Patent Publication Number: US-9843123-B1

Title: Electrical connector with terminal position assurance clip

Description:
BACKGROUND OF THE INVENTION 
     The subject matter herein relates generally to electrical connectors that have terminal position assurance clips. 
     Some electrical connectors include conductive contacts, such as pin contacts, that are retained in the connectors using retention features, such as latches. To prevent unintended movement of the retention features which may allow the contacts to be pulled or pushed out of the connectors, some electrical connectors include terminal position assurance (TPA) devices. The TPA devices are configured to block movement of the retention features that would allow the retention features to disengage the contacts. Some TPA devices are inserted over distal ends of the contacts and have narrow openings through which the contacts extend. The contacts are guided through the narrow openings by guidance features, such as ramps, bumps, and guide posts, in the TPA device and/or in a contact retention portion of the connector. 
     There is a current trend of increasing signal density in connectors by increasing the amount of contacts per a given area of the connector. To increase the signal density, many connectors employ smaller contacts and reduce the size of the components of the connectors in proportion to the contacts. Thus, to decrease the size of the electrical connectors that have TPA device described above, the retention features and the guidance features that retain and guide the contacts, respectively, are scaled down. Many of the retention and guidance features are relatively complex to design tooling for and to manufacture already, and minimizing the size of these features adds to the complexity as well as causes additional issues. For example, at least some of the retention features and guidance features may be molded using metal molds. Decreasing the size of the features requires finer metal walls of the molds that define the features. In order to meet the size requirements, some of the metal walls may be so fine that the walls are prone to bending or breaking when the mold is injected with hot filler material, which ruins or at least damages the resulting product. In another example, it is recognized that the retention features and the guidance features must have some resiliency in order to absorb impact forces from the contacts, such as when the contacts are being loaded into the connector or when the contacts are being pushed or pulled by a mating connector. By decreasing the size of the connectors to increase signal density, the retention features and the guidance features may be reduced to a size such that the features lack the required strength to retain and/or guide the contacts. For example, if the guide posts are small and thin enough, the guide posts may bend upon impact from a contact and not provide the desired guidance for the contact. Thus, by reducing the size of the electrical connectors, known retention and guidance features, such as ramps, bumps, and guide posts, may become exceedingly difficult, complex, and/or expensive to produce and may also fail to provide the desired levels of retention and guidance for the contacts. 
     A need remains for an electrical connector having a TPA device that simplifies the retention and guidance features in order to provide for reliable retention and guidance in smaller-sized, higher signal density connectors. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one embodiment, an electrical connector is provided that includes a housing, a terminal retention (TR) block, and a terminal position assurance (TPA) clip. The housing has a mating end and a terminating end. The housing defines a cavity open at the mating end. The TR block is mounted to the housing within the cavity. The TR block defines multiple channels configured to receive contacts therein. The channels extend between a proximal end and a distal end of the TR block. The channels include deflectable retention latches configured to engage the contacts to retain the contacts in the channels. The TPA clip is mounted to the distal end of the TR block within the cavity of the housing. The TPA clip is configured to block deflection of the retention latches to lock the contacts in the channels. The TPA clip has slots that align with the channels of the TR block and receive distal tips of the contacts therethrough. The slots have tapered lead-ins configured to guide the distal tips of the contacts from the channels into the slots. 
     In another embodiment, an electrical connector is provided that includes a housing, a terminal retention (TR) block, multiple contacts, and a terminal position assurance (TPA) clip. The housing has a mating end and a terminating end. The housing defines a cavity open at the mating end. The TR block is mounted to the housing within the cavity. The TR block defines multiple channels extending between a proximal end and a distal end of the TR block. The channels each include a deflectable retention latch therein. The contacts are disposed within corresponding channels of the TR block. Each contact engages and is retained in the respective channel by a corresponding one of the retention latches. The TPA clip is mounted to the distal end of the TR block within the cavity of the housing. The TPA clip is configured to block deflection of the retention latches to lock the contacts in the channels. The TPA clip has slots that align with the channels of the TR block and receive distal tips of the contacts therethrough. The slots have tapered lead-ins configured to guide the distal tips of the contacts from the channels into narrow portions of the slots. The tapered lead-ins are conical and provide 360 degree guidance for the distal tips into the narrow portions of the slots. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an electrical connector in accordance with an embodiment. 
