Abstract:
A gap set device for an electronic component handler is provided. The electronic component handler includes a test accessory mounted to it. The test accessory is movable between a first position away from a tool and a second position closer to the tool. A gap set device is mounted to the test accessory and the tool and has a portion movable with respect to the test accessory. When the test accessory is in the second position, the portion of the gap set device contacts the component support structure to define a gap between the test accessory and the component support structure.

Description:
TECHNICAL FIELD 
       [0001]    This application is a continuation of U.S. patent application Ser. No. No. 11,742,262, filed Apr. 30, 2007, which claims priority to U.S. Provisional patent application No. 60/887,126, filed Jan. 29, 2007. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates to setting a predefined and repeatable gap between an electronic component support structure and an electronic component test accessory. 
       BACKGROUND 
       [0003]    Electronic components are handled by a wide variety of different electronic component handlers. These different handlers include but are not limited to products sold by Electro Scientific Industries Inc. of Portland, Oreg., the assignee of the present patent application. Electro Scientific Industries sells a variety of electronic component handlers including, but not limited to, a high volume MLCC tester sold as the model No. 3300, a chip array tester sold as the model No. 3400, a visual test system sold as the model No. 6650, and a chip array terminator sold as the model No. 753. 
         [0004]    One such electronic component testing machine is described in prior art U.S. Pat. No. 5,842,579 entitled Electrical Circuit Component Handler. With reference to  FIG. 2 , there is shown an overall pictorial view of the electrical circuit component handler of U.S. Pat. No. 5,842,579, the entirety of which is incorporated herein by reference.  FIG. 2  illustrates a handler  10  having a plurality of test accessories thereon including a loading frame  12 , a plurality of test modules  14  and a blowoff module  16 . In operation, electronic components are passed through load frame  12  and are individually drawn into test seats  22  found on a test plate  20 . Test seats  22  typically are concentric rings that are continuous about test plate  20 . 
         [0005]    With more specific reference to loading frame  12  and with specific reference to  FIG. 2A , load frame  12  includes a plurality of arcuate fences  13 . Arcuate fences  13  allow electronic components  14  to be collected adjacent fences  13  as shown. The bases of arcuate fences  13  are slightly spaced above test plate  20  as to prevent passing or catching of electronic components beneath arcuate fences  13 . The spacing between the arcuate fences 13 and test plate  20  defines a gap labeled by the letter A. U.S. Pat. No. 5,842,579 indicates that the gap A is set by shims. 
         [0006]    Test plate  20  indexes in a direction toward test modules  14  as indicated by Arrow B as shown in  FIG. 2 . The electronic components are tested by test modules  14 . As test plate  20  continues to index the electronic components are then withdrawn from the component handler  10  by the blowoff module  16 . 
         [0007]    With continued reference to U.S. Pat. No. 5,842,579, it may be necessary to change test plate  20 . For example, test plate  20  may require changing if it becomes worn or by way of another example, test plate  20  may be changed to accommodate handling of different types of electronic components. In such situations, the test accessories, such as load frame  20 , must be moved out of the way so that the old test plate may be removed and the new test plate added. The test accessories must then be put back in place setting a proper gap between the test accessories and test plate. As described in U.S. Pat. No. 5,842,579, this gap, and in particular the gap between the load frame and the test plate, was set by using shims. The exclusive use of shims is time consuming and cumbersome. 
       SUMMARY 
       [0008]    An electronic component handler according to one embodiment comprises a component support structure received on a support surface of the handler, a test accessory mounted to the handler for movement between a first position remote from the component support structure and a second position closer to the component support structure than the first position and a gap set device mounted to the test accessory and having a portion movable with respect to the test accessory, wherein the portion of the gap set device is configured to contact the component support structure such that a gap is defined between the test accessory and the component support structure when the test accessory is in the second position. 
         [0009]    A method according to one embodiment taught herein comprises arranging a first component support structure on a support surface of an electronic component handler, after arranging the first component support structure on the support surface, moving a test accessory and a gap set device toward the first component support structure, the test accessory movable relative to the support surface and the gap set device coupled to the test accessory and having a portion movable with respect to the test accessory, such that the portion of the gap set device contacts the first component support structure and the test accessory is spaced apart from the component support structure to define a gap between the test accessory and the first component support structure, and, after defining the gap, moving the portion of the gap set device relative to the test accessory and away from the first component support structure. 
         [0010]    A method according to another embodiment comprises moving a test accessory and a gap set device away from a first component support structure disposed on a support surface of an electronic component handler, the test accessory movable relative to the support surface and the gap set device coupled to the test accessory and having a portion movable with respect to the test accessory, replacing the first component support structure with a second component support structure, after replacing the first component support structure with the second component support structure, moving the test accessory and the gap set device toward the second component support structure such that the portion of the gap set device contacts the second component support structure and the test accessory is spaced apart from the second component support structure to define a gap between the test accessory and the second component support structure, and after defining the gap, moving the portion of the gap set device relative to the test accessory and away from the second component support structure. 
