Polyurethane Polishing Pad Dimensional Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional polishing pads made of polyurethane foam experience dimensional instability and reduced polishing performance due to moisture absorption, leading to warping and changes in planarity and in-plane uniformity.
Innovation Solution
A polishing pad with a polyurethane foam layer formed by reacting isocyanate-terminated prepolymers with high and low molecular weight polyols and polyethylene glycol, incorporating chemical crosslinks and a silicone surfactant to enhance cohesion and water affinity, maintaining dimensional stability and improving slurry-holding ability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyurethane foam polishing pad uses polyether or polycarbonate as high molecular polyol component for hydrolysis resistance and elastic properties, then wear resistance and elastic properties are improved, but dimensional stability is reduced when the polishing layer absorbs moisture or water
Solution Approach 1:
The invention changes the molecular weight parameter of the polyol component from conventional high molecular weight (500-1,600 for polyether) to low molecular weight (200-1,000 for polyethylene glycol). This parameter change fundamentally alters the foam structure and crosslinking behavior, enabling the material to achieve both wear resistance and dimensional stability by forming a more cohesive cellular network that resists moisture-induced swelling.
Solution Approach 2:
The invention creates a composite polyurethane foam system by combining polyethylene glycol (low molecular weight polyol) with specific isocyanate prepolymers and crosslinking agents. This composite material approach integrates multiple functional components: the polyethylene glycol provides structural framework and dimensional stability, while the crosslinking agents enhance cohesion and moisture resistance, achieving synergistic performance that neither component could achieve alone.
2Quantity of substance
If the polishing layer absorbs moisture or water, then slurry-holding ability may be improved, but cohesion of hard segment is reduced leading to dimensional instability and warping
Solution Approach 1:
The invention utilizes a porous foam structure generated by the polyethylene glycol-based polyurethane system. The low molecular weight polyol creates a fine-cell porous network that effectively traps and holds slurry within its cellular structure. This porous architecture provides excellent slurry retention while the crosslinked polyurethane matrix maintains dimensional stability even when moisture is absorbed, preventing warping and deformation.
Solution Approach 2:
By changing the polyol molecular weight to low molecular weight (200-1,000) and controlling the foam cell structure, the invention creates an optimized porous network that balances slurry-holding capacity with dimensional stability. The modified parameter set enables the material to absorb and retain slurry effectively while resisting moisture-induced dimensional changes through enhanced crosslinking and cohesive structure.
3Quantity of substance
If a thermoplastic polymer is used to show volume swelling rate of 20% or less in water, then slurry retainability is improved, but high level of dimensional stability when absorbing moisture or water is hardly achieved
Solution Approach 1:
The invention develops a composite polyurethane foam material that integrates the benefits of thermoplastic polymers (slurry retention) with thermosetting characteristics (dimensional stability). The system combines polyethylene glycol-based polyurethane with crosslinking agents to create a composite structure that exhibits both high slurry retainability and superior dimensional stability, overcoming the limitations of conventional thermoplastic polishing pads.
Solution Approach 2:
The invention fundamentally changes the material parameters by using low molecular weight polyol (200-1,000) instead of conventional high molecular weight polyols, and by incorporating crosslinking chemistry. This parameter transformation enables the material to achieve volume swelling rate of 20% or less in water while maintaining high dimensional stability, simultaneously satisfying both slurry retainability and dimensional stability requirements that were previously mutually exclusive.
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 provides a polishing pad with high dimensional stability, enhanced polishing rate, and improved planarization and in-plane uniformity, while maintaining wear resistance and preventing surface scratching.
Implementation Method 1
the polyurethane foam includes a cured product of a reaction of (1) an isocyanate-terminated prepolymer (A) includes an isocyanate monomer, a high molecular weight polyol (a), and a low molecular weight polyol, (2) an isocyanate-terminated prepolymer (B) includes a polymerized diisocyanate and a polyethylene glycol with a number average molecular weight of 200 to 1,000
Implementation Method 2
when the above polishing layer absorbs moisture or water, the cohesion of its hard segment can be reduced so that its dimensional stability can be easily reduced
Implementation Method 3
incorporating chemical crosslinks and a silicone surfactant to enhance cohesion and water affinity
Data Source
AI summary
A polishing pad capable of maintaining a high level of dimensional stability upon moisture absorption or water absorption and providing high polishing rate includes a polishing layer of a polyurethane foam having fine cells, wherein the polyurethane foam includes a cured product of a reaction of (1) an isocyanate-terminated prepolymer (A) that includes an isocyanate monomer, a high molecular weight polyol (a), and a low molecular weight polyol, (2) an isocyanate-terminated prepolymer (B) that includes a polymerized diisocyanate and a polyethylene glycol with a number average molecular weight of 200 to 1,000, and (3) a chain extender.