US20190091617A1

US20190091617A1 - Conductive filter device

Info

Publication number: US20190091617A1
Application number: US16/300,410
Authority: US
Inventors: Jad Ali Jaber; Yasuji Suzuki
Original assignee: Entegris Inc
Current assignee: Entegris Inc
Priority date: 2016-06-01
Filing date: 2017-05-31
Publication date: 2019-03-28
Also published as: TW201805053A; US20220307634A1; JP6750043B2; TWI644712B; US20190145560A1; CN109195682A; US12117106B2; WO2017210293A1; KR20190012202A; WO2017210291A2; JP2019523848A; JP2019520197A; CN109312883A; US11384879B2; DE112017002800T5; DE112017002783T5; TWI645889B; WO2017210291A3; KR20190014545A; CN109312883B

Abstract

A pleated filter including a porous fluoropolymer filter membrane and a supporting net positioned directly adjacent to the filter membrane. In various embodiments the supporting net is placed on at least one of an outflow side of the filter membrane and an inflow side of the filter membrane. In one or more embodiments, the supporting net includes a mesh of non-conductive fluoropolymer threads and conductive fluoropolymer threads. The conductive fluoropolymer threads in certain embodiments extend substantially parallel to pleats of the filter membrane and the supporting net.

Description

RELATED APPLICATION

The benefit of priority under 35 U.S. C. § 119 of U.S. Provisional Patent Application No. 62/344,168, filed 1 Jun. 2016, and U.S. Provisional Patent Application No. 62/344,171, filed 1 Jun. 2016, is hereby claimed. The disclosure of U.S. Provisional Patent Application No. 62/344,168 is incorporated herein by reference, in its entirety, for all purposes. This application is related to the application entitled FLUID CIRCUIT WITH INTEGRATED ELECTROSTATIC DISCHARGE MITIGATION, U.S. Provisional Patent Application No. 62/344,171, filed 1 Jun. 2016, owned by the owner of the instant application and filed on the same day as the instant application, and which is incorporated herein by reference in its entirety, except for express definitions or patent claims contained therein.

TECHNICAL FIELD

Embodiments of the present disclosure relate to fluid handling systems, and more specifically, to conductive filters in a fluid circuit for electrostatic discharge mitigation.

BACKGROUND

Fluid handling systems offering high purity standards have many uses in advanced technology applications. These applications include processing and manufacturing of solar panels, hard disk drives, flat panel displays, and in the semiconductor industry for applications such as photolithography, bulk chemical delivery, and chemical mechanical polishing, wet etch, and cleaning. Furthermore, certain chemicals used in these applications are particularly aggressive, precluding the use of some conventional fluid handling technology due to possible incompatibility 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 include, but are not limited to, fluoropolymers such as, polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), ethylene tetrafluoroethylene (ETFE), and fluorinated ethylene propylene (FEP). In addition to providing a chemically compatible and inert construction, many fluoropolymers, such as PFA, are injection moldable and extrudable.
Additionally, chemical liquids such as concentrated aqueous acids, bases and organic solvents are used in the manufacture of semiconductors and microelectronic devices. To prevent circuit failure, chemical liquids must be purified before use to remove contaminates and also must be purified during use to remove particles generated from the wafer etching process.
The industry standard for purification of chemical liquids is by filtration through a cartridge comprising a porous polymeric membrane with a morphology optimized to remove contaminants such as particles or microorganisms from the liquids.
Since chemical liquids can be corrosive fluids or organic solvents that can swell or dissolve polyolefin membranes, chemically inert membranes that can resist chemical degradation such as fluoropolymer membranes like PTFE are preferentially used. However, PTFE membranes are characterized by low surface energy and the aqueous based liquids and some organic solvents do not adequately wet the membrane surface. Even if the PTFE membrane is pre-wet with organic solvents such as alcohols before filtering the chemical liquids, the membrane would still de-wet during use because of the thermodynamic in-compatibility between an aqueous based fluid and a hydrophobic membrane surface. Inadequate wetting or de-wetting during use leads to undesirable low membrane flux and high pressure drop across the membrane.
Several attempts have been made to render fluoropolymer membranes more compatible with aqueous based liquids. For example, see U.S. Pat. No. 6,179,132 and U.S. Patent Pub. No. 2010/0018925, each of which are incorporated herein by reference, except for express definitions or patent claims contained therein.
Electrostatic discharge (ESD) is another known issue for fluid handling systems in the semiconductor industry and in other technology applications. Frictional contact between fluid and surfaces of various operational components (e.g. piping, valves, fittings, filters, etc.) in the fluid system can result in generation of and buildup of static electrical charges. For example, during filtration operations, electric charges can develop on membrane surface. 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, fluid conductivity, pathways to ground, turbulence and shear in liquids, presence of free air in the liquid, and surface area. Furthermore, as the fluid flows through the system, the charge can be carried downstream in a phenomenon called a streaming charge, where charge can buildup beyond where the charge originated. Sufficient charge accumulations can cause discharges at the pipe walls, component surfaces, or even onto substrates or wafers at various process steps.
Substrates are highly sensitive and such discharge can result in damage or destruction of the substrate. For example, circuits on the substrate can be destroyed and photoactive compounds can be activated prior to regular exposure. Additionally, built up static charge can discharge from within the fluid handling system to the exterior environment, potentially damaging components in the plumbing (e.g. tubing, fittings, containers, filters, etc.), and leading to leaks, spills of fluid in the system, and diminished performance of components.
In some fluid handling systems, to reduce the buildup of static charges, certain components in fluid handling system are constructed are grounded to mitigates the buildup of static in the system as it continually disperses from the metal conductive components to ground.
For example, FIG. 1 depicts a fluid handling system 100 of the prior art. The system 100 provides a flow path for fluid to flow from a fluid supply 104 to one or more process stages 108 positioned downstream. As used herein, process stage 108 refers to a point of use for fluid in the system 100, or any intermediate point in the fluid handling system 100 where the fluid is utilized in a method or process. System 100 includes a fluid circuit 112 including a portion of the flow path from the fluid supply 104 to the one or more process stages 108. The fluid circuit 112 includes tubing segments 116 and a plurality of interconnected operative components 118 such as elbow shaped fitting 120, T-shaped fitting 122, a valve 124, filters 126 and flow sensor 128.
As used herein, tubing 116 refers to any flexible or inflexible pipe or tube that is suitable for containing or transporting fluid therethrough. Operative components refers to any component or device having a fluid input and a fluid output and that is mateable with tubing for directing or providing for the flow of fluid. Examples of operative components include, but are not limited to, fittings, valves, filters, pumps, mixers, spray nozzles, and dispense heads. These and additional non-limiting examples of operative components are illustrated by 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 therein.
Tubing segments 116 are conductive, providing an electrical pathway along the length of each tubing segment 116 in the fluid circuit 112. Conductive tubing is primarily constructed from materials including metal or loaded polymeric material. Loaded polymeric material includes 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, the tubing segments 116 are partially conductive, having a main portion constructed from non-conductive or low conductive material, such as perfluoroalkoxy alkane (PFA), or other suitable polymeric materials, and having a secondary unitary co-extruded conductive portion.
For example, fluid circuit 112, in certain instances, can utilize FLUOROLINE®, PFA tubing, available from Entegris Inc., the owner of this application. FLUOROLINE®, PFA tubing is primarily constructed from PFA with one or more conductive strips of carbon loaded polymer that is extruded along the length of the tubing at its exterior surface. A circuit diagram 132 is superimposed over the fluid circuit 112 that illustrates the electrical pathways provided by the conductive or partially conductive tubing segments 116.
Continuing to refer to Prior Art FIG. 1, in contrast to the tubing segments 116, the operative components 118 are each constructed primarily from non-conductive materials. For example, the operative components can be constructed from fluoropolymers including perfluoroalkoxy alkane (PFA), ethylene tetrafluoroethylene (ETFE), and fluorinated ethylene propylene (FEP), polytetrafluoroethylene (PTFE), and perfluoroalkoxy alkane (PFA). This occurs, for example, when system 100 is configured for use in ultra-pure fluid handling applications, where the tubing segments 116 and operational components 118 are typically constructed from polymeric materials to satisfy purity and corrosion resistance standards.
To mitigate static charge buildup, the tubing segments 116 may be electrically connected to ground 140 at various points in the fluid circuit 112 via some of the conductive straps 136. The conductive straps 136 disperse charge from the conductive strips running the length of the tubing 116 to ground 140. Additionally, sections of the tubing segments 116 may be electrically tied together via conductive straps 136 that bridge the electrical pathway across each of the non-conductive operative components 118. The conductive straps 136 are tied to the exterior of one or more of the tubing segments 116 and form an electrical connection with the conductive strips that run the length of each segment.
However, it would be desirable to improve static charge mitigation in ultra-pure fluid handling systems for improved component performance and reduction in potentially damaging ESD events.

