Patent Application
20220349488
Embodiments of the present disclosure are directed to fluid handling systems, and more specifically, to operative components used in ultra-pure fluid handling systems with electrostatic discharge mitigation.
Fluid handling systems offering high purity standards have many uses in advanced technology applications. These applications include processing and manufacturing of solar panels, flat panel displays, and in the semiconductor industry for applications such as photolithography, bulk chemical delivery, chemical mechanical polishing (CMP), wet etch, and cleaning. Certain chemicals used in these applications are particularly corrosive, precluding the use of some conventional fluid handling technology because of possible corrosion of the fluid handling components and leaching of chemicals into the environment.
In order to meet the corrosion resistance and purity requirements for such applications, fluid handling systems provide tubing, fittings, valves, and other elements, that are made from inert polymers. These inert polymers may include, but are not limited to, fluoropolymers such as tetrafluoroethylene polymer (PTFE), perfluoroalkoxy alkane polymer (PFA), ethylene and tetrafluoroethylene polymer (ETFE), ethylene, tetrafluoroethylene and hexafluoropropylene polymer (EFEP), and fluorinated ethylene propylene polymer (FEP). In addition to providing a non-corrosive and inert construction, many fluoropolymers, such as PFA, are injectable, moldable and/or extrudable.
Electrostatic discharge (ESD) is an important technical issue for fluid handling systems in the semiconductor industry and in other technology applications. Frictional contact between fluids and surfaces of various operational components (e.g. tubing or piping, valves, fittings, filters, etc.) in the fluid system can result in generation and buildup of static electrical charges. The extent of charge generation depends on various factors including, but not limited to, the nature of the components and the fluid, fluid velocity, fluid viscosity, electrical conductivity of the fluid, pathways to ground, turbulence and shear in liquids, presence of air in the fluid, and surface area. These properties, and ways to mitigate the undesired static electrical charge caused by these properties, are discussed and reported in NFPA 77, “Recommended Practice on Static Electricity”, pp. 77-1 to 77-67, 2014.
Further, as the fluid flows through the system, the charge can be carried downstream in a phenomenon called a streaming charge, where charge may buildup beyond where the charge originated. Sufficient charge accumulations can cause ESD at the tubing or pipe walls, component surfaces, or even onto substrates or wafers at various process steps.
In some applications, semiconductor substrates or wafers are highly sensitive to static electrical charges and such ESD can result in damage or destruction of the substrate or wafer. For example, circuits on the substrate can be destroyed and photoactive compounds can be activated prior to regular exposure due to uncontrolled ESD. Additionally, built up static charge can discharge from within the fluid handling system to the exterior environment, potentially damaging components in the fluid handling system (e.g. tubing or piping, fittings, components, containers, filters, etc.), that may lead to leaks, spills of fluid in the system, and diminished performance of components. In these situations, such discharge, may lead to potential fire or explosion when flammable, toxic and/or corrosive fluids are used in the compromised fluid handling system.
In some fluid handling systems, to reduce the buildup of static charges, certain metal or conductive components in fluid handling system are grounded to mitigate the buildup of static charge in the system as it continually disperses from the metal or conductive components to ground. Conventional use of multiple grounding straps may lead to undue mechanical clutter in a fluid handling system, and may lead to a complex grounding system network requiring extensive maintenance or a complex system that may lead to undesirable contamination, corrosion, or failure of the system.
It would be desirable to improve ESD mitigation in ultra-pure fluid handling systems for improved component performance and reduction in potentially damaging ESD events.
One or more embodiments of this disclosure are related to an operative component for a fluid circuit comprising a housing having i) one or more fluid intake fitting, ii) one or more fluid output fitting, and iii) one or more fluid control component, wherein the fluid control component comprises a conductive fluoropolymer to transfer static charge from the fluid control component to ground. An exemplary embodiment is a valve controlling fluid flow from the intake fitting to the output fitting of the operative component.
In certain embodiments, the operative component comprises a diaphragm valve having a flexible fluoropolymer body to control fluid flow from the intake fitting to the output fitting. In selected embodiments, the flexible fluoropolymer body comprises a conductive fluoropolymer that may be either, for example, an conductive composite fluoropolymer forming the flexible fluoropolymer body being substantially conductive throughout or over all the structure of the flexible body, or a conductive fluoropolymer segment around the perimeter of a non-conductive flexible fluoropolymer body forming a flexible fluoropolymer body with a conductive composite fluoropolymer perimeter segment and a non-conductive fluoropolymer region within this perimeter segment.
Suitable fluoropolymers for the disclosed diaphragm valve include, but are not limited to, perfluoroalkoxy alkane polymer (PFA), ethylene and tetrafluoroethylene polymer (ETFE), ethylene, tetrafluoroethylene and hexafluoropropylene polymer (EFEP), fluorinated ethylene propylene polymer (FEP), tetrafluoroethylene polymer (PTFE), or combinations thereof. In certain embodiments, a suitable polymer for the diaphragm valve comprises tetrafluoroethylene polymer loaded with conductive material. In certain embodiments, these fluoropolymers are loaded with carbon black in ranges of about 0.1-10 wt %, preferably about 1-7 wt %, or more preferably about 3-5 wt %.
