Abstract:
An apparatus for collecting condensed vapor during physical vapor deposition includes an enclosure configured to be placed adjacent to one or more vapor sources in a vacuum chamber. The enclosure includes an internal surface of the enclosure partially enclosing a volume of space configured to receive an object wherein the enclosure is maintained at a cooler temperature than the one or more vapor sources. The internal surface of the enclosure is coupled to one or more drainage gutters drainage drainage gutters.

Description:
FIELD 
       [0001]    This disclosure relates generally to vapor collection, and specifically, to the condensation and collection of vapor. 
       BACKGROUND 
       [0002]    Thin film magnetic and magneto-optical (MO) media in disc form are typically lubricated with a thin film of a polymeric lubricant, e.g., a perfluoropolyether, to reduce wear of the disc when utilized with data/information recording and read-out heads/transducers operating at low flying heights, as in a hard disc system functioning in both contact start-stop (“CSS”) and load/unload (“L/UL”) modes. Conventionally, a thin film of lubricant is applied to the disc surface(s) during manufacture by dipping a disc with a stack of thin film layers formed thereon, including at least one recording layer, into a bath containing a small amount of lubricant, e.g., less than about 1% by weight of a fluorine-containing polymer, dissolved in a suitable solvent, typically a perfluorocarbon, fluorohydrocarbon, or hydro fluoroether. However, a drawback inherent in such dipping process is the consumption of large quantities of solvent, resulting in increased manufacturing cost and concern with environmental hazards associated with the presence of toxic or otherwise potentially harmful solvent vapors in the workplace. 
         [0003]    Vapor deposition of thin film lubricants is an attractive alternative to dip lubrication in view of the above drawbacks. Specifically, vapor deposition of lubricant films is a solvent free process. Moreover, vapor deposition techniques can provide up to about 100% bonded lubricant molecules when utilized with appropriate polymeric lubricants and magnetic and/or MO disc substrates having deposition surfaces comprised of a freshly-deposited carbon-based protective overcoat layer which is not exposed to air prior to lubricant deposition thereon. 
       SUMMARY 
       [0004]    In an aspect of the disclosure, an apparatus for collecting condensed vapor during physical vapor deposition includes an enclosure configured to be placed adjacent to one or more vapor sources in a vacuum chamber. The enclosure includes an internal surface of the enclosure partially enclosing a volume of space configured to receive an object wherein the enclosure is maintained at a cooler temperature than the one or more vapor sources. The internal surface of the enclosure is coupled to one or more drainage gutters drainage drainage gutters. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0005]    Embodiments of this disclosure are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which: 
           [0006]      FIG. 1  illustrated an embodiment of a conventional vapor lubrication system configuration. 
           [0007]      FIG. 2A  illustrates a side view of an apparatus to contain and condense lubricant vapor in accordance with an embodiment. 
           [0008]      FIG. 2B  illustrates a front edge view of the apparatus of  FIG. 2A . 
           [0009]      FIG. 2C  illustrates a top edge view of the apparatus of  FIG. 2A . 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    Referring to  FIG. 1A , in a physical vapor deposition process for disc drive media lubricants, a deposition system  120  includes a thermal source  101  heats liquid lubricant in a vapor source  110 , both of which are contained in a vacuum chamber  108  to produce a lubricant vapor. The heated lubricant may have a higher vapor pressure than the lubricant at ambient or below ambient temperatures. The lubricant vapor is effused from the vapor source  110  through an array of holes in a heated diffuser plate  112  to a space in the vacuum chamber  108  where an unheated object may be coated with the lubricant. The vapor travels across a gap under vacuum conditions and condenses on the unheated object surface which, for example, may be a disc. In one embodiment, the disc may be exposed to the effused vapor from one side by a single heated vapor source  110 . In another embodiment, the disc may be exposed from both sides, using two heated vapor sources. The diffuser plate  112  is is provided to produce a spatially uniform film across the surface of the disc. While the array of holes and the gap between the vapor source  110  and the disc are designed to maximize line-of-sight deposition of the vapor, the effusive nature of the vapor through the holes in the diffuser plate  112  results in a significant amount of lubricant that is not deposited on the disc surface. This unused lubricant may conventionally condense on walls of the vacuum chamber  108  or be removed by a pumping system coupled to the vacuum chamber  108 . In either case, the lubricant is not utilized on the disc and is considered lost. In addition to the added costs due to unutilized lubricant, lubricant condensed inside the vacuum chamber  108  or system pumps can have other detrimental effects, such as premature pump failure. 
