was directly bonded to a rigid backing for easy attachment to the wheelbase.

[0007] U.S. Patent Publication No. 2019 / 0255676 relates to three-dimensional fixed abrasive plates for lapping and polishing that generally require harder composite / matrix materials to achieve high material removal rates suitable for lapping and polishing. Summary of the Invention [Means for solving the problem]

[0008] In one aspect, the present disclosure relates to a resin-bonded abrasive grinding plate, such as a bonded abrasive grinding plate (or segment thereof), comprising: a) a plurality of micron-sized composite abrasive beads (e.g., spherical or quasi-spherical abrasive beads) in an amount of 30% to 95% by weight based on the dry weight of the grinding plate; b) at least one porous additive in an amount of 1% to 40% by weight based on the dry weight of the grinding plate; c) one or more inorganic fillers in an amount of 1% to 40% by weight based on the dry weight of the grinding plate; and d) at least one polymeric resin in an amount of 3% to 40% by weight based on the dry weight of the grinding plate. The polymeric resin comprises (spherical) abrasive beads (e.g., the porous additive and inorganic filler(s) are present as dispersed components in a composite structure with the polymeric resin as a binder matrix), and the grinding plate has a hardness ranging from 20 to 120 on the Rockwell L scale. Optionally, the grinding plate has a hardness of 1.0 g / cm. 3 ~1.8g / cm 3 The grinding plate of this form may be free of, or substantially free of, a glassy (or glassy frit) matrix material, and may, for example, include only a polymeric resin as the grinding plate binder. The above components and properties are equally applicable to grinding plate segments (e.g., segments or portions cut therefrom) incorporated into a grinding tool, such as a grinding wheel comprising a base plate and a plurality of grinding plate segments attached to or bonded to the base plate.

[0009] In one aspect, the present disclosure relates to a vitreous fixed abrasive grinding plate, such as a fixed abrasive grinding plate (or segment thereof), comprising: a) a plurality of micron-sized composite abrasive beads (e.g., spherical or quasi-spherical abrasive beads) in an amount of 30% to 95% by weight based on the dry weight of the grinding plate; b) at least one porous additive in an amount of 1% to 40% by weight based on the dry weight of the grinding plate; c) one or more fluxing agents in an amount of 1% to 40% by weight based on the dry weight of the grinding plate; and d) a vitreous matrix in an amount of 3% to 40% by weight based on the dry weight of the grinding plate. The vitreous matrix bonds to the (spherical) abrasive beads (e.g., the porous additive and inorganic filler(s) are dispersed in a composite structure with the vitreous matrix as a binder matrix). Optionally, the grinding plate has a saturation of 0.7 g / cm. 3 ~1.3g / cm 3 The grinding plate of this form may be free of, or substantially free of, a polymer resin matrix material, and may, for example, include only a glassy (or glassy frit) material as the matrix material of the grinding plate. The above components and properties are equally applicable to grinding plate segments (e.g., segments or portions cut therefrom) incorporated into a grinding tool, such as a grinding wheel comprising a base plate and a plurality of grinding plate segments attached to or bonded to the base plate.

[0010] The disclosed fixed abrasive grinding plates and segments thereof are susceptible to various modifications, whether on the resin side, the vitreous side, or both sides of the grinding plate.

[0011] In some refinements, the abrasive beads have an (average) particle size in the range of 5 nm to 50 nm or 5 nm to 40 nm, and / or each abrasive bead comprises (i) a plurality of abrasive particles having an (average) particle size in the range of 5 nm to 12 μm or 10 nm to 10 μm, and (ii) an inorganic metal oxide binder (e.g., as a coating or matrix containing the plurality of abrasive particles within the composite abrasive bead). For example, the abrasive beads may have a size or average size of at least 5, 7, 10, 12, 15, 20, or 25 μm, and / or at most 10, 15, 20, 25, 30, 35, 40, 45, or 50 μm. Alternatively, or in addition, the abrasive particles may have a size or average size of at least 0.005, 0.01, 0.02, 0.025, 0.035, 0.05, 0.1, 0.2, 0.5, 1, 1.5, 2, or 3 μm, and / or up to 0.05, 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 10, or 12 μm. The average size disclosed herein can represent a weight-average size, a volume-average size, or an area-average size. Similarly, the particle size ranges disclosed herein can represent upper and lower limits of a particle size distribution based on weight, volume, or area (e.g., 1% / 99%, 2% / 98%, 5% / 95%, or 10% / 90% of the cumulative particle size distribution). Alternatively, or in addition, the particle sizes disclosed herein can represent the minimum or maximum size in a particle size distribution obtained, for example, from sieving, classification, or other particle size classification means.

[0012] In a further refinement, the abrasive particles are selected from the group consisting of natural diamond, synthetic diamond, cubic boron nitride, silicon carbide, and combinations thereof, and the inorganic metal oxide binder is selected from the group consisting of silicon dioxide, titanium dioxide, cerium oxide, zirconium oxide, aluminum oxide, and mixtures thereof. The abrasive particles are present in an amount of 20% to 90% by weight of the abrasive beads (e.g., the remainder being the inorganic metal oxide binder). For example, the abrasive particles can be present in an amount of at least 20, 25, 30, 35, 40, 45, 50, 55, or 60% by weight, and / or up to 40, 45, 50, 55, 60, 65, 70, 80, or 90% by weight of the abrasive beads. Alternatively, or in addition, the inorganic metal oxide binder can be present in an amount of at least 10, 20, 30, 40, 50, or 60% by weight, and / or up to 30, 40, 50, 60, 70, or 80% by weight, based on the abrasive beads. In embodiments, the abrasive beads contain no more than 0.01, 0.1, or 1% by weight of materials other than abrasive particles and inorganic metal oxide binder.

[0013] In an improved form of the resin grinding plate, the weight ratio of (i) polymeric resin to (ii) porous additive in the grinding plate is in the range of 1 to 4, and / or the combined amount of polymeric resin and porous additive in the grinding plate is at least 35 wt. % based on the dry weight of the grinding plate.

[0014] In an improved form of the resin grinding plate, the weight ratio of (i) polymer resin to the combined amount of (ii) porous additive and inorganic filler in the grinding plate is in the range of 0.8 to 1.5, and / or the combined amount of polymer resin, porous additive, and inorganic filler in the grinding plate is at least 50 wt. % based on the dry weight of the grinding plate.

[0015] In an improved form of the vitreous grinding plate, the weight ratio of (i) vitreous matrix to (ii) porous additive in the grinding plate is in the range of 1 to 4, and the combined amount of vitreous matrix and porous additive in the grinding plate is at least 30 wt. % based on the dry weight of the grinding plate.

[0016] In an improved form of the vitrified grinding plate, the weight ratio of (i) the vitreous matrix to the combined amount of (ii) the porous additive and the fluxing agent in the grinding plate is in the range of 0.8 to 1.5, and the combined amount of the vitreous matrix, the porous additive, and the fluxing agent in the grinding plate is at least 40 wt. % based on the dry weight of the grinding plate.

[0017] In one embodiment, the surface porosity of the grinding plate is between 5% and 60%, or between 3% and 60%, and / or the pores in the grinding plate are not uniform, regular, or interconnected throughout the thickness of the grinding plate. For example, the grinding plate can have a surface porosity of at least 3, 5, 7, 10, 15, 20, 25, 30, or 40%, and / or up to 10, 20, 30, 40, 50, or 60%.

[0018] In one embodiment, the polymer resin in the resin grinding plate is selected from the group consisting of benzoxazine resins, base-catalyzed phenolic resins, acid-catalyzed phenolic resins, epoxy resins, unsaturated polyester resins, and mixtures thereof. Benzoxazine resins are particularly suitable due to their excellent hardness and extremely low water absorption. Benzoxazine resins can be produced by ring-opening crosslinking polymerization or copolymerization of unsubstituted or substituted benzoxazine monomers (e.g., 3-phenyl-2,4-dihydro-1,3-benzoxazine monomer, a representative phenyl-substituted benzoxazine monomer). In an embodiment, the polymer resin can include one or more benzoxazine resins and one or more polymer resins other than benzoxazine resins, such as phenolic resins and epoxy resins. For example, one or more benzoxazine resins can be present in an amount of at least 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, or 70 wt.%, and / or up to 40, 45, 50, 55, 60, 65, 70, 80, 90, or 95 wt.%, based on the total polymer resin. Similarly, one or more polymer resins other than benzoxazine resins can be present in an amount of at least 5, 15, 25, 35, 45, 55, or 65 wt.%, and / or up to 30, 40, 50, 60, 70, or 80 wt.%, based on the total polymer resin.

[0019] In one refinement of the vitreous grinding plate, the vitreous matrix includes silica (SiO) and one or more of lithium oxide (LiO), sodium oxide (NaO), potassium oxide (KO), boron trioxide (BO), aluminum oxide (AlO), calcium oxide (CaO), magnesium oxide (MgO), barium oxide (BaO), zirconium oxide (ZrO), zirconium dioxide (ZrO), titanium dioxide (TiO), zinc oxide (ZnO), calcium difluoride (CaF), manganese dioxide (MnO), and bismuth trioxide (BiO). For example, silica can be present in the vitreous matrix in an amount of at least 20% by weight, and one or more of sodium oxide, potassium oxide, aluminum oxide, calcium oxide, and barium oxide can be individually present in the vitreous matrix in an amount ranging from 3% to 30% by weight. Optionally, boron trioxide may also be present in the vitreous matrix in an amount of at least 3% by weight, with the oxides and relative amounts similarly applying to the glass frit powder used to form the vitreous matrix.

[0020] In refinements of the vitreous grinding plate, the vitreous matrix and / or its corresponding glass frit material can be characterized according to one or more of its linear thermal expansion coefficient, transformation temperature, and softening temperature. In one embodiment, the vitreous matrix or its glass frit material has a linear thermal expansion coefficient of 20×10 -7 / K~200×10 -7 / K (or 50-100 x 10 -7 / K; evaluated at 20 to 400°C). In one embodiment, the vitreous matrix or its glass frit material can have a transformation temperature in the range of 400°C to 800°C (or 400 to 600°C). In one embodiment, the vitreous matrix or its glass frit material can have a softening temperature in the range of 500°C to 1000°C (or 500 to 700°C).

[0021] In one embodiment, the porous additive comprises hollow glass spheres having an average diameter ranging from 10 μm to 200 μm, or from 1 μm to 500 μm. More generally, the hollow glass spheres or other porous additives can have a particle size or average particle size of at least 1, 2, 5, 10, 15, 20, 30, 40, 60, 80, or 100 μm, and / or up to 10, 20, 30, 40, 50, 70, 100, 150, 200, 300, 400, or 500 μm. As noted above, the particle size can represent an average particle size or particle size distribution based on weight, volume, or area, a maximum or minimum particle size, etc.

[0022] In one embodiment, the inorganic filler is selected from the group consisting of calcium carbonate, calcium metasilicate, talc, kaolin, calcium oxide, and mixtures thereof.

[0023] In one embodiment, the fluxing agent is selected from the group consisting of clay, kaolin, feldspar (aluminum tectosilicate), borax (hydrated or anhydrous sodium borate), talc, wollastonite (calcium metasilicate), lithium, sodium and potassium nitrates, lithium, sodium and potassium carbonates, and combinations thereof.

