Abstract:
A printed circuit board conveying and processing system. In accordance with the present invention, a printed circuit board conveying system is provided comprising a pair of conveyor rails and a printed circuit board support. The conveyor rails are positioned to engage opposite lateral edge portions of a printed circuit board along a conveyor path. The printed circuit board support is positioned to support a major portion of the printed circuit board between the lateral edge portions. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR §1.72(b).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a division of co-pending application Ser. No. 09/704,294, filed Nov. 1, 2000 entitled “PRINTED CIRCUIT BOARD SUPPORT”, and is further related to co-pending application Ser. Nos. ______ (Attorney Docket No. MIO 0070 V2), ______, (Attorney Docket No. MIO 0070 V3), and ______ (Attorney Docket No. MIO 0070 V4), which are all entitled “PRINTED CIRCUIT BOARD SUPPORT”. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to printed circuit board handling and manufacturing processes and, more particularly, to an improved printed circuit board support, printed circuit board conveying system, and printed circuit board processing system.  
           [0003]    Conventional printed circuit board processing systems, e.g., SMT (surface mount technology) manufacturing systems, typically utilize a conveyor system to move a printed circuit board from station to station within the system. Often, the printed circuit board is supported or held in a manner that is insufficient to prevent the board from warping, twisting, or bending during processing. Accordingly, there is a need in the art of printed circuit board handling and processing for an improved printed circuit board support.  
         BRIEF SUMMARY OF THE INVENTION  
         [0004]    This need is met by the present invention wherein an improved printed circuit board support, an improved printed circuit board conveying system, and an improved printed circuit board processing system are provided. In accordance with one embodiment of the present invention, a printed circuit board support is provided comprising a support base, a spacer, and a spacer securement. The support base defines a support surface. The spacer engages the support surface. The spacer securement includes a projection and a recess. The projection adjoins one of the support base and the spacer. The recess is formed in the other of the support base and the spacer. The projection extends into the recess and the projection and the recess are configured such that the extension of the projection into the recess limits movement of the spacer relative to a plane parallel to the support surface.  
           [0005]    The printed circuit board support may comprise two or more spacer securements. The projection may comprise a substantially cylindrical pin and the recess may comprise a cylindrical recess having a diameter slightly larger than the pin. The spacer may define an upper spacer surface spaced from and substantially parallel to the support surface.  
           [0006]    In accordance with another embodiment of the present invention, a printed circuit board support assembly is provided comprising a support base and a plurality of spacers. The support base defines a support surface and at least one recess formed therein. The recess defines an opening on the support surface. The plurality of spacers define respective upper spacer surfaces and opposite spacer surfaces. The spacers define a range of respective thickness dimensions between respective ones of the spacer surfaces and corresponding ones of the opposite spacer surfaces. Each of the spacers includes at least one projection extending from the opposite spacer surface. The respective projections and the recess formed in the support base are sized to enable extension of the respective projections into the recess and to limit movement of the spacer relative to a plane parallel to the support surface.  
           [0007]    In accordance with yet another embodiment of the present invention, a printed circuit board support is provided comprising a support base. The support base defines a support surface, a leading edge, a trailing edge, and a pair of lateral edges. The support base also defines a cut-out formed therein. The cut-out is positioned between the pair of lateral edges and extends from the leading edge in the direction of the trailing edge to a position between the leading edge and the trailing edge.  
           [0008]    The leading edge, the trailing edge, and the pair of lateral edges may be defined in a substantially planar surface of the support base. The cut-out may be formed in the support surface of the support base. The printed circuit board support may further comprise a spacer and a spacer securement. The spacer engaging the support surface and including an additional cut out formed therein and the spacer securement arranged to secure the spacer to the support surface with the additional cut-out aligned with the cut-out formed in the support base. The additional cut-out and the cut-out in the support base may be coextensive. The additional cut out may be formed in an upper spacer surface of the spacer.  
