Abstract:
An overmolded electronic device includes a pre-mold assembly having a positioning pin that extends upward through a mold material into contact with an inner cavity of a mold. The positioning pin is disposed within a containment area that is defined by sets of ribs configured in and conformed on the pre-mold assembly. The positioning pin thereby is sealed within the containment area that is in turn sealed from the remainder of the electronic device that prevents the intrusion of moisture or other contaminants into undesirable locations of the electronic device.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention generally relates to features for controlling contaminant intrusion into an overmolded product. 
         [0002]    Electronics and other sensitive devices that are utilized in exposed environments are typically overmolded with plastic or other settable materials to protect against moisture and other contaminants that could possibly cause damage. The protective overmold is formed by first inserting and positioning the devices within a mold cavity, and filling that cavity with molten plastic around the device. The device is held in place during the overmolding operations to prevent undesirable shifting caused by the pressures experienced during injection of plastic into the cavity. Conventional overmolded devices will include a positioning pin that contacts the surface of the mold cavity to maintain a desired position of the device during the molding process. The positioning pin is often part of a pre-mold formed over a portion of the electronic device. 
         [0003]    Disadvantageously, the positioning pin necessarily extends through the overmold creating a seam between the positioning pin and overmold that creates a path that could allow intrusion of moisture or other contaminants. It is known to create tortuous paths through complex shaped positioning pins. However, such shapes increase cost and restrict the placement of the positioning pin. 
         [0004]    Accordingly, it is desirable to design and develop a device and process for holding an overmolded item in place that effectively seals any potential leak paths and provides greater placement options. 
       SUMMARY OF THE INVENTION 
       [0005]    An example pre-mold assembly for an overmold includes a positioning pin for aligning the pre-mold assembly within a mold. The pre-mold includes a first set of ribs and a second set of ribs on opposing sides of the positioning pin to prevent contaminant intrusion. 
         [0006]    The example pre-mold assembly includes a positioning pin that extends through an overmold material into contact with a portion of a mold to align the pre-mold as desired. The pre-mold includes first and second sets of ribs disposed on opposite sides of the pin. The ribs are not part of the pin but instead part of the pre-mold and positioned on either side of the positioning pin to prevent intrusion of contaminants that may penetrate through the interface of the positioning pin and the overmold material. 
         [0007]    The ribs define a tortuous path that substantially prevents contaminants from passing the ribs. Further, the ribs may also form a material that melts in response to the overmolded material during injection. The ribs may melt and then intermingle with the overmolded product creating a barrier to moisture or other contaminants that may intrude and leak through the interface between the overmolded product and the pre-mold in the vicinity of the positioning pin. 
         [0008]    Accordingly, the pre-mold assembly according to this invention provides for the positioning of a pre-mold assembly within a mold cavity while also providing for the isolation and prevention of contaminants from intruding into protected areas of a device. 
         [0009]    These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a cross-sectional view of an example overmolded assembly according to this invention. 
           [0011]      FIG. 2  is a perspective view of a pre-mold assembly according to this invention. 
           [0012]      FIG. 3  is a perspective view of another example pre-mold assembly according to this invention. 
           [0013]      FIG. 4  is a perspective view of another example pre-mold according to this invention. 
           [0014]      FIG. 5  is a cross-sectional view of another example pre-mold assembly according to this invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0015]    Referring to  FIG. 1 , an overmold assembly  10  includes a pre-mold  12 . The pre-mold  12  includes positioning pins  14  that extend through overmold material  24 . The positioning pins  14  are provided to abut a mold surface  28  to position the pre-mold assembly  12  within a mold  26 . The example pre-mold assembly  12  protects the electric conductors  18  from damage during handling prior to molding and also provides alignment within the mold  26 . The pre-mold assembly  12  provides the initial encasing and protecting of electrical components such as the example electrical conductors  18 , and also can be utilized to protect other electrical devices such as printed circuit boards, specialized intergraded circuits, capacitors, inductors or any other electrical or magnetic device. The pre-mold assembly  12  includes the positioning pins  14  that provide for the accurate positioning of the conductors  18  within the final overmold material  24 . 
