Electrical terminal for flat flexible cable

Abstract

An electrical terminal (30) for mating with an exposed conductor (12) of a flat flexible cable (10) includes an electrical contact (32) and a crimp portion extending from the electrical contact in a longitudinal direction of the terminal for crimping to the conductor of the flat flexible cable (10). The crimp portion includes a base (44) defining at least one tab extending therefrom, a first side wall extending from the base and including a first portion (56) attached to the base and a second portion (57) attached to the first portion at an end opposite the base, and a second side wall extending from the base. The base and the first and second side walls define an opening (70) configured to receive the conductor. In a crimped state of the terminal (30), the first portion of the first side wall is folded into the opening to crimp the conductor within the opening and against the tab, and the second portion of the first side wall is folded to overlap a side of the first portion opposite the conductor.

Description

TECHNICAL FIELD

[0001] The present invention relates to electrical terminals, and more particularly to electrical terminals adapted to crimp a conductor to a flat flexible cable. BACKGROUND

[0002] As understood by those skilled in the art, a flat flexible cable (FFC) or flat flexible circuit is an electrical component composed of at least one conductor (e.g., a metal foil) embedded in a thin, flexible insulating tape. FFCs are gaining popularity in many industries due to advantages over traditional "round wire" counterparts. Specifically, in addition to having a lower profile and lighter weight, FFCs also enable larger circuit paths to be implemented more easily as compared to round wire based architectures. As a result, FFCs are being considered for many complex and / or high volume applications, including wiring harnesses, such as those used in automotive manufacturing.

[0003] Implementing or integrating FFCs in existing wiring environments presents significant challenges. In automotive applications, as an example only, FFC based wiring harnesses can need to mate with hundreds of existing components, including sub-harnesses and various electronic devices (e.g., lights, sensors, etc.), each of which has an established (in some cases standardized) connector or interface type. Thus, one key obstacle hindering implementation of FFCs in these applications includes the need to develop a fast, robust and low resistance termination technique that enables FFCs to be connected to mate with these existing connections.

[0004] A typical FFC can be implemented by applying an insulating material on either side of a pre-patterned thin foil conductor and adhering the sides together via an adhesive to enclose the conductor therein. Current FFC terminals include a piercing crimp terminal in which a tine of the terminal is used to pierce the insulating and adhesive material of the FFC in an attempt to establish a secure electrical connection with the embedded conductor. However, due in part to the fragility of the thin foil conductor material itself, these types of terminals have several drawbacks, including significantly higher electrical resistance as compared to traditional round wire F-style crimps, inconsistent electrical connections between the conductor and the terminal, and mechanical unreliability over time in harsh environments.

[0005] Accordingly, there is a need for an improved electrical terminal and accompanying termination technique to enable FFCs to be adapted to these environments. SUMMARY

[0006] According to embodiments of the present disclosure, a terminal is provided for mating with an exposed conductor of a flat flexible cable. The terminal includes an electrical contact and a crimp portion extending from the electrical contact in a longitudinal direction of the terminal to crimp to the conductor of the flat flexible cable. The crimp portion includes a base defining at least one protrusion extending therefrom; and first and second side walls extending from the base. The base and the side walls define an opening configured to receive the conductor of the flat flexible cable therein. The first side wall includes a first portion attached to the base and a second portion attached to the first portion at an end opposite the base. In a crimped state of the terminal, the first portion of the first side wall is folded into the opening to crimp the conductor within the opening and against the protrusion, and the second portion of the first side wall is folded to overlap a side of the first portion opposite the conductor.

[0007] A cable assembly according to embodiments of the present disclosure includes a flat flexible cable having a plurality of conductors embedded within an insulating material. A portion of each conductor is exposed via an opening selectively formed in the insulating material, allowing a crimp portion of a conductive terminal to engage the conductor within the opening. The crimp portion of the terminal includes a base defining at least one protrusion extending therefrom; and first and second side walls extending from the base. The base and the first and second side walls define an opening configured to receive the conductor therein. The first side wall includes a first portion attached to the base and a second portion attached to the first portion at an end opposite the base. In a crimped state of the terminal, the first portion of the first side wall is folded into the opening to crimp the conductor within the opening and against the protrusion, and the second portion of the first side wall is folded in a direction opposite the first portion to overlap the first portion on a side opposite the conductor. BRIEF DESCRIPTION OF DRAWINGS

