Abstract:
An electrical connector assembly for electrically connecting to a chip module, includes a first metal casing having a first accommodating cavity, a first electrical connecting base received in the first accommodating cavity, a second metal casing having a second accommodating cavity, and a second electrical connecting base received in the second accommodating cavity. The second metal casing includes a fixing portion fixed to an outer surface of the first metal casing, and the second metal casing is fixed onto a circuit board. The first and second electrical connecting bases mate with first and second mating plugs. The first and second mating plugs are configured to transmit signals of different specifications. It is convenient to separate or combine the first electrical connecting base and the second connecting base.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 201520125120.4 filed in P.R. China on Mar. 4, 2015, the entire contents of which are hereby incorporated by reference. 
     Some references, if any, which may include patents, patent applications and various publications, may be cited and discussed in the description of this invention. The citation and/or discussion of such references, if any, is provided merely to clarify the description of the present invention and is not an admission that any such reference is “prior art” to the invention described herein. All references listed, cited and/or discussed in this specification are incorporated herein by reference in their entireties and to the same extent as if each reference was individually incorporated by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to an electrical connector assembly, and more particularly to an electrical connector assembly used for transmitting signals of different specifications. 
     BACKGROUND OF THE INVENTION 
     Chinese patent No. CN201220545966.X discloses a module connector. The module connector includes a data signal electrical connector, a first radio frequency signal electrical connector and a second radio frequency signal electrical connector which are separately and individually manufactured and molded, and a shielding casing made of a metal material. The shielding casing surrounds outer surfaces of the data signal electrical connector, the first radio frequency signal electrical connector and the second radio frequency signal electrical connector. The shielding casing includes an upper shielding casing and a lower shielding casing. The upper shielding casing and the lower shielding casing jointly cooperate to define multiple accommodating cavities accommodating the data signal electrical connector and the first and second radio frequency signal electrical connectors. 
     However, electrical connectors of different specifications are accommodated in the same shielding casing, thus it is not convenient to separate or combine the electrical connectors of the different specifications to be used individually or in combination. 
     Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies. 
     SUMMARY OF THE INVENTION 
     In one aspect, the present invention is directed to an electrical connector assembly that can be conveniently separated and assembled. 
     In one embodiment, an electrical connector assembly includes a first metal casing having a first accommodating cavity, a first electrical connecting base received in the first accommodating cavity, a second metal casing having a second accommodating cavity, and a second electrical connecting base received in the second accommodating cavity. The second metal casing has a fixing portion fixed to an outer surface of the first metal casing, and the second metal casing is fixed onto a circuit board. The first electrical connecting base is used for mating a first mating plug, and the second electrical connecting base is used for mating a second mating plug. The first mating plug and the second mating plug are configured to transmit signals of different specifications. 
     In one embodiment, the second accommodating cavity is located at a side of the first metal casing, the first metal casing wraps the periphery of the first electrical connecting base, and the second metal casing wraps the periphery of the second electrical connecting base. 
     In one embodiment, an extending portion extends from the fixing portion to define the second accommodating cavity, and the head and the tail of the extending portion are connected by means of laser soldering to form the second accommodating cavity. 
     In one embodiment, a stopping wall extends downward from the fixing portion to be stopped at the back of the first metal casing. 
     In one embodiment, the stopping wall is provided with a grounding portion extending downward and being soldered to the circuit board. 
     In one embodiment, the second metal casing is provided with a stopping portion stopped at the back of the second electrical connecting base. 
     In one embodiment, a top surface of the second metal casing is provided with an elastic sheet entering the second accommodating cavity downward and used for urging the second mating plug downward. 
     In one embodiment, the first electrical connecting base includes a first insulating body, multiple first terminals and multiple second terminals, an upper grounding sheet, a lower grounding sheet, and a middle shielding sheet. The first insulating body has a first base and a first tongue extending forward from the first base. The multiple first terminals and the multiple second terminals are respectively arranged into an upper row and a lower row and are embedded in the first insulating body. Each of the first terminals has a first contact portion exposed from an upper surface of the first tongue, and each of the second terminals has a second contact portion exposed from a lower surface of the first tongue. The upper grounding sheet is located above the first terminals. The lower grounding sheet is located below the second terminals and associated with the upper grounding sheet. The middle shielding sheet is located between the first terminals and the second terminals. 
