Abstract:
A lead frame assembly which allows for the connection of multiple individual fixed components in various locations, while alleviating tolerance concerns by having a flexible lead frame. The lead frame assembly includes several sub-lead frames, and a plurality of interconnects which connect each of the sub-lead frames together. The lead frame assembly also includes a plurality of segments, and each segment surrounds one of the sub-lead frames, to electrically isolate each sub-lead frame. Various components are electrically connected by incorporating stamped receptacles, or slot terminals, in the sub-lead frames. The interconnects along with plastic voids allow the various attached components to have tolerance flexibility relative to one another, as various components are attached to each of the slot terminals.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/924,885 filed Jan. 8, 2014. The disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to a lead frame assembly which has more than one flexible interconnect used to provide a flexible connection between various sub-lead frames, compensating for tolerance variations in components connected to the lead frame assembly. 
     BACKGROUND OF THE INVENTION 
     Lead frames are commonly used to provide connection between various electrical components. Typical lead frames are rigid overmolded structures that are assembled with other components during an assembly process. Because the lead frames are rigid, there is very little adjustment available, and therefore little allowance for flexibility of component location tolerances. These tolerances may vary as a result of dimensional fluctuations which occur during the manufacturing process, or from exposure to different temperatures, where the lead frame, overmolding, and components connected to the lead frame have different coefficients of thermal expansion, leading to inconsistent dimensional fluctuations during thermal cycling. Some components, due to the nature of their construction, may require more flexibility with regard to positioning relative to the lead frame, ensuring a proper connection with minimal stress on the lead frame. 
     Accordingly, there exists a need for a lead frame which provides suitable connection between various electrical components, and allows for flexibility of component location tolerances which may occur during the manufacturing process, or from exposure to thermal cycling. 
     SUMMARY OF THE INVENTION 
     The present invention is a lead frame assembly which allows for the connection of multiple individual fixed components in various locations, while alleviating tolerance concerns by having a flexible lead frame. Various components are electrically connected by incorporating stamped receptacles, or slot terminals, in the lead frame. Interconnects along with plastic voids allow the various attached components to have flexibility relative to one another after shipping carrier strips are removed. 
     In one embodiment, the lead frame assembly of the present invention includes several sub-lead frames, and a plurality of interconnects which connect each of the sub-lead frames together. The interconnects allow for movement in multiple directions of the sub-lead frames relative to one another. 
     Each of the interconnects includes a first arc portion connected to one of the sub-lead frames, a second arc portion connected to the first arc portion, and a third arc portion connected to the second arc portion and another of the sub-lead frames. The first arc portion, second arc portion, and third arc portion deflect to allow for relative movement between two or more of the sub-lead frames. 
     The lead frame assembly includes a plurality of segments, and each segment surrounds one of the sub-lead frames, through a process such as overmolding, and functions as a housing. There is also a plurality of terminals, and each of the terminals is connected to one of the sub-lead frames. While each segment substantially surrounds a corresponding sub-lead frame, the interconnects and the terminals are still exposed, and not surrounded by the segments. In one embodiment, the terminals are M-slot terminals, and electrical components are connected to the M-slot terminals. 
     In one embodiment, there are seven sub-lead frames connected in series, and seven segments. A first sub-lead frame is connected to a second sub-lead frame, the second sub-lead frame is connected to a third sub-lead frame, a fourth sub-lead frame connected to the third sub-lead frame, a fifth sub-lead frame is connected to the fourth sub-lead frame, a sixth sub-lead frame connected to the fifth sub-lead frame, and a seventh sub-lead frame is connected to the sixth sub-lead frame. The connection of each of the sub-lead frames together using the interconnects allows for each sub-lead frame to move transversely relative to one another, depending upon the configuration of the interconnects. 
     The sub-lead frames are connected to each other using different amounts of interconnects in different configurations. In one embodiment, there are three interconnects connecting one of the sub-lead frames to another of the sub-lead frames, and the three interconnects are configured such that one of the interconnects is offset from the other two interconnects. The interconnects also may be configured such that more or less interconnects are used to connect two of the sub-lead frames together, and are either aligned or offset from one another. 
