Patent Publication Number: US-2023163495-A1

Title: Electrical Terminal For Flat Flexible Cables

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 16/919,981, filed on Jul. 2, 2020, the entire disclosure of which is incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure relates to electrical terminals, and more particularly, to electrical terminals suitable for crimping to conductors of a flat flexible cable. 
     BACKGROUND 
     As understood by those skilled in the art, flat flexible cables (FFCs) or flat flexible circuits are electrical components consisting of at least one conductor (e.g., a metallic foil conductor) embedded within a thin, flexible strip of insulation. Flat flexible cables are gaining popularity across many industries due to advantages offered over their traditional “round wire” counter parts. Specifically, in addition to having a lower profile and lighter weight, FFCs enable the implementation of large circuit pathways with significantly greater ease compared to a 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. 
     The implementation or integration of FFCs into existing wiring environments is not without significant challenges. In an automotive application, by way of example only, an FFC-based wiring harness would be required to mate with perhaps hundreds of existing components, including sub-harnesses and various electronic devices (e.g., lights, sensors, etc.), each having established, and in some cases standardized, connector or interface types. Accordingly, a critical obstacle preventing the implementation of FFCs into these applications includes the need to develop quick, robust, and low resistance termination techniques which enable an FFC to be connectorized for mating with these existing connections. 
     A typical FFC may be realized by applying insulation material to either side of a pre-patterned thin foil conductor, and bonding the sides together via an adhesive to enclose the conductor therein. Current FFC terminals include piercing-style crimp terminals, wherein sharpened tines of a terminal are used to pierce the insulation and adhesive material of the FFC in order to attempt to establish a secure electrical connection with the embedded conductor. However, due in part to the fragile nature of the thin foil conductor material, these types of terminals have several drawbacks, including much higher electrical resistances compared to conventional round wire F-crimps, inconsistent electrical connectivity between the conductor and the terminal, and mechanical unreliability over time in harsh environments. 
     Accordingly, there is a need for improved electrical terminals and accompanying termination techniques for adapting FFCs to these environments. 
     SUMMARY 
     According to an embodiment of the present disclosure, a terminal for mating with an exposed conductor of a flat flexible cable is provided. The terminal includes an electrical contact and a crimping portion extending from the electrical contact in a longitudinal direction of the terminal for crimping to the conductor of the flat flexible cable. The crimping portion comprises a base defining at least one protrusion extending therefrom, and first and second sidewalls extending from the base. The base and sidewalls define an opening configured to receive the conductor of the flat flexible cable therein. The first sidewall includes a first section attached to the base and a second section attached to the first section on an end opposite the base. In a crimped state of the terminal, the first section of the first sidewall is folded into the opening for crimping the conductor within the opening and against the protrusion, and the second section of the first sidewall is folded so as to overlap or oppose a side of the first section opposite the conductor. 