     In one embodiment, the first mating plug includes a holding sheet contacting the middle shielding sheet, and the holding sheet is provided with an insertion portion extending downward and being inserted into the circuit board. 
     In one embodiment, the holding sheet is provided with a notch running through a lower edge of the holding sheet, and the holding sheet holds the first mating plug using the notch. 
     In one embodiment, the second electrical connecting base is of a specification for transmitting a radio frequency signal. 
     In one embodiment, the second metal casing wraps a top surface and two sides of the first metal casing, the fixing portion is fixed to the top surface of the first metal casing by means of laser soldering, and two buckling sheets extend downward respectively from two side edges of the fixing portion to buckle the two sides of the first metal casing. 
     In one embodiment, the first metal casing is provided with a rear wall stopped at the back of the first electrical connecting base, the first electrical connecting base is provided with a boss, and the rear wall is provided with a supporting leg extending downward and supported on the boss. 
     In one embodiment, the first mating plug has a third metal casing, the third metal casing has a fixing frame fixed to the circuit board and a mating frame extending forward from the fixing frame and entering the first accommodating cavity, an insulating sleeve is only sleeved over the mating frame, the insulating sleeve is provided with a limiting portion stopped at a front end of the mating frame, and the insulating sleeve is supported on the circuit board. 
     In one embodiment, the first mating plug includes an insulating block and a terminal group insert-molded in the insulating block, the terminal group has a soldering portion, the insulating block is provided with an isolation portion between two adjacent soldering portions, the insulating block is provided, at a side of the soldering portion, with a slot extending to the soldering portion, and a top surface of the slot is higher than a bottom surface of the isolation portion. 
     In one embodiment, the first mating plug includes a body, and an upper row of terminals and a lower row of terminals located in the body. Each of the upper row of terminals and the lower row of terminals has a conducting portion electrically connected to the first electrical connecting base. An upper shielding sheet is located above the body, and a lower shielding sheet is located below the body. The upper shielding sheet or the lower shielding sheet is provided with a main portion and a side portion bending and extending from each of two sides of the main portion. The main portion is provided with an opening corresponding to the conducting portion and passing through to the side portion. 
     Compared with the related art, certain embodiments of the present invention have the following beneficial advantages. 
     The first metal casing is provided with a first accommodating cavity accommodating the first electrical connecting base, the second metal casing is provided with a fixing portion fixed to the outer surface of the first metal casing, and the second metal casing is provided with a second accommodating cavity accommodating the second electrical connecting base, so that it is convenient to separate or combine the first electrical connecting base and the second connecting base. 
     These and other aspects of the present invention will become apparent from the following description of the preferred embodiment taken in conjunction with the following drawings, although variations and modifications therein may be effected without departing from the spirit and scope of the novel concepts of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate one or more embodiments of the invention and together with the written description, serve to explain the principles of the invention. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like elements of an embodiment. 
         FIG. 1  is a schematic three-dimensional exploded view of an electrical connector assembly according to one embodiment of the present invention. 
         FIG. 2  is a schematic three-dimensional exploded view of partial assembly of the electrical connector assembly according to one embodiment of the present invention. 
         FIG. 3  is another schematic three-dimensional exploded view of the electrical connector assembly according to one embodiment of the present invention. 
         FIG. 4  is a schematic assembly drawing of the electrical connector assembly according to one embodiment of the present invention. 
         FIG. 5  is a sectional view of  FIG. 4 . 
         FIG. 6  is a schematic three-dimensional exploded view of a mating connector according to one embodiment of the present invention. 
         FIG. 7  is a schematic three-dimensional exploded view of partial assembly of the mating connector according to one embodiment of the present invention. 
         FIG. 8  is another schematic three-dimensional exploded view of the mating connector according to one embodiment of the present invention. 
