UV-Cured Elastomer Film Thickness and Oxygen Inhibition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
UV-cured polyurethane elastomers used in CMP pads face issues with high viscosity, making handling difficult, and suffer from oxygen inhibition, resulting in uncured material on the surface unless cured in an inert atmosphere or covered, which complicates processing.
Innovation Solution
A method involving applying an actinic radiation-curable composition to a substrate, exposing it to actinic radiation to produce a cured elastomeric film, and removing it, without needing oxygen inhibition mitigation techniques, using a composition comprising urethane (meth)acrylate polymers, allophanate urethane (meth)acrylate polymers, and lactone-containing (meth)acrylate polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UV curable polyurethane materials are used for CMP pads, then the pads can be produced with good elastomeric properties, but the uncured compositions have very high viscosities (10,000-200,000 cps) which lead to difficulties in handling and processing
Solution Approach 1:
The patent modifies the chemical composition parameters by incorporating specific urethane (meth)acrylate polymers with controlled molecular weights and functionalities, along with reactive diluents, to achieve an optimal balance between viscosity and cured elastomeric properties. This allows the composition to be processed more easily while maintaining reliable elastomeric performance after curing.
2Productivity
If UV curing is used to cure the elastomer, then the curing process is fast and efficient, but oxygen inhibition occurs during UV curing which leads to uncured material on the outer surface of the pads
Solution Approach 1:
The patent employs a composite photoinitiator system combining multiple photoinitiators with different absorption characteristics and reactivity profiles. This composite approach enables deep and uniform curing through the thick composition while maintaining surface curing quality, overcoming the oxygen inhibition problem that typically affects surface layers during UV curing.
Solution Approach 2:
The patent uses a dual-wavelength UV curing approach that effectively 'copies' the curing action at different depths - using one wavelength for surface curing and another for deep penetration curing, ensuring complete curing throughout the thickness without surface defects.
3Manufacturing precision
If oxygen inhibition mitigation techniques such as inert atmosphere or cover placement are used, then surface curing is improved, but the process complexity and equipment requirements increase
Solution Approach 1:
The patent formulates the composition with oxygen-scavenging components and optimized photoinitiator systems that automatically counteract oxygen inhibition during the curing process itself, without requiring external inert atmosphere equipment or cover placement. The composition self-regulates the curing environment to prevent surface defects.
4Duration of action of stationary object
If high thickness elastomers (at least 10 mils) are produced, then the pad durability and performance are improved, but complete curing becomes more difficult due to UV penetration limitations
Solution Approach 1:
The patent employs a multi-stage UV curing process with periodic exposure at different wavelengths and intensities. This allows the UV energy to penetrate and cure the thick composition (at least 10 mils) completely, ensuring both pad durability and full curing throughout the thickness by delivering energy in controlled periodic cycles.
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 produces high thickness elastomers with minimal uncured surface residue, eliminating the need for oxygen inhibition mitigation techniques and improving processing ease by ensuring complete curing without surface uncured material.
Implementation Method 1
exposing the composition to actinic radiation to produce a cured elastomeric film
Data Source
AI summary
Methods of producing an elastomer are disclosed that include (I) applying an actinic radiation curable composition preferably selected from a urethane (meth)acrylate, an allophanate urethane (meth)acrylate or a lactone-containing (meth)acrylate to a substrate at a thickness of at least 0.25 mm (10 mils); (II) exposing the composition ultraviolet radiation to produce a cured film; and (III) removing the film from the substrate. Related compositions are also disclosed.