Abstract:
A surface mount poke in connector is disclosed for mounting upon a surface of an electrical device such as printed circuit board, and is particularly applicable for printed circuit boards supporting LEDs. The connector includes a contact having an engaging mechanism for securing a first and second wire leads to the contact. The contact further has attachment points for connecting the connector to an electrical device surface by soldering.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part, and claims the priority of U.S. non-provisional patent application Ser. No. 11/615,235 filed on Dec. 22, 2006, incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention is directed to an electrical connector, and more specifically a feed-through surface mount electrical connector (SMEC) for connecting wire leads to an electrical device using surface mount technology (SMT). The electrical device may be a printed circuit board (PCB), but is not limited thereto. The PCB may contain light emitting diodes (LEDs). The invention is particularly well suited for connecting multiple PCBs in series. 
       BACKGROUND OF THE INVENTION 
       [0003]    Electrical devices are often attached to printed circuit boards (PCBs) by soldering terminals of the electrical device to a surface of the PCB. Surface Mount Technology (SMT) is a particular method of soldering electrical terminals to a PCB. SMT has been developed to affix electrical devices upon PCBs in an automated manner, but the devices may also be placed manually. SMT has reduced cost, improved reliability, and reduced the overall physical size of the PCB in many applications. SMT allows for mounting electrical devices on both sides of a PCB, which was not possible using through hole mounting technology. 
         [0004]    SMT is a method for constructing electronic circuits in which the components are mounted directly onto the surface of a PCB or other suitable component surface. SMT is a proven technology for creating electronic assemblies with higher packaging density when compared with comparable through-hole technology methods of PCB assembly. The components are typically mounted on the board by an automated method such as a robot assisted assembly line. Electrical points of contact between the components and the board may be treated with solder paste. Assembled PCBs may then be treated in a high temperature oven at temperatures of up to about 265° C. or higher to reflow the solder. The oven may be operated with an air atmosphere or under an inert atmosphere such as nitrogen. 
         [0005]    Electronic devices so made are called surface-mount devices (SMDs). SMT has largely replaced the previous construction method of fitting components with wire leads into holes in the circuit board, which is called through-hole technology. An SMT component is usually smaller than its leaded counterpart because it has no leads or smaller leads. It may have short pins or leads of various styles, flat contacts, a matrix of balls, or other terminations on the body of the component to assist with fixing the component to the board and/or establish an electrical connection between the board and the component. 
         [0006]    PCBs supporting light emitting diodes (LEDs) may be used to form light displays. Often, multiple LED lighting PCBs are coupled in series by two or more wires to form a string of PCBs. The string of PCBs provides for a flexible light source able to adapt to the contours of large letters used in signage. Current practice is to connect the wires to the PCBs by soldering the leads of the wires to the top surface of the PCB. The step of soldering the wire leads to the boards is time consuming and costly. 
         [0007]    In related patent application Ser. No. 11/615,235, a connector for attaching a wire lead to a PCB was disclosed that solved many of the problems of prior art connectors. This connector received a wire lead to be connected on one side of the connector. The connector was capable of receiving more than one wire lead, but the wire leads entered the connector from the same side. When using this connector to string PCBs in series, one connector would be used to receive and secure wires from an electrical device from a first direction, and another connector would be used to receive and secure wires from another electrical device from the opposite direction. Therefore, at least two connectors were necessary to provide an electrical connection in a series string of PCBs. 
         [0008]    Therefore, there is an unmet need to provide a single connector for securely connecting a first wire lead to an electrical device from a first direction and a second wire lead from a second electrical device from an opposite direction by a simple, reliable and cost effective process, such as a SMT automated process. The connector must approach the small physical size envelope of the wires to be soldered to the PCB so as not to shadow any neighboring components. 