         FIG. 9  is a schematic third three-dimensional exploded view of the mating connector according to one embodiment of the present invention. 
         FIG. 10  is a schematic assembly drawing of the mating connector according to one embodiment of the present invention. 
         FIG. 11  is a sectional view of  FIG. 10 . 
         FIG. 12  is another sectional view of  FIG. 10 . 
         FIG. 13  is a schematic three-dimensional exploded view of a second embodiment of the mating connector according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is more particularly described in the following examples that are intended as illustrative only since numerous modifications and variations therein will be apparent to those skilled in the art. Various embodiments of the invention are now described in detail. Referring to the drawings, like numbers indicate like components throughout the views. As used in the description herein and throughout the claims that follow, the meaning of “a”, “an”, and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise. Moreover, titles or subtitles may be used in the specification for the convenience of a reader, which shall have no influence on the scope of the present invention. 
     It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Furthermore, relative terms, such as “lower” or “bottom” and “upper” or “top,” may be used herein to describe one element&#39;s relationship to another element as illustrated in the figures. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. For example, if the device in one of the figures is turned over, elements described as being on the “lower” side of other elements would then be oriented on “upper” sides of the other elements. The exemplary term “lower”, can therefore, encompasses both an orientation of “lower” and “upper,” depending of the particular orientation of the figure. Similarly, if the device in one of the figures is turned over, elements described as “below” or “beneath” other elements would then be oriented “above” the other elements. The exemplary terms “below” or “beneath” can, therefore, encompass both an orientation of above and below. 
     As used herein, “around”, “about” or “approximately” shall generally mean within 20 percent, preferably within 10 percent, and more preferably within 5 percent of a given value or range. Numerical quantities given herein are approximate, meaning that the term “around”, “about” or “approximately” can be inferred if not expressly stated. 
     As used herein, the terms “comprising”, “including”, “carrying”, “having”, “containing”, “involving”, and the like are to be understood to be open-ended, i.e., to mean including but not limited to. The description will be made as to the embodiments of the present invention in conjunction with the accompanying drawings in  FIGS. 1-13 . In accordance with the purposes of this invention, as embodied and broadly described herein, this invention, in one aspect, relates to an electrical connector. 
     As shown in  FIG. 1  to  FIG. 12 , a first embodiment of an electrical connector assembly of the present invention includes a first electrical connecting base  1 , a second electrical connecting base  2 , a first metal casing  3  and a second metal casing  4 . The first electrical connecting base  1  has a specification of transmitting a USB type C signal. The second electrical connecting base  2  has a specification of transmitting a radio frequency signal. The first metal casing  3  has a first accommodating cavity  300  for accommodating the first electrical connecting base  1 . The second metal casing  4  is fixed to an outer surface of the first metal casing  3 . The second metal casing  4  bends to form a second accommodating cavity  40  (in other embodiments, the second metal casing  4  is not merely limited to bending to form a second accommodating cavity  40 ) for accommodating the second electrical connecting base  2 . The second metal casing  4  is fixed to a circuit board. The electrical connector assembly and a mating connector are mated. The mating connector includes a first mating plug  5  mating the first electrical connecting base  1  and a second mating plug  8  mating the second electrical connecting base  2 . 
     As shown in  FIG. 1  to  FIG. 5 , the first electrical connecting base  1  includes a first insulating body  10 , multiple first terminals  11  and multiple second terminals  12 . The first insulating body  10  has a first base  101  and a first tongue  102  extending forward from the first base  101 . The rear side of the first base  101  is provided with two bosses  1011 . The top surface of the first base  101  is provided with a first protruding block  1012  protruding upward and two second protruding blocks  1013 . Two round posts  1014  are protruded downward from the bottom surface of the first base  101 , and are used for fixing the first electrical connecting base  1  onto the circuit board. The multiple first terminals  11  and the multiple second terminals  12  are arranged into an upper row and a lower row embedded in the first insulating body  10 . Each of the number of the first terminals  11  and the number of the second terminals  12  is twelve, and each of the first terminals  11  and the second terminals  12  includes two pairs of high-speed differential signal terminals. Each of the first terminals  11  has a first contact portion  111  exposed from the upper surface of the first tongue  102 , and each of the second terminals  12  has a second contact portion  121  exposed from the lower surface of the first tongue  102 . 
