Abstract:
A vacuum collet includes at least one weight disposed in the collet for assisting in removal of components from the collet. The weights are movable within the collet to gently dislodge components lodged on a bottom face of the collet. The weights may be actuated by the same vacuum which draws components to the collet.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a vacuum collet for handling small components. 
     DESCRIPTION OF THE RELATED ART 
     During the production of certain semiconductor devices, it is often necessary to handle very small components. These components must be picked up and placed on the semiconductor devices accurately to ensure proper performance of the semiconductor devices. Currently, small components which are placed on semiconductor devices are picked and placed using an automated vacuum collet device. The collet device picks up the components from a production area, moves them to an area where the semiconductor devices are located, and places the components on the semiconductor devices. Examples of components transferred using a vacuum collet are laser bars and laser chips. Laser bars are elongate portions of laser material typically formed by cleaving a laser wafer. Laser chips are smaller portions of the laser bars, formed by cleaving the laser bar into small sections. Laser chips are used in semiconductor devices such as, for example, optical subassemblies (OSAs). An OSA uses the laser chip to project a laser beam towards a spherical lens which focuses the beam. When producing OSAs, both laser bars and laser chips must be accurately handled. The laser bars must be moved from an area where they are produced to an area where they are cleaved into a plurality of laser chips. The laser chips must then be moved from the area where they are produced to the surface of a substrate which forms the OSA. Currently, the picking and placing of the laser bars and laser chips is accomplished using a vacuum collet device. FIGS.  1 ( a ) and  1 ( b ) show a conventional vacuum collet device  10  including a vacuum collet  20  and an associated component  40  (e.g. laser bar, laser chip). The collet device  10  also includes a vacuum source  30  through which a vacuum is applied to the collet  20 . FIG.  1 ( a ) shows the collet  20  with no vacuum applied, and FIG.  1 ( b ) shows the vacuum collet  20  with vacuum applied. The vacuum created within the collet  20  draws the component  40  toward a bottom surface  21  of the collet and holds the component there as long as the vacuum remains applied. When the vacuum is deactivated, the component  40  sometimes falls away from the bottom face  21  of the collet  20  on its own. Often, however, the component  40  remains stuck to the bottom face  21  of the collet  20 . When this occurs, an operator must either remove the component  40  manually or activate a gas puff through the collet  20 , in the direction opposite of the vacuum, which forces the component  20  away from the collet. The mechanism for producing the gas puff is not shown in FIGS.  1 ( a ) and ( b ), however, it would typically be connected to the collet  20  through the same line as the vacuum. Removal of the components  20  manually can be very time-consuming. Further, removal by a gas puff has not always proven effective. The force of the gas puff often upsets other components in the area where the component being transferred is being placed. 
     Thus, there exists a need for a vacuum collet which allows easy and efficient removal of components from the collet. 
     SUMMARY OF THE INVENTION 
     The present invention is an apparatus for handling components which includes a vacuum tool and at least one weight disposed within the vacuum tool. The weight is movable within the vacuum tool to remove components from a face of the vacuum tool. 
     The above and other advantages and features of the present invention will be better understood from the following detailed description of the preferred embodiments of the invention which is provided in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG.  1 ( a ) shows a conventional vacuum collet prior to picking up a laser component. 
     FIG.  1 ( b ) shows the vacuum collet of FIG.  1 ( a ) after picking up a laser component. 
     FIG.  2 ( a ) shows a vacuum collet according to a first embodiment of the present invention with a laser component attached thereto. 
     FIG.  2 ( b ) shows the vacuum collet of FIG.  2 ( a ) with the laser component being removed. 
     FIG.  3 ( a ) shows a vacuum collet according to a second embodiment of the present invention with a laser component attached thereto. 
     FIG.  3 ( b ) shows the vacuum collet of FIG.  3 ( a ) with the laser component being removed. 
     FIG.  4 ( a ) shows a vacuum collet according to a third embodiment of the present invention with a laser component attached thereto. 
     FIG.  4 ( b ) shows the vacuum collet of FIG.  4 ( a ) with the laser component being removed. 
     FIG.  5 ( a ) shows a vacuum collet according to a fourth embodiment of the present invention with a laser component attached thereto. 
     FIG.  5 ( b ) shows the vacuum collet of FIG.  5 ( a ) with the laser component being removed. 
     FIG.  6 ( a ) shows a side elevation view of the vacuum collets shown in FIGS.  3 ( a )- 5 ( b ). 
     FIG.  6 ( b ) is a bottom view of the vacuum collets shown in FIGS.  3 ( a )- 5 ( b ). 
