Non-foamed Polyurethane Polishing Pad Scratch Reduction
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Solution Overview
Problem
Conventional polishing pads face issues with scratches on the surface of objects being polished and inefficient dressing, leading to reduced planarity and polishing rate, as well as short pad life due to uneven surface wear and excessive brittleness.
Innovation Solution
A non-foamed polyurethane polishing pad is developed with a specific composition of isocyanate-terminated prepolymers and a chain extender, which forms a chemically crosslinked network, increasing hardness and brittleness uniformly, thus reducing scratches and improving dressing efficiency while maintaining adequate planarity and in-plane uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a foam polishing pad is used, then the polishing rate is improved, but scratches are likely to occur on the surface of the object to be polished
Solution Approach 1:
The invention changes the fundamental parameter of the polishing pad structure from foamed to non-foamed. This parameter change eliminates the cell structure that causes localized pressure and scratches, while maintaining polishing efficiency through the specific polyurethane composition and chemically crosslinked network that provides optimal hardness and slurry holding characteristics.
Solution Approach 2:
The invention uses a composite material system consisting of specific polyurethane raw materials (isocyanate-terminated prepolymer A, isocyanate-terminated prepolymer B, and chain extender) that form a chemically crosslinked network. This composite material structure provides both the hardness needed for high polishing rate and the uniform surface contact needed to prevent scratches.
2Manufacturing precision
If the polishing pad surface is dressed for a predetermined period, then the planarization performance is restored, but the surface becomes fluffy and uncountable fine uneven portions are produced
Solution Approach 1:
The invention inverts the conventional approach by making the polishing pad surface itself resistant to fluffing during dressing. The chemically crosslinked network structure provides inherent surface stability that prevents the formation of fine uneven portions, eliminating the need for frequent dressing operations and maintaining surface uniformity throughout the pad's service life.
Solution Approach 2:
The invention applies partial dressing action selectively rather than continuous dressing. The enhanced surface durability allows the pad to withstand limited dressing operations without degrading, enabling maintenance of planarization performance without producing excessive surface unevenness.
3Object-affected harmful factors
If a conventional non-foamed polishing pad is used, then scratches are reduced, but the cut rate at the time of dressing is low and dressing takes too much time
Solution Approach 1:
The invention changes the material composition parameters of the non-foamed polyurethane by incorporating specific prepolymers and chain extenders that form a chemically crosslinked network. This parameter change increases the cut rate during dressing by optimizing the balance between hardness and brittleness, reducing dressing time while maintaining the scratch-reducing benefits of the non-foamed structure.
4Manufacturing precision
If the polishing pad hardness is increased to improve planarity, then the planarity is improved, but the pad life decreases due to uneven surface wear and excessive brittleness
Solution Approach 1:
The invention optimizes the hardness parameter through controlled chemical crosslinking of the polyurethane network. This parameter change achieves the desired surface planarity while the crosslinked structure distributes stress more uniformly, preventing uneven wear and excessive brittleness, thereby extending pad life.
Solution Approach 2:
The invention uses a composite polyurethane system with specific raw materials that form a chemically crosslinked network. This composite structure provides both the hardness needed for high planarity and the durability needed for extended pad life by reducing uneven surface wear and preventing excessive brittleness.
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 suppresses scratches, enhances dressing performance, and extends the life of the polishing pad by maintaining a balance between hardness and flexibility, ensuring improved planarity and polishing efficiency.
Implementation Method 1
the non-foamed polyurethane is a reaction cured body of a polyurethane raw material composition containing: an isocyanate-terminated prepolymer A obtained by reacting a prepolymer A raw material composition containing a diisocyanate, a high-molecular-weight polyol (a) and a low-molecular-weight polyol; an isocyanate-terminated prepolymer B obtained by reacting a prepolymer B raw material composition containing an isocyanate-modified body polymerized by adding three or more diisocyanates and a high-molecular-weight polyol (b); and a chain extender
Data Source
AI summary
A polishing pad has a polishing layer including a non-foamed polyurethane, wherein the non-foamed polyurethane is a reaction cured body of a polyurethane raw material composition containing an isocyanate-terminated prepolymer obtained by reacting a prepolymer raw material composition containing a diisocyanate, a high-molecular-weight polyol and a low-molecular-weight polyol; an isocyanate modified body polymerized by adding three or more diisocyanates; and a chain extender, and the addition amount of the isocyanate-modified body is 5 to 30 parts by weight with respect to 100 parts by weight of the isocyanate-terminated prepolymer. The polishing pad hardly causes scratches on the surface of an object to be polished and has an improved dressing property.