Abrasive disc with vitrified agglomerate islands
An abrasive disc sheet article having patterns of vitrified abrasive particle agglomerate molded islands attached in annular bands on a flexible disc backing is used for high-speed water-spray cooled abrading and polishing without hydroplaning of workpieces. 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 workpiece. Vitrification encapsulates individual abrasive particles in glass to strongly support them to resist abrading forces and to allow them to be progressively worn down for full utilization of expensive diamond particles. Slow eroding of the agglomerates also results in very long abrade life of the abrasive discs. 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 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 thereby forming an abrasive and glass matrix material and wherein the abrasive and glass matrix material is fractured to produce vitrified abrasive agglomerates;
c) wherein a mixture of the vitrified abrasive agglomerates and an island adhesive are mold-formed into abrasive island structures wherein the island 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 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 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 adhesive comprises a solvent-based adhesive or a non-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 the vitrified abrasive agglomerates and the island adhesive is deposited into the mold substrate through holes and wherein the mixture of the vitrified abrasive agglomerates and the island adhesive contacts the backing substrate top surface and wherein the mixture of the vitrified abrasive agglomerates and the island adhesive is level filled with the mold substrate top surface.
9 . The article of claim 8 wherein an agglomerate 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 the vitrified abrasive agglomerates and the island 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 7 wherein the mold substrate through-hole cross-sectional area size ranges from 0.050 inches to 2.0 inches.
12 . 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.
13 . The article of claim 1 wherein the mixture of the vitrified abrasive agglomerates and the island 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.
14 . The article of claim 1 wherein the mixture of the vitrified abrasive agglomerates and the island adhesive is porous wherein the vitrified abrasive agglomerates are structurally supported by the vitrified abrasive agglomerate island adhesive that mutually bonds adjacent abrasive agglomerates and voids exist between adjacent abrasive agglomerates.
15 . 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.
16 . The article of claim 1 wherein the 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.
17 . The article of claim 1 wherein grooves are formed, molded or cut in the porous island gap space erodible material top surface.
18 . The article of claim 1 wherein the backing substrate circular diameter ranges from 1 inch to 144 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 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 to a temperature sufficient to melt the glass frit material thereby encapsulating the abrasive particles in a glass matrix thereby forming an abrasive and glass matrix material, cooling the abrasive and glass matrix material, and fracturing the solidified vitrified abrasive and glass matrix material into vitrified abrasive agglomerates;
c) providing a mixture of the vitrified abrasive agglomerates and an island adhesive and molding the mixture of the vitrified abrasive agglomerates and the island adhesive into abrasive island structures and solidifying the island adhesive wherein the island 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.