           [0009]    In accordance with yet another embodiment of the present invention, a printed circuit board support is provided comprising a support base defining a support surface. A base extension assembly is secured to the support base and is arranged to define a variable extension assembly height dimension and at least a portion of a height dimension of the printed circuit board support, wherein variation of the variable extension assembly height dimension results in variation of the height dimension of the printed circuit board support.  
           [0010]    The base extension assembly may be further arranged such that the extension assembly height dimension varies in response to a force applied to the support surface. The base extension assembly comprises a spring-loaded extension including a spring arranged to compress in response to a force applied to the support surface. The base extension assembly may comprise a viscously damped extension arranged to compress in response to a force applied to the support surface. The base extension assembly may comprise a pair of support legs. Each of the pair of support legs may be arranged such that the extension assembly height dimension varies in response to a force applied to the support surface.  
           [0011]    In accordance with yet another embodiment of the present invention, a printed circuit board support is provided comprising a support base, a base extension, and a magnetic source. The support base defines a support surface and a lower surface. The base extension is secured to the support base and is arranged to define at least a portion of a height dimension of the printed circuit board support. A magnetic source is secured to the base extension and is positioned such that the lower surface of the support base is arranged to secure the printed circuit board support to an object under magnetic force. The magnetic source may comprise a permanent magnet and may be secured within a cavity formed in the lower surface of the support base.  
           [0012]    In accordance with yet another embodiment of the present invention, a printed circuit board conveying system is provided comprising a pair of conveyor rails and a printed circuit board support. The pair of conveyor rails are positioned to engage opposite lateral edge portions of a printed circuit board and are configured to convey the printed circuit board along a conveyor path. The printed circuit board support is positioned to support a portion of the printed circuit board between the lateral edge portions. The printed circuit board support comprises a support base defining a support surface, a spacer engaging the support surface, and a spacer securement including a projection and a recess. The projection adjoins one of the support base and the spacer. The recess is formed in the other of the support base and the spacer. The projection extends into the recess. The projection and the recess are configured such that the extension of the projection into the recess limits movement of the spacer relative to a plane parallel to the support surface. A thickness dimension of the spacer is selected to enable engagement of the spacer with the printed circuit board.  
           [0013]    In accordance with yet another embodiment of the present invention, a printed circuit board conveying system is provided comprising a pair of conveyor rails, a printed circuit board support, and a stop mechanism. The pair of conveyor rails are positioned to engage opposite lateral edge portions of a printed circuit board and are configured to convey the printed circuit board along a conveyor path. The printed circuit board support is positioned to support a portion of the printed circuit board between the lateral edge portions and comprises a support base. The support base defines a support surface, a leading edge, a trailing edge, a pair of lateral edges, and a cut-out formed therein. The cut-out is positioned between the pair of lateral edges and extends from the leading edge in the direction of the trailing edge to a position between the leading edge and the trailing edge. The stop mechanism is positioned to engage the printed circuit board support at a point within the cut-out. The stop mechanism may include an actuator and a pin and may be configured to selectively extend and retract the pin to and from a position engaging the printed circuit board support at the point within the cut-out.  
           [0014]    In accordance with yet another embodiment of the present invention, a printed circuit board conveying system is provided comprising a pair of conveyor rails and a printed circuit board support. The pair of conveyor rails are positioned to engage opposite lateral edge portions of a printed circuit board and configured to convey the printed circuit board along a conveyor path. The printed circuit board support is positioned to support a portion of the printed circuit board between the lateral edge portions and comprises a support base and a base extension assembly. The support base defines a support surface. The base extension assembly is secured to the support base and is arranged to define a variable extension assembly height dimension and at least a portion of a height dimension of the printed circuit board support. Variation of the variable extension assembly height dimension results in variation of the height dimension of the printed circuit board support. The base extension assembly is configured such that the height dimension of the printed circuit board support permits engagement of the support surface with the printed circuit board.  