     As shown in  FIG. 1  to  FIG. 5 , a first middle shielding sheet  13  is inserted in the first insulating body  10 . The first middle shielding sheet  13  is located between the first terminals  11  and the second terminals  12 , to shield an interference signal between the first terminals  11  and the second terminals  12 . The first middle shielding sheet  13  has two first insertion portions  131  bending and extending downward. The first insertion portions  131  are soldered to the circuit board, and the first insertion portions  131  are located at the rear side of the first insulating body  10 . The first electrical connecting base  1  further includes an upper grounding sheet  14  and a lower grounding sheet  15  snap-fit with each other. The upper grounding sheet  14  is located above the first terminals  11 , and used for shielding an interference signal above the first terminals  11 . The upper grounding sheet  14  and the first metal casing  3  contact each other. The lower grounding sheet  15  is located below the second terminals  12 , and used for shielding an interference signal below the second terminals  12 . The lower grounding sheet  15  and the first metal casing  3  contact each other. 
     As shown in  FIG. 1  to  FIG. 5 , the second electrical connecting base  2  includes a second insulating body  20  and a third terminal  21  disposed in the second insulating body  20 . The second insulating body  20  includes a second base portion  201 . The second base portion  201  is in a shape of square. A semi-cylindrical mating portion  202  extends forward from the second base portion  201 , and the mating portion  202  extends forward and is roughly flush with the front surface of the first tongue  102 . The second insulating body  20  is provided with an insertion hole  203  running through the second insulating body  20 . The third terminal  21  is mounted in the insertion hole  203 . The third terminal  21  has a third contact portion  211  electrically contacting a second mating plug  8 . 
     As shown in  FIG. 1  to  FIG. 5 , the first metal casing  3  wraps the periphery of the first electrical connecting base  1 . The front end of the first metal casing  3  has a first mating opening  30  which is elliptic. The first mating opening  30  is used for insertion of a first mating plug  5  in dual orientations. The first metal casing  3  includes a first top wall  31 , a first bottom wall  32 , two first side walls  33  connecting the first top wall  31  and the first bottom wall  32 , and a rear wall  34  bending and extending downward from the back end of the first top wall  31  and used for stopping the first electrical connecting base  1 . Two ends of the rear wall  34  are provided with two supporting legs  341  extending downward (in other embodiments, the supporting leg  341  may be one or more in number) and supported on the bosses  1011 . The first top wall  31 , the first bottom wall  32 , and the two first side walls  33  define a peripherally closed space to accommodate the first electrical connecting base  1 . The first bottom wall  32  has a first seam  321 . The first top wall  31  is provided with a first engagement hole  311  for engaging with the first protruding block  1012 . Two engagement slots  312  are formed between the rear wall  34  and the first top wall  31 , and used for engaging with the two second protruding blocks  1013 . The first engagement hole  311  and the engagement slot  312  correspondingly are engaged with the first protruding block  1012  and the second protruding block  1013  and are used for fixing the first metal casing  3  and the first electrical connecting base  1 . Each of the first side walls  33  is provided with a first protruding portion  331  protruding outward (in other embodiments, the first protruding portions  331  may also be disposed at other positions of the first metal casing  3 , and the number of the first protruding portions  331  is not merely limited to two), and used for buckling the second metal casing  4 . 
