Abrasive vitrified agglomerate disc with porous islands
An abrasive disc sheet article having annular band patterns of vitrified abrasive particle agglomerate molded islands attached to a flexible disc backing is used for high-speed water-spray cooled abrading and polishing parts. Hydroplaning is prevented as excess coolant water flows around the islands instead of forming a thick water film that separates the island abrasive and the parts. Vitrification encapsulates diamond abrasive particles in glass to strongly support them against abrading forces as the expensive diamond particles are progressively worn down. Solvent-based adhesives are used to mold the islands where evaporation of the solvent results in porous islands that provide controlled rates of island eroding. A porous filler material attached to the disc backing between the island structures carries water to contact the wafer surface and cool it during abrading. Interchangeable discs having different abrasive particle sizes are quickly attached with vacuum to flat rotatable platens.
1 . A vitrified abrasive raised island article comprising:
a) a flexible polymer or metal circular backing substrate having a backing substrate top surface, a backing substrate bottom surface, a backing substrate diameter and a backing substrate thickness;
b) a mixture of abrasive particles and a glass frit material heated to a temperature sufficient to melt the glass frit material thereby encapsulating the abrasive particles in a glass matrix and wherein the abrasive and glass matrix material is cooled to form a solidified vitrified abrasive and glass matrix material and wherein the solidified vitrified abrasive and glass matrix material is fractured to produce vitrified abrasive agglomerates;
c) wherein a mixture of vitrified abrasive agglomerates and an island solvent-based adhesive are mold-formed into abrasive island structures wherein the solvent is evaporated from the island solvent-based adhesive and wherein the solvent-based adhesive is solidified and bonds the abrasive island structures to the backing substrate top surface;
d) wherein the abrasive island structures have abrasive island structure shapes, abrasive island structure sizes, abrasive island structure thicknesses and abrasive island structure flat top surfaces;
e) wherein the abrasive island structures are bonded to the backing substrate top surface in an array pattern band having an array pattern band substantially annular shape, an array pattern band substantially annular outer diameter, an array pattern band substantially annular inner diameter and wherein gap spaces exist between adjacent abrasive island structures;
f) a porous island gap space erodible material that is attached to the backing substrate top surface in the gap spaces between adjacent abrasive island structures wherein the porous island gap space erodible material has a top surface that is level with the abrasive island structures flat top surfaces.
2 . The article of claim 1 wherein the array pattern band substantially annular shape is comprised of island structures arranged in patterns of columns and rows that have an array pattern band substantially annular shape, an array pattern band substantially annular outer diameter, an array pattern band substantially annular inner diameter and wherein the gap spaces exist between adjacent abrasive island structures.
3 . The article of claim 1 wherein the array pattern band substantially annular outer diameter ranges from 70% to 100% of the backing substrate diameter and wherein the array pattern band substantially annular inner diameter ranges from 10% to 90% of the backing substrate diameter.
4 . The article of claim 1 wherein the backing substrate bottom surface is coated with a pressure sensitive adhesive.
5 . The article of claim 1 wherein the island solvent-based adhesive comprises a phenolic or an acrylic solvent-based adhesive.
6 . The article of claim 1 wherein the mold-formed abrasive island structures are bonded to the backing substrate top surface using a mold substrate having a mold substrate material, a mold substrate top surface, a mold substrate bottom surface, a mold substrate size, a mold substrate shape, a mold substrate thickness and a pattern of selectively spaced mold substrate through-holes that extend through the mold substrate thickness.
7 . The article of claim 6 wherein the mold substrate through-holes have a mold substrate through-hole shape, a mold substrate through-hole cross-sectional area and a mold substrate through-hole cross-sectional area size.
8 . The article of claim 7 wherein the mold substrate bottom surface is positioned in flat surfaced conformal contact with the backing substrate top surface, wherein the mixture of vitrified abrasive agglomerates and the island solvent-based adhesive is deposited into the mold substrate through holes and wherein the mixture of vitrified abrasive agglomerates and the island adhesive contacts the backing substrate top surface and wherein the mixture of vitrified abrasive agglomerates and the island adhesive is level filled with the mold substrate top surface.
