Device for the simultaneous double-side grinding of a workpiece in wafer form
View Patent ↗A device for the simultaneous double-side grinding of workpiece wafers has two collinear grinding wheels and two hydropads oppositely positioned for hydrostatic bearing of the workpiece, each having at least one hydrostatic bearing and at least one dynamic pressure tube for measuring the spacing between the workpiece and the hydrdopads. The surfaces of the hydropads which face the workpiece are of nonplanar configuration, contoured in such a manner that the spacing between the surface and the workpiece adopts a minimum value near the edge of the hydropads proximate the grinding wheels, this spacing increasing at increasing distance from the grinding wheels. In a further embodiment, at least one bore, through which liquid and abraded material can be discharged from the vicinity of the dynamic pressure tube, is proximate each dynamic pressure tube.
1. A device for the simultaneous double-side grinding of workpieces in wafer form, comprising two substantially circular grinding wheels arranged collinearly, the grinding surfaces of which are positioned opposite one another in the axial direction based on the axes of rotation of the grinding wheels, and define a midplane located between the grinding wheels, and two devices, likewise positioned opposite each other, for hydrostatically bearing the workpiece in wafer form, each of which comprise at least one hydrostatic bearing and in each case at least one dynamic pressure tube for measuring the spacing between the workpiece and the device for hydrostatic bearing, wherein that surface of each of the two devices for hydrostatic bearing which faces the workpiece is nonplanar, such that the spacing between the surface and the midplane between the grinding wheels has a minimum value proximate that edge of the device for hydrostatic bearing which faces the grinding wheels, and the spacing increases with increasing distance from the grinding wheels.
2. The device of claim 1 , wherein that surface of each of the two devices for hydrostatic bearing which faces the workpiece is conical.
3. The device of claim 1 , wherein that surface of each of the two devices for hydrostatic bearing which faces the workpiece is convex.
4. The device of claim 1 , wherein that surface of each of the two devices for hydrostatic bearing which faces the workpiece is stepped.
5. The device of claim 1 , further comprising at least one bore, through which liquid and any material abraded by grinding can be discharged from the vicinity of the dynamic pressure tube, positioned in the vicinity of each dynamic pressure tube.
6. The device of claim 5 , wherein the bore, at the surface of the device for hydrostatic bearing of the workpiece in wafer form, terminated within a groove which surrounds the dynamic pressure tube in the form of a ring.
7. The device of claim 1 , wherein that surface of each of the two devices for hydrostatic bearing which faces the workpiece, at its edge adjacent to the grinding wheel, does not have any grooves originating from the edge.
8. A device for the simultaneous double-side grinding of a workpiece in wafer form, comprising two substantially circular grinding wheels with collinearly arranged axes of rotation wherein the grinding surfaces of the grinding wheels are positioned opposite one another in axial direction, based on the axes of rotation, and two devices, likewise positioned opposite each other, for hydrostatically bearing the workpiece in wafer form, which each comprise at least one hydrostatic bearing and in each case at least one dynamic pressure tube for measuring the spacing between the workpiece and the device for hydrostatic bearing, wherein at least one bore, through which liquid and any material abraded by grinding can be discharged from the vicinity of the dynamic pressure tube, is arranged in the vicinity of each dynamic pressure tube.
9. The device as claimed in claim 8 , wherein the bore, at the surface of the device for hydrostatic bearing of the workpiece in wafer form, ends in a groove which surrounds the dynamic pressure tube in the form of a ring.
10. A device for the simultaneous double-side grinding of a workpiece in wafer form, comprising two substantially circular grinding wheels with collinearly arranged axes of rotation, wherein the grinding surfaces of the grinding wheels are positioned opposite one another in axial direction, based on the axes of rotation, and two devices, likewise positioned opposite each other, for hydrostatically bearing the workpiece in wafer form, which each comprise at least one hydrostatic bearing and in each case at least one dynamic pressure tube for measuring the spacing between the workpiece and the device for hydrostatic bearing, wherein that surface of each of the two devices for hydrostatic bearing which faces the workpiece, has at least one groove which begins at the edge not facing the grinding wheels, runs in the direction of the edge facing the grinding wheels, before it reaches that edge.