Abstract:
A device for mounting and removing a substrate from a baseplate, in particular a substrate holder assembly device, including automated features for latching and unlatching a substrate, for use in a coating mechanism, from a baseplate, which includes an adjustable snap ring holder.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present invention is a continuation in part of U.S. patent application Ser. No. 11/205,513 filed Aug. 17, 2005, which claims priority from U.S. Patent Application No. 60/603,211 filed Aug. 20, 2004 and which is a continuation in part of U.S. patent application Ser. No. 10/968,642 filed Oct. 19, 2004, all of which are incorporated herein by reference. The present invention also claims priority from U.S. Patent No. 60/826,230 filed Sep. 20, 2006, which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention relates to a device for mounting and removing a substrate from a baseplate, and in particular to a substrate holder assembly device including automated features for latching and unlatching a substrate, for use in a coating mechanism, from a baseplate, which includes an adjustable snap ring holder.  
       BACKGROUND OF THE INVENTION  
       [0003]     Conventional substrate holders  1 , illustrated in  FIG. 1 , include a baseplate  2  fastened to an annular cover  3  using screw fasteners  4 . The annular cover  3  includes an annular shoulder  6  for holding the edges of one or more substrates  7  against the baseplate  2 . A cylindrical recess  8 , or other alignment feature, is provided in the baseplate  2  for receiving a tapered pin from a mounting mechanism in a coating system, thereby providing a mating alignment feature therefor.  
         [0004]     Unfortunately, substrate holders, which utilize screw fasteners, waste valuable time during the assembly and disassembly processes, while a technician manually assembles and disassembles the annular cover from the base. Furthermore, manual manipulation of the substrate holder increases the risk of damage to the substrate holders or worse, the substrates themselves.  
         [0005]     An object of the present invention is to overcome the shortcomings of the prior art by providing an automated substrate holder assembly device, which eliminates the need for screw fasteners, and minimizes the substrate holder to human contact.  
       SUMMARY OF THE INVENTION  
       [0006]     Accordingly, the present invention relates to a substrate holder assembly device for assembling and disassembling a substrate holder of the type including a base with a detent, and a cover with a catch for engaging the detent and securing the cover to the base, comprising:  
         [0007]     a substrate holder mount for supporting the substrate holder face down;  
         [0008]     a substrate holder loading dock for supporting the substrate holder face up during assembly and disassembly;  
         [0009]     a lifting arm moveable between the substrate holder mount and the substrate holder loading dock for picking the substrate holder up, flipping the substrate holder over, and placing the substrate holder on the substrate holder loading dock; and  
         [0010]     actuator means extending from the substrate holder loading dock for disengaging the detent from the catch, thereby enabling the cover to be separated from the base, and a substrate to be loaded or unloaded from the substrate holder. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The invention will be described in greater detail with reference to the accompanying drawings which represent preferred embodiments thereof, wherein:  
         [0012]      FIG. 1  illustrates a conventional substrate holder;  
         [0013]      FIG. 2  is an isometric view of a substrate holder in accordance with the present invention;  
         [0014]      FIG. 3  is a cross-sectional view of an embodiment of the substrate holder of  FIG. 2 ;  
         [0015]      FIG. 4  is a cross-sectional view of another embodiment of the substrate holder of  FIG. 2 ;  
         [0016]      FIG. 5  is an isometric view of the substrate holder assembly device in accordance with the present invention;  
         [0017]      FIG. 6  is a side view of the substrate holder assembly device of  FIG. 5 ;  
         [0018]      FIG. 7  is an isometric view of the substrate holder assembly device of  FIG. 5 ;  
         [0019]      FIG. 8  is an isometric view of a substrate loading/unloading tool in accordance with the present invention; and  
         [0020]      FIG. 9  is a cross-sectional view of the substrate loading/unloading tool of  FIG. 8 . 
