Patent Publication Number: US-6671174-B1

Title: 5-pin surface mount contacts and block assembly

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to surge protection devices for protecting telecommunications related equipment from power and transient surges. More particularly, it relates to a surge protector block assembly formed of a plurality of individual 5-pin housing units each housing unit having surface mountable contacts for connecting electrically to conductive traces on a single and/or multi-layer printed circuit board via solder pads. 
     As is generally well-known to those skilled in the telecommunications industry, modern telecommunications equipment is susceptible to transient surges such as those caused by lightning strikes and other surges on the transmission lines. Thus, various arrangements of surge protector circuits are known in the prior art which have been provided for connecting to each pair of incoming telephone lines so as to be normally non-conductive but are rendered conductive when a high voltage surge exceeds a predetermined breakdown voltage (e.g., 250 V) for protecting the equipment. Each pair of incoming telephone lines includes a “tip” line and a “ring” line. Each of the tip and ring lines is typically connected to a conventional 5-pin surge protector module via a protector block. One of the five pins is connected to an incoming tip line. A second one of the five pins is connected to an incoming ring line. A third one of the five pins is connected to an outgoing tip line. A fourth one of the five pins is connected to an outgoing ring line. A fifth one is connected to a ground potential. 
     The traditional method for connecting a cable having a plurality of incoming tip and ring telephone lines to the protector block has been to manually wire-wrap each line to the proper pin on the protector block. In view of the large number of telephone lines coming into a building or plant, the wire-wrapping of each line is a very time-consuming process. There is known heretofore in the prior art a method for eliminating wire-wrapping for the protector block assemblies. This prior art method utilized a multi-layer printed circuit board having a plurality of sockets formed by through-holes that are plated with metal. A protector module is provided with a plurality of pins that are inserted into the corresponding sockets formed in the multi-layer printed circuit board. 
     However, this prior art technique suffers from a number of disadvantages. Firstly, the use of the plurality of sockets or plated through-holes in the multi-layer printed circuit board increases not only the space requirements (i.e., real estate) but also increases the labor and manufacturing costs involved in fabricating the plurality of sockets. Secondly, the use of the plurality of sockets in the multi-layer printed circuit board prevents the placement or routing of the conductive traces on the various layers thereof across the areas of where the sockets are located, thereby adversely affecting optimal utilization of the multi-layers. Thirdly, the through-holes being plated with metal cause high inductance at high frequencies which may affect negatively the operation of the electrical circuits. 
     In view of these problems, the inventors have developed a way of eliminating the need for wire-wrapping of the protector block assemblies but yet solves all of the problems encountered in the prior art method. This is achieved by the provision of a single and/or multi-layer printed circuit board having a plurality of solder pads for electrical connection to corresponding ones of a plurality of surface mountable socket contacts disposed within a surge protector block assembly. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a general object of the present invention to provide an improved surge protector block assembly which is relatively simple and economical to manufacture and assemble but yet overcomes all of the problems encountered in the prior art method. 
     It is an object of the present invention to provide an improved surge protector block assembly for use with a single and/or multi-layer printed circuit board which minimizes the use of board space and reduces undesired high inductance. 
     It is another object of the present invention to provide an improved surge protector block assembly which is adapted for surface mounting to a single and/or multi-layer printed circuit board. 
     It is still another object of the present invention to provide an improved surge protector block assembly which includes a plurality of individual 5-pin housing units each housing unit having surface mountable contacts for connecting electrically to conductive traces on a single and/or multi-layer printed circuit board via solder pads. 
     In a preferred embodiment of the present invention, there is provided a surge protector block assembly which includes a plurality of individual 5-pin housing units formed integrally together. Each of the plurality of individual housing units has a plurality of surface mountable socket contacts for receiving corresponding pins of a surge protector module. A single and/or multi-layer printed circuit board is provided with a plurality of solder pads for electrical connection to corresponding ones of the plurality of surface mountable socket contacts. An input connector socket is formed on the printed circuit board for receiving incoming tip and ring lines. An output connector socket is also formed on the printed circuit board for receiving outgoing tip and ring lines. 