         FIG. 2  is an exploded perspective view of the electrical connector according to an embodiment. 
         FIG. 3  is a cross-section of the electrical connector according to an exemplary embodiment. 
         FIGS. 4A-4C  show cross-sectional views of the electrical connector at various stages of assembly according to an embodiment. 
         FIG. 5  is a close-up cross-sectional perspective view of a portion of the electrical connector showing a TPA clip and a TR block according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a perspective view of an electrical connector  100  in accordance with an embodiment. The electrical connector  100  includes a housing  102  that defines a cavity  104 . The housing  102  has a mating end  106  and a terminating end  108 . The mating end  106  includes an opening  110  to the cavity  104 . The mating end  106  is configured to interface with a mating connector (not shown) to mate with the mating connector and provide a signal path between the connector  100  and the mating connector. The mating connector may be a bulkhead connector. In the illustrated embodiment, a cable  112  extends from the terminating end  108  of the housing  102 . The cable  112  includes one or more conductive wires. The connector  100  may be configured to be mounted directly to a device, such as a transmission or an engine of a vehicle. In alternative embodiments, instead of terminating to a cable, the electrical connector  100  may be mounted directly to a printed circuit board. For example, the connector  100  may be a right angle connector such that a plane of the mating end  106  is perpendicular to a top surface of a printed circuit board to which the connector is mounted or may be a vertical connector such that the plane of the mating end  106  is parallel to the top surface of the circuit board. 
     Within the cavity  104 , the electrical connector  100  includes multiple contacts  114 . The contacts  114  are shown as pin contacts. The pin contacts  114  are configured to be received in corresponding openings of socket contacts of the mating connector. The contacts  114  are not limited to being pin contacts. For example, the contacts  114  may be socket contacts configured to receive pins of a mating connector. The contacts  114  may be deflectable beam-style contacts in another embodiment. The contacts  114  may be configured to convey electrical and/or optical signals. The contacts  114  may be referred to as terminals. The electrical connector  100  further includes a terminal position assurance (TPA) clip  116  within the cavity  104 . The TPA clip  116  includes multiple slots  118 . The contacts  114  extend through the slots  118  and beyond the TPA clip  116  into the cavity  104 . As described below, the TPA clip  116  is configured to provide a secondary retention mechanism that locks the contacts  114  in a fixed position relative to the housing  102 . 
     Optionally, the electrical connector  100  further includes a cable cover  120 . The cable cover  120  surrounds and protects the interface between the cable  112  and the housing  102 . For example, the cable cover  120  may provide strain relief and may block contaminants (for example, liquid, dirt, dust, sand, etc.) from entering the cable  112  and/or the housing  102  at the interface therebetween. Optionally, the electrical connector  100  includes a compressive seal  122 . The compressive seal  122  extends around a perimeter of the housing  102  proximate to the terminating end  108 . The compressive seal  122  is positioned against a flange  124  of the housing  102 . The compressive seal  122  engages the mating bulkhead connector when mated to the electrical connector  100 . The compressive seal  122  at least partially compresses and seals the interface between the mating bulkhead connector and the connector  100 , preventing the passage of contaminants therethrough. In another embodiment, the compressive seal  122  or another seal may be configured to seal to a panel of a device, such as the cover of a transmission, in order to prevent contaminants from passing through the interface between the panel and the connector  100 . Thus, the electrical connector  100  may include one or more sealing and strain relief components. The electrical connector  100  may be used in relatively harsh environments for signal communication, such as with commercial vehicles for example, where the connector  100  is exposed to vibration and various contaminants. 
