Patent Publication Number: US-2023136832-A1

Title: Low-profile electrical connector

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of priority of U.S. Provisional Application No. 63/273,323 filed Oct. 29, 2021, entitled “LOW-PROFILE ELECTRICAL CONNECTOR” (Attorney Docket No. A1156.70779US00), the entire contents of which is incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     This disclosure relates generally to electrical interconnection systems and more specifically to low-profile electrical connectors for electrically interconnecting two circuit boards. 
     BACKGROUND 
     Electrical connectors are used in many electronic systems. In general, various electronic devices (e.g., smart phones, tablet computers, desktop computers, notebook computers, digital cameras, and the like) have been provided with assorted types of connectors whose primary purpose is to enable separable connections for exchanging power, data, commands, and/or other signals between subassemblies of an electronic device. Electrical connectors are basic components needed to make some electrical systems functional. Connectors in many configurations are commercially available, differing in design based on the device configuration in which they are intended to be used, as well as other parameters of use, such as number and speed of data signals and/or the amount of current or number of power circuits that are to pass through the connector. Mechanical parameters of connector operation may also vary from connector to connector, such as the desired mating or contact force. 
     As a result of the range of parameters that may impact connector selection and performance, a designer of an electronic system may spend considerable time on connector selection and qualification. As the designer creates designs for a new device, the designer may investigate available connectors to select a particular connector as a candidate for use in manufacture of the device. Before manufacturing that device in quantity, however, the designer may qualify the selected connector, including testing the performance and reliability of the selected connector to ensure that it work in the device when mass produced. This selection and qualification can be time consuming and may be repeated for each new device design as well as modifications of an existing device design that results in the need to select a different connector. 
     As electronic devices become smaller and smaller, electrical connectors may need to be deployed in very small spaces. One factor designers may take into consideration in manufacturing a small electronic device is whether there is room to house all the electrical connections required for proper functioning of the electronic device. 
     SUMMARY 
     According to aspects of the present technology, an electrical connector is provided. The electrical connector may be comprised of: an insulative housing comprised of a mating interface configured to face a mating connector when the electrical connector and the mating connector are in a mated position; a plurality of conductive power terminals attached to the housing and exposed at the mating interface; and a plurality of conductive signal terminals attached to the housing and exposed at the mating interface. The housing may be configured to be mounted on a circuit board such that a side surface of the housing is aligned with an edge of the circuit board. 
     In an aspect, the side surface of the housing may be configured to be aligned with the edge of the circuit board such that, when the electrical connector and the mating connector are in the mated position, the circuit board is parallel with a corresponding circuit board on which the mating connector is mounted such that the edge of the circuit board faces an edge of the corresponding circuit board. In some embodiments of this aspect, the housing may be configured to be mounted on the circuit board such that a bottom surface of the housing faces a surface of the circuit board and a top surface of the housing faces away from the surface of the circuit board, the side surface of the housing may be perpendicular to the bottom surface of the housing, and a height of the housing, extending perpendicularly from the bottom surface of the housing to the top surface of the housing, may be in a range from 5.0 mm to 14.0 mm. For example, the height of the housing may be in a range from 6.0 mm to 12.0 mm. 
     In some embodiments of this aspect, each of the power terminals may be comprised of a body portion, a mounting portion extending in a first direction from the body portion, and a contact portion extending in a second direction from the body portion, the second direction being perpendicular to the first direction. The mounting portions of the power terminals may be configured to be attached to the circuit board, and the contact portions of the power terminals may be configured to contact corresponding power terminals of the mating connector when the electrical connector and the mating connector are in the mated position. The contact portions of the power terminals may be aligned in a row direction parallel to the bottom surface of the housing, and the height of the housing may be in a range from 6.5 mm to 8.5 mm. In some embodiments, the power terminals may be comprised of pairs of first and second power terminals. For each of the pairs of first and second power terminals, the contact portion of the first power terminal may be a mirror image of the contact portion of the second power terminal. In some embodiments, the contact portions of the power terminals may be arranged in an array comprised of a plurality of columns aligned perpendicular to the bottom surface of the housing and a plurality of rows aligned parallel to the bottom surface of the housing, and the height of the housing may be in a range from 10.0 mm to 12.0 mm. In some embodiments, each of the columns of the array may be comprised of a pair of first and second power terminals of the power terminals, in which the first power terminals of the array are aligned in a first row, and in which the second power terminals of the array are aligned in a second row. For each column of the array, the contact portion the first power terminal may be a mirror image of the contact portion of the second power terminal. 
     In some embodiments of this aspect, each of the signal terminals may be comprised of a mounting portion extending in a first direction and a contact portion extending in a second direction, the second direction being perpendicular to the first direction, the mounting portions of the signal terminals may be configured to be attached to the circuit board, and the contact portions of the signal terminals may be configured to contact corresponding signal terminals of the mating connector when the electrical connector and the mating connector are in the mated position. In some embodiments, the contact portions of the signal terminals may be arranged in an array comprised of a plurality of columns aligned perpendicular to the bottom surface of the housing and a plurality of rows aligned parallel to the bottom surface of the housing. 
     In some embodiments of this aspect, the housing may be comprised of first and second mounting ends located on opposite sides of the housing, and the housing may be configured to be attached to the circuit board by first and second retainer clips respectively disposed in the first and second mounting ends. In some embodiments, each of the first and second mounting ends of the housing may be comprised of an alignment structure configured to engage with a corresponding alignment structure of the mating connector when the electrical connector and the mating connector are in the mated position. 
     In another aspect, the electrical connector may be a receptacle connector. In some embodiments of this aspect, the mating interface of the housing may be comprised of a protruding engagement section that extends beyond the side surface of the housing, and the engagement section of the mating interface may be comprised of a plurality of first contact openings through which the power terminals are exposed and a plurality of second contact openings through which the signal terminals are exposed. In some embodiments, when the housing is mounted on the circuit board, a mating direction of the electrical connector with the mating connector may be parallel to a surface of the circuit board. In some embodiments, the engagement section of the mating interface may be configured to be received in an accommodation space of the mating connector when the electrical connector and the mating connector are in the mated position. 
     In some embodiments of this aspect, the contact portions of the power terminals and the contact portions of the signal terminals may be disposed in the engagement section of the mating interface. The contact portions of the power terminals may be comprised of power tabs. For each of the power terminals, the power tab and the mounting portion may extend from the body portion in perpendicular directions. In some embodiments, the power terminals may be aligned in a row direction in pairs comprised of a first power terminal and a second power terminal and, for each of the pairs of the power terminals, a distance in the row direction between a midpoint of the first contact opening corresponding to the first power terminal and a midpoint of the first contact opening corresponding to the second power terminal may be in a range from 2.5 mm to 3.5 mm. For adjacent pairs of the power terminals, a distance between the midpoints of the first contact openings corresponding to the first power terminals may be in a range from 5.5 mm to 6.5 mm. In some embodiments, for each of the pairs of the power terminals, a contact surface of the power tab of the first power terminal and a contact surface of the power tab of the second power terminal may face in opposite directions. 
     In some embodiments of this aspect, the power terminals may be arranged such that the power tabs of the power terminals are disposed in the engagement section of the mating interface in columns and rows such that each column is comprised of a pair of first and second power terminals of the power terminals, and a length of the mounting portions of the first power terminals may be shorter than a length of the mounting portions of the second power terminals. In some embodiments, for each of the pairs of first and second power terminals, the power tab of the first power terminal may have a curved section that is a mirror image of a curved section of the power tab of the second power terminal. The power tabs of the power terminals may be configured to press against the corresponding power terminals of the mating connector when the electrical connector and the mating connector are in the mated position. In some embodiments, for each of the columns of the power terminals, a distance in a column direction between a midpoint of the first contact opening corresponding to the first power terminal and a midpoint of the first contact opening corresponding to the second power terminal may be in a range from 1.5 mm to 2.5 mm. For adjacent pairs of the first and second power terminals, a distance in a row direction between the midpoints of the first contact openings corresponding to the first power terminals may be in a range from 6.5 mm to 7.5 mm. In some embodiments, for each of the columns of the power terminals, a contact surface of the power tab of the first power terminal and a contact surface of the power tab of the second power terminal may face in opposite directions. 
     In some embodiments of this aspect, the contact portions of the signal terminals may be comprised of contact clips, and each of the contact clips may be configured to receive a corresponding signal-pin of the mating connector when the mating connector and the electrical connector are in the mated position. In some embodiments, each of the contact clips of the signal terminals may be comprised of: a first arm comprised of a first contact surface, and a second arm comprised of a second contact surface. For each of the contact clips, the first and second contact surfaces may face each other and may be configured to receive the corresponding signal-pin of the mating connector therebetween, with a distance between the first and second contact surfaces being such that the corresponding signal-pin is pinched by the first and second contact surfaces when the mating connector and the electrical connector are in the mated position. In some embodiments, for each of the signal terminals, the contact clip and the mounting portion may extend in perpendicular directions. In some embodiments, the signal terminals may be arranged such that the contact clips of the signal terminals are disposed in the engagement section of the mating interface in columns and rows such that each of the columns is comprised of the contact clips of at least two of the signal terminals. For each of the columns of the signal terminals, the mounting portions of the at least two of the signal terminals may have different lengths from each other. In some embodiments, each of the columns of the signal terminals may be comprised of a first signal terminal and a second signal terminal, and a shape of the mounting portion of the first signal terminal may be different from a shape of the mounting portion of the second signal terminal. 
     In some embodiments of this aspect, each of the alignment structures of the first and second mounting ends of the housing may be comprised of a multi-level protrusion configured to be received in a corresponding mating recess of the mating connector when the mating connector and the electrical connector are in the mated position. The engagement section of the mating interface may extend beyond the side surface of the housing by a first distance, and each of the multi-level protrusions may extend beyond the side surface of the housing by a second distance greater than the first distance. In some embodiments, each of the multi-level protrusions may be comprised of a sublevel that extends beyond the side surface of the housing by a third distance less than the second distance and greater than the first distance. In some embodiments, the multi-level protrusions of the first and second end portions may be contiguous with the engagement section of the mating interface, and, in a mating operation, the multi-level protrusions may be received in the corresponding mating recesses of the mating connector before the engagement section is received in an accommodation space of the mating connector. 
     In another aspect, the electrical connector may be a plug connector. In some embodiments of this aspect, the side surface of the housing may be an outermost surface of the housing and may be configured to be aligned with the edge of the circuit board such that no part of the housing extends beyond the edge of the circuit board when the housing is mounted on the circuit board. The mating interface of the housing may be comprised of an accommodation space configured to receive a protruding engagement section of the mating connector when the electrical connector and the mating connector are in the mated position. When the housing is mounted on the circuit board, a mating direction of the electrical connector with the mating connector may be parallel to a surface of the circuit board. The contact portions of the power terminals and the contact portions of the signal terminals may be disposed in the accommodation space. 
     In some embodiments of this aspect, for each of the power terminals, the contact portion may be comprised of a set of fingers extending from the body portion in the first direction. The fingers may be configured to press against a corresponding power tab of the mating connector when the mating connector and the electrical connector are in the mated position. For each of the power terminals, the fingers and the mounting portion may extend from the body portion in perpendicular directions. In some embodiments, the power terminals may be aligned in a row direction in pairs comprised of a first power terminal and a second power terminal. For each of the pairs of the power terminals, a distance in the row direction between a midpoint of the body portion of the first power terminal and a midpoint of the body portion of the second power terminal may be in a range from 2.5 mm to 3.5 mm. For adjacent pairs of the power terminals, a distance between midpoints of the first power terminals may be in a range from 5.5 mm to 6.5 mm. In some embodiments, for each of the pairs of the power terminals, a contact surface of the set of fingers of the first power terminal and a contact surface of the set of fingers of the second power terminal may face in opposite directions. 
