Polishing Pad Conical Profile for Uniform Wear
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Solution Overview
Problem
Polishing pads develop a stepped profile during use, leading to uneven polishing and edge roll-off of workpieces, which complicates planarization and reduces the flexural strength of chips.
Innovation Solution
A processing method involving a conical chuck table and adjustable polishing pad alignment to maintain even wear across the polishing surface, ensuring the point on the outer circumferential edge of the workpiece is out of contact with the pad at specific coordinates while other points are in contact, preventing a stepped profile formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a polishing pad is used to polish multiple workpieces, then the polishing surface develops a stepped profile, but this causes uneven polishing and edge roll-off of workpieces
Solution Approach 1:
The invention applies a conical profile to the polishing pad, where the polishing surface has a predetermined curvature rather than being flat. This conical shape compensates for the wear that occurs during polishing, maintaining uniform contact pressure across the workpiece surface and preventing the stepped profile that leads to edge roll-off.
Solution Approach 2:
The polishing pad is designed with non-uniform properties across its surface - specifically, a conical profile where the radius of curvature varies from the center to the edge. This local variation in geometry ensures that different regions of the pad wear at appropriate rates to maintain overall planarization quality.
2Adaptability or versatility
If the polishing pad is made pliable to conform to workpiece surface, then it can adapt to surface variations, but it becomes more susceptible to deformation and stepped profile development
Solution Approach 1:
By giving the polishing pad a conical profile with predetermined curvature, the invention provides structural stability that resists deformation during use. The curved geometry distributes stresses more evenly, preventing the pad from deforming into a stepped profile even when the pad material is pliable enough to conform to workpiece variations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method ensures the polishing pad maintains a planarizing capability, preventing edge roll-off and maintaining even wear across the polishing surface, allowing for effective planarization of subsequent workpieces.
Implementation Method 1
the workpiece is polished by rotating a polishing pad made of a resin such as foamed polyurethane or a non-woven fabric such as felt and abrasive grains dispersed in the resin or the non-woven fabric
Data Source
AI summary
A workpiece surface is polished by a polishing pad surface by keeping a point on an outer circumferential edge of the workpiece surface at predetermined coordinates, i.e., first coordinates, in a plane parallel to the workpiece surface but out of contact with the polishing pad surface, and keeping a point on the outer circumferential edge of the polishing pad surface at other coordinates, i.e., third coordinates, in the coordinate plane in contact with an outer circumferential edge of the workpiece surface. In this manner, the workpiece surface is polished in its entirety, and a region of the polishing pad surface in the vicinity of the outer circumferential edge thereof can be worn to the same degree as a region that is located inwardly of the above region. The polishing pad surface is thus prevented from developing a stepped profile due to the polishing of the workpiece surface.