       FIG. 2  is an exploded perspective view of the electrical connector  100  according to an embodiment. In addition to the TPA clip  116  and the contacts  114 , the housing  102  also includes a terminal retention (TR) block  126  mounted to the housing  102  and held within the cavity  104  (shown in  FIG. 1 ). The TR block  126  includes a proximal end  128  and a distal end  130 . The proximal end  128  is more proximate to the terminating end  108  of the housing  102  than the distal end  130 . Likewise, the distal end  130  is more proximate to the mating end  106  of the housing  102  than the proximal end  128  (when the TR block  126  is held within the cavity  104 ). The TR block  126  defines multiple channels  132  that extend between the proximal end  128  and the distal end  130 . The channels  132  are configured to receive the contacts  114  therein. For example, each channel  132  may be configured to receive one contact  114 . The TR block  126  may be formed of a dielectric material, such as a thermoplastic. The TR block  126  may be electrically insulative. Optionally, the TR block  126  may be formed by a molding process. 
     The TPA clip  116  is configured to be mounted to the distal end  130  of the TR block  126  within the housing  102 . The TPA clip  116  includes a loading end  133  and an opposite forward end  134 . The loading end  133  faces the distal end  130  of the TR block  126 . The forward end  134  faces outward, toward the opening  110  (shown in  FIG. 1 ) at the mating end  106  of the housing  102  when the TPA clip  116  is within the cavity  104  ( FIG. 1 ). The TPA clip  116  may be formed of a dielectric material, such as a thermoplastic. The TPA clip  116  may be formed by a molding process. 
     In an embodiment, the TPA clip  116  is mounted to the TR block  126  via mounting latches  136  on the TPA clip  116 . In the illustrated embodiment, the mounting latches  136  are located on a first side  138  and an opposite second side  140  of the TPA clip  116 . The mounting latches  136  are configured to engage catches  142  along a first side  144  and a second side  146  of the TR block  126  to retain the TPA clip  116  to the TR block  126 . The mounting latches  136  may be releasable to remove the TPA clip  116  from the TR block  126  when desired. In the illustrated embodiment, the TR block  126  further includes alignment posts  148  that extend from the distal end  130 . The alignment posts  148  are configured to be received in corresponding sleeves  150  of the TPA clip  116  as the TPA clip  116  is moved towards the TR block  126  to align the TPA clip  116  and the TR block  126  with one another. Optionally, the alignment posts  148  and the sleeves  150  are located at corners of the respective TR block  126  and TPA clip  116 . Although not shown in  FIG. 2 , when the TPA clip  116  is aligned with the TR block  126 , the slots  118  (shown in  FIG. 1 ) align with the channels  132  of the TR block  126 , such that the channels  132  are fluidly coupled to the slots  118 . The term “fluidly coupled” means that a fluid, such as air, in the channel  132  would be permitted to flow into the corresponding slot  118 , and vice-versa, because the channel  132  and the slot  118  are adjacent to each other and have openings that are aligned with each other. 
     One contact  114  is shown in  FIG. 2 . The contact  114  is a pin contact  114 . The contact  114  has a pin segment  152  at a front end  158  of the contact  114 . The pin segment  152  extends from a base segment  154  at a rear end  160  of the contact  114  to a distal tip  155  at the front end  158 . As used herein, relative or spatial terms such as “top,” “bottom,” “left,” “right,” “front,” and “rear” are only used to distinguish the referenced elements and do not necessarily require particular positions or orientations in the electrical connector  100  or in the surrounding environment of the electrical connector  100 . The base segment  154  is configured to terminate to a wire (not shown) that extends from the rear end  160  of the contact  114 . The base segment  154  has a larger diameter than the pin segment  152 . For example, in an embodiment, the base segment  154  is 1.5 mm in diameter, and the pin segment  152  is 1.0 mm in diameter. The base segment  154  includes a bead  156  that extends at least partially around a perimeter of the base segment  154 . The diameter of the bead  156  is greater than the diameter of the base segment  154 . The bead  156  is used to retain the contact  114  in one of the respective channels  132  of the TR block  126 . In an embodiment, the contact  114  is formed of a conductive material, such as copper, silver, or one or more other metals. Optionally, the contact  114  may be stamped and formed from a panel of sheet metal. 