     In some embodiments of this aspect, the power terminals may be arranged such that the sets of fingers of the power terminals are disposed in the accommodation space of the mating interface in columns and rows such that each column is comprised of a pair of first and second power terminals of the power terminals. For each of the columns of the power terminals, a length of the mounting portion of the first power terminal may be shorter than a length of the mounting portion of the second power terminal. In some embodiments, for each of the columns of the power terminals, the fingers of the first power terminal may have a curved section that is a mirror image of a curved section of the fingers of the second power terminal. In some embodiments, for each of the columns of the power terminals, a distance in a column direction between a midpoint of the first power terminal and a midpoint of the second power terminal may be in a range from 1.5 mm to 2.5 mm. In some embodiments, for adjacent columns of the power terminals, a distance in a row direction between the midpoints of the first power terminals may be in a range from 6.5 mm to 7.5 mm. In some embodiments, for each of the columns of the power terminals, a contact surface of the set of fingers of the first power terminal and a contact surface of the set of fingers of the second power terminal may face in opposite directions. 
     In some embodiments of this aspect, the contact portions of the signal terminals may be comprised of contact pins, and each of the contact pins may be configured to be inserted in a corresponding signal clip of the mating connector when the mating connector and the electrical connector are in the mated position. In some embodiments, for each of the signal terminals, the contact pin and the mounting portion may extend in perpendicular directions. In some embodiments, the signal terminals may be arranged such that the contact pins of the signal terminals are disposed in the accommodation space of the mating interface in columns and rows such that each column is comprised of the contact pins of at least two of the signal terminals. For each of the columns of the signal terminals, the mounting portions of the at least two of the signal terminals may have different lengths from each other. For each of the columns of the signal terminals, the contact pins of the at least two of the signal terminals may have lengths that are different from each other. 
     In some embodiments of this aspect, each of the alignment structures of the first and second mounting ends of the housing may be comprised of a multi-level recess configured to receive a corresponding mating protrusion of the mating connector when the mating connector and the electrical connector are in the mated position. The accommodation space of the mating interface may extend from the side surface into the housing by a first distance, and each of the multi-level recesses may extend from the side surface into the housing by a second distance greater than the first distance. In some embodiments, each of the multi-level recesses may be comprised of a sublevel that extends from the side surface into the housing by a third distance less than the second distance and greater than the first distance. In some embodiments, the multi-level recesses of the first and second end portions may be contiguous with the accommodation space of the mating interface. In a mating operation, the multi-level recesses may receive the corresponding mating protrusions of the mating connector before the accommodation space receives the engagement section of the mating connector. 
     In another aspect, the electrical connector may a plug connector. Each of the power terminals may be comprised of: a body portion, a mounting portion extending in a first direction from the body portion and configured to be attached to the circuit board when the housing is mounted on the circuit board, and a contact portion extending in a second direction from the body portion and configured to contact a corresponding power terminal of the mating connector when the electrical connector and the mating connector are in the mated position, the second direction being opposite to the first direction. Each of the signal terminals may be comprised of: a mounting portion extending in the first direction and configured to be attached to the circuit board when the housing is mounted on the circuit board, and a contact portion extending in the second direction and configured to contact a corresponding signal terminal of the mating connector when the electrical connector and the mating connector are in the mated position. The mating interface of the housing may be comprised of an accommodation space configured to receive a protruding engagement section of the mating connector when the electrical connector and the mating connector are in the mated position. When the housing is mounted on the circuit board, a mating direction of the electrical connector with the mating connector may be perpendicular to a surface of the circuit board. The contact portions of the power terminals and the contact portions of the signal terminals may be disposed in the accommodation space. 
     In some embodiments of this aspect, when the housing is mounted on the circuit board, the side surface of the housing may face a surface of the circuit board, a mating surface of the housing may face away from the surface of the circuit board, and top and bottom surfaces of the housing may be perpendicular to the circuit board. A height of the housing, extending perpendicularly from the bottom surface of the housing to the top surface of the housing, may be in a range from 5.0 mm to 14.0 mm. 
     In some embodiments of this aspect, for each of the power terminals, the contact portion may be comprised of a set of fingers extending from the body portion in the first direction, the fingers being configured to press against a corresponding power tab of the mating connector when the mating connector and the electrical connector are in the mated position. In some embodiments, for each of the power terminals, the set of fingers and the mounting portion may extend from the body portion in opposite directions. In some embodiments, the power terminals may be aligned in a row direction in pairs comprised of first and second power terminals of the power terminals. For each of the pairs of first and second power terminals, a distance in the row direction between a midpoint of the first power terminal and a midpoint of the second power terminal may be in a range from 2.5 mm to 3.5 mm. In some embodiments, a distance between the set of fingers of the first power terminals of adjacent pairs of the power terminals may be in a range from 5.5 mm to 6.5 mm. In some embodiments, for each of the pairs of the power terminals, a contact surface of the fingers of the first power terminal and a contact surface of the fingers of the second power terminal may face in opposite directions. In some embodiments, the power terminals may be arranged such that the sets of fingers of the power terminals are disposed in the accommodation space of the mating interface in columns and rows such that each column is comprised of a pair of first and second power terminals of the power terminals. In some embodiments, for each of the columns of the power terminals, the fingers of the first power terminal may have a curved section that is a mirror image of a curved section of the fingers of the second power terminal. In some embodiments, for each of the columns of the power terminals, a distance in a column direction between a midpoint of the first power terminal and a midpoint of the second power terminal may be in a range from 1.5 mm to 2.5 mm. In some embodiments, for adjacent pairs of the power terminals, a distance in a row direction between the midpoints of the first power terminals may be in a range from 6.5 mm to 7.5 mm. In some embodiments, for each of the columns of the power terminals, a contact surface of the fingers of the first power terminal and a contact surface of the fingers of the second power terminal may face in opposite directions. 
     In some embodiments of this aspect, the contact portions of the signal terminals may be comprised of contact pins, and each of the contact pins may be configured to be inserted in a corresponding signal clip of the mating connector when the mating connector and the electrical connector are in the mated position. In some embodiments, the signal terminals may be arranged such that the contact pins of the signal terminals are disposed in the accommodation space of the mating interface in columns and rows such that each column is comprised of the contact pins of at least two of the signal terminals. 
     In some embodiments of this aspect, each of the alignment structures of the first and second mounting ends of the housing may be comprised of a multi-level recess configured to receive a corresponding mating protrusion of the mating connector when the mating connector and the electrical connector are in the mated position. The accommodation space of the mating interface may extend from the mating surface into the housing by a first distance, and each of the multi-level recesses may extend from the mating surface into the housing by a second distance greater than the first distance. In some embodiments, each of the multi-level protrusions may be comprised of a sublevel that extends from the mating surface into the housing by a third distance less than the second distance and greater than the first distance. In some embodiments, the multi-level recesses of the first and second end portions may be contiguous with the accommodation space of the housing. In a mating operation, the multi-level recesses may receive the corresponding mating protrusions of the mating connector before the accommodation space receives the engagement section of the mating connector. 
     In another aspect, the housing may have a segmented construction such that the housing is comprised of: a plurality of first housing portions aligned in a row direction, with each of the first housing portions being configured to support at least one of the power terminals, a plurality of second housing portions aligned in the row direction, with each of the second housing portions being configured to support a group of the signal terminals, and first and second end housing portions located on opposite ends and sandwiching the first and second housing portions therebetween. In some embodiments of this aspect, each of the first housing portions may be configured to support at least two of the power terminals aligned in a column direction. 
     According to further aspects of the present technology, an electrical connector is provided. The electrical connector may be comprised of: a plurality of power segments aligned in a row direction, each of the power segments being comprised of at least one conductive power terminal attached to a first insulative housing portion, each of the power terminals being configured to be attached to a circuit board; a plurality of signal segments aligned in the row direction, each of the signal segments being comprised of a plurality of conductive signal terminals attached to a second insulative housing portion, each of the signal terminals being configured to be attached to the circuit board; a first end segment comprised of a first insulative end portion and a first retainer clip attached to the first insulative end portion, the first retainer clip being configured to be attached to the circuit board, and a second end segment comprised of a second insulative end portion and a second retainer clip attached to the second insulative end portion, the second retainer clip being configured to be attached to the circuit board. The power segments and the signal segments may be disposed between the first and second end segments. Each of the first and second end segments may be comprised of a mating structure configured to engage with a corresponding mating structure of a mating connector when the electrical connector and the mating connector are in a mated position. The power segments and the signal segments may be sandwiched between the first and second end segments. The first and second housing portions and the first and second end portions may be attached to each other to form a housing comprised of a mating interface configured to engage with a mating interface of the mating connector when the electrical connector and the mating connector are in the mated position. A side surface of the housing may be aligned with an edge of the circuit board when the first and second end segments are attached to the circuit board by the first and second retainer clips. 
     In some embodiments of this aspect, when the first and second end segments are attached to the circuit board, the side surface of housing may be aligned with the edge of the circuit board such that, when the electrical connector and the mating connector are in the mated position, the circuit board is parallel with a corresponding circuit board on which the mating connector is mounted such that the edge of the circuit board faces an edge of the corresponding circuit board. In some embodiments, when the first and second end segments are attached to the circuit board, a bottom surface of the housing may face a surface of the circuit board and a top surface of the housing may face away from the surface of the circuit board. The side surface of the housing may be perpendicular to the bottom surface of the housing. A height of the housing, which extends perpendicularly from the bottom surface of the housing to the top surface of the housing, may be in a range from 5.0 mm to 14.0 mm. In some embodiments, the height of the housing may be in a range from 6.0 mm to 12.0 mm. 
     In some embodiments of this aspect, each of the power terminals may be comprised of a body portion, a mounting portion extending in a first direction from the body portion, and a contact portion extending in a second direction from the body portion, the second direction being perpendicular to the first direction. The mounting portions of the power terminals may be configured to be attached to the circuit board. The contact portions of the power terminals may be configured to contact corresponding power terminals of the mating connector when the electrical connector and the mating connector are in the mated position. In some embodiments, the height of the housing may be in a range from 6.5 mm to 8.5 mm. 
     In some embodiments of this aspect, the power segments may be comprised of pairs of first and second power segments, with each of the first power segments being comprised of a first power terminal of the power terminals, and with each of the second power segments being comprised of a second power terminal of the power terminals. In some embodiments, the first and second power segments may be arranged in an alternating order in the row direction. In some embodiments, for each of the pairs of first and second power segments, the contact portion of the first power terminal may be a mirror image of the contact portion of the second power terminal. 
     In some embodiments of this aspect, each of the power segments may be comprised of a pair of the power terminals, and the pairs of the power terminals may be arranged in an array comprised of a plurality of columns aligned perpendicular to the bottom surface of the housing and a plurality of rows aligned parallel to the bottom surface of the housing. In some embodiments, the height of the housing may be in a range from 10.0 mm to 12.0 mm. In some embodiments, for each of the columns of the array, the contact portions of the pair of the power terminals may be mirror images of each other. 
