Abstract:
There is provided an insulation displacement connector (IDC) assembly having a main body defining at least one wire channel. The main body has at least one substantially flat surface to which a vacuum nozzle can be affixed in order to pickup the IDC assembly. The IDC assembly has at least one contact member with a piercing, cutting or slicing end that is slideably disposed within the main body, and a mounting end that extends from the main body. The mounting end of the contact is attached to a printed circuit board. An insulated conductor, such as wire, cable, and/or ribbon, can be quickly and easily inserted in the channel without being pierced by the piercing end of the contact. When a user pushes down on the IDC, the contact slides into the channel and pierces the insulated conductor.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention generally relates to electrical connectors and, in particular, to insulation displacement connectors for surfaces mounted on a printed circuit board (PCB). 
     2. Description of the Related Art 
     An insulation displacement connector (IDC) forms a connection with an insulated conductor, such as a wire, by using a contact that can pierce the insulation to make contact with and connect to the conductor. IDCs are used extensively in the telecommunications industry because they can very quickly terminate a large number of wires. For the same reason, IDCs are now increasingly used on printed circuit boards (PCBs). 
     Insulation displacement connectors have become popular because they are highly economical and a cost-effective method for performing wire terminations. No wire or cable preparation is required. IDCs are designed to reduce wire termination cost by elimination the need to remove the insulation from the wire before terminating it. When a wire is inserted into the IDC slot, the piercing contacts cut and displace the wire insulation and pierce it and make contact with the conductor wires surrounded by the insulation. 
     Many designs for IDCs are known in the art. However, these known IDCs are unsuitable for use with surface mounting technology (SMT). SMT generally requires that an electrical contact be compact in size and light in weight and have a small footprint. The electrical contact must also be heat resistant and compatible with common soldering techniques used in SMT. In addition, since the most common pickup mechanism is a vacuum nozzle of a pick-and-place machine, it is desirable that electrical contacts for surface mounting have at least on suitable flat surface to which a vacuum nozzle can abut against and apply a sufficient vacuum for effective pickup. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an insulation displacement connector for surface mounting on a printed circuit board using an automatic pick-and-place machine. 
     It is also an object of the present invention to provide such an insulation displacement connector that is compact in size with a small footprint for surface mounting on a printed circuit board. 
     It is another object of the present invention to provide such an insulation displacement connector that is light in weight for surface mounting on a printed circuit board. 
     It is a further object of the present invention to provide such an insulation displacement connector that is heat resistant for surface mounting on a printed circuit board. 
     It is yet another object of the present invention to provide such an insulation displacement connector for surface mounting on a printed circuit board that is compatible with common soldering techniques. 
     It is an additional object of the present invention to provide such an insulation displacement connector for surface mounting on a printed circuit board that has at least one sufficiently large, flat surface to which a vacuum nozzle can affix itself. 
     It is still another object of the present invention to provide an insulation displacement connector that can make a connection with insulated multiple fine wire conductors in a short time with minimal labor. 
     These and other objects are achieved by an insulation displacement connector (IDC) assembly according to the present invention. The IDC assembly has a main body defining at least one wire channel. In addition, the main body has at least one substantially flat surface to which a vacuum nozzle may be affixed in order to pick up the IDC assembly. The IDC assembly has at least one contact member with a piercing, cutting or slicing end that is slideably disposed within the main body, and a mounting end that extends from the main body. The mounting end of the contact is attached to a printed circuit board. An insulated conductor, such as a wire, cable and/or ribbon, can be quickly and easily inserted in the channel without being pierced by the piercing end of the contact. When a user pushes down on the IDC, the contact slides into the channel and pierces the insulated conductor. 
     In a presently preferred embodiment, the IDC comprises a surface mount IDC connector for attaching wires to a printed circuit board, including a housing having a number of generally parallel wire-receiving channels at least equal to the number of wires to be connected and generally defining, when the connector is mounted on a printed circuit board (PCB), a plane substantially parallel to the surface of the PCB on which the connector is mounted, said wire receiving channels being dimensioned to receive the wires with little clearance to thereby generally fix the physical positions of the wires against lateral or transverse shifting. Said housing further includes a number of slots corresponding to the number of said channels, each slot being substantially normal to said plane and aligned with and communicating with an associated channel. A plurality of piercing blade assemblies are provided, one received in each of said slots, each piercing blade assembly including at least one piercing blade receivable into a slot for movement through a slot and being at least partially receivable within an associated channel, said piercing blades having a length greater than the dimension of said slots in said normal direction and including a soldering portion positioned beyond said housing when said piercing blades are fully moved into said channels, whereby insertion of said piercing blades through the insulation of wires within said channels pierces the wires while leaving said soldering portions exposed outside said housing for soldering to a PCB. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects and features of the present invention may become clear from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of an insulation displacement connector block according to the present invention; 
         FIG. 2  is a front elevational view of the insulation displacement connector housing block of  FIG. 1 ; 
         FIG. 3  is a bottom plan view of the insulation displacement connector block of  FIG. 1 ; 
         FIG. 4  is a cross sectional view of the block shown in  FIG. 3 , taken along line  1 - 4 . 
