Patent Publication Number: US-2002003994-A1

Title: Component source interchange gantry

Description:
CROSS REFERENCE  
     [0001] The following related patents and co-pending applications are hereby incorporated by reference for their teachings: p 1  “WAFER INTERCHANGE GANTRY,” a U.S. Provisional Application for Patent by P. Davis et al.,  60 / 216 , 855 , filed Jul.  7 ,  2000 ;  
     [0002] “METHOD AND APPARATUS FOR REMOVING DIE FROM AN EXPANDED WAFER AND CONVEYING DIE TO A PICKUP LOCATION,” Peter Davis et al., U.S. Pat. No. 5,976,306, issued Nov. 2,1999;  
     [0003] “METHOD AND APPARATUS FOR REMOVING DIE FROM A WAFER AND CONVEYING DIE TO A PICKUP LOCATION,” by Peter Davis et al., U.S. application No. 09/251,541, filed Feb. 17,1999. (HD-DDF-3); “METHOD AND APPARATUS FOR REMOVING DIE FROM A WAFER AND CONVEYING DIE TO A PICKUP LOCATION,” by Peter Davis et al., WO/99/42289 (PCT-US99/03385), filed Feb. 17,1999;  
     [0004] “DIE SHUTTLE CONVEYOR AND NEST THEREFOR,” by Peter Davis et al., U.S. patent application No. 09/684,189, filed Oct. 6, 2000 (formerly U.S. Provisional Application No. 60/158,413, filed Oct. 7,1999); and  
     [0005] “SELF-THREADING COMPONENT TAPE FEEDER,” by David W. Lyndaker et al., Provisional Application No. 60/293,397, filed May 24, 2001. 
    
    
     
       [0006] This invention relates generally to an apparatus for automatically replenishing a component source in an automated component feeder such as a surface mount die source, and more particularly to a gantry-type apparatus for storing and automatically delivering a plurality of components to a component feeder.  
       BACKGROUND AND SUMMARY OF THE INVENTION  
       [0007] The present invention is a component source interchange gantry designed to automatically store and replenish semiconductor components stored on both wafers used in a direct die feeder such as the Hover-Davis Direct Die Feeder (DDF), or in component tape reels employed with component tape feeders such as the SELF-THREADING COMPONENT TAPE FEEDER (60/293,397) noted above. In the mass production of printed circuit boards automated pick-and-place equipment generally accept die from a tape and reel feeder and/or waffle tray method and subsequently places them at a predetermined location on the circuit board or similar substrate. The direct die feeder or DDF is capable of performing this function of presenting die directly from a wafer without taking up significantly more space than a tape feeder. By reducing the handling of bare die on its journey from wafer to assembly, significant cost reduction is realized, and the limited handling mitigates the potential for damage to the individual die, thereby enhancing the reliability of the end product.  
       [0008] However, the supply of die to a DDF, via expanded wafers holding the die, currently requires human intervention, where a technician or machine operator is responsible for removing a depleted wafer frame, and replenishing the feeder with a new or full wafer. Such a process not only requires labor, but may also result in additional operation costs if the pick-and-place equipment must be shut down or idled during the replacement of a wafer. Accordingly, the present invention is directed to an apparatus that can preferably store and automatically replenish spent wafers so as to avoid the need for operator intervention and to reduce wafer interchange time and handling. It will be further appreciated that similar benefits may be achieved in conventional component tape feeders were a similar system adapted to automatically supply component tape reels to self-threading or auto-loading component tape feeders.  
       [0009] In accordance with the present invention, there is provided an apparatus for supplying component storage units to a component feeder, comprising: a frame for positioning the apparatus in juxtaposition with the component feeder; a storage bay located within the confines of said frame for storing a plurality of component storage units therein; a gripper assembly for gripping one of the plurality of component storage units stored in said storage bay; and gripper assembly movement means for automatically moving the gripper assembly from a position adjacent the storage bay to a position adjacent the component feeder.  
       [0010] In accordance with another aspect of the present invention, there is provided an apparatus for supplying wafers to a direct die feeder, comprising: a frame for positioning the apparatus in juxtaposition with a direct die feeder; a wafer bay located within the confines of said frame for storing a plurality of wafers therein; a gripper assembly for gripping one of the plurality of expandable wafers stored in the wafer bay; and gripper assembly movement means for moving the gripper assembly from a position adjacent the wafer bay to a position adjacent the direct die feeder.  
