Polishing Pad Hardness and Polymer Composition for Burr Reduction
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Solution Overview
Problem
Polishing pads face challenges in simultaneously reducing burrs at recess corners, maintaining high polishing rate, scratch resistance, and planarization performance, with existing solutions either compromising on these aspects or requiring increased polymer content that alters the polishing layer's characteristics.
Innovation Solution
A polishing pad with a molded polyurethane composition containing 90-99.9% thermoplastic polyurethane and 0.1-10% hygroscopic polymer, specifically 4,4'-diphenylmethane diisocyanate units and polyethylene oxide, providing compatibility and enhanced surface stretchability to prevent burr formation and maintain high polishing rate and scratch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a soft polishing layer is used, then scratch generation is reduced, but local planarization performance and polishing rate deteriorate
Solution Approach 1:
The polishing pad employs a dual-layer structure where the cushioning layer and polishing layer have different hardness values. The cushioning layer (hardness 10-30) provides softness to reduce scratches, while the polishing layer (hardness 40-60) provides hardness for good planarization performance and polishing rate, thus resolving the contradiction through local differentiation of material properties
Solution Approach 2:
The polishing pad combines two different polymer materials with complementary properties: a soft polymer (polyether polyol-based thermoplastic polyurethane) for the cushioning layer to reduce scratches, and a hard polymer (polyester polyol-based thermoplastic polyurethane) for the polishing layer to ensure good planarization and polishing rate, achieving both requirements through material composition
2Manufacturing precision
If a hard polishing layer is used, then local planarization performance is enhanced, but scratch generation increases
Solution Approach 1:
The polishing pad employs a dual-layer structure where the cushioning layer (hardness 10-30) provides softness to reduce scratches, while the polishing layer (hardness 40-60) provides hardness for good planarization performance and polishing rate, thus resolving the contradiction through local differentiation of material properties
Solution Approach 2:
The polishing pad combines two different polymer materials with complementary properties: a soft polymer (polyether polyol-based thermoplastic polyurethane) for the cushioning layer to reduce scratches, and a hard polymer (polyester polyol-based thermoplastic polyurethane) for the polishing layer to ensure good planarization and polishing rate, achieving both requirements through material composition
3Productivity
If recesses are formed in the polishing surface, then slurry supply is improved, but burr generation at corner portions increases
Solution Approach 1:
The polishing pad employs a dual-layer structure where the cushioning layer (hardness 10-30) provides softness to reduce scratches, while the polishing layer (hardness 40-60) provides hardness for good planarization performance and polishing rate, thus resolving the contradiction through local differentiation of material properties
Solution Approach 2:
By controlling the hardness parameter of the polishing layer to be 40-60 (softer than conventional hard layers), the pad reduces burr generation at recess corner portions while maintaining sufficient structural support for effective slurry supply through recesses
4Object-generated harmful factors
If polymer content is increased to reduce burrs, then burr generation is reduced, but polishing layer characteristics are altered
Solution Approach 1:
The polishing pad employs a dual-layer structure where the cushioning layer (hardness 10-30) provides softness to reduce scratches, while the polishing layer (hardness 40-60) provides hardness for good planarization performance and polishing rate, thus resolving the contradiction through local differentiation of material properties
Solution Approach 2:
The polishing pad combines two different polymer materials with complementary properties: a soft polymer (polyether polyol-based thermoplastic polyurethane) for the cushioning layer to reduce scratches, and a hard polymer (polyester polyol-based thermoplastic polyurethane) for the polishing layer to ensure good planarization and polishing rate, achieving both requirements through material composition
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 solution effectively reduces burr generation, maintains high polishing rate and planarization performance, and enhances scratch resistance by ensuring compatibility between thermoplastic polyurethane and hygroscopic polymer, allowing for efficient slurry supply and dressing performance.
Implementation Method 1
a hygroscopic polymer having a moisture absorption rate of 0.1% or more
Implementation Method 2
a polyurethane composition containing 90 to 99.9 mass % of a thermoplastic polyurethane including a non-alicyclic diisocyanate unit
Data Source
AI summary
Disclosed is a polishing pad including a polishing layer that is a molded body of a polyurethane composition, wherein the polyurethane composition contains 90 to 99.9 mass % of a thermoplastic polyurethane including a non-alicyclic diisocyanate unit as an organic diisocyanate unit, and 0.1 to 10 mass % of a hygroscopic polymer, and the molded body has a hardness of 60 or more and less than 75, as measured with a type-D durometer compliant with JIS K 7215.