Chapter 1: The Performance Cornerstone from the Chemical Field – Understanding PVDF
This chapter aims to explain what PVDF is and why its inherent material properties are so outstanding.
What is PVDF? PVDF is a highly non-reactive thermoplastic fluoropolymer synthesized by the chemical industry through polymerization reactions. The extremely high bond energy of the C-F bond in its molecular structure赋予(gives) the material innate stability.
Core Performance Advantages (Why PVDF?):
Excellent Chemical Inertia: It can withstand corrosion from the vast majority of strong acids, strong alkalis, halogens, and organic solvents. This is unmatched by ordinary stainless steel or even other plastics (like PP, PVC). This characteristic has led to its widespread application in harsh environments within the chemical industry.
Extremely High Purity: The material itself has low leachability, meaning it is不易(unlikely) to release ions and organic contaminants (such as TOC, extractables) into the fluids being conveyed.
Excellent Mechanical Strength and Aging Resistance: Compared to other plastic pipes, PVDF pipes have a higher pressure-bearing capacity, are less prone to deformation, and have a long service life.
Good Flame Retardancy: It is inherently flame-retardant and self-extinguishing when burned, meeting the strict fire safety requirements of semiconductor fabrication plants (fabs).
Chapter 2: The Extreme Demands of Semiconductor Manufacturing – The Challenge of High-Purity Fluids
This chapter focuses on the semiconductor industry, explaining its near-stringent requirements for conveyance systems, thereby introducing why PVDF piping is needed.
What are High-Purity Fluids? In semiconductor manufacturing, this refers to ultra-high purity chemicals and ultrapure water (UPW) used in wet processes such as cleaning, etching, and developing. They have extremely stringent specifications (often measured in ppt or ppb levels) for the content of metal ions (e.g., Na⁺, K⁺, Fe²⁺), particles, bacteria, and Total Organic Carbon (TOC).
Core Challenges for Conveyance Systems:
Contamination Control: The pipe inner wall must be extremely smooth and inert; it absolutely cannot become a source of contamination. Metal pipes may corrode and leach metal ions, while ordinary plastics can leach plasticizers and monomers.
Integrity: The system must be completely sealed to prevent the ingress of external contaminants.
Consistency: The purity of the fluid must be maintained consistently throughout the entire path from the storage tank to the process tool.
Chapter 3: A Perfect Fit – The Application of PVDF Piping in Semiconductor High-Purity Systems
This is the core of the article, detailing how PVDF piping addresses the above challenges and introducing its specific applications.
How Does It Ensure Fluid Purity?
Low Extractables: PVDF itself has very few leachable substances. High-grade PVDF piping that undergoes special treatment and cleaning can better meet industry standards like SEMI F57.
High Smoothness: The inner wall can be processed to be very smooth, making it less likely for particles to adhere and reducing stagnation and bacterial growth.
Excellent Welding Performance: PVDF pipes can be connected using butt fusion welding or socket fusion welding. These connection methods create seamless, additive-free permanent seals, avoiding the leakage and contamination risks associated with using mechanical joints and adhesives. This is a key process for achieving "ultra-high purity" conveyance.
Specific Application Scenarios:
Ultrapure Water (UPW) Distribution Systems: From secondary distribution loops to points-of-use (POU).
Chemical Delivery Systems (CDS): Conveying various high-purity reagents such as Sulfuric Acid (H₂SO₄), Hydrofluoric Acid (HF), Ammonium Hydroxide (NH₄OH), and Hydrogen Peroxide (H₂O₂).
Slurry (CMP Slurry) Delivery: Transporting polishing slurries that require extremely high demands on particle size distribution and stability.
Scrubber Systems: Utilizing its corrosion resistance to handle process exhaust gases.
