Patent Publication Number: US-11394145-B2

Title: Electrical connector

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional application and claims the benefit of U.S. patent application Ser. No. 16/829,184 filed Mar. 25, 2020 which is a divisional application that claimed the benefit of co-pending U.S. patent application Ser. No. 16/354,599 filed Mar. 15, 2019, the entire disclosure of each of which is hereby incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The invention generally relates to an electrical connector, particularly to an electrical connector configured to electrically interconnect a flat cable. 
     BRIEF SUMMARY 
     According to one or more aspects of the present disclosure, an electrical connector assembly includes a housing including a planar first substrate having an electrically conductive first contact region and configured to receive a planar second substrate having an electrically conductive second contact region which defines a ridge protruding from a surface of the second substrate. The housing is configured to align the first contact region with the second contact region. The electrical connector assembly further includes a force application device configured to apply a compressive contact force to the first and second substrates, thereby putting the first contact region in intimate compressive contact with the second contact region. 
     In one or more embodiments of the electrical connector assembly according to the previous paragraph, the ridge is formed on an outer edge of a plated through hole in the second trace within the second contact region wherein a height of the ridge decreases from the outer edge to the plated through hole. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the ridge forms an inverted frustoconical shape. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the second contact region defines a plurality of the plated through holes arranged linearly in the second contact region. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the ridge is formed by a serpentine pattern in the second trace within the second contact region. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the compressive contact force comprises a first compressive contact force and a second compressive contact force in opposition to the first compressive contact force. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the force application device has a first spring member configured to apply the first compressive contact force to the first substrate and a second spring member configured to apply the second compressive contact force to the second substrate. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the first spring member is an arcuate first fixed beam having a first radius of curvature and the second spring member is an arcuate second fixed beam having a second radius of curvature and wherein the first radius of curvature is less than the second radius of curvature. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the first spring member and the second spring member are integrally formed within the force application device. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the electrical connector assembly also includes an actuating member that is moveable from a pre-staged position in which the actuating member is not located intermediate the first spring member and the second spring member to a staged position in which the actuating member is located intermediate the first spring member and the second spring member. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the actuating member is integral with a connector position assurance device that is configured to allow movement of the actuating member from the pre-staged position to the staged position when the housing is received within and fully mated with a corresponding mating connector. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the actuating member is sized, shaped, and arranged such that an increase in the compressive contact force is within a predetermined range regardless of an overall thickness of the first substrate and the second substrate. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the force application device has an open box-like structure that is configured to surround the first substrate and the second substrate. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the force application device is formed of a metallic material and the housing is formed of a polymeric material. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the first contact region is defined by an electrically conductive first trace on the first substrate and the second contact region is defined by an electrically conductive second trace on the second substrate and wherein the second substrate is a printed circuit board. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the second contact region defines a plurality of ridges protruding from a surface of the second substrate. 
     According to one or more aspects of the present disclosure, an electrical connector assembly includes a housing including a planar first substrate having a first contact region is disposed and a shroud configured to receive the housing within. The shroud includes a planar second substrate having a second contact region defining a ridge protruding from a surface of the second substrate. The housing and the shroud are configured to align the first contact region with the second contact region. The electrical connector assembly also includes a force application device applying a compressive contact force to the first and second substrates, thereby putting the first contact region in intimate compressive contact with the second contact region. 
     In one or more embodiments of the electrical connector assembly according to the previous paragraph, the force application device is disposed within the housing. The force application device includes a first spring member configured to apply the first compressive contact force to the first substrate and a second spring member configured to apply the second compressive contact force to the second substrate. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the housing further includes an actuating member that is moveable from a pre-staged position in which the actuating member is not located intermediate the first spring member and the second spring member to a staged position in which the actuating member is located intermediate the first spring member and the second spring member. 