       SUMMARY OF THE INVENTION 
       [0009]    This invention provides for a low profile feed-through surface mounted electrical connector (SMEC) for connecting at least two wire leads to a printed circuit board (PCB) or other suitable component surface. The low profile of the connector reduces shadowing by the connector when mounted on a PCB supporting LEDs. The SMEC is attached to the PCB by surface mount technology (SMT), a standardized automated process for placing and attaching electrical and electronic components to PCBs. Attachment may be by soldering, using a conductive adhesive, or other similar method. 
         [0010]    The connector is formed of a housing and a contact. The housing includes a first side having an opening for a first stripped wire lead to be inserted and securely connected to the contact and a second side opposite the first having an opening for a second stripped wire lead to be inserted and securely connected to the contact. The contact provides an electrical path from the first wire lead to the PCB and the second wire lead. The SMEC replaces a solder joint to connect wire leads to PCBs. 
         [0011]    The connector may be attached to the PCB by conventional SMT techniques. The connector may be attached to the PCB by soldering the contact to the PCB surface. Alternatively, the SMEC may be attached to the surface of the PCB by the use of a conductive adhesive or solder paste or similar attachment method. 
         [0012]    In an exemplary embodiment, the connector includes a housing having a recess configured to receive and secure a contact, a pair of openings in the housing for receiving a first wire and a second wire, a contact within the housing for receiving and securing the first wire and the second wire. The contact includes an attachment point for attaching the electrical connector to an electrical device and provides an electrical connection between the first wire and the second wire. The contact further includes a wire engaging mechanism for securing the first wire and the second wire to the contact. The wire engaging mechanism is a lance formed into the contact. 
         [0013]    The contact may be formed by first forming a predetermined shape from a conductive sheet and then forming the predetermined shape into a cylindrical, rectangular, square or other geometry with extended attachment points. The first forming may be stamping. The conductive sheet may be formed of a phosphor bronze metal sheet with a tin plating. 
         [0014]    The housing includes a stop for prohibiting the movement of the first wire and the second wire beyond a predetermined distance into the housing and the contact comprises a slot for receiving the stop. The stop may be a tab formed on an inside surface of the recess of the housing. Alternatively, the stop may be an indent or a slot having a spar formed into the contact. 
         [0015]    The connector further includes a housing having two recesses and two contacts. The attachment points may include a beveled portion for improving solder reflow during soldering to a printed circuit board. The attachment points may be directed downward away from the housing to allow the attachment points to be inserted into printed circuit board through-holes. 
         [0016]    An exemplary embodiment of a contact for creating an electrical connection between a first wire and a second wire is disclosed that includes a first receiving portion for securing a wire lead of the first wire and a second receiving portion for securing a wire lead of the second wire. The contact further includes a first engaging mechanism for securing the first wire lead into the contact and a second engaging mechanism for securing the second wire lead into the contact. 
         [0017]    The contact also includes an attachment point for attaching the contact to a substrate. The attachment point may be capable of being soldered to the surface of an electrical device or pushed through a through-hole of an electrical device. 
         [0018]    The first and second engaging mechanisms of the contact are a first and second lance formed into the contact. The lance may have a sharp edge for engaging the wire lead. 
         [0019]    An exemplary embodiment of an electrical device system includes an electrical device with a surface having an electrical pathway, and an electrical connector connected to the electrical device surface. The electrical connector includes a housing and a contact. The housing includes a recess configured to receive and secure the contact and a pair of openings in the housing for receiving a first wire and a second wire. The contact receives and secures the first wire and the second wire to the connector. 
         [0020]    The contact includes an attachment point for attaching the electrical connector to an electrical device and provides an electrical connection between the first wire, the second wire and the electrical pathway. 
         [0021]    The electrical device of the electrical device system may be a printed circuit board. The contact includes a wire engaging mechanism for securing the first wire and the second wire to the contact. The electrical connector may be connected to the electrical device surface by soldering. 