SUMMARY

Referring back to prior art FIG. 1, the non-conductive fittings 120, 122, valve 124, filters 126 and sensor 128 electrically isolate segments of the fluid circuit 112 by causing breaks in conductivity between tubing segments 116. Consequently, while tubing segments 116 are grounded, static charge still builds within each of the non-conductive operative components 118. For example, in an ultra-pure fluid handling system, a differential measured from the exterior of a PTFE fitting can reach nearly 30,000 volts. Similarly, in the filters 126, fluid friction from fluid passing through a filter membrane can cause a measurable voltage differential of nearly 30,000 volts. Any ESD events from this built up charge can result in damage to the fittings 120, 122, valve 124, filters 126, sensor 128 and other components in the fluid circuit 112. Such damage can lead to leaks or spills of fluid, reduced performance in filters 126, sensors 128 or other equipment, and/or ignition of flammable materials or chemicals in the plumbing or in the exterior environment.
Furthermore, the conductive straps 136 and electrical connections for bridging the operative components 118 and for grounding the fluid circuit 112 are required to be manually added. And, depending on the number of fittings, valves, filters, sensors, and other non-conductive operative components in the system, require extensive time and labor to set up. For example, a fluid handling system configured for a wet etch and cleaning process can require nearly two hundred conductive straps to configure the system for ESD mitigation. Additionally, these connections need to be consistently checked and maintained. If one or more of the conductive straps 136 or electrical connections fail, the result is static charge buildup and ESD events which could damage the system 100.
Accordingly, one or more embodiments of the present disclosure are directed to a conductive filter assembly for use in a fluid handling system. In various embodiments, the filter assembly includes a porous fluoropolymer filter membrane and a supporting net positioned directly adjacent to the filter membrane. In one or more embodiments, the supporting net includes a weave of interlaced non-conductive fluoropolymer threads and conductive fluoropolymer threads. In certain embodiments, the filter assembly is pleated, including a pleated filter portion and a pleated supporting net. In some embodiments, the conductive fluoropolymer threads of the supporting net are positioned such that they extend substantially parallel to the pleats of the filter membrane and the supporting net.
In various embodiments, a filter cartridge includes a support tube and a pleated filter. In one or more embodiments the support tube includes a cylindrical sidewall having a plurality of apertures for passage of fluid therethrough and a pair of end caps positioned on ends of the cylindrical sidewall. In various embodiments, one of the pair of end caps includes an inflow aperture for passage of fluid into an interior region of the support tube. In certain embodiments, the filter cartridge includes the pleated filter wrapped directly about an exterior of the cylindrical sidewall and positioned between the pair of end caps. In one or more embodiments, the pleated filter has pleats extending substantially parallel to a longitudinal axis of the cylindrical sidewall.
In various embodiments, one of the pair of end caps includes a conductor portion that is conductively connected to at least one of the conductive fluoropolymer threads to form a conductive pathway from the at least one conductive fluoropolymer thread to the exterior of the end cap.
Certain embodiments of the disclosure are directed to an operative component for a fluid circuit. In one or more embodiments, the operative component includes a body portion and at least two connector portions. In various embodiments the body portion includes a non-conductive fluoropolymer portion that defines a fluid flow path extending between the at least two connector portions. In certain embodiments, the body portion includes a conductive attachment feature for connection of a grounding strap to the body portion for ESD mitigation.
In certain embodiments, the operative component includes the filter cartridge positioned in the fluid flow path. And in one or more embodiments, one of the pair of end caps of the filter cartridge includes a conductor portion conductively connected to at least one of the conductive fluoropolymer threads and to the conductive attachment feature. Accordingly, in certain embodiments, the conductor portion forms a conductive pathway from the at least one conductive fluoropolymer thread to the conductive attachment feature for grounding the pleated filter.
The above summary is not intended to describe each illustrated embodiment or every implementation of the present disclosure.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The drawings included in the present application are incorporated into, and form part of, the specification. They 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.