    
    
     DETAILED DESCRIPTION 
     Referring to FIGS.  2 ( a ) and  2 ( b ), there is shown a vacuum collet device  100  according to a first exemplary embodiment of the present invention. The collet device  100  includes a vacuum collet tube  110  with a first vacuum hole  113  and a first chamber or bore  114  coupled to the vacuum hole. The collet device  100  also includes second and third vacuum holes  115 ,  116  with second and third chambers or bores  117 ,  118  coupled respectively thereto. The first through third bores  114 ,  117 ,  118  are preferably passages of tubular shape with a circular cross-section, however, they may be formed in any suitable shape without departing from the scope of the invention. The second and third bores  117 ,  118  are coupled to the first bore  114  by openings  119  formed in the collet  110 . The openings  119  are also preferably of tubular shape with circular cross section, however, they may be formed in any suitable shape without departing from the scope of the invention. The width of the openings  119  is such that air may flow through, but weights  130 ,  131  (described below) cannot pass into the bore  114 . The collet  110  is coupled, at its top portion  111 , to a vacuum source  120 . The vacuum source  120  provides a vacuum to the collet  110  which draws components  140  toward a bottom face  112  of the collet. The collet  110  also includes weights  130 ,  131  disposed in each of the second and third bores  117 ,  118  of the collet for removing components  140  from the bottom face  112  of the collet  110 . As shown in FIGS.  2 ( a ) and  2 ( b ), the weights  130 ,  131  are moved upward in the collet  110  when the vacuum is activated. In order for the weights  130 ,  131  to be lifted away from the component  140 , there must be a pressure differential between the areas above and below the weights. This pressure differential can be accomplished by introducing openings  132 ,  133  at the bottom face of the collet  110 . The width of the openings  132 ,  133  will determine the pressure differential and how far the weights  130 ,  131  are raised above the component  140  being handled. Shutting off the vacuum (i.e. equalizing the pressure differential) causes the weights  130 ,  131  to drop, and release the component  140 . It should be noted that although the openings  132 ,  133  are disposed in the bottom face  112  of the collet  110  in the exemplary embodiment, they may be disposed at any position along the collet so that a pressure differential is created in the areas above and below the weights  130 ,  131 . The weights  130 ,  131  may be made of metal, plastic or any other suitable material known to those skilled in the art. Although the weights  130 ,  131  are shown as being substantially spherical in FIGS.  2 ( a ) and  2 ( b ), they may be formed in any suitable shape which allows them to move within the second and third bores  117 ,  118 . For example, utilizing tubular bores  117 ,  118  with circular cross-section, the weights  130 ,  131  could also be made in the shape of a cylinder. Alternately, if the bores  117 ,  118  were made tubular with a rectangular cross section, rectangular or square weights  130 ,  131  would work equally as well. There are many variations in the shape of the bores  117 ,  118  and the corresponding shape of the weights  130 ,  131  which are too numerous to mention here. These alternative shapes are also contemplated within the scope of the invention. 
     Preferably, the diameters of the vacuum holes  115 ,  116  and openings  119  of the collet  110  are less than the diameter of the weights  130 ,  131 , so that the weights do not exit into the first bore  114  or out of the bottom face  112  of the collet  110  during operation. The weights  130 ,  131  are movable, by action of the vacuum source  120 , between a position where they are completely encased inside the collet  110 , and a position where a portion thereof extends outside the collet. FIG.  2 ( a ) shows the vacuum activated and the weights retracted into the upper portion of the respective portions  117 ,  118 , so that the component  140  is drawn against the bottom face  112  of the collet  110 . FIG.  2 ( b ) shows the collet  110  after the vacuum has been deactivated and the weights  130 ,  131  have fallen to the vacuum holes  115 ,  116  at the bottom of the respective portions  117 ,  118  of the collet  110 . The operation of the vacuum collet device  100  is explained in more detail below. 
     When handling components  140  (e.g. laser bars, laser chips) using the collet device  100  according to the first exemplary embodiment of the present invention, the collet  110  is placed over the components to begin the process. In order to move the components  140  from one location to another, the vacuum source  120  is activated creating a vacuum at the bottom face  112  of the collet  110 . This vacuum draws the components  140  toward the bottom face  112  of the collet  110  and retains them there. The activation of the vacuum also draws the weights  130 ,  131  upwardly in second and third bores  117 ,  118  towards the openings  119 . The weights  130 ,  131  move up in the bores  117 ,  118  until they reach the top of the portions and are held there as long as the vacuum is activated. The entire collet device  100  is then moved (on a swing arm or similar device; not shown) to the position where the components  140  are to be placed. The vacuum source  120  is then deactivated, thereby restoring ambient pressure at the bottom face  112  of the collet  110 . As soon as the vacuum is deactivated, the weights  130 ,  131  move downwardly in the collet  110  (due to gravity) and contact the component  140 , thereby forcing the component away from the bottom face  112  of the collet  110 . The weights  130 ,  131  are made so that they are heavy enough to gently remove the components  140  from the bottom face  112  of the collet  110 , but not so heavy so as to damage the components. Instead of the bores  114 ,  117 , and  118 , the vacuum collet may include a screen, which may be in the form of a plate, a mesh, or a frame, as described in detail below. 