     In some embodiments of this aspect, each of the signal terminals may be comprised of a mounting portion extending in a first direction and a contact portion extending in a second direction, the second direction being perpendicular to the first direction. The mounting portions of the signal terminals may be configured to be attached to the circuit board, and the contact portions of the signal terminals may be configured to contact corresponding signal terminals of the mating connector when the electrical connector and the mating connector are in the mated position. In some embodiments, the contact portions of the signal terminals may be arranged in an array comprised of a plurality of columns aligned perpendicular to the bottom surface of the housing and a plurality of rows aligned parallel to the bottom surface of the housing. 
     In an aspect, the electrical connector may be a receptacle connector. In some embodiments, the power segments and the signal segments may be configured such that the mating interface of the housing is comprised of protruding engagement section that extends beyond the side surface of housing, and the engagement section of the mating interface is comprised of a plurality of first contact openings through which the power terminals are exposed and a plurality of second contact openings through which the signal terminals are exposed. When the housing is mounted on the circuit board, a mating direction of the electrical connector with the mating connector may be parallel to a surface of the circuit board. The engagement section of the mating interface may be configured to be received in an accommodation space of the mating connector when the electrical connector and the mating connector are in the mated position. 
     In some embodiments of this aspect, the contact portions of the power terminals and the contact portions of the signal terminals may be disposed in the engagement section of the mating interface. The contact portions of the power terminals may be comprised of power tabs. For each of the power terminals, the power tab and the mounting portion may extend in perpendicular directions. In some embodiments, the power segments may be comprised of pairs of first and second power segments, with each of the first power segments being comprised of a first power terminal of the power terminals, and with each of the second power segments being comprised of a second power terminal of the power terminals. For each of the pairs of first and second power segments, a distance in the row direction between a midpoint of the first contact opening corresponding to the first power terminal and a midpoint of the first contact opening corresponding to the second power terminal may be in a range from 2.5 mm to 3.5 mm. For adjacent pairs of the first and second power segments, a distance between the midpoints of the first contact openings corresponding to the first power segments may be in a range from 5.5 mm to 6.5 mm. In some embodiments, for each of the pairs of first and second power segments, a contact surface of the power tab of the first power terminal and a contact surface of the power tab of the second power terminal may face in opposite directions. 
     In some embodiments of this aspect, the power terminals may be arranged in an array comprised of a plurality of columns aligned perpendicular to the bottom surface of the housing and a plurality of rows aligned parallel to the bottom surface of the housing. Each of the power segments may correspond to a column of the array and may be comprised of a first power terminal and a second power terminal of the power terminals. A length of the mounting portions of the first power terminals of the array may be shorter than a length of the mounting portions of the second power terminals of the array. In some embodiments, for each of the power segments, the power tab of the first power terminal may have a curved section that is a mirror image of a curved section of the power tab of the second power terminal. The power tabs of the power terminals may be configured to press against the corresponding power terminals of the mating connector when the electrical connector and the mating connector are in the mated position. In some embodiments, for each of the power segments, a distance in a column direction between a midpoint of the first contact opening corresponding to the first power terminal and a midpoint of the first contact opening corresponding to the second power terminal may be in a range from 1.5 mm to 2.5 mm. In some embodiments, for adjacent pairs of the power segments, a distance in a row direction between the midpoints of the first contact openings corresponding to the first power terminals may be in a range from 6.5 mm to 7.5 mm. In some embodiments, for each of the power segments, a contact surface of the power tab of the first power terminal and a contact surface of the power tab of the second power terminal may face in opposite directions. 
     In some embodiments of this aspect, the contact portions of the signal terminals may be comprised of contact clips, and each of the contact clips may be configured to receive a corresponding signal-pin of the mating connector when the mating connector and the electrical connector are in the mated position. In some embodiments, each of the contact clips of the signal terminals may be comprised of: a first arm comprised of a first contact surface, and a second arm comprised of a second contact surface. For each of the contact clips, the first and second contact surfaces may face each other and may be configured to receive the corresponding signal-pin of the mating connector therebetween, with a distance between the first and second contact surfaces being such that the corresponding signal-pin is pinched by the first and second contact surfaces when the mating connector and the electrical connector are in the mated position. In some embodiments, for each of the signal terminals, the contact clip and the mounting portion may extend in perpendicular directions. In some embodiments, the signal terminals may be arranged such that the contact clips of the signal terminals are disposed in the engagement section of the mating interface in columns and rows such that each of the columns is comprised of the contact clips of at least two of the signal terminals. Each of the signal segments may correspond to a column of the array, and, for each of the signal segments, the mounting portions of the at least two of the signal terminals may have different lengths from each other. In some embodiments, each of the signal segments may be comprised of a first signal terminal and a second signal terminal, and a shape of the mounting portion of the first signal terminal may be different from a shape of the mounting portion of the second signal terminal. 
     In some embodiments of this aspect, each of the mating structures of the first and second end segments may be comprised of a multi-level protrusion configured to be received in a corresponding mating recess of the mating connector when the mating connector and the electrical connector are in the mated position. The engagement section of the mating interface may extend beyond the side surface of the housing by a first distance, and each of the multi-level protrusions may extend beyond the side surface of the housing by a second distance greater than the first distance. In some embodiments, each of the multi-level protrusions may be comprised of a sublevel that extends beyond the side surface of the housing by a third distance less than the second distance and greater than the first distance. In some embodiments, the multi-level protrusions of the first and second end segments may be contiguous with the engagement section of the mating interface. In a mating operation, the multi-level protrusions may be received in the corresponding mating recesses of the mating connector before the engagement section is received in an accommodation space of the mating connector. 
     In another aspect, the electrical connector may be a plug connector. In some embodiments, the side surface of the housing may be an outermost surface of the housing and may be configured to be aligned with the edge of the circuit board such that no part of the housing extends beyond the edge of the circuit board when the first and second end segments are attached to the circuit board. The mating interface of the housing may be comprised of an accommodation space configured to receive a protruding engagement section of the mating connector when the electrical connector and the mating connector are in the mated position. When the first and second end segments are attached to the circuit board, a mating direction of the electrical connector with the mating connector may be parallel to a surface of the circuit board. The contact portions of the power terminals and the contact portions of the signal terminals may be disposed in the accommodation space. 
     In some embodiments of this aspect, for each of the power terminals, the contact portion may be comprised of a set of fingers extending from the body portion in the first direction, with the fingers being configured to press against a corresponding power tab of the mating connector when the mating connector and the electrical connector are in the mated position. For each of the power terminals, the set of fingers and the mounting portion may extend from the body portion in perpendicular directions. In some embodiments, the power segments may be comprised of pairs of first and second power segments, with each of the first power segments being comprised of a first power terminal of the power terminals, and with each of the second power segments being comprised of a second power terminal of the power terminals. For each of the pairs of first and second power segments, a distance in the row direction between a midpoint of the first power segment and a midpoint of the second power segment may be in a range from 2.5 mm to 3.5 mm. For adjacent pairs of first and second power segments, a distance between the midpoints of the first power segments may be in a range from 5.5 mm to 6.5 mm. In some embodiments, for each of the pairs of first and second power segments, a contact surface of the set fingers of the first power terminal and a contact surface of the set fingers of the second power terminal may face in opposite directions. 
     In some embodiments of this aspect, the power terminals may be arranged in an array comprised of a plurality of columns aligned perpendicular to the bottom surface of the housing and a plurality of rows aligned parallel to the bottom surface of the housing. Each of the power segments may correspond to a column of the array and may be comprised of a first power terminal and a second power terminal of the power terminals. A length of the mounting portions of the first power terminals of the array may be shorter than a length of the mounting portions of the second power terminals of the array. In some embodiments, for each of the power segments, the set of fingers of the first power terminal may have a curved section that is a mirror image of a curved section of the set of fingers of the second power terminal. The fingers of the power terminals may be configured to press against the corresponding power terminals of the mating connector when the electrical connector and the mating connector are in the mated position. In some embodiments, for each of the power segments, a distance in a column direction between a midpoint of the body portion of the first power terminal and a midpoint of the body portion of the second power terminal may be in a range from 1.5 mm to 2.5 mm. In some embodiments, for adjacent pairs of the power segments, a distance in a row direction between the midpoints of the body portions of the first power terminals may be in a range from 6.5 mm to 7.5 mm. In some embodiments, for each of the power segments, a contact surface of the set of fingers of the first power terminal and a contact surface of the set of fingers of the second power terminal may face in opposite directions. 
     In some embodiments of this aspect, the contact portions of the signal terminals may be comprised of contact pins, and each of the contact pins may be configured to be inserted in a corresponding signal clip of the mating connector when the mating connector and the electrical connector are in the mated position. In some embodiments, for each of the signal terminals, the contact pin and the mounting portion may extend in perpendicular directions. In some embodiments, the signal terminals may be arranged such that the contact pins of the signal terminals are disposed in the accommodation space of the mating interface in columns and rows such that each column is comprised of the contact pins of at least two of the signal terminals. Each of the signal segments may correspond to a column of the array. For each of the signal segments, the contact pins of the at least two of the signal terminals may have different lengths from each other. 
     In some embodiments of this aspect, each of the mating structures of the first and second end segments may be comprised of a multi-level recess configured to receive a corresponding mating protrusion of the mating connector when the mating connector and the electrical connector are in the mated position. The accommodation space of the mating interface may extend from the side surface into the housing by a first distance, and each of the multi-level recesses may extend from the side surface into the housing by a second distance greater than the first distance. In some embodiments, each of the multi-level recesses may be comprised of a sublevel that extends from the side surface into the housing by a third distance less than the second distance and greater than the first distance. In some embodiments, the multi-level recesses of the first and second end portions may be contiguous with the accommodation space of the mating interface. In a mating operation, the multi-level recesses may receive the corresponding mating protrusions of the mating connector before the accommodation space receives the engagement section of the mating connector. 
     In another aspect, the electrical connector may be a plug connector. Each of the power terminals may be comprised of: a body portion, a mounting portion extending in a first direction from the body portion and configured to be attached to the circuit board, and a contact portion extending in a second direction from the body portion and configured to contact a corresponding power terminal of the mating connector when the electrical connector and the mating connector are in the mated position, the second direction being opposite to the first direction. Each of the signal terminals may be comprised of: a mounting portion extending in the first direction and configured to be attached to the circuit board, and a contact portion extending in the second direction and configured to contact a corresponding signal terminal of the mating connector when the electrical connector and the mating connector are in the mated position. The mating interface of the housing may be comprised of an accommodation space configured to receive a protruding engagement section of the mating connector when the electrical connector and the mating connector are in the mated position. When the first and second end segments are attached to the circuit board, a mating direction of the electrical connector with the mating connector may be perpendicular to a surface of the circuit board. The contact portions of the power terminals and the contact portions of the signal terminals may be disposed in the accommodation space. 
     In some embodiments of this aspect, when the first and second end segments are attached to the circuit board, the side surface of the housing may face a surface of the circuit board, a mating surface of the housing may face away from the surface of the circuit board, and top and bottom surfaces of the housing may be perpendicular to the circuit board. A height of the housing, extending perpendicularly from the bottom surface of the housing to the top surface of the housing, may be in a range from 5.0 mm to 14.0 mm. 