FIG. 1 depicts a fluid handling system of the prior art.

FIG. 2 depicts an exploded view of a filter assembly, according to one or more embodiments of the disclosure.

FIG. 3 depicts an enlarged view of a supporting net, according to one or more embodiments of the disclosure.

FIG. 4 depicts a cross-sectional view of a weft thread of the supporting net, according to one or more embodiments of the disclosure.

FIG. 5 depicts a cross-sectional view of a filter cartridge, according to one or more embodiments of the disclosure

FIG. 6 depicts an operative component including a filter device, according to one or more embodiments of the disclosure.

FIG. 7 depicts a fluid handling system and fluid circuit, according to one or more embodiments of the disclosure.

FIG. 8 depicts a device for manufacturing a pleated filter assembly, according to one or more embodiments of the disclosure.

While the embodiments of the disclosure are amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the disclosure to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.

DETAILED DESCRIPTION

FIG. 2 depicts a pleated filter assembly 200 according to one or more embodiments of the disclosure. In various embodiments, the pleated filter assembly 200 includes a three-layered filter portion 204. In one or more embodiments the filter portion 204 includes a filter layer 208 which is covered on its inflow side by a pre-filter layer 212 and on its outflow side by a protective layer 216. The inflow side and outflow side of the filter portion 204 is indicated by arrow 220 which depicts the direction of fluid flow through the filter assembly 200.
In various embodiments, each of the layers in the filter portion 204 are a porous fluoropolymer filter membrane. In one or more embodiments, the layers of the filter portion 204 can be constructed from fluoropolymers including, but not limited to, perfluoroalkoxy alkane (PFA), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), and polytetrafluoroethylene (PTFE). For example, in one or more embodiments, at least some of the layers of the filter portion 204 are constructed from a porous PTFE membrane. In certain embodiments, at least some of the layers of the filter portion can be constructed from a porous PFA membrane. In some embodiments, one or more of the layers of the filter portion 204 are constructed from different materials than other layers. For example, the pre-filter layer 212, and protective layer 216 could be constructed from PFA while the filter layer 208 could be constructed from PTFE. In still other embodiments, one or more of the layers in the filter portion 204 can be constructed from other suitable materials including plastic and fiberglass. Additionally, in some embodiments described in greater detail herein, the porous fluoropolymer layers used to form the filter portion 204 are constructed from a coated fluoropolymer membrane that includes a conductive coating. In certain embodiments, the porous polymeric membrane is designed to have a morphology for various filtration applications to remove particles or microorganisms from organic solvents.
Further, while FIG. 2 depicts a filter portion 204 including three layers, in certain embodiments, the filter portion 204 includes additional or fewer layers. For example, in certain embodiments the filter portion 204 includes a single porous fluoropolymer membrane layer.
In one or more embodiments, the filter portion 204 is supported on one or more sides by a supporting net 224 positioned directly adjacent to the filter portion 204. For example, in FIG. 2, filter portion 204 is supported on both the outflow side and the inflow side of the filter portion 204 by the supporting nets 224 which lie surface-to-surface against the pre-filter layer 212 and the protective layer 216. In various embodiments, the filter assembly 200, including both the supporting net 224 and the filter portion 204 are pleated having a plurality of pleats 228 that run substantially parallel to the width of the filter assembly 200.
In operation, in one or more embodiments, the supporting net 224 mechanically supports and protects the membranes of the filter portion 204 from damage due to fluid flow through the filter assembly 200. Additionally, in various embodiments, the supporting net 224 includes channels or openings therein for fluid to pass through the supporting net 224 to the surface of the filter portion 204 and ensures separation between pleats 228 of the filter portion. This is beneficial because if the pleats 228 of the filter membranes are packed directly against each other, they could form a fluid tight seal against one another that blocks flow through the filter assembly 200.
Continuing to refer to FIG. 2, and additionally to an enlarged view of section “A” shown in FIG. 3, in various embodiments, supporting net 224 is constructed to have a woven design formed by interlaced warp threads 232 and weft threads 236. In some embodiments, the supporting net 224 has a mesh or grid design, where interlaced warp threads 232 and weft threads 236 are equally spaced from one another.
In various embodiments, the warp threads 232 are made of non-conductive fluoropolymer threads. In certain embodiments, at least one of the weft threads 236 are conductive weft threads 238 made of a conductive fluoropolymer and a remainder of the weft threads 236 are non-conductive weft threads 240 made from non-conductive fluoropolymer. For example, in some embodiments, at least half of weft threads 236 in the supporting net 224 are conductive weft threads 238. In certain embodiments, all of the weft threads 236 in the supporting net 224 are conductive weft threads 238. And, in some embodiments, only one of the weft threads 236 are conductive weft threads 238.
In one or more embodiments, the warp threads 232 and the non-conductive weft threads 240 are constructed from a non-conductive PFA mono-filament. In some embodiments, the conductive weft threads 238 are constructed from PFA mono-filament loaded with conductive material. For example, in some embodiments weft threads 236 are constructed from loaded PFA. In one or more embodiments, loaded PFA includes, but is not limited to, PFA loaded with carbon fiber, nickel coated graphite, carbon fiber, carbon powder, carbon nanotubes, and metal particles. In certain embodiments, the weft threads 236 and warp threads 232 have a diameter of from approximately 0.02 mm to approximately 0.5 mm, and more particularly from 0.02 mm to 0.1 mm. In certain embodiments, the weft threads 236 and warp threads 232 have a spacing between threads or mesh width from approximately 0.2 mm to approximately 1 mm.
Continuing to refer to FIG. 2 and additionally referring to FIG. 4, in one or more embodiments, the conductive weft threads 238 are constructed from a coextruded filament 441 that includes an inner portion 242 of a conductive fluoropolymer surrounded by an exterior portion 244 of a conductive fluoropolymer. For example, in certain embodiments, the inner portion 242 is constructed of loaded PFA and the exterior portion 244 is constructed of PFA.