         [0011]    Other applications of the present invention will become apparent to those skilled in the art when the following description is read in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
           [0013]      FIG. 1  is an exploded perspective view of a gap set device that allows a repeatable gap to be set between a load frame and a test plate; 
           [0014]      FIG. 2  illustrates a perspective drawing of a prior art electronic component handler; 
           [0015]      FIG. 2A  is a cross section of a load frame illustrating electronic component and arcuate fences; 
           [0016]      FIG. 3  illustrates a cutaway view of gap set device of  FIG. 1  taken along lines  3 - 3  in an operational position; 
           [0017]      FIG. 4  illustrates a cutaway view of the gap set device of  FIG. 1  in a different operational position; 
           [0018]      FIG. 5  illustrates a cutaway view of the gap set device of  FIG. 1  in a different operational position; 
           [0019]      FIG. 6  illustrates a cutaway view of the gap set device of  FIG. 1  in a different operational position; 
           [0020]      FIG. 6A  illustrates an alternate configuration of an air cylinder and air cylinder shaft; 
           [0021]      FIG. 7  illustrates a hollow pneumatic airshaft for use with the first preferred embodiment; and 
           [0022]      FIG. 8  illustrates an exploded reference perspective of a load frame mounting to a base plate; and 
           [0023]      FIG. 9  illustrates a kinematic adjustment to adjust the planarity of a load frame in the first preferred embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    With reference to the figures, wherein like elements are numbered alike, there is shown a gap set device for use with an electrical circuit component handler. Electronic component handlers sometimes include a moving test component, for example a test plate that holds electronic components. A stationary piece, typically a test accessory, sits adjacent the moving test component. In systems such as that described in U.S. Pat. No. 5,842,579 the gap, for example between the stationary load frame  12  and the moving test plate  20 , is set with the exclusive use of shims. Shims are difficult to handle and create a time consuming effort to set a gap. 
         [0025]    The preferred embodiments are described with reference to the electrical circuit component handler illustrated in U.S. Pat. No. 5,842,579 and in particular describe an apparatus and method used to set the gap between a load frame  12  and a test plate  20 . The present invention is not limited for use with load frames and test plates. The present invention applies equally to other electronic component handling devices, for example the devices sold by Electro Scientific Industries as model Nos. 6650, 3400 and 753. 
         [0026]    With respect to the electronic component handler of U.S. Pat. No. 5,842,579, the load frame  12  is mounted on a linear bearing. The linear bearing allows the load frame to move vertically away from the test plate such that the test plate may be replaced. A retractable setting post can extend beneath the load frame such that when the load frame is lowered back into position, by sliding the load frame down the linear bearing, the gap between the load frame fences and the test plate will be determined by the amount the setting post extends beyond the load frame fences. After the gap has been set the load frame may be locked into place and the setting post retracted out of the way. As described herein, examples of setting posts include hollow air cylinders and micrometers. 
         [0027]    With reference to  FIG. 1  there is shown an exploded perspective view of an electronic component handler utilizing a test plate  20 . Test plate  20  includes plurality of concentric test rings  22 . Electronic components are delivered into test rings  22  through the use of a load frame  12 . Load frame  12  includes a plurality of arcuate fences  13 . The arcuate fences  13  are operable to deliver electronic components  11  to an area adjacent test seats  22  as illustrated in  FIG. 2A . 
         [0028]    With continued reference to  FIG. 1 , load frame  12  is mounted to a linear bearing  30 . Linear bearing  30  includes a base  32 . As shown, base  32  is connected to a base plate  18  of handler  10  by a kinematic mount  70 . As shown, load frame  12  is slidably received into bearing  30  via a guide  34 . Guide  34  may be integral with load frame  12  or may be a separate component. 
         [0029]    As shown in  FIG. 1 , a setting post  50  is mounted to load frame  12 . Setting post  50  may be positioned in a variety of places on load frame  12 , including but not limited to guide  34 . In the first preferred embodiment, setting post  50  includes an air cylinder  52  having an extendable shaft  58 . Alternatively, the setting post  50  could be a micrometer. 
         [0030]    As shown in more detail in  FIG. 7 , air cylinder  52  includes an air inlet  54  and an air outlet  55 . Air hoses attach to each of inlet and outlet  54  and  55  to deliver air to cylinder  52  and actuate shaft  58 . The distance that shaft  58  extends from air cylinder  52  is adjustable through a collar  51 . Collar  51  includes fasteners  53  that may be loosened to allow collar  51  repositioning, thereby adjusting the distance shaft  58  extends from air cylinder  52 . As shown, shaft  58  includes an internal passage  59  through which air flows via a pneumatic coupling  56 . As described in greater detail below, as the distal end  57  of shaft  58  approaches test plate  12  the air flow through passage  59  is obstructed. This obstruction is detected and allows a gap to be set between load frame  12  and test plate  20 . 