     
    
     DETAILED DESCRIPTION  
       [0021]     With reference to FIGS.  2  to  4 , a preferred substrate holder  11  in accordance with the present invention includes a generally disposable cover  12   a  ( FIG. 3 ) or a generally reusable cover  12   b  ( FIG. 4 ) mounted on a base  13 , which is preferably formed entirely or at least partially of a material that is attracted by a magnetic latch, e.g. a ferromagnetic material including one or more of iron, cobalt and nickel, as disclosed in United States Patent Publication No. 2006/0081468 published Apr. 20, 2006 to the Applicant&#39;s of the present invention. The base  13  includes a cylindrical protrusion  14  with a recess for receiving a tapered pin from the magnetic latch, and an annular mounting ring  15  forming an annular groove  20 , which will be described hereinafter. The base  13  provides a protective cover for the back side of a substrate  16 , thereby preventing unintentional and unwanted back coating. Each cover  12   a  and  12   b  includes one or more openings for substrates  16 , and defines a lip  18  extending around each opening. Each lip  18  holds an edge of a substrate  16  in a slot  19  formed in an upper face of the base  13 . The openings in the covers  12   a  and  12   b  are typically round, but could be any shape, e.g. square or oval, depending upon the shape of the substrate(s)  16 .  
         [0022]     The covers  12   a  and  12   b  also include an annular intermediate region  21  to ensure the upper face of the base  13  is covered, thereby protected from stray coating material. An annular flange  22  extends perpendicularly from the intermediate region  21  adjacent to a sidewall of the base  13  to protect the sidewall of the base  13  from stray coating material. For cover  12   a  ( FIG. 3 ), an upper and outer free edge  23   a  of the annular flange  22  is bent inwardly back around parallel with the rest of the annular flange  22  forming a catch or camming surface for engaging a latching surface  31  on the base  13 . Alternatively, one or more separate clips could extend from the cover  12   a,  perpendicular thereto, into engagement with a latching surface  31  of a detent  32 . Preferably, the clips would be made of a resilient material, e.g. the same sheet metal as the cover  12   a,  enabling the clips and the cover  12   a  to be manually released with relative ease, i.e. without the aid of tools. Various mechanical means can be provided to facilitate disengagement of the clips including levers, push buttons and rotating knobs extending therefrom.  
         [0023]     The upper or outer free edge of the annular flange  22  of the cover  12   b,  see  FIG. 4 , includes a solid annular ring  26  and an annular groove  27 . The annular ring  26  provides a catch for the detent  32 , and has a beveled corner  28  adjacent to the annular groove  27  providing a camming surface for engaging the latching surface  31 .  
         [0024]     To facilitate removal of the cover  12   a  or  12   b  from the base  13 , the latching surface  31  is disposed on the moveable detent or slide  32 , which reciprocates towards the center, e.g. radially, of the base  13 , i.e. towards cylindrical recess  14 , when a sufficient force is applied thereto. A threaded fastener  33  extends through a slot  34  in the detent  32  into the base  13  for guiding the detent  32  during reciprocation. A spring  36  extending from the back of the annular ring  15  spring biases the detent  32  outwardly, so that the latching surface  31  engages the camming surface on the catch, i.e. the outer free edges  23   a  or  23   b  of the annular flange  22 , and providing a set force, which must be overcome to release the cover  12   a  or  12   b  from the base  13 . The latching surface  31  also includes a beveled edge, at approximately the same angle as the beveled corner  28 , enabling the beveled edge of the latching surface  31  to engage the beveled corner  28  at various positions, which correspond to different substrate thicknesses. The annular groove  27  provides a sufficient gap for receiving the end of the detents  32  at various positions corresponding to different substrate thicknesses. An abutment surface  37  is provided on an end of the detent  32  opposite the latching surface  31 , and adjacent to where the spring  36  engages the detent  32 , for reasons hereinafter discussed.  
         [0025]     A typical substrate would be a glass wafer 200 mm in diameter and 0.2 mm to 1.4 mm thick; however, other substrate forms are possible, e.g. up to 32 mm in thickness and a mass of up to 2 kg.  
         [0026]     The substrate holders, illustrated in FIGS.  2  to  4 , utilize either disposable covers  12   a,  which are preferably fabricated from an inexpensive sheet metal stamping, which can be disposed of after one or two uses or reusable covers  12   b.  The covers  12   a  and  12   b  hold the substrate  16  securely and precisely relative to the base  13  during acceleration, vibration and temperature cycling. Moreover, the covers  12   a  and  12   b  shield the base  13  from stray coating flux, which would otherwise become deposited on the base  13  causing damage to the substrates  16 , if flaked off.  