     In some embodiments of this aspect, for each of the power terminals, the contact portion may be comprised of a set of fingers extending from the body portion in the first direction, with the fingers being configured to press against a corresponding power tab of the mating connector when the mating connector and the electrical connector are in the mated position. In some embodiments, for each of the power terminals, the set of fingers and the mounting portion may extend from the body portion in opposite directions. In some embodiments, the power segments may be comprised of pairs of first and second power segments, with each of the first power segments being comprised of a first power terminal of the power terminals, and with each of the second power segments being comprised of a second power terminal of the power terminals. For each of the pairs of first and second power segments, a distance in the row direction between a midpoint of the first power segment and a midpoint of the second power segment may be in a range from 2.5 mm to 3.5 mm. In some embodiments, for adjacent pairs of the first and second power segments, a distance between the midpoints of the first power segments may be in a range from 5.5 mm to 6.5 mm. In some embodiments, for each of the pairs of first and second power segments, a contact surface of the set of fingers of the first power terminal and a contact surface of the set of fingers of the second power terminal face in opposite directions. 
     In some embodiments of this aspect, the power terminals may be arranged in an array comprised of a plurality of columns aligned perpendicular to the bottom surface of the housing and a plurality of rows aligned parallel to the bottom surface of the housing. Each of the power segments may correspond to a column of the array and may be comprised of a first power terminal and a second power terminal of the power terminals. A length of the mounting portions of the first power terminals of the array may be shorter than a length of the mounting portions of the second power terminals of the array. In some embodiments, for each of the power segments, the set of fingers of the first power terminal may have a curved section that is a mirror image of a curved section of the set of fingers of the second power terminal. The fingers of the power terminals may be configured to press against power tabs of the corresponding power terminals of the mating connector when the electrical connector and the mating connector are in the mated position. In some embodiments, for each of the power segments, a distance in a column direction between a midpoint of the body portion of the first power terminal and a midpoint of the body portion of the second power terminal may be in a range from 1.5 mm to 2.5 mm. In some embodiments, a distance in a row direction between midpoints of the body portions of the first power terminals of an adjacent pair of the power segments may be in a range from 6.5 mm to 7.5 mm. In some embodiments, for each of the power segments, a contact surface of the fingers of the first power terminal and a contact surface of the fingers of the second power terminal may face in opposite directions. 
     In some embodiments of this aspect, the contact portions of the signal terminals may be comprised of contact pins, and each of the contact pins may be configured to be inserted in a corresponding signal clip of the mating connector when the mating connector and the electrical connector are in the mated position. In some embodiments, for each of the signal terminals, the contact pin and the mounting portion may extend in opposite directions. In some embodiments, the signal terminals may be arranged such that the contact pins of the signal terminals are disposed in the accommodation space of the mating interface in an array of columns and rows such that each column is comprised of contact pins of at least two of the signal terminals. Each of the signal segments may correspond to a column of the array. 
     In some embodiments of this aspect, each of the mating structures of the first and second end segments may be comprised of a multi-level recess configured to receive a corresponding mating protrusion of the mating connector when the mating connector and the electrical connector are in the mated position. The accommodation space of the mating interface may extend from the mating surface into the housing by a first distance, and each of the multi-level recesses may extend from the mating surface into the housing by a second distance greater than the first distance. In some embodiments, each of the multi-level protrusions may be comprised of a sublevel that extends from the mating surface into the housing by a third distance less than the second distance and greater than the first distance. In some embodiments, the multi-level recesses of the first and second end portions may be contiguous with the accommodation space of the mating interface. In a mating operation, the multi-level recesses may receive the corresponding mating protrusions of the mating connector before the accommodation space receives the engagement section of the mating connector. 
     The foregoing features may be used, separately or together in any combination, in any of the embodiments discussed herein. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Various aspects and embodiments of the present technology disclosed herein are described below with reference to the accompanying figures. It should be appreciated that the figures are not necessarily drawn to scale. Items appearing in multiple figures may be indicated by the same reference numeral. For the purposes of clarity, not every component may be labeled in every figure. 
         FIG.  1    is an elevational side view of an exemplary embodiment of a right-angle receptacle connector and an exemplary embodiment of a right-angle plug connector in a mated position and mounted on respective circuit boards. 
         FIG.  2    is an elevational side view of the right-angle receptacle connector of  FIG.  1    and an exemplary embodiment of a vertical plug connector in a mated position and mounted on respective circuit boards. 
         FIG.  3    is a perspective top front view of the receptacle connector of  FIG.  1    mounted on the circuit board. 
         FIG.  4    is a perspective top front view of the plug connector of  FIG.  1    mounted on the circuit board. 
         FIG.  5    is a perspective top front view of the receptacle connector of  FIG.  1    in a partially disassembled state. 
         FIG.  6 A  is a perspective top front view of the receptacle connector of  FIG.  1   . 
         FIG.  6 B  is an elevational side view of the receptacle connector of  FIG.  1   . 
         FIG.  6 C  is a perspective bottom front view of the receptacle connector of  FIG.  1   . 
         FIG.  6 D  is an elevational front view of the receptacle connector of  FIG.  1   . 
         FIGS.  7 A and  7 B  are an elevational front view and a perspective top front view of an exemplary embodiment of a pair of power segments of the receptacle connector of  FIG.  1   . 
         FIG.  7 C  is a perspective bottom front view of the pair of power segments of  FIG.  7 A  in a partially disassembled state. 
         FIG.  7 D  is a perspective top front view of an exemplary embodiment of a pair of power terminals of the pair of power segments of  FIG.  7 A . 
         FIGS.  8 A and  8 B  are an elevational front view and a perspective top front view of an exemplary embodiment of a signal segment of the receptacle connector of  FIG.  1   . 
         FIG.  8 C  is a perspective bottom front view of the signal segment of  FIG.  8 A  in a partially disassembled state. 
         FIG.  8 D  is a perspective top rear view of an exemplary embodiment of signal terminals of the signal segment of  FIG.  8 A . 
         FIGS.  9 A and  9 B  are an elevational front view and a perspective top front view of an exemplary embodiment of an end segment of the receptacle connector of  FIG.  1   . 
         FIG.  9 C  is a perspective bottom front view of an exemplary embodiment of a housing portion of the end segment of  FIG.  9 A . 
         FIG.  9 D  is a perspective top view of an exemplary embodiment of a retainer clip of the end segment of  FIG.  9 A . 
         FIG.  10    is a perspective top front view of the plug connector of  FIG.  1    in a partially disassembled state. 
         FIG.  11 A  is a perspective top front view of the plug connector of  FIG.  1   . 
         FIG.  11 B  is an elevational side view of the plug connector of  FIG.  1   . 
         FIG.  11 C  is a perspective bottom front view of the plug connector of  FIG.  1   . 
         FIG.  11 D  is an elevational front view of the plug connector of  FIG.  1   . 
         FIGS.  12 A and  12 B  are an elevational front view and a perspective top front view of an exemplary embodiment of a pair of power segments of the plug connector of  FIG.  1   . 
         FIG.  12 C  is a perspective bottom front view of the pair of power segments of  FIG.  12 A  in a partially disassembled state. 
         FIG.  12 D  is a perspective top rear view of an exemplary embodiment of a pair of power terminals of the pair of power segments of  FIG.  12 A . 
         FIGS.  13 A and  13 B  are an elevational front view and a perspective top front view of an exemplary embodiment of a signal segment the plug connector of  FIG.  1   . 
         FIG.  13 C  is a perspective top front view of the signal segment of  FIG.  13 A  in a partially disassembled state. 
         FIGS.  14 A and  14 B  are an elevational front view and a perspective top front view of an exemplary embodiment of an end segment of the plug connector of  FIG.  1   . 
         FIG.  14 C  is a perspective bottom front view of an exemplary embodiment of a housing portion of the end segment of  FIG.  14 A . 
         FIG.  14 D  is a perspective top view of an exemplary embodiment of a retainer clip of the end segment of  FIG.  14 A . 
         FIG.  15    is a perspective side view of the vertical plug connector of  FIG.  2    in a partially disassembled state. 
         FIG.  16 A  is a perspective top view of the plug connector of  FIG.  2   . 
         FIG.  16 B  is an elevational side view of the plug connector of  FIG.  2   . 
         FIG.  16 C  is a plan top view of the plug connector of  FIG.  2   . 
         FIG.  16 D  is an elevational side view of the plug connector of  FIG.  2   . 
         FIGS.  17 A and  17 B  are a plan top view and a perspective top view of an exemplary embodiment of a pair of power segments of the plug connector of  FIG.  2   . 
         FIG.  17 C  is a perspective top view of the pair of power segments of  FIG.  17 A  in a partially disassembled state. 
         FIG.  17 D  is a perspective top view of an exemplary embodiment of a pair of power terminals of the pair of power segments of  FIG.  17 A . 
         FIGS.  18 A and  18 B  are a plan top view and a perspective top view of an exemplary embodiment of a signal segment of the plug connector of  FIG.  2   . 
         FIG.  18 C  is a perspective top view of the signal segment of  FIG.  18 A  in a partially disassembled state. 
         FIG.  19 A  is a plan top view of an exemplary embodiment of an end segment of the plug connector of  FIG.  2   . 
         FIG.  19 B  is a perspective view of an exemplary embodiment of an external side of the end segment of  FIG.  19 A . 
         FIG.  19 C  is a perspective view of an exemplary embodiment of an internal side of the end segment of  FIG.  19 A  in a partially disassembled state. 
         FIG.  20 A  is an elevational front view of an exemplary embodiment of a receptacle connector. 
         FIG.  20 B  is an elevational front view of an exemplary embodiment of two “stacked” power segments of the receptacle connector of  FIG.  20 A . 
         FIG.  21    is an elevational front view of an exemplary embodiment of four “in-line” power segments of a receptacle connector. 
     
    
    
     DETAILED DESCRIPTION 
     The inventors have recognized and appreciated design techniques for connectors that may ease the burden of connector selection and qualification. These techniques may enable connectors that may be easily configured for any of a number of applications with consistent mating interfaces and other properties. Designers of electronic devices may develop a design using a connector of one configuration and easily and confidently adapt their design to use a connector, based on the same design techniques, for another configuration, which eases the burden of selection and qualification. As one example, the design techniques may facilitate variation in the amount of power carried by a circuit and/or the number of circuits within a connector. 
     The inventors also have recognized and appreciated design techniques for electrical connectors that enable mated plug and receptacle connectors to have a low profile while providing reliable operation for high-integrity electrical interconnects. Techniques and technology described herein may lead to compact and ultra-low-profile connectors able to interconnect two circuit boards via a high density of terminals. As an example, circuit boards on which the electrical connectors are mounted may be oriented edge-to-edge to enable ultra-low-profile “flat” interconnections, which may be advantageous to fit in a narrow flat space. In another example, circuit boards on which the electrical connectors are mounted may be oriented perpendicularly to enable ultra-low-profile corner interconnections, which may be advantageous to fit in a narrow corner space. 
     According to some aspects, a receptacle connector and a plug connector may form a flat board-to-board type of connection configuration. The receptacle connector may be a right-angle connector attached to a first circuit board such that an edge of the first circuit board aligns with a mating surface or interface of the receptacle connector. The plug connector may be a right-angle connector attached to a second circuit board such that an edge of the second circuit board aligns with a mating surface or interface of the receptacle connector. When the receptacle connector and the plug connector are in a mated position, the edges of the first and second circuit boards face each other and may even touch. As will be appreciated, the mating surface of the receptacle connector need not be an outermost surface, and a portion of the connector may protrude beyond the mating surface and may be configured to be inserted in a space of the plug connector. Similarly, the mating surface of the plug connector need not be an outermost surface, and a portion of the connector may protrude beyond the mating surface and may be configured to be inserted in a space of the receptacle connector. 