           [0015]    In accordance with yet another embodiment of the present invention, a printed circuit board conveying system is provided comprising a pair of conveyor rails, a conveyor platform, and a printed circuit board support. The pair of conveyor rails are positioned to engage opposite lateral edge portions of a printed circuit board and are configured to convey the printed circuit board along a conveyor path. The printed circuit board support is positioned to support a portion of the printed circuit board between the lateral edge portions. The printed circuit board support comprises a magnetic source secured to the base extension assembly and positioned such that the lower surface of the support base secures the printed circuit board support to the conveyor platform under magnetic force, wherein the base extension assembly is configured such that the height dimension of the printed circuit board support permits engagement of the support surface with the printed circuit board.  
           [0016]    In accordance with yet another embodiment of the present invention, a printed circuit board processing system is provided. The system includes a printed circuit board conveying system coupling a printed circuit board loader to a stencil printer, a pick and place machine, and a reflow oven. The printed circuit board conveying system comprises a pair of conveyor rails and a printed circuit board support according to the present invention.  
           [0017]    In accordance with yet another embodiment of the present invention, a method of conveying a printed circuit board in a printed circuit board conveying system is provided. The conveying system is provided in accordance with the present invention and the conveying method comprises the steps of selecting one of the plurality of spacers as a function of its thickness and a thickness profile of the printed circuit board engaged by the pair of conveyor rails; installing the selected spacer by extending at least one of the respective projections into the recess; and engaging an upper spacer surface of the selected spacer with the printed circuit board.  
           [0018]    In accordance with yet another embodiment of the present invention, a method of conveying a printed circuit board in a printed circuit board conveying system is provided. The conveying system is provided in accordance with the present invention and the conveying method comprises the steps of engaging the support surface of the support base with the printed circuit board engaged by the pair of conveyor rails and varying the height dimension of the base extension assembly as a function of a thickness profile of the printed circuit board.  
           [0019]    In accordance with yet another embodiment of the present invention, a method of processing a printed circuit board in a processing system including a printed circuit board conveying system coupling a printed circuit board loader to a stencil printer, a pick and place machine, and a reflow oven is provided. The printed circuit board conveying system is provided in accordance with the present invention and the processing method comprises the steps of selecting one of the plurality of spacers as a function of its thickness and a thickness profile of the printed circuit board engaged by the pair of conveyor rails, installing the selected spacer by extending at least one of the respective projections into the recess, and engaging an upper spacer surface of the selected spacer with the printed circuit board within the operating envelope of the pick and place machine.  
           [0020]    In accordance with yet another embodiment of the present invention, a method of processing a printed circuit board in a processing system including a printed circuit board conveying system coupling a printed circuit board loader to a stencil printer, a pick and place machine, and a reflow oven is provided. The printed circuit board conveying system is provided in accordance with the present invention and the processing method comprises the steps of engaging the support surface of the support base with the printed circuit board engaged by the pair of conveyor rails within the operating envelope of the pick and place machine and varying the height dimension of the base extension assembly as a function of a thickness profile of the printed circuit board.  
           [0021]    Accordingly, it is an object of the present invention to provide an improved printed circuit board support, an improved printed circuit board conveying system, and an improved printed circuit board processing system. Other objects of the present invention will be apparent in light of the description of the invention embodied herein. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0022]    The following detailed description of the preferred embodiments of the present invention can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:  
         [0023]    [0023]FIG. 1 is an illustration of a printed circuit board support according to/one embodiment of the present invention;  
         [0024]    [0024]FIG. 2 is an illustration of a printed circuit board support according to another embodiment of the present invention;  
         [0025]    [0025]FIG. 3 is an illustration of a printed circuit board support according to yet another embodiment of the present invention;  
         [0026]    [0026]FIG. 4 is an illustration of a printed circuit board conveying system according to the present invention; and  
         [0027]    [0027]FIG. 5 is an illustration of a printed circuit board processing system. 