       [0011] In accordance with yet another aspect of the present invention, there is provided a method for automatically supplying components to a component feeder, comprising the steps of: positioning a collection of component storage units in a bay in juxtaposition with a component feeder; releasably gripping a component storage unit in the bay; and moving the component storage unit from a position within the bay to a position adjacent the component feeder to facilitate the automatic insertion of the component storage unit into the feeder for use.  
       [0012] In accordance with a further aspect of the present invention, there is provided a method for automatically supplying wafers to a direct die feeder, comprising the steps of: positioning a collection of wafers in a wafer bay in juxtaposition with a direct die feeder; releasably gripping a wafer stored in the wafer bay; and moving the wafer from a position adjacent the wafer bay to a position adjacent the direct die feeder to facilitate the automatic insertion of the die into the feeder for use.  
       [0013] One aspect of the invention is based on the discovery of techniques for automatically gripping and transporting wafers and component tape reels from a storage bay to a component feeder such as a direct die feeder. For example, a gantry-type system for providing wafers to a direct die feeder in a surface mount assembly system. The techniques implement a robotic or automated feeding operation in order to handle the wafers in a careful and controlled manners so as to retrieve empty wafer frames and replenish the direct die feeder thereby limiting operator intervention. Moreover, the storage bay of the system may include positioning systems for interchangeable wafer or reel magazines, as well as pre- or post-processing functions.  
       [0014] The technique described above is advantageous because it is efficient compared to manual, labor-intensive approaches. The techniques of the invention are advantageous because they provide a range of alternatives for the fetch and retrieval of components (on wafers or reels) to re-supply the component feeder, each of which is useful in appropriate situations. As a result of the invention, longer term, automated operation of component feeders will be possible. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0015]FIGS. 1 and 2 are perspective views of an embodiment of the component interchange gantry system in a closed and an open position, respectively, in accordance with an aspect of the present invention;  
     [0016]FIG. 3 is a perspective view of a portion of an alternative embodiment of the component interchange gantry system for use with tape reel component feeders;  
     [0017]FIG. 4 is a detailed view of components of the system of FIG. 1;  
     [0018]FIG. 5 is a detailed view of a gripper assembly of the system of FIG. 1 with a wafer held therein;  
     [0019]FIG. 6 is a schematic block diagram illustrating various components of a component interchange gantry system in accordance with the present invention; and  
     [0020]FIG. 7 is a flow chart depicting the various steps in the automated process executed in accordance with an embodiment of the present invention. 
    
    
     [0021] The present invention will be described in connection with a preferred embodiment, however, it will be understood that there is no intent to limit the invention to the embodiment described. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.  
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0022] For a general understanding of the present invention, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to designate identical elements.  
     [0023]FIG. 1 depicts a perspective view of an embodiment of the component source interchange gantry  100  in an operating position as it may be configured for use as a supply of wafers for a direct die feeder. FIG. 2 depicts the same component source interchange gantry in an “open” position where it would allow access to an associated component feeder  130 . Referring to FIGS. 1 and 2, frame support members  102  and  104  are intended to be integrally affixed to the frame or structure of a component pick-and-place assembly system (not shown). Frame member  102  preferably includes pivot axis  1   10  and  112  about which the storage bay and gantry frame  114  is hingedly affixed to the member  102 . In one embodiment, the pivots provide a means for moving said gripper and gantry assembly away from the component feeder. On the opposite support member  104 , the frame  114  is supported, when in a “closed” position, by support member  106  that rotateably interferes with and supports the bottom of frame  114  when it is moved to a position adjacent frame member  104 . Although not shown, it is also possible that gantry frame  114  may employ casters or other support mechanisms to support the frame when it is an opened position.  
     [0024] As an alternative means for moving the gripper assembly and gantry frame  114  away from the component feeder, it is further contemplated that the assemblies may be accurately positioned and moved via a linear mechanism such as a slide or rail-type device (manual or automated), so as to provide access to the component feeders there below. More specifically, the mechanism may slide in either an outward or an upward direction so as to provide access to the feeders. It will be further appreciated that a slide or rail system, to provide such access, may require hardware not currently reflected in FIG. 2.  
