Patent Publication Number: US-10784595-B2

Title: Power terminal for an electrical connector

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/369,418, filed Aug. 1, 2016, titled “POWER TERMINAL FOR AN ELECTRICAL CONNECTOR”, the subject matter of which is herein incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The subject matter herein relates generally to power terminals for electrical connectors. 
     Power terminals are used to make a power connection between components in high power applications, such as in electric or hybrid electric vehicles between the battery and other components, such as the motor. Often, in such applications, the system includes a high voltage interlock (HVIL) circuit to power down the high power circuit prior to unmating of the power terminals. However, electrical connectors housing the power terminals are not without disadvantages. For instance, some electrical connectors have insufficient overtravel for the power terminals for adequate staggered separation of the HVIL circuit and the high voltage circuit within the same connector. As such, a separate HVIL connector is provided that is unmated prior to unmating the high voltage connector. Such arrangements add cost and complexity to the system. Furthermore, the power terminals, particularly in automotive applications, are subjected to vibration and wear over time. The spring beams making the electrical connection between the power terminals may degrade over time reducing stability of the system. Using higher normal force spring beams to compensate for such stability problems leads to wear of the plating at the mating interface over time. 
     Furthermore, there are many different arrangements for the electrical connectors, such as depending on the particular vehicle or application. For example, different vehicles may require different placement of one or both of the electrical connectors, leading to many different types of electrical connectors for the automotive manufacturers. For example, some manufacturers may require both 90° and 180° applications to accommodate different connector arrangements. Some manufacturers may require a weld tab termination or a crimped wire termination. Tooling an entirely different terminal design for each potential application is expensive. Additionally, maintaining a large part supply for each manufacturer is expensive. 
     A need remains for an electrical connector system having power terminals that are reliable and cost effective. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one embodiment, a power terminal for a high power electrical connector is provided that includes a terminal body having a terminating portion, a mating portion and a base between the terminating portion and the mating portion. The terminating portion is configured to be terminated to a power wire. The mating portion has first and second plates with a mating space therebetween. A spring clip is coupled to the mating portion of the terminal body. The spring clip has an outer shell extending along an exterior of the first and second plates and first and second inner spring plates extending along the first and second plates, respectively, in the mating space. A slot is defined between the first and second inner spring plates configured to receive a tab terminal. The first and second inner spring plates are configured to directly engage and electrically connect the mating portion of the terminal body and the tab terminal. The spring clip includes at least one cantilevered contact spring configured to be spring biased against and electrically connected to the tab terminal. The spring clip includes at least one stabilization contact spring spring biased against and electrically connected to at least one of the first plate or the second plate and configured to be spring biased against and electrically connected to the tab terminal. The stabilization contact spring provides a greater contact normal force against the tab terminal than the cantilevered contact spring. 
     In another embodiment, an electrical connector is provided for mating with and unmating from a high power header connector having a header tab terminal and a high voltage interlock (HVIL) contact. The electrical connector includes a housing having a terminal chamber and an HVIL terminal chamber. A HVIL terminal is received in the terminal chamber. The HVIL terminal has a mating interface configured to be mated to and unmated from the HVIL contact to control a high voltage circuit of the electrical connector. A power terminal is received in the terminal chamber and is configured for electrical connection with the header tab terminal when the electrical connector is mated with the header connector. The power terminal includes a terminal body having a terminating portion, a mating portion and a base between the terminating portion and the mating portion. The terminating portion is configured to be terminated to a power wire. The mating portion has first and second plates with a mating space therebetween. A spring clip is coupled to the mating portion of the terminal body. The spring clip has an outer shell extending along an exterior of the first and second plates and first and second inner spring plates extending along the first and second plates, respectively, in the mating space. A slot is defined between the first and second inner spring plates and extends between a front and a rear. The slot is configured to receive the header tab terminal through the front of the slot. The first and second inner spring plates are configured to directly engage and electrically connect the mating portion of the terminal body and the header tab terminal. The spring clip includes at least one cantilevered contact spring configured to be spring biased against and electrically connected to the header tab terminal. The spring clip includes at least one forward contact spring offset from the at least one cantilevered contact spring toward the front of the slot. The forward contact spring is configured to be spring biased against and electrically connected to the header tab terminal. The forward contact spring is configured to be unmated from the header tab terminal after the cantilevered contact spring is unmated from the header tab terminal when the electrical connector is unmated from the header connector. 
     In a further embodiment, an electrical connector system is provided including a header connector having a header housing holding a header tab terminal. The header tab terminal is oriented for mating in a mating direction along a mating axis. A family of electrical connectors is configured to be terminated to a high power wire and configured for mating with the header connector and the header tab terminal in the mating direction. Each of the family of electrical connectors includes a housing, a power terminal and a spring clip coupled to the power terminal. The housing is one of a right angle housing or an in-line housing. The power terminal is one of a crimp terminal or a weld tab terminal. The spring clip is one of a right-angle spring clip or an in-line spring clip. The housings, power terminals and spring clips are combined in one of a first arrangement, a second arrangement, a third arrangement or a fourth arrangement. In the first arrangement, a crimp barrel of the crimp terminal is crimped to the high power wire and the right angle spring clip is coupled to a mating portion of the crimp terminal. The crimp terminal and the right angle spring clip are loaded into the right angle housing with the high power wire being arranged perpendicular to the mating direction. In the second arrangement, the crimp barrel of the crimp terminal is crimped to the high power wire and the in-line spring clip is coupled to the mating portion of the crimp terminal. The crimp terminal and the in-line spring clip are loaded into the in-line housing with the high power wire being arranged parallel to the mating direction. In the third arrangement, a weld tab of the weld tab terminal is welded to the high power wire and the right angle spring clip is coupled to a mating portion of the weld tab terminal. The mating portion of the weld tab terminal is identical to the mating portion of the crimp terminal. The weld tab terminal and the right angle spring clip are loaded into the right angle housing with the high power wire being arranged perpendicular to the mating direction. In the fourth arrangement, the weld tab of the weld tab terminal is welded to the high power wire and the in-line spring clip is coupled to the mating portion of the weld tab terminal. The weld tab terminal and the in-line spring clip are loaded into the in-line housing with the high power wire being arranged parallel to the mating direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of an electrical connector system formed in accordance with an exemplary embodiment. 
