The high-purity standards essential in semiconductor manufacturing require equally pure components in a production environment that meet the highest standards for lack of contamination. The high-purity resins utilized in rotomolding technology create containers for fluid containment that meet goals for mechanical characteristics, chemical resistance, and durability. The rotomolding process and the fluoropolymer resins also often pose an attractive, economical alternative to other methods or materials for fluid containment.
The types of fluoropolymer resins best suited for containers utilized in high-purity applications, such as those in the semiconductor industry, include perfluoroalkoxy (PFA), ethylene tetrafluoroethylene (ETFE), polypropylene, or other parallel resins that exhibit a similar combination of mechanical qualities as well as chemical resistance. Overall, this category of polymers exhibits numerous properties that supply an excellent choice for fluid containment in high-purity applications.
Chemical resistance
Fluoropolymers display a high degree of chemical resistance to a wide range of chemicals, such as acids, bases, and organic solvents. This makes them an excellent choice for use in applications that rely on caustic fluids. While trade secrets protect the exact chemical mixtures and ingredients used in a fab, in general, studies show the “number and volume” of chemicals is increasing, including known carcinogenic substances. In terms of safety, health, and environmental issues, proper containment with the right type of high-purity polymer, which exhibits chemical resistance across a wide spectrum of chemical substances and mixtures, will supply the greatest level of protection.
Mechanical characteristics
A pure resin will ensure that the resulting rotomolded container will supply a known set of mechanical characteristics, in terms of impact resistance, flexural strength, or other desirable features. Pure resin supplies more predictable mechanical characteristics than a mixture or a recycled blend.
Pure resin also will behave in a predictable fashion when subsequent manufacturing processes might be necessary for tank or container completion. For example, dosing bottles or tanks might need sensor channels welded onto the sides. The weld will be more predictable and easier to complete with a pure substrate material.
Dosing bottlesIn addition, semiconductor fabs must be able to rely on a container’s mechanical characteristics when that container is being transported or moved. Rotomolded containers using pure fluoropolymers, which are properly specified for the chemical or fluids they’re designed to contain, pose no risk of breakage or leaks. A rotationally molded tank or container produced from preferred resin beads offers mechanical and corrosion resistance. It also offers a mechanical advantage over other alternative materials, such as steel or quartz glass.
High-purity resin beadsThermal stability
Most fluoropolymers have a high melting point to make them resistant to thermal degradation, or less likely to break down or be damaged when exposed to heat. This stability and lack of degradation are important characteristics in a high-purity manufacturing process.
Each fluoropolymer has temperature range limits — above which the fluoropolymer could release toxic byproducts. The heat resistance, or melting point of a fluoropolymer, is related to its level of crystallinity based on its atomic structure. The lower the crystallinity or any disruption in its atomic structure can lower its melting point, supplying another reason for the sole utilization of pure, virgin polymer resins.
Mixed or recycled resins might form a pocket of material in a container that has a different chemical resistance than the remainder of, or bulk volume of the tank, with a lower melting point. That creates a “hotspot” that can burn out or deteriorate, releasing foreign contaminants into the tank and ruining that stage of processing and product. When selecting the container material, always factor in the highest projected temperature it might encounter during the manufacturing process.
Low permeability, low surface energy
Fluoropolymers have low permeability to gases and liquids, which means they are resistant to the passage of gases and liquids through their chemical structure.
The low surface energy common to fluoropolymers means they are less likely to wet or adhere to other substances, including liquids and chemicals. This property makes containers manufactured from fluoropolymers water repellent, stain resistant, easy to clean, and less likely to retain residue from processing. It allows for complete — or almost total — fluid recovery.
Rotomolding, resin selection help meet production goals
RMB Products only sources its polymer resins from reliable, major manufacturers, such as Asahi, Chemours, Daikin, Dow, and 3M. We can supply material certifications for all the resins utilized in the rotomolding process. In addition, RMB maintains complete traceability from the beginning of the process through shipment.
Rotational molding with RMB provides a quicker timeline for mold delivery, helping projects move from conception through design and into development faster and easier. RMB engineers design a mold and get it ready to begin production of silicon wafers in a matter of weeks (in some cases).
Packaging of high-purity containers in clean roomIn addition, RMB offers a depth of expertise working with PFA, a commonly preferred fluoropolymer in semiconductor manufacturing, that is unmatched by most other molding companies. PFA offers multiple beneficial characteristics for semiconductor applications primarily because of its chemical compatibility. However, it can pose a challenge to mold properly due to its unforgiving mechanical properties. With the help of specially trained and certified technicians, RMB employs a proprietary process to mold PFA daily.
Successful semiconductor manufacturing relies on maintaining a high-purity environment and components that adhere to those same strict standards. Trust RMB and its rotational molding technology for high-purity polymers and quality standards from point of entry through its clean room for packaging and shipping. This can provide the desired combination of chemical resistance, mechanical properties, resistance to contamination, and the durability and serviceability needed now and through the evolving steps and processes involved in chip manufacturing at semiconductor fabrication operations.
Contact us for more information about RMB’s expertise in high-purity resins and rotomolding for the semiconductor industry.