     In the illustrated embodiment, the electrical connector  100  further includes a wire seal  162 . The wire seal  162  abuts or is at least proximate to the proximal end  128  of the TR block  126 . The wire seal  162  is configured to surround and extend between the wires (not shown) connected to the contacts  114 . The wire seal  162  may be at least partially compressive and seals around the wires to prevent the transmission of contaminants, such as liquids, dirt, dust, and sand, therethrough. For example, when the connector  100  is mated to a mating connector, the wire seal  162  may prevent contaminants from entering the cavity  104  (shown in  FIG. 1 ) through openings at the terminating end  108  of the housing  102  (where the cable  112  shown in  FIG. 1  extends from the housing  102 ). The cable  112  may include a plurality of the wires grouped within an outer jacket. The optional cable cover  120  may be formed by the releasable coupling of a first shell  164  and a second shell  166 . 
       FIG. 3  is a cross-section of the electrical connector  100  according to an exemplary embodiment. In  FIG. 3 , a portion of the housing  102  at the mating end  106  is not shown. The electrical connector  100  also does not show any of the contacts  114  or the cable  112  (both shown in  FIG. 1 ). The cross-section in  FIG. 3  extends across a row of channels  132  in the TR block  126 . The TR block  126  in the illustrated embodiment includes four channels  132  in the row. The channels  132  are separated and divided from nearest (or adjacent) channels  132  by interior walls  170 . 
     The channels  132  include deflectable retention latches  172  therein. The retention latches  172  extend into the channels  132  from the interior walls  170 . The retention latches  172  are configured to engage the contacts  114  (shown in  FIG. 2 ) in the channels  132  to retain the contacts  114  in the channels  132 . In an embodiment, each channel  132  includes one retention latch  172 . In an alternative embodiment, at least some of the channels  132  may include more than one retention latch  172 . The retention latches  172  are cantilevered beams that have a fixed end  174  and a free end  176 . The fixed end  174  is directly secured to the interior wall  170 , unlike the free end  176 . The fixed end  174  is located more proximate to the proximal end  128  of the TR block  126  than the free end  176 . The free end  176  of each retention latch  172  is resiliently deflectable along an arc from the natural resting position of the latch  172  in a direction towards the interior wall  170  from which the latch  172  extends. The resilience of the retention latch  172  (i.e., the bias of the free end  176  of the latch  172  to the natural resting position thereof) generates a retention force between the latch  172  and the contact  114  within the channel  132 . The retention force pushes the contact  114  towards the interior wall  170  opposite to the latch  172 . 
     The retention latches  172  each include a ramp  178  proximate to the free end  176 . The thickness of the ramp  178  increases with distance along the latch  172  towards the free end  176 . The ramp  178  is configured to engage the contact  114  (shown in  FIG. 2 ) as the contact  114  is loaded into the channel  132 . For example, as the contact  114  enters the channel  132 , the contact  114  engages and moves along the ramp  178 , and the retention latch  178  at least partially deflects away from the contact  114  to allow the contact  114  to be moved farther into the channel  132 . The increasing thickness of the ramp  178  causes the retention latch  172  to deflect an increasing distance along the arc towards the interior wall  170  as the contact  114  moves along the ramp  178 . A distal edge  180  of the ramp  178  forms a catch  182  that is configured to be received behind a shoulder or bead of the contact  114  once the contact  114  is fully loaded in the channel  132  to lock and retain the contact  114  in the channel  132 . For example, the catch  182  engages the shoulder or bead to prevent backward movement of the contact  114  towards the proximal end  128  of the TR block  126 . 