     In one or more embodiments of the electrical connector assembly according to any one of the previous paragraphs, the actuating member is integral with a connector position assurance device that is configured to allow movement of the actuating member from the pre-staged position to the staged position when the housing is received within and fully mated with a corresponding mating connector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described, by way of example with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of an electrical connector according to one embodiment of the invention; 
         FIG. 2  is a perspective cross section view of the electrical connector of  FIG. 1  according to one embodiment of the invention; 
         FIG. 3  is a perspective exploded view of the electrical connector of  FIG. 1  according to one embodiment of the invention; 
         FIG. 4  is a perspective cut away view of the electrical connector of  FIG. 1  according to one embodiment of the invention; 
         FIG. 5  is a perspective view of a flat cable used with the electrical connector assembly of  FIG. 1  according to one embodiment of the invention; 
         FIG. 6  is an exploded perspective view of the flat cable used of  FIG. 5  according to one embodiment of the invention; 
         FIG. 7A  is a perspective top view of stiffening member of the flat cable of  FIG. 5  according to one embodiment of the invention; 
         FIG. 7B  is a perspective bottom view of stiffening member of the flat cable of  FIG. 5  according to one embodiment of the invention; 
         FIG. 8  is a perspective exploded view of the flat cable of  FIG. 5  prior to insertion in the electrical connector of  FIG. 1  according to one embodiment of the invention; 
         FIG. 9  is a perspective view of an assembly of the flat cable of  FIG. 5  with the electrical connector of  FIG. 1  according to one embodiment of the invention; 
         FIG. 10  is a perspective cross section view of the assembly of  FIG. 9  according to one embodiment of the invention; 
         FIG. 11  is a side cross section view of the assembly of  FIG. 9  according to one embodiment of the invention; 
         FIG. 12  is a perspective exploded view of a connector position assurance device including an actuating member prior to insertion in the assembly of  FIG. 9  according to one embodiment of the invention; 
         FIG. 13  is a side cross section view of the assembly of  FIG. 9  with the connector position assurance device assembled to the electrical connector of  FIG. 1  and in a pre-staged position according to one embodiment of the invention; 
         FIG. 14  is a perspective view of the assembly of  FIG. 13  according to one embodiment of the invention; 
         FIG. 15  is a perspective view of the assembly of  FIG. 13  and a printed circuit board including a corresponding mating electrical connector according to one embodiment of the invention; 
         FIG. 16  is a cut away side view of the assembly of  FIG. 13  interconnected with the printed circuit board of  FIG. 15  having the connector position assurance device in the pre-staged position according to one embodiment of the invention; 
         FIG. 17  is a cut away side view of the assembly of  FIG. 13  interconnected with the printed circuit board of  FIG. 15  having the connector position assurance device in the staged position according to one embodiment of the invention; 
         FIG. 18  is an isolated view of a contact region of the printed circuit board of  FIG. 15  according to one embodiment of the invention; and 
         FIG. 19  is an isolated view of a contact region of the printed circuit board of  FIG. 15  according to another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the various described embodiments. However, it will be apparent to one of ordinary skill in the art that the various described embodiments may be practiced without these specific details. In other instances, well-known methods, procedures, components, circuits, and networks have not been described in detail so as not to unnecessarily obscure aspects of the embodiments. 
       FIGS. 1-19  illustrate a non-limiting example of an electrical connector according to one or more embodiments of the invention. As best illustrated in  FIG. 3 , the electrical connector, hereinafter referred to as the connector  10 , includes a housing  12 , a force application device, hereinafter referred to as the spring array  14 , and a retainer  16  that is configured to secure the spring array  14  within the housing  12 . 
     The connector  10  is configured to receive a planar first substrate, in this particular non-limiting example a flat cable  18 , as best shown in  FIGS. 8 and 9 . The flat cable  18  includes a plurality of electrically conductive circuit traces (not shown), each having an exposed first contact region  22 . The flat cable  18  also includes a stiffening member  24  that is attached to the flat cable  18  opposite the first contact regions  22 . 
     The connector  10  and flat cable  18  are configured to be received within a corresponding mating connector  26  attached to a planar second substrate, in this particular non-limiting example a printed circuit board (PCB)  28 , as best shown in  FIGS. 15 and 16 . The PCB  28  may be a component of an electronic controller (not shown) connected to the flat cable  18 . The PCB  28  includes a plurality of electrically conductive second circuit traces  30 , each having a second contact region  32 . When the flat cable  18  and the PCB  28  are received within the connector  10 , the housing  12  is configured to align the first contact regions  22  with the second contact regions  32 . Once the connector  10  is mated with the mating connector  26 , the spring array  14  is configured to apply a compressive contact force to the flat cable  18  and the PCB  28 , thereby putting the first contact regions  22  in intimate compressive contact with the second contact regions  32 . 
     As best illustrated in  FIGS. 12-17 , the connector  10  also includes a connector position assurance (CPA) device  34  that is moveable from a pre-staged position  36  shown in  FIG. 16  to a staged position  38  shown in  FIG. 17 . The CPA device  34  also includes an actuating member  40  that is configured to increase the compressive contact force applied to the flat cable  18  and the PCB  28  via interaction with the spring array  14 . 
