Process and apparatus for bonding a pair of ducts together...

Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor

Reexamination Certificate

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Details

C156S304200, C156S304600, C156S499000, C156S503000

Reexamination Certificate

active

06409873

ABSTRACT:

FIELD OF THE INVENTION
The present invention is in the field of forming joints between pipes, ducts, and fittings. The present invention is particularly useful in joining ducts together in order to preassemble encapsulating structures for processing equipment used in the manufacture of microelectronic devices, particularly with inert polymer materials, because the resultant joints between the encapsulation member components are accurately aligned, substantially distortion free, strong for long service life, and impermeable to metal ions.
BACKGROUND OF THE INVENTION
There are many circumstances in which it is desirable to encapsulate a substrate with some kind of protective barrier. In some circumstances, encapsulation can be used to protect the substrate from the environment in which the substrate will be used. For example, encapsulation is useful when the substrate is a metal component or the like that is to be used in a marine environment where salt water or the corresponding vapor or mist can corrode or otherwise damage the unprotected component. Encapsulation can also be used to protect processing equipment to be used in acidic, basic, reducing, or oxidizing environments.
In other circumstances, it may be desirable to protect items in the environment from the substrate itself. For instance, one step of manufacturing microelectronic devices involves processing those devices while the devices are supported upon some kind of structure, such as a wafer cassette, platform, transport apparatus, rotating turntable, and/or the like. For strength, rotating turntables and other structures used to process microelectronic devices are often formed from one or more metals, metal alloys, intermetallic compositions, or the like. Unfortunately, metal ions from such metallic structures can migrate from the structures into the devices being processed. This is especially problematic and may even destroy the functional capability of the devices. To protect microelectronic devices from contamination during processing, the industry has encapsulated one or more components of the processing equipment in an inert polymer, e.g., a fluoropolymer such as perfluoroalkoxy polymer (PFA), a fluoroethylene polymer (FEP), an ethylene tetra fluoroethylene polymer, (ETFE), a polyvinylidene fluoride polymer (PVDF), a polyvinyl fluoride polymer (PVF), combinations of these, and the like.
To encapsulate a particular structure with an inert polymer, one or more encapsulating parts may be pre-formed and then assembled around the structure. The parts may be joined using glue, fusing techniques, or the like. In the microelectronics industry, the encapsulating joints must be strong enough so that the encapsulated structure can withstand the rigors of use over a reasonably long service life. If the substrate comprises metal, the encapsulation joint should be impermeable to metal ions.
Forming encapsulating joints that meet the stringent demands of the microelectronic industry has been extremely challenging. The difficulty is due, at least in part, to the complex geometry of the structures that require encapsulation. For example, the MERCURY® centrifugal spray processors commercially available from FSI International, Chaska, Minn., each include an encapsulated, rotating turntable that supports several wafer cassettes during processing. This turntable has projecting, upright structures including uprights that help hold the wafer cassettes. It previously has been difficult and time consuming to satisfactorily bond encapsulating structures in position over these uprights. Generally, to form such an encapsulating structure, an encapsulating top cover is positioned over the top of the turntable. The top cover has a number of apertures matched to the upright structures so that the uprights project upward through these apertures when the cover is in place. Encapsulating sleeves are placed over these uprights and then bonded to the top cover. In short, the encapsulating structure is assembled around the turntable.
It would be much more desirable to be able to preassemble the top cover and sleeves and then fit the preassembled structure over the uprights and turntable like a glove. However, there are a number of challenges that would have to be overcome in order for this approach to be feasible. First, the sleeves must be accurately positioned when bonded to the cover. To appreciate this, it is helpful to consider that the pre-assembly of the sleeve and cover generally involves joining the mating faces of a pair of ducts together. The sleeve is a duct closed at one end, but open at the other. The cover itself will include a number of through apertures through which the uprights of the turntable project when the cover is positioned over the turntable. The open end of the tube must be bonded to the cover so that the opening of the tube is accurately positioned over a corresponding opening through the cover. Any misalignment between these ducts may prevent the pre-assembled cover from properly fitting over the turntable.
Additionally, methods for bonding encapsulating components together require that the mating faces of the parts be pressed into contact with each other using some pressure while the joint between the parts fuses. Depending upon whether glue or fusion techniques are being used, a bead of glue or molten material, as the case may be, tends to form around the joint on both the inside and outside of the resultant structure. The formation of such a bead on the interior is particularly problematic because the bead reduces the interior cross-section of the structure. The reduced cross-section can make it difficult, or impossible, to fit the encapsulated structure over the turntable, even if alignment between the bonded parts is accurate.
Third, the cross-sectional shape of each sleeve is generally carefully matched to that of the corresponding upright so that the sleeve fits over the upright with little, if any, play. In some instances, the methods used to press the sleeve into bonding contact with the cover during a conventional preassembly can distort the cross-section of the sleeve. This distortion, too, tends to cause a poor fit over the turntable uprights.
Fourth, the bond must be strong enough to withstand the rigors of the intended use. If the bond fails, the integrity of the encapsulating structure is obviously compromised. Desirably, therefore, the joint between components should be at least as strong as the materials being joined.
Preassembling encapsulating structures is not the only situation in which mating faces of ducts must be accurately bonded together. Indeed, this issue arises in any circumstance in which ducts, whether encapsulating components, pipes, fittings, or the like, are joined together. For example, when joining pipes together to form a fluid transport system, misalignment, bead formation on the interior of joined pipes, a weak joint, and/or distorted cross-sections can impede fluid flow through the assembled pipes. In some instances, larger, more expensive pumps might be required to provide fluid transport due to the additional, undue pressure drop caused by such problems. In other instances in which fluids must be transferred through piping under laminar flow conditions, such problems can cause intolerable turbulence to occur.
There is thus a continuing need for improved processes and structures for accurately joining ducts together, particularly when pre-assembling encapsulating structures or when assembling networks for transporting fluids. An effective and efficient process and apparatus that provides a clean, accurate, nondistorted, durable, impermeable bond between duct components would be highly desirable.
SUMMARY OF THE INVENTION
The present invention advantageously provides an approach for accurately joining ducts together such that the joint is clean, accurate, nondistorted, durable, and impermeable to metal ions. The present invention is based, at least in part, upon the concept of using a removable alignment member that can be used to support ducts while the ducts are being joined.

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