     In the illustrated embodiment, each channel  132  also includes a protuberance  184 . Each protuberance  184  extends into the respective channel  132  from an interior wall  170  of the channel  132 . The protuberance  184  may be located along the interior wall  170  across from the retention latch  172 , such as directly across from a front side  186  of the latch  172 . The ramp  178  extends along the front side  186  of the latch  172 . The protuberance  184  may be a bump, a bulge, or another protrusion. In an embodiment, the retention forces applied on the contacts  114  (shown in  FIG. 2 ) by the retention latches  172  is directed towards the protuberances  184  such that the latches  172  force the contacts  114  into engagement with the protuberances  184 . The protuberances  184  provide retention for the contacts  114  due to interference or friction at the engagement interfaces between the protuberances  184  and the contacts  114 . Thus, the protuberances  184  support retention of the contacts  114 . In addition, the protuberances  184  provide guidance for the contacts  114  as the contacts  114  are advanced into the channels  132  because the protuberances  184  force the contacts  114  radially inward and reduce the likelihood of the contacts  114  stubbing against the interior walls  170  of the channels  132 . 
     In an embodiment, the channels  132  do not include any retention features or guide features distal to the retention latches  172  and the protuberances  184  (for example, at or proximate to the distal end  130  of the TR block  126 ). For example, the channels  132  may not taper towards the distal end  130 . Also, the channels  132  do not include built-in guide posts or ramps at the distal end  130 , which is unlike some known electrical connectors that include TPA devices through which the contacts extend to enter a cavity of the connector. Since the channels  132  do not include many of the complex and small features present in some known electrical connectors, the TR block  126  (and the electrical connector  100  in general) may be easier and cheaper to produce than the known connectors. In one or more alternative embodiments, however, the TR block  126  may include at least some guide features and/or retention features proximate to the distal end  130 . 
     The TPA clip  116  is mounted to the TR block  126  within the cavity  104  of the housing  102  in  FIG. 3 . The TPA clip  116  is configured to be movable relative to the TR block  126  between a locked position and an unlocked (or staged) position. In  FIG. 3 , the TPA clip  116  is in the unlocked position. In an embodiment, the TR block  126  includes a distal catch  142 A and a proximal catch  142 B on each of the first and second sides  144 ,  146  of the TR block  126 . The distal catches  142 A are located closer to the distal end  130  of the TR block  126  than the proximal catches  142 B. The mounting latches  136  of the TPA clip  116  engage corresponding distal catches  142 A when the TPA clip  116  is in the unlocked position, as shown in  FIG. 3 , to retain the TPA clip  116  in the unlocked position (and prevent the TPA clip  116  from uncoupling from the TR block  126 ). As described further below, as the TPA clip  116  is moved towards the proximal end  128  of the TR block  126  to the locked position, the mounting latches  136  are configured to engage the corresponding proximal catches  142 B to retain the TPA clip  116  in the locked position. An intermediate ledge  188  along the sides  144 ,  146  of the TR block  126  between the distal and proximal catches  142 A,  142 B may be ramped to allow the mounting latches  136  to slide along the ledge  188  and partially deflect as the TPA clip  116  transitions from the unlocked position to the locked position. In an alternative embodiment, the TR block  126  includes only one catch on each side, and the mounting latches of the TPA clip  116  include both distal and proximal latching features to allow for coupling in the locked and unlocked positions. In another alternative embodiment, the TR block  126  includes the mounting latches and the TPA clip  116  includes the catches. 
     The TPA clip  116  includes locking posts  190  that are elongated and extend from the loading end  133  of the TPA clip  116 . The locking posts  190  are located at sides of the slots  118 . The locking posts  190  extend generally parallel to each other towards the TR block  126 . At least tips  192  of the locking posts  190  are received in the channels  132  of the TR block  126  when the TPA clip  116  is in the locked position. Optionally, as shown in the illustrated embodiment, the tips  192  are within the channels  132  even when the TPA clip  116  is in the unlocked position and is farther from the TR block  126 . The locking posts  190  are configured to be wedged between a back side  194  of the retention latches  172  and the interior walls  170  (for example, a back wall) from which the latches  172  extend when the TPA clip  116  is in the locking position. When wedged behind the latches  172 , the locking posts  190  mechanically block the retention latches  172  from deflecting away from the corresponding contacts  114  (shown in  FIG. 2 ) and towards the back interior walls  170 . By prohibiting deflection of the latches  172 , the locking posts  190  reinforce the retention of the contacts  114  in the channels  132 . Thus, the TPA clip  116  provides a secondary lock (to the primary lock provided by the latches  172 ) that retains the contacts  114  in the channels  132 . In addition, the TPA clip  116  is configured to provide position assurance. For example, if one of the contacts  114  is not fully loaded in the respective channel  132 , the retention latch  172  that engages the contact  114  is deflected towards the back interior wall  170  to a position such that a gap  195  defined between the back side  194  of the latch  172  and the wall  170  is too narrow to receive the corresponding locking post  190 . Since the locking post  190  does not fit within the gap  195 , the TPA clip  116  is prohibited from moving all of the way to the locked position, which indicates that at least one of the contacts  114  is not in a fully loaded position. 