     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 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a lead frame assembly having at least one flexible interconnect, according to embodiments of the present invention; 
         FIG. 2  is a perspective view of a lead frame assembly having at least one flexible interconnect, with the segments removed, according to embodiments to the present invention; 
         FIG. 3  is a perspective view of a lead frame assembly having at least one flexible interconnect, with the carrier brackets attached, according to embodiments of the present invention; 
         FIG. 4  is a second perspective view of a lead frame assembly having at least one flexible interconnect, according to embodiments of the present invention; 
         FIG. 5  is an enlarged view of the circled portion shown in  FIG. 4   
         FIG. 6  an enlarged view of a flexible interconnect, used with a lead frame assembly, according to the present invention; and 
         FIG. 7  is s sectional side view of part of a pressure sensor and a lead frame assembly connected together, according to embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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. 
     A diagram of a lead frame assembly according to the present invention is shown in the Figures generally at  10 . The lead frame assembly  10  includes sub-lead frames, shown generally at  10 A- 10 G, respectively, which are connected together by a plurality of interconnects  14   a   1 - 14   f   4 . Each sub-lead frame  10 A- 10 G has a corresponding segment  12   a - 12   g , each of which functions as a housing for each of the sub-lead frames  10 A- 10 G. The segments  12   a - 12   g  are made of a plastic material, but it is within the scope of the invention that other types of materials may be used. 
     Each interconnect  14   a   1 - 14   f   4  includes a plurality of arc portions, shown in  FIGS. 5-6 . An example of one of the interconnects  14   a   1  is shown in  FIG. 6 , where the interconnect  14   a   1  is used to connect part of the first sub-lead frame  10 A to part of the second sub-lead frame  10 B. However, the other interconnects  14   a   2 - 14   f   4  are constructed and connected to the sub-lead frames  10 A- 10 G in a similar manner. The interconnect  14   a   1  includes a first arc portion  16   a  connected to a second arc portion  16   b , and the second arc portion  16   b  is connected to a third arc portion  16   c . The first arc portion  16   a  is also connected to and formed as part of the first sub-lead frame  10 A, and the third arc portion  16   b  is also connected to and formed as part of the second sub-lead frame  10 B. Portions of the segments  12   a - 12   g  may be overmolded onto the respective sub-lead frames  10 A- 10 G, but it is within the scope of the invention that the segments  12   a - 12   g  may be connected to the sub-lead frames  10 A- 10 G in other ways. 
     Each sub-lead frame  10 A- 10 G includes a plurality of slot terminals, which in this embodiment are M-slot terminals  18 , which are integrally formed with the sub-lead frames  10 A- 10 G. While it has been mentioned that the segments  12   a - 12   g  may be overmolded around the sub-lead frames  10 A- 10 G, the segments  12   a - 12   g  do not surround the M-slot terminals  18  (to allow components to connect to the M-slot terminals  18 ) or the interconnects  14   a   1 - 14   f   4  (to allow the interconnects  14   a   1 - 14   f   4  to deflect). Various electrical components are connected to the M-slot terminals  18 , such as solenoids, semi-conductor chips, pressure sensors, and the like. More specifically, as shown in  FIG. 2 , the lead frame assembly  10  is shown with the segments  12   a - 12   g  removed, and the lead fame assembly  10  has the plurality of sub-lead frames  10 A- 10 G, where each of the sub-lead frames  10 A- 10 G has one or more of the M-slot terminals  18 . Each of the sub-lead frames  10 A- 10 G are connected to one another using the interconnects  14   a   1 - 14   f   4 , therefore placing the M-slot terminals  18  in electrical communication with one another. Various components may be connected to one or more of the M-slot terminals  18 , and, depending on the configuration of the M-slot terminals  18  and the sub-lead frames  10 A- 10 G, the M-slot terminals  18  may be in communication one or more of the other M-slot terminals  18  connected to the different sub-lead frames  10 A- 10 G. 
     The interconnects  14   a   1 - 14   f   4  are also in varying locations throughout the different sub-lead frames  10 A- 10 G. Some of the interconnects  14   a   1 - 14   f   4  are aligned with one another as well. Because the interconnects  14   a   1 - 14   f   4  are not overmolded and protected by the segments  12   a - 12   g , the interconnects  14   a   1 - 14   f   4  are exposed. The interconnects  14   a   1 - 14   f   4  are separated by isolation features  24   a,b  formed as part of the segments  12   a - 12   g , and configured in the manner shown in the Figures to prevent shorting between the interconnects  14   a   1 - 14   f   4 . There are two types of isolation features  24   a,b , there are recesses  24   a  formed as part of the segments  12   a - 12   g , as well as wall portions  24   b  formed as part of the segments  12   a - 12   g . If the lead frame assembly  10  is used as part of a transmission, there are instances where the lead frame assembly  10  may be exposed to pieces of metal, or “slivers,” in the transmission. These metal slivers contacting two or more of the interconnects  14   a   1 - 14   f   4  may cause electrical shorting between the interconnects  14   a   1 - 14   f   4 . The isolation features  24   a , 24   b  electrically isolate the interconnects  14   a   1 - 14   f   4  from one another, preventing electrical shorting by limiting occurrence of a metal sliver coming in contact with more than one interconnect  14   a   1 - 14   f   4 . 