     As shown in  FIG. 1  to  FIG. 5 , the second metal casing  4  wraps a top surface and two sides of the first metal casing  3 . The second metal casing  4  wraps the periphery of the second electrical connecting base  2 . The second metal casing  4  has a fixing portion  41 , and the fixing portion  41  is fixed to the first top wall  31  by means of laser soldering (the fixing portion is not merely limited to being soldered to the first top wall  31  by means of laser). A stopping wall  42  bends and extends downward from the back end of the fixing portion  41 , for stopping the first metal casing  3 . The stopping wall  42  includes two grounding portions  421  extending downward (in other embodiments, the number of the grounding portions  421  is not merely limited to two, and may be one or more) and soldered to the circuit board. Two first pins  43  bends and extends downward from a side of the fixing portion  41 . A first stopping portion  44  extends downward between the two first pins  43  and is used for stopping the first metal casing  3 . The first pin  43  is soldered to the circuit board. One such first stopping portion  44  also bends downward from another side of the fixing portion  41 . Moreover, the second metal casing  4  has two buckling sheets  45  corresponding to the first protruding portions  331 . The buckling sheets  45  extend downward from two sides of the fixing portion  41 . The first protruding portions  331  buckle the buckling sheets  45  and fixing the first metal casing  3  to the second metal casing  4 . The buckling sheets  45  are located behind the two first pins  43 . 
     As shown in  FIG. 1  to  FIG. 5 , an extending portion (not labeled) extends from another side of the fixing portion  41 . The extending portion includes a connection portion  406 . One of the second side walls  403  extends vertically and downward from an end of the connection portion  406 . The second bottom wall  402  extends horizontally from an end of the second side wall  403  in a direction away from the first metal casing  3 . The other of the second side walls  403  extends vertically and upward from an end of the second bottom wall  402 . The second top wall  401  extends horizontally from an end of the second side wall  403  in a direction toward the first metal casing  3 , and a part of the second top wall  401  and a part of the connection portion  406  are overlapped and used for laser soldering. The second top wall  401 , the second bottom wall  402 , and the two second side walls  403  connecting the second top wall  401  and the second bottom wall  402  define the second accommodating cavity  40  accommodating the second electrical connecting base  2 . The second accommodating cavity  40  and the first metal casing  3  are disposed abreast (in other embodiments, the second accommodating cavity  40  and the first metal casing  3  are not merely limited to being disposed abreast, and the second accommodating cavity  40  is not merely limited to one in number). The second top wall  401  is provided with an elastic sheet  4011  entering the second accommodating cavity  40  downward and used for urging a second mating plug  8  downward. A second stopping portion  405  bends downward from the back end of the second top wall  401  and is used for stopping the second electrical connecting base  2 . The back end of each of the second side walls  403  is provided with a second pin  404 , and the second pin  404  is soldered to the circuit board. 
     As shown in  FIG. 6  to  FIG. 12 , the first electrical connecting base  1  and a first mating plug  5  are mated. The first mating plug  5  has a first body  50 . A third metal casing  6  wraps the first body  50 . An upper insulating block  51 , a lower insulating block  52  and a fixing base  53  are accommodated in the first body  50 . An upper row terminal group  54  is embedded into the upper insulating block  51 , and a lower row terminal group  55  is embedded into the lower insulating block  52 . The upper row terminal group  54  and the lower row terminal group  55  are the same in structure. The upper row terminal group  54  and the lower row terminal group  55  have conducting portions  541  and conducting portions  551  respectively, which are used for contacting corresponding first contact portions  111  and second contact portions  121 . 
