Flexible lead frame connection for electronic interconnects

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.

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.

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.

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.

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.

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.