Abstract:
A method of creating a sealed, un-mated electrical connector system using single insertion press-fit pins. Using single insertion press-fit pins allows for use of simple plastic parts for the connector shroud and a true position assurance comb in conjunction with single insertion press-fit pins. The result is a lower cost for the final connector assembly. Less plastic is needed for the combined shroud and true position assurance comb, because the true position assurance is provided in part by the shroud, and in part by the position assurance comb.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/870,853 filed Aug. 28, 2013. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates generally to a connector having single insertion press-fit pins, where the connector is sealed, even when not connected to a corresponding connector or harness plug. 
       BACKGROUND OF THE INVENTION 
       [0003]    Various types of control units, such as transmission control units (TCU) or engine control units (ECU), which are stand-alone units, have connectors that are used to connect the TCU or ECU to other devices. In systems having a connector which is sealed when not mated to a corresponding electrical connector or harness plug, the pins are required to be sealed when the mating harness plug is not connected. Some designs use a purchased connector from a supplier, and the sealant is dispensed against the plastic connector surface to seal the pins. 
         [0004]    With some of these sealed connector designs, the stand-alone unit requires a small aperture in a heat sink or a cover, which is used to avoid a build-up of internal air pressure. A build-up of air pressure may damage the perimeter seal during the assembly process. The small aperture then must be sealed with another component such as a ball bearing or adhesive label. 
         [0005]    Traditionally, single insertion press fit pins are only used in unsealed applications, because these types of pins are difficult to seal. 
         [0006]    Accordingly, there exists a need for a sealed connector which uses single insertion press-fit pins, where the connector is sealed even when not connected to a corresponding connector or harness plug. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is a method of creating a sealed, un-mated electrical connector system using single insertion press-fit pins. By using single insertion press-fit pins, a connector supplier is no longer necessary to create the connector system. This allows for use of simple plastic parts for the connector shroud and a true position assurance comb in conjunction with single insertion press-fit pins. The result is a lower cost for the final connector assembly. Less plastic is needed for the combined shroud and true position assurance comb, because the true position assurance is provided in part by the shroud, and in part by the position assurance comb. 
         [0008]    In the present invention, the gaps between the press-fit pins and printed circuit board (PCB) allow for the flow of air through apertures formed as part of the PCB, which provides the proper venting of air, thereby preventing the buildup of internal air pressure during the assembly process. The apertures are then sealed with a sealant, eliminating the need for an additional sealing label. This allows for a true position assurance comb having an anti-scoop rib to be incorporated into the assembly, which is a benefit during manufacturing, such that the anti-scoop rib may be used during a pick and place operation. The insertion force on the pins (as the connector is connected to a corresponding connector) is distributed by the cured sealant, which is bonded to the aluminum heat sink in the pocket. The area of the pins exposed to the sealant is also an area of the pins which does not have the anti-tarnish material used on silver plated pins (the anti-tarnish material inhibits the ability for the sealant to cure). 
         [0009]    There are several steps used to assemble the connector of the present invention. A sub-assembly, or housing is created having a plastic shroud, which is attached to an aluminum heat sink, and an outer sealant is dispensed between them. A printed circuit board is then populated with single insertion press-fit pins. A thermally conductive adhesive is then applied to the sub-assembly, and the printed circuit board is connected to the sub-assembly. This creates a pocket for holding a low viscosity sealant. The low viscosity sealant is dispensed in the pocket, and a true position assurance comb is placed over the pins and onto the sealant. 
         [0010]    In one embodiment, the present invention is an electrical connector which includes a housing having a cavity, a shroud integrally formed as part of the housing, and a heat sink connected to the housing. A printed circuit board is connected to the heat sink, such that the heat sink is between the printed circuit board and the housing. At least one aperture is formed as part of the printed circuit board, and at least one pin is located in the aperture formed as part of the printed circuit board such that the at least one pin extends into the cavity of the housing. A pocket is formed by a central aperture in the heat sink, at least a portion of the printed circuit board, and part of a thermally conductive adhesive disposed between the printed circuit board and the heat sink. A sealant is located in the pocket such that at least part of the sealant contacts the printed circuit board and the thermally conductive adhesive, and also at least partially surrounds the pin. The sealant at least partially seals the area between the heat sink and the printed circuit board. 
         [0011]    At least one recess is formed as part of the housing, at least one rib is formed as part of the heat sink, and the rib is at least partially disposed in the recess when the heat sink is connected to the housing. An outer sealant is disposed in the recess such that the outer sealant at least partially surrounds the rib, and the outer sealant prevents debris from entering the housing. The heat sink may be connected to the housing in different ways. In one embodiment, the outer sealant is cured, and the curing process applied to the outer sealant provides a connection between the heat sink and the housing. 