     According to some aspects, a receptacle connector and a plug connector may form a corner type of connection configuration. The receptacle connector may be a right-angle connector attached to a first circuit board such that at least one edge of the first circuit board aligns with at least one surface of the receptacle connector, respectively. The plug connector may be a vertical connector attached to a second circuit board such that an edge of the second circuit board aligns with at least one surface of the receptacle connector, respectively. When the receptacle connector and the plug connector are in a mated position, an edge of the first circuit board may be aligned with a surface of the receptacle connector forming one side of a corner, and an edge of the second circuit board may be aligned with a surface of the receptacle connector forming another side of the corner. 
     According to some aspects, a connector may have a segmented construction, which may provide flexibility to configure segment, e.g., to obtain a desired number of signal terminals and/or a desired number of power terminals in each connector. In some embodiments, the connector may be comprised of a plurality of segments connected consecutively. For example, the connector may be comprised of a plurality of signal segments and a plurality of power segments aligned in a row. Each power segment may be comprised of one power terminal or a column of two or more power terminals. Similarly, each signal segment may be comprised of one signal terminal or a column of two or more signal terminals. 
     In some embodiments, the segments of the connector may be separately formed and then joined together, such as by fusing an insulative housing of each segment to an insulative housing of an adjacent segment and/or by cementing or gluing each segment to an adjacent segment. Alternatively, insulative portions of the segments may be formed in a mold made up of segments corresponding to the segments of the connector. The mold segments may be held in a common fixture or otherwise held together to create a molded housing with a desired configuration of segments. Corresponding terminals may then be inserted into the segments of the molded housing. In this way, a connector may be formed with an insulative housing holding an array of signal terminals and at least one array of power terminals. 
     Alternatively or additionally, molds may be constructed for molding insulative housings for some or all of the desired connector configurations. Such housings may also have a signal portion and a power portion and any or all of the structures that may result from forming a connector housing from a plurality of segments as described herein. For example, the signal portion may be comprised of signal terminals inserted into the insulative housing and arranged in rows and columns. The power portion may be comprised of a plurality of rows of first power terminals and a plurality of rows of second power terminals inserted into the insulative housing. 
     Turning now to the figures,  FIG.  1    shows a mated pair  1  of electrical connectors mounted on respective circuit boards  3 ,  4  in a board-to-board configuration, according to some embodiments. The mated pair  1  may be comprised of a right-angle receptacle connector  100  mounted on the circuit board  3  and a right-angle plug connector  200  mounted on the circuit board  4 . The connectors  100 ,  200  may be referred to as “right-angle” connectors because mounting portions  5 ,  6  of their power terminals and signal terminals (discussed below) may be oriented generally perpendicular to their mating directions, which are represented in  FIG.  1    by the dashed arrows above each of the connectors  100 ,  200 . In some embodiments, the connector  100  may be configured such that a side surface or edge  7  is aligned with an edge  3 A of the circuit board  3 , and the connector  200  may be configured such that a side surface or edge  8  is aligned with an edge  4 A of the circuit board  4 . In some embodiments, the side surfaces  7 ,  8  may serve as portions of mating interfaces of the connectors  100 ,  200 . With such board-to-board configurations, when the connectors  100 ,  200  are in a mated position, such as depicted in  FIG.  1   , the circuit board  3  of the connector  100  may be aligned parallel with the circuit board  4  of the connector  200  such that their edges  3 A,  4 A face each other and may even touch, in some embodiments. In some embodiments, such configurations may advantageously enable the connectors  100 ,  200  to be supported by the circuit boards  3 ,  4  at or very close their side surfaces  7 ,  8 . The additional rigidity provided by the circuit boards  3 ,  4 , at or near the side surfaces  7 ,  8  may enable, for example, electrical connections between the connectors  100 ,  200  to be robust even under conditions where the mated pair  1  may experience vibrations or shock, which may arise when the mated pair  1  is part of an electronic system that undergoes jostling and/or movement in ordinary use. 
     According to some embodiments, the mated pair  1  may be deployed in an electronic system intended to be portable. Portable systems typically are compact, for ease of handling and to minimize weight, and therefore may have little room for electrical connectors. In situations where a flat, narrow clearance space is available for electrical connections, the board-to-board configuration of the mated pair  1  may be particularly suitable. In some embodiments, a maximum height H 1  of the connectors  100 ,  200  from a first surface  9 A,  10 A facing the circuit board  3 ,  4  to a second surface  9 B,  10 B opposite the first surface  9 A,  10 A may be in a range from 5.0 mm to 14.0 mm (e.g., from 6.0 mm to 12.0 mm, from 6.5 mm to 7.5 mm, from 10.5 mm to 11.5 mm, from 7.0 mm to 9.0 mm). In some embodiments, the height H 1  may have a value of approximately 8.0 mm. Thus, the connectors  100 ,  200  may be considered to have a low profile. 
       FIG.  2    shows a mated pair  2  of electrical connectors comprised of the receptacle connector  100  and a vertically oriented plug connector  300  mounted on respective circuit boards  3 ,  11 . The connector  300  may be referred to as a “vertical” connector because a mounting portion  12  of its power terminals and signal terminals (discussed below) may be oriented generally parallel to its mating direction, which is represented in  FIG.  2    by the dashed arrow above the connector  300 . The connector  300  may be similar to the connector  200  except for the configurations of their power terminals and signal terminals. In some embodiments, the connector  300  may be configured such that a first side surface  13 A is aligned with an edge  11 A of the circuit board  11 . In some embodiments, the first side surface  13 A also may be aligned with the second surface  9 B of the connector  100 , as shown in  FIG.  2   . In some embodiments, the connector  300  may be configured such that a second side surface  13 B is aligned with an edge  11 B of the circuit board  11 . In some embodiments, the second side surface  13 B also may be aligned with the first surface  9 A of the connector  100 , as shown in  FIG.  2   . 
     In some embodiments, the connector  100  may be configured such that a third surface  9 C may be aligned with an edge  3 B of the circuit board  3 , as shown in  FIG.  2   . In some embodiments, the second side surface  13 B also may be aligned with the first surface  9 A of the connector  100 , as shown in  FIG.  2   . Similarly, although not specifically shown in the drawings, the connector  200  may be configured such that a third surface  10 C is aligned with an edge of the circuit board  4  opposite to the edge  4 A. 
     In some embodiments, a height of the connector  300  from the first side surface  13 A to the second side surface  13 B may be the height H 1  of the connector  100 . 
     According to some embodiments, the vertical-to-right-angle configuration of the mated pair  2  may enable the mated pair  2  to provide robust electrical connections in situations where a narrow clearance space is available at a corner of an electronic system. 
       FIG.  3    shows a perspective view of the receptacle connector  100  mounted on the circuit board  3 , according to some embodiments. The connector  100  may have a low profile relative to the circuit board  3  and may be oriented such that a plurality of power terminals (described below) are aligned in a row along a row or X direction. In some embodiments, the connector  100  may have a plurality of rows of power terminals, with the rows being aligned or stacked in a column or Y direction such that the power terminals may be arranged in an array of columns and rows. Similarly, the connector  100  may be comprised of a plurality of signal terminals (described below) arranged in a single row aligned with the X direction or in an array of rows and columns aligned with the X and Y directions. 
     For clarity of illustration, the connectors described herein may be illustrated as multiple segments, aligned side-by-side. Such an illustration reveals that a connector (e.g., the connector  100 ) may have multiple segments of a limited number of types. As noted above, a housing of the connector may be constructed by separately forming and then joining insulative housing portions for these segments or may be formed from one or more sections containing multiple such segments. For example, in some embodiments, a segmented connector may be constructed with a single or unitary insulative power housing structured to accommodate power terminals joined with a single or unitary insulative signal housing structured to accommodate signal terminals. In other embodiments, an entire housing of a connector may be unitarily formed, such as by molding plastic, nylon, or another insulative material. 
       FIG.  4    shows a perspective view of the plug connector  200  mounted on the circuit board  4 , according to some embodiments. The connector  200  may constructed with materials and techniques similar to those used for the connector  100 , with components of the connector  200  being shaped complementarily to corresponding components of connector  100  so that the two connectors mate. The connector  200  may have a low profile relative to the circuit board  4  and may be oriented such that a plurality of power terminals (described below) are aligned in a single row along the X direction or in an array of columns and rows aligned with the X and Y directions. Similarly, the connector  200  may be comprised of a plurality of signal terminals (described below) arranged in a single row aligned with the X direction or in an array of columns and rows aligned with the X and Y directions. The power terminals of the connector  200  may be configured to engage with corresponding power terminals of the connector  100  to transmit power between the connectors  100 ,  200 . Likewise, the signal terminals of the connector  200  may be configured to engage with corresponding signal terminals of the connector  100  to transmit signals between the connectors  100 ,  200 . 
     In  FIGS.  3  and  4   , the arrow A represents the mating direction of the connectors  100 ,  200 . 
     Right-Angle Receptacle Connector 
       FIG.  5    shows the receptacle connector  100  in a partially disassembled state, according to some embodiments.  FIGS.  6 A through  6 D  show, respectively, a perspective top front view, an elevational side view, a perspective bottom front view, and an elevational front view of the receptacle connector  100 , according to some embodiments. The connector  100  may be comprised of an insulative housing  102 , a plurality of electrically conductive power terminals  130 , a plurality of electrically conductive signal terminals  160 , and at least two hold-down clips  190 . Each of the terminals  130 ,  160  and the hold-down clips  190  may be disposed at least partially in the housing  102 . Each of the terminals  130 ,  160  and the clips  190  may have a mounting portion configured to mount to the circuit board  3 . In some embodiments, the circuit board  3  may be comprised of holes configured to receive the mounting portions of the terminals  130 ,  160  and the clips  190 , which may be fixedly attached to the circuit board  3 . The power terminals  130  and the signal terminals  160  may be formed of metal or another material having high electrical conductivity, and may be fixed to the circuit board by, e.g., soldering, although attachment techniques other than soldering may be used. The hold-down clips  190  may be formed of metal, which may enable soldering of the clips  190  to the circuit board  3 , or the clips  190  may be formed of a hard plastic or another material having high stiffness and configured to engage in or latch to corresponding holes in the circuit board  3  through an interference fit other than soldering. 
     According to some embodiments, contact portions of the power terminals  130  and contact portions of the signal terminals  160  may be exposed through contact openings  132 ,  162  in an engagement protrusion  110  of the housing  102 . The engagement protrusion  110  may be configured to be received in a corresponding engagement portion (e.g., an accommodation space) of a mating connector (e.g., the plug connector  200 ,  300 ) when the connector  100  and the mating connector are mated together. In some embodiments, the engagement protrusion  110  may be part of the mating interface of the connector  100  and may protrude from the side surface  7  of the connector  100 , as depicted in  FIG.  6 B . In some embodiments, the contact portions of the power terminals  130  and the signal terminals  160  may extend in the mating direction A into the engagement protrusion  110 , and mounting legs of the power terminals  130  and the signal terminals  160  may extend in the Y direction perpendicular to the mating direction A. 
