Abstract:
A compression connector for connecting the conductor pads of a flat flexible cable to the conductor pads of a printed circuit board. The connector includes a carrier plate which carries a hardboard, the flexible circuit and an interposer through the use of extending peg portions extending from one side of the plate. The peg portions extend beyond the interposer for receipt within positioning openings of the printed circuit board to position the flexible circuit and interposer for electrical connection to the conductor pads of the printed circuit board. A cage structure is secured to the printed circuit board having a top wall covering the positioning openings as well as the conductor pads of the printed circuit board. An actuator having a tension spring mounted thereon is slidably carried on the opposite side of the carrier plate. The actuator is movable between a first position corresponding to a disengaged position and a second position corresponding to an engaged position. The extending peg portions may be placed in the positioning openings with the actuator in its first position and the actuator can then be moved to its second position, causing the top wall of the cage structure to engage with and compress the spring and thereby provide compression force against the flexible circuit, interposer and conductor pads of the printed circuit board to effect appropriate mechanical and electrical connections.

Description:
FIELD OF THE INVENTION 
   This invention relates generally to a compression connector for connecting a flat flexible circuit to a printed circuit board. 
   BACKGROUND OF THE INVENTION 
   In the field of electronics, there is an increasing need for connections between rigid printed circuit boards and flexible cables such as flat flexible circuits. Since relatively complex circuits are now constructed on flexible materials, their connection to conventional printed circuit boards has become increasingly more important. 
   Such connections have, oftentimes, been effected by soldering or through the use of fastening hardware, such as screws, to facilitate a secure electrical connection. It is desirable to be able to secure alignment for a proper mechanical and electrical connection and to effect such connection without the need to utilize loose hardware which can easily be lost, mishandled or dropped. Even retained hardware requires proper tightening and subsequent loosening to effect proper electrical connection and subsequent disconnection between the conductor pads of the flexible circuit and the conductor pads of the printed circuit board. These tasks require appropriate tools as well as time in order to properly connect and disconnect the mating components. 
   BRIEF SUMMARY OF THE INVENTION 
   An object, therefore, of the invention is to provide an improved connector which does not utilize loose or retained fastening hardware during the connection and disconnection process and which includes alignment means to align the flexible circuit for proper mechanical and electrical connection to the printed circuit board. 
   In an exemplary embodiment of the invention, a new and improved compression connector is shown for mechanically and electrically connecting the conductor pads of a flat flexible circuit to the conductor pads of a complementary printed circuit board. The connector includes a carrier plate having one side to which a flexible circuit is secured through the use of a pair of extending pegs and having an opposite side which slidably carries an actuator. The actuator is slidably carried by the carrier for movement between a first (disengaged) position and a second (engaged) position. A tension spring is securely mounted to the top side of the actuator at its forward end. 
   The printed circuit board includes a pair of positioning openings or holes for receiving the extending pegs and also includes a cage structure having a top wall and side walls, with the top wall positioned above the positioning holes and also above the conductor pads on the printed circuit board. 
   An interposer is positioned against the conductor pads of the flexible circuit and is adapted to extend electrical connection between the conductor pads of the flexible circuit and the conductor pads of the printed circuit board in response to the positioning of the carrier plate with the extending pegs received in the positioning holes, while the actuator is in its first (disengaged) position, and subsequent movement of the actuator to its second (engaged) position. Movement of the actuator to its second position causes the top wall of the cage structure to engage and compress the tension spring which exerts downward force against the conductor pads of the flexible circuit, the conductor terminals of the interposer, and the conductor pads of the printed circuit board. 
   Other objects, features and advantages of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the connector assembly; 
       FIG. 2  is a perspective view showing the carrier plate and actuator assemblies of the connector; 
       FIG. 3  is an exploded perspective view of the connector assembly; 
       FIG. 4  is a top, rotated view of the carrier plate; 
       FIG. 5  is a bottom view of the carrier plate; 
       FIG. 6  is a bottom view of the flexible circuit; 
       FIG. 7  is a top view of the actuator; 
       FIG. 8  is a bottom view of the actuator; 
       FIG. 9  is a partial bottom perspective view showing cooperation of the latch and channel of the actuator with the carrier plate; 
       FIG. 10  is a side view showing the connector assembly before positioning within the cage structure with the actuator in its disengaged position; 
       FIG. 11  is a side view showing the connector assembly after positioning within the cage structure with the actuator in its disengaged position; and 
       FIG. 12  is a side view showing the connector assembly (without the side wall of the cage) with the actuator in its engaged position within the cage structure. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The compression connector assembly  10  is shown generally in  FIG. 1  and also shown in an exploded perspective view in  FIG. 3 . The connector is shown for the connection of the conductor pads  11 , as seen in  FIG. 6 , of a flat flexible circuit  12  to the conductor pads  13  of a printed circuit board  14 , without the use of screws or other loose fasteners, to facilitate a good mechanical and electrical connection. 