[0024] In one embodiment, the grinding plate further includes at least one oxidizer, such as permanganate, periodate, iodate, chlorate, ammonium cerium nitrate, and / or persulfate, including, for example, potassium salts, alkali metal salts, or other salts thereof. More generally, the grinding plate can include one or more chemicals or oxidizers that react with the workpiece during machining to improve material removal and / or surface finish. Such chemicals or oxidizers, whether potassium permanganate, potassium periodate, or others, can be included in the grinding plate in an amount of 0.1% to 5% by weight, e.g., at least 0.1, 0.2, 0.5, 1, 1.5, or 2% by weight, and / or up to 1, 2, 3, 4, or 5% by weight, based on the dry weight of the grinding plate.

[0025] In another aspect, the present disclosure relates to a fixed-abrasive grinding tool including a base plate (e.g., a steel or other support substrate adapted to rotate in a grinding or polishing process using the tool) and a plurality of fixed-abrasive grinding segments (e.g., as separate, individual grinding elements on the base plate) attached to the base plate. The fixed-abrasive grinding segments include fixed-abrasive grinding plates according to any of the various disclosed refinements, embodiments, etc., or portions thereof (e.g., portions cut out from the base grinding plate to provide the segments), such as resin grinding plates or vitreous grinding plates.

[0026] In one refinement, the fixed abrasive grinding tool is in the form of a grinding wheel, such as a cup wheel. In contrast to a monolithic lapping plate structure, a grinding wheel tool typically includes multiple, distinctly different grinding (or nanogrinding) elements. Grinding wheels come in a variety of shapes (commonly referred to as "types") conforming to the ANSI B74.2 standard. For most applications, an appropriate wheel shape can be selected from these standard structures. Examples of typical grinding wheel shapes / structures include straight, cylindrical, one-sided concave, two-sided concave, saucer, straight cup, flared cup, dish, cone, square plug, round plug, one-sided partial removal, two-sided partial removal, one-sided partial removal and two-sided concave, one-sided partial removal and one-sided concave, one-sided partial removal and two-sided concave, one-sided partial removal and two-sided concave, convex hub disc wheel, and convex hub dish wheel.

[0027] In another aspect, the present disclosure relates to a fixed abrasive grinding kit including a plurality of fixed abrasive grinding tools according to the present disclosure, wherein (i) at least one fixed abrasive grinding tool comprises at least one polymer resin, and (ii) at least one fixed abrasive grinding tool comprises a vitreous matrix. Two different grinding tool combinations can be used sequentially in machining a substrate. A vitreous grinding plate according to the present disclosure can be used in a first machining step, generally providing a relatively high material removal rate but a relatively coarse surface finish or roughness. A resin grinding plate according to the present disclosure can be used in a second machining step, generally providing a relatively low material removal rate but a relatively fine / smooth surface finish with low roughness.

[0028] In another aspect, the present disclosure relates to a method of machining a substrate, the method comprising performing at least one of grinding and polishing on the substrate using a fixed abrasive grinding tool according to any of the disclosed improvements, embodiments, etc. In an embodiment, the method comprises performing nanogrinding as the grinding operation on the substrate. While grinding processes are generally high material removal processes using large diamond sizes, nanogrinding typically uses abrasives with submicron abrasive particles to achieve good surface finish with little or no material removal. Nanogrinding as an operation can achieve the results of a polishing operation (e.g., in terms of low surface roughness), but is generally considered to be distinct from polishing methods.

[0029] In one refinement, particularly when using a resin grinding plate, the substrate has an initial surface roughness Ra of at least 30 nm or 10 nm before grinding and / or polishing, and the substrate has a final surface roughness Ra of 1 nm or less after grinding and / or polishing, and / or the average material removal rate from the substrate during grinding and / or polishing (e.g., between the initial and final states of the substrate) is 1 μm / min or less. The surface roughness Ra represents the arithmetic mean of the deviations of the profile height from the mean line of the surface. In some embodiments, the substrate has a final roughness parameter Rt of 30 nm or less or 20 nm or less after grinding and / or polishing. The roughness parameter Rt is the vertical distance between the highest peak and the lowest peak of the surface roughness profile within the entire measurement distance (i.e., the maximum peak-to-valley height). In other words, it is the height difference between the highest peak and the lowest valley within the measurement range. In some embodiments, after grinding and / or polishing, the substrate has a final roughness parameter Rv between 0 nm and -25 nm, or between 0 nm and -10 nm. The roughness parameter Rv is the average valley depth across the measured surface. Surface roughness parameters can be measured using any suitable device known in the art, for example, an optical surface inspection device such as a Zygo NEWVIEW 6k Optical Profilometer (available from Zygo Corporation, Middlefield, Connecticut).

[0030] In one refinement, particularly when using a vitreous grinding plate, the substrate has an initial surface roughness Ra of at least 100 nm, 200 nm, or 300 nm before grinding and / or polishing, and the substrate has a final surface roughness Ra of 5 nm or less after grinding and / or polishing, and the average material removal rate from the substrate during grinding and / or polishing ranges from 2 μm / min to 10 μm / min.

[0031] In one refinement, the method includes grinding and / or polishing the substrate with a first bonded abrasive grinding tool comprising a glassy matrix, followed by grinding and / or polishing the substrate with a second bonded abrasive grinding tool comprising at least one polymeric resin. As described above, a sequential machining operation including a first, high-speed / coarse machining initial step using the glassy tool and a second, slower / fine machining subsequent step using the resin tool can provide an overall high-speed process (due to the high removal rate provided by the glassy tool) while achieving a sufficiently smooth final surface (due to the low surface roughness provided by the resin tool). Typically, the same type of tool is used in both steps (e.g., a glassy cup wheel and a resin cup wheel are used sequentially), although in some embodiments, different types of tool can be used in the two steps.

[0032] In one embodiment, the substrate is selected from the group consisting of sapphire, titanium carbide reinforced alumina (AlTiC), silicon carbide (SiC; e.g., (α)C-SiC, 4H-SiC, (β)H-SiC), gallium nitride (GaN), aluminum nitride (AlN), zinc selenide (ZnSe), silicon wafers (e.g., semiconductor silicon such as crystalline silicon), ceramic substrates, optical substrates (e.g., transparent glass or polymeric materials), and combinations thereof.

[0033] In another aspect, the present disclosure provides a method for forming a (resin) bonded abrasive grinding segment, the method comprising: hot-pressing, heat-assisted curing, and / or room-temperature curing a mixture to form a blank plate, the mixture comprising: a) a plurality of micron-sized composite (spherical) abrasive beads in an amount of 30% to 95% by weight of the mixture; b) at least one porous additive in an amount of 1% to 40% by weight of the mixture; c) one or more inorganic fillers in an amount of 1% to 40% by weight of the mixture; and d) at least one uncured polymeric resin in an amount of 3% to 40% by weight of the mixture. The blank plate is then cut to form a plurality of bonded abrasive grinding segments, each comprising a resin bonded abrasive grinding plate according to any of the disclosed refinements, embodiments, etc. (e.g., having the components and properties of the bonded abrasive grinding plate described above). The hot-pressed mixture can further include other desired additives or components of the final grinding segment, such as chemical agents or oxidizers.

[0034] In another aspect, the present disclosure relates to a method of forming a (vitreous) bonded abrasive grinding segment, the method comprising: firing a mixture to form a blank plate, the mixture comprising: a) a plurality of micron-sized composite (spherical) abrasive beads in an amount of 30% to 95% by weight of the mixture; b) at least one porous additive in an amount of 1% to 40% by weight of the mixture; c) one or more fluxing agents in an amount of 1% to 40% by weight of the mixture; d) a plurality of glass frits in an amount of 3% to 40% by weight of the mixture; and e) optionally, a binder (e.g., a gum) in an amount of up to 5% by weight of the mixture; and cutting the blank plate to form a plurality of bonded abrasive grinding segments, each comprising a vitreous bonded abrasive grinding plate according to any of the disclosed refinements, embodiments, etc. (e.g., having the components and properties of the bonded abrasive grinding plate).

[0035] In one refinement, the plurality of fixed abrasive grinding segments are cut from the interior of the blank plate (e.g., further excluding grinding segments from the exterior / periphery / edges of the blank plate).

[0036] In further refinements, the interior corresponds to an interior surface area in the range of 50%-80% or 40%-90% (e.g., at least 40%, 50%, 60%, or 70%, and / or up to 60%, 70%, 80%, or 90%) of the surface area of ​​the blank plate. For example, the outer 20%-50% or 10%-60% (e.g., at least 10%, 20%, 30%, or 40%, and / or up to 30%, 40%, 50%, or 60%) of the exterior / peripheral / edge surface area of ​​the blank plate face is not cut into grinding elements or incorporated into the corresponding grinding tool. Alternatively or additionally, the interior can be defined by an excluded periphery defined based on an absolute value (or length). For example, the excluded perimeter can range from 0.25 cm to 5 cm or 1 cm to 2.5 cm (or about 0.1 to 2 inches or 0.5 to 1 inch) (e.g., at least 0.25, 0.5, 0.75, 1, 1.25, or 1.5 cm, and / or at most 1, 1.5, 2, 2.5, 3, 4, or 5 cm). For example, for a 7.5 inch by 7.5 inch (19.1 cm by 19.1 cm) blank plate, a 1 inch (2.5 cm) excluded perimeter would result in an interior central area of ​​5.5 inches by 5.5 inches (14.0 cm by 14.0 cm), and a 0.5 inch (1.3 cm) excluded perimeter would result in an interior central area of ​​6.5 inches by 6.5 inches (16.5 cm by 16.5 cm).

[0037] In one refinement, the method further includes bonding a plurality of fixed abrasive grinding segments to a base plate and planarizing the plurality of fixed abrasive grinding segments to a flat state (e.g., a consistent height of the initial grinding elements in the manufactured fixed abrasive grinding tool).

[0038] In one refinement, the method of forming the resin blank plate includes hot pressing the mixture in a mold at a temperature of 240°F to 580°F (or about 120°C to 300°C) and a pressure of 200 psi to 2000 psi (or about 13.8 bar to 138 bar). The thickness of the blank plate ranges from 0.1 inch to 1 inch (about 0.25 cm or 0.5 cm to 1 cm or 2.5 cm). The lateral dimensions of the blank plate range from 1 inch to 60 inches (about 2.5 cm to 150 cm). More typically, the lateral dimensions can be at least 2, 5, 10, 15, 20, 25, 40, 60, or 80 cm, and / or at most 4, 8, 12, 16, 20, 30, 40, 50, 70, 100, 120, or 150 cm. The lateral dimension may define one of two opposing faces of the blank plate, for example the length and width of a rectangular plate (the length and width are the same for a square plate), or the diameter of a circular plate.