In various embodiments, due to the exterior portion 244, the loaded PFA inner portion 242 is entirely non-wetted during fluid filtration by the filter assembly 200. This can prove beneficial in applications such as in filtration of ultra-pure fluid, where the non-conductive PFA exterior portion 244 shields the potentially contaminating loaded PFA from direct contact with fluid to maintain purity standards.
In one or more embodiments, one or more of the layers of the filter portion 204, and/or the supporting net 224 can include electrically conductive coatings. As used herein, a coating refers to a coating that is applied directly to a surface or indirectly to a surface that has already been modified by a surface treatment. For example, a coating on a surface can refer to coating on another pre-existing coating that was already applied to a surface or to a coating on a surface that has undergone a process that alters a chemical composition of that surface.
For example, in some embodiments, a conductive coating can be applied to a PTFE filter membrane used to form one or more layers of the filter portion 204 or other PTFE surfaces. In some embodiments, the coatings may cover the entire surface or a portion thereof. For example, a membrane may be fully coated, coated on one or more sides, or partially coated.
In certain embodiments, the conductive coating used to modify the PTFE filter membrane can include an electrically conductive carbon including any one of carbon fiber, nickel coated graphite, carbon powder, carbon nanotubes, fullerenes (e.g. C60 fullerene), and combinations thereof. In some embodiments, a PTFE filter membrane is modified such that it becomes electrically conductive by contacting the surfaces of the membrane with a suspension containing an electrically conductive carbon material for a sufficient amount of time for the suspension to coat the membrane and then drying the coated membrane using heat to drive off the solvent used to form the suspension. In one or more embodiments, a PTFE filter membrane is modified such that it becomes electrically conductive by coating the PTFE membrane with a conductive polymer of which polyaniline is one example.
In various embodiments, the conductive coatings, conductive weft threads 238, and inner portion 242 of the co-extruded filament 241 have a resistivity level less than about 1×10¹²Ohms Per Square while non-conductive materials have a resistivity level greater than about 1×10¹²Ohms Per Square. In certain embodiments, conductive coatings, conductive weft threads 238, and inner portion 242 of the co-extruded filament 241 have a resistivity level less than about 1×10⁹Ohms Per Square while non-conductive materials have a resistivity level greater than about 1×10⁹Ohms Per Square.
In one or more embodiments, the supporting net 224 is oriented such the weft threads 236 and conductive weft threads 238 run parallel to the pleats 228, while the non-conductive warp threads 232 are aligned perpendicularly to the pleats 228. Accordingly, and described further with reference to FIGS. 5-7, the parallel orientation of the weft threads to the pleats 228 allows discharge of static charges within the adjacent filter portion 204.
FIG. 5 depicts a filter cartridge 300 according to one or more embodiments of the disclosure. In various embodiments, the filter cartridge 300 includes a support tube 304, a pair of upper and lower end caps 308, 312, a pleated filter assembly 316 and an exterior sidewall 320.
In certain embodiments, the support tube 304 includes a sidewall 324 with a generally cylindrical shape having a longitudinal axis 328 and a plurality of apertures 332 for passage of fluid into/out of an interior region 336 defined by the sidewall 324. In one or more embodiments, upper end cap 308 and lower end cap 312 are positioned on respective ends of the cylindrical sidewall 324. In various embodiments, the lower end cap 312 forms a fluid-tight closure to the sidewall 324, while the upper end cap 308 includes an aperture 340 for passage of fluid into/out of the interior region 336 and the filter cartridge 300.
In one or more embodiments, the support tube 304 is surrounded by the pleated filter assembly 316 positioned between the upper end cap 308 and the lower end cap 312. For clarification purposes, the pleated filter assembly 316 is shown in FIG. 5 as a plurality of layers 344, 346, 348, 350, 352. In various embodiments, the pleated filter assembly 316 is substantially similar to the pleated filter assembly 200 shown and described with reference to FIG. 2. For example, in certain embodiments, layers 344, 346, 348, 350, and 352 correspond to supporting net 224, pre-filter layer 212, filter layer 208, protective layer 216, and supporting net 224, respectively.
In one or more embodiments, the pleated filter assembly 316 includes pleats extending parallel to the longitudinal axis 328 of the support tube 304. Accordingly, in certain embodiments, when viewed from a plane perpendicular to the longitudinal axis 328, the pleated filter assembly 316 is in the shape of a star with radially outwardly extending pleat crests and radially inwardly extending pleat roots following one another alternately along the circumference of the support tube 308. Furthermore, and as discussed in FIG. 2, in one or more embodiments, the supporting nets 344, 352 include warp threads constructed from a non-conductive fluoropolymer and weft threads including at least one conductive weft thread constructed from a conductive fluoropolymer. In various embodiments, the supporting nets 344, 352 are oriented such that they include weft threads that are aligned perpendicularly to the pleats and to the longitudinal axis 328.
In certain embodiments, the exterior sidewall 320 has a generally cylindrical shape and is positioned between the end caps 308, 312, surrounding the filter assembly 316 and the support tube 304. The exterior sidewall 320 includes a plurality of apertures 356 for passage of fluid through the exterior sidewall 320.
In one or more embodiments, the support tube 304, end caps 308, 312, and exterior sidewall 320 are constructed from a fluoropolymer, or other suitable polymeric material. For example, in certain embodiments, the support tube 304, end caps 308, 312, and exterior sidewall 320 are constructed using PTFE, PFA, ETFE, and/or FEP. In certain embodiments, the support tube 304, end caps 308, 312, and exterior sidewall 320 can include conductive portions in addition to, or instead of a typical fluoropolymer material.