         [0011]    Referring to  FIG. 1B , a physical vapor deposition process for disc drive media lubricants, a deposition system  120 ′ may include some or all of the elements of the deposition system  120 , but further includes an enclosure  200 . Details of the enclosure  200  are described below. 
         [0012]      FIG. 2A  is a front-view of apparatus  200  to contain and collect lubricant vapor that would otherwise be deposited on interior walls of the vacuum chamber  108  containing the apparatus  200 . In an embodiment, the apparatus  200  is configured to be placed opposite one or more vapor sources  110 , the vapor sources  110  substantially facing opposite sides of an object which, for example, may be a disc, such as a magnetic memory disc or a magneto-optical disc. In an embodiment, two vapor sources  110  face each other, with the disc in between the two vapor sources  110 . The apparatus  200  includes an enclosure  230  that may enclose a space between the two vapor sources  110  containing the disc. The low thermal conductivity of the spacers  240  may prevent or retard the heat of the vapor source  110  from heating the enclosure  230 . To enable more efficient condensation of the vapor, thermally insulating spacers  240  may mechanically couple either side of the enclosure  230  to a corresponding vapor source  110  while providing a measure of thermal isolation of the enclosure  230  from the hot vapor sources  110 , and maintaining a restricted gap to reduce the amount of vapor lubricant that may undesirably enter the enclosure  230 . 
         [0013]    By maintaining a larger temperature differential between the hotter vapor source  110  and the cooler enclosure  230 , the rate of vapor condensation on the enclosure is made greater. Ceramics and some metals are known to have low thermal conductivity. For example, alumina and other ceramics have thermal conductivity in the approximate range of 10-50 W/m-° K. Certain stainless steels, such as 316 and 316L have thermal conductivities on the order of 15-30 W/m-° K, and Inconel™ has a thermal conductivity on the order of about 15-20 W/m-° K. Such materials may be characterized as having low thermal conductivity. For comparison, aluminum metal has a high thermal conductivity on the order of about 200 W/m-° K. 
         [0014]    The enclosure  230  may have a generally polygonal, oval, circular or similar shape that includes an upper shield  231  and a lower shield  232 . Each shield includes an arched-shaped surface  234  where the apex of the arch is approximately in-line and concentric with a planar surface of the disc and forms a substantially outermost boundary of the shields  231 ,  232  with respect to the center of the disc. In the upper shield  231 , condensed vapor may flow downwards and away from the plane of the disc by the action of gravity along an inner surface of the shield  231  so that condensed vapor may not drip onto the disc. In the lower shield  232  the arch acts as a trough in which condensed vapor may flow downwards by the action of gravity, substantially collecting below the disc. At least the upper shield  231  also includes drainage gutters  245  at each “foot” of the arch surface  234  to capture condensed vapor as it flows downward to prevent it from potentially running over the diffuser plate  112  of the vapor source  110 , to avoid condensed vapor dripping on the disc, and further to avoid condensed vapor dripping out of the enclosure  230 . A drain  250  coupled to the lower shield  232  directs the condensed vapor to a reservoir  265  for storage. The stored condensed vapor may be re-used in subsequent vapor deposition. Alternatively, the stored condensed vapor may be continuously recycled to the vapor source  110  for possible immediate re-use. 
         [0015]    Because the vapor pressure may be quite low at ambient temperature (e.g., room temperature) or lower temperature, increasing the temperature differential between the vapor source  110  and the enclosure  230  by lowering the temperature of the enclosure may provide an increased condensation efficiency, and reduce an amount of the vapor that may accumulate in parts of the vacuum chamber  108  or pumping system. Therefore, a one or more cooling plates  290  having high thermal conductivity may be arranged with the enclosure  230  to provide additional sub-ambient cooling transfer of heat away from the enclosure  230  and greater temperature differential between the enclosure  230  and the vapor source  110 . Sub-ambient cooling may be accomplished with several different structures, including coupling the cooling plates  290  to heat dissipation fins (not shown) external to the vacuum chamber  108 , Peltier coolers (not shown), fluid heat transfer apparatus (not shown), or the like. 
         [0016]    A small narrow throat aperture  254  at a bottom of the enclosure  230  shield  232  may provide for insertion and removal of the disc for the deposition process. The aperture  254  may be kept to minimum dimensions to allow for insertion and removal of the disc while reducing an amount of vapor that may escape the enclosure to reach the walls of the vacuum chamber or the pumping system. 