[0039] In one refinement, a method for forming a vitreous blank plate includes cold-pressing the mixture in a mold at a temperature of 50°F to 200°F (or about 10°C to 90°C) and a pressure of 300 psi to 1000 psi (or about 20 bar to 70 bar) to form a green part, optionally drying the green part to remove water present in the mixture (e.g., some of the adhesive or binder), and firing the (dried) green part at a temperature of 1000°F to 1400°F (or about 540°C to 760°C). The thickness of the blank plate ranges from 0.1 inch to 1 inch (or about 0.25 cm to 2.5 cm), and the lateral dimensions of the blank plate range from 1 inch to 20 inches (or about 2.5 cm to 50 cm). More typically, the lateral dimensions are at least 2, 5, 10, 15, 20, 25, or 40 cm, and / or can be up to 4, 8, 12, 16, 20, 30, 40, or 50 cm. Firing generally involves heating at a controlled rate (e.g., 50-250°C / hr, 100-200°C / hr, or about 150°C / hr) until the target temperature is reached, followed by holding at the target temperature for up to 6 hours (e.g., 0-6 hours, 0.1-5 hours, 1-4 hours), followed by allowing the fired material to cool naturally to ambient temperature. No external pressure is typically applied during firing. Firing can be carried out in an air atmosphere, but other inert or non-oxidizing atmospheres, such as nitrogen or argon, are also possible.

[0040] While the disclosed compositions and methods may be embodied in various forms, specific embodiments of the present disclosure are illustrated (described below) with the understanding that the present disclosure is intended to be exemplary and is not intended to limit the scope of the claims to the specific embodiments described and exemplified herein. [Brief explanation of the drawings]

[0041] FIG. 1 shows spray-dried abrasive beads incorporating single crystal diamond according to one embodiment of the present disclosure.

[0042] FIG. 2 illustrates a fixed abrasive grinding tool incorporating multiple fixed abrasive grinding plates or segments according to the present disclosure.

[0043] FIG. 3 illustrates an alternative construction of a fixed abrasive grinding tool according to the present disclosure.

[0044] FIG. 4 illustrates a fixed abrasive grinding plate according to the present disclosure.

[0045] FIG. 5 illustrates an exemplary hardness distribution as a function of sample position for a fixed abrasive grinding plate according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0046] The present disclosure relates to fixed-abrasive grinding plates, fixed-abrasive grinding tools formed therefrom, and related methods. Grinding plates generally have a composite structure with abrasive beads (e.g., beads containing diamond abrasive), porous additives, and inorganic fillers dispersed throughout a binder matrix formed from a polymer resin (e.g., a cured thermosetting resin). Because grinding plates generally have a relatively low hardness, especially compared to other grinding and polishing materials such as those used for lapping plates, grinding tools formed from the plates (or segments thereof) are particularly suited to nanogrinding operations, where very low surface roughness values ​​can be achieved with relatively little substrate material removal. Such nanogrinding is particularly useful for machining very smooth surfaces of advanced materials such as sapphire, titanium carbide-reinforced alumina (AlTiC), silicon carbide (SiC), gallium nitride (GaN), aluminum nitride (AlN), zinc selenide (ZnSe), and other composite semiconductor materials.

[0047] Grinding Plate Compositions, Articles, and Methods A fixed abrasive grinding plate 100 (FIG. 4) according to the present disclosure generally has a composite structure comprising approximately 30-95% by weight of micron-sized composite abrasive beads, approximately 1-40% by weight of one or more porous additives, approximately 1-40% by weight of one or more inorganic fillers, and approximately 3-40% by weight of one or more polymeric resins. The polymeric resin provides a binder (or continuous binder matrix) for the abrasive beads, porous additives, and inorganic fillers bound by (or dispersed throughout) the polymeric resin. Grinding plates or related components according to the present disclosure that include one or more polymeric resins as a composite matrix are also referred to herein as resin grinding plates, resin grinding segments, resin tools, etc. FIG. 4 shows an equivalent representation of a fixed-abrasive grinding plate 100 according to the present disclosure, which generally has a composite structure including approximately 30-95% by weight of micron-sized composite abrasive beads, approximately 1-40% by weight of one or more porosity additives, approximately 1-40% by weight of one or more fluxing agents, and approximately 3-40% by weight of a vitreous matrix. The vitreous matrix is ​​produced by sintering a glass frit powder, and the resulting vitreous material provides a binder (or continuous binder matrix) for the abrasive beads, porosity additives, fluxing materials, and any inorganic fillers bound by (or dispersed throughout) the vitreous matrix. Grinding plates or related components according to the present disclosure that include a vitreous material as a composite matrix are also referred to herein as vitreous grinding plates, vitreous grinding segments, vitreous tools, etc. References herein to grinding plates, grinding segments, tools, etc. generally apply to either resin or vitreous embodiments. The amounts may be expressed as dry weight relative to the total weight of the grinding plate. The components, amounts, and properties of grinding plate 100 equally apply to grinding segment 220 of plate 100. This segment 220 is incorporated into a fixed abrasive grinding tool 200 (FIG. 2) that uses segment 220 as the working element that contacts the workpiece, such as during nano-grinding.

[0048] As described in more detail below, composite abrasive beads include diamond abrasive particles or the like bonded or coated with an inorganic metal oxide binder. The abrasive beads can be present in the grinding plate in an amount of at least 30, 35, 40, 45, 50, 55, 60, 65, or 70 weight percent, and / or up to 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95 weight percent, based on the grinding plate or segment thereof. The amounts described above can apply to the total amount of abrasive beads when more than one type of abrasive bead is present.

[0049] As described in more detail below, porous additives include, among others, hollow glass spheres. The porous additives can be present in the grinding plate in an amount of at least 1, 2, 3, 5, 7, 10, 15, or 20% by weight, and / or up to 10, 15, 20, 25, 30, 35, or 40% by weight, based on the grinding plate or segment thereof. The amounts above can apply to the total amount of porous additives when two or more porous additives are present.

[0050] As described in more detail below, inorganic fillers include, among others, calcium carbonate and / or talc. The inorganic filler can be present in the grinding plate in an amount of at least 1, 2, 3, 5, 7, 10, 15, or 20% by weight, and / or up to 10, 15, 20, 25, 30, 35, or 40% by weight, based on the grinding plate or its segments. The amounts above can apply to the total amount of inorganic fillers when two or more inorganic fillers are present.

[0051] As described in more detail below, the fluxing agent can include, among others, feldspar. The fluxing agent can be present in the grinding plate in an amount of at least 1, 2, 3, 5, 7, 10, 15, or 20% by weight and / or up to 10, 15, 20, 25, 30, 35, or 40% by weight of the grinding plate or segment thereof. The amounts mentioned above can apply to the total amount of fluxing agent when more than one type of fluxing agent is present.

[0052] As described in more detail below, polymeric resins include, among others, benzoxazine resins, phenolic resins, and / or epoxy resins. The polymeric resin can be present in the grinding plate in an amount of at least 3, 5, 7, 10, 15, 20, or 25% by weight, and / or up to 15, 20, 25, 30, 35, or 40% by weight, based on the grinding plate or its segments. The amounts apply to the total amount of polymeric resin when more than one type is present.

[0053] As described in more detail below, the vitreous matrix can include, among others, silica and one or more oxides, such as boron trioxide, sodium oxide, potassium oxide, aluminum oxide, calcium oxide, and barium oxide. The vitreous matrix can be present in the polishing plate in an amount of at least 3, 5, 7, 10, 15, 20, or 25 wt. % and / or up to 15, 20, 25, 30, 35, or 40 wt. % of the polishing plate or segment thereof. The amounts described above apply to the total amount of vitreous matrix material when two or more oxides are present. The amounts described above also apply to the amount of glass frit powder mixed with other polishing plate components to form the initial blank plate.

[0054] Resin grinding plates generally have a relatively low hardness, which facilitates nano-grinding processes that produce low surface roughness, low removal rates, and very smooth surfaces on a wide range of workpieces. In embodiments, the grinding plates have a hardness value ranging from 20 to 120 on the Rockwell Hardness L scale. For example, the hardness value can be at least 20, 30, 40, 50, 60, 70, or 80, and / or up to 40, 50, 60, 70, 80, 90, 100, 110, or 120. Rockwell hardness values ​​and scales are generally known in the art and can be measured using any suitable method and apparatus, such as ASTM D785. The Rockwell test is a common method for measuring the bulk hardness of various materials, including metallic, polymeric, and composite materials. While hardness testing does not directly measure performance characteristics, material hardness is directly correlated to strength, wear resistance, and other properties. The Rockwell test measures the penetration depth of an indenter under a large load (primary load) compared to the penetration depth of an indenter under a preload (secondary load). The equation for Rockwell hardness is HR = N-hd, where d is the depth in mm (from the zero load point), N and h are scale factors depending on the scale of the test used. For the Rockwell hardness L scale, typically the minor load is 10 kgf, the major load is 60 kgf, the indenter is a 0.25 inch (6.35 mm) ball, N is 130, and h is 500.

[0055] The calculated density of the resin grinding plate is 0.8 g / cm 3 ~1.8g / cm 3 or 1.0 g / cm 3 ~1.8g / cm 3 The calculated density of the vitreous ground plate can be in the range of 0.7 g / cm 3 ~1.3g / cm 3 In embodiments, the calculated density of any grinding plate can be in the range of at least 0.7, 0.8, 0.9, 1, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, or 1.4 g / cm 3, and / or up to 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2 g / cm 3 The calculated density can be calculated as follows: For solids such as grinding plates, the volume can be determined by geometric measurements of the dimensions / edges to calculate the volume of the object. The calculated density can be determined based on the measured mass of the object divided by the calculated volume of the object. The calculated density represents a property corresponding to the suitability of the grinding plate for nanogrinding. Similar to hardness, a lower calculated density indicates lower strength and potentially more brittleness. In contrast, materials suitable for lapping operations typically have higher hardness and / or higher calculated density values. The density of the grinding plate can be controlled or adjusted based on the press pressure used to form the grinding plate.

[0056] The relative and / or absolute amounts of the components constituting the grinding plate can be selected to impart physical, mechanical, and / or chemical properties (e.g., hardness) to the grinding plate that are particularly suitable for nanogrinding. In particular, the binder serves to control the hardness and brittleness of the grinding plate. For example, in embodiments, the weight ratio of (i) polymeric resin or glassy matrix to (ii) porous additive in the grinding plate can be in the range of 1 to 4 or 0.8 to 5, e.g., at least 0.8, 1, 1.2, 1.5, 2, or 2.5, and / or up to 1.7, 2, 2.2, 2.5, 3, 4, or 5. Alternatively or additionally, the combined amount of (i) polymeric resin or glassy matrix and (ii) porous additive in the grinding plate can be at least 30, 35, 40, or 45 wt. % and / or up to 40, 45, 50, 55, or 60 wt. % based on the dry weight of the grinding plate. Similarly, in embodiments, the weight ratio of (i) the polymeric resin or vitreous matrix to the combined amount of (ii) the porous additive and inorganic filler in the grinding plate ranges from 0.8 to 1.5 or from 0.6 to 1.8, e.g., at least 0.6, 0.7, 0.8, 0.9, 1, 1.1, or 1.2, and / or at most 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, or 1.8. Alternatively or additionally, the combined amount of the polymeric resin or vitreous matrix, porous additive, and inorganic filler or fluxing agent in the grinding plate can be at least 45, 50, 55, 60, or 65 wt. % and / or at most 60, 65, 70, or 75 wt. % based on the dry weight of the grinding plate. Alternatively or additionally, the hardness of the grinding plate can be controlled by adjusting the compression pressure of the mixed components during plate formation. For example, the applied compression pressure can be between about 200 psi and 2000 psi (or between about 13.8 bar and 138 bar), or between 1000 psi and 1200 psi (or between about 68.9 bar and 82.7 bar).