[0008] The application will now be described, by way of example, with reference to the accompanying drawings, in which:

[0009] Figure 1 is a top view of an exemplary FFC configured for use with a terminal according to embodiments of the present disclosure;

[0010] Figure 2 is a perspective view of a plurality of terminals according to embodiments of the present disclosure installed in an exemplary connector body;

[0011] Figure 3 is a perspective view of an FFC of Figure 2 mating with the terminal and connector body of Figure 1

[0012] Figure 4A is a perspective view of a crimp portion of a terminal according to a first embodiment of the present disclosure in an uncrimped state;

[0013] Figure 4B is a perspective view of a crimp portion of a terminal according to a second embodiment of the present disclosure in a crimped state; Figure 4A ​A partial perspective view of the crimped portion;

[0014] Figure 4C yes Figure 4A and 4B A front cross-sectional view of the crimped portion;

[0015] Figure 4D It is in a crimping state. Figures 4A-4C A perspective view of the crimped portion;

[0016] Figure 4E yes Figure 4D A front cross-sectional view of the crimped portion;

[0017] Figure 5 This is a perspective view of the crimped portion of a terminal according to a second embodiment of the present disclosure;

[0018] Figure 6A This is a perspective view of the crimped portion of a terminal according to a third embodiment of the present disclosure; and

[0019] Figure 6B yes Figure 6A A front cross-sectional view of the crimped portion. Detailed Implementation

[0020] Reliably crimping terminals onto the thin conductor of an FFC requires a method to address the risk of failing to form a proper (or any) electrical contact with the conductor, or damaging the conductor by applying excessive pressure. This has proven difficult, partly due to the thin nature of the FFC conductor compared to the tolerances of typical crimp terminals. For example, with a thickness less than one-tenth of a millimeter (mm) (e.g., 0.07 mm), the crimp height tolerance can easily exceed the conductor thickness, potentially resulting in a complete lack of electrical contact between the terminal and conductor, or crushing or damaging the conductor, even under proper crimping operations. As will be explained in more detail herein, embodiments of this disclosure aim to overcome these difficulties by providing crimpable terminals capable of achieving reliable, low-resistance connections in a large number of termination or crimping operations.

[0021] The terminals according to embodiments of this disclosure can be configured for use with FFC, for example... Figure 1An exemplary portion of the FFC 10 is shown. As illustrated, the FFC 10 typically includes a plurality of conductors 12 embedded within an insulating material 14. The conductors 12 may include metal foil, such as copper foil on the order of 0.07 mm in thickness, which is merely an example and can be patterned in any desired configuration. The insulating material 14, such as a polymer insulating material, may be applied to either side of the conductors 12 via an adhesive material to form an embedded conductor arrangement. The exemplary FFC 10 includes a plurality of segments 20, 22, 24, each segment containing a plurality of conductors 12. Corresponding windows or openings 21, 23, 25 are selectively formed or defined near the respective ends of segments 20, 22, 24 to expose the conductors 12, thereby enabling their connectorization using terminals according to embodiments of the present disclosure. The windows or openings may be formed at any desired location in the insulating material 14 to expose portions of the conductors 12 for termination. Additional openings 16 may be provided and configured to receive complementary features of the associated connector, as will be described in more detail herein.

[0022] refer to Figure 2 An exemplary inner housing 26, forming part of the connector, is provided for securing to... Figure 1 The FFC 10 is provided as an example only. As shown, the inner housing 26 is pre-mated with a plurality of conductive terminals 30 according to embodiments of the present disclosure. Each terminal 30 typically includes an electrical contact or mating end 32, in this case a female mating end, configured to receive a corresponding male terminal to establish an electrical connection. The mating end 32 may include one or more locking features 33 configured to engage with the inner housing 26 to secure the terminal 30 thereto. The rear end 34 of the terminal 30 opposite the mating end 32 may include piercing elements 35, embodied herein as a pair of sharp teeth. Arranged between the mating end 32 and the rear end 34 is a crimping portion 36 configured to elastically deform to crimp onto a conductor disposed therein.