     The slots  118  of the TPA clip  116  extend entirely through the TPA clip  116  between the loading end  133  and the forward end  134 . The slots  118  align with the channels  132  of the TR block  126 . Thus, the TPA clip  116  includes four slots  118  shown in  FIG. 3  that align with the row of four channels  132 . The slots  118  are configured to receive the distal tips  155  (shown in  FIG. 2 ) of the contacts  114  ( FIG. 2 ). In an embodiment, the slots  118  include tapered lead-ins  196  at the leading end  133  that are configured to guide the distal tips  155  of the contacts  114  from the channels  132  into the slots  118 . Due to the tapered lead-ins  196 , the slots  118  each have an entrance  198  at the loading end  133  that has a larger diameter than an exit  200  of the slots  118  at the forward end  134 . In an embodiment, the slots  118  each include the tapered lead-in  196  and a narrow portion  202  that extends between the lead-in  196  and the exit  200  at the forward end  134 . The lead-ins  196  are tapered such that a diameter of each lead-in  196  decreases with depth of the slot  118 . For example, the largest diameter of each lead-in  196  is at the entrance  198  along the loading end  133 , and the smallest diameter of the lead-in  196  is at a confluence  204  between the lead-in  196  and the narrow portion  202  of the slot  118 . The narrow portion  202  may have a generally uniform or constant diameter. The diameter of the narrow portion  202  may be the diameter of the confluence  204 , or, in other words, the smallest diameter of the lead-in  196 . Thus, the tapered lead-ins  196  are sloped to guide the distal tips  155  of the contacts  114  from wider-diameter channels  132  of the TR block  126  to narrower-diameter narrow portions  202  of the slots  118  of the TPA clip  116 . The exits  200  of the slots  118  are narrow in order to accurately control the position and orientation of the distal tips  155  of the contacts  114  in the cavity  104  of the housing  102 . Such control may be required for the contacts  114  to accurately and reliably engage the corresponding mating contacts of the mating connector. 
       FIGS. 4A-4C  show cross-section views of the electrical connector  100  at various stages of assembly according to an embodiment. In  FIG. 4A , two contacts  114  are partially loaded in respective channels  132  of the TR block  126 . The two contacts  114  include a first contact  114 A and a second contact  114 B. The TR block  126  is configured for the contacts  114  to be loaded into the channel  132  in a loading direction  210 . The loading direction  210  is from the proximal end  128  towards the distal end  130 . The loading direction  210  is parallel to the channels  132 . As shown in  FIG. 4A , the first contact  114 A is located farther within the respective channel  132  and is closer to a fully loaded position than the second contact  114 B. As described above, the retention latches  172  in the channels  132  are configured to engage and at least partially deflect as the corresponding contacts  114  are loaded into the channels  132 . 