         [0022]    In the exemplary embodiments, the housing may be formed of a high temperature material that is lightweight and high strength, and able to operate in a high temperature environment, such as along the surface of a PCB that supports LEDs. The housing may be formed of a high temperature liquid crystal polymer (LCP) such as Zenite 6330® by E.I. du Pont de Nemours and Company of Wilmington, Del. or a high temperature nylon such as Stanyl 46 HF® by DSM Engineering Plastics North America, Inc., based in Reading, Pa., or any other known industry acceptable non-conductive high temperature resin. The housing is designed with a low profile and small footprint so that it may be placed upon a PCB supporting lighting LEDs without shadowing or blocking the light emissions of the LEDs. The housing at least partially covers the contact. 
         [0023]    The contact has a generally cylindrical geometry. The receiving sections of the contact may have an oval cross-section while the barrel sections of the contact have a circular cross-section. The contact is formed of a conductive material, which provides an electrical connection from the wire leads to the PCB. For example, the contact may be formed of a phosphor bronze metal with a tin plating or other known industry acceptable conductive metal and plating. 
         [0024]    The contact may be formed by first forming a predetermined shape from a conductive sheet and then forming the predetermined shape into a generally cylindrical geometry with extended attachment points. The first step in forming the contact is to stamp, cut or by other similar shaping methods form a predetermined shape from stock material. The stock material may be plated. Then, the predetermined shape is formed into the contact with extended attachment points by any material shaping method, including rolling and working. A combination of different shaping techniques may be used to complete the contact design. The extended attachment points of the contact may be provided with a beveled edge to assist in solder reflow during attachment to the PCB. Beveling the edge of the attachment points is important when pre-plated stock material is used to improve solder reflow. 
         [0025]    The contact is formed with an engaging mechanism. The engaging mechanism is a lance, pin or other similar shape for firmly securing the wire lead within the barrel. The lance may be formed into the contact during the forming of the predetermined shape. The lance may be shaped so as to provide for an edge to engage the wire lead within the barrel. The lance may be placed at any radial location on the contact except for where forming seams are prohibitive. The lance is preferably placed on the bottom of the contact. Superior retention performance has been observed with the lance placed on the bottom since the electrical device acts as a stop to lance deformation. 
         [0026]    Further aspects of the method and system are disclosed herein. The features as discussed above, as well as other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  illustrates an exemplary embodiment of a connector. 
           [0028]      FIG. 2  illustrates a cut-away top perspective view of the exemplary embodiment of a connector 
           [0029]      FIG. 3  illustrates a bottom perspective view of an exemplary embodiment of a connector. 
           [0030]      FIG. 4  illustrates a detailed bottom view of an exemplary connector housing. 
           [0031]      FIG. 5  illustrates a detailed view of an exemplary contact. 
           [0032]      FIG. 6  illustrates a detailed view from a bottom perspective of an exemplary contact. 
           [0033]      FIG. 7  illustrates a detailed view of an alternative exemplary contact. 
           [0034]      FIG. 8  illustrates a detailed view of another alternative exemplary contact. 
           [0035]      FIG. 9  illustrates a partial cutaway view of the another alternative exemplary contact of  FIG. 8 . 
           [0036]      FIG. 10  illustrates a detailed view of yet another alternative exemplary contact. 
           [0037]      FIG. 11  illustrates a sectional view of the yet another alternative exemplary contact of  FIG. 10 . 
           [0038]      FIG. 12  illustrates an exemplary electrical device system. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0039]    The present invention now will be described more fully hereinafter with reference to the accompanying drawings in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. 