[0057] FIG. 2 illustrates a fixed-abrasive grinding tool 200 according to the present disclosure. The tool 200 includes a base plate 210, which can be steel, stainless steel, other metal, or other support substrate configured to rotate during a machining process (e.g., nanogrinding) using the tool 200. A plurality of fixed-abrasive grinding segments 220 are attached to the base plate 210, e.g., as separate, individual grinding elements. The grinding segments 220 can generally have the same components, quantities, and properties as the grinding plate 100, e.g., when segments 220 of appropriate size / shape are cut from a single grinding plate 100 and bonded, attached, or otherwise secured to the base plate in a desired orientation. FIG. 3 illustrates another exemplary configuration of a grinding tool 200 according to the present disclosure, all of which include a support plate or base plate 210 to which the grinding segments 220 are attached.

[0058] The specific structure of the fixed abrasive grinding tool is not particularly limited. In an embodiment, the fixed abrasive grinding tool is in the form of a grinding wheel, such as a cup wheel shown in FIG. 2. In contrast to an integrated lapping plate structure, a grinding wheel tool typically includes multiple separate, discrete grinding (or nano-grinding) elements. Grinding wheels are available in a variety of shapes (commonly referred to as "types") generally recognized by the ANSI B74.2 standard. For most applications, an appropriate wheel shape can be selected from these standard structures. Examples of typical grinding wheel shapes / structures include straight, cylindrical, one-sided concave, double-sided concave, saucer, straight cup, flared cup, dish, cone, square plug, round plug, one-sided partial removal, double-sided partial removal, one-sided partial removal and double-sided concave, one-sided partial removal and one-sided concave, one-sided partial removal and double-sided concave, double-sided partial removal and one-sided concave, double-sided partial removal and double-sided concave, convex hub disc wheel, and convex hub dish wheel.

[0059] The grinding tool 200 can be used to process a variety of substrates or workpieces (e.g., by rotating the grinding tool at high speed and then contacting the rotating tool with the substrate). In embodiments, the substrate or workpiece can include advanced materials such as sapphire, titanium carbide-reinforced alumina (AlTiC), silicon carbide (SiC, e.g., (α)C-SiC, 4H-SiC, (β)H-SiC), gallium nitride (GaN), aluminum nitride (AlN), zinc selenide (ZnSe), silicon wafers (e.g., semiconductor silicon such as crystalline silicon), and other compound semiconductor materials. In other embodiments, the substrate or workpiece can include glass, ceramic, metal, or (polymer) composite materials.

[0060] In an embodiment, the processing method includes performing nanogrinding as a grinding operation on a substrate. While grinding processes typically involve high material removal using large diamond particles, nanogrinding uses an abrasive containing submicron abrasive particles to achieve good surface finish with little or no material removal. Most grinding wheels use high-grit diamonds in a vitreous bond to achieve fast polishing regardless of surface finish. If submicron diamond abrasives are used directly in a vitreous bond, the high temperature conditions encountered during grinding treatment of the vitreous bond oxidize / graphitize most of the diamonds, and the remaining diamond abrasives typically agglomerate. Incorporating diamonds into beads ensures good dispersion of the diamond abrasives. Oxidation and / or graphitization of diamond abrasives is avoided by incorporating diamond abrasive beads into resin-bonded grinding plate formulations and processing at much lower temperatures (e.g., 120°C-300°C, e.g., at least 120°C, 150°C, or 180°C, and / or up to 200°C, 250°C, or 300°C). The use of submicron diamond abrasive beads (e.g., 5-40 μm beads containing nanoscale diamond abrasives) in the grinding plates and grinding segments of the present disclosure makes the grinding plates particularly suitable for nanogrinding, which can improve the surface finish of the workpiece with less abrasive volume. This reduces grinding and polishing times and improves overall processing efficiency.

[0061] As noted above, nanogrinding typically achieves a good surface finish with little or no material removal, especially when using resin grinding plates or tools. In embodiments, the substrate has an initial surface roughness Ra of at least 30 nm or at least 10 nm before nanogrinding. The substrate has a final surface roughness Ra of 1 nm or less after nanogrinding. The average material removal rate from the substrate during nanogrinding (e.g., between the substrate's initial and final states) is 1 μm / min or less. The surface roughness Ra represents the average arithmetic mean of the profile height deviations from the mean line of the surface. In embodiments, the initial surface roughness Ra is at least 10, 20, 30, 40, or 50 nm, and / or up to 40, 60, 80, or 100 nm. Alternatively or additionally, the final surface roughness Ra may be at most 0.1, 0.2, 0.4, 0.6, 0.7, 0.8, 0.9 or 1.0 nm, and / or at least 0.01, 0.02, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5 or 0.6 nm.

[0062] The surface finish can also be characterized by a roughness parameter, Rt. Rt is the vertical distance between the highest and lowest peaks of the surface roughness profile over the entire measurement distance (i.e., maximum peak height relative to valley depth). In other words, it is the height difference between the highest peak and the lowest valley within the measurement range. In embodiments, the final surface roughness, Rt, can be at least 0.1, 0.2, 0.5, 1, 2, 4, or 6 nm, and / or up to 10, 12, 15, 20, 25, or 30 nm.

[0063] The surface finish may be further characterized by a roughness parameter Rv, which is the average valley depth of the measured surface(s). In embodiments, the final surface roughness Rv may be between 0 nm and −25 nm, or between 0 nm and −10 nm, for example, at least −25, −20, −15, −10, −8, −7, −6, or −5 nm, and / or up to −4 nm, −3 nm, −2 nm, −1 nm, or 0 nm.

[0064] As noted above, nanogrinding can achieve good removal rates, especially when using vitreous grinding plates or tools. In embodiments, the substrate has an initial surface roughness Ra of at least 100 nm, 200 nm, or 300 nm before nanogrinding or other machining, and a final surface roughness Ra of 5 nm or less after nanogrinding or other machining, with an average material removal rate from the substrate during nanogrinding or other machining (e.g., between the initial and final states of the substrate) ranging from 1.5 to 10 μm / min, or 2 to 8 μm / min. In embodiments, the initial surface roughness Ra is at least 50, 100, 150, 200, 300, or 400 nm, and / or up to 200, 400, 600, or 1000 nm. Alternatively or additionally, the final surface roughness Ra can be up to 2, 2.5, 3, 3.5, 4, 4.5, or 5 nm, and / or at least 1, 1.2, 1.5, 2, or 2.5 nm. Alternatively or additionally, the removal rate may be at least 1.2, 1.5, 1.7, 2, 2.5 or 3 μm / min, and / or up to 3, 5, 7 or 10 μm / min.

[0065] Polishing beads Abrasive beads, such as diamond abrasive beads, are formed by spray drying. A slurry of abrasive particles is made by dispersing the abrasive particles in a liquid carrier in the presence of an inorganic binder, dispersant, and / or plasticizer. These components are thoroughly mixed using a propeller mixer, ultrasonic mixer, or other suitable dispersing mechanism to obtain a uniformly dispersed abrasive slurry. The slurry is then spray-dried to form spherical abrasive beads (FIG. 1). Abrasive particles suitable for embodiments of the present disclosure generally have a Mohs hardness greater than 5. Examples of abrasive particles include carbides such as silicon carbide and titanium carbide; oxides such as alumina, zirconium oxide, and silicon oxide; and nitrides such as cubic boron nitride, titanium nitride, and silicon nitride. In addition to natural diamond, single-crystal, polycrystalline, and surface-etched synthetic diamonds can also be used. Diamond is selected as the abrasive particle in some embodiments due to its hardness and chemical inertness.

[0066] In some embodiments, the abrasive beads are composites of a mixture of abrasives or composites of abrasives and metal oxides (e.g., inorganic metal oxides). In some embodiments, the abrasive beads are spherical. In some embodiments, the micron-sized spherical abrasive beads have an average particle size of 5 microns to 50 microns. In some embodiments, the abrasive particles contained in the abrasive beads have an average particle size of 0.01 microns to 10 microns.

[0067] The abrasive particles range in size from nano to micron, in shape from three-dimensional blocks to two-dimensional shapes, and in surface roughness from smooth to rough. The abrasive particles may be coated with organic, inorganic, or metallic coatings. The particle size of the abrasive particles may range from about 5 nm to about 12 microns in some embodiments, from about 50 nm to about 7 microns in other embodiments, and less than about 4 microns in still other embodiments. The abrasive particle composition of the spray-drying slurry may range from about 1 wt % to about 50 wt % in some embodiments, and from about 5 wt % to about 35 wt % in other embodiments, based on the weight of the spray-drying slurry. In some embodiments of the present disclosure, a mixture of two or more particle sizes is used to achieve the desired lapping / polishing results.

[0068] In some embodiments, the abrasive particles are superabrasive particles. Superabrasive particles include natural diamond, synthetic diamond, and cubic boron nitride.

[0069] The abrasive particles are then mixed with an inorganic metal oxide binder to form, in some embodiments, a sprayable slurry / sol. The metal oxide binder forms a brittle, continuous matrix that binds the abrasive particles together. Suitable metal oxide binders include ceria, silica, zirconia, alumina, titanium dioxide, magnesium oxide, and mixtures thereof. In many embodiments, silica is used as the metal oxide binder. Silica is available as colloidal silica from many commercial sources. Suitable commercially available colloidal silicas include NEXSIL 5, NEXSIL 6, NEXSIL 8, NEXSIL 12, NEXSIL 20, NEXSIL 20A, NEXSIL 20K-30, NEXSIL 20NH4, NYACOL DP9711 (available from Nyacol Nano Technologies, Inc., Ashland, Massachusetts), BENDZIL 2040, LEVASIL 2050, LEVASIL FO1440, MEGASOL S50 (available from Wesbond Corporation, Wilmington, Delaware), NALCO 1050, NALCO 1060, NALCO 1130, NALCO 2326, NALCO 2360 (available from Nalco, Naperville, Illinois), LUDOX SM30, LUDOX HS30, LUDOX AM30, LUDOX PX30, and REMASOL Examples include SP30, REMASOL LP40, and REMASOL LP40 (Remet Corporation, Utica, NY). The size of the colloidal silica may vary from about 5 nm to about 200 nm in some embodiments, from about 5 nm to about 100 nm in other embodiments, and from about 5 nm to about 60 nm in still other embodiments. The sprayable abrasive particle and metal oxide binder slurry may have a solids content of about 5 wt. % to about 60 wt. % in some embodiments, and from about 10 wt. % to about 50 wt. % in other embodiments, based on the weight of the slurry. The metal oxide binder content in the sprayable abrasive mixture may be between about 1 wt. % to about 90 wt. % in some embodiments, and from about 10 wt. % to about 80 wt. % in other embodiments, based on the dry components.

[0070] In some embodiments, the sprayable abrasive slurry mixture composition includes a dispersant and / or a humectant. Dispersants help disperse and stabilize abrasive particles in the slurry. Dispersants are organic, inorganic, or polymeric agents capable of suspending particles in the sprayable slurry. Suitable dispersants include polyvinyl alcohol, polyvinyl butyral, low- to medium-molecular-weight polyvinylpyrrolidinone, cellulose and cellulose derivatives (e.g., carboxymethyl cellulose, hydroxyethyl cellulose, and sodium alginate). Other examples include sucrose, maltose, lactose, low- to medium-molecular-weight polyethylene glycol, and any combination thereof. A humectant may be added to the sprayable slurry to prevent the slurry from drying out too quickly in the nozzle. A humectant is a low-evaporation solvent or a soluble organic or inorganic salt capable of retaining moisture. Exemplary humectants include glycerin, polyols, and polyethylene glycol. In some embodiments, sucrose is used as a dispersant.