     A cable assembly according to an embodiment of the present disclosure includes a flat flexible cable having a plurality of conductors embedded within an insulation material. A portion of each of the conductors is exposed via openings selectively formed in the insulation material, allowing for a crimping portion of an electrically conductive terminal to engage with the conductor within the opening. The crimping portion of the terminal includes a base defining at least one protrusion extending therefrom, and first and second sidewalls extending from the base. The base and the first and second sidewalls define an opening configured to receive the conductor therein. The first sidewall includes a first section attached to the base and a second section attached to the first section on an end opposite the base. In a crimped state of the terminal, the first section of the first sidewall is folded into the opening for crimping the conductor within the opening and against the protrusion, and the second section of the first sidewall is folded in a direction opposite the first section so as to overlap the first section on a side opposite the conductor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described by way of example with reference to the accompanying figures, of which: 
         FIG.  1    is a top view of an exemplary FFC configured for use with terminals according to embodiments of the present disclosure; 
         FIG.  2    is a perspective view of a plurality of terminals according to embodiments of the present disclosure installed in an exemplary connector body; 
         FIG.  3    is a perspective view of the FFC of  FIG.  1    being mated with the terminals and connector body of  FIG.  2   ; 
         FIG.  4 A  is a perspective view of a crimping portion of a terminal according to a first embodiment of the present disclosure in an uncrimped state; 
         FIG.  4 B  is a partial perspective view of the crimping portion of  FIG.  4 A ; 
         FIG.  4 C  is a front cross-sectional view of the crimping portion of  FIGS.  4 A and  4 B ; 
         FIG.  4 D  is a perspective view of the crimping portion of  FIGS.  4 A- 4 C  in a crimped state; 
         FIG.  4 E  is a front cross-sectional view of the crimping portion of  FIG.  4 D ; 
         FIG.  5    is a perspective view of a crimping portion of a terminal according to a second embodiment of the present disclosure; 
         FIG.  6 A  is a perspective view of a crimping portion of a terminal according to a third embodiment of the present disclosure; and 
         FIG.  6 B  is a front cross-sectional view the crimping portion of  FIG.  6 A . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT(S) 
     Exemplary embodiments of the invention will be described hereinafter in detail with reference to the attached drawings, wherein like reference numerals refer to like elements. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the concept of the disclosure to those skilled in the art. 
     Reliably crimping a terminal onto a thin conductor of an FFC requires a means to address the risks of either failing to make suitable (or any) electrical contact with the conductor, or damaging the conductor via the application of excess pressure. This has proven difficult to achieve, in part due to the thin nature of the conductors of the FFC compared to the tolerances of typical crimp-style terminals. For example, with a thickness of less than a tenth of a millimeter (mm) (e.g., 0.07 mm), crimping height tolerances can easily exceed the thickness of the conductor, which may result in either a complete lack of electrical contact between the terminal and the conductor, or the crushing and destruction of the conductor, despite a proper crimping operation. As will be set forth in greater detail herein, embodiments of the present disclosure aim to address these difficulties, providing crimpable terminals that enable reliable, low-resistance connections to be realized in mass termination or crimping operations. 
     Terminals according to embodiments of the present disclosure may be configured for use with an FFC, such as the exemplary portion of an FFC  10  shown in  FIG.  1   . As illustrated, the FFC  10  generally includes a plurality of conductors  12  embedded within an insulation material  14 . The conductors  12  may comprise metallic foil, such as copper foil on the order of 0.07 mm in thickness, by way of example only, patterned in any desirable configuration. The insulation material  14 , such as a polymer insulation material, may be applied to either side of the conductors  12  via an adhesive material, resulting in an embedded conductor arrangement. The exemplary FFC  10  includes multiple segments  20 , 22 , 24 , each containing a plurality of conductors  12 . Respective windows or openings  21 , 23 , 25  are selectively formed or defined proximate respective ends of the segments  20 , 22 , 24  for exposing the conductors  12 , enabling connectorization thereof utilizing terminals according to embodiments of the present disclosure. Windows or openings may be formed in the insulation material  14  in any desired location in order to expose portions of the conductors  12  for facilitating termination. Additional openings  16  may be provided, and configured to accept complementary features of associated connectors, as will be described in further detail herein. 
     With reference to  FIG.  2   , an exemplary inner housing  26  forming a part of a connector is provided for fixing to the FFC  10  of  FIG.  1   , by way of example only. As shown, the inner housing  26  is pre-fitted with a plurality of conductive terminals  30  according to embodiments of the present disclosure. Each terminal  30  generally includes an electrical contact or mating end  32 , in this case, a female mating end configured to receive a corresponding male terminal for establishing an electrical connection. The mating end  32  may comprise one or more locking features  33  configured to engage with the inner housing  26  for securing the terminal  30  thereto. A rear end  34  of the terminal  30  opposite the mating end  32  may include piercing elements  35 , embodied herein as a pair of sharpened tines. Arranged between the mating end  32  and the rear end  34  is a crimping portion  36  configured to be plastically deformed to crimp onto a conductor arranged therein. 