     According to some embodiments, the connector  100  may be comprised of a power portion  104  and a signal portion  106  sandwiched between two end portions  108 , as shown in  FIG.  6 A . In some embodiments, a spacer portion may separate the power portion  104  from the signal portion  106 . Each of the end portions  108  may be comprised of an alignment structure configured to facilitate proper alignment of the connector  100  with a mating connector (e.g., the connector  200 ,  300 ). In some embodiments, the alignment structure may be a multi-level protrusion  112  comprised of a first portion  112   a  that extends from the side surface  7  by a first distance and a second portion  112   b  that extends from the side surface  7  by a second distance greater than the first distance. In some embodiments, the first and second portions  112   a ,  112   b  may be shaped to facilitate seating of the first and second portions  112   a ,  112   b  in corresponding recesses in a mating connector. For example, each of the first and second portions may be comprised of any one or any combination of: a bevel, a curve, a slope, etc. In some embodiments, the first portions  112   a  may be the outermost portions of the housing  102  in the X direction. Although not depicted in  FIGS.  6 A through  6 C , each of the end portions  108  may be attached to the circuit board  3  by at least one of the hold-down clips  190 . In some embodiments, the clips  190  may have a U-shaped structure configured to clip the end portions  108  to the circuit board  3 . The end portions  108  may be structured to have the same configuration with opposite orientations, such that they may be mirror images of each other. 
     According to some embodiments, the connector  100  may have a segmented construction. That is, the connector  100  may be formed of segments joined together to form the housing  102 , with the terminals  130 ,  160  and the hold-down clips  190  being disposed at least partially in the segments. In some embodiments, the power portion  104  may be comprised of a plurality of power segments  104 A,  104 B joined together, the signal portion  106  may be comprised of a plurality of signal segments  106 A joined together, and each of the end portions  108  may be comprised of an end segment  108 A. In some embodiments, the power segments  104 A,  104 B may alternate in the X direction and may be grouped as pairs  104 AB, as depicted in  FIGS.  6 C and  6 D . 
     According to some embodiments, the power portion  104  of the connector  100  may be comprised of twelve power terminals  130 A,  130 B spanning a distance X 1 , as depicted in  FIG.  6 D . In some embodiments, the distance X 1  may be in a range from 30 mm to 40 mm (e.g., 32 mm to 38 mm). In some embodiments, the distance X 1  may have a value of approximately 36 mm, with an average distance of 3 mm for each of the power terminals  130 A,  130 B. In some embodiments, the height H 1  may have a value of approximately 8 mm. Thus, an area of a front face of the power portion (X 1 ×H 1 ) may be approximately 288 mm 2 , in some embodiments. In some embodiments, a height of the engagement protrusion  110  may be in a range from 5 mm to 7 mm, and a typical value for this height may be approximately 6 mm. Therefore, an area of a front face of a power section of the engagement protrusion  110  may be approximately 216 mm 2 , in some embodiments. 
     According to some embodiments, the signal portion  106  of the connector  100  may be comprised of ten signal terminals  160 A,  160 B spanning a distance X 2 , as depicted in  FIG.  6 D . In some embodiments, the distance X 2  may be in a range from 10 mm to 15 mm (e.g., 11 mm to 14 mm). In some embodiments, the distance X 2  may have a value of approximately 12.5 mm, with an average distance of 2.5 mm for each column of two power terminals  160 A,  160 B. Therefore, in some embodiments, an area of a front face of the signal portion (X 2 ×H 1 ) may be approximately 100 mm 2 , and an area of a front face of a signal section of the engagement protrusion  110  may be approximately 75 mm 2 . 
       FIG.  7 A  shows an elevational front view of the power segments  104 A,  104 B grouped as a pair  104 AB, according to some embodiments, and  FIG.  7 B  shows a perspective top front view of the pair  104 AB.  FIG.  7 C  shows a perspective bottom front view of the pair  104 AB in a partially disassembled state. The power segments  104 A,  104 B may be aligned in the X direction and may be arranged in an alternating pattern. In some embodiments, each of the power segments  104 A may be comprised of a conductive power terminal  130 A attached to an insulative housing portion  102 A. The power terminal  130 A may be comprised of a body portion  130   a , a contact portion  130   b , and a mounting portion  130   c . The mounting portion  130   c  may be comprised of one or more legs extending from the body portion  130   a  in the Y direction, and the contact portion  130   b  may be comprised of a power tab extending from the body portion  130   a  in the mating direction A perpendicular to the Y direction. As can be seen in  FIGS.  7 A through  7 D , the contact portion (power tab)  130   b  may have a plate-like form. In some embodiments, the contact portions (power tabs)  130   b  of the power segments  104 A may be vertically oriented such that their contact surfaces may be aligned with the Y direction. 
     The contact portion  130   b  may be disposed in an engagement portion  110 A protruding from the side surface  7  such that the contact portion  130   b  may contact a corresponding contact portion of a mating connector via the contact hole  132  of the power segment  104 A. The mounting portion  130   c  may comprise part of the mounting portion  5  of  FIG.  1   . 
     According to some embodiments, each of the power segments  104 B may be comprised of a conductive power terminal  130 B attached to an insulative housing portion  102 B. The power terminal  130 B may be comprised of a body portion  130   a , a contact portion  130   b , and a mounting portion  130   c , similar to the power terminal  130 A. In some embodiments, the power segment  104 B may be the same as the power segment  104 A. In some other embodiments, the power segment  104 B may be a mirror image of the power segment  104 A, as depicted in  FIG.  7 A . In such mirror-image embodiments, the power terminals  130 A,  130 B may be comprised of respective curved sections  130   d  that are mirror images of each other, as depicted in the perspective view of  FIG.  7 D . 
       FIG.  8 A  shows an elevational front view of the signal segment  106 A, according to some embodiments, and  FIG.  8 B  shows a perspective top front view of the signal segment  106 A.  FIG.  8 C  shows a perspective bottom front view of the signal segment  106 A in a partially disassembled state. In some embodiments, the signal segment  106 A may be comprised of first and second conductive signal terminals  160 A,  160 B attached to an insulative housing portion  102 C. Each of the first and second signal terminals  160 A,  160 B may be comprised of a contact portion  160   b , a mounting portion  160   c , and a right-angle connector portion  160   d  connecting the contact portion  160   b  and the mounting portion  160   c . The mounting portion  160   c  may be comprised of a leg extending from the connector portion  160   d  in the Y direction, and the contact portion  160   b  may be comprised of a contact clip extending from the connector portion  160   d  in the mating direction A perpendicular to the Y direction. The first and second signal terminals  160 A,  160 B may be arranged in the housing portion  102 C such that their contact portions  160   b  are aligned or stacked in a column in the Y direction. The contact portions  160   b  of the first and second signal terminals  160 A,  160 B may be disposed in an engagement portion  110 B of the housing portion  102 C protruding from the side surface  7  such that the contact portions  160   b  may contact corresponding contact portions of a mating connector via the contact holes  162  of the signal segment  106 A. The mounting portions  160   c  may comprise part of the mounting portion  5  of  FIG.  1   . In some embodiments, the connector portion  160   d  of the first signal terminal  160 A may have a different structure from that of the connector portion  160   d  of the second signal terminal  160 B. For example, the connector portion  160   d  of the first signal terminal  160 A may have a longer total length compared to a total length of the connector portion  160   d  of the second signal terminal  160 B, as shown in  FIG.  8 D . In another example, the connector portion  160   d  of the first signal terminal  160 A may have a different edge contour from that of the connector portion  160   d  of the second signal terminal  160 A, as shown in  FIG.  8 D . In a further example (not shown), the mounting portions  160   c  of the first and second signal terminals  160 A,  160 B may have a different appearance from each other. 
     According to some embodiments, each of the contact portions  160   b  of the first and second signal terminals  160 A,  160 B may be comprised of a contact clip having a pair of contact surfaces extending from the connector portion  160   d  via a pair of arms, as shown in  FIG.  8 D . The contact clip may resemble a pair of tweezers, in some embodiments, and may be configured to grasp or pinch a corresponding contact terminal (e.g., a contact pin) of a mating connector when the connector  100  and the mating connector are in a mated position. 
       FIGS.  9 A and  9 B  show an elevational front view and a perspective top front view of one of the end segments  108 A, according to some embodiments. As noted above, the end segments  108 A may be located on opposite ends of the connector  100  sandwiching the power segments  104 A,  104 B and the signal segments  106 A in between. As will be appreciated, the other one of the end segments  108 A may be a mirror image of the one shown in  FIG.  9 A  and therefore will not be described separately. In some embodiments, the end segment  108 A may be comprised of an insulative housing portion  102 D to which at least one of the hold-down clips  190  is attached.  FIG.  9 C  shows a perspective bottom front view of the housing portion  102 D. For example, a mounting portion  190   c  of the hold-down clip  190  may extend through a recess  102   d  of the housing portion  102 D. In some embodiments, the hold-down clip  190  may be a retainer clip comprised of a plurality of legs ( 190   c ) extending from a bridge ( 190   a ), as depicted in  FIG.  9 D . In some embodiments, the hold-down clip  190  may be attached to the housing portion  102 D such that the legs forming the mounting portion  190   c  extend from the housing portion  102 D in the Y direction. The end segment  108 A may have an alignment structure similar to that described above for the end portion  108 , and therefore will not be described separately. 
     Right-Angle Plug Connector 
     Turning now to the plug connector  200 ,  FIG.  10    shows the connector  200  in a partially disassembled state, according to some embodiments.  FIGS.  11 A through  11 D  show, respectively, a perspective top front view, an elevational side view, a perspective bottom front view, and an elevational front view of the connector  200 , according to some embodiments. The connector  200  may be comprised of an insulative housing  202 , a plurality of electrically conductive power terminals  230 , a plurality of electrically conductive signal terminals  260 , and at least two hold-down clips  290 . Each of the terminals  230 ,  260  and the hold-down clips  290  may be disposed at least partially in the housing  202 . Each of the terminals  230 ,  260  and the clips  290  may have a mounting portion configured to mount to the circuit board  4 . In some embodiments, the circuit board  4  may be comprised of holes configured to receive the mounting portions of the terminals  230 ,  260  and the clips  290 , which may be fixedly attached to the circuit board  4 . The power terminals  230  and the signal terminals  260  may be formed of metal or another material having high electrical conductivity, and may be fixed to the circuit board  4  by, e.g., soldering, although attachment techniques other than soldering may be used. The hold-down clips  290  may be formed of metal, which may enable soldering of the clips  290  to the circuit board  4 , or the clips  290  may be formed of a hard plastic or another material having high stiffness and configured to engage in or latch to corresponding holes in the circuit board  4  through an interference fit other than soldering. 
     According to some embodiments, contact portions of the power terminals  230  and contact portions of the signal terminals  260  may be disposed in an engagement space  210  of the housing  202 . The engagement space  210  may be an accommodation space configured to receive a corresponding engagement portion (e.g., an engagement protrusion) of a mating connector (e.g., the receptacle connector  100 ) when the connector  200  and the mating connector are mated together. In some embodiments, the engagement space  210 , which may be part of the mating interface of the connector  200 , may be a cavity in the housing  202  and may extend into the housing  202  from the side surface  8  of the connector  200 , as depicted in  FIG.  11 B . In some embodiments, the contact portions of the power terminals  230  and the signal terminals  260  may extend in the mating direction A into the engagement space  210 , and the mounting portions of the power terminals  230  and the signal terminals  260  may extend in the Y direction perpendicular to the mating direction A. 
