Polyurethane Mounting Pad Pore Uniformity
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Solution Overview
Problem
Existing polyurethane mounting pads have non-uniform internal pore distribution, leading to poor compressibility and compression recovery rates, which limits their application in precise polishing processes for semiconductor and display device substrates.
Innovation Solution
A method involving wet-coagulation of a polyurethane resin with a weight average molecular weight of 220,000 to 1,000,000, followed by immersion in a solution at 40 to 90°C, to form long oval-shaped internal pores with a high aspect ratio, reducing the weight average molecular weight and density of the pad, enhancing compressibility and compression recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional polyurethane mounting pad is used, then it provides basic polishing support, but the internal pores are non-uniform in size and distribution, resulting in poor compressibility and compression recovery rate
Solution Approach 1:
The patent changes the molecular weight parameter of the polyurethane resin to a specific range (220,000 to 1,000,000) and controls the immersion temperature (40 to 90°C) to achieve uniform pore formation and improved compressibility. This parameter optimization resolves the contradiction between pore uniformity and mechanical reliability.
Solution Approach 2:
The patent utilizes the phase transition of the polyurethane resin during wet-coagulation and immersion processes. By controlling the phase change from solution to coagulated state at specific temperatures, uniform pores are formed while maintaining the resin's elastic properties for good compressibility and recovery.
2Manufacturing precision
If the polyurethane resin has high molecular weight to form uniform pores, then pore uniformity improves, but the pad hardness increases and compressibility decreases
Solution Approach 1:
The patent precisely controls the molecular weight parameter within the range of 220,000 to 1,000,000, avoiding both too low (poor pore formation) and too high (excessive hardness) extremes. This optimized parameter range simultaneously achieves uniform pore structure and appropriate softness for compressibility.
Solution Approach 2:
The patent makes the pad properties dynamic by controlling the molecular weight distribution and cross-linking density, allowing the material to exhibit appropriate hardness for structural integrity while maintaining sufficient softness for compression and recovery during polishing operations.
3Reliability
If the mounting pad requires high compressibility for precise polishing, then compression recovery rate improves, but the internal pore structure becomes non-uniform
Solution Approach 1:
The patent optimizes the immersion temperature parameter (40 to 90°C) and residence time to control the degree of coagulation and pore formation. This parameter control ensures that high compressibility is achieved without sacrificing pore uniformity, as the controlled phase transition creates consistent pore structures throughout the pad.
4Ease of operation
If conventional polishing pads are used for glass substrate polishing, then basic polishing function is provided, but waviness control below 20 nm cannot be achieved
Solution Approach 1:
The patent changes the physical parameters of the mounting pad including pore size (50 μm to 2 mm), aspect ratio (3 to 10), and molecular weight, creating a pad with superior uniformity and compressibility characteristics that enable precise waviness control below 20 nm while maintaining ease of polishing operation.
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 method results in a polyurethane mounting pad with uniform, large internal pores, achieving higher compressibility, compression recovery, and elastic modulus, enabling more uniform and precise polishing with improved pressure distribution.
Implementation Method 1
wet-coagulating a resin composition including a polyurethane resin having a weight average molecular weight of 220,000 to 1,000,000 and a DMF solvent
Implementation Method 2
immersing the wet-coagulated material in an immersion solution at 40 to 90°C
Data Source
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AI summary
The present invention relates to a preparation method of a polyurethane mounting pad, including the steps of: wet-coagulating a resin composition including a polyurethane resin having a weight average molecular weight of 220,000 to 1,000,000 and a DMF solvent; and immersing the wet-coagulated material in an immersion solution at 40 to 90°C. According to the preparation method, provided is a polyurethane mounting pad, in which the prepared pad has long and large internal pores uniformly formed to exhibit low hardness, excellent compressibility or the like, and also exhibits more uniform thickness, pressure distribution or tension distribution throughout the whole area thereof, thereby achieving more uniform and precise polishing.