[0023] Figure 3 The diagram illustrates an intermediate step in the connectorization process of FFC 10. As shown, FFC 10 is placed on top of multiple connectors, including... Figure 2 The connector has an inner housing 26 and two second inner housings 28. Each connector's terminal 30 receives an exposed conductor 12 within its respective crimp portion 36, which extends through windows 21, 23, 25 formed in the insulating material 14 of the FFC10 (see...). Figure 1The crimping portion 36 is configured to crimp onto the conductor 12, for example, in a batch termination or crimping step, wherein the crimping portion 36 of each terminal 30 is crimped simultaneously, securing the terminal 30 and thus the inner housings 26, 28 to the FFC 10. The inner housings 26, 28 may also define strain-relieving portions 37, 38, configured to extend through the opening 16 in the FFC 10, for further securing the inner housings 26, 28 to the FFC 10. Similarly, as shown, the piercing element 35 penetrates the insulating material 14 of the FFC 10 and may subsequently be flattened or otherwise deformed to further secure the terminal 30 to the FFC 10. In this way, the piercing element 35 and the strain-relieving portions 37, 38 provide a strain-relieving form for the resulting connection, mechanically securing the position of the FFC 10 relative to the terminal 30.

[0024] Figures 4A-4E Terminals configured for use with FFC according to this disclosure are shown (e.g. Figure 2 and Figure 3 An embodiment of the crimping portion 40 of terminal 30 is shown; the remaining terminals are not shown. (See reference...) Figures 4A-4C In its uncrimped state, the crimped portion 40 includes a generally U-shaped body 42 comprising a base 44 and two generally opposing sidewalls or wings 46, 48 extending from either side in a direction generally perpendicular to the base 44. A contact or conductor receiving opening or space 70 is defined between the sidewalls 46, 48 and configured (e.g., sized and shaped) to receive an exposed conductor of the FFC (e.g., along the axial direction of the terminal). Figure 1 and Figure 3 The conductor 12 shown. Each sidewall or wing 46, 48 may be defined by two parts, as in Figure 4B and 4C This is shown more clearly in the diagram. Specifically, the first sidewall 46 includes a first portion 56 extending from and adjacent to a first end of the base 44, and a second portion 57 extending from an end of the first portion. The first portion 56 and the second portion 57 may be continuous and coherent with each other, or they may be partially separate. For example, a relief or recess 72 (which may be embodied as a scribe line) is formed partially through the middle portion of the sidewall 46 in a direction transverse to the longitudinal direction of the terminal, wherein the first portion 56 and the second portion 57 are located on corresponding sides of the recess 72. The recess 72 may extend in the longitudinal direction of the terminal and along the entire length of the sidewall 46. The recess 72 is configured to facilitate bending between each of the first portion 56 and the second portion 57 during a crimping operation, such that the second portion can be more easily “folded back” over the first portion, as... Figure 4D and 4EThe crimped state of the terminals is shown in the diagram. This folding can be further achieved by forming a second recess or undercut 73 in the region of the recess or protrusion 72 in each longitudinal end of the first sidewall 46, such that the recess 72 leads to or communicates with the undercut 73. The undercut 73 extends generally in its axial or longitudinal direction into the sidewall 46 to a predetermined depth, and a portion of the undercut 73 is formed in each of the first and second sidewall portions 56, 57.

[0025] like Figure 4C As shown, the first portion 56 and the second portion 57 may each extend in different directions relative to the base 44. More specifically, the first portion 56 may extend substantially perpendicularly from the base 44, while the second portion 57 extends at a non-zero angle from the end of the first portion 56 (or at a non-perpendicular angle relative to the base 44) and in a direction substantially away from the center of the crimping portion 40. The angled nature of the second portion 57 relative to the first portion 56 facilitates crimping or folding the second portion 57 relative to the first portion 56 in the desired direction by means of a force applied in a downward direction to the top of the second portion 57. As shown, the second sidewall 48 includes first and second portions having features similar to those of the first sidewall 46 described above, such as corresponding reliefs and / or undercuts defined therein, which will not be described in detail here.