For example, depicted in FIG. 5, the upper end cap 308 includes a conductor portion 360 in an exterior layer that surrounds the upper end cap 308. In one or more embodiments, the conductor portion 360 is constructed from a conductive material such as loaded PFA, or other conductive polymer and is formed via overmolding the exterior layer onto an interior portion 364 of the end cap 308. In certain embodiments, the end cap 308 can include a larger or smaller conductor portion 360. For example in some embodiments, the end cap 308 could be entirely constructed from a conductive polymeric material.
In an additional example, in certain embodiments, one or more of the support tube 304 and the exterior sidewall 320 could include a conductor portion constructed from a conductive material such as loaded PFA, or other conductive polymer and formed via overmolding an exterior conductive layer into an interior non-conductive portion. The conductor portion could be oriented longitudinal along the support tube 304 and/or exterior sidewall 320 to transfer static charge along the length of the filter assembly 316. Additionally, in one or more embodiments, the support tube 304 and/or exterior sidewall 320 could be outfitted with a conductive strap to connect to an electrical contact or wire for grounding the filter cartridge 300.
When assembled, the conductor portion 360 of the upper end cap 308 directly contacts the supporting nets 344, 352 and one or more of the longitudinally aligned conductive fluoropolymer weft threads. Accordingly, the upper end cap 308 forms an electrical pathway along the longitudinal length of the filter assembly 316 and across the upper end cap 308 to an exterior portion 368 for grounding the pleated filter assembly 316.
For example, in operation, fluid to be filtered via the filter cartridge 300 may be supplied from the outside of the filter cartridge 300, so that it can flow radially through the exterior sidewall 320, through the pleated filter assembly 316 through the support tube 304 and into the interior region 336 of the support tube 304. The filtered fluid may then subsequently flow in the longitudinal direction of the support tube 304 through the aperture 340 and out of the filter cartridge 300. Due to frictional forces between the filter assembly 316 and fluid as it passes into the interior region 336, static charges maybe generated within the filter assembly 316.
However, due to the one or more conductive fluoropolymer weft threads of the supporting net 344, 352, and the conductor portion 360 of the end cap 308, static charge can flow from the filter assembly 316, upwardly toward the upper end cap 308 for static dissipation. Described further, with reference to FIGS. 6 and 7, the static charge can then be dispersed to ground via the upper end cap 308.
FIG. 6 depicts an operative component 400 configured as a filter device, according to one or more embodiments of the disclosure. In various embodiments, the operative component 400 includes a body portion 404, at least two connector portions 408, and a filter cartridge 412 mounted in the interior of the body portion 404 and directly in a flow path between each of the connector portions 408. In certain embodiments, the flow path is defined by a non-conductive fluoropolymer portion 416 of the body portion 404 that extends between the connector portions 408.
In one or more embodiments, one of the connector portions 408 serves as an intake portion 420, receiving fluid into the interior of the body portion 404 and directing it in direction indicated by arrow 424, towards the other connector portion 408 which serves as an outtake portion 428. In order to pass through the outtake portion 428, fluid is forced through the filter cartridge 412 for filtration of the fluid.
In certain embodiments, body portion 404 includes an outer conductor portion 432 that extends across the body portion 404 between each of the connector fittings 408 and is exposed at the outer surface of the body portion 404. Exposed outer surfaces of the body portion 404 that are included as a part of the outer conductor portion 432 are indicated by reference numeral 434.
In some embodiments, the outer conductor portion 432 is an outer layer of conductive polymer material, such as carbon loaded PFA, or other suitable conductive polymer, that is inlaid, via an overmolding process, into the non-conductive fluoropolymer portion 416 of the body portion 404 to form a continuous path of conductor material that is unitary with the body portion 404 and that extends between each of the connector fittings 408.
In certain embodiments, the outer conductor portion 432 is formed as a strip of material running across the body portion 404 that forms approximately 5-10% of the exterior surface of the body portion 404. In some embodiments, the outer conductor portion 432 is larger, forming approximately 40%-90% of the exterior surface or, in some embodiments, entire exterior surface of the body portion 404. In certain embodiments, the outer conductor portion 404 may be formed of a thin conductive film at the surface of the body portion 404 or incorporated on the thin film. In various embodiment, the thin film is wrapped around a portion of the body portion 404 and extends between each of the connector fittings 408.
In some embodiments, the body portion 404 includes a conductive attachment feature 436 for connection of a grounding strap. In various embodiments, the attachment feature 436 is constructed as a connector boss. The connector boss is a piece of conductive material that is conductively connected with the outer conductor portion 432 for attachment to an electrical contact. For example, connector boss can be connected to an electrical contact to ground the operative component 400 for ESD mitigation. In one or more embodiments, the attachment feature 436 is threaded for attachment to a nut or other threaded connector. However, in certain embodiments, the attachment feature 436 can be configured for interference fit, snap fit, friction fit, or other method of fitting with an electrical contact.
In one or more embodiments the filter cartridge 412 is the same or substantially similar to the filter cartridge 300 of FIG. 5. For example, the filter cartridge 412 includes a pleated filter assembly 440 wrapped directly about a cylindrical sidewall and positioned between a pair of end caps 444, 448. A supporting net 452 is positioned directly adjacent to the filter assembly 440 and includes a mesh of non-conductive fluoropolymer warp threads 456 and conductive fluoropolymer weft threads 460. Depicted in FIG. 6, the mesh of warp threads 456 and weft threads 460 are enlarged for clarification. In various embodiments, the filter cartridge 412 is mounted in the interior of the body portion via the upper end cap 444.
In one or more embodiments, the body portion 404 includes an interior conductor portion 464 that extends inwardly to from the outer conductor portion 432 to form an electrical contact with a conductive portion in the filter cartridge 412.