         FIG. 5  is a perspective view of a piercing blade assembly for use with the block shown in  FIGS. 1-4 ; 
         FIG. 6  is an enlarged side elevational view of the blade assembly shown in  FIG. 5 ; 
         FIG. 7  is an end elevational of the blade assembly shown in  FIG. 6 ; 
         FIG. 8  is an enlarged view of the piercing tips of the blade assembly shown in the detail A in  FIG. 7 ; 
         FIG. 9  is similar to  FIG. 4  also showing a blade assembly of  FIGS. 5-8  at least partially inserted into a slot of the connector block; 
         FIG. 10  is similar to  FIG. 2  shown with four blade assemblies partially inserted into the connector block; 
         FIG. 11  is similar to  FIG. 3  showing the blade assemblies inserted into the slots of the connector block; 
         FIG. 12  is a perspective view of the block shown in  FIG. 10  with conductors inserted into a plurality of the wire receiving channels; and 
         FIG. 13  is similar to  FIG. 2  but showing the insulation displacement connector positioned on a PCB for attachment thereto. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now specifically to the attached figures, in which the same or similar parts will be designated by the same reference numerals throughout, and first referring to  FIGS. 1 and 12 , an insulation displacement connector (IDC) assembly is generally designated by the reference numeral  10 . 
     The IDC connector assembly  10  is especially suitable for terminating one or a number of fine wires to a surface mount (SM) IDC connector. 
     The IDC connector assembly  10  includes a housing block  12  which is typically formed or molded from a suitable plastic material, as will be discussed. The housing block or housing has a generally rectangular receptacle  14  in which there is formed a wire-receiving opening  16 . When the IDC connector assembly  10  is mounted on a printed circuit board (PCB) the wire-receiving opening  16  is generally parallel to the mounting surface on the PCB. While the wire-receiving opening may be closed at one end, so that wires can only be received or inserted through the other end, in the presently preferred embodiment, the wire-receiving opening  16  is a through opening open at both ends of the receptacle  14 . 
     The wire-receiving opening  16  is configured to create one or more generally parallel wire-receiving channels  18  the number of which is at least equal to the number of wires to the terminated or connected to the housing block  12 . Referring to  FIG. 4 , for example, each wire-receiving channel  18  has opposing openings  18   a ,  18   b  through which wires to be terminated can be inserted. The wire-receiving channels  18  are dimensioned to receive wires with little clearance to thereby generally fix the physical positions of the wires against lateral or transverse shifting, as suggested in  FIG. 12 . Such alignment or fixing of the wires is facilitated by means of a plurality of internal alignment ridges  20  which help to position and maintain the wires against lateral shifting, as suggested in  FIGS. 2 ,  10 ,  12  and  13 . 
     To one side of the receptacle  14  there is provided a pressure plate or shoulder  22  which exhibits an exposed flat pickup/pressure surface  22 ′. As suggested in  FIG. 13 , the flat pickup surface  22 ′ is suitable for cooperation with a vacuum nozzle (not shown) of a pick-and-place machine which can cooperate with the flat surface  22 ′ for picking up and placement of the housing block  12  at a suitable location on a PCB. 
     At the opposing surface from the flat pickup surface  22 ′ there are provided a plurality of piercing blade slots  26  the number of which corresponds to the number of wire-receiving channels  18 . Each slot  26  is substantially normal to the plane defined by the wire-receiving opening  16  and aligned to communicate with an associated channel  18 . As best shown in  FIGS. 2 ,  4 ,  9  and  10 , the slots  26  have lateral guide edges  26   a ,  26   b  and extend to and communicate with the wire-receiving opening  16 . 