     In one embodiment, the sub-lead frames  10 A- 10 G and the different segments  12   a - 12   g  are shaped differently, such that the segments  12   a - 12   g  are overmolded around the sub-lead frames  10 A- 10 G, but not the interconnects  14   a   1 - 14   f   4 , as described above. The interconnects  14   a   1 - 14   f   4  are configured in groups to provide a flexible connection between each of the sub-lead frames  10 A- 10 G. More specifically, there are joints, shown generally at  22   a - 22   f , made up of varying amounts of interconnects  14   a   1 - 14   f   4 , which provide the connection between the various sub-lead frames  10 A- 10 G. The position and amount of interconnects  14   a   1 - 14   f   4  used to connect the various sub-lead frames  10 A- 10 G affects how much the sub-lead frames  10 A- 10 G may move transversely relative to one another, as indicated by arrows  26 . 
     The first joint, shown generally at  22   a , connects the first two sub-lead frames  10 A, 10 B, the second joint, shown generally at  22   b , connects the second and third sub-lead frames  10 B, 10 C, the third joint, shown generally at  22   c , connects the third and fourth sub-lead frames  10 C, 10 D, the fourth joint, shown generally at  22   d , connects the fourth and fifth sub-lead frames  10 D, 10 E, the fifth joint, shown generally at  22   e , connects the fifth and sixth sub-lead frames  10 E, 10 F, and the sixth joint, shown generally at  22   f , connects the sixth and seventh sub-lead frames  10 F, 10 G. 
     The first joint  22   a  has the first interconnect  14   a   1 , a second interconnect  14   a   2 , and a third interconnect  14   a   3 , where the first interconnect  14   a   1  and the third interconnect  14   a   3  are in substantial alignment with one another, and the second interconnect  14   a   2  is offset from the first interconnect  14   a   1  and the third interconnect  14   a   3 . The interconnects  14   a   1 - 14   a   3  are configured such that the interconnects  14   a   1 , 14   a   3  are offset from the second interconnect  14   a   2 , and are also surrounded by recesses  20   a  formed as part of the segments  12   a , 12   b  to electrically isolate the interconnects  14   a   1 - 14   a   3  from one another, as shown in FIGS.  1  and  3 - 5 , to prevent shorting. The interconnects  14   a   1 - 14   a   3  allow the first sub-lead frame  10 A and second sub-lead frame  10 B to move transversely relative to one another in the direction of the arrows indicated at  26 . 
     The second joint  22   b  includes four interconnects  14   b   1 ,  14   b   2 ,  14   b   3 ,  14   b   4 . The interconnects  14   b   2  and  14   b   3  are in substantial alignment with one another, and the interconnects  14   b   1  and  14   b   4  are offset from one another and the interconnects  14   b   2  and  14   b   3 . This allows the second sub-lead frame  10 B and third sub-lead frame  10 C to move transversely relative to one another in the direction of the arrows indicated at  26 . The interconnects  14   b   1  and  14   b   4  are partially disposed in recesses  24   a  formed as part of the second and third segments  12   b , 12   c , and the other interconnects  14   b   2  and  14   b   3  of the second joint  22   b  are adjacent various wall portions  24   b  formed as part of the second and third segments  12   b , 12   c . The recesses  24   a  and wall portions  24   b  electrically isolate the interconnects  14   b   1 - 14   b   4  from one another, to prevent electrical shorting. 
     The third joint  22   c  connects the third sub-lead frame  10 C and the fourth sub-lead frame  10 D. The third joint  22   c  includes five interconnects  14   c   1 - 14   c   5 , and the first four interconnects  14   c   1 - 14   c   4  of the third joint  22   c  are adjacent various wall portions  24   b  formed as part of the third and fourth segments  12   c , 12   d , and the last interconnect  14   c   5  is partially surrounded by recesses  24   a  formed as part of the third and fourth segments  12   c , 12   d , to prevent electrical shorting between the interconnects  14   c   1 - 14   c   5 . The interconnects  14   c   1 - 14   c   5  allows the third sub-lead frame  12   c  and the fourth sub-lead frame  12   d  to move transversely relative to one another in the direction of the arrows  26 . 
