Abstract:
A vehicle power distribution circuit board has interconnected electronic components and a connector mounted thereon. The interconnected electronic components include one or more heat generating components. The connector includes a main body formed of an electrically insulating material for supporting a plurality of terminals. The terminals have first ends connected to the circuit board and second ends adapted to be connected to a mating connector of a vehicle wiring harness. The main body of the connector is configured to form an air gap between the main body and the circuit board, and the terminals extend from the main body to the first end through the gap. Also, the connector is positioned on the circuit board with a thermally conductive path from one of the heat generating components to the gap such that the terminals within the air gap function as a heat sink to dissipate heat from the heat generating component.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part patent application of U.S. patent application Ser. No. 12/006,973, filed Jan. 7, 2008, the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention relates in general to printed circuit boards (PCBs). In particular, this invention relates to an improved heat sink for removing excess heat produced by electronic components on a PCB. 
         [0003]    As the use of electronic devices becomes increasingly prevalent, there is a desire to provide an increasing number of electronic components on PCBs. In many applications, electrical connections on PCBs are being made with surface mount technology (SMT). With SMT components, blade terminals are connected to a surface on one side of the PCB, usually by soldering. This leaves the opposite side of the PCB available for constructing a different circuit using SMT components. This allows a greater number of circuits to be installed on a single PCB. 
         [0004]    The electronic components mounted on a PCB can generate heat as they operate. This heat will raise the temperature of the PCB and attached components. The PCB can be damaged if the temperature becomes high enough. Therefore, it is desirable to remove excess heat from a PCB. Heat can often be removed from a PCB using a heat sink. A typical heat sink is made of a thermally conductive material and has a base in contact with a hot component. The heat sink has several fins that increase the surface area of the sink and allow it to transfer heat into the surrounding air. 
         [0005]    With an increasing number of electronic components being mounted on a PCB, there is the potential for an increasing amount of heat to be created. Also, putting additional components on a PCB reduces the amount of space available for the attachment of heat sinks. It would be desirable to provide an improved mechanism for removing excess heat from a PCB. 
       SUMMARY OF THE INVENTION 
       [0006]    This invention relates to a vehicle power distribution circuit board. The circuit board has interconnected electronic components and a connector mounted thereon. The interconnected electronic components include one or more heat generating components. The connector includes a main body formed of an electrically insulating material for supporting a plurality of terminals. The terminals have first ends connected to the circuit board and have second ends adapted to be connected to a mating connector of a vehicle wiring harness. The main body of the connector is configured to form an air gap between the main body and the circuit board, and the terminals extend from the main body to the first ends through the gap. Also, the connector is positioned on the circuit board with a thermally conductive path from one of the heat generating components to the gap such that the terminals within the air gap function as a heat sink to dissipate heat from the one power component. 
         [0007]    Various aspects of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a perspective view of a first embodiment of a modular electrical connector. 
           [0009]      FIG. 2A  is a top plan view of an electrical box for a vehicle that includes a first printed circuit board and the modular electrical connector illustrated in  FIG. 1   
           [0010]      FIG. 2B  is a perspective view of an in-line connector structured and configured to mate with the modular electrical connector illustrated in  FIG. 1 . 
           [0011]      FIG. 3  is an enlarged perspective view of a body portion of the modular electrical connector illustrated in  FIG. 1 . 
           [0012]      FIG. 4  is an exploded perspective view of the modular electrical connector illustrated in  FIG. 1 . 
           [0013]      FIG. 5  is a perspective view of a second printed circuit board including multiple electrical connectors. 
           [0014]      FIG. 6  is a cross sectional view taken through line  6 - 6  of  FIG. 5 . 
           [0015]      FIG. 7  is a cross sectional view taken through line  7 - 7  of  FIG. 6 . 
           [0016]      FIG. 8  is a cross sectional view, similar to that shown in  FIG. 7 , of an electrical connector with a first alternative terminal design, in which the terminals are located within a gap. 
           [0017]      FIG. 9  is a cross sectional view, similar to that shown in  FIGS. 7 and 8 , of an electrical connector with a second alternative terminal design, in which the terminals extend outside the gap. 
