Abstract:
A self-fixturing, self-aligning coaxial connector assembly is provided. The coaxial connector assembly comprises a coaxial connector, a coaxial housing and a printed circuit board. The printed circuit board is aligned properly with the electrical end of the coaxial connector when mounted on the coaxial housing and is held in place while the printed circuit board is coupled to the coaxial housing.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to coaxial connector assemblies for use in securing an end launch coaxial connector to an electronic device such as a printed circuit board. More specifically, the present invention comprises a coaxial housing securable to, for example, an end launch coaxial connector through one or more self-aligning, self-fixturing mounting terminals for attachment to a device such as a printed circuit board. 
       BACKGROUND OF THE INVENTION 
       [0002]    There are a variety of known ways to secure a coaxial connector to an electrically conductive substrate such as a printed circuit board (PCB). One common way is soldering or bonding the two together. Proper alignment of the coaxial connector and the PCB is essential for optimal operation, and it is often difficult to align the coaxial connector properly with a signal trace on the PCB while bonding the coaxial connector. A series of connective and other problems can occur if there is misalignment or if the coaxial connector is not secured effectively. 
         [0003]      FIG. 4  illustrates the electric field patterns of a coaxial device cross section.  FIG. 5  illustrates a coplanar circuit with “ground under.”  FIG. 6  illustrates the same coplanar circuit with a contact applied to the signal trace of the PCB for the purpose of launching the signal between the planar and coaxial devices. It is critical that the coaxial connector center contact be coplanar or nearly coplanar to the signal trace on the PCB for efficient signal transfer. Any disposition of the contact away from the PCB surface causes additional fringe capacitive effects and makes bonding more difficult to achieve. Excessive capacitance causes impedance error and signal loss in radio frequency (RF) circuitry. 
         [0004]    There are several known approaches to keep the coaxial connector aligned and stationary for attachment to a PCB. For example, U.S. Pat. No. 5,404,117 discloses an electronic connector for connecting a coaxial cable to a microstrip transmission line or to a coplanar transmission line. To ensure proper alignment of the PCB and coaxial cable the optimal connection is detected with an electronic device before attachment, requiring time and adjustment. 
         [0005]    Referring to  FIG. 1 , in this approach an end launch coaxial connector  14  has cooperating straight and parallel terminals  15   a ,  15   b  manufactured with a fixed separation gap  16  to receive a PCB. The gap  16  created between the signal side terminals and the ground side terminals is of a width equal to the thickness of the PCB thickness plus the appropriate tolerance buildup (typically 0.006″).  FIG. 2  illustrates PCB  17  misaligned with center connector  18 . If PCB  17  is soldered in the configuration illustrated in  FIG. 2 , the connection between center contact  18  and PCB  17  will be poor. 
         [0006]      FIG. 3  illustrates a fixture  19  that can be used to hold in place the center contact  18  and the PCB  17 . Fixture  19  is used to secure the coaxial connector  14  and PCB  17  during the bonding process to maintain coplanarity of center contact  18  to the PC trace. Fixture  19  is also needed to keep the axis of center contact  18  parallel to the PCB plane for proper alignment to mating connectors, electronic housing enclosure ports, and associated packaging hardware. Coaxial connector  14  and PCB  17  each have to be placed on fixture  19  and be properly aligned. If fixture  19  is moved or bumped before bonding occurs it can lead to misalignment of the center contact  18  and the PC trace on PCB  17 . 
         [0007]    It is essential and some times difficult to ensure proper alignment between the center contact and the PC trace on the PCB efficiently and on a consistent basis. Therefore, it would be beneficial to provide a coaxial housing that has the ability to align the center contact and PCB easily and hold in place until soldering or other bonding can occur. It would also be beneficial if the coaxial housing is manufactured at that same time as the coaxial connector and is part of the coaxial connector. 
         [0008]    Besides misalignment, excessive soldering can create a poor signal so it is important to be precise when bonding the coaxial connector. Therefore, it would be beneficial to provide a system for fixing the PCB and the coaxial connector that does not involve the user doing anything else but applying the bonding material. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention relates to a self-fixturing, self-aligning coaxial connector assembly. A principal object of the present invention is to provide a coaxial housing for an end launch coaxial connector that has a self alignment feature and a self fixturing feature in order to provide the proper alignment of the coaxial connector with the PCB and a self supportive structure in order to keep the PCB in place until the coaxial connector is coupled to the PCB. The coaxial housing can provide alignment and fixture of a PCB that is assembled to a fixed end launch coaxial connector or multiple coax feed thru block until the PCB is bonded to the coaxial housings. The present invention comprises a coaxial connector having a center contact protruding from a signal end of the coaxial connector along the center axis of the coaxial connector and a coaxial housing having an opening in the approximate center of the coaxial housing where the coaxial contact protrudes through the opening. The coaxial housing has at least one arm protruding from the face of the coaxial housing and at least one leg protruding from the face of the coaxial housing at the base of the coaxial housing. The legs protrude at a slight upward angle from the base of coaxial connector. The arms are generally coplanar to the center contact. The legs are offset from the plane of the center contact and generally parallel with the arms. A gap is created between the arms and the legs that is approximately the width of the PCB. The PCB is placed in the gap between the arms and legs which automatically aligns the PCB properly with the center contact. The arms and legs are also self-fixturing so that the PCB will be held in place while a bonding agent is applied to bond the center contact with the PCB. The assembly provides proper mounting, alignment and securement of the PCB while the PCB and the coaxial connector are bonded. 