     
    
     DETAILED DESCRIPTION  
       [0028]    Referring now to FIGS.  1 - 5  a printed circuit board support  5 , printed circuit board conveying system  60 , and a printed circuit board processing system  70  according to the present invention are illustrated. The printed circuit board support  5  illustrated in FIG. 1 comprises a support base  10  defining a support surface  12 . A base extension assembly  20  is secured to the support base  10 . The base extension assembly  20  may be secured to the support base  10  by forming the extension assembly  20  and the support base  10  as a single integral piece or by coupling two separate pieces mechanically, adhesively, magnetically, or otherwise.  
         [0029]    The support base  10  defines a leading edge  14 , a trailing edge  16 , and a pair of lateral edges  18 . As is illustrated in FIG. 1, the leading edge  14 , the trailing edge  16 , and the pair of lateral edges  18  are defined in a substantially planar support surface  12  of the support base  10 . In the illustrated embodiment, the base extension assembly  20  comprises a pair of support legs  22 ,  24 .  
         [0030]    According to one embodiment of the present invention, a cut-out  15  is formed in the support base  10 . The cut-out  15  is positioned between the pair of lateral edges  18  and extends from the leading edge  14  in the direction of the trailing edge  16  to a position between the leading edge  14  and the trailing edge  16 . In the illustrated embodiment, the cut-out  15  is formed in the support surface  12  of the support base  10 . The purpose of the cut-out  15  is illustrated in further detail herein with reference to the function of the conveying and processing systems of the present invention.  
         [0031]    Referring specifically to FIGS. 1 and 2, the printed circuit board support  5  may further comprise a pair of permanent magnets  30  secured within respective cavities in each of the support legs  22 ,  24  of the base extension  20 . The magnets  30  are positioned such that the lower surface of the support base  10  is arranged to secure the printed circuit board support  5  to a conveyor platform or other object  40  under magnetic force. Alternative magnetic sources  30 , e.g., electromagnets, may be provided without departing from the scope of the present invention.  
         [0032]    The base extension assembly  20  may comprise a single molded piece with or without attachments or, as is illustrated in FIG. 3, may comprise a compound assembly arranged to define a variable height dimension a of the extension assembly  20  and at least a portion of a height dimension b of the printed circuit board support  5 . As will be appreciated by those practicing the present invention, variation of the variable extension assembly height dimension a results in variation of the height dimension b of the printed circuit board support  5 .  
         [0033]    The extension assembly  20  illustrated in FIG. 3 may comprise a spring arranged to compress in response to a force applied to the support surface  12 , a viscously damped extension arranged to compress in response to a force applied to the support surface  12 , or any other components arranged to enable variation of the height dimension a of the extension assembly  20 . The variation of the height dimension a may be in response to a force applied to the support surface  12  or may be a result of selective control of the height dimension a independent of the force applied to the support surface  12 . In the illustrated embodiment, each of the pair of support legs  22 ,  24  are arranged, in the manner described herein, such that the extension assembly height dimension is variable.  
         [0034]    Referring further to FIG. 2, an additional embodiment of the present invention is illustrated. A spacer  50  is provided in engagement with the support surface  12 . A spacer securement  52  includes a recess  54  in the form of a cylindrical bore and a projection  56  in the form of a pin. In the illustrated embodiment, the pin  56  is mounted to or formed integrally with the spacer  50  and the recess  54  is formed in the support base  10 . It is contemplated, however, that the pin  56  may be mounted to the support base  10  and the recess  54  may be formed in the spacer  50 .  
         [0035]    In the engaged state, the projection  56  extends into the recess  54  and the projection  56  and the recess  54  are configured such that the extension of the projection  56  into the recess  54  limits movement of the spacer  50  relative to a plane parallel to the support surface  12 . As is illustrated in FIG. 2, the printed circuit board support  5  may comprise at least two spacer securements  52 .  