In some embodiments, the disclosed diaphragm valve comprises perfluorinated ionomer particles that are blended with a non-conductive fluoropolymer to form a composite including a non-conductive fluoropolymer matrix and regions of perfluorinated ionomer distributed within the non-conductive fluoropolymer matrix. The regions of perfluorinated ionomer within the non-conductive fluoropolymer matrix impart electrostatic dissipative properties to the resultant composite. An example of a suitable perfluorinated ionomer is a perfluorosulfonic acid (PFSA) polymer having a poly(tetrafluoroethylene) backbone with perfluoroether pendant side chains terminated by sulfonic acid groups is commercially available as NAFION™ ionomer (NAFION™ is a trademark of The Chemours Company). Additional examples of commercially available perfluorinated ionomers include, but are not limited to, FLEMION® (Asahi Glass Company), ACIPLEX® (Asahi Kasei), or FUMION® F. (FuMA-Tech) ionomers. Perfluorinated ionomers for use in electrostatic dissipative systems are reported in U.S. Pub. No. US 2020/0103056 A1, the entirety of which is incorporated herein by reference for all purposes.
In other embodiments of this disclosure are related to diaphragm valve for a fluid circuit comprising two or more housing components, one or more intake fitting, one or more output fitting, and a diaphragm; wherein the diaphragm comprises a flexible conductive fluoropolymer body to transfer static charge from the diaphragm to ground. The flexible fluoropolymer body, for example, comprises a conductive fluoropolymer that may be either, for example, a conductive composite fluoropolymer forming the flexible fluoropolymer body being substantially conductive throughout or over all the structure of the flexible body, or a conductive fluoropolymer segment around the perimeter of a non-conductive flexible fluoropolymer body forming a flexible fluoropolymer body with a conductive composite fluoropolymer perimeter segment throughout or overall the structure of the perimeter segment and a non-conductive fluoropolymer region within this perimeter segment.
Suitable fluoropolymers for the disclosed flexible fluoropolymer body of the diaphragm valve include, but are not limited to, perfluoroalkoxy alkane polymer (PFA), ethylene and tetrafluoroethylene polymer (ETFE), ethylene, tetrafluoroethylene and hexafluoropropylene polymer (EFEP), fluorinated ethylene propylene polymer (FEP), tetrafluoroethylene polymer (PTFE), or combinations thereof. In certain embodiments, a suitable polymer for the flexible fluoropolymer body of the diaphragm valve comprises tetrafluoroethylene polymer loaded with conductive material. In some of these embodiments, the flexible conductive body of the diaphragm valve mitigates electrostatic discharge in a flange segment of the diaphragm valve.
Certain embodiments of this disclosure are related to a diaphragm valve for a fluid circuit comprising two or more housing components each having a flange segment, one or more intake fitting, one or more output fitting, a diaphragm, and a gasket; wherein the gasket comprises a conductive fluoropolymer to transfer static charge from the diaphragm valve to ground. In selected embodiments, the diaphragm comprises a flexible fluoropolymer body that is in conductive contact with the gasket.
Suitable fluoropolymers for the disclosed gasket include, but are not limited to, perfluoroalkoxy alkane polymer (PFA), ethylene and tetrafluoroethylene polymer (ETFE), ethylene, tetrafluoroethylene and hexafluoropropylene polymer (EFEP), fluorinated ethylene propylene polymer (FEP), tetrafluoroethylene polymer PTFE), or combinations thereof. In certain embodiments, the gasket comprises tetrafluoroethylene polymer loaded with conductive material. In some of these embodiments, the gasket mitigates electrostatic discharge in a flange segment of the diaphragm valve.
In some embodiments, the disclosed gasket comprises perfluorinated ionomer particles that are blended with a non-conductive fluoropolymer to form a composite including a non-conductive fluoropolymer matrix and regions of perfluorinated ionomer distributed within the non-conductive fluoropolymer matrix. The regions of perfluorinated ionomer within the non-conductive fluoropolymer matrix impart electrostatic dissipative properties to the resultant composite. An example of a suitable perfluorinated ionomer is a perfluorosulfonic acid (PFSA) polymer having a poly(tetrafluoroethylene) backbone with perfluoroether pendant side chains terminated by sulfonic acid groups is commercially available NAFION™ ionomer (NAFION™ is a trademark of The Chemours Company). Additional examples of commercially available perfluorinated ionomers include, but are not limited to, FLEMION® (Asahi Glass Company), ACIPLEX® (Asahi Kasei), or FUMION® F. (FuMA-Tech) ionomers. Perfluorinated ionomers for use in electrostatic dissipative systems are reported in U.S. Pub. No. US 2020/0103056 A1.
One or more embodiments of this disclosure are also related to fluid circuit with integrated electrostatic discharge mitigation comprising a grounded operative component, diaphragm valve, or a gasket of any of the embodiments described above.