   The connector assembly includes a thin, generally flat, rectangular, molded carrier plate  16  which retains the flexible circuit  12  as hereinafter described in a flat, unwrapped orientation parallel to its bottom surface  18  while carrying a slidable actuator  20  on its top surface  22 . The carrier plate, shown also in  FIGS. 4 and 5 , has a forward end  24  and a rearward end  26  which has extending end tabs  27  and includes portions generally designated as a forward portion  28  and a rearward portion  30 . The carrier plate further includes a pair of spaced apart guide pins  32  extending outward from its top surface  22  along a line generally separating the forward portion  28  of the carrier plate from the rearward portion  30  of the carrier plate. 
   Also protruding from the top surface of the carrier plate is a ridge or bar  34  positioned parallel to and central with respect to opposite side edges  36  of the carrier plate and located at its rearward portion in a perpendicular association with the rearward end  26  of the carrier plate. The bar includes a forward stop surface  35  on the portion extending toward the guide pins and a rearward stop surface  37  at its opposite end flush with the rearward end  26  of the carrier plate. The bar interacts with portions of the actuator as hereinafter described. 
   Extending outward from the bottom side of the carrier plate on the forward portion  28  adjacent the side edges are a pair of compression pegs  38  and a positioning tab  39 . The guide pins  32 , bar  34 , compression pegs  38  and positioning tab  39  are all integrally molded as part of the carrier plate from polybutadiene terephthalate. 
   The flexible circuit, as can be seen in  FIG. 6 , is a generally elongated, flat, rectangular strip  12  having conductor pads  11  on one side of a conductor-terminating flared end  42  along with a pair of opposed slots  44  that are used to align and secure the flexible circuit to the carrier plate within the connector assembly. The slots  44  are positioned at opposite sides of the conductor pads with the openings on opposite side edges of the flexible circuit. One of the slots  44  is framed by a short leg  45  which will be positioned adjacent the positioning tab  39  on the carrier plate  16  to assure proper orientation of the flexible circuit in a position for connection to the printed circuit board, i.e., positioned with the conductor pads  11  facing away from the carrier plate  16 . 
   A generally rectangular hardboard  46 , best seen in  FIG. 3 , which also includes a pair of opposed slots  48  is positioned directly against the bottom side  18  of the carrier plate  16  at the forward end  24  thereof. Again, one of the slots  48  is framed by a short leg  49  which cooperates directly with the positioning tab  39  of the carrier plate to assure proper component orientation. The flexible circuit is positioned, and preferably epoxied, against the hardboard. The slots  44  of the flexible circuit are aligned with the slots  48  of the hardboard, with the conductor pads  11  facing away from the hardboard and with the aligned slots receiving the compression pegs  38 . The short leg of the flexible circuit  45  and the short leg of the hardboard  49  are connected and positioned adjacent the positioning tab  39  of the carrier plate. If the short leg of the flexible circuit  45  and short leg of the hardboard  49  are not positioned in proper orientation along the edge  36  having the positioning tab  39 , the positioning tab will prevent the hardboard and connected flexible circuit from coplanar engagement with the bottom side  18  of the carrier plate. Proper orientation is thereby assured by having the conductor pads  11  of the flexible circuit  12  facing outward from the carrier plate  16  for electrical connection with the conductor pads  13  of the printed circuit board  14 , as hereinafter more fully described. 
   A generally rectangular shaped interposer  50  is utilized in the assembly and includes a first side  52  having first conductor terminals  54  that provide a mating area for engagement with the conductor pads  11  of the flexible circuit and a second side  56  including second conductor terminals (not shown) that provide a mating area for establishing electrical connection with the conductor pads  13  of the printed circuit board  14 . The interposer includes a pair of holes  60  in registration with the respective slots  44  formed in the flexible circuit  12  and the slots  48  in the hardboard  46  for also receiving the compression pegs  38 . 