[0026] refer to Figure 4D and 4E The crimped portion 40 is shown in a crimped state, wherein the opposing sidewalls 46, 48 are formed from... Figures 4A-4C The orientation shown is crimped or deformed in the manner described in the folding-back configuration. As shown, the first portion 56 and the second portion 57 of the first sidewall 46 have been folded or crimped relative to the base in a generally parallel orientation, with the first portion 56 folded or rotated relative to the base in a first direction, and the second portion 57 folded in a direction opposite to the first direction such that it overlaps the first portion 56 in an opposite or adjacent manner. The second sidewall 48 is crimped in a similar but opposite direction to the first sidewall 46. The sidewalls 46 and 48 can be folded or crimped simultaneously by applying a single downward force to their free ends, allowing for faster termination compared to the multi-step crimping process required for other terminal types. Figure 4E An exemplary cross-sectional view of the crimped portion 40 in a crimped state is provided, including a conductor 100 crimped within a receiving space 70 by sidewalls 46, 48.

[0027] As described above, reliably crimping a thin foil conductor to an FFC requires a method to address the risk of failing to form a proper electrical contact with the conductor or damaging the conductor by applying excessive pressure. Embodiments of this disclosure address this problem by introducing several additional features on or within the base 44 of the crimp portion 40 to prevent any of the aforementioned failures.

[0028] Referring again to embodiments 4A-4E, the crimp portion 40 includes an axially extending protrusion or protruding structure 60 that rises from the base 44 and / or from the lower end of the first or second sidewalls 46, 48 into the receiving opening 70. In the illustrated embodiment, the protrusion 60 includes a plurality of segments, including a pair of outer compression restraints 64 defined by raised protrusions extending vertically from the base 44 into the receiving opening 70. Similarly, a central compression restraint 66 is defined by a protrusion arranged generally between the outer compression restraints 64. In an exemplary embodiment, each compression restraint 64, 66 includes an externally curved or rounded profile whose axis of curvature is generally parallel to the axial or longitudinal direction of the terminal and / or conductor disposed therein. The outer compression restraint 64 also includes a rounded end 65 extending in the respective vertical direction. Figure 4D As shown, at least a portion of each external compression limiter 64 extends axially through the ends of the first and second sidewalls 46, 48 to ensure maximum contact area with the conductor crimped within the terminal.

[0029] Partly due to their bending nature, compression limiters are configured (i.e., sized and shaped) to compress the conductor under the force of the first and second sidewalls of the crimping in a manner that prevents damage to the conductor. Furthermore, the increased height of the compression limiter ensures reliable electrical contact with the conductor at all times, resolving the aforementioned tolerance-related issues present in prior art crimping solutions. Additionally, the height of the compression limiter can be selected to allow for adjustment of the crimping height and compression force for a given application (e.g., for conductors of different thicknesses).

[0030] Also refer to Figures 4A-4E The protrusion 60 also includes a protruding spring portion or actuator 68 formed between the outer compression limiter 64 and the central compression limiter 66. Each spring portion 68 may be at least partially disposed within a corresponding hole 69 formed through the base 44. Each spring portion 68 may include a curved or circular profile extending into the receiving opening 70 and its axis of curvature oriented parallel to the axial direction of the terminal. In one embodiment, the radius of curvature of the spring portion 68 substantially matches the radius of curvature of the compression limiters 64, 66. The spring portion 68 may extend above the compression limiters 64, 66, and thus further vertically into the receiving opening or space 70. The spring portion 68 may be embodied as a cantilever spring, each cantilever spring having a free end and a fixed end, the fixed end being attached to or extending from the corresponding sidewall 46, 48 (or base 44) to provide additional elasticity. In other embodiments, the spring portion 68 may comprise a uniformly supported leaf spring, each spring portion 68 being attached at each end to a corresponding sidewall 46, 48 (or base 44).

[0031] Spring portions 68 and compression limiters 64, 66 form generally continuous circular protrusions 60 extending axially within the receiving opening 70. However, a nominal gap or clearance may be defined between the spring portions 68 and the compression limiters 64, 66 through the base, allowing them to move or deform independently. Additionally, the edges of each spring portion 68 extending transversely to the longitudinal direction of the terminal improve engagement with the conductor crimped within the terminal and thus improve electrical contact. The spring portions 68 are configured (i.e., sized and shaped) to ensure upward pressure is maintained on the conductor crimped within the terminal, further improving electrical contact with the sidewalls of the crimping portion 40.