In assembly, in one or more embodiments, when the filter cartridge 412 is mounted in the body portion 404, upper end cap 444 and interior conductor portion 464 contact to form a conductive pathway along the longitudinal length of the filter assembly 440, via the fluoropolymer weft threads 460, to the outer conductor portion 432 and the conductive attachment feature 436.
Accordingly, in operation, as fluid is filtered through the operative component 400, static charges in the filter assembly 440 can be dissipated via a grounded electrical contact attached to attachment feature 436 and/or conductive tubing connected to one or more of the connector portions 408.
FIG. 7 depicts a fluid handling system 500 according to one or more embodiments of the disclosure. The system 500 provides a flow path for fluid to flow from a fluid supply 504 to one or more process stages 508 positioned downstream. System 500 includes a fluid circuit 512 which includes a portion of the flow path of the fluid handling system 500. The fluid circuit 512 includes tubing segments 516 and a plurality of operative components 520 that are interconnected via the tubing segments 516. Depicted in FIG. 7, the operative components 520 include an elbow shaped fitting 522, T-shaped fitting 524, a valve 526, and filter devices 528. However, in various embodiments the fluid circuit 512 can include additional or fewer operative components 520 in number and in type. For example, the fluid circuit 512 could substitute or additionally include pumps, mixers, dispense heads, sprayer nozzles, or other types of operational components.
In certain embodiments, the operational components 520 each include a body portion 532 that defines fluid flow passageway therethrough and one or more tubing connector fittings 536. In some embodiments, at least one of the tubing connector fittings 536 is an inlet portion for receiving fluid into the body portion 532 and at least another one of the tubing connector fittings 536 is an outlet portion for outputting fluid received via the inlet portion.
For example, filter devices 528 each include one tubing connector fitting 536 that is an inlet portion that receives fluid from the fluid supply 504 and a tubing connector fitting 536 which is an outlet portion outputting fluid toward the process stages 508. In certain embodiments, the inlet portion and the outlet portion are each connected or connectable to a tubing segment 516.
Tubing segments 516 are partially conductive, having a main portion or tubing portion constructed from non-conductive or low conductive material and having a secondary portion constructed from a conductive material that extends axially along the length of the tubing portion. For example, in some embodiments, tubing segments 516 each include a tubing portion of a non-conductive fluoropolymer and secondary portion formed as a strip of conductive polymer extending axially on and unitary with the non-conductive fluoropolymer tubing portion. In certain embodiments, tubing portion is constructed from PFA with the one or more conductive strips of the secondary portion constructed from carbon loaded PFA that is extruded along the length of each of the tubing segments 516 at or near its exterior surface. In some embodiments, the tubing segments 516 in the fluid circuit 512 are FLUOROLINE®, PFA tubing.
Described above, with reference to FIGS. 2-6, in one or more embodiments, the filter devices 528 each include a conductive filter cartridge enclosed within the body portion 532. In various embodiments, the body portion 532 includes a conductive attachment feature for connecting the filter cartridge within the body portion 532 to ground 540 (FIG. 7). Additionally, in certain embodiments, one or more of the tubing connector fittings 536 are constructed using a conductive material to form a conductor portion that provides an electrical path across the body portion 532 of the filter device 528 via each of the tubing connector fittings 536.
In various embodiments, the conductor portion is a strip or segment of conductive material inlaid unitary with the tubing connector fittings 536 and body portion 532 and is constructed from a conductive polymeric material. For example, in some embodiments the outer conductor portion is constructed from PFA loaded with conductive material (e.g. loaded PFA).
In various embodiments, each of the filter devices 528 includes a bridging component, in the form of the outer conductor portion, for conductively connecting the respective outer conductive portion of the body portion 532 to the strips of conductive polymer of the tubing segments 516 that are connected to the operative components 520. As such, in certain embodiments, the filter devices 528 and tubing segments 516 form an electrical pathway that eliminates some of the breaks in conductivity in the fluid circuit and reduces the difficulty of configuring the fluid circuit 512 for ESD mitigation. A circuit diagram 544 is superimposed over the fluid circuit 512 to illustrate the electrical pathway.
FIG. 8 depicts a system 600 for manufacturing a pleated filter assembly 604 according to one or more embodiments of the disclosure. In various embodiments, the system 600 includes a filter portion supply 608 and supporting net supplies 612 configured as drums of polymeric filter material and supporting net material as described above with reference to FIGS. 2-4. In one or more embodiments, the materials are pulled off their respective drums and sealed, fused, sewn, or otherwise secured together to form an unpleated filter assembly 616. In various embodiments, once the unpleated filter assembly 616 is formed, it is pleated via pleating device 620 using heat treating, sewing, or other suitable process to output the final pleated filter assembly 604.
The following clauses define particular aspects and embodiments of the invention.
Clause 1. A pleated filter comprising: a porous fluoropolymer filter membrane; a supporting net positioned directly adjacent to the filter membrane on at least one of an outflow side of the filter membrane and an inflow side of the filter membrane, the supporting net including a weave of non-conductive fluoropolymer threads and one or more conductive fluoropolymer threads, the conductive fluoropolymer threads extending substantially parallel to pleats of the filter membrane and the supporting net.
Clause 2. The pleated filter of clause 1, wherein the supporting net includes warp threads from the non-conductive fluoropolymer threads, and weft threads including one or more conductive weft threads from the one or more conductive fluoropolymer threads that extend substantially parallel to pleats of the filter membrane.
Clause 3. The pleated filter as in any one of clauses 1 and 2, wherein the weft threads include one or more non-conductive weft threads from the non-conductive fluoropolymer threads.
Clause 4. The pleated filter as in any one of clauses 1-3, wherein the non-conductive fluoropolymer threads are perfluoroalkoxy alkane (PFA) mono-filament and the one or more conductive fluoropolymer threads are perfluoroalkoxy alkane (PFA) mono-filament loaded with a conductive material.