     Focusing now on the connector  10 , the housing  12  and the retainer  16  are formed of a dielectric material, e.g. polyamide (PA, also known as nylon), polybutylene terephthalate (PBT), or another engineered polymer. As best shown in  FIG. 2 , the housing  12  defines a cavity  42  extending therethrough in which the spring array  14 , the flat cable  18  and the PCB  28  are received. The spring array  14  is secured within the cavity  42  by latching features on the retainer  16  interfacing with corresponding features defined within the cavity  42 . 
     In the non-limiting example shown in  FIG. 3 , the spring array  14  has an open box shape that is formed by stamping and folding sheet metal, e.g. stainless steel, into the open box shape that surrounds the junction between the flat cable  18  and the PCB  28  when the connector  10  and the mating connector  26  are fully mated. As shown in  FIG. 11 , the bottom surface  44  of the spring array  14  defines a plurality of first spring members, hereinafter referred to as bottom spring members  46 , that are integrally formed with the spring array  14  and are configured to apply a first component  50  of the compressive contact force to the flat cable  18 . The top surface  52  opposite the bottom surface  44  defines a second spring member, hereinafter referred to as the top spring member  48 , that is also integrally formed with the spring array  14  and is configured to apply a second component  54  of the compressive contact force to the PCB  28 . The bottom spring members  46  are arranged such that they contact the flat cable  18  in locations opposite each of the first contact regions  22 . This provides the benefit of providing the first component  50  of the compressive spring force to each of the first contact regions  22 . The top spring member  48  may be a single spring member or may include a plurality of spring members. 
     As shown in  FIG. 16 , the bottom spring members  46  are in direct contact with the flat cable  18  while the top spring member  48  is not in contact with the PCB  28 . Therefore, the second component  54  of the compressive contact force is applied to the PCB  28  by the actuating member  40  which is located intermediate the top spring member  48  and the PCB  28  and in mechanical contact with both the top spring member  48  and the PCB  28  when in the staged position  38  as shown in  FIG. 17 . 
     The open box shape of the spring array  14  is configured such that the compressive contact forces  50 ,  54  applied to the flat cable  18  and PCB  28  are supplied solely by the spring array  14 . The spring array  14  is free floating within the housing  12  such that the housing  12  does not provide any of the compressive contact force to the flat cable  18  or the PCB  28 . The inventors have found that the open sheet metal box of the spring array  14  diminishes a reduction in compressive contact forces  50 ,  54  that may occur over time or with exposure to elevated temperatures, e.g. temperatures exceeding 85° C. due to relaxation when a polymeric element, such as the housing  12 , provides all or a portion of the compressive contact forces  50 ,  54 . 
     As best shown in  FIG. 16 , the bottom spring members  46  each have an arcuate fixed beam portion  56  with a first radius of curvature  58  and the top spring member  48  each have an arcuate fixed beam portion  60  having a second radius of curvature  62 . As can be seen in  FIG. 16 , the first radius of curvature  58  of the bottom spring members  46  is less than the second radius of curvature  62  of the top spring member  48 . This difference in the radii of curvature  58 ,  62  provides two separate benefits. The shorter radius of the first curvature  58  of the bottom spring members  46  forms an apex that causes a smaller contact patch between each bottom spring member  46  and the flat cable  18 , thereby increasing a contact pressure applied between the first contact region and the second contact region  32 . The longer second radius of curvature  62  of the top spring member  48  provides a smaller deviation between an initial insertion force and a peak insertion force as the actuating member  40  is moved from the pre-staged position  36  to the staged position  38  and is inserted between the top spring member  48  and the PCB  28 . The spring array  14  is not an electrical current carrying member of the connector  10 . Therefore, the material choice for the material used to form the spring array  14  may be based on the mechanical properties of the material without any regard to the electrical properties. 
     Alternative embodiments of the connector may not include an actuating member and in these embodiments the top spring member may be in direct contact with the PCB. In these embodiments it may be preferred to have an electrically insulative surface of the PCB in contact with the top spring member or to have an electrical insulative member between the top spring member and the PCB to avoid electrical short circuiting of conductive traces on the PCB. Additionally, alternative embodiments of the connector may include top and bottom spring members that are cantilevered springs, coil springs, elliptical springs, or other types of compression springs. In applications where polymeric creep or relaxation are not a design factor, the spring array may be formed of a polymeric material since the spring array is not a current carrying member and or may not be a separate open box design but may be integrated into the housing. 