     The fourth joint  22   d  allows for relative transverse movement between the fourth sub-lead frame  10 D and the fifth sub-lead frame  10 E, as indicated by the arrows  26 . The fourth joint  22   d  includes six interconnects  14   d   1 , 14   d   2 , 14   d   3 , 14   d   4 , 14   d   5 , 14   d   6 , where the interconnects  14   d   2 , 14   d   4 , 14   d   6  are in alignment with one another, and the remaining interconnects  14   d   1 , 14   d   3 , 14   d   5  are offset from one another, and from the interconnects  14   d   2 , 14   d   4 , 14   d   6 . Each of the interconnects  14   d   1 - 14   d   6  are partially surrounded by recesses  24   a  of various shapes formed as part of the fourth segment and fifth segment  12   d , 12   e , to electrically isolate the interconnects  14   d   1 - 14   d   6  from one another, to prevent electrical shorting. 
     The fifth joint  22   e  includes five interconnects  14   e   1 ,  14   e   2 ,  14   e   3 ,  14   e   4 ,  14   e   5 . The second and third interconnects  14   e   2 , 14   e   3  are in substantial alignment with one another, and the first interconnect  14   e   1 , fourth interconnect  14   e   4 , and fifth interconnect  14   e   5  of the fifth joint  22   e  are offset from one another and the second and third interconnects  14   e   2 ,  14   e   3 . This allows the fifth sub-lead frame  10 E and the sixth sub-lead frame  10 F to move transversely relative to one another in the direction of the arrows  26 . The first interconnect  14   e   1 , fourth interconnect  14   e   4 , and fifth interconnect  14   e   5  of the fifth joint  22   e  are at least partially surrounded by recesses  24   a  formed as part of the fifth segment  12   e  and the sixth segment  12   f , and the second interconnect  14   e   2  and third interconnect  14   e   3  are surrounded by wall portions  24   b  formed as part of fifth segment  12   e  and the sixth segment  12   f , which prevents electrical shorting between the interconnects  14   e   1 - 14   e   5 . 
     The sixth joint  22   f  includes four interconnects  14   f   1 , 14   f   2 , 14   f   3 , 14   f   4 , which connect the sixth sub-lead frame  10 F and the seventh sub-lead frame  100 . The second and third interconnects  14   f   2 , 14   f   3  of the sixth joint  22   f  are in substantial alignment with one another, and the first and fourth interconnects  14   f   1 , 14   f   4  are offset from one another, and are offset from the second and third interconnects  14   f   2 , 14   f   3 . The interconnects  14   f   1 - 14   f   4  allow for the sixth sub-lead frame  10 F and the seventh sub-lead frame  100  to move transversely relative to one another in the direction of the arrows  26 . Also, each of the interconnects  14   f   1 - 14   f   5  of the sixth joint are partially disposed in recesses  24   a  of various shapes formed as part of the sixth segment  12   g  and the seventh segment  12   g.    
     While it has been shown that some of the interconnects  14   a   1 - 14   f   4  are offset from one another, and others are not, it is within the scope of the invention that the configuration of the various joints  22   a - 22   e  may be changed to have different interconnects  14   a   1 - 14   f   4  offset from one another in a different configuration other than was is described above, to allow the different sub-lead frames  10 A- 10 G to move differently than what is shown in the Figures, and allow for the M-slot terminals  18  to be configured differently, making the lead frame assembly  10  suitable for different applications. 
     In this embodiment, the lead frame assembly  10  is connected to a main lead frame and various sensors, where the sensors have fixed positions. The main lead frame may be part of a transmission control unit (TCU) or the like. The fourth sub-lead frame  10 D is the largest of the sub-lead frames  10 A- 10 G, and includes eight M-slot terminals  18 , which are in electrical communication with the M-slot terminals  18  of the other sub-lead frames  10 A- 10 C and  10 E- 10 G. The fourth segment  12   d  overmolded around the fourth sub-lead frame  10 D includes two mounting apertures  28 , which are used to connect the fourth segment  12   d  and fourth sub-lead frame  10 D to the main lead frame of the TCU. The connection between the main lead frame and the mounting apertures  28  may be a snap-fit connection, or the like. 