[0032] Figure 5 , 6A Figures 6B and 6B illustrate additional embodiments of this disclosure. These embodiments may include those described above. Figures 4A-4D The embodiments described herein depict similar features, wherein only the relevant differences between them are described herein. For example, according to Figure 5 The crimping portion 80 of one embodiment includes a compression limiter 83 that defines a single elongated protrusion extending in the axial direction of the terminal. The compression limiter 83 may extend substantially along the entire length of the crimping portion 80 or along a length substantially equal to the length of the two sidewalls 85, 86 configured to be crimped to a conductor disposed within the crimping portion, along the base 84. The compression limiter 83 tapers in all directions from the center of its protrusion toward the base 84 and does not define a plane. Figure 5 The sidewalls 85, 86 of the embodiments may include those described above regarding Figures 4A-4E The similar characteristics described.

[0033] exist Figure 6A and 6B In the embodiment of the crimp portion 90 shown, two cantilevered protrusions 94 extend from their respective sidewalls and at least partially into corresponding holes 96 formed through the base of the crimp portion. The free end of each protrusion 94 may be bent upwards or formed linearly upwards (i.e., protruding at a non-zero angle relative to the base) to extend into the receiving opening of the terminal. In this way, the protrusions 94 function similarly to the compression limiter and spring portion described above. Furthermore, all three exposed edges of each protrusion 94 engage with the conductor in the crimped state to improve the reliability of the electrical connection.

[0034] The crimped portion 90 also includes a first sidewall 97 and a second sidewall 98, wherein the height of the first sidewall is greater than the height of the second sidewall. The first sidewall 97 is configured to crimp in a folded-back manner, similar to... Figures 4A-4D The first sidewall 46 may include similar features (e.g., undercuts and / or protrusions formed therein). However, in Figure 6A and6B In one embodiment, the second sidewall 98 is configured to remain in the vertical position shown in the crimped state of the terminal to hold the conductor shown. As shown, a first portion of the first sidewall 97 includes a height sufficient to extend to the second sidewall 98 in the crimped state, thereby engaging the conductor over its entire width.

[0035] The foregoing has illustrated some possibilities for implementing the invention. Many other embodiments are possible within the scope and spirit of the invention. Therefore, the foregoing description is intended to be illustrative rather than restrictive, and the scope of the invention is given by the appended claims in their entirety. For example, it should also be understood that embodiments of this disclosure may include any combination of the features described above, such as various combinations of compression limiters and spring arrangements, and are not limited to the exemplary arrangements illustrated in the figures.

Claims

1. An electrical terminal (30) for mating with the exposed conductor (12) of a flat flexible cable (10), comprising: Electrical contact (32); as well as A crimped portion (36, 40, 80, 90), extending from the electrical contact (32) in the longitudinal direction of the electrical terminal (30) to terminate the conductor (12) of the flat flexible cable (10), the crimped portion (36, 40, 80, 90) comprising: The base (44) defines at least one protrusion extending therefrom; A first sidewall extends from the base (44) and includes a first portion (56) attached to the base (44) and a second portion (57) attached to the first portion (56) at an end opposite to the base (44). A second sidewall, defined from the base (44), the base (44) and the first and second sidewalls defining an opening (70) configured to receive the conductor (12), and A first cantilever spring and a second cantilever spring extend directly from the first sidewall or the second sidewall in a direction transverse to the longitudinal direction of the electrical terminal. Each of the first and second cantilever springs has a bent fixed end attached to one of the first or second sidewalls along the longitudinal direction of the electrical terminal and a free end opposite to the fixed end in a direction transverse to the longitudinal direction of the electrical terminal. In the crimped state of the electrical terminal (30), the first portion (56) of the first sidewall is folded into the opening (70) to crimp the conductor (12) into the opening (70) and abut against the protrusion, and the second portion (57) of the first sidewall is folded to overlap with the side of the first portion (56) opposite to the conductor (12).

2. The electrical terminal (30) of claim 1, wherein the second sidewall (48) comprises a first portion and a second portion opposite to the first and second portions (56, 57) of the first sidewall (46), wherein in the crimped state, the first portion of the second sidewall (48) is folded into the opening (70), and the second portion of the second sidewall (48) is folded in a direction opposite to the first portion of the second sidewall (48) to overlap with the first portion of the second sidewall (48).

3. The electrical terminal (30) as claimed in claim 1, wherein a first recess (72) is formed in the side of the first sidewall (46) opposite to the opening (70) and generally between the first portion (56) and the second portion (57), the first recess (72) extending along the length of the first sidewall (46) in the longitudinal direction of the electrical terminal (30).