           [0018]      FIG. 10  is a cross sectional view, similar to that shown in  FIGS. 7 ,  8 , and  9 , of an electrical connector with a third alternative terminal design, in which the terminals do not cross each other and extend outside the gap. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    Referring now to the drawings, there is illustrated in  FIG. 1  a first embodiment of a surface mount technology (SMT) modular electrical connector, indicated generally at  10 . The illustrated electrical connector  10  is a header connector that can be used in an electrical box such as may be used in a vehicle, such as the electrical box  12  shown in  FIG. 2A . The electrical box  12  may, for example, be a power distribution box, a junction box, and the like. As shown in  FIG. 2A , the electrical box  12  includes a plurality of electronic components  14 A,  14 B,  14 C,  14 D, and  14 E, which are attached to a PCB  16 . If, for example, the electrical box  12  is a power distribution box in a vehicle, an in-line connector  18 , as shown in  FIG. 2B , may be used to connect the electrical connector  10  to various systems within the vehicle via a wiring harness  20 . 
         [0020]    Referring to  FIGS. 1 and 4 , the electrical connector  10  includes a body  22  and a plurality of electrical terminals  24  and  26 . The body  22  includes one or more body portions  28  having an axis A, an upper or first surface  30 , a lower or second surface  32 , a first mating surface  34 , and second mating surface  36 . The illustrated electrical connector  10  includes three identical body portions  28 , but the electrical connector may include a different number of body portions and may include different types of body portions. An axially extending mounting aperture  38  is formed between the mating surface  34  and the mating surface  36 . 
         [0021]    As best shown in  FIG. 3 , four terminals  24  are integrally formed with each illustrated body portion  28 . Each terminal  24  is substantially L-shaped and has a blade end  40  (extending upwardly from the body portion  28  when viewing  FIG. 3 ) and an SMT end  42  (extending downwardly from the body portion  28  when viewing  FIG. 3 ) having a solder aperture  44 . 
         [0022]    The SMT end  42  of the terminals  24  may be connected to a PCB  16  by any SMT connection methods that are familiar to those skilled in the art, such as the method described in U.S. patent application Ser. No. 11/624,409. The method of connecting an SMT terminal end disclosed therein is incorporated herein by reference. 
         [0023]    The body portions  28  may be formed from plastic such as polyamide (PA), polyphthalamide (PPA), or other desired thermoplastic material. The body portions  28  may also be formed of thermally conductive material, such as ceramic and polymer filled with heat conductive fibers and/or fillers. Thermally conductive body portions  28  will create an equalization block, enhance heat transfer between terminal blade ends  40 , and improve PCB heat dissipation performance. It will be understood that some body portions, such as the body portions  28 , may be made of high temperature capable polymers, and that other body portions may be made of relatively lower performance or relatively lower temperature capable polymers. 
         [0024]    In the illustrated embodiment, the blade ends  40  are 2.8 mm blade terminals. Alternatively, the blade ends  40  may be any other desired type of terminal, such as 0.64 mm, 1.2 mm, 1.5 mm, 4.8 mm, and 6.3 mm blade terminals. 
         [0025]    The body  22  also includes a first end portion  46  and a second end portion  48 . The first end portion  46  has an upper or first surface  50 , a lower or second surface  52 , an end surface  54 , and the second mating surface  36 . An axially extending mounting aperture  56  is formed between the end surface  54  and the second mating surface  36 . The second end portion  48  is substantially similar to the end portion  46  and has an upper or first surface  50 , a lower or second surface  52 , an end surface  58 , and the first mating surface  34 . An axially extending mounting aperture  60  is formed between the end surface  58  and the first mating surface  34 . 
         [0026]    In the illustrated embodiment, one of the terminals  26  is integrally formed with each of the end portions  46  and  48 . Each terminal  26  has a blade end  62  (extending upwardly from the end portion  46  as shown in  FIG. 4 ) and an eye-of-the-needle terminal end  64  (extending downwardly from the end portion  46  as shown in  FIG. 4 ). Such eye-of-the-needle terminal ends  64  attach the connector body  22  to the PCB  16  and ensure that the body  22  remains attached to the PCB  16  during the soldering of the SMT ends  42  of the terminal  24 . 
         [0027]    Alternatively, the terminals  24  and  26  may be “stitched in” to the body portions  28  and the end portions  46  and  48 , respectively, in an automated manufacturing operation that is familiar to those skilled in the art. 