     Referring to  FIGS. 1 ,  3 - 4 , and  7 , each of the segments  12   a - 12   c  and  12   e - 12   g  also include alignment apertures  30 , which are smaller than the mounting apertures  28  formed as part of the fourth segment  12   d . In one embodiment, each of the remaining segments  12   a - 12   c  and  12   e - 12   g  is connected to a pressure sensor  32  having the connector pins  34 , an example of which is shown in  FIG. 7 . The alignment apertures  30  provide proper alignment so the connector pins  34  may be properly inserted through the M-slot terminals  18 , as shown in  FIG. 7 . The pressure sensor  32  includes an alignment post  38 , which extends into the alignment aperture  30  of the first segment  12   a , as shown in  FIG. 7 , when the lead frame assembly  10  is connected to the main lead frame of the TCU. 
     Each of the M-slot terminals  18  include a plurality of tabs, which in this embodiment are three tabs  36 , which are curved in a first direction, or upwardly as shown in  FIGS. 1-4  and  7 . It is also shown that the tabs  36  are configured such that two of the tabs  36  apply force to a first side of the connector pin  34 , and another of the tabs  36  applies force to a second side of the connector pin  34 . The pin  34  receiving force from the tabs  36  on both sides of the pin  34  stabilizes the pin  34 , and ensures the pin  34  remains in electrical communication with the corresponding M-slot terminal  18 , and secures the connection between the pin  34  and the corresponding M-slot terminal  18 . 
     As mentioned above, the fourth sub-lead frame  10 D is the largest of the sub-lead frames  10 A- 10 G, and includes eight M-slot terminals  18 . The M-slot terminals  18  of the fourth sub-lead frame  10 D are substantially the same as the M-slot terminals  18  of the other sub-lead frames  10 A- 10 C and  10 E- 10 G, with the exception that the tabs  36  are curved in a second direction, or downwardly as shown in  FIGS. 1-4  and  7 . The tabs  36  of the M-slot terminals  18  of the fourth sub-lead frame  10 D are angled downwardly to engage with the connector pins (not shown) which are part of the main lead frame of the TCU in a similar manner as the connector pins  34  of the pressure sensors  32 . 
     During assembly, the fourth sub-lead frame  10 D and fourth segment  12   d  are connected to the main lead frame of the TCU first, where the main lead frame of the TCU has connecting features that are disposed in the mounting apertures  28  to connect to the fourth segment  12   d , and the main lead frame of the TCU has connector pins that are inserted into the M-slot terminals  18  of fourth sub-lead frame  10 D. Once the fourth sub-lead frame  10 D and fourth segment  12   d  are connected to the main lead frame of the TCU, the remaining sub-lead frames  10 A- 10 C,  10 E- 10 G and segments  12   a - 12   c ,  12   e - 12   g  are then connected to pressure sensors  32  in the same manner as the connection of the first sub-lead frame  10 A and first segment  12   a  to the pressure sensor  32  as shown in  FIG. 7 . If there are variations in the locations of the pressure sensors  32 , then the interconnects  14   a   1 - 14   f   4  are able to deflect, allowing the sub-lead frames  10 A- 10 C,  10 E- 10 G to move, and therefore compensate for the variations in these locations, and the remaining sub-lead frames  10 A- 10 C,  10 E- 10 G and segments  12   a - 12   c ,  12   e - 12   g  are then connected to the other pressure sensors  32 . 
     The sub-lead frames  10 A- 10 G being connected through the use of the interconnects  14  provides the functionality of compensating for component location tolerances, where the variation in the location of the pressure sensors  32  may be caused by thermal expansion, variation in the dimensions of the pressure sensors  32  occurring during the manufacturing process, or the like. The variations in component location may cause difficulty in connecting the components to the terminals  18  of each of the sub-lead frames  10 A- 10 G if there was nothing to compensate for these variations. The interconnects  14  allow for movement between the sub-lead frames  10 A- 10 G, which therefore provides the functionality of allowing the electrical components, such as the pressure sensors  32 , to have variations in their respective locations, and still be connected to the lead frame assembly  10 . In one embodiment, the interconnects  14  are stamped components, but it is within the scope of the invention that other manufacturing processes may be used. 
     The lead frame assembly  10  also includes several carrier brackets  20 , which provide rigidity to the lead frame assembly  10  when the lead frame assembly  10  is transported from one location to the next during the manufacturing process. When the carrier brackets  20  are connected to the segments  12   a - 12   g , the lead frames  10 A- 10 G are prevented from moving relative to one another. The rigidity is beneficial during transportation between manufacturing facilities, and within a single manufacturing facility. 
     Once the carrier brackets  20  are removed, the various electrical components are connected to the lead frame assembly  10 , and the interconnects  14  allow for flexible movement between the sub-lead frames  10 A- 100 , to provide the ability to connect to different components, such as the pressure sensors  32 , as described above. 
     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.