CMP Apparatus Curved Polishing Pad Dynamic Speed Control
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Solution Overview
Problem
Conventional lapping and polishing techniques find it difficult to achieve a mirror finish on curved surfaces of workpieces, such as metal or resin bodies, which are commonly used in various electronic and industrial applications.
Innovation Solution
A chemical mechanical polishing apparatus with an annular polishing pad and a rotating workpiece holder, where the workpiece is pressed against an annular polishing surface with a curved vertical cross-section, and the rotational speed of the workpiece is adjusted based on its rotation angle to ensure uniform contact and polishing, utilizing a polishing liquid and a pressing device to achieve a mirror finish.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lapping or polishing techniques are used, then planar surfaces can be polished to a mirror finish, but curved surfaces cannot be polished to a mirror finish
Solution Approach 1:
The polishing pad is designed with a curved vertical cross-section that matches the curvature of the workpiece periphery. This curvature allows the polishing pad to conform to and uniformly contact curved surfaces, enabling mirror finish polishing of workpieces with curved peripheries, which conventional flat polishing techniques cannot achieve.
2Ease of operation
If the workpiece rotates at constant speed, then the polishing process is simple to control, but uniform contact between the curved surface and polishing pad cannot be maintained
Solution Approach 1:
The rotating device varies the rotation speed of the workpiece according to its rotation angle to maintain uniform linear velocity between the workpiece periphery and the polishing pad surface. This dynamic speed adjustment ensures consistent contact pressure and uniform polishing across the entire curved surface, preventing variations in polishing quality that would occur with constant speed rotation.
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 apparatus effectively polishes the curved surfaces of workpieces to a mirror finish by ensuring uniform contact with the annular polishing surface, overcoming the limitations of conventional techniques in achieving high-quality finishes on complex geometries.
Implementation Method 1
the periphery of the workpiece is polished by the sliding contact with the annular polishing surface
Implementation Method 2
a polishing-liquid supply nozzle configured to supply a polishing liquid onto the annular polishing surface
Data Source
AI summary
The present invention relates to a chemical mechanical polishing (CMP) apparatus for polishing a workpiece, such as a metal body, to a mirror finish. The chemical mechanical polishing apparatus includes: a polishing pad (2) having an annular polishing surface (2a) which has a curved vertical cross-section; a workpiece holder (11) for holding a workpiece (W) having a polygonal shape; a rotating device (15) configured to rotate the workpiece holder (11) about an axis of the workpiece (W); a pressing device (14) configured to press a periphery of the workpiece (W) against the annular polishing surface (2a); and an operation controller (25) configured to change a speed at which the rotating device (15) rotates the workpiece (W) according to a rotation angle of the workpiece (W). The pressing device (14) is disposed more inwardly than the workpiece holder (11) in a radial direction of the polishing table (3).