     [0025] The component source interchange gantry includes a component source storage bay  116  for storing a plurality of component storage units that have a plurality of components associated therewith (e.g., wafers or component tape reels) therein. Within the gantry frame  114 , and particularly within component source storage bay  116 , a plurality of expandable (or unexpanded) wafers such as those disclosed and taught in U.S. Pat. No. 5,976,306, previously incorporated by reference, are stored. In particular, a component storage unit such as a wafer ring  140  is preferably held in a wafer frame  142 , the wafer frame being suitable for storing the wafer (or more appropriately the die divided therefrom) in a rack or magazine  118  within the wafer bay. Preferably the magazine is comprised of parallel grooves or slots positioned along the top and bottom thereof, and is slidably mounted within component source bay  116  so the wafer ring(s) and frame(s) are preferably held in a vertical or upright position, such as a Wafer Frame Magazine made by Perfection Products, Inc. (Model # FFM- 4263 - 01 ) and preferably able to hold approximately twelve expanded wafer frames therein.  
     [0026] It will be appreciated that other regions within bay  116  may also be used for the staging of wafers awaiting loading as well as used or depleted wafer frames. Moreover, the other regions within bay  116 , for example regions  117  and  119  may also be used for pre- or post-processing of wafers in conjunction with an aspect of the present invention. For pre-processing, it is contemplated that a region within the bay may be employed to provide a wafer-expansion capability within the bay and prior to positioning the wafer in the feeder. Similarly, one of the regions within bay  116  may include an ultraviolet (UV) light exposure station, where a wafer is inserted into the station prior to being loaded into one of the die feeders  130 . Another possible pre-processing station would be a mapping station where the wafer may be scanned for missing or damaged die, or to confirm the presence of indicators (ink dots) on known bad die (KBD). Examples of post-processing operations, in addition to storage, may be a station to remove the expanding rings from the spent wafer frame for subsequent reuse on the next wafer within the wafer expansion queue. And lastly yet another functional application within the storage bay region would be the ability to read specific encoded data, which references the actual component via a part number and unique batch ID. The decoding means most generally employs the optical imaging of bar codes however OCR and magnetics (e.g., magnetic ink character recognition) are acceptable alternatives. The decoding and subsequent verification process can be exercised upon the loading of new components into the bay as well as just prior to transporting the components into the feeder.  
     [0027] As previously noted, and as depicted in FIG. 3, it is further contemplated that in the place of a plurality of wafers stored in bay  116 , a plurality of component storage units such as tape reels  122  may be stored. In particular such a system may be used for the automated reloading of a self-threading component tape type feeder such as that described in a co-pending U.S. Provisional Application No. 60/293,397 for a “SELF-THREADING COMPONENT TAPE FEEDER” by Lyndaker et al., previously incorporated by reference.  
     [0028] Also depicted in FIGS. 1 and 2 is a gripper assembly  150  for gripping one of the plurality of wafer frames  142  or component tape reels  122  stored in bay  116 . The gripper assembly is moved from a position adjacent the storage bay to a position adjacent the component feeder  130  via gripper assembly movement means  124  that includes a plurality of translatable slides, and drive mechanisms associated therewith, positioned along at least two and preferably three axes (X, Y and Z as shown in the figures).  
     [0029]FIG. 1 further depicts a user-interface display  132  associated with the system  100 . Preferably, the display  132  is a touch-screen type display (displays an image and is responsive to a user&#39;s touching of the display screen) that may be used in conjunction with the interchange system, and its control logic and circuitry (FIG. 6) to support one or more of the following features/functions:  
     [0030] (a) Teaching and calibration of the interchange system as well as the feeding apparatus can be controlled via icons on the screen;  
     [0031] (b) Communicate status or errors to a user via the display screen;  
     [0032] (c) Video output from the component feeder may be directed to the touch screen in lieu of an on-board viewer;  
     [0033] (d) Provide on-line documentation such as a service and/or an Operator&#39;s Manual;  
     [0034] (e) Provide a diagnostics interface for troubleshooting the system;  
     [0035] (f) Provide an operator interface during operation of the system.  
     [0036] It is further contemplated that the component source interchange system may be interconnected or networked with the component feeders and/or the printed circuit board assembly systems they support, where the display  132  may be adapted to display data or other information associated with other systems and components in communication with the component source interchange system  100 .  
