Abstract:
In a method for attaching a connector to a coaxial cable a solder perform is placed upon an end of an outer conductor of the cable. A connector body of the connector is seated upon an interface pedestal and the end of the outer conductor is inserted into a bore of the connector body against the interface pedestal. The outer conductor, the connector body and the interface pedestal contribute sidewalls to form a solder cavity, and the solder perform is heated. A seat may be applied to the interface pedestal to provide a thermal barrier and/or enhanced seal characteristics that are cost efficiently replaceable upon degradation.

Description:
RELATED APPLICATION 
     This application is a continuation of and claims the benefit of prior U.S. application Ser. No. 13/749,037, filed Jan. 24, 2013, the disclosure of which is hereby incorporated herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a connector and cable interconnection. More specifically, the invention relates to a connector and cable interconnection method and apparatus with improved manufacturing efficiency and electrical performance characteristics. 
     2. Description of Related Art 
     Commonly owned U.S. Pat. No. 5,802,710, titled “Method of Attaching a Connector to a Coaxial Cable and the Resulting Assembly” by Bufanda et al, issued Sep. 8, 1998, hereby incorporated by reference in its entirety, discloses an electrical connector for use with coaxial cable and a method for attaching same. As shown for example in  FIGS. 1 and 2 , the connector may be attached to the coaxial cable with a high level of quality control via an assembly apparatus, as disclosed in commonly owned U.S. Pat. No. 7,900,344, titled “Cable and Connector Assembly Apparatus and Method of Use” by Ng et al, issued Mar. 8, 2011, hereby incorporated by reference in its entirety. 
     The U.S. Pat. No. 5,802,710 connector utilizes an insulating disc retained upon the inner connector and against the cable dielectric and outer conductor. Induction heating of a solder preform wrapped around the outer conductor creates a molten solder pool in a cylindrical solder cavity formed between the outer conductor, the insulating disc and the connector body. The insulating disc prevents the molten solder from migrating out of the cavity, fouling the connector bore and/or shorting the outer and inner conductors. 
     Competition within the cable and connector assembly industry has increased the importance of improving the electro-mechanical characteristics of the cable and connector interconnection while minimizing requirements for proper assembly. 
     Therefore, it is an object of the invention to provide a connector and cable interconnection method and apparatus that overcomes deficiencies in the prior art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention. 
         FIG. 1  shows a schematic isometric view of the primary elements of an exemplary embodiment of a cable assembly apparatus in a ready position, wherein electrical interconnections, supporting and enclosure structures are removed for clarity. 
         FIG. 2  shows a schematic isometric view of the primary elements of an exemplary embodiment of a cable assembly apparatus in an operation position, wherein electrical interconnections, supporting and enclosure structures are removed for clarity. 
         FIG. 3  shows a schematic side view of a prepared end of a coaxial cable. 
         FIG. 4  shows a schematic side view of the coaxial cable of  FIG. 3 , with solder shield and inner contact. 
         FIG. 5  shows a schematic end view of the cable of  FIG. 4 . 
         FIG. 6  shows a schematic side view of the coaxial cable of  FIG. 3 , solder preform and inner contact attached, ready for insertion into a connector body bore for solder interconnection. 
         FIG. 7  shows a schematic cut-away side view of a connector body seated upon an interface pedestal. 
         FIG. 8  shows a schematic cut-away side view of a connector body seated upon an interface pedestal with a bias element. 
         FIG. 9  shows a schematic side view of the connector body and interface pedestal of  FIG. 8  with a coaxial cable inserted into the connector body bore for solder interconnection. 
         FIG. 10  shows a schematic close-up view of the structure of  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION 
     The inventors have recognized that the insulating disc relied upon in the prior connector and assembly apparatus to provide the molten solder containment during interconnection complicates manufacture and introduces an impedance discontinuity that may degrade the electrical performance of the resulting interconnection. 
     The end of a coaxial cable  1  may be prepared for interconnection by stripping back the protective jacket  3  (if present), outer conductor  5 , dielectric  7  and inner conductor  9  to expose desired lengths of each at the cable end, for example as shown in  FIG. 3 . 
     Depending upon the desired interconnection interface and/or coaxial cable  1  configuration, an inner contact  11  may be required to adapt the inner conductor  9  to the desired connection interface inner conductor dimensions. If needed, an inner contact  11  may be soldered upon the prepared end of the inner conductor  9 . To protect the dielectric  7  from thermal damage during soldering, a removable solder shield  13  may be applied between the inner contact  11  and the outer conductor  5  and dielectric  7 , for example as shown in  FIGS. 4 and 5 . 
     A solder preform  15  may be applied proximate the end of the outer conductor  5 , for example, wrapped around the outer conductor  5  as shown in  FIG. 6 . 
     A connector body  17  of the connector may be seated upon the selected interface pedestal  19  of the assembly apparatus  21 , the interface pedestal  19  inserted within a connector body bore  23  of the connector body  17 . As best shown in  FIGS. 7 and 8 , the insertion pedestal  19  may be provided with a shoulder  25  dimensioned to position a solder end of the insertion pedestal  19  at a desired longitudinal position, such as flush with the edge of a solder cavity portion  27  of the connector body bore  23 . 
     A seat  29  may be provided at the solder end of the interface pedestal  19 . The seat  29  formed, for example, of a non-metallic material with insulating characteristics, such as polytetrafluoroethylene, fiberglass reinforced thermoset or polyether ether ketone or the like, provides a thermal break between the connector body  17  and the immediately adjacent portion of the insertion pedestal  19 , so that heat applied to the solder cavity portion  27  is not conducted away by the insertion pedestal  19 , decreasing heat application requirements and thereby the chances for thermal damage to portions of the assembly that may be damaged by excessive heating, such as the dielectric  7 . 
     The seat  29  may also operate as a cost efficient exchangeable wear portion, protecting the interface pedestal  19 . Rather than replace the entire interface pedestal  19 , only the seat  29  need be exchanged when contact surfaces with of the seat  29  become worn. Thereby, the fit between the connector body  17  and the seat  29  may be cost effectively provided with a high dimensional tolerance, reducing the chance that a gap between the seat  29  and the connector body  17  large enough for significant levels of flux and/or molten solder passage may occur. The seat  29  may be removably retained upon the interface pedestal  19 , for example, by a retaining element such as a gasket  31  seated in an annular groove  33  provided in the outer diameter of the interface pedestal  19 . 
     The prepared end of the coaxial cable  1 , with the inner contact  11  and solder preform  15  attached, may be inserted into the cable end of the connector body bore  23 , the connector body  17  already seated upon the interface pedestal  19 , for example as shown in  FIGS. 9 and 10 . Upon insertion, the leading end of the outer conductor  5  seats against the seat  29 , forming a solder cavity  35  between the outer conductor  5 , interface pedestal (seat  29  if present)  19  and connector body  17 . 
     Heat, for example applied via induction heating by a U-shaped inductor  37 , for example as shown in  FIGS. 1 and 2 , or alternatively applied directly to the exterior of the connector body  17 , melts the solder preform  15 , pooling solder within the solder cavity  35 . Where the interface pedestal  19  is oriented with a longitudinal axis that is vertical, gravity retains the molten solder within the solder cavity  35 , even though the solder cavity  35  “top” is open. An inner conductor cavity  39  open to the solder end of the interface pedestal  19  receives the inner conductor  9  with inner contact  11 , if present. 
     Upon cooling, the solder forms an electro-mechanical joint between the outer conductor  5  and the connector body  17 . One skilled in the art will appreciate that the thermal break provided by the seat  29  and/or the thermal mass of the interface pedestal  19  surrounding the inner conductor cavity  39  thermally isolates the solder interconnection between the inner conductor  9  and the inner contact  11 , which may reduce a chance of overheating and/or damage to this solder connection during the outer conductor  5  to connector body  17  solder operation. 
     A flux and/or molten solder seal between the outer conductor  5  and the interface pedestal  19  or seat  29 , if present, may be enhanced by introducing a bias therebetween, for example by providing the interface pedestal  19  or seat  29  with a range of motion along the longitudinal axis biased by a bias element, such as a spring  40 , for example as shown in  FIG. 8 . Alternatively, a grip clamp  41 , for example as shown in  FIGS. 1 and 2 , may be biased toward the interface pedestal  19  when the grip clamp  41  is engaged to grip the cable, thereby biasing the outer conductor  5  against the interface pedestal  19  or seat  29 , if present. 
     For ease of use with a range of different connector interface types, the interface pedestal  19  may be configured for ease of exchange via, for example, a fastener inserted into a retention hole  43  at an assembly apparatus end of the interface pedestal  19 . 
     One skilled in the art will appreciate that the general interconnection process does not have a specific order of operation with respect to the connector body  17  and the interface pedestal  19 . For example, instead of seating the connector body  17  upon the interface pedestal  19  and then inserting the outer conductor  5  and solder preform  15  into the connector body bore  23 , the outer conductor  5  and solder preform  15  may be initially inserted into the connector body bore  23  and this assembly then seated upon the interface pedestal  19 . 
     Because the connector and cable assembly apparatus together eliminate the need for application of an additional insulating disc to each connector, the total number of connector components and the number of required assembly operations has been reduced, which may increase manufacture efficiency. Further, the elimination of the insulating disc removes an impedance discontinuity, which may improve the electrical performance of the interconnection. 
     The presence of the seat  29  enables tighter tolerances and may significantly extend the useful operating life of the insertion pedestal  19 . Finally, the presence of the seat  29  improves thermal isolation, which may reduce the total heat and thus time required to perform the outer conductor solder operation as well as reduce the chances for thermal damage to the dielectric  7  and/or the previously applied inner conductor  9  to inner contact  11  solder connection, if present. 
     