         [0010]    The foregoing and other objects are intended to be illustrative of the invention and are not meant in a limiting sense. Many possible embodiments of the invention may be made and will be readily evident upon a study of the following specification and accompanying drawings comprising a part thereof. Various features and subcombinations of invention may be employed without reference to other features and subcombinations. Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, an embodiment of this invention and various features thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    A preferred embodiment of the invention, illustrative of the best mode in which the applicant has contemplated applying the principles, is set forth in the following description and is shown in the drawings and is particularly and distinctly pointed out and set forth in the appended claims. 
           [0012]      FIG. 1  (prior art) is a sectional view of a known end launch coaxial connector. 
           [0013]      FIG. 2  (prior art) illustrates the connector of  FIG. 1  with a misaligned PCB. 
           [0014]      FIG. 3  (prior art) illustrates the connector of  FIG. 1  with a fixture device used to stabilize the PCB during soldering. 
           [0015]      FIG. 4  is a schematic illustration of the electric field of a coaxial transmission line. 
           [0016]      FIG. 5  is a schematic illustration of the electric field of a coplanar circuit which is ground under. 
           [0017]      FIG. 6  is a schematic illustration of the electric field of a coplanar circuit with a center contact soldered to the signal trace on the PCB. 
           [0018]      FIG. 7  is a perspective view of a coaxial connector assembly illustrating an exemplary embodiment of the present invention. 
           [0019]      FIG. 8  is a sectional view of the coaxial connector assembly of  FIG. 7  showing a PCB partially inserted into a coaxial housing of the coaxial connector. 
           [0020]      FIG. 9  is a sectional view of the coaxial connector assembly showing the PCB fully inserted into the coaxial housing. 
           [0021]      FIG. 10  is a perspective view of the coaxial connector assembly showing the coaxial housing coupled to the PCB. 
           [0022]      FIG. 11  is a front view of a coaxial connector coupled with a coaxial housing coupled to a PCB. 
           [0023]      FIG. 12  is a perspective view of a modified embodiment of the present invention showing a multi-port coaxial feed with multiple coaxial housings and multiple PCBs coupled to coaxial housings. 
           [0024]      FIG. 13  is a partial sectional view of the embodiment depicted in  FIG. 12 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]    As required, one or more detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the principles of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. 
         [0026]    A preferred embodiment of a coaxial connector assembly  100  of the present invention, illustrated in  FIGS. 7-9 , comprises a coaxial connector  1 , an electrically conductive substrate such as PCB  2 , and a coaxial housing  3 . PCB  2  is a conventional printed circuit board or other electronic planer device with at least a signal side  7  and a ground side  10  opposing signal side  7 . The coaxial connector  1  has at least one electronic contact  5  protruding from a circuit end  4  of coaxial connector  1 . Coaxial housing  3  has a main body  30  with a front  31 , a rear  32 , and an opening  33  between the front  31  and the rear  32 . In the preferred embodiment illustrated in  FIG. 7 , coaxial housing  3  has a pair of arms  6   a ,  6   b  protruding from front  31 . Top surfaces of arms  6   a ,  6   b  are generally coplanar to a center line  34  of the opening  33 . In a preferred embodiment, the ends of arms  6   a ,  6   b  are rounded or sloped on the front bottom edge farthest from front  31 . Coaxial housing  3  has a pair of legs  8   a ,  8   b  protruding from front  31  at a base  40  of front  31 . Legs  8   a ,  8   b  are positioned on a plane offset from the coincident plane of center contact  5  and arms  6   a ,  6   b  by a distance equal to PCB  2  thickness plus appropriate tolerance buildup of approximately 10%. A gap  41  is created for PCB  2 . Legs  8   a ,  8   b  extend from base  40  at an angle  11  measuring approximately less than or equal to 10 degrees. In a preferred embodiment, illustrated in  FIG. 8 , angle  11  is 6 degrees and include sloped outer tips. In a preferred embodiment coaxial housing  3  and coaxial connector  1  are manufactured of the same material, at the same time and as one unit. 