         [0017]    The enclosure  230  may be constructed of a material having a low rate of oxidation. In addition, a low thermal conductivity material, such as stainless steel 316, 16L and Inconel™, or the like, may reduce heating of the enclosure  230 , thereby maintaining a higher rate of condensation of the vapor. A polished internal surface of the enclosure may promote better flow and drainage of the condensed vapor. For the sake of maintaining the chemical stability and purity of the vapor deposited on the disc, or other object, the enclosure material may be selected to have a substantially negligible rate of outgassing, a substantially negligible rate of corrosion, and inertness to chemical reaction with the vapor. A selection of possible materials used to form the enclosure  230  includes various forms of stainless steel and Inconel™, such as stainless steel 316 and 316L, as indicated above, but the selection is not limited to these, provided one or more of the above characteristics can be satisfied. 
         [0018]    In another embodiment, a combination of materials may be used from which the enclosure is formed. For example, whereas the body of the enclosure  230  may be formed of one material for thermal characteristics, strength, etc., a deposited material on the interior surface may be selected for surface properties that may be beneficial. For example, the interior surface of the enclosure  230  may be electroplated with a selected material that is chemically non-reactive or non-corrosive or, alternatively, Teflon™ may be formed on the interior surface which may provide a chemically inert surface or a surface conducive to mobility and drainage of the condensed vapor, because Teflon™ has non-sticking properties. 
         [0019]    As a consequence of the arch  233  shape of the enclosure  230  also in the lower shield  232 , condensed vapor drains down an inner surface  234  of the shield  231  along the drainage gutter  245  and inwardly towards the arch  233  of the lower shield  232 , where the arch  233  is now inverted, for example, with respect to the upper shield  231 . A drain  250  coupled to a lower portion of the lower shield  232  guides the condensed vapor from the inward sloping inner surface  235  of the lower shield  232  to an exit  255  from the enclosure  230 . The drain  250  has a split structure; that is, the drain splits into two guttered drains  251  and  252 , with an aperture  254  between to permit the disc to be inserted into the enclosure  230  to be exposed to the diffuser plates  112  of the vapor source  110 , and afterwards removed. 
         [0020]    The two drains  251  and  252  are guttered to prevent condensed vapor from draining into the aperture through which the disc passes, and therefrom into the vacuum pumping system. A small narrow throat aperture  254  at a bottom of the enclosure  230  may provide for insertion and removal of the disc for the deposition process. The aperture  254  may be kept to minimum dimension to allow for insertion and removal of the disc while reducing an amount of vapor that may escape the enclosure to reach the walls of the vacuum chamber or the pumping system. The two drains  251  and  252  converged at an exit  259  coupled to a trough  260  that guides the condensed vapor downward to a reservoir  265 . 
         [0021]    The stored condensed vapor may be re-used in subsequent vapor deposition. Alternatively, the stored condensed vapor may be recycled from the reservoir  265  to the vapor source  110  for substantially immediate re-use. 
         [0022]    It is to be understood that even though numerous characteristics of various embodiments of the invention have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. For example, the particular elements may vary depending on the particular application system while maintaining substantially the same functionality without departing from the scope and spirit of the present invention. In addition, although the preferred embodiment described herein is directed to a particular set of manifolds with orifices for controlled introduction of gas into a vacuum chamber, it will be appreciated by those skilled in the art that the teachings of the present invention can be applied to other gas handling systems without departing from the scope and spirit of the present invention. 
         [0023]    The embodiments described herein thus provides a number of features not included in conventional static vapor deposition apparatus and methodology, and is of particular utility in automated manufacturing processing of thin film magnetic and MO recording media including deposition of uniform thickness lubricant topcoat layers for obtaining optimized tribological properties. Specifically, the embodiments described herein provide for recovery of lubricant and re-use of the recovered lubricant, which may result in a reduction of manufacturing costs arising from use of the lubricant. Further, the embodiments described herein can be readily utilized as part of conventional manufacturing apparatus/technology in view of their full compatibility with all other aspects of automated manufacture of magnetic and MO media. Furthermore, the embodiments described herein are broadly applicable to a variety of vapor deposition processes utilized in the manufacture of a number of different products, e.g., mechanical parts, gears, linkages, etc., using lubrication. Finally, the embodiments described herein are broadly applicable to a variety of vapor deposition processes where the ambient temperature vapor pressure is lower than the vapor pressure at elevated temperatures. 
         [0024]    The various aspects presented throughout this disclosure are provided to enable one of ordinary skill in the art to make and use the present composition. Various changes, alterations, and modifications to the compounds and apparatus presented throughout this disclosure will be readily apparent to those skilled in the art, and the concepts disclosed herein may be extended to other compounds and apparatus. Thus, the claims are not intended to be limited to the various aspects of this disclosure, but are to be accorded the full scope consistent with the language of the claims. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”