Ultrapure water (UPW) is essential in the semiconductor industry. UPW is used in wafer production, standard wet cleans, and other wet processes such as some etch processes, solvent processes and chemical mechanical planarization (CMP), and rinses. Contamination such as particles, organic compounds, dissolved ions, and dissolved gases, even at the submicron level, results in damaged or defective product and rapidly escalating fabrication costs. That’s why every component in a UPW or de-ionized water (DI) system must be engineered to maintain the most demanding levels of cleanliness.
Material selection is critical – Teflon® is a good choice because it’s inert and therefore does not contaminate the process. Just as important as the material are the seams within the piping system. Every connection, no matter how it’s made, is a potential source of leaks and particulate or bacterial contamination.
Joints Equal Problems
ChemTec supplies flow switches to a diverse set of industries with varying needs. Every such switch needs connecting to the fluid piping, and within the semiconductor industry there’s a preference for flare fittings.
Flare fittings are commonly either threaded or welded to the flow switch body. Whichever method is employed, there is always a risk of the seam itself allowing contamination of the fluid. Threaded connectors are difficult to clean and welding can produce detritus on internal edges. Turbulent fluid flow will break away microscopic particles which make their way through the system. The rough finish of threaded connectors and welds presents areas where bacteria can take hold and contaminate the process downstream.
With customers in the wafer chip manufacturing industry, ChemTec was well-aware of the problems created by threaded and welded flare fittings, and set to work on a solution. Unlike some competitors, ChemTec produces valve and flow switch bodies in-house, so with full control over machining, and extensive materials expertise, the answer soon became apparent: make the flare fitting an integral part of the flow switch, rather than add-on components.
Making the flare fitting part of the body as opposed to a separate component solved the contamination problem. Precisely machining the complex geometries meant no contamination-inducing rough joints, and no leak paths. As an added bonus, fluid flows more smoothly and the reduced part count simplifies assembly and component management.
Naturally, ChemTec's customers wanted independent verification, so the Teflon® LPH with flare fittings was sent to an independent lab to detect and measure possible contamination problems or introduction of particles. Extensively tested to industry standards over the course of a few years, the Teflon® LPH flow switch with flare fittings exceeded expectations throughout.
Incorporating the flare fitting into a Teflon® flow switch body solved the contamination problem, but there were other benefits too. Fittings and flow switches are usually made from dissimilar materials, creating a risk of corrosion. By using a single material, this problem goes away.
Dissimilar materials usually also come with different coefficients of expansion. For example, temperature changes can create leaks at weak points such as joints but for integral fittings temperature does not create a problem. Additionally, machining and assembly are simplified and offer zero risk of cross-threading the fittings, which is another potential cause of leaks.
The Teflon® LPH flare fitting flow switch was developed to meet the exacting cleanliness standards of the semiconductor industry. Available for liquid flows ranging from 50 to 5,000 ml/m and with ports of ¼”, 3/8” and ½” diameter, it offers benefits wherever cleanliness is a priority.
ChemTec's semiconductor customers have been delighted to remove a potential source of fluid contamination, lowering the risk of product contamination, and helping avoid expensive losses. Similar processing applications handling De-Ionized Water and Ultrapure Water have stringent cleanliness standards and shared concerns for contamination. Pharmaceutical, hospital, biotech, and laboratory and clinical analysis applications will benefit from this Teflon® flare fitting flow switch.