[0071] The dispersed sprayable diamond slurry is atomized as droplets in a spray dryer and dried at a temperature of approximately 170°C to form a fine powder. The resulting dried particles are collected in a cyclone. Large particles and agglomerates collected at the bottom of the main drying chamber of the dryer are removed. The inorganic metal oxide binder forms identifiable spherical particles with embedded diamond particles. While the formed beads are identifiable particles, the metal oxide binder and diamond particles do not fuse / sinter at the spray temperature and may break down under certain shear conditions. In some embodiments of the present disclosure, the spray-dried diamond beads exhibit a wide particle size distribution with an average particle size of approximately 12 microns to approximately 25 microns. The average diamond bead size can be adjusted by modifying the spray-drying process parameters and / or the composition of the sprayable slurry. Conventional classification or sieving techniques are used to separate the beads into the desired narrow average particle size and narrow particle size distribution.

[0072] In another embodiment, inorganic metal binders, silica, ceria, titanium dioxide, and alumina, or mixtures thereof, were spray dried in the presence of dispersants and humectants without abrasive particles to form metal oxide beads, such as silica beads. In some embodiments, the silica beads were combined with diamond abrasives to form three-dimensional fixed polishing plates for lapping / polishing silicon carbide wafers.

[0073] In some embodiments, the inorganic metal oxide beads are micron-sized inorganic metal oxide beads having an average particle size of 5 microns to 50 microns, hi some embodiments, the inorganic metal oxide beads are spherical.

[0074] Polymer resins and glassy materials Diamond or other abrasive beads with controlled particle size distributions are used in various formulations to create the fixed abrasive grinding plate 100. The fixed abrasive plate 100 can be fabricated in one piece, as shown in FIG. 4. Larger pieces can be sliced ​​into smaller segments 220 for assembly into fixed abrasive grinding tools 200. For example, the segments 220 can be bonded to a base wheel 210 to create a diamond grinding wheel or other grinding tool for nano-grinding of ceramics and other hard materials. The three-dimensional fixed abrasive plates of the present disclosure may also include, in addition to diamond beads, a polymeric resin or glassy material, fillers and / or fluxing agents, and porosity additives as a composite matrix.

[0075] Suitable polymer resins for embodiments of the present disclosure include Araldite MT35700 epoxy resin, bisphenol A-modified epoxy resins, phenolic resins, polybenzoxazine, bismaleimide, polyetherimide, PEI, polyetheretherketone, PEEK from Huntsman (The Woodlands, Texas), epoxy novolac resins, and their curing agents. Commercially available epoxy resins include DER 330, DER 335, DER 671, DER 640, DEH 84, and DEH 85 from The Dow Chemical Company (Midland, Michigan), Araldite PY 282, 304, GY 280, 253, 505, 502, and EPN 1179 from Huntsman (The Woodlands, Texas), and the EPON resin phenolic epoxy resin series, EPON 825, 828, 862, and 813 from Hexion (Columbus, Ohio). Other suitable polymer resins include unsaturated polyester resins, urea-formaldehyde resins, melamine-formaldehyde resins, base-catalyzed phenolic resins, and acid-catalyzed phenolic resins. Examples of commercially available phenolic resins include BAKELITE PF02245P, DURITE RESIN AD3237, and DURITE RESIN AD5534 manufactured by Hexion, Columbus, Ohio; PLENCO 14043 manufactured by Plastics Engineering Company, Sheboygan, Wisconsin; and VARCUM 29310, 28108, 29318, 29334, 28317, 28101, 29008, 29108, and 29319 manufactured by SBHPP, Novi, Michigan. In some embodiments, suitable polymer resins include powdered phenolic resins and their derivatives. The use of powdered phenolic resins allows for a high volume fraction of diamond beads and fillers. The phenolic resin also provides the high heat resistance and plate hardness necessary for high polishing rates during lapping. In some embodiments, the phenolic resin content in the three-dimensional fixed abrasive formulation is about 5% to about 60% by weight, and in other embodiments, about 5% to about 35% by weight, based on the weight of the polishing plate.

[0076] Some embodiments use phenolic resins, while other embodiments use other common binders such as unsaturated polyesters, epoxies, acrylic polyols, etc. Similar porosity can also be achieved with foamable binders such as polyurethane binders that form a porous network structure.

[0077] The vitreous matrix is ​​generally a continuous material containing silica and one or more other materials or oxides, such as boron trioxide and various metal oxides (e.g., alkali metal oxides and alkaline earth metal oxides). The vitreous matrix can be formed by calcining or thoroughly heating one or more glass frit powders above their melting or softening points. The glass frit powders are typically finely ground to a particle size of approximately 30 to 800 microns (e.g., the width of the particle size distribution). The vitreous bond in the vitreous matrix primarily comprises a metal silicate bond, e.g., an alkali metal aluminoborosilicate bond (i.e., depending on the specific oxides and materials contained in the glass frit powder and fluxing agent). The vitreous matrix binds the abrasive beads and the porous additives in the grinding plate, but is generally not a very homogeneous material. Examples of specific oxides present in the glass frit powder and corresponding vitreous matrix include silica (SiO), lithium oxide (LiO), sodium oxide (NaO), potassium oxide (KO), boron trioxide (BO), aluminum oxide (AlO), calcium oxide (CaO), magnesium oxide (MgO), barium oxide (BaO), zirconium oxide (ZrO), zirconium dioxide (ZrO), titanium dioxide (TiO), zinc oxide (ZnO), calcium difluoride (CaF), manganese dioxide (MnO), and bismuth trioxide (BiO). Silica is typically the major or most abundant individual component in the vitreous matrix or glass frit, for example, present in an amount of at least 20, 30, 40, or 50 wt. % and / or up to 30, 40, 50, 60, 70, or 80 wt. % of the matrix or frit powder. In embodiments, boron trioxide, when present, can be present as a major or minor component, for example, in an amount of at least 2, 3, 5, 8, 10, 14, 20, 30, or 40% by weight, and / or up to 5, 10, 20, 30, 40, 50, or 60% by weight, relative to the matrix or frit powder.Various other metal oxides can be present as minor components, for example, in amounts of at least 2, 3, 5, 8, 10, or 12 wt. % and / or up to 5, 10, 20, or 30 wt. % of the matrix or frit powder, respectively. Some metal oxides can be present in trace amounts, such as 0.001, 0.01, 0.1, 1, 2, 3, or 5 wt. % or less of the matrix or frit powder. Examples of suitable glass frit compositions (w / w) include: (A) 34-41% silica, 13-19% alumina, 25-31% boron trioxide, <2% calcium oxide, 11-16% sodium oxide, and 2-6% potassium oxide; (B) 39-45% silica, 11-15% alumina, 26-31% boron trioxide, 2-5% calcium oxide, and 10-14% magnesium oxide; (C) >20% silica (balance), 5-20% boron trioxide, 5-20% alumina, 5-20% sodium oxide, <5% potassium oxide, and 10-14% magnesium oxide; (D) Silica >20% (balance), Boron Trioxide 5-20%, Sodium Oxide 5-20%, Calcium Oxide 5-20%, Magnesium Oxide <5%, Zirconium Dioxide <5%, Titanium Dioxide <5%, and Bismuth Trioxide <5%, (E) Silica >20%, Boron Trioxide >20%, Alumina 5-20%, Sodium Oxide 5-20%, Potassium Oxide 5-20%, Calcium Oxide 5-20%, and Magnesium Oxide 5-20%. Suitable commercially available glass frit powders are available from Ferro Corporation (Cleveland, Ohio). The specific composition or component distribution of the glass frit can be selected based on the specific grinding plate operation. For example, for abrasive beads (e.g., diamond beads) containing a particular inorganic metal oxide binder, the glass frit can be selected for compatibility and / or adhesion with either or both of the inorganic metal oxide binder and the abrasive itself.For example, a glass frit powder and corresponding vitreous matrix can be selected that contains a substantial amount (e.g., at least 10, 20, 30, or 40 wt. % and / or up to 15, 25, 35, 50, 65, or 80 wt. %) of the same material used as the inorganic metal oxide binder.

[0078] Inorganic fillers and fluxing agents In another embodiment, the three-dimensional fixed abrasive plate includes a filler, such as an inorganic filler. Fillers are inexpensive, non-functional materials used to reduce cost without adversely affecting the lapping plate's performance. Fillers increase the wear rate of the polymer binder, helping to constantly expose new diamond beads. Fillers prevent dulling of the diamonds and maintain consistent cutting action throughout the life of the lapping plate. Suitable fillers include ground precipitated calcium carbonate, talc, kaolin, hydrous aluminum silicate, calcium metasilicate, alumina, clay, or combinations thereof. In some embodiments, ground calcium carbonate is the filler. Examples of calcium carbonate commercially available from Specialty Minerals, Inc., Adams, Massachusetts, include ALBACAR 5970, ALBAGLOS PCC, ALBACAR 8101, and VICRON GCC. The calcium carbonate particle size ranges from about 1 micron to about 30 microns, and the filler concentration ranges from about 1% to about 40% by weight in some embodiments, and from about 5% to about 30% by weight in other embodiments.

[0079] The three-dimensional fixed polishing plate can further include one or more fluxing agents, especially when using a glassy material as the composite material. Fluxing agents are generally known in the art and can be added to reduce or adjust the melting or processing temperature required to transform the original glass frit powder into a continuous glassy matrix. Suitable fluxing agents include clay, kaolin, feldspar (aluminum tectosilicate), borax (hydrated or anhydrous sodium borate), talc, wollastonite (calcium metasilicate), alkali metal nitrates (e.g., lithium nitrate, sodium nitrate, and / or potassium nitrate), alkali metal carbonates (e.g., lithium carbonate, sodium carbonate, and / or potassium carbonate), and combinations or mixtures thereof. In some embodiments, the fluxing agent concentration is about 1% to about 40% by weight, and in other embodiments, about 5% to about 30% by weight. Upon firing, the fluxing agent bonds with the glass frit to form a single glass bond, forming a single (e.g., continuous) matrix material. The fluxing agent is generally a fine powder of any suitable particle size when mixed with the glass frit powder before firing.

[0080] Porous Additives To efficiently remove chips and maintain a constant cutting speed, the 3D fixed abrasive plate is designed with multiple pores within the plate. The pores on the plate surface form discontinuous lapping lands, providing pathways for the lapping lubricant to flow and preventing hydroplaning of the workpiece. The resulting chips flow into the pores, preventing scratches on the workpiece. An embodiment of the present disclosure controls the porosity of the plate surface. Hollow glass spheres are added to the formulation of the 3D fixed abrasive plate to increase and control the porosity of the plate. Examples of commercially available hollow glass spheres applicable to embodiments of the present disclosure include 3M Glass Bubble Series S32, S105, S22, K37, K20, 38HS, and K1 manufactured by 3M Advanced Materials, St. Paul, Minnesota; EXTENDOSPHERE Series TG, SGT, SLG, CG, SG, and TG manufactured by Sphere One, Chattanooga, Tennessee; and SPHERICEL Series hollow glass spheres manufactured by Potters Industries LLC, Valley Forge, Pennsylvania. The amount of hollow glass spheres in the formulation ranges from about 1 to about 50% by weight in some embodiments, and from about 1 to about 40% by weight in other embodiments, and from about 5 to about 30% by weight. The particle size distribution of the hollow glass spheres ranges from about 1 to about 500 microns in some embodiments. EXTENDOSPHERE SG hollow glass spheres are used in some embodiments of the present disclosure.