         [0027]    Referring to  FIG. 7 , the coaxial connector  1  is mounted to the coaxial housing  3 . Center contact  5  protrudes through opening  33  such that center contact  5  and arms  6   a ,  6   b  are generally coplanar. Arms  6   a ,  6   b  and center contact  5  provide termination to signal side  7  of PCB  2 . Legs  8   a ,  8   b  provide termination to PCB  2  ground side  10 . PCB  2  can be mounted in gap  41  between arms  6   a ,  6   b  and legs  8   a ,  8   b  in alignment with center contact  5 . Angle  11  reduces the gap width provided for PCB  2 . 
         [0028]    Referring to  FIG. 8 , when coaxial connector  1  is pushed onto the edge of a fixed PCB  2  legs  8   a  and  8   b , provide a continuous spring force that acts upon ground side  10  of PCB  2  and in a direction normal to PCB  2  circuit planes. Center contact  5  is forced against signal side  7  of PCB  2 . The reactant force between arms  6   a ,  6   b  and the surface of PCB  2  causes the center contact  5  to align nearly parallel to signal side  7  of PCB  2 . Legs  8   a ,  8   b  create a normal force on ground side  10  of PCB  2 . The normal force creates an equal and opposite force on signal side  7  against the center contact  5  and arms  6   a ,  6   b . This is a gripping force to hold coaxial connector  1  and center contact  5  in position on PCB  2  until a bonding agent is applied to the arms and legs and PCB joints. This coaxial housing design eliminates the need for additional fixture support during the bonding of coaxial connector  1  and PCB  2 .  FIGS. 10 and 11  illustrate coaxial connector assembly  100 , with center contact  5  of coaxial connector  1  properly aligned with PCB  2 . 
         [0029]    Coaxial connector  1  and coaxial housing  3  may be fixed and PCB  2  is slid into gap  41 , or PCB  2  may be fixed and coaxial connector  1  and coaxial housing  3  can be pushed onto PCB  2 . Either way the spring force caused by legs  8   a ,  8   b  provide alignment and gripping forces to push and hold PCB  2  parallel and against the coaxial center contact plane until bonding agent is applied to the appropriate places. 
         [0030]    In one embodiment, the ends of arms  6   a ,  6   b  and legs  8   a ,  8   b  and center contact  5  have chamfer or radius ends to improve assembly to the PCB without excessive insertion forces or excessive scraping of PCB materials. 
         [0031]    Referring to  FIG. 9 , in a preferred embodiment, coaxial housing  3  has a thickened boss  12  at base  40  of one or more legs  8   a ,  8   b  to increase the shear strength of legs  8   a ,  8   b  and coaxial housing  3 . This provides the necessary strength to survive the shear moments that occur in the coaxial housings when a mating connector is coupled at a mating end  13  of coaxial connector  1  and torqued to specified operating values. 
         [0032]    In a modified embodiment of the present invention, illustrated in  FIGS. 12 and 13 , a multi-port coaxial connector assembly  200  comprises at least one coaxial connector  202  enclosed within a housing  204 . An electrically conductive tip  206  protrudes generally outward from a front face of the housing  204 . A plurality of pairs of arms  208 ,  210  and legs  212 ,  214  are formed along the front surface of the housing  204 . The arms  208 ,  210  and legs  212 ,  214  are configured in a manner similar to that described above for receiving and mounting one or more PCB  216 . 
         [0033]    In the foregoing description, certain terms have been used for brevity, clearness and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, the description and illustration of the inventions is by way of example, and the scope of the inventions is not limited to the exact details shown or described. 
         [0034]    Although the foregoing detailed description of the present invention has been described by reference to an exemplary embodiment, and the best mode contemplated for carrying out the present invention has been shown and described, it will be understood that certain changes, modification or variations may be made in embodying the above invention, and in the construction thereof, other than those specifically set forth herein, may be achieved by those skilled in the art without departing from the spirit and scope of the invention, and that such changes, modification or variations are to be considered as being within the overall scope of the present invention. Therefore, it is contemplated to cover the present invention and any and all changes, modifications, variations, or equivalents that fall with in the true spirit and scope of the underlying principles disclosed and claimed herein. Consequently, the scope of the present invention is intended to be limited only by the attached claims, all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
         [0035]    Having now described the features, discoveries and principles of the invention, the manner in which the invention is constructed and used, the characteristics of the construction, and advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangements, parts and combinations, are set forth in the appended claims. 
         [0036]    It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.