       
         
               
             
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Table of Parts 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 coaxial cable 
               
               
                 3 
                 jacket 
               
               
                 5 
                 outer conductor 
               
               
                 7 
                 dielectric 
               
               
                 9 
                 inner conductor 
               
               
                 11 
                 inner contact 
               
               
                 13 
                 solder shield 
               
               
                 15 
                 solder perform 
               
               
                 17 
                 connector body 
               
               
                 19 
                 interface pedestal 
               
               
                 21 
                 assembly apparatus 
               
               
                 23 
                 connector body bore 
               
               
                 25 
                 shoulder 
               
               
                 27 
                 solder cavity portion 
               
               
                 29 
                 seat 
               
               
                 31 
                 gasket 
               
               
                 33 
                 annular groove 
               
               
                 35 
                 solder cavity 
               
               
                 37 
                 inductor 
               
               
                 39 
                 inner conductor cavity 
               
               
                 40 
                 spring 
               
               
                 41 
                 grip clamp 
               
               
                 43 
                 retention hole 
               
               
                   
               
             
          
         
       
     
     Where in the foregoing description reference has been made to ratios, integers or components having known equivalents then such equivalents are herein incorporated as if individually set forth. 
     While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus, methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of applicant&#39;s general inventive concept. Further, it is to be appreciated that improvements and/or modifications may be made thereto without departing from the scope or spirit of the present invention as defined by the following claims.