     As shown in  FIG. 4A , the retention latch  172 A in the same channel  132  as the first contact  114 A is in a deflected or biased state. For example, the ramp  178  of the latch  172 A is engaged with the base segment  154  and/or the bead  156  of the contact  114 A. The base segment  154  of the contact  114 A is sandwiched between the protuberance  184  and the latch  172 A, and the latch  172 A is deflected away from the contact  114 A towards the interior wall  170  due to the size of the base segment  154 . The retention latch  172 B in the same channel  132  as the second contact  114 B is not in a deflected or biased position. Since the second contact  114 B is not loaded as far as the first contact  114 A, the latch  172 B engages a transition between the small diameter pin segment  152  and the larger diameter base segment  154 . The term “biased position” refers to the deflection of the latches  172  due to engagement with a side of the base segments  154  of the contacts  114  or with the beads  156  that extend from the base segments  154 . The latch  172 B may be partially deflected due to the engagement with the pin segment  152  or the transition between the pin segment  152  and the base segment  154 , but the latch  172 B is not in the biased position and is not deflected to the same degree as the other retention latch  172 A. Thus, both contacts  114 A,  114 B shown in  FIG. 4A  are partially loaded, but only the latch  172 A that engages the first contact  114 A is in the biased position. 
     In  FIG. 4A , the TPA clip  116  is in the unlocked position. The electrical connector  100  is configured such that the TPA clip  116  is not movable from the unlocked position to the locked position relative to the TR block  126  until the contacts  114  are fully loaded in the respective channels. For example, since the retention latch  172 A is in the biased position, the gap  195  between the back side  194  of the latch  172 A and the interior wall  170  is too narrow to receive the corresponding locking post  190 A of the TPA clip  116 . Thus, if the TPA clip  116  is advanced towards the proximal end  128  of the TR block  126 , the locking post  190 A would strike the end  176  of the latch  172 A and not be able to fit within the gap  195 , which blocks further movement of the TPA clip  116 . Thus, any latch  172  in the biased position blocks the TPA clip  116  from transitioning from the unlocked position to the locked position. 
       FIG. 4B  shows both of the contacts  114 A,  114 B in fully loaded positions within the respective channels  132 , while the TPA clip  116  remains in the unlocked position. To reach the fully loaded position, the contacts  114  are each advanced in the loading direction  210  until the bead  156  is moved beyond the catch  182  of the retention latch  172 . The retention latch  172  in the biased position is biased to move in the direction towards the contact  114 , so when the force applied on the latch  172  by the bead  156  is removed as the bead  156  moves beyond the catch  182 , the latch  172  moves at least partially towards the natural resting position of the latch  172 . The catch  182  may engage an edge of the bead  156  to retain the contact  114  in the channel  132  between the latch  172  and the protuberance  184 . The movement of the latch  172  towards the natural resting position increases the gap  195  between the latch  172  and the interior wall  170  that the latch  172  extends from. Thus, when the contacts  114  are in the fully loaded positions, the gaps  195  are large enough to allow the locking posts  190  of the TPA clip  116  to be received therein, allowing the TPA clip  116  to be moved to the locked position. 
       FIG. 4C  shows the contacts  114 A,  114 B in the fully loaded positions, and the TPA clip  116  is in the locked position. The TPA clip  116  is moved in a locking direction  212  from the unlocked position to the locked position. The locking direction  212  extends from the distal end  130  of the TR block  126  towards the proximal end  128 , and is parallel to the channels  132 . For example, the locking direction  212  may be opposite to the loading direction  210  of the contacts  114 . In the locked position, the locking posts  190  are disposed in the gaps  195  between the back sides  194  of the corresponding retention latches  172  and the interior walls  170 . The locking posts  190  in the gaps  195  mechanically block the retention latches  172  from deflecting away from the contacts  114 . For example, the locking posts  190  form wedges in the gaps  195  that reduce and/or eliminate the space that the latches  172  can deflect into. The TPA clip  116  thus provides a secondary lock because the locking posts  190  support the latches  172 , which provide primary retention of the contacts  114 . Due to the locking posts  190 , the amount of force required to push the contacts  114  out of the fully loaded positions back towards the proximal end  128  of the TR block  126  is greatly increased. As shown in  FIG. 4C , when the TPA clip  116  is in the locked position, the contacts  114  extend through the slots  118  of the TPA clip  116 , and the distal tips  155  of the contacts  114  are disposed beyond the forward end  134  of the TPA clip  116  within the cavity  104  of the housing  102 . 