     The printed circuit board is provided with a plurality of layers and has a plurality of conductive traces formed on the plurality of layers. Certain ones of the plurality of conductive traces establish electrical connections between corresponding ones of the solder pads and the input connector socket. Certain other ones of the plurality of conductive traces establish electrical connection between corresponding other ones of the solder pads and the output connector socket. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and advantages of the present invention will become more fully apparent from the following detailed description when read in conjunction with the accompanying drawings with like reference numerals indicating corresponding parts throughout, wherein: 
     FIG. 1 is a top plan view of a surge protector block assembly for use with a single and/or multi-layer printed circuit board, constructed in accordance with the principles of the present invention; 
     FIG. 2 is a side elevational view of the surge protector block assembly of FIG. 1; 
     FIG. 3 is a bottom plan view of the surge protector block assembly of FIG. 1; 
     FIG. 4 is a left end view of the surge protector block assembly of FIG. 1; 
     FIG. 5 is a cross-sectional view, taken along the lines  5 — 5  of FIG. 1; 
     FIG. 6 is a top plan view of a single and/or multi-layer printed circuit board having one housing unit mounted thereon in accordance with the present invention; 
     FIG. 7 is a cross-sectional view, taken along the lines  7 — 7  of FIG. 6; 
     FIG. 8 is a front plan view of one of the surface mountable socket contacts of the present invention; 
     FIG. 9 is a right side view of the socket contact of FIG. 8; 
     FIG. 10 is a top plan view of the socket contact of FIG. 8; and 
     FIG. 11 is a bottom plan view of the socket contact of FIG.  8 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     It is to be distinctly understood at the outset that the present invention shown in the drawings and described in detail in conjunction with the preferred embodiment is not intended to serve as a limitation upon the scope or teachings thereof, but is to be considered merely as an exemplification of the principles of the present invention. 
     Referring now in detail to the drawings, there is shown in FIGS. 1 through 5 a surge protector block assembly  10  for coupling a plurality of surge protector modules (not shown) to multi-line telecommunications cables, constructed in accordance with the principles of the present invention. The surge protector block assembly  10  is comprised of five individual 5-pin housing units  12   a - 12   e  which are formed integrally together in a laterally spaced-apart relationship. Each of the individual housing units  12   a - 12   e  is preferably made from a suitable plastic insulating material and the like. Since each of the housing units  12   a - 12   e  is identical in its construction, it is believed sufficient to describe in detail only one of them, such as housing unit  12   a.    
     As can best be seen in FIGS. 1,  3  and  5 , the housing unit  12   a  is formed of a rectangularly-shaped housing or enclosure  11  and includes a plurality of openings or holes  14  formed therethrough which extend from its top surface  16  to its bottom surface  18 . While the plurality of holes  14  are arranged in a generally C-shaped configuration (FIG.  1 ), it should be clearly understood that the configuration can be of any shape dependent upon the lay-out of the pins formed on the surge protector modules being used therewith. The bottom surface  18  of the housing unit  12   a  is formed with a mounting post  20  which is used to locate and position the housing unit  12   a  with respect to a single and/or multi-layer printed circuit board, as will be described more fully hereinafter. 
     A tubular-shaped surface mountable socket contact  22  is preferably formed of a metallic material such as a copper alloy and is inserted into each of the corresponding ones of the plurality of holes  14  of the housing unit  12   a . Each pin of the surge protector module fits into one of these surface mountable socket contacts  22  and forms with the socket contacts a compression fit so as to establish a good electrical connection. A plurality of such surge protector modules may be similarly inserted into the corresponding socket contacts  22  mounted in the other individual housing units  12   b  through  12   d  of the protector block assembly  10 . 
     As was previously mentioned, the conventional surge protector module in an industrial standard configuration has five (5) pins. Two of the five pins are connected to each of the incoming tip and ring lines. Two of the other five pins are also connected to each of the outgoing tip and ring lines. The remaining pin is connected to a ground potential. 
     With reference to FIG. 6, there is illustrated one of the individual housing units  12   a - 12   e , such as unit  12   a  of FIG. 1, which has been easily severed or broken apart at junction  24  (FIG. 2) so as to be separated from the surge protector block assembly  10  and which has been surface mounted onto a single and/or multi-layer printed circuit board  26 . The single and/or multi-layer printed circuit board  26  includes a drilled hole  28  for receiving the mounting post  20  of the individual housing unit  12   a  so as to locate and position the unit with respect to the printed circuit board. The single and/or multi-layer printed circuit board  26  also includes a plurality of solder pads  30  which are aligned so as to contactly engage with the lower ends of the surface mountable socket contacts  22 . 