[0081] The wide particle size distribution of hollow glass spheres results in a variety of pore sizes in the 3D fixed abrasive bead plate. Other pores are caused by the packing structure of the spherical diamond beads. The gaps in the packing structure are partially filled with resin to bind them together. The diamond beads themselves are porous (Figure 1). Because most of the beads have holes and the silica binder is not sintered, the solid mass of beads is porous. Therefore, the beads are prone to brittleness and wear, exposing the diamonds. Some pores are caused by air trapped during mixing and / or curing. The extent of trapped air is controlled by the molding pressure. Excessive molding pressure pushes out the trapped air, reducing the gaps and overall porosity of the plate. The material removal efficiency of the workpiece depends on the total porosity of the plate. A 3D fixed abrasive diamond bead plate with little or no porosity will not produce good polishing results.

[0082] Surface porosity can be analyzed using various techniques. Optical interferometry and stylus profilometry can be used to measure the surface profile (roughness) and calculate the surface porosity. Bulk porosity measurement methods, such as X-ray computed tomography, can also be used to calculate the surface porosity. Gas adsorption and liquid infiltration porosity measurement methods are not suitable because some pores are closed. In embodiments of the present disclosure, three-dimensional optical image analysis was used to quantify the surface porosity. The surface porosity of three-dimensional fixed abrasive bead plates was measured by optical image analysis of high-resolution three-dimensional images of the plates. The percentage of the surface area containing pores is mapped and calculated to determine the porosity of the plate surface at a given magnification, i.e., the surface porosity. Surface porosity (%) is the ratio of the pore area to the total area of ​​the plate. In some embodiments, the minimum surface porosity of a plate to achieve good cutting rates is approximately 3%, while in some embodiments, the porosity is greater than 10%. If the porosity exceeds 60%, the integrity of the plate is compromised, cutting speeds decrease rapidly, and surface finish can be compromised.

[0083] Some embodiments do not function properly if the inorganic metal oxide binder is resistant to wear due to sintering of the diamond beads or if the porosity is significantly reduced. Also, if the diamond beads are porous and therefore easily compressed under pressure, the surface porosity is reduced. Excessive porosity leads to a brittle plate with a high wear rate and a very short life cycle. For best performance, the porosity of the plate surface should range from about 5% to about 60% of the surface area. The diamond beads and plate should be able to withstand water treatment without changing their porosity.

[0084] Example The following examples are illustrative, but not limiting, of the disclosed compositions, articles, and methods.

[0085] Preparation Example 1 - Diamond Polishing Beads 851.9 grams of REMASOL SP30 colloidal silica slurry (commercially available from Remet Corporation, Utica, NY) in a 2-liter glass beaker was mixed with 8.1 grams of sucrose and 140 grams of 1.25 μm single-crystal diamond using a propeller mixer for 20 minutes. The slurry was then dispersed for an additional 20 minutes using an ultrasonic disperser. The resulting slurry was spray-dried using a Yamato ADL311 spray dryer (Yamato Scientific America Inc., Santa Clara, CA) equipped with a #4 nozzle assembly with a 1530 μm orifice. The slurry was stirred at a constant speed before being fed into the inlet tube and flowed into the spray chamber at an inlet temperature of 170 °C. During the spray-drying process, a peristaltic pump was used to transport the slurry into the nozzle chamber. The slurry was atomized as it passed through the orifice by pressurized air into the drying chamber at an inlet temperature of 170 °C. Water was removed from the slurry droplets, separating the particles containing diamond and sucrose in a silica matrix. The separated powder particles were separated by a cyclone and sent to a collection container, while the steam was discharged. Oversized particles and agglomerates collected at the bottom of the drying chamber were discarded as waste. The outlet temperature was approximately 96°C. The diamond slurry prepared according to this recipe yielded 85% diamond beads. Analysis of the beads by scanning electron microscope (SEM) confirmed spherical particles with clear porosity. The average particle size of the beads was 19 μm, as measured with a Beckman Coulter Multisizer 3 Coulter Counter. The collected diamond beads were then classified to an average particle size of 23 μm.

[0086] Preparation Example 2 - Diamond Polishing Beads A 2-liter glass beaker was filled with 630 grams of REMASOL SP30 colloidal silica slurry (REMASOL SP30 is a 30 wt. % 8 nm colloidal silica solution commercially available from Remet Corporation, Utica, NY) and 6.0 grams of sucrose and 103.6 grams of 0.25 μm single-crystal diamond using a propeller mixer for 20 minutes. The mixture was then diluted with 260.4 g of deionized water to produce a diamond slurry. The resulting slurry was dispersed for an additional 60 minutes using an ultrasonic disperser. The resulting slurry was spray-dried using a Yamato ADL311 spray dryer (Yamato Scientific America Inc., Santa Clara, CA) equipped with a #4 nozzle assembly with a 1530 μm orifice. The slurry was stirred at a constant rate before being fed into the inlet tube and flowed into the spray chamber at an inlet temperature of 170 °C. Water was removed from the slurry droplets, separating the particles containing diamond and sucrose in a silica matrix. The separated particles were separated by a cyclone and sent to a collection vessel, and the steam was discharged. Oversized particles and agglomerates collected at the bottom of the drying chamber were discarded as waste. The outlet temperature was approximately 96°C. The diamond slurry prepared according to this recipe yielded 81% diamond beads by weight. Analysis of the beads by scanning electron microscope (SEM) revealed spherical particles with distinct porous characteristics. The average particle size of the beads was 18 μm, as measured with a Beckman Coulter Multisizer 3 Coulter Counter. The collected diamond beads were then classified to an average particle size of 23 μm.

[0087] Preparation Example 3 - Diamond Polishing Beads Diamond beads were prepared by spray drying in the same manner as in Preparation Example 2, except that 0.4 μm single crystal diamond powder was used instead of 0.25 μm single crystal diamond.

[0088] Preparation Example 4 - Diamond Polishing Beads Diamond beads were prepared by spray drying in the same manner as in Preparation Example 2, except that 3 μm single crystal diamond powder was used instead of 0.25 μm single crystal diamond.

[0089] Preparation Example 5 - Diamond Polishing Beads A 2-liter glass beaker was charged with 926.6 grams of NYACOL TiSol A, a 14% solids colloidal titanium dioxide (commercially available from NYACOL Nano Technologies, Inc., Ashland, MA), and 3.3 grams of sucrose and 70 grams of 0.25 μm single-crystal diamonds. The resulting diamond slurry was mixed with the propeller mixer for 20 minutes. The slurry was dispersed for an additional 60 minutes using an ultrasonic disperser. The resulting slurry was spray-dried using a Yamato ADL311 spray dryer (Yamato Scientific America Inc., Santa Clara, CA) equipped with a #3 nozzle assembly with a 711 μm orifice. The slurry was stirred at a constant rate before being fed into the inlet tube and flowed into the spray chamber at an inlet temperature of 170 °C. Water was removed from the slurry droplets, separating the particles, which contained diamond and sucrose within a titania matrix. The separated particles were separated by a cyclone and sent to a collection vessel, while the steam was vented. Oversized particles and agglomerates collected at the bottom of the drying chamber were discarded as waste. The outlet temperature was approximately 84°C. This recipe yielded a diamond slurry containing 78% diamond beads by weight. Analysis of the beads by scanning electron microscope (SEM) revealed spherical particles with distinct porosity. The average particle size of the beads was 14 μm, as measured using a Beckman Coulter Multisizer 3 Coulter Counter.

[0090] Example 1 - Nanogrinding of SiC wafers using a resin-bonded abrasive grinding plate Three-dimensional fixed diamond polishing plate blanks were fabricated by thoroughly mixing all powder ingredients, including 126 g of 250 nm single-crystal diamond-graded diamond beads (Engis Corp., Wheeling, IL), 75.6 g of ARALDITE MT35700 powder resin (Huntsman, The Woodlands, TX), 8.4 g of EPON SU8 epoxy solid resin (Hexion, Columbus, OH), 27.6 g of talc powder, and 27 g of graphite. Additionally, 2.5 g of manganese chloride (Sigma-Aldrich), 6 g of potassium permanganate (Sigma-Aldrich), and 27 g of SPHERICEL 34P30 glass hollow spheres (Potters Industries, LLC, Valley Forge, PA). The powder ingredients were thoroughly mixed in a rotary mixer and then poured into a 7.5 in. (19 cm) square hot press mold. The powder mixture was leveled and flanged to ensure a tight fit. The mold and contents were placed in a preheated 30-ton Wabash 15 in. x 15 in. (38 cm x 38 cm) platen hot press (Wabash MPI, Wabash, Indiana). The mold was heated to 402°F (206°C) and hot pressed at approximately 1060 psi (73 bar) pressure for 10 minutes to form a rigid, three-dimensional fixed-abrasive lapped plate blank. The rigid blank plate was attached to a 12 in. (30.5 cm) square cast iron base plate using double-sided adhesive tape. The plate was flattened on both sides to reduce its thickness to 4.0 mm. The flattened, 4.0 mm thick, rigid blank plate was cut into 20.5 mm x 9.0 mm rectangles to form the abrasive plate segments using known methods, such as rotary cutters, water jet cutters, laser cutters, diamond wire cutters, and electrical discharge machining (EDM). The blank plate was cut using a water jet cutter to create diamond bead plate segments. The diamond bead plate segments were attached to the perimeter / rim of a 12 inch (30.5 cm) diameter base wheel using epoxy adhesive to create the segmented grinding cup wheel shown in Figure 2.The mounted segments are flattened to an even height and the segmented cup wheel is balanced prior to testing.

[0091] The balanced segmented cup wheel was mounted on an EVG300 vertical grinder (Engis Corp., Wheeling, IL) equipped with a ceramic vacuum chuck rotary table. The segmented grinding wheel was positioned at the wheel radius away from the rotary table's axis of rotation. The sample workpiece was a 4-inch (10.2 cm) SiC wafer (4H-SiC). The workpiece was secured in the center of the ceramic vacuum chuck at a pressure less than -0.8 atmospheres (-0.81 bar). During the nanogrinding operation, both the cup wheel and rotary table rotate in the same direction. The grinding cup wheel rotates counterclockwise at 1900 RPM, while the vacuum chuck rotary table rotates in the same direction as the cup wheel at 100 RPM. The initial feed rate of the cup wheel was 0.2 μm / min upon contact with the workpiece and was reduced to 0.05 μm / min at the final 10% setting (μm) of the wheel Z position to achieve better surface finish and flatness. The cup wheel was further dressed using an electroplated diamond dressing (DI-FLEX, manufactured by Engis Corporation) with a 100 / 120 diamond grit size. Deionized water was used as the coolant at a flow rate of 8-9 L / min. The sample material removal rate was calculated from the difference in wafer thickness before and after processing. The wheel wear rate was calculated based on the change in wheel segment height before and after processing and was measured using a Mitsuyo drop gauge indicator. The grinding ratio was determined from the ratio of the sample removal rate to the wheel wear rate. The surface roughness was measured using a Zygo NEWVIEW 6k optical surface roughness tester. The polishing Ra of the 250 nm diamond bead cup wheel plate was 0.84 nm, as shown in Table 1 below.