         [0040]    Referring to  FIG. 1 , an exemplary embodiment of the feed-through surface mount poke-in electrical connector  100  is depicted. The connector  100  provides a first electrical connection to a first pair of wires that includes a first wire  110  and second wire  120 , and a second electrical connection to a second pair of wires that includes a third wire  130  and a fourth wire  140 . The connector  100  may also connect the first wire  110  and the second wire  120  to an electrical trace (not shown) on an electrical device such as a PCB. In a similar manner, the connector  100  may also connect the third wire  130  and the fourth wire  140  to a second electrical trace (not shown) on an electrical device such as a PCB 
         [0041]    A cut-away top view of the connector  100  is shown at  FIG. 2 . As can be seen in  FIG. 2 , the connector  100  includes a housing  200 , a first contact  300 , and a second contact  301 . As can be further seen in  FIG. 2 , the first wire  110  includes a first sheathed section  212  and a first conductor  214 . The second wire  120  includes a second sheathed section  222  and a second conductor  224 . The third wire  130  includes third sheathed section  232  and a third conductor  234 . The fourth wire  140  includes a fourth sheathed section  242  and a fourth conductor  244 . The wire conductors  214 ,  224 ,  234 ,  244  may be a solid wire, a fused stranded wire, a stranded wire, a stranded twisted wire, or any other suitable wire configuration. As can be also seen in  FIG. 2 , the housing  200  includes stops  202  that at least partially bisect the first contact  300  and the second contact  301  and prohibit the movement of the wires  110 ,  120 ,  130 ,  140  beyond a predetermined distance into the housing  200 . The stops  202  provide a barrier to the wire conductors ( 214 ,  224 ,  234 ,  244 ) that prohibit movement beyond the stops  202 . 
         [0042]    It should be appreciated, that while the exemplary embodiment is depicted having two contacts  300 ,  301 , the connector may be configured with only a single contact  300  to provide an electrical connection to a first wire  110  and a second wire  120 , or the connector  300  may be configured with more than two contacts  300 ,  301  to provide an electrical connection to more than two pairs of wires. 
         [0043]    A bottom view of the connector  100  is shown at  FIG. 3 . As can be seen in  FIG. 3 , the contacts  300 ,  301  include attachment points  310 . Attachment points  310  allow the connector  100  to be physically and electrically attached to a PCB by conventional SMT methods such as soldering. The shape of the attachment point  310  may vary depending upon the surface area desired to be in contact with the PCB surface. 
         [0044]    A detailed view of the bottom of the housing  200  is shown at  FIG. 4 . As can be seen in  FIG. 4 , the housing includes a first recess  400  for receiving the first contact  300  and a second recess  401  for receiving the second contact  301 . The stops  202  are also shown in more detail in  FIG. 4 . As can be seen in  FIG. 4 , the stops  202  are tabs formed on an inside surface of the recesses  400 ,  401 . The housing  200  also includes slots  410  that allow attachment points  310  to extend out of the housing  200 . The housing  200  further includes nibs  420  for securing the first contact  300  and the second contact  301  to the housing  200 . The housing  200  also includes openings  415  that allow the wires ( 110 ,  120 ,  130 ,  140 ) to enter the housing  200 . The stops  202  can also be seen in  FIG. 4 . 
         [0045]    The housing  200  is formed of a high temperature dielectric polymer. The polymer may be a high temperature liquid crystal polymer such as Zenite 6330® by E.I. du Pont de Nemours and Company of Wilmington, Del. or a high temperature nylon such as Stanyl 46 HF®. The housing  200  may also be formed of any other known industry acceptable non-conductive high temperature resin. The heat resistance of the housing  200  allows the attachment points  310  to be connected to a PCB surface (not shown) at the temperatures used to reflow solder without damage or distortion. The housing  200  may be formed by any known plastic forming method such as injection molding. 
         [0046]    A detailed view of a first contact  300  from a top perspective is shown in  FIG. 5 . The second contact  301  (see  FIG. 2 ) is similarly configured. The contact  300  includes a first receiving section  510 , a first barrel section  520 , a second receiving section  530  and a second barrel section  540 . The diameter of the first receiving section  510  and the second receiving section is selected to allow for the insertion of the first sheath section  212  and the second sheath section  222  (see  FIG. 2 ), respectively. The first barrel section  520  and the second barrel section  540  have a diameter that allows for the insertion of the first wire conductor  214  and the second wire conductor  224  (see  FIG. 2 ), respectively. In this exemplary embodiment, the first receiving section  510  and the second receiving section  530  have a generally circular cross-section. The first barrel section  520  and the second barrel section  540  have a generally oval cross-section. Alternatively, the first barrel section  520  and the second barrel section  540  may have a generally circular cross-section. 