         [0012]    In another embodiment, the electrical connector also includes at least one aperture formed as part of the housing, and at least one aperture is formed as part of the heat sink, such that the aperture formed as part of the heat sink is substantially aligned with the aperture formed as part of the housing. A fastener is inserted through the aperture formed as part of the heat sink and into the aperture formed as part of the housing to connect the heat sink to the housing. 
         [0013]    A position assurance comb is disposed in the pocket such that at least a portion of the sealant is disposed between the position assurance comb and the printed circuit board. An anti-scoop rib is formed as part of the position assurance comb, which provides proper alignment of the pin during the connection of the at least one pin to another connector. 
         [0014]    As mentioned above, the thermally conductive adhesive is disposed between the printed circuit board and the heat sink, such that the thermally conductive adhesive connects the printed circuit board and the heat sink. A portion of the sealant located in the pocket is in contact with the thermally conductive adhesive, such that the thermally conductive adhesive at least partially contains the sealant in the pocket. 
         [0015]    The pin is mounted in the aperture formed as part of the printed circuit board though the use of a press-fit connection, or the like, and at least a portion of the sealant is located in the aperture such that the sealant at least partially surrounds the pin. 
         [0016]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0018]      FIG. 1  is an exploded view of an electrical connection system, according to embodiments of the present invention; 
           [0019]      FIG. 2  is a sectional side view of an electrical connection system, according to embodiments of the present invention; 
           [0020]      FIG. 3  is a sectional side view of a sub-assembly used as part of an electrical connection system, according to embodiments of the present invention; 
           [0021]      FIG. 4  is a sectional side view of a printed circuit board having single insertion press-fit pins, which is used as part of an electrical connection system, according to embodiments of the present invention; 
           [0022]      FIG. 5  is a sectional side view of an electrical connection system, prior to assembly of the position assurance comb, according to embodiments of the present invention; and 
           [0023]      FIG. 6  is an exploded view of an alternate embodiment of an electrical connection system, according to embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0025]    A connector having a connection system according to the present invention is shown in  FIGS. 1-2  generally at  10 . The connector  10  includes a housing  12  having a connector shroud  14 . In one embodiment, there are apertures  16  formed as part of the housing  12  which are used for receiving corresponding fasteners, which in this embodiment are screws  18 . The screws  18  also extend through apertures  20  which are formed as part of a heat sink  22 , such that the screws  18  connect the heat sink  22  to the housing  12 . 
         [0026]    The heat sink  22  includes ribs  24  which partially extend into recesses  26  formed as part of the housing  12 . Also located in the recesses  26  is a first sealant, or an outer sealant  28 , which is used for preventing debris and moisture from entering the housing  12 . In one embodiment, the heat sink  22  and the housing  12  are clamped together after the outer sealant  28  is placed in the recess  26 , and the sealant  28  is cured, such that once the curing process is complete, the sealant  28  connects the housing  12  to the heat sink  22 . 
         [0027]    During assembly, the housing  12  may be attached to the heat sink  22  using the screws  18 , as mentioned above, to hold the heat sink  22  and the housing  12  in place while the outer sealant  28  cures, or the heat sink  22  and housing  12  may be clamped together and held in place while the outer sealant  28  cures. Either approach may be used during assembly, and still be within the scope of the invention. 
         [0028]    The connector  10  also has a printed circuit board (PCB)  30 , which is attached to the heat sink  22  with a thermally conductive adhesive  32 . The PCB  30  may also be attached to the heat sink  22  using a thermal interface material, or a pressure sensitive adhesive, and is not limited to use with the thermally conductive adhesive  32 . 
         [0029]    The PCB  30  also has a first set of apertures  34 , which in this embodiment are outer apertures  34 , through which the screws  18  extend, allowing the screws  18  to be exposed so a screwdriver or the like may be used to rotate the screws  18  during assembly. The PCB  30  also includes a second set of apertures  36 , or inner apertures  36 , and a pin  38  extends through each aperture  36 . The pins  38  are press-fit into each of the inner apertures  36 , and therefore there is no need for an additional adhesive to hold the pins  38  in place. 
         [0030]    The heat sink  22  also includes a central aperture  40 , and each of the pins  38  extends through the central aperture  40  and into a cavity, shown generally at  42 , formed as part of the housing  12 . The cavity  42  has multiple inner diameters, and one of the inner diameters  44  is substantially similar to the diameter of the central aperture  40 . The central aperture  40  and the top surface  46  of the PCB  30  form part of a pocket, shown generally at  48 . The pocket  48  also includes the areas between the PCB  30  and the heat sink  22  which are next to the thermally conductive adhesive  32 . Disposed within the pocket  48  is a second sealant, or inner sealant  50 , which substantially surrounds the pins  38 , and holds the pins  38  in place once the sealant  50  is cured. The sealant  50  is also partially disposed between the heat sink  22  and the PCB  30 , in an area adjacent the thermally conductive adhesive  32 . The sealant  50  is a low viscosity fluid, and has a low enough viscosity that the sealant  50  only partially flows into the apertures  36  that the pins  38  are disposed in, but the sealant  50  does not flow through the apertures  36  enough to drain the pocket  48 . Also disposed in the pocket  48  is a position assurance comb, shown generally at  52 , having an anti-scoop rib  54 . 