   The compression pegs  38  extend through the respective registered slots and openings to retain the hardboard, flex circuit and the interposer while also providing an extended peg portion extending beyond the interposer and forming a pair of positioning pegs  62  utilized to properly align the guide plate and connected hardboard, flexible circuit and interposer with the printed circuit board during the connection process. The hardboard  46  and the flexible circuit  12  can be positioned against the carrier plate with the respective compression pegs extending through the respective slots of the flexible circuit and the hardboard. The positioning tab  39  assures proper orientation of the hardboard/flexible circuit assembly as earlier described. The interposer  50  can then be placed against the flexible circuit with the compression pegs  38  extending through the holes  60  of the interposer to retain the interposer, flexible circuit and hardboard against the carrier plate. Because the positioning tab  39  does not extend from the bottom end  18  of the carrier plate beyond the thickness of the hardboard, the interposer may be placed over the compression pegs  38  in any orientation without interference from the positioning tab. The positioning pegs  62  are adapted to be received in a pair of receptacle areas or positioning openings  64  formed in the printed circuit board  14  to position the carrier plate and attached hardboard, flexible circuit and interposer for mechanical and electrical connection with the conductor pads  13  of the printed circuit board as later further discussed. 
   The actuator  20 , further shown in  FIGS. 7 and 8 , includes a rearward main portion  66  and a forward extending portion  68  with a top surface  70  and a bottom surface  72  and a front end  74  and a rear end  76 . At the rear end is an actuation bar  78  having an upper ridge  79  and a lower ridge  81 . The actuator is partially retained to the carrier plate by a pair of latches  80 , each forming a channel  82  to receive one of the respective side edges  36  of the carrier plate  16 . The latches extend outward from the bottom side of the actuator as best shown in  FIG. 9 . The lower ridge  81  of the actuation bar includes a pair of notches  83 . 
   The actuator also includes a pair of parallel extending rails or slide portions  84  along the sides of its forward portion which are engaged by an extending lip  86  at the top of each of the respective guide pins  32 . 
   The actuator further includes an elongated channel  88  formed by a pair of molded channel walls  90  extending perpendicular from the bottom surface  72  and running from the actuation bar  78  in a direction toward the front end  74 . The channel walls extend approximately 60% of the distance from the actuation bar toward the front end of the actuator. The bar  34  of the carrier plate is received within the channel  88  for sliding movement between a disengaged or open position and an engaged or closed position. A stop block  91  is molded on the bottom surface of the actuator adjacent the front end in alignment with the elongated channel  88  formed by the channel walls and includes a front stop surface  92  which serves as a stop for the forward stop surface  35  of the bar  34  on the guide plate when the actuator is moved to its fully disengaged position. Additional ribs  93  are provided on the bottom surface of the actuator to provide engagement surfaces that are in contact with the carrier plate and for enhanced structural stability of the actuator. 
   The rearward main portion  66  of the actuator extends outward from the forward extending portion  68  to include a pair of L-shaped hook portions  94  adjacent the downwardly extending latches  80  to provide structural shrouds for the latches. The forward movement of the actuator is stopped when rearward stop surface  37  of the bar  34  engages the lower ridge  81  of the actuation bar  78 . In this position, the extending end tabs  27  of the carrier plate protrude a short distance through the notches  83  in the lower ridge  81  of the actuation bar to provide visual and tactile verification that the actuator is in its fully engaged position. As long as the tabs  27  extend a greater distance than the width of the actuation bar  78 , they will protrude from the notches  83 . When the actuator is moved back in the rearward direction, the bar  34  slides within the channel  88  from the rearward portion of the actuator toward the forward portion until the bar engages the front stop surface  92  of the stop block  90  when the actuator is in its fully disengaged position. The actuator, including all of its integrally molded features, is formed from polycarbonate plus acrylonitrile butadiene styrene. 
   The actuator also carries a stainless steel tension spring  96  on its forward extending portion which can be seen in  FIGS. 1-3 . The spring includes a retaining band  98  with fold-over fastening tabs  100  which are received within a pair of slots  102  formed in the forward extending portion of the actuator. These tabs  100  are folded over against the bottom surface  72  of the actuator to retain the spring in place. The spring further includes a raised central portion having a top spring surface  104 , a forward inclined spring surface  106  and a rearward inclined spring surface  108 . The spring  96  also has a forward extending lip  110 . In an embodiment, for example, where the interposer has sixty (60) contacts, the spring is selected to provide nine (9) lbs of force to effect proper mechanical and electrical connection through the interposer between the contact pads of the flexible circuit and the contact pads of the printed circuit board. 
   The front end  74  of the actuator includes a pair of inclined side portions  111  as shown in  FIG. 2 . The central front end of the actuator in front of the lip  110  of the spring does not have an inclined surface, so as to provide a planar extending, flat surface to support the spring while it is being compressed and extended during the engagement process as later described. 