         [0047]    The contact  300  also includes a slot  550  for receiving a stop  202  of the housing  200  (see  FIG. 4 ). The contact  300  also includes attachment points  310  as shown. Attachment points  310  may be attached to a surface of an electrical device by soldering, conductive paste, or other known attachment methods. The first receiving section  510  and the second receiving section include an orientation notch  515  to assist in mating the contact  300  with the housing  200 . Alternatively, the contact  300  may not be provided with the notch  515 . 
         [0048]    An exemplary embodiment of a method of forming the contact  300  will now be discussed. The contact  300  was formed by first stamping out a flat pattern blank from a tin plated phosphor bronze sheet. The sheet was a phosphor bronze metal of about  320  microns thick with a tin plating of about 3.0 to about 4.0 microns. It should be noted that the invention is not limited to this sheet or plating thickness, and that thinner or thicker sheet and plating may be selected as determined by the wire gauge and application. The flat pattern blank was then partially rolled and worked to form the contact  300 . 
         [0049]    A detailed view of the contact  300  from a bottom perspective is shown in  FIG. 6 . As can be seen in  FIG. 6 , the contact  300  includes a first lance  610  for securing the first wire  110  (see  FIG. 2 ) and a second lance  620  for securing a second wire  120  (see  FIG. 2 ). The second lance  620  is provided with a beveled edge  630  to assist in securely engaging an inserted wire conductor. The first lance  610  is similarly provided with a beveled or sharp edge (not shown). Alternatively, the first lance  610  and the second lance  620  may not be provided with a beveled edge  630 . 
         [0050]    A detailed view of an alternative embodiment of a first contact  700  is shown in  FIG. 7 . As can be seen in  FIG. 7 , the contact  700  is formed similarly to the contact  300  ( FIG. 5 ), except that the attachment points  710  are turned downward. In this configuration, the contact  700  may be attached to an electrical device by press-fitting the attachment points  710  into through-holes of an electrical device. 
         [0051]    A detailed view of another alternative embodiment of a first contact  800  is shown in  FIG. 8 . The contact  800  has a generally cylindrical geometry. The contact  800  includes an indent  850 . The indent  850  may also be formed into the opposite side of the contact  800  (not shown). The indent  850  divides the contact  800  into a first barrel section  810 , a first receiving section  820 , a second barrel section  830  and a second receiving section  840 . The first barrel section  810  and the second barrel section  830  have a generally cylindrical cross-section. The first receiving section  820  and the second receiving section  840  have a generally oval cross-section as shown. Alternatively, the first receiving section  820  and the second receiving section  840  may have a generally circular cross-section. The contact  800  also includes attachment points  805  and orientation notches  807 . 
         [0052]    The configuration of the indent  850  can be seen more clearly in the partial cutaway view of contact  800  as shown in  FIG. 9 . The indent  850  extends into the contact  900  and is configured to prohibit the first conductor  214  (see  FIG. 2 ) from being inserted past a predetermined distance through the first receiving section  820  and to prohibit the second conductor  224  (see  FIG. 2 ) from being inserted past another predetermined distance through the second receiving section  840 . Alternatively, the indent  850  may be placed in a single position or in more than two positions in order to prevent the first conductor  214  and the second conductor  224  from being inserted past a predetermined distance. 
         [0053]    As can further be seen in  FIG. 9 , the contact  800  includes a first lance  910  for securing the first wire  110  (see  FIG. 2 ) and a second lance  920  for securing a second wire  120  (see  FIG. 2 ). The first lance  910  and the second lance  920  may be provided with a beveled edge (not shown) to assist in securely engaging an inserted wire conductor. Alternatively, the first lance  910  and the second lance  920  may not be provided with a beveled edge. 
