Constant-Pressure Valve Structure for Low-Particle PTFE Sealing
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Solution Overview
Problem
In the semiconductor industry, particularly during miniaturization processes, existing constant-pressure valves face challenges in reducing particle generation due to dust contamination, even when using materials like PTFE, which are excellent in chemical resistance and flexibility, but struggle to meet the stringent cleanliness requirements.
Innovation Solution
A constant-pressure valve design featuring a composite material for the shaft and shaft diaphragm, formed by bonding PTFE and cross-linked PTFE, with vertically oriented abutment surfaces and a ring-shaped abutment portion to minimize particle generation, along with a passage-forming body made of cross-linked PTFE for enhanced durability and cleanliness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PTFE is used for the shaft and shaft-side diaphragm, then flexibility and chemical resistance are improved, but particle generation increases
Solution Approach 1:
The shaft is constructed as a composite structure with a PTFE layer bonded to a cross-linked PTFE layer. The PTFE layer provides flexibility and chemical resistance, while the cross-linked PTFE layer reduces particle generation through its enhanced abrasion resistance. This composite material approach resolves the contradiction by combining materials with complementary properties.
2Object-generated harmful factors
If cross-linked PTFE is used throughout the valve, then particle generation is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of using cross-linked PTFE throughout the entire valve, the invention applies it locally only to the shaft and abutment surfaces where particle generation is most problematic. The rest of the valve body continues to use standard PTFE, maintaining chemical resistance and flexibility while reducing overall manufacturing complexity and cost.
3Object-generated harmful factors
If sliding portions are isolated from wetted portions, then cleanliness is improved, but device complexity increases
Solution Approach 1:
The invention uses a diaphragm (a flexible thin film) to isolate the sliding portion from the wetted portion. The diaphragm creates a barrier that prevents dust from the sliding portion from contaminating the chemical liquid in the wetted portion, while maintaining a relatively simple overall valve structure compared to more complex isolation mechanisms.
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 reduces particle generation by using a composite material for the shaft and diaphragm, maintaining outflow pressure constancy despite varying inflow pressures, and ensures high cleanliness and flexibility, significantly improving performance in semiconductor processing.
Implementation Method 1
the valve body-side diaphragm 22 and the shaft-side diaphragm 32 are deformed, thereby constantly maintaining outflow side pressure
Implementation Method 2
Cross-linked PTFE has equivalent chemical resistance and flexibility to PTFE, and has more excellent abrasion resistance than PTFE
Data Source
AI summary
A valve body-side abutment surface 21x which is vertical to moving directions of the valve body 21 and the shaft 31 is formed on the valve body 21, a shaft-side abutment surface 31x which is vertical to the moving directions of the valve body 21 and the shaft 31 is formed on the shaft 31, a valve seat-side abutment surface 41x which is vertical to the moving directions of the valve body 21 and the shaft 31 is formed on the flow rate control passage 13, a valve-closing abutment portion 41y which projects in a ring-shape is formed on the valve body-side abutment surface 21x or the valve seat-side abutment surface 41x, a valve body-pressing abutment portion 31y which projects in a ring-shape is formed on the valve body-side abutment surface 21x or the shaft-side abutment surface 31x, the shaft 31 and the shaft-side diaphragm 32 are formed of composite material which is made by bonding PTFE and cross-linked PTFE to each other, the shaft-side diaphragm 32 is formed of the PTFE, and the shaft-side abutment surface 31x is formed of the cross-linked PTFE.