         [0028]    The end portions  46  and  48  may be formed from plastic, such as for example; polyamide (PA), polyphthalamide (PPA), or other desired thermoplastic material. The end portions  46 ,  48  may be formed of thermally conductive material, such as ceramic, and polymer filled with conductive fibers and/or fillers to create equalization block, enhance heat transfer between terminal blade ends  62 , and improve PCB heat dissipation performance. It will be understood that some end portions, such as the end portions  46 ,  48  may be made of high temperature capable polymers, and that other body portions may be made of relatively lower performance or relatively lower temperature capable polymers. In the illustrated embodiment, the blade end  62  is a 6.3 mm blade terminal. Alternatively, the blade end  62  may be any other desired type and size of terminal, such as 9.5 mm blade terminal. 
         [0029]    As best shown in  FIGS. 1 and 4 , the electrical connector  10  may be described as modular, that is, the electrical connector  10  may be created by assembling selected component parts. For example, the electrical connector  10  may be built by providing the connecting rod  66  and assembling any desired number of body portions  28  on the connecting rod  66  between the first end portion  46  and the second end portion. The connecting rod  66  will extend through the mounting apertures  38 ,  56 ,  60 , such that a portion of the rod  66  extends outwardly beyond the end surfaces  54  and  58 . The ends of the rod  66  may then be deformed, as shown at  68  in  FIG. 1 , by any desired method, such as by heat staking or by sonic welding. The illustrated rod  66  has a rectangular cross section to prevent rotation and/or axial bending of the assembled components prior to heat staking or sonic welding. Alternatively, the rod  66  may have any other desired cross sectional shape, such as square, triangular, other geometric shapes, and oval and irregular shapes. 
         [0030]    In the illustrated embodiment, the mating surfaces  34  and  36  are stepped. It will be understood however, that the mating surfaces  34  and  36  may have any desired shape which facilitates the interconnection of the mating surfaces  34  and  36 . 
         [0031]    In the embodiment illustrated in  FIG. 1 , the electrical connector  10  includes three body portions  28 . It will be understood however, that the electrical connector  10  may be formed with any desired number of body portions, such as one body portion  28 , two body portions  28 , or four or more body portions  28 . 
         [0032]    The small size of the body portion  28  and end portions  46 ,  48  relative to known SMT connector strips minimizes the effect of material shrinkage and warping that can occur when molding or forming larger connector strips or components. Accordingly, lower cost polymers may be used. Additionally, the final assembly process of the electrical connector  10  allows for adjustment and alignment of the component body portions  28  and end portions  46 ,  48 , such that required tolerances may be easily achieved. 
         [0033]    By standardizing the size and geometry of the internal components (i.e., the terminals  24 ) and external components (i.e., the body portions  28 ), a common mold tool may be used, reducing cost. Additionally, automated assembly equipment may be used for final electrical connector  10  assembly. 
         [0034]    The electrical connector  10  described herein above is modular and scalable to allow the manufacture of multiple different PCB header connectors, such as the electrical connector  10 , using different combinations of the body portions  28 , end portions  46 ,  48 , and rods  66 , and processes, such as heat staking or sonic welding. 
         [0035]    It will be understood that the body portions  28  and end portions  46  and  48  may have any desired number and combination of electrical terminals, such as the terminals  24  and  26 . For example, one body portion  28  may have a first combination of electrical terminals  24 , an adjacent body portion  28  may have a second combination of electrical terminals  24 , and the end portions  46  and  48  may have a third combination of electrical terminals  26 , advantageously allowing for modularity and scalability to allow the manufacture of multiple different PCB header connectors. 
         [0036]    Reduced overall complexity of the component parts of the electrical connector  10  allows for efficient use of manufacturing equipment. For example, one family mold (i.e., a single molding tool with multiple cavities for all assembly components) may be used to form the body portions  28 , end portions  46 ,  48 , and rod  66 . A single assembly machine may be used to stitch terminals  24  into the body portions  28 , end portions  46 ,  48  (if the terminals  24  are not integrally molded therewith). 
         [0037]    Referring now to  FIG. 5 , there is shown a perspective view of a second PCB  116 . The second PCB  116  is a power distribution circuit board, but may be any other type of circuit board. The second PCB  116  includes a plurality of electronic components  114 . The electronic components  114  may include switches, resistors, capacitors, solid state components, or any other type of electronic component. The electronic components  114  are attached by surface mounting, but may be attached in other ways. The second PCB  116  also includes multiple electrical connectors  110 . The electrical connectors  110  have different configurations of electrical terminals  124  and  126 . 
         [0038]    The second PCB  116  also includes a series of traces  115 . The traces are electrically conductive pathways that serve to connect the electrical connectors  110  and the electronic components  114 . The traces  115  are made of a suitable electrically conductive material, such as copper. However, other desired materials may be used. It should be appreciated that the configuration of electronic components  114 , electrical connectors  110 , and traces  115  shown in  FIG. 5  is for descriptive purposes only and is not intended to depict an actual circuit layout. 