Clause 5. The pleated filter as in any one of clauses 1-4, wherein the one or more conductive fluoropolymer threads are a coextruded filament including an inner portion of perfluoroalkoxy alkane (PFA) fluoropolymer loaded with a conductive material and an exterior portion of perfluoroalkoxy alkane (PFA).
Clause 6. A filter cartridge comprising: a support tube including a cylindrical sidewall including a plurality of apertures for passage of fluid therethrough, the support tube including a pair of end caps positioned on ends of the cylindrical sidewall, one of the pair of end caps including an aperture for passage of fluid from an interior region of the support tube; and
a pleated filter wrapped directly about an exterior of the cylindrical sidewall and positioned between the pair of end caps, the pleated filter having pleats extending substantially parallel to a longitudinal axis of the cylindrical sidewall, the pleated filter including: a porous fluoropolymer filter membrane; and a supporting net positioned directly adjacent to the filter membrane on at least one of an outflow side of the filter membrane and an inflow side of the filter membrane, the supporting net including a weave of non-conductive fluoropolymer threads and one or more conductive fluoropolymer threads, the one or more conductive fluoropolymer threads extending substantially parallel to pleats of the filter membrane and the supporting net;
wherein, one of the pair of end caps includes a conductor portion conductively connected to at least one of the conductive fluoropolymer threads and forming a conductive pathway from the at least one conductive fluoropolymer thread to the exterior of the end cap.
Clause 7. The filter cartridge of clause 6, wherein the supporting net of the pleated filter includes warp threads from the non-conductive fluoropolymer threads, and weft threads including one or more conductive weft threads from the one or more conductive fluoropolymer threads.
Clause 8. The filter cartridge as in any one of clauses 6-7, wherein the weft threads include one or more non-conductive weft threads from the non-conductive fluoropolymer threads.
Clause 9. The filter cartridge as in any one of clauses 6-8, wherein the non-conductive fluoropolymer threads are perfluoroalkoxy alkane (PFA) mono-filament and the one or more conductive fluoropolymer threads are loaded perfluoroalkoxy alkane (PFA) mono-filament.
Clause 10. The filter cartridge as in any one of clauses 6-9, wherein the conductive fluoropolymer threads are a coextruded filament including an inner portion of loaded perfluoroalkoxy alkane (PFA) and an exterior portion of perfluoroalkoxy alkane (PFA).
Clause 11. A pleated filter comprising: a porous fluoropolymer filter membrane; and a supporting net positioned directly adjacent to the filter membrane on at least one of an outflow side of the filter membrane and an inflow side of the filter membrane; wherein at least one of the porous fluoropolymer filter membrane and the supporting net has a surface including an electrically conductive coating.
Clause 12. The pleated filter of clause 11, wherein both the porous fluoropolymer filter membrane and the supporting net include an electrically conductive coating.
Clause 13. The pleated filter as in any one of clauses 11-12, wherein the membrane is a porous polymeric membrane with a morphology to remove particles or microorganisms from organic solvents.
Clause 14. The pleated filter as in any one of clauses 11-13, wherein the coating comprises carbon nanotubes.
Clause 15. The pleated filter as in any one of clauses 11-14, wherein the coating comprises a Fullerene.
Clause 16. The pleated filter as in any one of clauses 11-15, wherein the electrically conductive coating is effective to dissipate a build-up of an electrostatic charge that is on the surface.
Clause 17. An operative component for a fluid circuit comprising:
a body portion and at least two connector portions, the body portion comprising a non-conductive fluoropolymer portion that defines a fluid flow path extending between the at least two connector portions, the body portion including an exterior conductive attachment feature for connection of a grounding strap to the body portion; and a pleated filter positioned in the fluid flow path, the filter including: a porous fluoropolymer filter membrane; and a supporting net positioned directly adjacent to the filter membrane on at least one of an outflow side of the filter membrane and an inflow side of the filter membrane, the supporting net including a weave of non-conductive fluoropolymer threads and one or more conductive fluoropolymer threads, the one or more conductive fluoropolymer threads extending substantially parallel to pleats of the filter membrane and the supporting net; wherein, the exterior conductive attachment feature is conductively connected to at least one of the one or more conductive fluoropolymer threads thereby forming a conductive pathway from the pleated filter to an exterior of the operative component for grounding the pleated filter.
Clause 18. The operative component of clause 17, wherein the body portion further comprises a non-interior fluoropolymer conductor unitary with the non-conductive fluoropolymer portion, the non-interior fluoropolymer conductor extending between the at least two connector portions, each connector portion configured for receiving a tubing end having a conductive portion and conductively connecting the non-interior fluoropolymer conductor portion to the conductive portion of the tubing end.
Clause 19. A fluid circuit defining a flow path for a fluid from a fluid supply toward a process stage, the fluid circuit comprising:
a plurality of operative components, each operative component comprising a fluoropolymer body portion with a fluid flow passageway therethrough and a plurality of tubing connector fittings, the operative components connected by a plurality of tubing segments connecting to the components at their respective tubing connector fittings, the plurality of tubing segments and operative components providing the flow path through the fluid circuit;
wherein a path to ground is provided that extends through or from each operative component and each tubing segment.
Clause 20. The fluid circuit of clause 19, wherein one of the plurality of operative components is a conductive filter, and wherein the conductive filter includes a fluoropolymer filter membrane having a surface with a layer comprising an electrically conductive coating.
Clause 21. The conductive fluoropolymer threads as in any one of clauses 1-10 or 17-18, wherein there resistivity of the threads is less than about 1×10¹²Ohms Per Square.
Clause 22. The conductive fluoropolymer threads as in any one of clauses 1-10 or 17-18, wherein there resistivity of the threads is less than about 1×10⁹Ohms Per Square.
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.