         FIG. 2  is a perspective view of an electrical connector system formed in accordance with an exemplary embodiment including a header connector and an electrical connector mated with the header connector. 
         FIG. 3  is an exploded view of the electrical connector system shown in  FIG. 2  showing the electrical connector poised for mating with the header connector. 
         FIG. 4  is a partial sectional view of the electrical connector system shown in  FIG. 2  showing the electrical connector mated with the header connector. 
         FIG. 5  is a perspective view of an electrical connector system formed in accordance with an exemplary embodiment including a header connector and an electrical connector mated with the header connector. 
         FIG. 6  is an exploded view of the electrical connector system shown in  FIG. 5  showing the electrical connector poised for mating with the header connector. 
         FIG. 7  illustrates a right angle crimp power terminal for the electrical connectors formed in accordance with an exemplary embodiment. 
         FIG. 8  illustrates an in-line crimp power terminal for the electrical connectors formed in accordance with an exemplary embodiment. 
         FIG. 9  illustrates a right angle weld tab power terminal for the electrical connectors formed in accordance with an exemplary embodiment. 
         FIG. 10  illustrates an in-line weld tab power terminal for the electrical connectors formed in accordance with an exemplary embodiment. 
         FIG. 11  illustrates a crimp terminal for the crimp power terminals formed in accordance with an exemplary embodiment. 
         FIG. 12  illustrates a weld tab terminal for the crimp power terminals formed in accordance with an exemplary embodiment. 
         FIG. 13  illustrates a right angle spring clip for the power terminals formed in accordance with an exemplary embodiment. 
         FIG. 14  is a perspective view of an in-line spring clip for the power terminals formed in accordance with an exemplary embodiment. 
         FIG. 15  illustrates one of the power terminal terminated to a header tab terminal. 
         FIG. 16  is a cross-sectional view of the power terminal shown in  FIG. 15 . 
         FIG. 17  is a partial sectional view of the power terminal shown in  FIG. 15 . 
         FIG. 18  is a cross sectional view of the power terminal shown in  FIG. 15 . 
         FIG. 19  is a partial sectional view of the power terminal shown in  FIG. 15 . 
         FIG. 20  is a cross sectional view of the power terminal shown in  FIG. 15 . 
         FIG. 21  is a partial sectional view of the power terminal shown in  FIG. 15 . 
         FIG. 22  is a cross sectional view of the power terminal shown in  FIG. 15 . 
         FIG. 23  illustrates one of the power terminals terminated to the header tab terminal. 
         FIG. 24  is a cross-sectional view of the power terminal shown in  FIG. 23 . 
         FIG. 25  is a partial sectional view of the in-line crimp power terminal. 
         FIG. 26  illustrates the electrical connector and header connector in a mated state. 
         FIG. 27  illustrates the electrical connector and header connector in a partially unmated state. 
         FIG. 28  illustrates the electrical connector and header connector in a partially unmated state. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a schematic illustration of an electrical connector system  100  formed in accordance with an exemplary embodiment. The electrical connector system  100  includes a header connector  102  and an electrical connector  104  configured to be mated with the header connector  102 . In an exemplary embodiment, the electrical connector system  100  is a high power connector system that is used to transfer power between various components as part of a high power circuit  106 . In a particular application, the electrical connector system  100  is a battery system, such as a battery system of a vehicle, such as an electric vehicle or hybrid electric vehicle; however the electrical connector system  100  is not intended to be limited to such battery systems. 
     The electrical connector  104  is configured to be electrically connected to a component  110 , such as through one or more power wires  108 . For example, the electrical connector  104  may be electrically connected to a motor. The header connector  102  is configured to be electrically connected to a component  112 , such as through a direct power bus, bus terminal or power wire. For example, the header connector  102  may be electrically connected to a battery pack, such as through a battery distribution unit, a manual service disconnect or other component. The battery distribution unit may manage the power capacity and functionality of the electrical connector system  100 , such as by measuring current and regulating power distribution of the battery pack. 
     Optionally, the electrical connector  104  may be removably coupled to the header connector  102  to disconnect the high power circuit  106  of one or more of the components, such as the battery pack, the motor or other components of the vehicle, such as for maintenance, repair or for another reason. When mated, one or more power terminals  120  of the electrical connector are terminated to corresponding header terminals  122  of the header connector  102 , such as at mating interfaces thereof. Having a greater number terminals  120 ,  122  increases the current carrying capacity of the system  100 . Optionally, each power terminal  120  may be terminated to a corresponding power wire  108 . 
     In an exemplary embodiment, the header connector  102  and/or the electrical connector  104  may include a high voltage interlock (HVIL) circuit  124  to control the high voltage power circuit  106  during opening and closing or mating and unmating of the connectors  102 ,  104 . For example, both connectors  102 ,  104  may include corresponding HVIL terminals  126 ,  128 . The HVIL circuit  124  may be electrically connected to the component  112  and/or the component  110 . In an exemplary embodiment, the electrical connector  104  utilizes a lever to unmate and/or mate the connectors  102 ,  104 , which may open/close the high voltage circuit and the HVIL circuit during unmating/mating of the connectors  102 ,  104 . The HVIL circuit may be opened first during unmating to shut of the high voltage circuit  106  prior to opening or unmating of the terminals  120 ,  122 , which may reduce the likelihood of damage, such as from arcing. In an exemplary embodiment, the high voltage conducting surfaces of the connectors  102 ,  104  are finger proof and touch safe. 
       FIG. 2  is a perspective view of an electrical connector system  200  formed in accordance with an exemplary embodiment including a header connector  202  and an electrical connector  204  mated with the header connector  202 .  FIG. 3  is an exploded view of the electrical connector system  200  showing the electrical connector  204  poised for mating with the header connector  202 .  FIG. 2  shows the electrical connector  204  in a mated state with the header connector  202 . The electrical connector system  200  is an exemplary embodiment of the electrical connector system  100 . The electrical connector system  200  is a right angle connector system where the connectors  202 ,  204  are mated in a direction perpendicular to the power wires. Components of the electrical connector system  200  may be used in whole or in part with the electrical connector system  100 . Power wires  208  extend from the electrical connector  204  and may extend to a component, such as a motor. The header connector  202  is configured to be mounted to another component, such as a battery pack, a battery distribution unit, or another component. 