         [0039]    The electrical connectors  110  are connected to in-line connectors  118  and wiring harness  120 . Only one in-line connector  118  and one wiring harness  120  are shown in  FIG. 5  for clarity. The wiring harnesses  120  allow the second PCB  116  to connect to various systems (not shown) located remotely from on the second PCB  116 . 
         [0040]    Referring now to  FIGS. 6 and 7 , cross sectional views of a portion of the second PCB  116  are shown. The cross section shown in  FIG. 6  is taken along line  6 - 6  of  FIG. 5  and is taken through one of the electrical connectors  110 . The cross section shown in  FIG. 7  is taken along line  7 - 7  of  FIG. 6 . As shown, the electrical connector  110  includes a body  122  and a plurality of electrical terminals  124  and  126 . It should be appreciated that the electrical connector  110  may be a modular electrical connector, as described in reference to  FIGS. 1 through 6 , but that this is not necessary, and the electrical connector  116  may be a non-modular design, if desired. The body portion  122  may be formed from plastic, such as for example, polyamide (PA), polyphthalamide (PPA), or other desired material. The body  122  may be formed of thermally conductive material, such as ceramic and polymer filled with heat conductive fibers and/or fillers. 
         [0041]    The surface mounted ends of terminal  124  are connected to the second PCB  116  by the method described in U.S. Pat. No. 7,458,828, though they may be connected by any desired methods. Each terminal  126  has a blade end  162  and an eye-of-the-needle terminal end  164 . Such eye-of-the-needle terminal ends  164  attach the connector body  122  to the second PCB  116  and help the body  122  remain attached to the second PCB  116  during the soldering of SMT ends  142  of the terminals  124 . As described in U.S. Pat. No. 7,458,828, a solder aperture on the SMT end  142  of the terminal  124  assists in obtaining a good electrical connection between the terminal  124  and the second PCB  116 . By obtaining a good electrical connection between these components, there is less resistance to electrical conductivity and less waste heat is generated at these connections. It should also be appreciated that a good electrical connection between the terminal  124  and the second PCB  116  also provides improved thermal conductivity between the terminal  124  and the second PCB  116 . 
         [0042]    The electrical connector  110  includes an optional space or gap  133  between a lower surface  132  of the body  122  and the second PCB  116 . The body  122  is situated a distance or height  135  from the second PCB  116 . The height  135  may be any desired size. The gap  133  allows air to circulate past the SMT ends  142  of the terminals  124 . This air circulation allows an increased amount of heat to be removed by convection. As shown, the L-shaped terminals  124  are situated so that they pass through the gap  133 . It should be appreciated that the L-shaped configuration of the terminals  124  increases the surface area of the terminals  124  that is exposed within the gap  133 . That is, the terminal  124  travels from the lower surface  132  of the body  122  to the second PCB  116  along a path that is greater than the height  135  of the gap  133 . This increased length of the terminals  124  further increases the amount of heat that can be removed from the terminals  124  by convection. 
         [0043]    The gap  133  facilitates natural convection, as heated air is able to flow away from the terminals  124 . It should be appreciated that a fan or blower (not shown) could be included to provide for forced convection in order to further assist with removal of excess heat from the connector  110 . 
         [0044]    By making the body portion  122  of the electrical connector  110  of thermally conductive material, the electrical connector  110  has an increased heat capacity. That is, the electrical connector  110  is able to store a greater amount of heat than it would be if it were made of material that is not thermally conductive. Also, the electrical connector  110  provides an equalization block. That is, heat is able to transfer along its length. Thus, if a first end portion  146  is at a higher temperature than a second end portion  145 , the excess heat is able to conduct along the thermally conductive portions of the electrical connector  110 . 
         [0045]    The in-line connector  118  (shown in  FIG. 5 ) is also formed of thermally conductive material, such as ceramic and polymer filled with heat conductive fibers and/or fillers. Therefore, the in-line connector  118  also acts as part of the equalization block, along with the electrical connector  110 . 