     One or more piercing blade assemblies  30  are provided one receivable in each of the slots  26 . Each piercing blade assembly includes at least one piercing blade  38  receivable into a slot  26  for movement through a slot and being at least partially receivable within an associated wire-receiving channel  18 . The piercing blades  38  have a length greater than the dimension of the slots  26  in the normal direction and include a soldering portion including an edge surface  38 ′ positioned beyond the receptacle  14  when the piercing blades are fully moved into or inserted into the wire-receiving channels  18 . It will be evident, therefore, that the insertion of the piercing blades  38  into the channels pierces or displaces the insulation of wires that are within the wire-receiving channels  18  while leaving the soldering edges or surfaces  38 ′ exposed outside of the housing block  12  or receptacle  14  for soldering to a PCB, as shown and suggested in  FIGS. 12 and 13 . 
     The piercing blade assemblies  30  may be produced as a continuous strip  28 , as shown in  FIG. 6 , successive piercing blade assemblies being connected to each other by a connecting strip or tab  32  which also serves as a stop portion for preventing excessive insertion of the piercing blades into the receptacle  14 . A notch  34  is preferably provided centrally between each connecting strip  32  to facilitate separation of the piercing blade assemblies from each other. The inner edge surface  36  of each stop portion engages the receptacle  14  to prevent further penetration of the piercing blade assemblies  30  into the block once sufficient penetration has taken place to effectively pierce and displace the insulation to make contact with the internal wires of the conductors. 
     Referring to  FIGS. 7 and 8 , each piercing blade assembly  30  preferably includes a plurality of substantially co-planar piercing blades  38  that extend along the lengths of the wire-receiving channels  18 . Successive ones of the blades  38  are preferably slightly offset to opposite sides of a plane defined by the co-planar piercing blades to ensure that the captured conductor and its insulation sheath are not urged to one side or the other during the penetration of the blades but, instead, the offset blades have the effect or tendency to apply forces on the conductor that maintains its position centrally within the channels to ensure reliable penetration and electrical contact with the inner conductive wires. 
     In accordance with one feature of the invention, each piercing blade assembly  30  includes a plurality of substantially co-planar piercing blades  38 , as aforementioned, that have a dimension substantially corresponding to the dimension of the slots  26  along the direction of the wire-receiving channels  18 . Unidirectional material engaging means are preferably provided for engaging a material surface of the slots and permitting the piercing blade assemblies to be urged into the slots while preventing a piercing blade assemblies from being removed from the slots by providing significantly less resistance of movement during insertion then during extraction or removal of the piercing blade assemblies. Referring to  FIGS. 6 and 9 , the end piercing blades  38 , at the beginning and the end of each series of such blades, is provided with laterally protruding portion  44 , in the form of a barb or spike, that cooperates with a receiving recess  46  for receiving displaced plastic material of the receptacle  14 . The protruding portion  44  points slightly outwardly and upwardly, as viewed in  FIG. 6 , so that insertion of the piercing blade assembly  30  as in  FIG. 9  provides some resistance due to the lateral engagement and resulting friction between the protruding portions  44  and the surfaces at the ends of the slots which make contact therewith. Once some of the plastic material in the slot is removed or displaced it may be received within the receiving recesses  46 . While application of a predetermined amount of pressure permits the piercing blade assembly  30  to be inserted into an associated slot  26 , removal becomes more difficult if not impossible because of the orientation of the protruding portion  44  since the resulting resistance is significantly greater for removal then for insertion. This ensures that once the piercing blade assembly has been inserted and penetrates the conductor that it remains in its final position and can not inadvertently be removed from an associated slot. Referring to  FIG. 11 , for example, the width W of the housing block  12  is slightly larger then the width W′ of the receptacle  14 . This provides a slightly greater surface  22 ′ for application of pressure by a press or other suitable insertion tool. 
     Referring to  FIG. 13 , housing block  12  is adapted to reduce the amount of space occupied by the IDC  10  when it is mounted on a PCB. The block  12  has a width W ( FIG. 11 ) which is a function of the number of slots  26 . The block  12  may have any shape depending on the specific application, such as cylindrical or rectilinear. As shown, block  12  is generally rectilinear or rectangular in shape. The length L along the directions of the slots  26  may be about 0.223 inches long. The width W′ may be about 0.225 inches wide between the left and the right lateral surfaces. 
     The block  12  has a shoulder  22  having an exposed flat surface  22 ′ that is relatively broad and flat so that a vacuum pickup nozzle can effectively fasten itself thereto. This is a significant aspect of the present invention because it allows the IDC  10  to be handled by automated pick-and-place machines. The shoulder  22  may have any shape depending on the specific application, such as cylindrical or rectilinear. The shoulder  22  may have a similar or different shape compared to the block  12 . As shown, shoulder  22  is generally rectangular in shape. 