Further, One or more embodiments of this disclosure are related to a method of making a fluid circuit with an integrated electrostatic discharge mitigation system comprising installing an operative component, diaphragm valve, or gasket of any of the embodiments described above in the fluid circuit, and grounding the operative component, or diaphragm valve or gasket.
The above summary is not intended to describe each illustrated embodiment or every implementation of the present disclosure.
The drawings included in this disclosure illustrate embodiments of the present disclosure and, along with the description, serve to explain the principles of the disclosure. The drawings are only illustrative of certain embodiments and do not limit the disclosure.
The embodiments of this disclosure are amenable to various modifications and alternative forms, and certain specifies have been shown, for example, in the drawings and will be described in detail. It is understood that the intention is not to limit the disclosure to the particular embodiments described; the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.
This disclosure reports embodiments of an operative component or a diaphragm valve for applications in a fluid handling system with ESD mitigation having a fluid flow passageway from a fluid supply to one or more downstream process stages. Conventional and some ESD mitigation fluid circuits are reported, for example, in International patent application. WO 2017/210293, which is incorporated herein by reference, except for express definitions or patent claims contained therein. Other ESD mitigation fluid circuits are reported, for example, in an Entegris brochure, FLUOROLINE Electrostatic (ESD) Tubing, 2015-2017.
Operative components and diaphragm valves in this disclosure refer to any component or device having a fluid input and a fluid output and that connect with tubing for directing or providing for the flow of fluid. Related and additional components of fluid control systems are illustrated, for example, in U.S. Pat. Nos. 5,672,832; 5,678,435; 5,869,766; 6,412,832; 6,601,879; 6,595,240; 6,612,175; 6,652,008; 6,758,104; 6,789,781; 7,063,304; 7,308,932; 7,383,967; 8,561,855; 8,689,817; and 8,726,935, each of which are incorporated herein by reference, except for express definitions or patent claims contained in the listed documents.
The fluid control components if this disclosure, such as, for example, a diaphragm comprising a fluoropolymer, may be constructed from conductive and/or non-conductive fluoropolymers including, for example, perfluoroalkoxy alkane polymer (PFA), ethylene and tetrafluoroethylene polymer (ETFE), ethylene, tetrafluoroethylene and hexafluoropropylene polymer (EFEP), fluorinated ethylene propylene polymer (FEP), tetrafluoroethylene p[polymer PTFE), or other suitable polymeric materials. For example, in some embodiments the conductive fluoropolymers may be loaded with conductive material (e.g. a loaded fluoropolymer). This loaded fluoropolymer includes, but is not limited to, a fluoropolymer loaded with carbon fiber, nickel coated graphite, carbon fiber, carbon powder, carbon nanotubes, metal particles, and steel fiber.
Alternatively, the fluid control components if this disclosure, such as, for example, a diaphragm may be constructed from perfluorinated ionomer particles that are blended with a non-conductive fluoropolymer to form a composite including a non-conductive fluoropolymer matrix and regions of perfluorinated ionomer distributed within the non-conductive fluoropolymer matrix as described above in this disclosure.
In various embodiments, conductive materials have a resistivity level less than about 1×1010 ohm-m while non-conductive materials have a resistivity level greater than about 1×1010 ohm-m. In certain embodiments, conductive materials have a resistivity level less than about 1×109 ohm-m while non-conductive materials have a resistivity level greater than about 1×109 ohm-m. When the disclosed fluid handling systems are configured for use in ultra-pure fluid handling applications, the fluid control components may be constructed from polymeric materials to satisfy purity and corrosion resistance standards.
The various additional elements of the operative components and diaphragm valves of this disclosure, in addition to the flexible fluoropolymer body described above, may be constructed from materials including metals, polymeric materials, or loaded polymeric materials. Generally loaded polymeric materials of selected structural elements of the operative components and diaphragm valves may include a polymer that is loaded with steel wire, aluminum flakes, nickel coated graphite, carbon fiber, carbon powder, carbon nanotubes, or other conductive material. In some instances, these elements may have a main portion constructed from non-conductive or low conductive material, such as constructed from various hydrocarbon and non-hydrocarbon polymers such as, but are not limited to, polyesters, polycarbonates, polyamides, polyimides, polyurethanes, polyolefins, polystyrenes, polyesters, polycarbonates, polyketones, polyureas, polyvinyl resins, polyacrylates, polymethylacrylates and fluoropolymers. Exemplary fluoropolymers include, but are not limited to, perfluoroalkoxy alkane polymer (PFA), ethylene tetrafluoroethylene polymer (ETFE), ethylene, tetrafluoroethylene and hexafluoropropylene polymer (EFEP), fluorinated ethylene propylene polymer (FEP), and tetrafluoroethylene polymer (PTFE), or other suitable polymeric materials, and having, for example, a secondary co-extruded conductive portion.
The operative components and diaphragm valves of this disclosure are suitable for use in fluid circuits having electrostatic mitigation systems.
The descriptions of the various embodiments of the present disclosure have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
| Number | Date | Country | |
|---|---|---|---|
| 63182503 | Apr 2021 | US |