[0092] Example 2 - Nanogrinding of SiC wafers using a resin-bonded abrasive grinding plate Three-dimensional fixed diamond polishing plate blanks were fabricated by thoroughly mixing all powder ingredients, including 105 g of 500 nm single crystal diamond graded diamond beads, 62.5 g of ARALDITE MT35700 resin (Huntsman, The Woodlands, TX), 22.5 g of EPON SU8 epoxy resin (Hexion, Columbus, OH), 37.5 g of talc, and 22.5 g of SPHERICEL 34P30 glass hollow spheres. The powder ingredients were thoroughly mixed in a rotary mixer and poured into a 7.5-inch square hot press mold. The powder mixture was leveled and secured with flanges. The mold and contents were then placed into a preheated 30-ton Wabash 15-inch x 15-inch (38 cm x 38 cm) platen hot press (Wabash MPI, Wabash, IN). A rigid, three-dimensional fixed-abrasive lapping plate blank was formed by heating the mold to 402°F (206°C) and hot pressing it at approximately 1060 psi (73 bar) pressure for 10 minutes. This rigid blank plate was attached to a 12-inch (30.5 cm) square cast iron base plate using double-sided adhesive tape. The plate was flattened to a thickness of 4.0 mm on both sides using a surface grinder. The 4.0 mm thick flattened rigid blank plate was cut into 20.5 mm x 9.0 mm rectangles to form the grinding plate segments using known methods, such as rotary cutters, water jet cutters, laser cutters, diamond wire cutters, and electrical discharge machining (EDM). The blank plate was then cut using a water jet cutting method to create diamond bead plate segments. The diamond bead plate segments were attached to the perimeter / rim of a 12-inch (30.5 cm) diameter base wheel using epoxy adhesive to create the segmented grinding cup wheel, as shown in Figure 2. The mounted segments are flattened to an even height, and the segmented cup wheel is balanced prior to testing. Following Example 1, the diamond bead cup wheel of Example 2 was performance tested on an EVG-300 vertical grinder manufactured by Engis Corp. of Wheeling, Illinois. The test results are shown in Table 1 below.

[0093] Example 3 - Nanogrinding of the Si surface of a SiC wafer The diamond bead cup wheels of Examples 1 and 2 were used in nanogrinding and compared to a commercially available nanogrinding wheel using the same equipment and tooling. The results are shown in Table 1. As shown in Table 1, the fixed abrasive grinding tool according to the present disclosure provided low surface roughness at various combinations of surface roughness parameters, which are desirable for nanogrinding. Examples 1 and 2 show different grinding plate formulations used to form the cup wheels, and both provided a superior surface finish compared to the comparative example. In other words, while the comparative example exhibited superior material removal rates, it was unable to achieve the desired smooth surface finish useful for nanogrinding. [Table 1]

[0094] Examples 4 to 8: Resin fixed abrasive grinding plates with different hardness Fixed-abrasive grinding plates were prepared using the same procedure as in Examples 1-2, but with different amounts of each component. The Rockwell hardness L scale values ​​of these grinding plates were tested, and the results are shown in Table 2. Table 2 demonstrates that the hardness of the grinding plates can be controlled or selected within a wide range, particularly suitable for nanogrinding. [Table 2]

[0095] Example 9 - Formation of Resin Bonded Abrasive Grinding Segments Generally, the edge / periphery of a molded part is less hard than the interior of the part. Thus, by molding a large blank plate (e.g., a fixed abrasive grinding plate as described herein), smaller segments can be cut from the interior of the blank plate, resulting in grinding plate segments with more uniform hardness values ​​that are used as multiple grinding elements in a corresponding grinding tool.

[0096] For example, as shown in FIG. 4 , a large blank plate 100 measuring 7.5 inches by 7.5 inches by 0.17 inches (19.1 cm by 19.1 cm by 0.43 cm) was formed corresponding to Example 8 above. The blank plate was hardness tested at a series of different sampling locations 1, 2, 3, ..., 8, indicated by "X" symbols in FIG. 4 . The average Rockwell hardness L values ​​at the different sampling locations are shown in FIG. 5 , and show that the hardness is relatively constant at sampling locations 2 through 7 (i.e., the interior of the blank plate 100), while the hardness is significantly lower at sampling locations 1 and 8 (i.e., the edge or periphery of the blank plate 100). Therefore, the inner segments 220 at locations 2 through 7 were cut from the blank plate 100 and used to form the corresponding cup wheels of Example 8. The outer portion of the blank plate 100 (i.e., corresponding to the periphery of approximately 1 cm to 2.5 cm) was not used to form the grinding segments.

[0097] Example 10 - Nanogrinding of SiC wafers using a vitreous fixed abrasive grinding plate A vitreous-bonded diamond polishing plate blank was fabricated by thoroughly mixing all powder ingredients, including 94 g of 500 nm single crystal diamond-classified diamond beads (Engis Corp., Wheeling, IL), 36.8 g of glass frit 90741 powder (Ferro Corp., Cleveland, OH), 9.6 g of feldspar (Laguna Clay Co., Byesville, OH), and 19.2 g of Q-Cel 300 glass hollow spheres (Potters Industries LLC, Valley Forge, PA). The classified diamond beads were prepared similarly to Preparative Example 1 above (silicon dioxide inorganic metal oxide binder), except that 500 nm diamond was used. The particle size of the glass frit powder generally ranged from 30 to 800 microns (i.e., the width of the particle size distribution). The oxide material composition (w / w) was 5-20% boron trioxide, 5-20% alumina, 5-20% sodium oxide, <5% potassium oxide, <5% lithium oxide, <5% calcium oxide, <5% magnesium oxide, <5% zirconium dioxide, <5% titanium dioxide, <5% bismuth trioxide, and >20% silica (the remainder). The powder components were thoroughly mixed in a rotary mixer, and then 32 g of a 10% aqueous gum arabic solution was added and mixed until uniform. The gum arabic was used as an adhesive or binder to hold the powder mixture together in a "green body." The mixture was poured into a 7.5-inch (19 cm) square mold, flattened, and then secured with a flange. The mold and contents were placed in a 30-ton Wabash 15-inch x 15-inch (38 cm x 38 cm) platen hot press (Wabash MPI, Wabash, Indiana). The mold was cold pressed at approximately 500 psi for 1 minute to produce a "green body" plate blank. The "green body" blank plate was allowed to air dry for approximately 24 hours before being fired in a furnace. After drying, the green body plate was fired at 1170°F for 1 hour in a Skutt Automatic kiln, Model GM-1018 (Skutt Ceramic Products, Portland, Oregon) to produce a vitreous bonded abrasive blank plate.The firing process also decomposes, vaporizes, and removes gum and other binder materials from the final blank plate. The vitreous abrasive plate was cut into 20.5 mm x 9.0 mm rectangles using a water jet to create grinding plate segments. The vitreous diamond plate segments were attached to the periphery of a 12-inch (30.5 cm) diameter base wheel using epoxy adhesive to create the segmented grinding cup wheel shown in Figure 2. The attached segments were flattened to the same height, and the segmented cup wheel was balanced prior to testing.

[0098] The segmented vitreous bonded cup wheel was mounted on an EVG300 vertical grinder (Engis Corp, Wheeling, IL) equipped with a ceramic vacuum chuck rotary table. The segmented grinding wheel was positioned one wheel radius away from the rotary table's axis of rotation. The sample workpiece was a 6-inch (15.2 cm) SiC wafer, 4H-SiC, silicon surface. The workpiece was secured in the center of the ceramic vacuum chuck at a pressure below -0.8 atmospheres (-0.81 bar). During the nanogrinding process, both the cup wheel and rotary table rotate in the same direction. The grinding cup wheel rotates counterclockwise at 1325 / 1532 RPM, and the vacuum chuck rotary table rotates at 103 RPM in the same direction as the cup wheel. The initial feed rate of the cup wheel was 0.3 μm / min upon contact with the workpiece, but was reduced to 0.05 μm / min at the final 10% of the wheel Z position (μm) to achieve a better surface finish and flatness. The cup wheel was further finished using a 220-mesh silicon carbide fine pad. Deionized water at a flow rate of 8-9 L / min was used as the coolant. The difference in wafer thickness measurements before and after processing was used to indicate the material removal rate of the sample. The wheel wear rate was calculated based on the change in wheel segment height before and after processing and was measured using a Mitsuyo drop gauge indicator. The ratio of the volume of material removed to the wheel wear volume determines the grinding ratio. The performance of a vitreous abrasive cup wheel is determined by the amount of material removed, the surface finish of the SiC workpiece, measured by surface roughness (Ra), and the amount of physical force consumed. Surface roughness was measured using a Zygo NEWVIEW 6k optical surface roughness tester. Table 3 shows the performance characteristics of vitreous fixed abrasive grinding plates. The material removal rates in Table 3 reflect the total amount / thickness of material removed throughout the grinding process. The wheel load factors (%) in Table 3 are relative to the grinder's maximum current limit (amperes) for wheel spindle rotation, which varies depending on the grinder model. [Table 3]

[0099] As shown in Table 3, the material removal rate remained high and stable from Test 2 to Test 4, demonstrating the self-dressing ability of the vitreous fixed abrasive grinding wheel. The initial decrease in material removal rate in Test 1 was due to a high total thickness variation (TTV). Wheel load (power consumption) is an important factor in grinding wheel performance. In grinding wheel operation, wheel load represents the torque resistance of the spindle. This percentage is expressed as the amperage of the grinding spindle. Typically, a maximum wheel load (%) of less than 40% is desirable. High wheel loads can cause workpiece glare and wafer bowing or distortion. The low maximum wheel load of the vitreous fixed abrasive grinding wheel enables wafer grinding with a consistently low TTV.

[0100] Since other modifications and variations adapted to particular operating requirements and environments will be apparent to those skilled in the art, this disclosure is not to be deemed limited to the examples chosen for illustration, but rather encompasses all modifications and variations that do not depart from the true spirit and scope of the disclosure.

[0101] Accordingly, the foregoing description is for clarity of understanding only, and no unnecessary limitations should be understood therefrom, as modifications within the scope of the present disclosure may be apparent to those skilled in the art.

[0102] All patents, patent applications, government publications, government regulations, and literature cited herein are incorporated by reference in their entirety. In the event of a conflict, the present specification, including definitions, will control.

[0103] Throughout this specification, when a composition, process, kit, or device is described as comprising components, steps, or materials, it is also intended that the composition, process, or device comprise, consist essentially of, or consist of any combination of the described components or materials, unless otherwise specified. Component concentrations may be expressed as weight concentrations unless otherwise specified. Combinations of components are intended to include homogeneous and / or heterogeneous mixtures, as would be understood by one of skill in the art in light of the above disclosure.