       FIG.  3    illustrates an intermediate step in a connectorization process of the FFC  10 . As shown, the FFC  10  is placed over a plurality of connectors, including inner housing  26  of  FIG.  2   , as well as two second inner housings  28 . The terminals  30  of each of the connectors receive the exposed conductors  12  within respective crimping portions  36  thereof which extend through the windows  21 , 23 , 25  (see  FIG.  1   ) formed in the insulation material  14  of the FFC  10 . The crimping portions  36  are configured to be crimped onto the conductors  12 , for example, in a mass termination or crimping step wherein the crimping portions  36  of each of the terminals  30  is crimped simultaneously, securing the terminals  30 , and thus the inner housings  26 , 28  to the FFC  10 . The inner housings  26 , 28  may further define strain relief portions  37 , 38  configured to extend through the openings  16  in the FFC  10 , which are used to further secure the inner housings  26 , 28  to the FFC  10 . Likewise, as shown, the piercing elements  35  penetrate the insulation material  14  of the FFC  10 , and may be flattened or otherwise deformed thereafter for further securing the terminal  30  to the FFC  10 . In this way, the piercing elements  35  and the strain relief portions  37 , 38  provide forms of strain relief for the resulting connection, mechanically fixing the position of the FFC  10  relative to the terminals  30 . 
       FIGS.  4 A- 4 E  illustrate an embodiment of a crimping portion  40  of a terminal (e.g., terminal  30  of  FIGS.  2  and  3   ) configured for use with an FFC according to the present disclosure, with a remainder of the terminal not shown. Referring to  FIGS.  4 A- 4 C , in an uncrimped state, the crimping portion  40  comprises a generally U-shaped body  42 , including a base  44  and two generally opposing sidewalls or wings  46 , 48  extending from either side thereof in a direction generally perpendicularly from the base  44 . A contact or conductor receiving opening or space  70  is defined between the sidewalls  46 , 48  and is configured (e.g., sized and shaped) to receive an exposed conductor of an FFC (e.g., conductor  12  shown in  FIGS.  1  and  3   ) therein along an axial direction of the terminal. Each sidewall or wing  46 , 48  may be defined by two sections, as more clearly illustrated in  FIGS.  4 B and  4 C . Specifically, the first sidewall  46  comprises a first section  56  extending from and adjoining the base  44  at a first end thereof, and a second section  57  extending from an end of the first section. The first and second sections  56 , 57  may be uniformly continuous with one another, or may be partially divided. For example, a relief or recess  72 , which may be embodied as a score line, is formed partially through an intermediate portion of the sidewall  46  in a direction transverse to the longitudinal direction of the terminal, wherein the first and second sections  56 , 57  reside on respective sides of the recess  72 . The recess  72  may extend in a longitudinal direction of the terminal and along a length of the entire sidewall  46 . The recess  72  is configured to facilitate bending between each of the first and second sections  56 , 57  during a crimping operation, so that the second section may be more easily “folded back” over the first section, as illustrated in a crimped state of the terminal shown in  FIGS.  4 D and  4 E . This folding may be further enabled by the formation of a second recess or an undercut  73  formed into each longitudinal end of the first sidewall  46  in an area of the recess or relief  72 , such that the recess  72  opens into, or is in communication with, the undercut  73 . The undercut  73  extends generally into the sidewall  46  in an axial or longitudinal direction thereof to a predetermined depth, with a portion of the undercut  73  being formed in each of the first and second sidewall sections  56 , 57 . 
     As shown in  FIG.  4 C , the first and second sections  56 , 57  may each extend in a different direction relative to the base  44 . More specifically, the first section  56  may extend generally perpendicularly from the base  44 , while the second section  57  extends at a non-zero angle from the end of the first section  56  (or a non-normal angle with respect to the base  44 ), and in a direction generally away from a center of the crimping portion  40 . The angled nature of the second section  57  relative to the first second  56  facilitates the crimping or folding of the second section  57  relative to the first section  56  in the desired direction via a force applied in a downward direction onto a top of the second section  57 . As illustrated, the second sidewall  48  comprises first and second sections having features similar to those set forth above with respect to the first sidewall  46 , such as a corresponding relief and/or undercut defined therein, and will not be described in further detail herein. 