   As can be seen from  FIG. 1  and  FIG. 3 , the connector assembly includes a stainless steel cage structure  112  secured to the printed circuit board  14  through the use of machine screws  65  which are retained in openings  67  within the printed circuit board. The cage may also be secured to the printed circuit board through the use of either press-fit features and/or solder tails. The cage includes a top wall  114 , and a pair of side walls  116  and may also include a back wall (not shown). The top wall  114  includes a main central portion  118  and a pair of side portions  120 . Gussets are provided adjacent the central portion to provide additional strength for the cage structure. The cage is secured to the printed circuit board so that the top wall of the cage  114  is above the positioning openings  64  and also over the conductor pads  13  on the printed circuit board. Each of the side walls  116  of the cage includes an integrally extending alignment leg  122  extending downward in coplanar relationship with the respective side walls and also includes an outwardly extending mounting tab  124  having a tab opening  126 . The alignment legs  122  are respectively received in alignment holes  128  formed in the printed circuit board  14  which aligns the tab openings  126  with the respective openings  67  in the printed circuit board to facilitate ready securement of the machine screws  65 . 
   Turning now to  FIG. 10 , the connector assembly is shown with the actuator in its fully disengaged or open position, ready to be moved in the direction of arrow A to position the positioning pegs  62  within openings  64  that are provided on the printed circuit board. As further shown in  FIG. 9 , the actuator  20  cooperates with the carrier plate  16  in multiple ways to assure the proper positioning between the two and to permit appropriate movement of the actuator with respect to the carrier plate. The side edges  36  of the carrier plate are received within the respective channels  82  formed on the latches  80  of the actuator. The bottom lip  85  on the latch retains the carrier plate in position with its top surface  22  against the ribs  93  and also against the channel walls  90  extending from the bottom surface  72  of the actuator  20 . 
   When the actuator is in its fully disengaged position, the forward stop surface  35  of the bar  34  abuts against the stop surface  92  of the stop block  91 . With the actuator in this position, a portion of the bar is outside the channel  88  while the balance of the bar continues to be retained within the channel  88 . 
   When the actuator is moved from its disengaged position to an engaged position, the lips of the guide pins  32  move along the rails  84  from the forward end of the actuator toward the rearward end of the actuator until the stop surface  37  of bar  34  engages the lower ridge  81  of the actuation bar  78  at which point the extending end tabs  27  protrude through the notches  83 . 
   With the actuator in its fully disengaged position, the carrier plate may be positioned to be inserted within the cage structure as shown in  FIG. 10 .  FIG. 11  shows the carrier plate having been inserted into the cage structure and, though not shown, the positioning pegs  62  are positioned within the positioning openings  64  formed in the printed circuit board. 
   Once the carrier plate has been properly positioned with the positioning pegs  62  received within the positioning openings  64  as shown in  FIG. 11 , the actuator may be advanced in the direction of arrow A to effect a pressing engagement of the flexible circuit through the interposer to the printed circuit board which will be caused by the compression of the spring by the top wall of the cage as the actuator is moved to the fully engaged position. Prior to advancing the actuator to its fully engaged position, the carrier plate, hard board, flexible circuit, and interposer are merely loosely positioned against the printed circuit board in a position to effect good electrical contact upon exertion of appropriate compression forces downward on the flexible circuit against the interposer and printed circuit board. The inclined side portions  111  of the actuator along with the forward inclined spring surface  106  facilitate a smooth engagement of the actuator and spring with the top wall of the cage structure. The forward extending lip  110  of the spring is not secured to the top surface of the actuator and therefore, upon engagement of the inclined spring surface by the top wall of the cage during insertion of the actuator within the cage structure, the spring is compressed which exerts a downward force against the forward portion of the top surface of the actuator and also moves the front edge of the extending lip  110  toward the front end  74  of the actuator. 
     FIG. 12  shows a side view of the connector assembly without the side wall of the cage structure. This figure shows the positioning pegs received in the positioning openings of the printed circuit board and the actuator fully engaged to its second position to effect proper mechanical and electrical connection of the conductor pads of the flexible circuit through the interposer with the conductor pads of the printed circuit board. As the actuator is moved from the first position shown in  FIG. 11  to the second position shown in  FIG. 12 , the main central portion  118  of the top wall  114  of the cage structure engages the inclined spring surface  106  of the spring  96 , which compresses the spring and moves the forward extending lip  110  forward against the flat top forward surface  74  of the actuator  20 . 
   Once fully engaged and connected, the connector can be readily disengaged and disconnected by movement of the actuator  20  from its second position back to its first position which effects disengagement of the spring  96  from the top wall  114  of the cage and permits the carrier plate to be raised to remove the positioning pegs  62  from the positioning openings  64  of the printed circuit board. The connector can thereby be readily disconnected and, if desired, reconnected to secure good mechanical and electrical connection without the need to utilize loose or retained fastening hardware. 
   While the present invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes and substitutions may be made and equivalents may be used without departing from the spirit and scope of the invention. It is therefore intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.