     According to some embodiments, the connector  200  may be comprised of a power portion  204  and a signal portion  206  sandwiched between two end portions  208 , as shown in  FIG.  11 A . Each of the end portions  208  may be comprised of an alignment structure configured to facilitate proper alignment of the connector  200  with a mating connector (e.g., the connector  100 ). In some embodiments, the alignment structure may be a multi-level recess  212  comprised of a first portion that  212   a  that extends from the surface  8  into the housing  202  by a first distance and a second portion  212   b  that extends from the side surface  8  into the housing  202  by a second distance greater than the first distance. In some embodiments, the first and second portions  212   a ,  212   b  of the recess  212  may be shaped to facilitate seating of a corresponding multi-level mating protrusion of a mating connector. For example, each of the first and second portions  212   a ,  212   b  may be comprised of any one or any combination of: a bevel, a curve, a slope, etc. 
     Although not depicted in  FIGS.  11 A through  11 C , each of the end portions  208  may be attached to the circuit board  4  by at least one of the hold-down clips  290 . In some embodiments, the hold-down clips  290  may have a U-shaped structured configured to clip the end portions  208  to the circuit board  4 . 
     According to some embodiments, the connector  200  may have a segmented construction. That is, the connector  200  may be formed of segments joined together to form the housing  202 , with the terminals  230 ,  260  and the hold-down clips  290  being disposed at least partially in the housing  202 . In some embodiments, the power portion  204  may be comprised of a plurality of power segments  204 A,  204 B joined together, the signal portion  206  may be comprised of a plurality of signal segments  206 A joined together, and each of the end portions  208  may be comprised of an end segment  208 A. In some embodiments, the power segments  204 A,  204 B may alternate in the X direction and may be grouped as pairs  204 AB, as depicted in  FIGS.  11 C and  11 D . 
       FIG.  12 A  shows an elevational front view of the power segments  204 A,  204 B grouped as a pair  204 AB, according to some embodiments, and  FIG.  12 B  shows a perspective top front view of the pair  204 AB.  FIG.  12 C  shows a perspective bottom front view of the pair  204 AB in a partially disassembled state. The power segments  204 A,  204 B may be aligned in the X direction and may be arranged in an alternating pattern. In some embodiments, each of the power segments  204 A may be comprised of a conductive power terminal  230 A attached to an insulative housing portion  202 A. The power terminal  230 A may be comprised of a body portion  230   a , a contact portion  230   b , and a mounting portion  230   c . The mounting portion  230   c  may be comprised of one or more legs extending from the body portion  230   a  in the Y direction, and the contact portion  230   b  may be comprised of fingers extending from the body portion  230   a  in the mating direction A perpendicular to the Y direction. The contact portion  230   b  may be disposed in an engagement space  210 A extending into the housing portion  202 A from the side surface  8  such that the contact portion  230   b  may contact a corresponding contact portion of a mating connector when the connector  200  and the mating connector are in a mated position. The mounting portion  230   c  may comprise part of the mounting portion  6  of  FIG.  1   . In some embodiments, each of the power segments  204 B may be comprised of a conductive power terminal  230 B attached to an insulative housing portion  202 B. The power terminal  230 B may be comprised of a body portion  230   a , a contact portion  230   b , and a mounting portion  230   c , similar to the power terminal  230 A, with the contact portion  230   b  being disposed in an engagement space  210 B of the power terminal  230 B. In some embodiments, the power segment  204 B may be the same as the power segment  204 A. In some embodiments, the power segments  204 B and the power segments  204 A may be mirror images of each other. In some embodiments, the power terminals  230 A,  230 B may have respective curved sections  230   d  that are mirror images of each other, as depicted in  FIG.  12 D . 
       FIG.  13 A  shows an elevational front view of the signal segment  206 A, according to some embodiments, and  FIG.  13 B  shows a perspective top front view of the signal segment  206 A.  FIG.  13 C  shows a perspective front view of the signal segment  206 A in a partially disassembled state. In some embodiments, the signal segment  206 A may be comprised of first and second conductive signal terminals  260 A,  260 B attached to an insulative housing portion  202 C. Each of the first and second signal terminals  260 A,  260 B may be comprised of a contact portion  260   b , a mounting portion  260   c , and a right-angle connector portion  260   d  connecting the contact portion  260   b  and the mounting portion  260   c . The mounting portion  260   c  may be comprised of a leg extending from the connector portion  260   d  in the Y direction, and the contact portion  260   b  may be comprised of a contact pin extending from the connector portion  260   d  in the mating direction A perpendicular to the Y direction. The first and second signal terminals  260 A,  260 B may be arranged in the housing portion  202 C such that their contact portions  260   b  are aligned or stacked in a column in the Y direction. The contact portions  260   b  of the first and second signal terminals  260 A,  260 B may be disposed in an engagement space  210 B of the housing portion  202 C and may extend into the housing portion  202 C from the side surface  8  such that the contact portions  260   b  may contact corresponding contact portions of a mating connector. The mounting portions  260   c  may comprise part of the mounting portions  6  of  FIG.  1   . In some embodiments, the connector portion  260   d  of the first signal terminal  260 A may have a different structure from that of the connector portion  260   d  of the second signal terminal  260 B. For example, the connector portion  260   d  of the first signal terminal  260 A may have a longer total length compared to a total length of the connector portion  260   d  of the second signal terminal  260 B, as shown in  FIG.  13 D . 
       FIG.  14 A  shows an elevational front view of one of the end segments  208 A, according to some embodiments. As noted above, the end segments  208 A may be located on opposite ends of the connector  200  sandwiching the power segments  204 A,  204 B and the signal segments  206 A in between. As will be appreciated, the other one of the end segments  208 A may be a mirror image of the one shown in  FIG.  14 A  and therefore will not be described separately. In some embodiments, the end segment  208 A may be comprised of an insulative housing portion  202 D to which at least one of the hold-down clips  290  is attached.  FIGS.  14 B and  14 C  show, respectively, a perspective top front view and a perspective bottom front view of the housing portion  202 D. For example, a mounting portion  290   c  of the hold-down clip  290  may extend through a recess  202   d  of the housing portion  202 D. In some embodiments, the hold-down clip  290  may be a U-shaped retainer clip comprised of a plurality of legs ( 290   c ) extending from a bridge ( 290   a ), as depicted in  FIG.  14 D . In some embodiments, the hold-down clip  290  may be attached to the housing portion  202 D such that the legs forming the mounting portion  290   c  extend from the housing portion  202 D in the Y direction. The end segment  208 A may have the same alignment structure as that described above for the end portion  208 . That is, in some embodiments, the alignment structure of the end segment  208 A may be comprised of the first and second portions  212   a ,  212   b  forming the multi-level recess  212 , which may extend from the side surface  8  into the housing  202 D. In some embodiments, a depth of the second portion  212   b  as measured from the side surface  8  may be greater than a depth of the first portion  212   a  from the side surface  8 . 
     According to some embodiments, the engagement spaces  210 A,  210 B,  210 C of the power segments  204 A,  204 B and the signal segments  206 A may be contiguous with each other to form the accommodation space  210  of the housing  200 , as shown in  FIGS.  10  and  11 C . In some embodiments, the accommodation space  210  may be comprised of the multilevel recesses  212  of the end segments  208 A such that the engagement spaces  210 A,  210 B,  210 C and the multilevel recesses  212  form a contiguous cavity in the housing  200 . 
     Vertical Plug Connector 
     Turning now to the vertical plug connector  300 ,  FIG.  15    shows the connector  300  in a partially disassembled state, according to some embodiments.  FIGS.  16 A through  16 D  show, respectively, a perspective top view, an elevational side view, a plan top view, and an elevational side view of the connector  300 , according to some embodiments. The connector  300  may be comprised of an insulative housing  302 , a plurality of electrically conductive power terminals  330 , a plurality of electrically conductive signal terminals  360 , and at least two hold-down clips  390 . Each of the terminals  330 ,  360  and the hold-down clips  390  may be disposed at least partially in the housing  302 .**Each of the terminals  330 ,  360  and the clips  390  may have a mounting portion configured to mount to the circuit board  11 . In some embodiments, the circuit board  11  may be comprised of holes configured to receive the mounting portions of the terminals  330 ,  360  and the clips  390 , which may be fixedly attached to the circuit board  11 . The power terminals  330  and the signal terminals  360  may be formed of metal or another material having high electrical conductivity, and may be fixed to the circuit board  11  by, e.g., soldering, although attachment techniques other than soldering may be used. The hold-down clips  390  may be formed of metal, which may enable soldering of the clips  390  to the circuit board  11 , or the clips  390  may be formed of a hard plastic or another material having high stiffness and configured to engage in or latch to corresponding holes in the circuit board  11  through an interference fit other than soldering. 
     According to some embodiments, contact portions of the power terminals  330  and contact portions of the signal terminals  360  may be disposed in an engagement space  310  of the housing  302 . The engagement space  310 , which may be part of the mating interface of the connector  300 , may be an accommodation space configured to receive a corresponding engagement portion (e.g., an engagement protrusion) of a mating connector (e.g., the receptacle connector  100 ) when the connector  300  and the mating connector are mated together. In some embodiments, the engagement space  310  may be a cavity in the housing  302  and may extend into the housing  302  from a side surface or edge  14  of the connector  300 , as depicted in  FIGS.  16 A and  16 B . The side surface  14  may be part of a mating interface of the connector  300 . In some embodiments, the contact portions of the power terminals  330  and the signal terminals  360  may extend in the mating direction A into the engagement space  310 , and the mounting portions  12  of the power terminals  330  and the signal terminals  360  may extend in a Z direction parallel to the mating direction A. 
     According to some embodiments, the connector  300  may be comprised of a power portion  304  and a signal portion  306  sandwiched between two end portions  308 , as shown in  FIG.  16 A . Each of the end portions  308  may be comprised of an alignment structure configured to facilitate proper alignment of the connector  300  with a mating connector (e.g., the connector  100 ). In some embodiments, the alignment structure may be a multi-level recess similar to the multi-level recess  212  of the connector  200 , discussed above, and therefore will not be described separately. 
     According to some embodiments, the connector  300  may have a segmented construction and may be formed of segments joined together to form the housing  302  with the terminals  330 ,  360  and the hold-down clips  390  disposed at least partially therein. In some embodiments, the power portion  304  may be comprised of a plurality of power segments  304 A,  304 B joined together, the signal portion  306  may be comprised of a plurality of signal segments  306 A joined together, and each of the end portions  308  may be comprised of an end segment  308 A. In some embodiments, the power segments  304 A,  304 B may alternate in the X direction and may be grouped as pairs  304 AB, as depicted in  FIG.  16 C . As shown in  FIG.  16 D , the terminals  330 ,  360 ,  390  generally extend in the Z direction parallel to the mating direction A. 
