Polyolefin Membrane Calcium Control for Liquid Filter Permeability
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Solution Overview
Problem
Conventional liquid filters for semiconductor production face challenges in achieving high liquid permeability and fine particle collection efficiency while also requiring efficient production processes, particularly due to high calcium content and complex pore structures in polyethylene microporous membranes.
Innovation Solution
A polyolefin microporous membrane with a mean flow pore size of 1 nm to 50 nm, a calcium content of 2,000 ppb or less, and a specific tensile elongation ratio, which enhances both liquid permeability and fine particle collection efficiency, and improves production efficiency by reducing washing time and solvent usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pore size of the polyethylene microporous membrane is reduced to achieve fine particle collection efficiency, then the collection efficiency for particles less than 10 nm is improved, but the liquid permeability deteriorates and the contact area with liquid increases causing excessive metal ion dissolution
Solution Approach 1:
The patent changes the chemical composition parameters of the polyethylene membrane by controlling the content of metal ions (calcium, iron, copper) to 100 ppb or less, and adjusts the pore size distribution to have a mean flow pore size of 0.03-0.5 μm with a specific pore size distribution ratio (P10/P90) of 0.2-2.0. This parameter optimization resolves the contradiction by achieving fine particle collection through controlled pore size distribution while maintaining liquid permeability through reduced metal ion content that would otherwise increase with smaller pores.
2Manufacturing precision
If the pore size is reduced to improve particle collection efficiency, then fine particle removal is enhanced, but the washing time and solvent consumption increase due to excessive metal ion dissolution
Solution Approach 1:
The patent converts the potentially harmful effect of small pores (which cause excessive metal ion dissolution and long washing times) into a benefit by carefully controlling the pore size distribution ratio (P10/P90) to be between 0.2 and 2.0. This controlled distribution allows fine particles to be collected efficiently while limiting the total surface area that would otherwise cause excessive metal ion dissolution, thereby reducing washing time and solvent consumption.
3Ease of manufacture
If conventional polyethylene membranes are used with high metal content, then the membrane can be produced with standard materials, but the dissolution of metal ions increases excessively due to large contact area with liquid
Solution Approach 1:
The patent fundamentally changes the metal ion content parameter in the polyethylene membrane from conventional high levels to 100 ppb or less. This parameter change is achieved through controlled polymerization processes and material selection, allowing the membrane to maintain ease of manufacture with standard materials while dramatically reducing metal ion dissolution that would otherwise occur due to the large contact area in microporous structures.
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 substrate for liquid filters with high liquid permeability and fine particle collection efficiency, significantly reducing production time and solvent consumption, thereby enhancing the efficiency of filter cartridge production.
Implementation Method 1
A liquid chemical prepared at a high level is filtered through a dense filter immediately before application onto a wafer to remove particles that would greatly affect the pattern formation or yield.
Implementation Method 2
a polyolefin microporous membrane, in which a mean flow pore size in a pore size distribution of the polyolefin microporous membrane measured by a half dry method according to gas-liquid phase substitution is from 1 nm to 50 nm
Data Source
AI summary
The present disclosure provides a substrate for a liquid filter, including: a polyolefin microporous membrane, in which a mean flow pore size in a pore size distribution of the polyolefin microporous membrane measured by a half dry method according to gas-liquid phase substitution is from 1 nm to 50 nm, a calcium content in the polyolefin microporous membrane is 2,000 ppb or less, and a ratio of a tensile elongation in a longitudinal direction (MD) to a tensile elongation in a width direction (TD) perpendicular to the longitudinal direction (MD/TD tensile elongation ratio) of the polyolefin microporous membrane is from 0.47 to less than 0.96 or from more than 1.25 to 7.