     The header connector  202  includes a header housing  210  having a mating end  212 . The header housing  210  holds one or more header terminals  214 . Optionally, the header terminals  214  may be tab terminals having generally planar mating tabs. The header tab terminals  214  may be shrouded to protect the header tab terminals  214 . The header tab terminals  214  may have covers such that the header tab terminals  214  are touch safe. The header housing  210  includes a flange  216  for mounting the header housing  210  to another component. Optionally, the header housing  210  may be mounted horizontally; however, other orientations are possible in alternative embodiments. In an exemplary embodiment, the header housing  210  includes guide features  218  for guiding mating of the electrical connector  204  with the header connector  202 . For example, the guide features  218  may be ribs, posts, slots, keying features or other types of guide features. 
     The electrical connector  204  includes a housing  230  configured to be coupled to the header housing  210 . In an exemplary embodiment, the electrical connector  204  includes a lever  232  rotatably coupled to the housing  230 . The lever  232  is configured to engage the header housing  210 , such as corresponding guide features  218 , to secure the electrical connector  204  to the header connector  202 . Optionally, the lever  232  may include a slot that receives corresponding guide features  218  to control mating and unmating of the electrical connector  204  to the header connector  202 . For example, as the lever  232  is closed the housing  230  may be pulled down onto the header housing  210 . Conversely, as the lever  232  is raised, the housing  230  may be pressed away from and unmated from the header housing  210 . The high power circuit and the HVIL circuit of the electrical connector system  200  may be opened and closed as the electrical connector  204  is unmated from and mated to the header connector  202 . 
     In an exemplary embodiment, the housing  230  is a right angle housing  230  holding the power wires  208  and the power terminals perpendicular to a mating direction along a mating axis  234 . The power wires  208  are at a right angle with respect to the mating axis  234 . Other orientations are possible in alternative embodiments. 
       FIG. 4  is a partial sectional view of the electrical connector system  200  showing the electrical connector  204  mated with the header connector  202 . Power terminals  220  of the electrical connector  204  are mated with and electrically connected to corresponding header tab terminals  214  of the header connector  202 . In an exemplary embodiment, the header connector  202  includes one or more HVIL contacts  226  and the electrical connector  204  includes one or more HVIL terminals  228 . In the mated position, the HVIL terminal  228  is electrically connected to the corresponding HVIL contacts  226 . In the illustrated embodiment, the HVIL terminal  228  is a shunt terminal connected between two HVIL contacts  226 . Other types of HVIL contacts or terminals may be used in alternative embodiments. In an exemplary embodiment, during unmating of the electrical connector  204  from the header connector  202 , the HVIL terminal  228  is unmated from the HVIL contacts  226  prior to the power terminals  220  being unmated from the header tab terminals  214 . 
       FIG. 5  is a perspective view of an electrical connector system  300  formed in accordance with an exemplary embodiment including a header connector  302  and an electrical connector  304  mated with the header connector  302 .  FIG. 6  is an exploded view of the electrical connector system  300  showing the electrical connector  304  poised for mating with the header connector  302 .  FIG. 5  shows the electrical connector  304  in a mated state with the header connector  302 . The electrical connector system  300  is an exemplary embodiment of the electrical connector system  100 . The electrical connector system  300  is a straight-line connector system where the connectors  302 ,  304  are mated in a direction parallel to the power wires. Components of the electrical connector system  300  may be used in whole or in part with the electrical connector system  100 . Power wires  308  extend from the electrical connector  304  and may extend to a component, such as a motor. The header connector  302  is configured to be mounted to another component, such as a battery pack, a battery distribution unit, or another component. Optionally, the header connector  302  may be identical to the header connector  202  (shown in  FIG. 2 ) with the electrical connector  304  be mated in a different direction than the electrical connector  204  (shown in  FIG. 2 ). 
     The header connector  302  includes a header housing  310  having a mating end  312 . The header housing  310  holds one or more header tab terminals  314 . The header tab terminals  314  may be shrouded to protect the header tab terminals  314 . The header tab terminals  314  may have covers such that the header tab terminals  314  are touch safe. The header housing  310  includes a flange  316  for mounting the header housing  310  to another component. Optionally, the header housing  310  may be mounted vertically; however, other orientations are possible in alternative embodiments. In an exemplary embodiment, the header housing  310  includes guide features  318  for guiding mating of the electrical connector  304  with the header connector  302 . For example, the guide features  318  may be ribs, posts, slots, keying features or other types of guide features. 
     The electrical connector  304  includes a housing  330  configured to be coupled to the header housing  310 . In an exemplary embodiment, the electrical connector  304  includes a lever  332  rotatably coupled to the housing  330 . The lever  332  is configured to engage the header housing  310 , such as corresponding guide features  318 , to secure the electrical connector  304  to the header connector  302 . Optionally, the lever  332  may include a slot that receives corresponding guide features  318  to control mating and unmating of the electrical connector  304  to the header connector  302 . For example, as the lever  332  is closed the housing  330  may be pulled down onto the header housing  310 . Conversely, as the lever  332  is raised, the housing  330  may be pressed away from and unmated from the header housing  310 . The high power circuit and the HVIL circuit of the electrical connector system  300  may be opened and closed as the electrical connector  304  is unmated from and mated to the header connector  302 . 
     In an exemplary embodiment, the housing  330  is an in-line housing  330  holding the power wires  308  and the power terminals parallel to a mating direction along a mating axis  334 . Other orientations are possible in alternative embodiments. The power terminals of the electrical connector  304  are mated with and electrically connected to corresponding header tab terminals  314  of the header connector  302 . 