         [0027]     Ideally, the covers  12   a  and  12   b  include surface characteristics on the outside, which encourage adhesion of stray coating material, and surface characteristics on the inside that facilitate easy cleaning and will not downgrade the substrate  16  when coming into contact there-with. The material or materials for covers  12   a  and  12   b  should have a low vapor pressure at coating temperatures, thereby minimizing any material released therefrom from contaminating the substrates  16  or otherwise influencing the coating process.  
         [0028]     Disposable covers  12   a  should be inexpensive, easily formable with enough resiliency to provide spring forces when appropriate, have a low vapor pressure at coating temperatures, and have minimal toxic waste issues. Ideally, the disposable covers  12   a  are between 0.005 in. and 0.015 in. thick; however, thinner covers are possible for very small substrates, i.e. up to 0.015 in is preferred. Preferably, the covers  12   a  are fabricated from electro-tinned steel (Tin Plate), which is relatively inexpensive, and easily formed. Electro-tinned steel has smooth surfaces, which can easily be cleaned The tin plating has a low vapor pressure (5.78 E-21 Pa @232.06° C.) at coating temperatures, and provides relatively good adhesion for most metals and metal oxides, whereby stray coating material will stick to the covers  12   a  rather than deflect onto the substrate  16 . For coating applications above the melting point of tin (232° C.), other sheet metals, such as aluminum and stainless steel, can be used. Surface treatments may be necessary to improve the adhesive characteristics of the outside of the cover  12   a.    
         [0029]     Reusable covers  12   b  are preferably made from aluminum or stainless steel. Aluminum can easily be machined and is of light weight, and stray coating material adheres well thereto. Roughening of the outside surface of the aluminum covers  12   b  can increases material adhesion. Care must be taken to maintain the shape and cleanliness of the substrate supporting lip  18  since aluminum is not very hard. Stainless steel is very hard and provides excellent support for the substrate  16 . The outside surface can be roughened or otherwise treaded to enhance adhesion of stray coating material.  
         [0030]     With reference to  FIGS. 5, 6  and  7 , the substrate holder assembly device, generally indicated at  41 , includes a substrate holder mount or rest section  42 , a pivot arm  43 , and a substrate holder loading dock  44  mounted on a platform  45 . The mount section  42  includes four spaced apart pedestals  46 , each having a beveled inner corner forming a beveled face  47  and a shoulder  48 . The beveled face  47  of each pedestal  46  provides a guiding surface for guiding the substrate holder  11  to a rest position on the four shoulders  48 . The illustrated mount section  42  can be replaced by any equivalent structure providing support for the substrate holder  11  during attachment to the pivot arm  42 .  
         [0031]     The pivot arm  43  is pivotally connected to the loading dock section  44  about a horizontal axis of rotation  49 , and comprises a plate  51 , extending outwardly from the axis  49 , and a handle  52  extending perpendicular to the outer free end of the plate  51 . A centering socket  53  with locking fingers  54  extends from the plate  51  proximate the middle thereof for extending into the annular ring  15 , whereby the locking fingers  54  can engage the groove  20  and secure the base  13  of the substrate holder  11  to the pivot arm  43 . The centering socket  53  receives the cylindrical protrusion  14 , when the base  13  is in proper alignment with the pivot arm  43  The actuating mechanism  55  for the locking fingers  54  extends from the plate  51  opposite the centering socket  53 .  
         [0032]     The loading dock section  44  includes a housing  56  comprised of sidewalls  57  and upper cover  58 . The upper cover  58  includes a large circular opening  59  for receiving the actuating mechanism  55  when the pivot arm  43  is pivoted into position on the loading dock section  44 . Actuators  61 , spaced apart around the opening  59 , extend through rectangular openings in the upper cover  58  for engaging the abutment surfaces  37  of the detents  32 , whereby movement, e.g. reciprocation or rotation, of the actuators  61 , indicated by arrow  62 , forces the detents  32  to reciprocate, indicated by arrow  63  in  FIG. 4 , against the biasing force of the spring  36 , thereby disengaging the latching surface  31  from the camming surface of the annular flange  22 . In the illustrated embodiment, the four actuators  61  are circumferentially spaced around the opening  59 , and each is comprised of a rectangular arm with a rectangular lip  64  extending perpendicularly from the rectangular arm for engaging the abutment surface  37 , are illustrated, but any number, arrangement and shape of the actuators  61  is possible depending on the number, position and size of the detents  32  provided on the base  13 .  