     The surface  22 ′ may be about 0.225 inches in length and about 0.283 in width. The top surface  22 ′ has an area that is preferably larger than the area of the bottom surface  14 ′. At its tallest point, IDC  10  is about 0.130 inches tall between the top surface  22 ′ and the bottom surface  14 ′. 
     The wire channel  18  may be about 0.040 inches to about 0.043 inches in diameter. To facilitate the insertion of a wire into wire channel  18 , the entrance portions  18   a  and  18   b  preferably flared outwardly or have a diameter that is slightly larger than the diameter of the remainder of the wire channel  18 . 
     IDC  10  is preferably attached to a PCB using surface mounting technology. Accordingly, IDC  10  is specifically shaped to be releasably held by a vacuum nozzle of an automated pick-and-place machine. As stated above, top surface  22 ′ is preferably broad and flat to facilitate adequate suction from the vacuum nozzle, so that IDC  10  can be picked-up. Alternatively, top surface  22 ′ may have a lip and/or a groove shaped to mate and/or coordinate with the vacuum nozzle. For example, top portion  22  may have a raised portion or tab that extends a short distance into the opening of the vacuum nozzle. Further details of pick-and-place machines, in particular, and surface mounting technology, in general, are described in U.S. Pat. Nos. 5,605,403 and 5,730,608, which are incorporated herein by reference in their entirety. To mount IDC  10  on a PCB, vacuum nozzle of an automated pick-and-place machine is releasably affixed to top side  22 ′. IDC  10  is placed on the PCB in such a manner that the edge surfaces  24 ′ of the contacts or blades  38  are positioned on a PCB land or pad. Reflow soldering melts the metal of the PCT land and subsequent cooling of the melted metal forms a bond between blade  38  and the PCB. 
     As shown in  FIG. 10 , the blades  38  initially do not extend into channels  18 . In this way, a wire may be relatively easily and quickly inserted into the channels  18  without being impeded by the blades  38 . A wire W may be inserted into the channel  18  either before or after IDC  10  is mounted on a PCB. Preferably, the IDC  10  is mounted on a PCB before a wire is inserted into channels  18 . Once IDC  10  is mounted on a PCB and a wire is inserted into a channel  18 , a user or suitable tool may push down on IDC  10 , which forces the block  12  to slide along relative to the blades  38  within slots  24 , whereby the piercing tips  42  of blades  38  extend into channels  18 . Thus, the piercing portion or tips  42  of blades  38  are made to pierce or cut the insulation of an insulated wire in the channels  18  and, ultimately, touch the conductive material or metal in the center of the wire, whereby an interconnection is formed between the PCB and the wire. Of course, if non-insulated (e.g., a bare metal wire) is terminated the conducting material or metal will be directed pushed against or into blades  38 . The blades  38  may also actually bite or cut into the conducting material or metal in the center of the wire to form a potentially “gasless” connection. 
     In use, the piercing blade assemblies  30  are at least partially inserted into the associated slots  24  and the IDC connector assembly  10  is positioned on associated lands or pads  50  of a PCB  48  as shown in  FIG. 13 . Any suitable and conventional soldering technique may be used to secure the edge surfaces  24 ′ to the PCB to affix the housing block  12  as shown. Wires w are then inserted into the wire-receiving channels  18  as suggested in  FIG. 12 . Once the wires are in place, suitable pressure may be applied to upper surface  22 ′ to urge the entire housing block  12  downwardly in the direction of the PCB  48 . In doing so, the piercing blade assemblies  30  are forced to further penetrate into the slots  24  and ultimately into the wire-receiving channels  18  until the piercing tips  42  pierce the wires w and make contact therewith. Thus, by a single application of a suitable downward force on the housing block  12  all of the wires w to be terminated are simultaneously pierced and suitably and reliably contacted. The IDC connector assembly  10  is preferably placed on a PCB  48  and soldered thereto prior to insertion of the wires, this permitting the use of pick-and-place equipment, it is also possible to use the IDC connector assembly in applications that do not involve automated pick-and-place equipment. In some cases, the IDC connector assembly  10  can also be used to insert the wires into the wire-receiving channels  18 , causing the piercing blades  24  to pierce the conductors and then the assembly mechanically connected such as by soldering, to a PCB. However, the greatest application is with automated equipment and the assembly is particularly adapted for surface mounting of connector assemblies for terminating fine wire conductors. 
     While the invention has been shown and described in connection with a preferred form of an embodiment it will be understood that modifications may be made without the departure from the scope or spirit of the invention.