       FIGS. 7-10  illustrate power terminals for the various electrical connectors. For example, the power terminals may be used in the electrical connector  104 ,  204  and/or  304 .  FIG. 7  illustrates a right angle crimp power terminal  400 .  FIG. 8  illustrates an in-line crimp power terminal  402 .  FIG. 9  illustrates a right angle weld tab power terminal  404 .  FIG. 10  illustrates an in-line weld tab power terminal  406 . The power terminals  400 - 406  illustrate a family of power terminals. The power terminals  400 - 406  include various features for interfacing with the power wires and the header tab terminals. For example, the power terminals  400 ,  402  are both configured to be crimped to power wires, whereas the power terminals  404 ,  406  are both configured to be welded to the power wires. The power terminals  400 ,  404  are both configured to be mated at a right angle with the corresponding header tab terminal, whereas the power terminals  402 ,  406  are both configured to be mated in-line with the corresponding header tab terminals. Component parts of the power terminals  400 - 406  are usable in various multiple power terminals  400 - 406  to reduce the overall part count of the family of power terminals. 
       FIG. 11  illustrates a crimp terminal  410  having a terminal body  412  extending between a terminating end and a mating end. The terminal body  412  includes a terminating portion  414  at the terminating end, a mating portion  416  at the mating end and a base  418  between the terminating portion  414  and the mating portion  416 . 
     The crimp terminal  410  extends longitudinally along a longitudinal axis  420 . The power wire is configured to extend away from the terminating portion  414  along the longitudinal axis  420 . The base  418  is positioned between the terminating portion  414  and the mating portion  416  along the longitudinal axis  420 . 
     The terminating portion  414  includes a crimp barrel  422  configured to be crimped to a corresponding power wire. The crimp barrel  422  includes opposed wire grips  424  that are configured to grip the power wire when the crimp barrel  422  is crimped to the power wire. The crimp barrel  422  may have any shape configured to be crimped to the power wire. 
     In an exemplary embodiment, the base  418  wraps entirely around the terminal body  412 . Alternatively, the base  418  may wrap only partially around. For example, the base  418  may include one or more strips wrapping non-continuously around the terminal body  412 . In the illustrated embodiment, the base  418  includes ends  430 ,  432  and sides  434 ,  436 . In the illustrated embodiment, the sides  434 ,  436  are longer than the ends  430 ,  432 . 
     The mating portion  416  includes first and second plates  440 ,  442  opposing each other across a mating space  444 . The crimp terminal  410  is configured to receive the corresponding header tab terminal in the mating space  444 . In an exemplary embodiment, the plates  440 ,  442  each include an interior  446  defining the mating space  444  therebetween and an exterior  448  opposite the interior  446 . The plates  440 ,  442  extend between an inner end  450  and an outer end  452 . The inner end  450  is provided at the base  418  while the outer end  452  is the distal end of the corresponding plates  440 ,  442 . Optionally, the central portion of the plates  440 ,  442  may be recessed towards each other in the mating space  444 . For example, lips  454  may be provided at or near the inner and outer ends  450 ,  452  to recess the central portion inward. In an exemplary embodiment, the plates  440 ,  442  include flanges  456  at the outer end  452 . The flanges  456  may be wider and/or longer than other portions of the plates  440 ,  442 . For example, one or more windows  458  may be defined between corresponding flanges  456 . In an exemplary embodiment, the crimp terminal  410  includes pockets  460  between the base  418  and the inner end  450  of the plates  440 ,  442 . The flanges  456 , the windows  458 , the pockets  460  and/or other components or features may be used to secure other components to the crimp terminal  410 , such as spring clips. 
       FIG. 12  illustrates a weld tab terminal  510  formed in accordance with an exemplary embodiment. The weld tab terminal  510  has a terminal body  512  extending between a terminating end and a mating end. The terminal body  512  includes a terminating portion  514  at the terminating end, a mating portion  516  at the mating end and a base  518  between the terminating portion  514  and the mating portion  516 . 
     The weld tab terminal  510  extends longitudinally along a longitudinal axis  520 . The terminating portion  514  includes a weld tab  522  having a welding surface  524  configured to be welded to a corresponding power wire. The power wire is configured to extend away from the terminating portion  514  along the longitudinal axis  520 , perpendicular to the longitudinal axis  520  or at another angle after being welded thereto. The base  518  is positioned between the terminating portion  514  and the mating portion  516  along the longitudinal axis  520 . 
     In an exemplary embodiment, the base  518  wraps entirely around the terminal body  512 . Alternatively, the base  518  may wrap only partially around. For example, the base  518  may include one or more strips wrapping non-continuously around the terminal body  512 . In the illustrated embodiment, the base  518  includes ends  530 ,  532  and sides  534 ,  536 . In the illustrated embodiment, the sides  534 ,  536  are longer than the ends  530 ,  532 . Optionally, the base  518  may have the same profile as the base  418  (e.g., ends  530 ,  532  and sides  534 ,  536  having the same lengths as the ends  430 ,  432  and sides  434 ,  436  all shown in  FIG. 11 ). 
     The mating portion  516  includes first and second plates  540 ,  542  opposing each other across a mating space  544 . Optionally, the mating portion  516  may be identical to the mating portion  416  (e.g., have identical plates as the plates  440 ,  442  all shown in  FIG. 11 ). The weld tab terminal  510  is configured to receive the corresponding header tab terminal in the mating space  544 . In an exemplary embodiment, the plates  540 ,  542  each include an interior  546  defining the mating space  544  therebetween and an exterior  548  opposite the interior  546 . The plates  540 ,  542  extend between an inner end  550  and an outer end  552 . The inner end  550  is provided at the base  518  while the outer end  552  is the distal end of the corresponding plates  540 ,  542 . Optionally, the central portion of the plates  540 ,  542  may be recessed towards each other in the mating space  544 . For example, lips  554  may be provided at or near the inner and outer ends  550 ,  552  to recess the central portion inward. In an exemplary embodiment, the plates  540 ,  542  include flanges  556  at the outer end  552 . The flanges  556  may be wider and/or longer than other portions of the plates  540 ,  542 . For example, one or more windows  558  may be defined between corresponding flanges  556 . In an exemplary embodiment, the weld tab terminal  510  includes pockets  560  between the base  518  and the inner end  550  of the plates  540 ,  542 . The flanges  556 , the windows  558 , the pockets  560  and/or other components or features may be used to secure other components to the weld tab terminal  510 , such as spring clips. 