Claims

1. A fixed abrasive grinding plate, a) a plurality of micron-sized composite abrasive beads in an amount of 30% to 95% by weight based on the dry weight of the grinding plate; b) at least one porous additive in an amount of 1% to 40% by weight relative to the dry weight of the grinding plate; c) one or more inorganic fillers in an amount of 1% to 40% by weight, based on the dry weight of the grinding plate; d) at least one polymeric resin in an amount of 3% to 40% by weight based on the dry weight of the grinding plate, said polymeric resin binding the abrasive beads; The grinding plate has a hardness value in the range of 20 to 120 on the Rockwell hardness L scale, and the grinding plate has a hardness of 0.8 g / cm ３ ~1.8g / cm ３ Fixed abrasive grinding plates with calculated densities in the range of

2. A fixed abrasive grinding plate, a) a plurality of micron-sized composite abrasive beads in an amount of 30% to 95% by weight based on the dry weight of the grinding plate; b) at least one porous additive in an amount of 1% to 40% by weight relative to the dry weight of the grinding plate; c) one or more fluxing agents in an amount of 1% to 40% by weight based on the dry weight of the grinding plate; d) a vitreous matrix in an amount of 3% to 40% by weight based on the dry weight of the grinding plate, said vitreous matrix binding the abrasive beads together.

3. 3. The fixed abrasive grinding plate of claim 1, wherein the abrasive beads have an average particle size in the range of 5 μm to 50 μm, and each abrasive bead comprises: (i) a plurality of abrasive particles having an average particle size in the range of 10 nm to 10 μm; and (ii) an inorganic metal oxide binder.

4. the abrasive particles are selected from the group consisting of natural diamond, synthetic diamond, cubic boron nitride, silicon carbide, and combinations thereof; the inorganic metal oxide binder is selected from the group consisting of silicon dioxide, titanium dioxide, cerium oxide, zirconium oxide, aluminum oxide, and mixtures thereof; 3. The fixed abrasive grinding plate of claim 1, wherein the abrasive particles are present in an amount of 20% to 90% by weight of the abrasive beads.

5. the weight ratio of (i) polymer resin to (ii) porous additive in the grinding plate is in the range of 1 to 4; 2. The fixed abrasive grinding plate of claim 1, wherein the combined amount of polymer resin and porosity additive in the grinding plate is at least 35% by weight, based on the dry weight of the grinding plate.

6. The weight ratio of (i) the polymer resin to (ii) the total amount of the porous additive and the inorganic filler in the grinding plate is in the range of 0.8 to 1.5; and 2. The fixed abrasive grinding plate of claim 1, wherein the total amount of the polymer resin, the porous additive, and the inorganic filler in the grinding plate is at least 50% by weight, based on the dry weight of the grinding plate.

7. The weight ratio of (i) glassy matrix to (ii) porous additive in the grinding plate is in the range of 1 to 4; and 3. The fixed abrasive grinding plate of claim 2, wherein the combined amount of the vitreous matrix and the porous additive in the grinding plate is at least 30% by weight, based on the dry weight of the grinding plate.

8. The weight ratio of (i) the glassy matrix to (ii) the total amount of the porous additive and the fluxing agent in the grinding plate is in the range of 0.8 to 1.5; and 3. The fixed abrasive grinding plate of claim 2, wherein the total amount of the glassy matrix, the porosity additive, and the fluxing agent in the grinding plate is at least 40% by weight, based on the dry weight of the grinding plate.

9. The surface porosity of the grinding plate is between 5% and 60%, and 3. The fixed abrasive polishing plate of claim 1 or claim 2, wherein the plurality of pores in the grinding plate are not uniform, regular, or interconnected throughout the thickness of the grinding plate.

10. 10. The fixed abrasive grinding plate of claim 1, wherein the polymeric resin is selected from the group consisting of benzoxazine resins, base-catalyzed phenolic resins, acid-catalyzed phenolic resins, epoxy resins, unsaturated polyester resins, and mixtures thereof.

11. The glassy matrix is ​​composed of silica (SiO2) and lithium oxide (Li ２ O), sodium oxide (Na ２ O), potassium oxide (K ２ O), boron trioxide (B ２ O ３ ), aluminum oxide (Al ２ O ３ ), calcium oxide (CaO), magnesium oxide (MgO), barium oxide (BaO), zirconium oxide (ZrO), zirconium dioxide (ZrO ２ ), titanium dioxide (TiO ２ ), zinc oxide (ZnO), calcium difluoride (CaF ２ ), manganese dioxide (MnO ２ ), and bismuth trioxide (Bi ２ O ３ 3. The fixed abrasive grinding plate of claim 2, comprising one or more of:

12. 12. The bonded abrasive grinding plate of claim 11, wherein silica is present in the vitreous matrix in an amount of at least 20% by weight, one or more of sodium oxide, potassium oxide, aluminum oxide, calcium oxide, and barium oxide are individually present in the vitreous matrix in an amount ranging from 3% to 30% by weight, and optionally boron trioxide is present in the vitreous matrix in an amount of at least 3% by weight.

13. The linear thermal expansion coefficient of the glass matrix is ​​20 x 10 －７ / k ~ 200 × 10 －７ / K, the transformation temperature of the glassy matrix is ​​in the range of 400°C to 800°C, and / or the softening temperature of the glassy matrix is ​​in the range of 500°C to 1000°C.

14. The calculated density of the grinding plate is 0.7 g / cm ３ ~1.3 g / cm ３ 3. The fixed abrasive grinding plate of claim 2, wherein the surface roughness is in the range of 0.1 to 1.0 μm.

15. 3. The fixed abrasive grinding plate according to claim 1, wherein the porous additive comprises hollow glass spheres having an average particle size in the range of 10 μm to 200 μm.

16. 2. The fixed abrasive grinding plate of claim 1, wherein the inorganic filler is selected from the group consisting of calcium carbonate, calcium metasilicate, talc, kaolin, calcium oxide, and mixtures thereof.

17. 3. The bonded abrasive grinding plate of claim 2, wherein the fluxing agent is selected from the group consisting of clay, kaolin, feldspar, borax, talc, wollastonite, nitrates of lithium, sodium, and potassium, carbonates of lithium, sodium, and potassium, and combinations thereof.

18. 10. The fixed abrasive grinding plate of claim 1, further comprising at least one of potassium permanganate and potassium periodate.

19. A base plate and 3. A fixed abrasive grinding tool comprising a plurality of fixed abrasive grinding segments attached to the base plate, the fixed abrasive grinding segments comprising the fixed abrasive grinding plate of claim 1 or 2, or a portion thereof.

20. 20. The bonded abrasive grinding tool of claim 19, wherein the bonded abrasive grinding plate comprises at least one polymeric resin.

21. 20. The bonded abrasive grinding tool of claim 19, wherein the bonded abrasive grinding plate comprises a glassy matrix.

22. 20. The bonded abrasive grinding tool of claim 19, wherein the bonded abrasive grinding tool is in the form of a grinding wheel.

23. 20. The bonded abrasive grinding tool of claim 19, wherein the bonded abrasive grinding tool is in the form of a cup wheel.

24. 20. A bonded abrasive grinding kit comprising a plurality of the bonded abrasive grinding tools of claim 19, wherein (i) at least one of the bonded abrasive grinding tools comprises at least one polymeric resin, and (ii) at least one of the bonded abrasive grinding tools comprises a glassy matrix.

25. 20. A method of machining a substrate, comprising performing at least one of grinding and polishing on the substrate with the bonded abrasive grinding tool of claim 19.

26. 26. The method of claim 25, comprising performing nanogrinding on the substrate as the grinding operation.

27. the substrate has an initial surface roughness Ra of at least 30 nm before grinding and / or polishing; the substrate has a final surface roughness Ra of 1 nm or less after at least one of the grinding and polishing is performed; an average material removal rate from the substrate during at least one of the grinding and polishing is 1 μm / min or less; 26. The method of claim 25, wherein the bonded abrasive grinding tool comprises at least one polymeric resin.

28. the substrate has an initial surface roughness Ra of at least 200 nm before being subjected to at least one of grinding and polishing; the substrate has a final surface roughness Ra of 5 nm or less after at least one of the grinding and polishing is performed; an average material removal rate from the substrate during at least one of the grinding and polishing is in the range of 2 μm / min to 10 μm / min; 26. The method of claim 25, wherein the bonded abrasive grinding tool comprises a glassy matrix.

29. 26. The method of claim 25, comprising at least one of grinding and polishing a substrate with a first bonded abrasive grinding tool comprising a glassy matrix, and subsequently at least one of grinding and polishing the substrate with a second bonded abrasive grinding tool comprising at least one polymer resin.

30. 26. The method of claim 25, wherein the substrate is selected from the group consisting of sapphire, titanium carbide reinforced alumina (AITiC), silicon carbide (SiC), gallium nitride (GaN), aluminum nitride (AlN), zinc selenide (ZnSe), silicon wafer, ceramic substrate, optical substrate, and combinations thereof.

31. 1. A method of forming a fixed abrasive grinding segment, comprising: performing at least one of hot pressing, heat-assisted curing, and room temperature curing of a mixture to form a blank plate, the mixture comprising: a) a plurality of micron-sized composite abrasive beads in an amount of 30% to 95% by weight of the mixture; b) at least one porous additive in an amount of 1% to 40% by weight relative to the mixture; c) one or more inorganic fillers in an amount of 1% to 40% by weight of the mixture, and d) at least one uncured polymer resin in an amount of 3% to 40% by weight of the mixture; and A method of cutting the blank plate to form a plurality of bonded abrasive grinding segments, each comprising the bonded abrasive grinding plate of claim 1.

32. 1. A method of forming a fixed abrasive grinding segment, comprising carrying out firing of a mixture to form a blank plate, the mixture comprising: a) a plurality of micron-sized composite abrasive beads in an amount of 30% to 95% by weight of the mixture; b) at least one porous additive in an amount of 1% to 40% by weight relative to the mixture; c) one or more fluxing agents in an amount of 1% to 40% by weight of the mixture; d) a plurality of glass frits in an amount of 3% to 40% by weight of the mixture; e) optionally a binder in an amount of up to 5% by weight of the mixture; and A method for cutting the blank plate to form a plurality of bonded abrasive grinding segments, each comprising the bonded abrasive grinding plate of claim 2.

33. 33. The method of claim 31 or 32, wherein the plurality of fixed abrasive grinding segments are cut from the interior of the blank plate.

34. 34. The method of claim 33, wherein the interior corresponds to an interior surface area in the range of 50% to 80% of the surface area of ​​the blank plate.

35. 33. The method of claim 31 or 32, further comprising bonding a plurality of fixed abrasive grinding segments to a base plate and planarizing the plurality of fixed abrasive grinding segments to a flat condition.

36. hot pressing the mixture in a mold at a temperature ranging from 240°F to 580°F (or about 120°C to 300°C) and a pressure of 200 psi to 2000 psi (or about 13.8 bar to 138 bar); the blank plate has a thickness in the range of 0.1 inch to 1 inch (or about 0.25 cm to 2.5 cm); 32. The method of claim 31, wherein the blank plate has a lateral dimension ranging from 1 inch to 60 inches (or approximately 2.5 cm to 150 cm).

37. cold pressing the mixture in a mold at a temperature ranging from 50°F to 200°F (or about 10°C to 90°C) and a pressure of 300 psi to 1000 psi (or about 20 bar to 70 bar) to form a green part; Optionally, drying the green part to remove any moisture present in the mixture; firing the green part at a temperature of 1000 to 1400 degrees Fahrenheit (or about 540 to 760 degrees Celsius); the blank plate has a thickness of 0.1 inch to 1 inch (or about 0.25 cm to about 2.5 cm); 33. The method of claim 32, wherein the blank plate has a lateral dimension of 1 inch to 20 inches (or about 2.5 cm to about 50 cm).

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