     A best shown in  FIG. 12 , the actuating member  40  is a planar member that is integral with the CPA device  34 . The CPA device  34  is formed of a dielectric material, such as PA or PBT. The CPA device  34  is slidably attached to the housing  12  and is configured to ensure that the connector  10  is fully mated with the mating connector  26 . The CPA device  34  is designed such that it may not be moved from the pre-staged position  36  to the staged position  38  until the connector  10  is fully mated with the mating connector  26 . The design and operation of CPA devices for electrical connectors are well known to those having ordinary skill in the art. The thickness of the actuating member  40  is sized such that the second component  54  of the compressive contact force is within a predetermined range regardless of an overall thickness of the flat cable  18  and the PCB  28 . In alternative embodiments, the actuating member may include a plurality of individual fingers aligned with the second contact regions rather than a single planar member. 
     Focusing now on the flat cable  18  as illustrated in  FIG. 5 , the flat cable  18  includes a flexible substrate  64  including the flat first conductive traces, e.g. thin copper strips, encased within an insulative material, such as polyethylene terephthalate (PET). Such a flat cable  18  is typically referred to as a flexible flat cable  18  (FFC) or flexible printed circuit (FPC). As shown in  FIG. 5 , the width of the first conductive traces may be varied to provide different electrical characteristics, e.g. resistance or current capacity. The insulative material is removed from at least one end of the flat cable  18  to expose the first conductive traces, thereby providing the first contact regions  22 . 
     The flat cable  18  also includes a stiffening member  24  that is attached to an end of the flat cable  18  on a side of the flat cable  18  located opposite the first contact regions  22 . The stiffening member  24  may be attached to the flat cable  18  using a pressure bond adhesive (not shown), such as VHB™ double sided adhesive tape manufactured by the 3M Corporation of Minneapolis, Minn. The stiffening member  24  is formed of a dielectric material, such as PA or PBT and includes a planar body portion  68  and a plurality of openings  70  extending through the body portion and configured to allow contact on the surface of the flat cable  18  opposite the first contact regions  22  by the bottom spring members  46 . 
     The stiffening member  24  includes an angled lip  72  on a forward edge of the stiffening member  24  that has a maximum height that is at least equal to a thickness of the flat cable  18 . This angled lip  72  is configured to protect the flat cable  18  as the flat cable  18  and stiffening member  24  are inserted within the cavity  42  and spring array  14 . The stiffening member  24  additionally includes a locking latch  74  configured to engage a strike surface  76  within the cavity  42  of the housing  12 . Without subscribing to any particular theory of operation, as the stiffening member  24  is inserted within the cavity  42 , the angled forward edge of the locking latch  74  causes the planar body to bend upwardly until the rearward edge of the locking latch  74  clears the strike surface  76  and planar body returns to its planar form, thereby engaging the rearward edge of the locking latch  74  with the strike surface  76 . The locking latch  74  and strike surface  76  cooperate to retain the stiffening member  24  within the housing  12 . A rearward edge stiffening member  24  of the stiffening member  24  defines a ridge  78  that is configured to contact a rearward surface  80  of the housing  12  of the electrical connector  10 , thereby positioning the stiffening member  24  within the housing  12 . As best shown in  FIG. 13 , the locking latch  74 , the ridge  78 , and the retainer  16  cooperate to position the first contact regions  22  within the connector  10 . 
     Focusing now on the PCB  28  as shown in  FIGS. 18 and 19 , the PCB  28  includes a circuit board substrate  82  and the plurality of second conductive traces  30  disposed thereon. Exposed ends of the second conductive traces  30  define the second contact regions  32 . The second contact regions  32  define a plurality of ridges  84  protruding from a circuit board substrate surface that are configured to concentrate stress on the first contact regions  22 . Without subscribing to any particular theory of operation, these stress concentrations increase reliability and current carrying capacity of the connection between the first contact regions  22  and the second contact regions  32 . 
     The PCB  28  may use a circuit board substrate  82  that is formed of epoxy or polyimide resins. The resin may be reinforced with a woven glass cloth or other matrix such as chopped fibers. Substrates formed of such materials are typically referred to as FR-4or G-10 type circuit boards. The PCB  28  may alternatively be constructed of ceramic or rigid polymer materials. This listing of acceptable substrate materials is not exhaustive and other materials may also be used successfully. A layer of conductive material, such as a copper-based material is electroplated on at least one major surface of the PCB  28 . The layer of conductive material is then formed to create the second conductive traces  30  and second contact regions  32  typically by using a chemical etching process. 