       FIG. 13  illustrates a right angle spring clip  600  formed in accordance with an exemplary embodiment. The spring clip  600  includes a spring clip body  602 . In an exemplary embodiment, the spring clip body  602  is stamped and formed from a conductive sheet. In the illustrated embodiment, the spring clip body  602  includes an outer shell  604 , which is generally box shaped. The outer shell  604  may have other shapes in alternative embodiments. In an exemplary embodiment, the spring clip  600  includes first and second inner spring plates  606 ,  608  folded inward into the interior of the outer shell  604 . The spring clip body  602  includes a slot  610  defined between the first and second inner spring plates  606 ,  608 . The slot  610  is configured to receive the corresponding header tab terminal. The inner spring plates  606 ,  608  are configured to be electrically connected to the corresponding header tab terminal. The inner spring plates  606 ,  608  are configured to be electrically connected to the corresponding terminal body of the power terminal to electrically connect the power terminal to the header tab terminal. In various embodiments, the spring clip body  602  only includes a single inner spring plate  606  or  608 . 
     In an exemplary embodiment, the spring clip body  602  includes opposed first and second sides  612 ,  614  and ends  616  extending between the sides  612 ,  614 . In the illustrated embodiment, the sides  612 ,  614  are upper and lower sides; however, the spring clip  600  may be arranged in any orientation and does not require the sides  612 ,  614  to be upper and lower sides. One of the ends  616  is a loading end and is open to receive the corresponding terminal body of the corresponding power terminal. One of the ends  616  includes an opening  618  to the slot  610 . Other of the ends  616  may be closed by end walls  628 . 
     In an exemplary embodiment, the spring clip body  602  includes one or more housing latches  620  used to secure the spring clip  600  in the corresponding housing of the electrical connector. The housing latches  620  may be deflectable. Optionally, both sides  612 ,  614  include housing latches  620 . The spring clip body  602  includes a plurality of power terminal latches  622  configured to engage and hold the spring clip on the corresponding terminal body of the power terminal. For example, the power terminal latches  622  may be formed in the sides  612 ,  614  and bent inward into the interior of the spring clip  600 . The spring clip body  602  includes windows  624  that receive portions of the power terminal to position the spring clip  600  on the corresponding terminal body of the power terminal. The spring clip  600  may include other features to interact with the corresponding terminal body of the corresponding power terminal. 
       FIG. 14  is a perspective view of an in-line spring clip  700  formed in accordance with an exemplary embodiment. The spring clip  700  includes a spring clip body  702 . In an exemplary embodiment, the spring clip body  702  is stamped and formed from a conductive sheet. In the illustrated embodiment, the spring clip body  702  includes an outer shell  704 , which is generally box shaped. The outer shell  704  may have other shapes in alternative embodiments. In an exemplary embodiment, the spring clip  700  includes first and second inner spring plates  706 ,  708  folded inward into the interior of the outer shell  704 . The spring clip body  702  includes a slot  710  defined between the first and second inner spring plates  706 ,  708 . The slot  710  is configured to receive the corresponding header tab terminal. In an exemplary embodiment, the slot  710  is provided opposite the loading end. The inner spring plates  706 ,  708  are configured to be electrically connected to the corresponding header tab terminal. The inner spring plates  706 ,  708  are configured to be electrically connected to the corresponding terminal body of the power terminal to electrically connect the power terminal to the header tab terminal. In various embodiments, the spring clip body  702  only includes a single inner spring plate  706  or  708 . 
     In an exemplary embodiment, the spring clip body  702  includes opposed first and second sides  712 ,  714  and ends  716  extending between the sides  712 ,  714 . In the illustrated embodiment, the sides  712 ,  714  are upper and lower sides; however, the spring clip  700  may be arranged in any orientation and does not require the sides  712 ,  714  to be upper and lower sides. One of the ends  716  is a loading end and is open to receive the corresponding terminal body of the corresponding power terminal. The end  716  opposite the loading end includes an opening  718  to the slot  710 . Other of the ends  716  may be closed by end walls  728 . 
     In an exemplary embodiment, the spring clip body  702  includes one or more housing latches  720  used to secure the spring clip  700  in the corresponding housing of the electrical connector. The housing latches  720  may be deflectable. Optionally, both sides  712 ,  714  include housing latches  720 . The spring clip body  702  includes a plurality of power terminal latches  722  configured to engage and hold the spring clip on the corresponding terminal body of the power terminal. For example, the power terminal latches  722  may be formed in the sides  712 ,  714  and bent inward into the interior of the spring clip  700 . The spring clip body  702  includes windows  724  that receive portions of the power terminal to position the spring clip  700  on the corresponding terminal body of the power terminal. The spring clip  700  may include other features to interact with the corresponding terminal body of the corresponding power terminal. 
     Returning to  FIGS. 7-10  the power terminals  400 ,  402 ,  404 ,  406  are combinations of the various components, such as the crimp terminal  410 , the weld tab terminal  510 , the right angle spring clip  600  and the in-line spring clip  700 . For example, the right angle crimp power terminal  400  includes the crimp terminal  410  and the right angle spring clip  600  coupled to the crimp terminal  410 . The in-line crimp power terminal  402  includes the crimp terminal  410  with the in-line spring clip  700  coupled to the crimp terminal  410 . The right angle weld tab power terminal  404  includes the weld tab terminal  510  and the right angle spring clip  600  coupled to the weld tab terminal  510 . The in-line weld tab power terminal  406  includes the weld tab terminal  510  and the in-line spring clip  700  coupled to the weld tab terminal  510 . As such, the combination of two different types of terminals, namely the crimp terminal  410  and the weld tab terminal  510 , and two different types of spring clips, namely the right angle spring clip  600  and the in-line spring clip  700 , yields four different types of power terminal for use in the various electrical connector systems. Both spring clips  600 ,  700  are able to be connected to either type of terminal  410 ,  510  because the terminals  410 ,  510  include substantially similar locating and securing features and both the spring clips  600 ,  700  include substantially similar locating and securing features. As such, to change the mating orientation of the crimp terminal  410  or the weld tab terminal  510  from mating perpendicular to the longitudinal axis  420 ,  520  to parallel to the longitudinal axis  420 ,  520 , the assembler merely selects the right angle spring clip  600  or the in-line spring clip  700  and couples such spring clip  600 ,  700  to the crimp terminal  410  or the weld tab terminal  510 . As such, a family of power terminals  400 - 406  is provided with a limited number of parts, namely two different types of terminals (configured to be terminated to the power wire in different manners) and two different types of spring clips. 