         [0031]    After the sealant  50  is placed in the pocket  48 , the comb  52  is placed in the pocket  48  such that the comb  52  is on top of the sealant  50 , and is also held in place by the sealant  50  once the sealant  50  is cured. The comb  52  also has several apertures  56 , and each pin  38  extends through a corresponding aperture  56 . The anti-scoop rib  54  functions to correctly position a corresponding connector to align with the pins  38  of the connector  10 , preventing pins  38  from scooping, or deflecting and permanently deforming. The sealant  50  also functions to absorb some of the insertion force applied to the pins  38  when the connector  10  is attached to a corresponding connector. 
         [0032]    Referring to  FIG. 1 , there is also a third sealant, or lower sealant  58  disposed in a groove  60  formed as part of the heat sink  22 . The third sealant  58  is used to connect a cover  62  to the heat sink  22 . More specifically, the sealant  58  is placed into the groove  60 , and then the cover  62  is correctly positioned relative to the heat sink  22 , and then exposed to a curing process. Once the curing process is complete, the sealant  58  provides a connection between the heat sink  22  and the cover  62 . There is also a label  64  attached to the cover  62 , which may be used to identify the connector, by a serial number or the like. 
         [0033]    A method of assembling a connector  10  according to the present invention is shown in  FIGS. 3-5 . In  FIG. 3  the housing  12  is created having the connector shroud  14  and connected to the heat sink  22  using the screws  18  or a clamping process, as described above, and the sealant  28  is dispensed between them. The single insertion pins  38  are then press-fitted into the apertures  36  of the PCB  30 , as shown in  FIG. 4 . The thermal conductive adhesive  32  is applied to the heat sink  22 , and the PCB  30  is bonded to the heat sink  22  using the adhesive  32 . This creates part of the pocket  48  for holding the low viscosity sealant  50 , as shown in  FIG. 5 . As the sealant  50  enters the pocket  48 , the apertures  36  allow for air to escape the pocket  48 , preventing the build-up of internal air in the pocket  48  during the assembly process. 
         [0034]    After the low viscosity sealant  50  is dispensed in the pocket  48 , the position assurance comb  56  is placed over the pins  38  and onto the sealant  50 , as shown in  FIG. 2 . Once the entire connector  10  is assembled as shown in  FIG. 2 , the connector  10  is exposed to an environment to cure the sealants  28 , 50 , 58 , such that the outer sealant  28  is cured and connects the heat sink  22  and the housing  12 , the lower sealant  58  is cured and connects the cover  62  to the heat sink  22 , and the inner sealant  50  is cured and secures the location of the pins  38  in the pocket  48 , and secures the position assurance comb  52  in the pocket  48  as well. 
         [0035]    The anti-scoop rib  54  is able to be gripped during the assembly process, such as during a “pick and place” operation, where the rib  54  is gripped and used to assemble the comb  52  in the housing  12 . 
         [0036]    An alternate embodiment of the present invention is shown in  FIG. 6 , with like numbers referring to like elements. However, in this embodiment, the PCB  30 , the thermally conductive adhesive  32 , and the cover  62  are shaped differently. These components have a trapezoidal shape, as opposed to being substantially rectangular, as shown in  FIG. 1 . Additionally, instead of inserting the screws  18  through the apertures  34  in the PCB  30 , and then through the apertures  20  of the heat sink  22  and into the apertures  16  of the housing  12 , as shown in  FIG. 2 , the screws  18  in  FIG. 6  are inserted through the apertures  66  (where the apertures  66  and screws  18  in  FIG. 6  are formed differently from the apertures  16  and screws  18  shown in  FIG. 1 ) first, then the screws  18  are inserted into apertures (not shown) formed as part of posts  68 , where the posts  68  are formed as part of the heat sink  22 . The screws  18  secure the heat sink  22  and the housing  12  together prior to the sealant  28  being cured. 
         [0037]    As mentioned above, the apertures  66  are shaped differently from the apertures  16  shown in  FIG. 1 . The apertures  16  in  FIG. 1  do not extend through the housing  12 , and therefore, when the screw  18  is inserted into the apertures  16 , the housing  12  is sealed from the outside environment. The apertures  66  in  FIG. 6  extend through the housing  12 , and the screws  18  in  FIG. 6  have a large diameter head  70  which contacts the area surrounding the aperture  66 , to prevent debris from entering the area between the housing  12  and the heat sink  22 . 
         [0038]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.