     As shown in  FIG. 6  to  FIG. 12 , the first body  50  includes a main body portion  501 , and a frame body  502  extending forward from the main body portion  501 . The height of the main body portion  501  in the vertical direction is greater than the height of the frame body  502 . Each of two sides of the main body portion  501  is provided with a second protruding portion  5011 , and the second protruding portions  5011  are used for fixing the first body  50  and the third metal casing  6 . The frame body  502  is provided with multiple terminal slots  5021  running through the upper wall and the lower wall of the frame body  502  and corresponding to the conducting portions  541  and  551  of the upper row terminal group  54  and the lower row terminal group  55 . The frame body  502  is further provided with several through-slots  5022  in front of the terminal slots  5021 . The front end of the frame body  502  is provided with a mating space  5023  used for accommodating the first electrical connecting base  1 . The mating space  5023  and the terminal slot  5021  are in communication with each other. A hollowing portion  5024  is depressed from each of two opposite sides of the frame body  502 . The upper insulating block  51  includes a flat plate portion  511  and a support base  512  protruding downward from the flat plate portion  511 . Two first grooves  5111  are depressed from the bottom surface of the flat plate portion  511 . Two first engagement blocks  521  protrude from the top surface of the lower insulating block  52 . The first engagement blocks  521  and the first grooves  5111  are engaged, so as to combine and fix the upper insulating block  51  and the lower insulating block  52 . A back end of each of two side edges of the flat plate portion  511  is provided with a second groove  5112 . Two second engagement blocks  531  protrude upward from the top surface of the fixing base  53 . The second engagement block  531  is accommodated in the second groove  5112 . Each inner side wall of the main body portion  501  is provided with a vertical holding slot  5012  corresponding to the second engagement block  531 . The fixing base  53  is inserted from the lower portion of the main body portion  501 , so that the second engagement blocks  531  are engaged with the holding slots  5012  to fix the fixing base  53  to the first body  50  (in other embodiments, the holding slots  5012  may also be disposed in a transverse direction, and the fixing base  53  is inserted from the back of the main body portion  501 , so that the second engagement blocks  531  are engaged with the holding slots  5012  to fix the fixing base  53  to the first body  50 ). Two third engagement blocks  522  protrude downward from the bottom surface of the lower insulating block  52 . The bottom surface of the frame body  502  is provided with two third grooves  5025 . The third engagement blocks  522  and the third grooves  5025  are engaged, so as to combine and fix the lower insulating block  52  and the first body  50 . 
     As shown in  FIG. 6  to  FIG. 12 , the first mating plug  5  further includes two holding sheets  56  (in other embodiments, the holding sheet  56  may be one or more in number) held in the first body  50 . Each of the holding sheets  56  includes a holding portion  561  fixed to the inner side of the main body portion  501 . A second insertion portion  562  bends and extends downward from an end of the holding portion  561 , and the second insertion portion  562  is soldered to the circuit board. The holding portion  561  is provided with a notch  5611 , and each of the notches  5611  is engaged with one of the second engagement blocks  531 , so as to fix the holding sheet  56  and the fixing base  53 . A plate portion  563  extends forward from the holding portion  561 , and the plate portion  563  is located at the hollowing portion  5024  of the frame body  502 . An end of the plate portion  563  is provided with an elastic portion  564 . The elastic portion  564  is a free end of the holding sheet  56 , and is movably located at the hollowing portion  5024 . The elastic portion  564  is located at the front end of the first body  50  to resist the first electrical connecting base  1 , and is used for providing a stable insertion and removing force, so as to ensure that the first mating plug  5  and the first electrical connecting base  1  are mated firmly, and are not easily disengaged. 
     As shown in  FIG. 6  to  FIG. 12 , the first mating plug  5  further includes a second middle shielding sheet  57 , which is located between the upper row terminal group  54  and the lower row terminal group  55 , and shields an interference signal between the upper row terminal group  54  and the lower row terminal group  55 . Two urging portions  571  each bend and extend outward and then backward from the front end at one side of the second middle shielding sheet  57  (in other embodiments, the urging portion  571  may be one or more) and urge the plate portion  563 . The urging portions  571  are elastic, and elastically urge the plate portion  563 . The second middle shielding sheet  57  are provided with two mounting holes  572  corresponding to the first engagement blocks  521  of the lower insulating block  52 . Each of the first engagement blocks  521  passes through the corresponding mounting hole  572  to engage with the first groove  5111  of the upper insulating block  51 , and the second middle shielding sheet  57  is fixed between the upper insulating blocks  51  and the lower insulating blocks  52 . Therefore the middle shielding sheet  57  is fixed simply, mounted easily, and fixed without the need of adding another fixing structure, and is simple in structure. 