       FIG. 15  illustrates the right angle crimp power terminal  400  terminated to the corresponding header tab terminal  122 . The right angle crimp power terminal  400  is mated to the header tab terminal  122  in a mating direction that is perpendicular to the longitudinal axis  420 . The right angle spring clip  600  receives the header tab terminal  122  at a right angle or 90° with respect to the longitudinal axis  420 . The right angle weld tab terminal  404  (shown in  FIG. 9 ) may receive the right angle spring clip  600  in a similar manner as described herein. 
     The right angle spring clip  600  is coupled to the crimp terminal  410 . For example, the spring clip  600  may be loaded onto the mating portion  416  through a loading end  626  of the spring clip  600 . The first and second plates  440 ,  442  may be positioned between the inner spring plates  606 ,  608  and the first and second sides  612 ,  614 , respectively. As such, the inner spring plates  606 ,  608  wrap around the plates  440 ,  442  of the mating portion  416  of the crimp terminal  410 . The power terminal latches  622  may be bent into place after the spring clip  600  is coupled to the mating portion  416 . For example, the power terminal latches  622  may be bent into corresponding pockets  460 . When the spring clip  600  is coupled to the crimp terminal  410 , an end wall  628  at the end opposite the loading end  626  is received in the windows  458  at the outer ends  452  of the plates  440 ,  442 . The flanges  456  may protrude at least partially through the windows  624  in the spring clip  600 . In an exemplary embodiment, the flanges  456  of the first and second plates  440 ,  442  are spaced apart far enough to accommodate the touch safe cover  140  on the header tab terminal  122 . 
       FIG. 16  is a cross-sectional view of the right angle crimp power terminal  400  showing the right angle spring clip  600  coupled to the crimp terminal  410 .  FIG. 16  illustrates the inner spring plate  608 ; however, it is realized that the inner spring plate  606  (shown in  FIG. 15 ) may include similar or identical features as the inner spring plate  608 . The walls of the spring clip body  602  wrap snugly around the crimp terminal  410  to position the spring clip  600  on the crimp terminal  410 . For example, the power terminal latches  622  are received in corresponding pockets  460 . The end wall  628  is received in the corresponding window  458 . The flanges  456  are received in corresponding windows  624 . 
     The inner spring plate  608  extends from a front  640  to a rear  642 . The front  640  is generally defined at the opening  618  to the slot  610 . The rear  642  may extend to the end  616  of the outer shell  604  generally opposite the opening  618 . In the illustrated embodiment, the spring clip  600  is oriented such that the inner spring plate  608  extends across the crimp terminal  410  (e.g., perpendicular to the longitudinal axis  420 ). 
     The inner spring plate  608  includes a plurality of contact springs that are used to electrically and mechanically engage the header tab terminal and/or the terminal body  412 . In an exemplary embodiment, the inner spring plate  608  includes different types of contact springs to provide different functions. For example, the inner spring plate  608  includes one or more cantilevered contact springs  644 , one or more stabilization contact springs  646 , and one or more forward contact springs  648 . The cantilevered contact springs  644  provide the main electrical connection to the header tab terminal  122 . The stabilization contact springs  646  provide the main mechanical connection with the header tab terminal. The forward contact spring  648  provides the last mated interface between the power terminal  400  and the header tab terminal during unmating to ensure that the HVIL circuit is opened prior to the high power circuit being opened. In the illustrated embodiment, the forward contact spring  648  is the forward most contact spring, closest to the front  640 . In the illustrated embodiment, the cantilevered contact springs  644  and the stabilization contact springs  646  are provided at or near a central portion of the inner spring plate  608 . 
     The inner spring plate  608  includes a forward plate portion  650  and a rearward plate portion  652  separated by one or more openings  654 . The contact springs  644 ,  646 ,  648  may be stamped from the inner spring plate  608  at the one or more opening  654 . In an exemplary embodiment, the stabilization contact springs  646  bridge between and connect to both the forward plate portion  650  and the rearward plate portion  652 . Optionally, the stabilization contact springs  646  may be the only portions of the inner spring plate  608  spanning between the forward plate portion  650  and the rearward plate portion  652 . 
     In an exemplary embodiment, the cantilevered contact springs  644  extend only partially across the opening  654 . For example, in the illustrated embodiment, the inner spring plate  608  includes a plurality of cantilevered contact springs  644  extending from the forward plate portion  650  and a plurality of cantilevered contact springs  644  extending from the rearward plate portion  652 . Optionally, such cantilevered contact springs  644  may oppose each other across the opening  654 . 
     Any number of contact springs may be provided. In the illustrated embodiment, the inner spring plate  608  includes a pair of stabilizing contact springs  646  flanking a plurality of the cantilevered contact springs  644 . The stabilization contact springs  646  are provided as the outer most contact springs while the cantilevered contact springs  644  are the inner contact springs. 
       FIG. 17  is a partial sectional view of the right angle crimp power terminal  400  mated to the header tab terminal  122 .  FIG. 18  is a cross sectional view of the right angle crimp power terminal  400  mated to the header tab terminal  122 .  FIGS. 17 and 18  illustrate the cantilevered contact springs  644  spring biased against and electrically connected to the header tab terminal  122  and the plates  440 ,  442  of the crimp terminal  410 . 
     The cantilevered contact springs  644  include fixed ends  660  extending from the corresponding inner spring plates  606 ,  608  and free ends  662  configured to be resiliently deflected against the header tab terminal  122  when the header tab terminal  122  is received in the slot  610 . 
     In an exemplary embodiment, the free ends  662  are curved and define bumps configured to engage the header tab terminal  122 . The bumps define contact interfaces  664  with the header tab terminal  122 . When the cantilevered contact springs  644  are resiliently deflected outward by the header tab terminal  122 , the cantilevered contact springs  644  are spring biased against the header tab terminal  122  and provide a contact normal force against the header tab terminal  122 , ensuring electrical connection between the cantilevered contact springs  644  and the header tab terminal  122 . 