     FIGS.  3 ( a ) and  3 ( b ) show a collet device  200  according to a second exemplary embodiment of the present invention. As opposed to the collet device  100  according to the first embodiment, the collet device  200  according to the second embodiment includes only one vacuum hole  213  and one bore  214  coupled to the vacuum hole. A single weight  230  is disposed in the bore  213  of the vacuum collet  210  for removing components  140  from the bottom face  212  of the collet. The collet  210  also includes notches  232 ,  233  for creating a pressure differential (see FIGS.  6 ( a ) and  6 ( b )). The process for creating the pressure differential is explained above with reference to FIGS.  2 ( a ) and  2 ( b ) and elements  132 ,  133 . The weight  230  is prevented from upward movement in the bore  214  by a plate  250 . The plate  250  preferably extends across the entire diameter of the bore  214 . The plate  250  includes a plurality of holes  251  which are of a diameter less then the diameter of the weight  230 . The holes  251  allow air to pass through the plate  250 , but prevent the weight from passing through. The plate  250  is preferably made of metal or plastic, but may be made of any suitable material without. departing from the scope of the invention. The collet  210  is coupled, at its top portion  211 , to a vacuum source  220 . The vacuum source  220  provides a vacuum to the collet  210  which draws components  240  toward a bottom face  212  of the collet. The vacuum also causes the weight  230  disposed in the collet  210  to move from a position in a lower portion of the collet to a position in an upper portion of the collet. FIG.  3 ( a ) shows the weight  230  retracted and the vacuum activated, so that the component  240  adheres to the bottom face  212  of the collet  210 . FIG.  3 ( b ) shows the collet  210  after the vacuum has been deactivated and the weight  230  has fallen to the bottom of the collet  210 . When the weight  230  is disposed in the lower portion of the collet  210 , as shown in FIG.  3 ( b ), the weight operates to remove the component  240  from the bottom face of the collet. In particular, when the vacuum is deactivated and the weight  230  falls towards the bottom face  212  of the collet  210 , a portion thereof contacts the component  240  attached to the bottom face. The contact of the weight  230  with the component  240  forces the component away from the bottom face  212  of the collet  210 . 
     FIGS.  4 ( a ) and  4 ( b ) show a collet device  300  according to third exemplary embodiment of the present invention. The collet device  300  is substantially similar to the collet device  200  shown in FIGS.  2 ( a ) and  2 ( b ), and like reference numerals indicate like elements. The collet device  300  preferably includes notches  332 ,  333  for creating a pressure differential (see FIGS.  6 ( a ) and  6 ( b )). The collet device  300  differs from the collet device  200  in that it includes a wire mesh screen  350 . The mesh  350  prevents the weight  330  from moving past it in the bore  314 . The mesh may be formed of metal or plastic or any other suitable material known to those skilled in the art. The operation of the collet device  300  is substantially similar to the operation of the collet device  200 . FIG.  4 ( a ) shows the collet device  300  with the weight  330  retracted and the vacuum activated, so that the component  340  adheres to the bottom face  312  of the collet  310 . FIG.  4 ( b ) shows the collet device  300  after the vacuum has been deactivated and the weight  330  has fallen to the bottom of the collet  310 . 
     FIGS.  5 ( a ) and  5 ( b ) show a collet device  400  according to fourth exemplary embodiment of the present invention. The collet device  400  is substantially similar to the collet device  200  shown in FIGS.  2 ( a ) and  2 ( b ), and like reference numerals indicate like elements. The collet device  400  preferably includes notches  432 ,  433  for creating a pressure differential (see FIGS.  6 ( a ) and  6 ( b )). The collet device  400  differs from the collet device  200  in that it includes a frame which may be in the form of a tripod  450 . The frame  450  prevents the weight  430  from moving past the frame in the bore  414 . The exemplary tripod frame  450  includes three legs which may be substantially identical. The legs  451  protrude into the center of the bore  414  of the collet  410  where they are coupled to one another. The legs  451  of the frame are made wide enough (or spaced sufficiently close together) so that the weight  430  cannot pass through spaces between the legs. The frame  450  may be formed by metal or plastic or any other suitable material known to those skilled in the art. The operation of the collet device  400  is substantially similar to the operation of the collet device  200 . FIG.  5 ( a ) shows the collet device  400  with the weight  430  retracted and the vacuum activated, so that the component  440  adheres to the bottom face  412  of the collet  410 . FIG.  5 ( b ) shows the collet device  400  after the vacuum has been deactivated and the weight  430  have fallen to the bottom of the collet  410 . Although the exemplary frame is a tripod, a frame according to the invention may include any desired number of legs, so long as the openings between legs are sufficiently small to retain the weights  430 . 
     Although the weights  230 ,  330 ,  430  are shown as being substantially spherical in the second through fourth embodiments, the weights may be formed in any suitable shape which allows movement of the weights within the respective bores  214 ,  314 ,  414 . Additionally, although the bores  214 ,  314 ,  414  are shown in the second through fourth embodiments as being substantially tubular, the portions may be formed in any suitable shape which allows movement of the weights  230 ,  330 ,  430  therein. 
     Thus, the exemplary embodiments of the present invention provides a vacuum collet device which removes components easily and efficiently. The vacuum collet performs the removal without the need for operator assistance, or complex gas puff equipment. Additionally, the exemplary vacuum collet may be controlled by automated control signals, thereby streamlining the process of producing and transferring components. 
     Although the invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments of the invention which may be made by those skilled in the art without departing from the scope and range of equivalents of the invention.