     Referring to  FIGS.  4 D and  4 E , the crimping portion  40  is shown in a crimped state, wherein the opposing sidewalls  46 , 48  have been crimped or deformed in the described fold back manner from the orientation shown in  FIGS.  4 A- 4 C . As illustrated, the first and second sections  56 , 57  of the first sidewall  46  having been folded or crimped into a generally parallel orientation with respect to the base  44 , with the first section  56  folded or rotated in a first direction with respect to the base, and the second section  57  folded in a direction opposite the first direction, such that it overlaps the first section  56  in an opposing or abutting manner. The second sidewall  48  is crimped in a similar, albeit directionally opposite manner, to the first sidewall  46 . The sidewalls  46 , 48  may be folded or crimped simultaneously via application of single downward force on the free ends thereof, allowing for faster termination compared to multi-step crimping processes required for other terminal types.  FIG.  4 E  provides an exemplary cross-sectional view of a crimped state of the crimping portion  40 , including a conductor  100  crimped within the receiving space  70  by the sidewalls  46 , 48 . 
     As set forth above, reliably crimping to a thin, foil conductor of an FFC requires a means to address the risks of either failing to make suitable electrical contact with the conductor, or damaging the conductor via the application of excess pressure. Embodiments of the present disclosure address this problem via the introduction of several additional features onto or into the base  44  of the crimping portion  40  to prevent either of the above failures. 
     Still referring to the embodiment of  FIGS.  4 A- 4 E , the crimping portion  40  includes an axially-extending protrusion or protruding structure  60  rising into the receiving opening  70  from the base  44  and/or from lower ends the first or second sidewalls  46 , 48 . In the illustrated embodiment, the protrusion  60  includes a plurality of segments, including a pair of outer compression limiters  64  defined by raised protrusions extending from the base  44  in a vertical direction into the receiving opening  70 . Likewise, a central compression limiter  66  is defined by a protrusion arranged generally between the outer compression limiters  64 . In the exemplary embodiment, each of the compression limiters  64 , 66  comprises an outer curved or rounded profile having an axis of curvature aligned generally parallel with an axial or longitudinal direction of the terminal and/or the conductor to be arranged therein. The outer compression limiters  64  also comprise rounded ends  65  extending in respective axial directions. As shown in  FIG.  4 D , at least a portion of each of the outer compression limiter  64  extends in an axial direction beyond an end of the first and second sidewalls  46 , 48 , ensuring maximum contact area with a conductor crimped within the terminal. 
     Due in part to their curved nature, the compression limiters are configured (i.e., are sized and shaped) so as to compress a conductor under force from the crimped first and second sidewalls in a manner which will prevent damage thereto. Moreover, the added height of the compression limiters ensures that reliable electrical contact is always achieved with the conductor, addressing the above-described tolerance-related issues with crimping solutions of the prior art. Further still, the height of the compression limiters may be selected so as to allow for crimp height and compressive force adjustments for a given application (e.g., for different thicknesses of conductors). 
     Still referring to  FIGS.  4 A- 4 E , the protrusion  60  further comprises protruding spring sections or pushers  68  formed between the outer compression limiters  64  and the central compression limiter  66 . Each spring section  68  may be arranged at least partially within a corresponding aperture  69  formed through the base  44 . The spring sections  68  may each comprise a curved or rounded profile extending into the receiving opening  70  and having an axis of curvature oriented parallel to the axial direction of the terminal. In one embodiment, a radius of curvature of the spring sections  68  generally matches that of the compression limiters  64 , 66 . The spring sections  68  may be taller than the compression limiters  64 , 66 , and thus extend further vertically into the receiving opening or space  70 . The spring sections  68  may be embodied as cantilevered springs, each having a free end and a fixed end attached to or extending from a respective sidewall  46 , 48  (or the base  44 ), for providing additional elasticity. In other embodiments, the springs sections  68  may comprise uniformly supported leaf springs, with each spring section  68  attached at each end thereof to a respective sidewall  46 , 48  (or the base  44 ). 