         [0046]    It should be appreciated that the described features of the electrical connector  110  make it suitable for use as a heat sink for the second PCB  116 . That is, the electrical connector  110  is able to remove excess heat generated by the electric component  114 . The gap  133  and the arrangement of the terminals  124  allows convection to remove excess heat. Additionally, heat in the electrical connector  110  will be conducted away through the heat conductive wiring in the attached wiring harness  120 . It should be appreciated that the electrically conductive wiring in the wiring harness  120  will transfer excess heat away from the electrical connector  110 . However, it should also be appreciated that additional heat conductive elements may be included in the wiring harness  120 , if desired. By making the electrical connector  110  of a thermally conductive material, excess heat at any hot spots on the electrical connector  110  is able to transfer to cooler parts of the electrical connector  110  and into the attached wiring harness  120 . 
         [0047]    By using the electrical connectors  110  as heat sinks for the electrical components  114 , the number of traditional heat sinks required to maintain the second PCB  116  at a desired temperature can be reduced. This allows the circuit board to be smaller than it otherwise would be because less surface area is occupied by the traditional heat sinks. 
         [0048]    Referring back to  FIG. 5 , it can be seen that the electric components  114  are mounted on the second PCB  116  at various distances from the various electrical connectors  110 . By reducing the distance separating the electric components  114  and the electrical connectors  110 , the amount of heat transferred from a given electrical component to an electrical connector can be increased. The electrically conductive traces  115  are also thermally conductive, allowing heat from the electric components  114  to transfer away from the relatively hot electric component  114  and to the relatively cool electrical connector  110 . It should be appreciated that additional thermally conductive material (not shown) may be included to facilitate this heat transfer. Because the electric components  114  are mounted in closer proximity to the electric connectors  110 , the size of the circuit board may be reduced because the density of elements on the circuit board is increased. 
         [0049]    The previous description has described the electrical components  114  and the electrical connectors as being on one side of the second PCB  116 . This side is the A-side of the second PCB  116 . In further reference to  FIGS. 6 and 7 , an electric component  114   a  is shown mounted on a B-side  117  of the second PCB  116 . It should be appreciated that the B-side  117  refers to the opposite side of the second PCB  116  from the A-side. The B-side  117  is an arbitrary designation, and the B-side  117  is physically no different from the A-side of the second PCB  116 . The B-side  117  of the second PCB may include additional electric components, traces, and electrical connectors (not shown). It should be appreciated that the electric component  114   a  will transfer heat through a substrate  119  of the second PCB  116  to the electrical connector  110 . The electrical connector  110  will then act as a heat sink for the electric component  114   a . Additionally, vias (not shown) may be provided through the substrate  119  of the second PCB  116  connecting the electrical connector  110  and the electric component  114   a . The vias are electrically conductive pathways that may be used to transfer electric power from the electrical connector  110  on the A-side of the PCB to the electric component  114   a  on the B-side  117  of the PCB. The vias may simultaneously assisting in the transfer of excess heat from the electric component  114   a  to the electrical connector  110 . Although the illustrated embodiment has described using the electrical connector  110  on the A-side as a heat sink, it should be appreciated that electrical connectors (not shown) on the B-side  117  of the second PCB  116  may also be used as heat sinks for the electric components  114  and  114   a.    
         [0050]    Referring to  FIGS. 8 through 10 , schematic views are shown illustrating various ways that an electrical connector may be attached to a circuit board.  FIG. 8  illustrates a PCB  216  including an electrical connector  210 . The electrical connector  210  includes terminals  224 . The terminals  224  extend through a gap  233 . The electrical connector  210  has a body portion  222  with a width D 1 . The terminals  224  are attached to the PCB  216  at contact points  244 . The contact points  244  on opposite sides of the electrical connector  210  are laterally spaced from each other by a distance D 2 . The distance D 2  is less than the width D 1  and the terminals  224  are located entirely within the gap  233 . 
         [0051]      FIG. 9  illustrates a PCB  316  including an electrical connector  310 . The electrical connector  310  has a body portion  322  with a width D 1 . Terminals  324  extend through a gap  333  and are attached to the PCB  316  at contact points  344 . The contact points  344  on opposite sides of the electrical connector  310  are laterally spaced from each other by a distance D 2 . The distance D 2  is greater than the width D 1  and the terminals  324  extend laterally outside of the gap  333 . 
         [0052]      FIG. 10  illustrates a PCB  416  including an electrical connector  410 . The electrical connector  410  includes a body portion  422  and terminals  424 . The terminals  424  extend from the body portion  422  and diverge from each other. That is, the terminals  424  do not cross over each other when viewed in the lateral cross section. 
         [0053]    The principle and mode of operation of this invention have been explained and illustrated in its preferred embodiments. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.