     In an exemplary embodiment, the fixed ends  660  include knuckles  668  protruding toward the plates  440 ,  442  of the crimp terminal  410 . The knuckles  668  define contact interfaces  664  with the plates  440 ,  442 . As such, the spring clip  660  is electrically connected to the crimp terminal  410  though the plates  440 ,  442 . The spring clip  600  is electrically connected to the header tab terminal  122  through the cantilevered contact springs  644 . In an exemplary embodiment, the cantilevered contact springs  644  define multiple points of contact with the power terminal  400  and multiple points of contact with the header tab terminal  122 . An electrical connection is made between the crimp terminal  410  and the header tab terminal  122  through the spring clip  600 . 
       FIG. 19  is a partial sectional view of the right angle crimp power terminal  400  mated to the header tab terminal  122 .  FIG. 20  is a cross sectional view of the right angle crimp power terminal  400  mated to the header tab terminal  122 .  FIGS. 19 and 20  illustrate the stabilization contact springs  646  spring biased against and electrically connected to the header tab terminal  122  and the plates  440 ,  442  of the crimp terminal  410 . 
     The stabilization contact springs  646  each include a first fixed end  670  and a second fixed end  672  fixed to the forward plate portion  650  and the rearward plate portion  652 , respectively. The stabilization contact springs  646  include a mating hub  674  mated with the header tab terminal  122 . The mating hub  674  may be approximately centered between the fixed ends  670 ,  672 . The mating hub  674  is configured to be resiliently deflected against the header tab terminal  122  when the header tab terminal  122  is received in the slot  610 . 
     In an exemplary embodiment, the mating hub  674  may include one or more curves defining bumps configured to engage the header tab terminal  122 . Optionally, the stabilization contact spring  646 , including the mating hub, may have an M-shape or W-shape defining multiple points of contact with the header tab terminal  122 . The bumps define contact interfaces  676  with the header tab terminal  122 . 
     When the stabilization contact springs  646  are resiliently deflected outward from the slot  610  by the header tab terminal  122 , the mating hub  674  is spring biased against the header tab terminal  122  and provides a contact normal force against the header tab terminal  122 , ensuring a strong mechanical and electrical connection between the stabilization contact spring  646  and the header tab terminal  122 . Because the stabilization contact spring  646  is fixed at both ends, the amount of deflection causes a greater normal force pressing against the header tab terminal  122  than the cantilevered contact spring  644  (shown in  FIGS. 17-18 ). As such, the normal force imparted by each stabilization contact spring  646  is greater than the normal force imparted by any cantilevered contact spring  644 . 
     In an exemplary embodiment, the fixed ends  670 ,  672  include knuckles  678  protruding toward the plates  440 ,  442  of the crimp terminal  410 . The knuckles  678  define contact interfaces  676  with the plates  440 ,  442 . Optionally, when the stabilization contact spring  646  is deflected by the header tab terminal  122 , a central portion of the mating hub  674  may be pressed outward against the corresponding plate  440 ,  442  to define a contact interface  676  between the mating hub  674  and the plate  440 ,  442 . Such engagement with the plate  440 ,  442  by the mating hub  674  may increase the contact normal force of the stabilization contact spring  646  against the header tab terminal  122 . 
     The spring clip  600  is electrically connected to the crimp terminal  410  though the plates  440 ,  442 . The spring clip  600  is electrically connected to the header tab terminal  122  through the cantilevered contact springs  644 . In an exemplary embodiment, the stabilization contact springs  646  define multiple points of contact with the power terminal  400  and multiple points of contact with the header tab terminal  122 . An electrical connection is made between the crimp terminal  410  and the header tab terminal  122  through the spring clip  600 . 
       FIG. 21  is a partial sectional view of the right angle crimp power terminal  400  mated to the header tab terminal  122 .  FIG. 22  is a cross sectional view of the right angle crimp power terminal  400  mated to the header tab terminal  122 .  FIGS. 21 and 22  illustrate the forward contact springs  648  spring biased against and electrically connected to the header tab terminal  122  and the plates  440 ,  442  of the crimp terminal  410 . The forward contact springs  648  are aligned with corresponding cantilevered contact springs  644 . The forward contact springs  648  may be similar to the cantilevered contact springs  648 ; however, the forward contact springs  648  may be located forward of other cantilevered contact springs  644 , such as at or near the opening  618  to the slot  610 . 
     The forward contact springs  648  include fixed ends  680  extending from the corresponding inner spring plates  606 ,  608  and free ends  682  configured to be resiliently deflected against the header tab terminal  122  when the header tab terminal  122  is received in the slot  610 . In an exemplary embodiment, the free ends  682  are curved and define bumps configured to engage the header tab terminal  122 . The bumps define contact interfaces  684  with the header tab terminal  122 . 
       FIG. 23  illustrates the in-line crimp power terminal  402  terminated to the corresponding header tab terminal  122 . The in-line crimp power terminal  402  is mated to the header tab terminal  122  in a mating direction that is parallel to the longitudinal axis  420 . The in-line spring clip  700  receives the header tab terminal  122  in a mating direction parallel to the longitudinal axis  420 . The in-line weld tab terminal  406  (shown in  FIG. 10 ) may receive the in-line spring clip  700  in a similar manner as described herein. 
     The right angle spring clip  700  is coupled to the crimp terminal  410 . For example, the spring clip  700  may be loaded onto the mating portion  416  through a loading end  726  of the spring clip  700 . The first and second plates  440 ,  442  may be positioned between the inner spring plates  706 ,  708  and the first and second sides  712 ,  714 , respectively. As such, the inner spring plates  706 ,  708  wrap around the plates  440 ,  442  of the mating portion  416  of the crimp terminal  410 . The power terminal latches  722  may be bent into place after the spring clip  700  is coupled to the mating portion  416 . For example, the power terminal latches  722  may be bent into corresponding pockets  460 . When the spring clip  700  is coupled to the crimp terminal  410 , an end wall  728  is received in the windows  458  at the outer ends  452  of the plates  440 ,  442 . The flanges  456  may protrude at least partially through the windows  724  in the spring clip  700 . In an exemplary embodiment, the flanges  456  of the first and second plates  440 ,  442  are spaced apart far enough to accommodate the touch safe cover  140  on the header tab terminal  122 . 