         [0054]    A detailed view of yet another alternative embodiment of a contact  1000  is shown in  FIGS. 10 and 11 .  FIG. 10  shows a contact  1000  from a perspective view.  FIG. 11  shows a sectional view of contact  1000  from the opposite side. The contact  1000  has a generally cylindrical geometry. The contact  1000  includes a slot  1050  formed into the contact  1000  as shown in  FIG. 10 . The contact  1000  also includes attachment points  1005  and orientation notches  1007 . 
         [0055]    As shown in  FIG. 11 , the slot  1050  includes a spar  1055  that is formed when the slot  1050  is formed into the contact  1000 . The spar  1055  is located approximately at the axial midpoint of the contact  1000 . The spar  1055  divides the contact  1000  into a first barrel section  1010 , a first receiving section  1020 , a second barrel section  1030  and a second receiving section  1040 . The first barrel section  1010  and the second barrel  1030  section have a generally cylindrical cross-section as shown. The first receiving section  1020  and the second receiving section  1040  have a generally oval cross-section. Alternatively, the first receiving section  1020  and the second receiving section  1040  may have a generally circular cross-section. The spar  1055  prohibits a first conductor  214  (see  FIG. 2 ) from being inserted past a predetermined distance in the first receiving section  1020  and prohibits a second conductor  224  (see  FIG. 2 ) from being inserted past a predetermined distance in the second receiving section  1040 . 
         [0056]    As can further be seen in  FIG. 11 , the contact  1000  includes a first lance  1110  for securing the first wire  110  (see  FIG. 2 ) and a second lance  1120  for securing a second wire  120  (see  FIG. 2 ). The first lance  1110  and the second lance  1120  are provided with a beveled edge  1130  to assist in securely engaging an inserted wire conductor. Alternatively, the first lance  1110  and the second lance  1120  may not be provided with a beveled edge  1130 . 
         [0057]    The connector  300  allows for the electrical connection of two wire conductors to each other as well as the PCB without having to solder the wire leads to the PCB or the connector  300 . The housing  200  was designed with a low profile and small footprint so that it could be placed upon a PCB supporting lighting LEDs without shadowing or blocking the light emissions of the LEDs. 
         [0058]      FIG. 12  illustrates an exemplary electrical device system  1200  that includes a connector  100  attached to an electrical device  1205 . The connector  100  includes attachment points  310 . The electrical device  1205  includes contact pads  1207 . The contact pads  1207  may provide an electrical connection to further electrical pathways (not shown) of the electrical device  1205 . The electrical device  1205  may be a PCB. The electrical device  1205  may be of similar overall size as the connector  100 , or the electrical device  1205  may be of a much larger overall size compared to the connector  100 . The connector  100  is attached at the attachment points  310  to the contact pads  1207  by soldering, however, other methods including using a conductive adhesive, or other similar method may be used. 
         [0059]    The connector  100  provides an electrical connection between a first wire  1210  and a second wire  1220 . The connector  100  may further provide an electrical connection between the first wire  1210  and the second wire  1220  and the electrical device  1205  through the attachment points  310  and the contact pads  1207 . Alternatively, the first wire  1210  and the second wire  1220  may be physically attached to the electrical device  1205  at the attachment points  310  and contact pads  1207 , but the contact pads  1207  may not provide further electrical connection to the electrical device  1205 . Similarly, the connector  100  provides an electrical connection between a third wire  1230  and a fourth wire  1240 . The connector  100  may also provide an electrical connection between the third wire  1230  and the fourth wire  1240  and the electrical device  1205  through the attachment points  310  and the contact pads  1207 . Alternatively, the third wire  1230  and the fourth wire  1240  may be physically attached to the electrical device  1205  at the attachment points  310  and contact pads  1207 , but the contact pads  1207  may not provide an electrical connection to the electrical device  1205 . 
         [0060]    While the exemplary electrical device is shown with a single connector  100  upon the electrical device  1205 , it should be understood that more than one electrical connector  100  may be attached to the electrical device  1205 , and that any number of the pads  1207  may provide further electrical connection to the electrical device  1205  or any number of the pads  1207  may be used only as a physical connection. 
         [0061]    While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the 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 essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.