Upper Turn Table Stability in Double-Side Polishing
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Solution Overview
Problem
The upper turn table in double-side polishing and lapping apparatuses is unstable in tilt when stopped at intermediate height due to movable universal joints or spherical bearings, leading to non-uniform cleaning and dressing of polishing surfaces, resulting in fluctuating wafer quality.
Innovation Solution
A workpiece processing apparatus featuring a center drum with first and second grooves, where hooks on the upper turn table engage with the grooves to maintain horizontal stability under vertical forces, allowing uniform cleaning and dressing of polishing pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If movable universal joints or spherical bearings are used to connect the upper turn table, then the upper turn table can change angle optionally to accommodate thickness variation, but the upper turn table becomes unstable in tilt when stopped at intermediate height
Solution Approach 1:
The connection mechanism is segmented into multiple functional components: the universal joint/spherical bearing for angle adjustment, the support surface for positional stabilization, and the groove structure for constrained movement. This segmentation allows each component to perform its specific function without interfering with others, resolving the contradiction between adaptability and stability.
Solution Approach 2:
The support surface is positioned in advance at a specific location within the groove to provide preliminary stabilization before the upper turn table reaches the intermediate height stopping position. This preliminary action ensures that when the turn table stops, it is already supported and stabilized, preventing tilt instability.
2Adaptability or versatility
If the upper turn table is made unstable in tilt at intermediate height, then angle adjustment is flexible, but cleaning and dressing of polishing surfaces becomes non-uniform
Solution Approach 1:
Instead of allowing the upper turn table to be freely unstable and then trying to achieve uniformity through other means, the invention inverts the approach by providing a fixed support surface that actively maintains horizontal stability. This inverted approach ensures uniformity is achieved through positive stabilization rather than negative tolerance.
3Ease of operation
If the upper turn table tilts when stopped at intermediate height, then movement freedom is maintained, but the gap between upper and lower turn tables becomes non-uniform
Solution Approach 1:
The support surface acts as an intermediary element between the upper turn table and the lower turn table. It mediates the relationship by providing a stable reference plane that ensures uniform gap maintenance during cleaning and dressing operations, while still allowing the upper turn table to move freely when not supported.
Data Source
AI summary
A workpiece processing apparatus including: a center drum that is rotatable around a rotation axis and has at least one first groove formed in the axial direction on the peripheral surface, a carrier having a holding hole to insert and hold a workpiece to be processed, an upper and lower turn table that are rotatable around the rotation axis in a state wherein the carrier holding workpiece is interposed, at least one hook fitted in the upper turn table's internal circumference, with the tip being inserted into the first groove and movable along first groove; wherein the center drum has at least one second groove formed in the axial direction on peripheral surface, and second groove has a length different from that of the first groove and has a supporting surface to support the hook from below at a position above a position where upper turn table processes the workpiece.