Claims

What is claimed is:

1. A pleated filter comprising:

a porous fluoropolymer filter membrane;

a supporting net positioned directly adjacent to the filter membrane on at least one of an outflow side of the filter membrane and an inflow side of the filter membrane, the supporting net including a weave of non-conductive fluoropolymer threads and one or more conductive fluoropolymer threads, the conductive fluoropolymer threads extending substantially parallel to pleats of the filter membrane and the supporting net.

2. The pleated filter of claim 1, wherein the supporting net includes warp threads from the non-conductive fluoropolymer threads, and weft threads including one or more conductive weft threads from the one or more conductive fluoropolymer threads.

3. The pleated filter of claim 2, wherein the weft threads include one or more non-conductive weft threads from the non-conductive fluoropolymer threads.

4. The pleated filter of claim 1, wherein the non-conductive fluoropolymer threads are perfluoroalkoxy alkane (PFA) mono-filament and the one or more conductive fluoropolymer threads are loaded perfluoroalkoxy alkane (PFA) mono-filament.

5. The pleated filter of claim 1, wherein the one or more conductive fluoropolymer threads are a coextruded filament including an inner portion of loaded perfluoroalkoxy alkane (PFA) and an exterior portion of perfluoroalkoxy alkane (PFA).

6. A filter cartridge comprising:

a support tube including a cylindrical sidewall including a plurality of apertures for passage of fluid therethrough, the support tube including a pair of end caps positioned on ends of the cylindrical sidewall, one of the pair of end caps including an aperture for passage of fluid from an interior region of the support tube; and

a pleated filter wrapped directly about an exterior of the cylindrical sidewall and positioned between the pair of end caps, the pleated filter having pleats extending substantially parallel to a longitudinal axis of the cylindrical sidewall, the pleated filter including:

a porous fluoropolymer filter membrane; and

a supporting net positioned directly adjacent to the filter membrane on at least one of an outflow side of the filter membrane and an inflow side of the filter membrane, the supporting net including a weave of non-conductive fluoropolymer threads and one or more conductive fluoropolymer threads, the one or more conductive fluoropolymer threads extending substantially parallel to pleats of the filter membrane and the supporting net;

wherein, one of the pair of end caps includes a conductor portion conductively connected to at least one of the conductive fluoropolymer threads and forming a conductive pathway from the at least one conductive fluoropolymer thread to the exterior of the end cap.

7. The filter cartridge of claim 6, wherein the supporting net of the pleated filter includes warp threads from the non-conductive fluoropolymer threads, and weft threads including one or more conductive weft threads from the one or more conductive fluoropolymer threads.

8. The filter cartridge of claim 7, wherein the weft threads include one or more non-conductive weft threads from the non-conductive fluoropolymer threads.

9. The filter cartridge of claim 6, wherein the non-conductive fluoropolymer threads are perfluoroalkoxy alkane (PFA) mono-filament and the one or more conductive fluoropolymer threads are loaded perfluoroalkoxy alkane (PFA) mono-filament.

10. The filter cartridge of claim 6, wherein the conductive fluoropolymer threads are a coextruded filament including an inner portion of loaded perfluoroalkoxy alkane (PFA) and an exterior portion of perfluoroalkoxy alkane (PFA).

11-16. (canceled)

17. An operative component for a fluid circuit comprising:

a body portion and at least two connector portions, the body portion comprising a non-conductive fluoropolymer portion that defines a fluid flow path extending between the at least two connector portions, the body portion including an exterior conductive attachment feature for connection of a grounding strap to the body portion; and

a pleated filter positioned in the fluid flow path, the filter including:

a porous fluoropolymer filter membrane; and

wherein, the exterior conductive attachment feature is conductively connected to at least one of the one or more conductive fluoropolymer threads thereby forming a conductive pathway from the pleated filter to an exterior of the operative component for grounding the pleated filter.

18. The operative component of claim 17, wherein the body portion further comprises a non-interior fluoropolymer conductor unitary with the non-conductive fluoropolymer portion, the non-interior fluoropolymer conductor extending between the at least two connector portions, each connector portion configured for receiving a tubing end having a conductive portion and conductively connecting the non-interior fluoropolymer conductor portion to the conductive portion of the tubing end.

19-20. (canceled)