       FIG. 5  is a close-up cross-sectional perspective view of a portion of the electrical connector  100  showing the TPA clip  116  and the TR block  126  according to an embodiment. In an embodiment, the electrical connector  100  is configured to provide guidance for the contacts  114  (shown in  FIG. 2 ) as the contacts  114  are loaded in the channels  132  of the TR block  126  and through the slots  118  of the TPA clip  116  in 360 degrees. For example, the electrical connector  100  is oriented with respect to a vertical axis  214 , a lateral axis  216 , and a longitudinal axis  218 . The axes  214 - 218  are mutually perpendicular. It is understood that the axes  214 - 218  are not required to have any particular orientation with respect to gravity. The channels  132  are oriented parallel to the vertical axis  214 . Thus, movement of the contacts  114  along the vertical axis  214  is controlled as the contacts  114  are loaded. As the contacts  114  are loaded into the channels  132 , the distal tips  155  (shown in  FIG. 2 ) of the contacts  114  have a tendency to project in various angles along the plane defined by the lateral and longitudinal axes  216 ,  218 . But, the electrical connector  100  is configured to provide 360 degree guidance (for example, along the lateral and longitudinal plane) for the contacts  114  through the channels  132  and into the narrow portions  202  of the slots  118  without stubbing along the way. Two components that may provide such 360 degree guidance are the retention latches  172  on the TR block  126  and the tapered lead-ins  196  on the TPA clip  116 . 
     For example, the latch  172  is across from the protuberance  184  along the lateral axis  216 . The latch  172  and the protuberance  184  engage opposite sides of the corresponding contact  114  (shown in  FIG. 2 ) to control the lateral position of the contact  114  within the channel  132 . Optionally, the ramp  178  of the latch  172  includes a concave trench  220 . Only a portion of the trenches  220  is shown in the cross-sectional view of  FIG. 5 . The corresponding contact  114  is received in the trench  220  as the contact  114  is loaded into the channel  132 , and the concave surface  222  of the trench  220  provides guidance along the longitudinal axis  218  as well as along the lateral axis  216 . Thus, the trench  220  directs the contact  114  longitudinally towards a center of the channel  132  and laterally towards the protuberance  184 . The protuberance  184 , as described above, prohibits the contact  114  from stubbing on the interior wall  170  that the protuberance  184  extends from. 
     In an embodiment, the tapered lead-ins  196  of the slots  118  of the TPA clip  116  are conical and provide 360 degree guidance for the distal tips  155  (shown in  FIG. 2 ) of the contacts  114  ( FIG. 2 ) towards the narrow portions  202  of the slots  118 . The tapered lead-ins  196  are tapered in 360 degrees along the plane defined by the lateral and longitudinal axes  216 ,  218 , such that the lead-ins  196  resemble funnels or cones. Optionally, the entrances  198  of the slots  118  at the loading end  133  of the TPA clip  116  are circular. The confluences  204 , where the lead-ins  196  transition to the narrow portions  202 , may also be circular, and the confluences  204  are concentric with the circular entrances  198 . Due to the conically-shaped lead-ins  196 , as long as the distal tip  155  of each contact  114  is received within the entrance  198 , the lead-in  196  guides the distal tip  155  towards the narrow portion  202 . The entrance  198  may be generally the same size as the channel  132 , such that there is no risk of the distal tip  155  stubbing on the edges of the entrance  198  and not entering the entrance  198 . Upon entering the lead-in  196  of the slot  118 , the distal tip  155  may be displaced from alignment with the narrow portion  202  by a length along the lateral axis  216 , along the longitudinal axis  218 , or along both axes  216 ,  218 . Still, regardless of where the distal tip  155  initially engages the lead-in  196 , the conical surface  224  of the tapered lead-in  196  guides or funnels the distal tip  155  towards and into the narrow portion  202  as the contact  114  is advanced further in the loading direction  210  (shown in  FIG. 4A ). The conical tapered lead-in  196  is configured to provide guidance that reduces (or eliminates) stubbing without the need for additional guiding features on the TR block  126  or the TPA clip  116 . 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. 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 adapt 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 exemplary 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 appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112(f), unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.