         [0033]     In use, a substrate holder  11  is carefully positioned face down on the mount section  42  and clocked, such that the detents  32  align with the actuators  61 . Ideally, the mount section  42  is provided with spaced apart indicators corresponding to the positions of the actuators  61 , which the detents  32  are aligned with, whereby when the pivot arm  43  is rotated to the loading dock section  43  the detents  32  are aligned with the actuators  61 . In the illustrated embodiment, the detents  32  are aligned with the pedestals  46  in the mount section  42 , which ensures the detents  32  will be aligned with the actuators  61  in the loading dock section  43 , i.e. the pedestals  46  themselves or the upper surface thereof act as the indicator. The beveled faces  47  of the pedestals  46  guide the substrate holder  11  until the annular flange  22  rests on the shoulders  48 . The pivot arm  43  is rotated into position on top of the substrate holder  11  with the centering socket  53  surrounding the cylindrical protrusion  14 . To secure the substrate holder  11  to the pivot arm  43 , the locking finger or fingers  54  are actuated into position within the groove  20 . The pivot arm  43  is then rotated, as illustrated by the arc in  FIGS. 5 and 6 , until the substrate holder  11  comes to rest face up on the upper cover  58  of the loading dock section  43  with the actuating mechanism  55  extending through the opening  59 . In the rest position on the loading dock section  43 , the ends of the actuators  61  extend into position proximate their respective abutment surfaces  37 . Actuation of the actuators  61  forces the detents  32  out of contact with the camming surface on the annular flange  22 , thereby releasing the cover  12   a  or  12   b  from the base  13 . Accordingly, the cover  12   a  or  12   b  and the substrate  16  can be removed from the base  13 , and a new substrate  16  and cover  12   a  or  12  can be replaced thereon. When the actuators  61  are disengaged, the detents  32  become engaged with the camming surface on the new annular flange  22 . The latching surface  31  is at an acute angle to the base  13  enabling the latching surface  31  to engage the camming surface of the annular flange  22  at a variety of positions corresponding to different substrate thicknesses. The pivot arm  43  can then be rotated back to the mount section  42 , in which the locking fingers  54  are disengaged from the groove  20 , thereby releasing the substrate holder  11  from the pivot arm  43 . The substrate holder  11  is then relocated to a suitable coating machine for application of a coating on the substrate  16 .  
         [0034]     The actuators  61 , the locking fingers  54 , and even the rotation of the pivot arm  43  can be powered, e.g. electrically and/or pneumatically, or simply manually actuated. The power supply can be controlled remotely from a single control box or from separate control locations proximate the specific device actuated, e.g. proximate the mount section  42  and proximate the loading dock section  43 .  
         [0035]     With reference to FIGS.  7  to  9 , a substrate holder removal tool  71  includes an elongated arm  72  with a first handle  73  fixed at one end thereof, and a second handle  74  fixed proximate a middle thereof. Preferably, both the first and second handles  73  and  74  include a hand grip extending perpendicular to the elongated arm  72 . A fixed bracket or wedge  76  extends from an outer free end of the elongated arm  72  for engaging the groove  20  on one side of the annular ring  15 . A sliding bracket or wedge  77  is reciprocatable on the elongated arm  72  in an area between the second handle  74  and the fixed wedge  76  for engaging the groove  20  of annular ring  15  at a position diametrically opposed to where the fixed wedge  76  engages the groove  20 . An actuating lever  78  is positioned proximate one of the first and second handles  73  and  74  for remotely actuating the sliding wedge  76  to engage or disengage the annular ring  15 . The middle of the actuating lever  78  is pivotally mounted to the elongated arm  72 , and one end of the actuating lever  78  is pivotally mounted to one end of a reciprocating link or rod  79 . The other end of the reciprocating rod  79  abuts the sliding wedge  77 , which is spring biased away from the fixed wedge  76  by spring  81 . The spring  81  is fixed to a stop shoulder  82  mounted on the elongated arm  72 . Accordingly, a force applied to the outer free end of the actuating lever  78  results in rotation thereof and reciprocation of the reciprocating rod  79  within the elongated arm  72  into engagement with the sliding wedge  77 , which overcomes the spring force of the spring  81  and forces the sliding wedge  77  towards the fixed wedge  76 . As a result, the sliding wedge  77  becomes disengaged from within the groove  20  enabling the tool  71  to be separated from the substrate holder  11 .