     [0037] Referring next to FIGS. 1 and 4, the process for moving the gripper assembly  150  relative to bay  116  and component feeder  130  involves the activation of the drive mechanism for at least one axis and possibly multiple axes concurrently. Motion along the X-axis is regulated by a pair of slides or rails  160 , wherein a carriage  162 , to which gripper assembly  150  is attached, is moved under the control of a linear actuator such as a screw-type drive  162 , driven by a drive motor  166  operatively associated with the screw drive via a belt  168  and pulley assembly  170 . Rotation of the drive motor  166  results in the rotation of the screw drive and the displacement of carriage  162  along the slides  160 . As will be described below, operation of the drive is controlled as a function of the position of the carriage, such position being monitored in accordance with the engagement of the drive motor. If a stepper motor is employed as the drive motor, it may be possible to accurately control the X-axis motion without the need for real time position sensing feedback.  
     [0038] Similarly, the motion of the gripper assembly relative to the Y-axis is controlled by a linear slide  176 . However, for this direction the position of a carriage  178  along the slide is controlled by the movement of a drive belt  180  operatively affixed to the carriage. Drive belt  180  is, in turn, driven in response to the rotation of pulley assembly  182  operatively coupled to drive motor  184 .  
     [0039] Lastly, the Z-axis motion of the gripper assembly  150  is controlled by a linear slide  190  oriented in a direction parallel to the Z-axis. A carriage  192  is slidably coupled to the Z-axis linear slide as well as a drive belt  194 . As with the Y-axis drive mechanism, a drive motor  196 , and pulley assembly  198  operatively coupled thereto, are employed to control the movement of drive belt  194 . Here again, stepper, servo, linear or similarly controlled motors may be employed to accurately position each of the slides along the associated slides or rails, thereby controlling the ultimate position of gripper assembly  150  in three directions.  
     [0040] Control and logic circuitry, including a stepper motor controller  280  (FIG. 6) are contained within housing  200 , which is operatively connected to frame  114 . Control of system  100  is preferably accomplished using a general purpose programmable controller  260  (FIG. 6) equipped with multiple i/o ports for sending and receiving from the various sensors and motion control devices As a result of the control circuitry a gripper assembly  150 , with a wafer frame  142  grasped therein, may be moved in a generally continuous fashion from a position adjacent the storage bay  116 , where a wafer frame is extracted from the storage magazine, to a position in proximity to the component feeder (load location) where the wafer frame may be automatically inserted into the feeder  130  for use.  
     [0041] Those skilled in the art of robotic equipment design will appreciate that there are numerous alternative configurations for the gripper assembly movement means, including single-arm robots and other mechanisms to reliably and accurately position the wafer gripper assembly relative to the storage bay  1   16  and the feeder(s)  130 . It will be further appreciated that various shields and covers may be placed on the gantry apparatus during operation so as to shield the wafers and die from dust, and to prevent the apparatus from being tampered or interfered with during operation. Such covers may further provide safety protection by preventing operators from contact with the moving gripper assembly and other components of the component source interchange gantry  100 . It is further contemplated that the covers and shield may be an integral part of the gantry frame  114 , and that one or more of such covers and shield may employ casters or wheels so as to provide support to the gantry frame during use or when the gantry frame is in an opened state.  
     [0042] Turning now to FIG. 5, there is depicted an illustration of the various components of the gripper assembly  150 . The gripper assembly includes a mount  206  for attaching the gripper assembly to the gripper assembly movement means, preferably a carriage that travels along a linear slide as described above. Mount  206 , as depicted in the figure, includes a magnetic coupling surface  208  that, during operation of the system, is coupled to an opposing surface on the bottom of the Yaxis carriage  178  (FIG. 4). One or more alignment pins  210  achieve alignment of the mount  206  with the carriage  178 , and corresponding receptacles on the opposing surface (not shown). The magnetic coupling is preferably a permanent magnet, and provides a breakaway mount should the gripper assembly come into contact or interference with another piece of equipment. Furthermore, tether  174  in FIG. 4 is included to prevent the mount and gripper assembly from falling to the floor beneath the system in the event they mount is decoupled.  