     As shown in  FIG. 6  to  FIG. 12 , the first mating plug  5  further includes an upper shielding sheet  58  and a lower shielding sheet  59 . The upper shielding sheet  58  is fixed to the top surface of the frame body  502 , and the lower shielding sheet  59  is fixed to the bottom surface of the frame body  502 . Both the upper shielding sheet  58  and the lower shielding sheet  59  are located in the third metal casing  6 , and contact the third metal casing  6 . The upper shielding sheet  58  is located above the upper row terminal group  54 , and used for shielding an interference signal above the upper row terminal group  54 . The lower shielding sheet  59  is located below the lower row terminal group  55 , and used for shielding an interference signal below the lower row terminal group  55 . The upper shielding sheet  58  and the lower shielding sheet  59  are respectively provided with an opening  584  and an opening  594  corresponding to the terminal slot  5021 . Five first elastic arms  581  and five first elastic arms  591  contacting the third metal casing  6  protrude backward from the back end of the upper shielding sheet  58  and the back end of the lower shielding sheet  59  respectively (in other embodiments, the first elastic arms  581  and  591  may be one or more in number) and are grounded. Three bending portions  582  and three bending portions  592  respectively bend from the front end of the upper shielding sheet  58  and the front end of the lower shielding sheet  59  toward the mating space  5023 , and the bending portions  582  and  592  pass through the through-slots  5022  to contact the first electrical connecting base  1 . A second elastic arm  583  or  593  is disposed between the bending portions  582  or  592  to contact the third metal casing  6  and is grounded. 
     As shown in  FIG. 6  to  FIG. 12 , the third metal casing  6  includes a fixing frame  65  and a mating frame  66  extending forward from the fixing frame  65  and entering the first accommodating cavity  300 . The mating frame  66  wraps the outer surface of the frame body  502 , and the fixing frame  65  wraps a top surface and two side surfaces of the main body portion  501 . The front end of the mating frame  66  has a second mating opening  61  which is elliptic, and the second mating opening  61  is used for insertion of the first electrical connecting base  1 . The fixing frame  65  is provided with a second engagement hole  62  corresponding to each of the second protruding portions  5011 . The second protruding portion  5011  is engaged with the corresponding second engagement hole  62 , so as to fix the third metal casing  6  and the first body  50 . Two third pins  63  extend downward from each of two sides of the fixing frame  65 . The third pins  63  are soldered to the circuit board. A third stopping portion  64  bends downward from the back end of the top surface of the fixing frame  65  to stop the first mating plug  5 . 
     As shown in  FIG. 6  to  FIG. 12 , an insulating sleeve  7  is only sleeved over the mating frame  66  but not sleeved over the fixing frame  65 . The insulating sleeve  7  is made of insulating plastic. Two protruding columns  71  supported on the circuit board protrude downward from the bottom surface of the insulating sleeve  7  (in other embodiments, the insulating sleeve  7  may also be supported on the circuit board in other manners, the protruding columns  71  are not merely limited to protruding downward, and the protruding columns  71  are not merely limited to two in number), and used for supporting the mating portion  202  during soldering, so that the first mating plug  5  keeps balanced. The insulating sleeve  7  has a wrapping portion  72  wrapping the peripheral wall of the mating frame  66 . A limiting portion  73  extends vertically from the front end of the wrapping portion  72 , and the limiting portion  73  is stopped at the front end of the mating frame  66 . The top surface of the wrapping portion  72  is provided with a sheet  74 , and the sheet  74  is in interference fit with the mating frame  66  and used for clamping the third metal casing  6 . 
     As shown in  FIG. 6  to  FIG. 12 , the second electrical connecting base  2  and a second mating plug  8  are mated. The second mating plug  8  includes a second body  81  and a cylindrical terminal  82  disposed in the second body  81 . The second body  81  is cylindrical. 
     Referring to  FIG. 13 , a second embodiment of an electrical connector assembly of the present invention is shown, and is different from the first embodiment as follows: 
     1. The bottom surface of the support base  512  of the upper insulating block  51  is provided with a slot  5122  at a side of the soldering portion  542 . The upper insulating block  52  is provided with an isolation portion  5121  between adjacent two soldering portions  542 . The top surface A of the slot  5122  is higher than the bottom surface of the isolation portion  5121 , and the slot  5122  may prevent deckle edges and barbs generated at positions at which the upper row terminal group  54  contacts the bottom of the support base  512  from being higher than the soldering portion  542 , which affects soldering of the upper row terminal group  54  to the circuit board. 