9 . The article of claim 8 wherein a binding adhesive is deposited into the mold substrate through holes and coats the backing substrate top surface at the locations of the mold substrate through holes before the mixture of vitrified abrasive agglomerates and the island solvent-based adhesive is deposited into the mold substrate through holes.
10 . The article of claim 8 wherein a binding adhesive is deposited on the backing substrate top surface and coats the backing substrate top surface before the mold substrate bottom surface is positioned in flat surfaced conformal contact with the backing substrate top surface.
11 . The article of claim 1 wherein the abrasive particles have selected sizes and the abrasive particles are selected from the group consisting of diamond, silicon carbide, boron carbide, cubic boron nitride, aluminum oxide, ceria, silica and combinations thereof.
12 . The article of claim 1 wherein the mixture of vitrified abrasive agglomerates and the island solvent-based adhesive also has an abrasive agglomerate erodible filler wherein the abrasive agglomerate erodible filler comprises erodible fillers selected from the group consisting of walnut shell particles, hollow glass beads, hollow polymer beads, organic material particles, foamed glass beads and combinations thereof.
13 . The article of claim 1 wherein the mixture of vitrified abrasive agglomerates and the island solvent-based adhesive is porous wherein the vitrified abrasive agglomerates are structurally supported by the vitrified abrasive agglomerate island solvent-based adhesive that mutually bonds adjacent abrasive agglomerates and voids exist between adjacent abrasive agglomerates.
14 . The article of claim 1 wherein the porous island gap space erodible material is a polymer foam material that is attached to the backing substrate top surface in the gap spaces between adjacent abrasive island structures wherein the porous island gap space erodible material has a top surface that is level with the abrasive island structures flat top surfaces.
15 . The article of claim 1 wherein porous island gap space erodible material is constructed from erodible material particles or beads selected from the group consisting of walnut shell particles, hollow glass beads, solid polymer beads, hollow polymer beads, organic material particles, foamed glass beads and combinations thereof wherein the selected erodible material particles or beads are coated with an adhesive, mixed together and deposited on the backing substrate top surface in the gap spaces between adjacent abrasive island structures wherein the erodible material particles or beads contact adjacent erodible material particles or beads wherein the adjacent selected erodible material particles or beads are bonded together at their mutual adhesive coated contact points leaving voids between the adjacent selected erodible material particles or beads to form the porous island gap space erodible material.
16 . The article of claim 1 wherein grooves are formed, molded or cut in the porous island gap space erodible material top surface.
17 . The article of claim 1 wherein the backing substrate circular diameter ranges from 1 inch to 144 inches.
18 . The article of claim 7 wherein the mold substrate through-hole cross-sectional area size ranges from 0.050 inches to 2.0 inches.
19 . The article of claim 1 wherein the glass frit material is a synthetic glass frit material.
20 . A process for using vitrified abrasive materials to produce abrasive island discs comprising:
a) providing a flexible polymer or metal circular backing substrate having a backing substrate top surface, a backing substrate bottom surface, a backing substrate diameter and a backing substrate thickness;
b) providing a mixture of abrasive particles and a glass frit material and heating the mixture of abrasive particles and glass frit material to a temperature sufficient to melt the glass frit material thereby encapsulating the abrasive particles in a glass matrix and cooling the abrasive and glass matrix material to form a solidified vitrified abrasive and glass matrix material and fracturing the solidified vitrified abrasive and glass matrix material into vitrified abrasive agglomerates;
c) providing a mixture of vitrified abrasive agglomerates and an island solvent-based adhesive and molding the mixture of vitrified abrasive agglomerates and the island solvent-based adhesive into abrasive island structures and solidifying the island solvent-based adhesive wherein the island solvent-based adhesive bonds the abrasive island structures to the backing substrate top surface;
d) forming the abrasive island structures to have abrasive island structure shapes, abrasive island structure sizes, abrasive island structure thicknesses and abrasive island structure flat top surfaces;
e) bonding the abrasive island structures to the backing substrate in an array pattern band having an array pattern band substantially annular shape, an array pattern band substantially annular outer diameter, an array pattern band substantially annular inner diameter and wherein gap spaces exist between adjacent abrasive island structures;
f) providing a porous island gap space erodible material that is attached to the backing substrate top surface in the gap spaces between adjacent abrasive island structures wherein the porous island gap space erodible material has a top surface that is level with the abrasive island structures flat top surfaces.