     In some embodiments of the invention, the plurality of ridges  84  is formed on outer edges of a plurality of plated through holes or vias  86  in the second contact region  32  as shown in  FIG. 18 . Each of the second contact regions  32  may include several interconnected vias  86  arranged linearly. 
     Each via  86  consists of two pads in corresponding positions on different layers of the substrate  82  that are electrically connected by a hole through the board. The hole is made conductive by electroplating. The electroplating is thickest on the outside edge of the pad and is tapered in thickness as it approaches the hole, thereby forming or an “inverted volcano”, i.e. frustoconical, shape. The pad on one or both sides of the PCB  28  is connected to the second conductive traces  30  on the surface of the PCB  28 . The second conductive traces  30  interconnect each of the second contact regions  32  to electrical components on the PCB  28 . The materials and manufacturing techniques used to the form PCBs and vias are well known to those skilled in the art. 
     In other embodiments of the invention, the plurality of ridges  84  is formed by a serpentine pattern  88  in the second conductive traces  30  within the second contact region  32  as shown in  FIG. 19 . 
     The printed circuit board also includes the mating connector  26  which defines a shroud  90  surrounding the second contact region  32  that is configured to receive a forward portion of the housing  12  of the connector  10 . The connector  10  and the mating connector  26  cooperate to align the first contact regions  22  with the second contact regions  32 . 
     While the examples of the connector  10  described herein is configured to connect a flat cable  18  with a PCB  28 , other embodiments of the connector may be envisioned in which the connector is configured to interconnect one flat cable with another flat cable to make an in-line connection. 
     Additionally, while the connector  10  described herein is configured to connect a single flat cable  18  with a PCB  28 , other embodiments of the connector may be envisioned in which the connector is configured to interconnect two flat cables with the PCB; one flat cable connected to each side of the PCB. 
     Further, while the connector  10  described herein includes an actuating member  40  that is integrated with a CPA device  34 . Other embodiments of the invention may be envisioned in which the actuating member is implemented without a CPA device. 
     Accordingly, an electrical connector  10  is presented. The connector provides a zero insertion force (ZIF) connection between the flat cable  18  and the PCB  28 , another flat cable, or any other flat substrate having suitably aligned contact regions while providing a high contact force after the actuating member  40  moved to the staged position  38 . The connector  10  also provides reduced wiping forces between the first and second contact regions  22 ,  32  as the connector  10  and the mating connector  26  are attached to one another. The thickness of the actuating member  40  may be adjusted to accommodate different thicknesses of the flat cable(s), PCB, or other substrate without having to make changes to the housing  12 , retainer  16 , or the spring array  14  of the connector  10 . The actuating member  40  and the spring array  14  cooperate to beneficially provide a uniform compressive contact pressure on each pair of first and second contact regions  22 ,  32 . Additionally, the ridges  84  formed in the second contact regions  32  create stress concentrations that increase the reliability and current carrying capacity of the connection between the first contact regions  22  and the second contact regions  32 . 
     While this invention has been described in terms of the preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to configure a particular situation or material to the teachings of the invention without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments and are by no means limiting and are merely prototypical embodiments. 
     Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the following claims, along with the full scope of equivalents to which such claims are entitled. 
     As used herein, ‘one or more’ includes a function being performed by one element, a function being performed by more than one element, e.g., in a distributed fashion, several functions being performed by one element, several functions being performed by several elements, or any combination of the above. 
     It will also be understood that, although the terms first, second, etc. are, in some instances, used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first contact could be termed a second contact, and, similarly, a second contact could be termed a first contact, without departing from the scope of the various described embodiments. The first contact and the second contact are both contacts, but they are not the same contact. 
     The terminology used in the description of the various described embodiments herein is for the purpose of describing embodiments only and is not intended to be limiting. As used in the description of the various described embodiments and the appended claims, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term “and/or” as used herein refers to and encompasses all possible combinations of one or more of the associated listed items. It will be further understood that the terms “includes,” “including,” “comprises,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     As used herein, the term “if” is, optionally, construed to mean “when” or “upon” or “in response to determining” or “in response to detecting,” depending on the context. Similarly, the phrase “if it is determined” or “if [a stated condition or event] is detected” is, optionally, construed to mean “upon determining” or “in response to determining” or “upon detecting [the stated condition or event]” or “in response to detecting [the stated condition or event],” depending on the context. 
     Additionally, while terms of ordinance or orientation may be used herein these elements should not be limited by these terms. All terms of ordinance or orientation, unless stated otherwise, are used for purposes distinguishing one element from another, and do not denote any particular order, order of operations, direction or orientation unless stated otherwise.