4. The electrical terminal (30) as claimed in claim 3 further includes a second recess (73) formed in the end of the first sidewall (46) and extending in the first sidewall (46) to a predetermined depth in the longitudinal direction of the electrical terminal (30), wherein the first recess (72) extends into the second recess (73).

5. The electrical terminal (30) as claimed in claim 1, wherein the protrusion extends along the base (44) in the longitudinal direction of the electrical terminal (30).

6. The electrical terminal (30) as claimed in claim 5, wherein the protrusion comprises: First and second end protrusions; A central protrusion (66) is arranged between the first and second end protrusions. The first cantilever spring is arranged between the first end protrusion and the central protrusion (66), and the second cantilever spring is arranged between the second end protrusion and the central protrusion (66).

7. The electrical terminal (30) of claim 5 further includes first and second holes (96) formed through the base (44), wherein the first cantilever spring and the second cantilever spring extend into a corresponding one of the first and second holes (96).

8. A cable assembly comprising: A flat flexible cable (10) includes a plurality of conductors (12) embedded within an insulating material (14), wherein a portion of each of the conductors (12) is exposed via an opening (21, 23, 25) selectively formed in the insulating material (14); as well as A plurality of conductive electrical terminals (30), each of the electrical terminals (30) having a crimp portion (36, 40, 80, 90) that at least partially engages with the opening (21, 23, 25) in the insulating material (14) and receives an exposed portion of a corresponding conductor (12), the crimp portion (36, 40, 80, 90) comprising: The base (44) defines at least one protrusion extending therefrom; A first sidewall extends from the base (44) and includes a first portion (56) attached to the base (44) and a second portion (57) extending from the first portion (56) at an end opposite to the base (44). A second sidewall, defined from the base (44), and the base (44) and the first and second sidewalls define an opening (70) of the crimped portion (36, 40, 80, 90) configured to receive the conductor (12), and A first cantilever spring and a second cantilever spring extend directly from the first sidewall or the second sidewall in a direction transverse to the longitudinal direction of the electrical terminal. Each of the first and second cantilever springs has a bent fixed end attached to one of the first or second sidewalls along the longitudinal direction of the electrical terminal and a free end opposite to the fixed end in a direction transverse to the longitudinal direction of the electrical terminal. In the crimped state of the electrical terminal (30), the first portion (56) of the first sidewall is folded into the opening (70) of the crimping portion (36, 40, 80, 90) to crimp the conductor (12) into the opening (70) of the crimping portion (36, 40, 80, 90) and abut against the protrusion, and the second portion (57) of the first sidewall is folded in the direction opposite to the first portion (56) to fold with the first portion (56).

9. The cable assembly of claim 8, wherein the second sidewall (48) comprises a first portion and a second portion opposite to the first and second portions (56, 57) of the first sidewall (46), wherein in the crimped state, the first portion of the second sidewall (48) is folded in a first direction relative to the base (44) and folded into the opening (70) of the crimped portion (36, 40, 80, 90), and the second portion of the second sidewall (48) is folded in a direction opposite to the first direction to overlap with the first portion of the second sidewall (48).

10. The cable assembly of claim 8, wherein a first recess (72) is formed in the first sidewall (46) on the side opposite to the opening of the crimped portion (36, 40, 80, 90) and generally between the first portion (56) and the second portion (57), the first recess (72) extending along the length of the first sidewall (46) in the longitudinal direction of the electrical terminal (30).

11. The cable assembly of claim 10, further comprising a second recess (73) formed in the end of the first sidewall (46) and extending in the longitudinal direction of the electrical terminal (30) into the first sidewall (46) to a predetermined depth, wherein the first recess (72) extends into the second recess (73).

12. The cable assembly of claim 8, wherein the protrusion comprises: First and second end protrusions; A central protrusion (66) is arranged between the first and second end protrusions. The first cantilever spring is arranged between the first end protrusion and the central protrusion (66), and the second cantilever spring is arranged between the second end protrusion and the central protrusion (66).

13. The cable assembly of claim 8, further comprising first and second holes (96) formed through the base (44), wherein the first cantilever spring and the second cantilever spring extend into a respective one of the first and second holes (96).

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