         [0031]    With further reference to  FIG. 1 , shaft  58  is extendable beneath/beyond fences  13  of load frame  12 . With shaft  58  in its extended position load frame  12  may be lowered toward test plate  20  by linear bearing  30 . When shaft  58  comes in close proximity with test plate  20 , the airflow through the hollow portion  59  of shaft  58  is obstructed. At this point a lock  36  may be engaged to lock load frame  12  into place. As shown, lock  36  includes a knob  38  for manual actuation. An automated lock may also be used. By extending shaft  58  a known distance past the bottom of fences  13  the gap between load frame  12  and test plate  20  may be accurately and repetitiously set. In the first preferred embodiment the gap can be set to approximately  25  microns. Generally, a gap between 1 and 50 microns would be acceptable for a wide range of different electronic components. 
         [0032]    With further reference to  FIG. 1 , it may be desirable for some purchasers of the device of the first preferred embodiment to radially and axially align fences with corresponding concentric test seat rings  22 . As shown, such radial and axial alignment may be adjusted through the actuation or adjustment of micrometers  60 . As further shown in  FIG. 1 , a borescope access hole  61  may be provided to enable an operator to place a borescope, not shown, into access hole  61  to visually inspect the gap between load frame  12  and test plate  20  as well as the alignment of fences  13 . 
         [0033]    With reference to  FIG. 8 , test plate  20  is planar. Similarly, the underside of load frame  12 , and in particular the bottom edges of fences  13 , define a plane. In the preferred embodiment, kinematic mount  70  allows the plane defined by fences  13  to be adjusted to be parallel with the plane defined by test plate  12 . Kinematic mount  70  includes pins  72  located on base plate  18  of handler  10 . Pins  72  engage corresponding adjustable mounts  74  positioned on base  32 . In the first preferred embodiment, kinematic mount  70  further includes a pair of pins  76  that fit into holes  77 . Pins  76  cooperate with holes  77  to prevent base  32  from sliding on handler  10 . 
         [0034]    With reference to  FIG. 9 , the depth of each mount  74  can be changed by adjusting shaft assemblies  78 . Shaft assemblies  78  include precision adjusting knobs  79  to accomplish an adjustment of the plane defined by the underside of fences  13 . To facilitate a more precise coplanar relationship between the plane of test plate  12  and the plane defined by the underside of fences  13 , a borescope, not shown, may be placed into borescope access  61  for visual inspection. 
         [0035]    With reference to  FIGS. 3-6  there is shown a series of cutaway illustrations taken along line  3 - 3  of  FIG. 1  that illustrate a first proposed sequence of operation of the gap setting device. As shown in  FIG. 6 , load frame  12  is spaced away from test plate  20 . This allows test plate  20  to be removed from base plate  18  of handler  10 . After a replacement test plate has been mated to base plate  18 , air cylinder  52  is actuated to extend shaft  58  beyond the plane defined by fences  13  of load frame  12 . An air flow is initiated through passage  59 . As shown in  FIG. 6 , lock  36  is in an unlocked position, indicating that load frame  12  will shortly be moved in a direction toward test plate  20 . Load frame  12  may be locked by lock  36  in its upper position. 
         [0036]    With reference to  FIG. 4 , load frame  12  is moved to be adjacent to test plate  20 . Because shaft  58  extends beyond the plane defined by fences  13 , shaft  58  will come into close proximity of load frame  12  prior to fences  13 . As shaft  58  gets in close proximity with test plate  12 , the air flow through passage  59  will become obstructed. This obstructed air flow may be detected such that lock  36  may be engaged as shown by arrow  37  in  FIG. 5 . Obstruction of air flow may be indicated by a visual or audible alarm informing a user to actuate lock  36  to set the gap between test plate  12  and fences  13 . Alternatively, obstruction of air flow through passage  59  may cause an automated lock to fix the gap. 
         [0037]    With reference to  FIG. 3 , it is shown that after the gap has been set by setting post  50  and shaft  58 , air cylinder  52  is actuated to retract setting post. Retraction of setting post  50  allows test plate  20  to freely rotate without obstruction from shaft  20 . 
         [0038]    With reference to  FIG. 6A , there is shown an alternate configuration of an air cylinder and air cylinder shaft. As shown in  FIG. 6A , shaft  158  includes a shoulder  159 . When air cylinder  152  engages shaft  158  to its fullest extent, shoulder  159  will engage a flange  161  machined internally into load frame  12 . By setting the location of flange  161 , the distance that shaft  158  protrudes beyond fences  13  may be fixed. The location of flange  161  may be set by precisely machining load frame  12  or in the alternative flange  161  may be raised or lowered by use of shims. The shims used to raise or lower flange  161  would not have to be replaced each time test plate  20  is replaced insofar as the shims would merely fix the distance shaft  158  protruded beyond fences  13 . 
         [0039]    While the invention has been described in connection with certain embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.