Sheet in PFA HP 1500x1500 mm natural

A sheet in PFA HP is a high purity class of PFA. HP stands for High Purity, which means the material is produced with strict control over raw materials, process contamination and extractable substances. The sheet you get is optically clear to opaque, has low outgassing and gives off a minimum of ions or particles in contact with process media. The class is made for applications where the smallest contamination can ruin a batch or a measurement.

PFA is a melt processable fluoropolymer that behaves chemically almost identically to PTFE. The material is inert against acids, bases, solvents and oxidizing media, even at high concentrations. The list includes sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, sodium hydroxide, chlorinated solvents and strong oxidizing agents. The service temperature is high, with continuous use around 260 degrees and short peaks around 300 degrees handled without the material breaking down or starting to release particles. At the same time PFA keeps its toughness far down toward cryogenic temperatures, which means the same sheet can be used frozen as well as at high process temperature.

The HP class is made for applications where the smallest contamination is a problem. In the semiconductor industry PFA HP is used as a lining layer in vessels, hoses and piping that carry ultrapure chemicals to wafer processes; a single metal ion from the wrong material can wreck a wafer. In pharmaceutical and biotechnology settings the material works as an inert contact surface against reactants, solutions and biological media, without adding impurities or absorbing components out of the solution. The low outgassing also means the sheet works in vacuum processes and in evacuated vessels without contaminating the atmosphere around it.

Lining plates in vessels for ultrapure acids and bases in semiconductor processes

Partition walls and process plates in cleanrooms

Components in analysis systems and laboratory equipment where contamination would ruin the measurement

Seals and gaskets against ultrapure media in the pharmaceutical industry

Layers in equipment for deionized water and high purity process water

Vacuum chamber lining where low outgassing is required

The surface is smooth, has low friction and is very nearly non-stick. That means the process medium does not take hold and cleaning can be done with strong chemical methods without damaging the sheet. Water uptake is negligible, which guarantees dimensional stability even in condensing or damp environments. Since PFA HP is optically clear to opaque, the surface can be inspected visually for particles and contamination without extra equipment.

In machining, PFA HP behaves like a soft but tough thermoplastic. It can be cut, milled and punched with sharp carbide tools. Use clean oil free cooling or dry machining to keep the risk of contamination down; mineral oil and water based coolants leave traces that take hours to wash off. Thermal welding with hot air or extrusion works well, but the filler rod has to be in the same HP class so it does not introduce contamination in the weld zone. For bolted joints, through bolts with spacer washers work best, since PFA is fairly soft under point load.

The sheet is non-stick from the factory. If it is to be bonded or painted, pretreatment is required, either chemical etching or plasma treatment. Keep in mind that every post treatment potentially lowers the purity class and should be chosen carefully if the HP properties are to be preserved. When installing in a cleanroom, the sheet should be cleaned according to the protocol of the class before installation; even an HP sheet can pick up contamination during transport and handling.

Do you want to know whether PFA HP is the right choice for your process case, or whether a standard PFA is enough? Get in touch and we will go through the purity requirements and the chemical picture together.