       FIG. 24  is a cross-sectional view of the in-line crimp power terminal  402  showing the right angle spring clip  700  coupled to the crimp terminal  410 .  FIG. 25  is a partial sectional view of the in-line crimp power terminal  402 .  FIGS. 24 and 25  illustrates the inner spring plate  708 ; however, it is realized that the inner spring plate  706  (shown in  FIG. 23 ) may include similar or identical features as the inner spring plate  708 . The walls of the spring clip body  702  wrap snugly around the crimp terminal  410  to position the spring clip  700  on the crimp terminal  410 . For example, the power terminal latches  722  are received in corresponding pockets  460 . The end wall  728  is received in the corresponding window  458 . The flanges  456  are received in corresponding windows  724 . 
     The inner spring plate  708  extends from a front  740  to a rear  742 . The front  740  is generally defined at the opening  718  to the slot  710 . The rear  742  may extend to an area at or near the loading end  726  of the outer shell  704  generally opposite the opening  718 . In the illustrated embodiment, the spring clip  700  is oriented such that the inner spring plate  708  extends along the crimp terminal  410  (e.g., parallel to the longitudinal axis  420 ). 
     The inner spring plate  708  includes a plurality of contact springs that are used to electrically and mechanically engage the header tab terminal and/or the terminal body  412 . In an exemplary embodiment, the inner spring plate  708  includes different types of contact springs to provide different functions. For example, the inner spring plate  708  includes one or more cantilevered contact springs  744 , one or more stabilization contact springs  746 , and one or more forward contact springs  748 . The cantilevered contact springs  744  may be substantially similar to the cantilevered contact springs  644  (shown in  FIG. 16 ) and like components may be referred to with like reference numerals. The stabilization contact springs  746  may be substantially similar to the stabilization contact springs  646  (shown in  FIG. 16 ) and like components may be referred to with like reference numerals. The forward contact springs  748  may be substantially similar to the forward contact springs  648  (shown in  FIG. 16 ) and like components may be referred to with like reference numerals. 
     The cantilevered contact springs  744  provide the main electrical connection to the header tab terminal  122 . The stabilization contact springs  746  provide the main mechanical connection with the header tab terminal. The forward contact spring  748  provides the last mated interface between the power terminal  400  and the header tab terminal during unmating to ensure that the HVIL circuit is opened prior to the high power circuit being opened. In the illustrated embodiment, the forward contact spring  748  is the forward most contact spring, closest to the front  740 . In the illustrated embodiment, the cantilevered contact springs  744  and the stabilization contact springs  746  are provided at or near a central portion of the inner spring plate  708 . 
     The inner spring plate  708  includes a forward plate portion  750  and a rearward plate portion  752  separated by one or more openings  754 . The contact springs  744 ,  746 ,  748  may be stamped from the inner spring plate  708  at the one or more opening  754 . In an exemplary embodiment, the stabilization contact springs  746  bridge between and connect to both the forward plate portion  750  and the rearward plate portion  752 . Optionally, the stabilization contact springs  746  may be the only portions of the inner spring plate  708  spanning between the forward plate portion  750  and the rearward plate portion  752 . 
     In an exemplary embodiment, the cantilevered contact springs  744  extend only partially across the opening  754 . For example, in the illustrated embodiment, the inner spring plate  708  includes a plurality of cantilevered contact springs  744  extending from the forward plate portion  750  and a plurality of cantilevered contact springs  744  extending from the rearward plate portion  752 . Optionally, such cantilevered contact springs  744  may oppose each other across the opening  754 . 
     Any number of contact springs may be provided. In the illustrated embodiment, the inner spring plate  708  includes a pair of stabilizing contact springs  746  flanking a plurality of the cantilevered contact springs  744 . The stabilization contact springs  746  are provided as the outer most contact springs while the cantilevered contact springs  744  are the inner contact springs. 
       FIGS. 26-28  illustrate an unmating sequence of the electrical connector  204  from the header connector  202 .  FIGS. 26-28  illustrate an unmating sequence of the power terminals  220  from the header tab terminals  214  and of the HVIL terminal  228  from the HVIL contacts  226 .  FIG. 26  illustrates the electrical connector  204  in a mated position.  FIG. 27  illustrates the electrical connector  204  in a partially unmated position.  FIG. 28  illustrates the electrical connector  204  in a partially unmated position. 
     The housing  230  of the electrical connector  204  includes a terminal chamber  240  and an HVIL terminal chamber  242 . The HVIL terminal  228  is received in the terminal chamber  240 . The HVIL terminal  228  has a mating interface  244  configured to be mated to and unmated from the HVIL contact  226  to control the high voltage circuit of the electrical connector  204 . The power terminal  230  is received in the terminal chamber  240  and is configured for electrical connection with the header tab terminal  214  when the electrical connector  204  is mated with the header connector  202 . 
     When mated ( FIG. 26 ), the HVIL circuit and the high voltage circuit are both closed and thus the high voltage circuit is operational. During unmating, the HVIL circuit is initially opened ( FIG. 27 ), such as by partially unmating the electrical connector  204  from the header connector  202 . The HVIL terminal  228  of the electrical connector  204  is unmated from the HVIL contacts  226  of the header connector  202 . When the HVIL circuit is opened ( FIG. 27 ), the system  200  will shut off the high voltage circuit to cease power flow through the power terminal  220  and the header tab terminal  214 . However, to prevent damage, such as from arcing, the power terminal  220  is still mated with the header tab terminal  214  even when the HVIL circuit is initially opened ( FIG. 27 ). For example, as shown in  FIG. 27 , the forward contact springs  648 , which are the forward-most contact springs (e.g., the contact springs closest to the opening  618  to the slot  610 ), maintain electrical contact with the header tab terminal  214  after the HVIL circuit is opened. Further unmating ( FIG. 28 ) completely unmates the power terminal  220  from the header tab terminal  214 . The forward contact springs  648  are configured to be unmated from the header tab terminal  214  after the cantilevered contact springs  644  are unmated from the header tab terminal  214  when the electrical connector  204  is unmated from the header connector  202 . 
     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, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.