       FIG.  17 A  shows an elevational front view of the power segments  304 A,  304 B grouped as a pair  304 AB, according to some embodiments, and  FIG.  17 B  shows a perspective view of the pair  304 AB.  FIG.  17 C  shows a perspective view of the pair  304 AB in a partially disassembled state. The power segments  304 A,  304 B may be aligned in the X direction and may be arranged in an alternating pattern. In some embodiments, each of the power segments  304 A may be comprised of a conductive power terminal  330 A attached to an insulative housing portion  302 A. The power terminal  330 A may be comprised of a body portion  330   a , a contact portion  330   b , and a mounting portion  330   c . The mounting portion  330   c  may be comprised of one or more legs extending from the body portion  330   a  in the Z direction, which is parallel to the mating direction A, and the contact portion  330   b  may be comprised of fingers extending from the body portion  330   a  in the Z direction. The contact portion  330   b  may be disposed in an engagement space  310 A extending into the housing portion  302 A from the side surface  14  such that the contact portion  330   b  may contact a corresponding contact portion of a mating connector when the connector  300  and the mating connector are in a mated position. The mounting portion  330   c  may comprise part of the mounting portion  12  of  FIG.  2   . In some embodiments, each of the power segments  304 B may be comprised of a conductive power terminal  330 B attached to an insulative housing portion  302 B. The power terminal  330 B may be comprised of a body portion  330   a , a contact portion  330   b , and a mounting portion  330   c , similar to the power terminal  330 A. In some embodiments, the power segments  304 B may be the same as the power segments  304 A. In some other embodiments, the power segment  304 B may be a mirror image of the power segment  304 A. For example, as shown in the perspective view of  FIG.  17 D , the power terminals  330 A,  330 B may be comprised of respective curved sections  330   d  that are mirror images of each other. 
       FIG.  18 A  shows a plan top view of the signal segment  306 A, according to some embodiments, and  FIG.  18 B  shows a perspective top view of the signal segment  306 A.  FIG.  18 C  shows a perspective front view of the signal segment  306 A in a partially disassembled state. In some embodiments, the signal segment  306 A may be comprised of a plurality of conductive signal terminals  360 A attached to an insulative housing portion  302 C. Each of the signal terminals  360 A may be comprised of a contact pin that may be generally straight and aligned in the Z direction parallel to the mating direction. The signal terminals  360 A may be arranged in the housing portion  302 C such that they are aligned or stacked in a column in the Y direction. The contact portions of the signal terminals  360 A may be disposed in an engagement portion  310 B of the housing portion  302 C, which may be a recessed space that extends into the housing portion  302 C from the side surface  14  such that the contact portions of the signal terminals  330 A may contact corresponding contact portions of a mating connector. 
       FIG.  19 A  shows a plan top view of one of the end segments  308 A, according to some embodiments. As noted above, the end segments  308 A may be located on opposite ends of the connector  300  sandwiching the power segments  304 A,  304 B and the signal segments  306 A in between. As will be appreciated, the other one of the end segments  308 A may be a mirror image of the one shown in  FIG.  19 A  and therefore will not be described separately. In some embodiments, the end segment  308 A may be comprised of an insulative housing portion  302 D to which at least one of the hold-down clips  390  is attached.  FIG.  19 B  shows a perspective top view of an external side of the end segment  308 A, and  FIG.  19 C  shows a perspective top view of an internal side of the end segment  308 A. In some embodiments, a mounting portion  390   c  of the hold-down clip  390  may extend in the Z direction through a recess (not shown) of the housing portion  302 D. In some embodiments, the hold-down clip  390  may be a U-shaped retainer clip comprised of a plurality of legs ( 390   c ) extending from a bridge ( 390   a ). In some embodiments, the hold-down clip  390  may be attached to the housing portion  302 D such that the legs forming the mounting portion  390   c  extend from the housing portion  302 D in the Z direction. The end segment  308 A may have the same alignment structure as that described above for the end portion  308 . That is, in some embodiments, the alignment structure of the end segment  308 A may be comprised of the first and second portions  312   a ,  312   b  forming the multi-level recess  312 , which may extend from the side surface  14  into the housing  302 D. In some embodiments, a depth of the second portion  312   b  as measured from the side surface  14  may be greater than a depth of the first portion  312   a  from the side surface  14 . 
     According to some embodiments, the engagement spaces  310 A,  310 B,  310 C of the power segments  304 A,  304 B and the signal segments  306 A may be contiguous with each other to form the accommodation space  310  of the housing  300 , as shown in  FIGS.  15  and  16 A . In some embodiments, the accommodation space  310  may be comprised of the multilevel recesses  312  of the end segments  308 A such that the engagement spaces  310 A,  310 B,  310 C and the multilevel recesses  312  form a contiguous cavity in the housing  300 . 
     Stacked Receptacle Connector 
     In some miniature electronic systems there may be little space therein for wide electrical connectors. Therefore, it may be advantageous to be able to arrange the power terminals and the signal terminals in a densely or closely-packed configuration. According to some embodiments, a density of the power terminals in an electrical connector may be increased by arranging the power terminals in an array of rows and columns. That is, instead of a single row of power terminals aligned in the X direction, the connector may have at least two rows of power terminals stacked in the Y direction, such that each power terminal is part of a Y-direction column of at least one other power terminal. 
       FIG.  20 A  shows an elevational front view of a stacked receptacle connector  1000 , according to some embodiments, The connector  1000  may be a right-angle connector and may be similar in many ways to the connector  100  described above and therefore only stacking-related differences will be described. The connector  1000  may be comprised of an insulative housing  1102 , a plurality of conductive power terminals  1130  and a plurality of conductive signal terminals  1160 . The power terminals  1130  may be arranged in an array of rows and columns in a power portion  1104  of the connector  1000 , and the signal terminals  1160  may be arranged in an array of rows and columns in a signal portion  1106  of the connector  1000 . The signal portion  1104  may be similar to the signal portion  104  described above and therefore will not be described separately. 
       FIG.  20 B  shows an elevational front view of a section of the power portion  1104  comprised of four power terminals  1130 A,  1130 B arranged in two rows and two columns, according to some embodiments of the present invention. In some embodiments, the connector  1000  may have a segmented construction, similar to that of the connector  100  described above, with each power segment  1104 A comprised of a column or stack of two power terminals  1130 A,  1130 B. A height H 2  of the connector  1000  may be in a range from 9.0 mm to 13.0 mm (e.g., 10.0 mm to 12.0 mm). In some embodiments, a typical value for the height H 2  may be approximately 11.0 mm. 
     According to some embodiments, each of the power terminals  1130 A,  1130 B may be comprised of a power tab oriented horizontally such that its contact surface is aligned with the X direction. In some embodiments, the power terminals  1130 A,  1130 B may be the same. In some other embodiments, the power terminals  1130 A,  1130 B may have power tabs that are mirror images of each other, as depicted in  FIG.  20 B . With such an arrangement, a distance D 1  between center points of contact openings for the power terminals  1130 A,  1130 B in a column (i.e., in the Y direction) may be in a range from 1.5 mm to 4 mm (e.g., 1.5 mm to 2.5 mm). In some embodiments, a typical value for the distance D 1  may be approximately 2.0 mm. In some embodiments, a distance D 2  between center points of contact openings for the power terminals in adjacent columns and in the same row may be in a range from 6.0 mm to 8.0 mm (e.g., 6.5 mm to 7.5 mmm). In some embodiments, a typical value for the distance D 2  may be approximately 7.0 mm. In some embodiments, the distance D 2  also may be a width of the power segment  1104 A in the X direction. 
     For the purpose of comparison,  FIG.  21    shows an elevational front view of a section of the power portion  104  of the connector  100 , comprised of four consecutive power segments  104 A- 1 ,  104 B- 1 ,  104 A- 2 ,  104 B- 2  arranged in a single row, according to some embodiments. In some embodiments, the power segments  104 A- 1 ,  104 A- 2  may correspond to the power segment  104 A, and the power segments  104 B- 1 ,  104 B- 2  may correspond to the power segment  104 B. As described above in connection with  FIG.  7 A , the height H 1  of the connector  100  may be in a range from 5.0 mm to 14.0 mm. In some embodiments, a typical value for the height H 1  may be approximately 8.0 mm. As depicted in  FIG.  21   , the power terminals  130 A,  130 B may be oriented vertically, i.e., with their contact surfaces (e.g., power tabs) aligned with the Y direction. With such an arrangement, a distance D 3  between contact openings of adjacent power segments (e.g. the power segments  104 A- 1 ,  104 B- 1 ) may be in a range from 2.0 mm to 4.0 mm (e.g., 2.5 mm to 3.5 mmm). In some embodiments, a typical value for the distance D 3  may be approximately 3.0 mm. In some embodiments, a distance D 4  spanning from a center point of a contact opening of one power segment (e.g., the power segment  104 A- 1 ) and a center point of a contact opening of a fourth nearest power segment (e.g.,  104 A- 2 ) may be in a range from 8.0 mm to 10.0 mm. In some embodiments, a typical value for the distance D 4  may be approximately 9.0 mm. 
     According to some embodiments of the present invention, power terminals of a connector may be arranged relatively densely by stacking the power terminals in columns such that their power tabs are arranged horizontally in the columns. Such stacking may enable a separation distance of about 2 mm (corresponding to D 1 ). In contrast, without stacking, there may be a greater separation distance of about 3 mm (corresponding to D 3 ). 
     It should be understood that various alterations, modifications, and improvements may be made to the structures, configurations, and methods discussed above, and are intended to be within the spirit and scope of the invention disclosed herein. Further, although advantages of the present invention are indicated, it should be appreciated that not every embodiment of the invention will include every described advantage. Some embodiments may not implement any features described as advantageous herein. Accordingly, the foregoing description and attached drawings are by way of example only. 
     As one example, terminals are illustrated as having mounting legs for connection to a substrate such as a printed circuit board. In some embodiments, the legs may be suitable for through-hole soldering of the legs to holes in a circuit board. In other embodiments, the terminals may have tails for mounting to a circuit board, such as press-fit tails or surface-mount solder tails. 
     It should be understood that some aspects of the present technology may be embodied as one or more methods, and acts performed as part of a method of the present technology may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than shown and/or described, which may include performing some acts simultaneously, even though shown and/or described as sequential acts in various embodiments. 
     Various aspects disclosed herein may be used alone, in combination, or in a variety of arrangements not specifically discussed in the embodiments described in the foregoing and is therefore not limited in its application to the details and arrangement of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments. 
     Use of ordinal terms such as “first,” “second,” “third,” etc., in the description and the claims to modify an element does not by itself connote any priority, precedence, or order of one element over another, or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one element or act having a certain name from another element or act having a same name (but for use of the ordinal term) to distinguish the elements or acts. 
     All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms. 
     The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” 
     As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. 
     As used herein in the specification and in the claims, the phrase “equal” or “the same” in reference to two values (e.g., distances, widths, etc.) means that two values are the same within manufacturing tolerances. Thus, two values being equal, or the same, may mean that the two values are different from one another by ±5%. 
     The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and/or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. 
     As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of” or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e., “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law. 
     Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Use of terms such as “including,” “comprising,” “comprised of,” “having,” “containing,” and “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. 
     The terms “approximately” and “about” if used herein may be construed to mean within ±20% of a target value in some embodiments, within ±10% of a target value in some embodiments, within ±5% of a target value in some embodiments, and within ±2% of a target value in some embodiments. The terms “approximately” and “about” may equal the target value. 
     The term “substantially” if used herein may be construed to mean within 95% of a target value in some embodiments, within 98% of a target value in some embodiments, within 99% of a target value in some embodiments, and within 99.5% of a target value in some embodiments. In some embodiments, the term “substantially” may equal 100% of the target value.