     2. The upper shielding sheet  58  and the lower shielding sheet  59  include respectively a main portion  585  and a main portion  595  and a side portion  586  and a side portion  596  bending and extending from each of two sides of the main portion  585  and the main portion  595 . The main portion  585  and the main portion  595  are respectively provided with openings  584  and  594  passing through to the side portions  586  and  596 . When the first mating plug  5  and the first electrical connecting base  1  are mated, the conducting portions  541  and  551  of the upper row terminal group  54  and the lower row terminal group  55  pass through the terminal slot  5021  to contact the upper shielding sheet  58  or the lower shielding sheet  59  may be avoided. 
     In summary, the electrical connector assembly according to certain embodiments of the present invention, among other things, has the following beneficial advantages: 
     (1) The first metal casing  3  is provided with a first accommodating cavity  300  accommodating the first electrical connecting base  1 , the second metal casing  4  is provided with a fixing portion  41  fixed to the outer surface of the first metal casing  3 , and the second metal casing  4  is provided with a second accommodating cavity  40  accommodating the second electrical connecting base  2 , so that it is convenient to separate or combine the first electrical connecting base  1  and the second connecting base  2 . 
     (2) The first metal casing  3  wraps the periphery of the first electrical connecting base  1 , and the second metal casing  4  wraps the periphery of the second electrical connecting base  2 , so that mutual shielding between the first electrical connecting base  1  and the second electrical connecting base  2  is better. 
     (3) The top surface of the second metal casing  4  is provided with an elastic sheet  4011  entering the second accommodating cavity  40  downward and used for urging the second mating plug  8  downward, so as to increase stability of cooperation between the second electrical connecting base  2  and the second mating plug  8 . 
     (4) The first electrical connecting base  1  is of a specification of transmitting a USB type C signal, and the second electrical connecting base  2  is of a specification of transmitting a radio frequency signal, so as to implement combined use of the USB type C electrical connector and the radio frequency signal electrical connector. 
     (5) The insulating sleeve  7  is only sleeved over the mating frame  66 , and the insulating sleeve  7  is supported on the circuit board, so that the first mating plug  5  keeps balanced when being soldered to the circuit board. 
     (6) The bottom surface of the support base  512  of the upper insulating block  51  is provided with a slot  5122  at a side of a soldering portion  542  of the upper row terminal group  54 , and the upper insulating block  52  is provided with an isolation portion  5121  between adjacent soldering portions  542 . The top surface A of the slot  5122  is higher than the bottom surface of the isolation portion  5121 . The slot  5122  may prevent deckle edges and barbs generated at positions at which the upper row terminal group  54  contacts the bottom of the support base  512  from being higher than the soldering surface of the upper row terminal group  54 , which affects the soldering of the upper row terminal group  54  to the circuit board. 
     (7) The upper shielding sheet  58  and the lower shielding sheet  59  are respectively provided with a main portion  585  and a main portion  595 , and a side portion  586  and a side portion  596  bending and extending from each of two sides of the main portion  585  and the main portion  595 . The main portion  585  and the main portion  595  are respectively provided with openings  584  and  594  passing through to the side portions  586  and  596 . When the first mating plug  5  and the first electrical connecting base  1  are mated, the conducting portions  541  and  551  of the upper row terminal group  54  and the lower row terminal group  55  pass through the terminal slot  5021  to contact the upper shielding sheet  58  or the lower shielding sheet  59  may be avoided. 
     The foregoing description of the exemplary embodiments of the invention has been presented only for the purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching. 
     The embodiments are chosen and described in order to explain the principles of the invention and their practical application so as to activate others skilled in the art to utilize the invention and various embodiments and with various modifications as are suited to the particular use contemplated. Alternative embodiments will become apparent to those skilled in the art to which the present invention pertains without departing from its spirit and scope. Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing description and the exemplary embodiments described therein.