     The spring sections  68  and the compression limiters  64 , 66  create a generally continuous rounded protrusion  60  extending axially within the receiving opening  70 . However, nominal gaps or voids may be defined through the base between the spring sections  68  and compression limiters  64 , 66 , allowing for their independent motion or deformation. Further, the edges of each spring section  68  extending transverse to the longitudinal direction of the terminal may improve engagement, and thus electrical contact, with a conductor crimped within the terminal. The spring sections  68  are configured (i.e., sized and shaped) so as to ensure an upward pressure is maintained on a conductor crimped within the terminal, further improving electrical contact with an engaged sidewall of the crimping portion  40 . 
       FIGS.  5 ,  6 A and  6 B  illustrate additional embodiments of the present disclosure. These embodiments may comprise features similar to those set forth above with respect to the embodiment of  FIGS.  4 A- 4 D , wherein only relevant distinctions therebetween will be describe herein. For example, the crimping portion  80  according to the embodiment of  FIG.  5    includes a compression limiter  83  defining a single elongated protrusion extending in an axial direction of the terminal. The compression limiter  83  may extend along a base  84  substantially over an entire length of the crimping portion  80  or over a length substantially equal to a length of two sidewalls  85 , 86  configured to be crimped to a conductor arranged within the crimping portion. The compression limiter  83  tapers from a raised center thereof to the base  84  in all directions and defines no planar surfaces. The sidewalls  85 , 86  of the embodiment of  FIG.  5    may comprise features similar to those set forth above with respect to  FIGS.  4 A- 4 E . 
     In the embodiment of a crimping portion  90  shown in  FIGS.  6 A and  6 B , two cantilevered protrusions  94  extend from respective sidewalls and at least partially into respective apertures  96  formed through a base of the crimping portion. Free ends of each protrusion  94  may be bent upwards, or formed linearly upwardly (i.e., project at a non-zero angle relative to the base), so as to extend into the receiving opening of the terminal. In this way, the protrusions  94  function in a similar manner to the above-described compression limiters, as well as the spring portions. Moreover, the three exposed edges of each of the protrusions  94  engage with a conductor in a crimped state for improving the reliability of the electrical connection. 
     The crimping portion  90  further comprises a first sidewall  97  and a second sidewall  98 , wherein the first sidewall comprises a height greater than that of the second sidewall. The first sidewall  97  is configured to be crimped in a fold back manner, similar to the first sidewall  46  of  FIGS.  4 A- 4 D , and may include like features (e.g., an undercut and/or a relief formed therein). However, in the embodiment of  FIGS.  6 A and  6 B , the second sidewall  98  is configured to remain in the illustrated vertical position in a crimped state of the terminal, for retaining the illustrated conductor. As shown a first section of the first sidewall  97  comprises a height sufficient extend to the second sidewall  98  in the crimped state, thus engaging a conductor over its entire width. 
     The foregoing illustrates some of the possibilities for practicing the invention. Many other embodiments are possible within the scope and spirit of the invention. It is, therefore, intended that the foregoing description be regarded as illustrative rather than limiting, and that the scope of the invention is given by the appended claims together with their full range. For example, it should also be understood that embodiments of the present disclosure may include any combination of the above-described features, such as various combinations of compression limiters and spring arrangements, and are not limited to the exemplary arrangements set forth in the figures. 
     Also, the indefinite articles “a” and “an” preceding an element or component of the invention are intended to be nonrestrictive regarding the number of instances, that is, occurrences of the element or component. Therefore “a” or “an” should be read to include one or at least one, and the singular word form of the element or component also includes the plural unless the number is obviously meant to be singular. 
     The term “invention” or “present invention” as used herein is a non-limiting term and is not intended to refer to any single embodiment of the particular invention but encompasses all possible embodiments as described in the application.