     The multi-layer printed circuit board  26  is fabricated from multiple layers of a dielectric material such as fiber-glass which are then bound together. Each layer of the multi-layer printed circuit board is manufactured with a predetermined pattern of a plurality of metal conductive traces. Each of the conductive traces is used to provide a unique, low resistant electrical connection between one of the solder pads  30  and a corresponding one of the pins on either an input or output connector socket. The input connector socket is connectable to a cable having a plurality of incoming tip and ring telephone lines. The output connector socket is connectable to a cable having a plurality of outgoing tip and ring telephone lines. For example, the conductive trace  27   a  is used to form an electrical connection between the solder pad  30   a  and one pin on an input connector socket  29   a . Similarly, the conductive trace  27   b  is used to form an electrical connection between the solder pad  30   b  and one pin on an output connector socket  29   b.    
     As will be noted in FIG. 7 of the drawings, each of the surface mountable socket contacts  22  of the housing unit  12   a  is attached electrically to the top surface of the single and/or multi-layer printed circuit board  26  via the solder pads  30  by using a reflow solder process or the like. It will be appreciated that the lower ends of the socket contacts  22  are substantially flush with the bottom surface or side of the individual housing unit  12   a  so as to be surface mountable onto the printed circuit board  26 . 
     Unlike the prior art surge protector block assembly which is mounted to a multi-layer printed circuit board having a plurality of sockets or plated-through holes, the present invention allows the amount of space required for mounting the present surge protector block assembly to be reduced. Further, the instant invention will have less inductance effect at high frequencies due to the elimination of the plated-through holes. 
     The surface mountable socket contacts  22  shown generally in FIGS. 1,  3  and  5  are all identical and one of them is depicted in full detail in FIGS. 8 through 11. The upper section of the socket contacts  22  is formed of three equally-spaced arcuate members  32   a ,  32   b  and  32   c  which are separated by a corresponding one of a plurality of U-shaped slits  34   a ,  34   b  and  34   c . Below the U-shaped slit  34   b , the arcuate members  32   b  and  32   c  are separated by a small gap  36 . Extending downwardly and formed integrally with the lower portion of the arcuate member  32   a , there is provided a bight portion  37 . The bight portion  37  is connected integrally on its lower end to a semi-cylindrical member  38  via a small C-shaped portion  39 . The semi-cylindrical member  38  is formed with opposed flared end portions  40   a  and  40   b.    
     During assembly, twenty-five of the surface mountable socket contacts  22  are inserted into the corresponding openings  14  formed in the five 5-pin housing units  12   a - 12   b  so as to form the completely finished surge protector assembly illustrated in FIG.  1 . As will be noted from FIG. 5, the bottom surfaces  42  of the arcuate members  32   b  and  32   c  will come to rest against the top surface  44  of a semi-circular ledge  46 , which acts as a stop member, formed in the opening  14 . As a result, the top surface  48  of the arcuate members will be disposed slightly below the top surface  16  of the housing unit  12   a . On the other hand, the bottom surface of the semi-circular member  38  will be substantially flush with the bottom surface or side  18  of the housing unit  12   a . However, in practice, the bottom surface  50  of the member  38  will extend slightly below the bottom surface  18  so as to facilitate surface mounting of the housing unit  12   a  to the single and/or multi-layer printed-circuit board  26 , as shown in FIGS. 6 and 7. 
     From the foregoing detailed description, it can thus be seen that the present invention provides an improved surge protector block assembly which includes a plurality of individual 5-pin housing units formed integrally together. Each of the plurality of individual housing units has a plurality of surface mountable socket contacts for receiving corresponding pins of a surge protector module. A single and/or multi-layer printed circuit board is provided with a plurality of solder pads for electrical connection to corresponding ones of the plurality of surface mountable socket contacts. 
     While there has been illustrated and described what is at present considered to be a preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof without departing from the true scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the central scope thereof. Therefore, it is intended that this invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out the invention, but that the invention will include all embodiments falling within the scope of the appended claims.