         [0016]    The pre-mold assembly  12  includes first and second sets of ribs  16 . The ribs  16  define a containment area  20 . The confinement area  20  traps any moisture or contaminants upon entry through any seam  25  between the positioning pins  14  and the overmold material  24 . Contaminants or moisture is contained within the containment area  20  disposed between the ribs  16 . In this way the pins  14  are configured as a simple cylinder or other shape that is conducive to the positioning of the overmold assembly  12  within the mold  26 . This eliminates the need for complex designs and shapes of the positioning pin thereby simplifying the design of the positioning pin  14 . 
         [0017]    Referring to  FIG. 2 , a perspective view of the pre-mold assembly  12  is illustrated without the overmolding material. The positioning pin  14  is exposed and extends outwardly from a body  22  of the pre-mold assembly  12  to abut the mold tool inner surface  28  ( FIG. 1 ) and align the electrical conductors  18  within the mold  26  ( FIG. 1 ). The positioning pin  14  is disposed between rib sets  16  such that the positioning pin  14  is within the containment area  20 . The containment area  20  limits the area within the encapsulated assembly that is potentially exposed to moisture through the seam  25  ( FIG. 1 ) between the positioning pin  14  and the overmold material  24 . 
         [0018]    Referring to  FIG. 3 , another pre-mold assembly  15  includes two positioning pins  14  extending from a first side within the containment area  20 . As appreciated, many example positioning pins  14  can be disposed within the containment area  20  and substantially sealed off from electrical conductors and other sensitive areas with only a few sets of ribs  16 . In this way, the pre-mold assembly  15  can be rigidly held in a desired location and still provide desired protection from intrusion of moisture or other contaminants. 
         [0019]    Referring to  FIG. 4 , another pre-mold assembly  30  is illustrated and includes electrical conductors  18  that extend there through. A third leg  34  extends transverse to other portions of the pre-mold body. The third leg  34  includes a third set of ribs  32  that combines with the first and second sets of ribs  16  to define an enlarged containment area  21 . The containment area  21  then can include the pins  14  to provide for the proper alignment of the pre-mold assembly  30 . 
         [0020]    The example pre-mold assembly  30  illustrates the use of multiple positioning pins  14  with a few or reduced number of sealed ribs  16 . Many positioning pins  14  can be provided within the containment area defined by the ribs  16  and  32 . The ribs  16  and  32  combine to provide the geometry desired to contain exposure to any seam between the positioning pins  14  and the overmold. 
         [0021]    Referring to  FIG. 5 , an example electronic device assembly  40  is illustrated and includes a Hall Effect sensor  42 . As appreciated, the Hall Effect sensor  42  is an electronic device that is desired to be protected from the intrusion of moisture. Although the illustrated example electronic device include a Hall Effect sensor other electronic devices are also within the contemplation of this invention such as a printed circuit board, Hall Effect IC, or a MR IC. 
         [0022]    The pre-mold assembly  46  of this invention includes positioning pins  52  that space and align the Hall Effect sensor  42  within a mold cavity. The pre-mold  46  is then overmolded with an overmold material  44 . Between the overmold material  44  and the pre-mold  46  a space or path is defined. The pre-mold assembly  46  includes two sets of ribs  50 . These ribs  50  create a torturous path that prevents the intrusion of moisture or other contaminants into or to the Hall Effect sensor  42  or other electronic devices that are overmolded. The ribs  50  define a containment area within which the positioning pins  52  are disposed. Any number of positioning pins  52  may be disposed within this containment area that is defined by these ribs  50 . 
         [0023]    The ribs  50  prevent the intrusion of moisture or other contaminants into undesired areas of the electronic device by defining a torturous path that substantially prevents the intrusion of moisture. The ribs  50  may also be formed or a material that melts in response to the pressures and heat of the overmolding material. In such an instance, the melt ribs will be of such a thickness and/or shape as to melt and intermingle with the overmolded material. While other portions of the pre-mold  46  that are of thicker material will not melt to the same extent as the thinner ribs  50 . Thereby, the ribs  50  will melt and intermingle with the overmolding creating a bond which forms a barrier to moisture and other contaminants into the undesired locations of the overmolded electronic device  40 . 
         [0024]    Accordingly, the pre-mold assembly provides for the containment of moisture or other contaminants that could intrude between a pre-mold and an overmold assembly at or in the proximity of positioning pins. Further, the pre-mold assembly includes sets of ribs that define a containment area within which any number of positioning pins may be disposed. 
         [0025]    Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.