         [0036]    The spacer  50  functions to provide an upper spacer surface  58  spaced from and substantially parallel to the support surface  12 . As clearly illustrated in FIGS. 2 and 4, the upper spacer surface  58  is sized and configured to support and engage a major portion of a printed circuit board  80 . Most preferably a plurality of spacers of different thicknesses are made available for engagement with the support base  10 . In this manner, the printed circuit board support  5  may be configured to support a variety of printed circuit boards of varying thickness profiles.  
         [0037]    In the embodiment illustrated in FIG. 2, the spacer  50  engaging the support surface  12  includes an additional cut out  55  formed therein. The spacer securements  52  are arranged to secure the spacer  50  to the support surface  12  with the additional cut-out  55  aligned with the cut-out  15  formed in the support base  10 . Typically, the additional cut-out  55  and the cut-out  15  in the support base  10  are coextensive, i.e., they have substantially the same spatial scope or boundaries. Moreover, as clearly illustrated in FIGS.  1 - 3 , the cut-out  15  transects the thickness of the support base  10  and, as clearly illustrated in FIG. 2, the additional cut-out  55  transects the thickness of the spacer  50 . The additional cut out  55  is formed in an upper spacer surface  58  of the spacer  50 . The upper surface  58  of the spacer  50  and the support surface  12  collectively define a pair of supportive extensions  25  which provide additional support for printed circuit boards that extend across the cut-out  15  and the additional cut-out  55 .  
         [0038]    Referring now to FIGS. 4 and 5, a printed circuit board conveying system, a printed circuit board processing system, and their manners of operation are described. A printed circuit board conveying system  60  is incorporated within the processing system  70  and includes a conveyor  62  coupling a printed circuit board loader  72  to a stencil printer  74 , a pick and place machine  76 , and a reflow oven  78 . The printed circuit board conveying system  60  comprises a pair of conveyor rails  64  positioned to engage opposite lateral edge portions  82  of a printed circuit board  80  and is configured to convey the printed circuit board  80  along a conveyor path, as indicated by directional arrow  66 . A printed circuit board support  5  according to the present invention is positioned to support a major portion of the printed circuit board  80  between the lateral edge portions  82  within an operating envelope of the pick and place machine  76 . It is contemplated by the present invention that the printed circuit board support  5  may be positioned to support a major portion of the printed circuit board  80  within the respective operating envelopes of other components of the processing system  70  as well.  
         [0039]    A stop mechanism  90  is illustrated in FIG. 4, and includes an actuator  92  and a pin  94 . The stop mechanism  90  is configured to selectively extend and retract the pin  94  to and from a position engaging the printed circuit board support  5  at a point within the cut-out  15 . In this manner, the stop mechanism  90  may be utilized to control the movement of selected printed circuit board supports  5  along the conveyor path.  
         [0040]    In operation, one of a plurality of spacers  50  (See FIG. 2) having different thicknesses is selected depending upon the thickness profile of the printed circuit board  80  engaged by the pair of conveyor rails  64 . More specifically, the spacer  50  having a thickness most suitable for optimum supportive engagement of the printed circuit board  80  by the printed circuit board support  5  is selected. The selected spacer  50  is installed by extending or positioning the respective projections  56  into the corresponding recesses  54 . The upper spacer surface  58  of the selected spacer  50  is then utilized to engage the printed circuit board  80  within the operating envelope of the pick and place machine  76 . Alternatively, the spacer  50  may be eliminated and the base extension assembly  20  may be arranged to define a variable extension assembly height dimension a, as discussed herein with reference to FIG. 3, and the height dimension of the base extension assembly  20  may be varied as a function of a thickness profile of the printed circuit board  80 . In which case the upper surface  12  will engage the printed circuit board  80 . It is contemplated that the variable height base extension assembly  20  and the spacers  50  may be utilized in a cooperative relationship in a single embodiment of the present invention.  
         [0041]    Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims. More specifically, although some aspects of the present invention are identified herein as preferred or particularly advantageous, it is contemplated that the present invention is not necessarily limited to these preferred aspects of the invention.