     [0043] Assembly  150  further includes opposing clamping members  214  and  218  that are pivotably attached to one another by hinge  222 . The clamping members are biased against one another by a plurality of springs  224  along the rear edge of members  218 . Under the control of pneumatically operated actuators  230  and  234 , the separation of the members  214  and  218  is controlled. It will be appreciated that in order to control the position of the clamping members relative to one another, it is preferable that actuators  230  and  234  are positioned on the opposite side of the hinge from the springs  224 . Furthermore one or more sensors  238  (optical or manual switch type) may be employed in conjunction with the clamping members  214  and  218  to determine or verify the presence and position of a wafer frame or component tape reel when one is to be retrieved by “closing” members  214  and  218  of the gripping assembly  150 .  
     [0044] Referring briefly, to FIG. 6, there is illustrated a general schematic diagram showing the control circuitry for system  100 . In particular, a system controller  260  receives input from a plurality of sensors such as door sensors  264 , from the touch screen user interface display  132 , and from the host machine (input line  268 —e.g., Ethernet or a similar network protocol). In response to a set or pre-programmed instructions and the various inputs or programmatic variables, system controller  260  operates the component source interchange gantry system. Operation of the system includes not only the control and monitoring of the gantry drives (drive controller  280  and drives  166 , 184  and  196 ), but also of the system pneumatics such as the pneumatic wafer gripper (block  150 , having actuators  230  and  234  as depicted in FIG. 5) and optional pre- or post-processing equipment  272  in bay  116  (not shown). Accordingly, system  100  is provided as a turnkey system that may be fully integrated with new or existing assembly systems and associated component feeders.  
     [0045] Referring again to FIG. 2, the details of latch mechanism  120  will be discussed. Latch  120 , as shown, may be an electromagnetic latch, wherein the application of power to the electromagnets within the latch cause the latch to remain coupled to a magnetic surface such as surface  121  positioned on frame  102  directly opposite the magnetic latch. Alternative latching mechanisms such as a catch or clasping mechanism may be employed, so long as the mechanism serves to assure that both of the pivot points ( 110  and  112 ) are completely closed in order for the latch to engage. The required functionality of latch  120  may be provided by a pneumatically actuated latch, whereby the latching mechanism is pneumatically operated via an actuator and an associated valve assembly (not shown). Furthermore, latch  120  may include an associated switch or sensor, wherein a failure to latch, unlocking or opening of the latch, will disable the system from automated operation. Such a feature is believed to be a safety feature that will not only prevent possible injury to a user, but will also prevent the unintended damage of system components were the system to be operated when the gantry and bay assemblies are open.  
     [0046] Referring lastly to FIG. 7, there is depicted a basic flow diagram illustrating the various general steps accomplished by the present invention in an embodiment where it is configured to operate with one or more direct die feeders (DDF). Beginning with Step  300 , the system receives a signal from the DDF that the current wafer has been exhausted of die. After receiving the signal, the gripper assembly is moved to a position adjacent the DDF load position, step  304 , where the gripper is able to retrieve the exhausted wafer, step  308 . Once the gripper has gripped and retrieved the exhausted wafer at step  308 , as verified by a wafer frame sensor on the gripper (not shown), the gripper assembly is moved using the X-Y-Z axes (step  312 ) to a position where the wafer frame can be deposited in an open slot in the wafer bay, step  316 .  
     [0047] Having retrieved and deposited the exhausted wafer frame, the gripper assembly next moves to a full wafer slot in the bay, step  320 , and grips the wafer frame so as to extract the full wafer frame from the bay, step  324 . Subsequently, the gripper assembly is moved, again via the X-Y-Z axes to a position adjacent the DDF load position, step  328 . The full wafer frame is deposited into the DDF, step  332 , and the component source interchange gantry system automatically sends a signal to the DDF (and/or the host machine) indicating that a new wafer is available and then waits for a signal that another fetch and retrieve cycle is necessary, step  336 .  
     [0048] In recapitulation, the present invention is a method and apparatus for automatically storing and replenishing a source of components (e.g., expandable wafers used in a direct die feeder such as the Hover-Davis Direct Die Feeder and component tape reels). In the mass production of printed circuit boards automated pick-and-place equipment accepts die from “chip” or component feeders and then mounts them at a predetermined location on the circuit board. The present invention includes a storage bay and a gripping assembly that is moved by a gantry robot to retrieve a wafer or reel from the storage bay and automatically deposit the wafer into a component feeder.  
     [0049] It is, therefore, apparent that there has been provided, in accordance with the present invention, a method and apparatus for storing and automatically replenishing a component source in association with a component feeding system. While this invention has been described in conjunction with preferred embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.