Patent Publication Number: US-2015079853-A1

Title: Electrical connector

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an electrical connector, and more particularly to a board-to-board electrical connector and an integrally injection molded electrical connector having elastically movable terminals embedded into a plastic base. 
     2. Related Art 
     Referring to  FIGS. 1 and 2 , a conventional board-to-board electrical connector includes a female base  10 , female terminals  17 , a male base  23  and male terminals  28 . 
     The female base  10  has a middle portion  11  and a peripheral portion  12 . The middle portion  11  and the peripheral portion  12  form two concave portions  13 . The peripheral portion  12  has one row of vertical female terminal fixing slots  14 , and one row of female terminal moving slots  15  are disposed on each of two sides of the middle portion  11 . 
     The female terminals  17  is mounted on the female base  10  and is formed by pressing a metal sheet to have: a force arm  18 , which is elastically movable in the female terminal moving slot  15  and has a contact point  19  projecting beyond the female terminal moving slot  15 ; a fixing portion  21 , which extends from bottom to top and is inserted and fixed into the female terminal fixing slot  14 ; and a pin portion  20  horizontally extending out of the female base  10 . 
     The middle of the male base  23  is formed with a concave portion  24 . Each of two sides of the male base  23  is formed with one row of vertical male terminal slots  25 . Two sides of the male base  23  are fit with two concave portions  13  of the female base  10 , and the middle portion  11  of the female base is fit with the concave portion  24  at the middle of the male base. 
     The male terminals  28  is mounted in the male terminal slot  25  of the male base  23  and is formed by bending a metal sheet to have: a fixing portion  29  fixed to the male terminal slot  25 ; a contact sheet  30  connected to one end of the fixing portion  29  and stacked on the fixing portion  29 , wherein the contact sheet  30  is formed with a convex portion  32 ; and a pin portion  31  connected to the other end of the fixing portion  29  and horizontally extending out of the male base  23 . 
     As shown in  FIG. 2 , after the male base  23  is combined with the female base  10 , the contact point  19  of the female terminal  17  is engaged and locked with the top of the convex portion  32  of the male terminal  28  to prevent the male base  23  and the female base  10  from being separated in a vertical direction. Thus, the pin portion  31  of the male terminal is connected to a first circuit board  33 , and the pin portion  20  of the female terminal is connected to the second circuit board  34  so that the first circuit board  33  and the second circuit board  34  are electrically connected together. 
     The conventional electrical connectors still have the following drawbacks. 
     First, the fixing portions  29  and  21  of the male and female terminals are fixed to the male and female bases  23  and  10  in the vertical direction so that the requirement of the low-height electrical connector cannot be satisfied. 
     Second, the vertical engaging and locking between the male base  23  and the female base  10  are made through the male and female terminals, so the male and female terminals as well as the male and female bases are required to have the high manufacturing and assembling precision. 
     SUMMARY OF THE INVENTION 
     A main object of the invention is to provide an electrical connector, in which the contacts of the male and female terminals are plate surfaces and cut surfaces vertically elastically rest against each other to achieve the excellent contact effect and ensure the electrical connection. In addition, the requirement of the assembling precision of the male and female terminals is low and can be easily manufactured. 
     Another main object of the invention is to provide an electrical connector having male and female terminals formed by bending the plate surface, and fixing portions transversally and horizontally fixed with the male and female bases, so that the low-height requirement of the male and female bases can be satisfied. 
     Still another main object of the invention is to provide an electrical connector, in which the engaging structure facilitates the direct engagement between the male and female bases, and the male and female terminals only provide the conducting function without mutual engaging, so that the male and female terminals are simpler and can be easily manufactured and assembled. 
     Yet still another main object of the invention is to provide an electrical connector an electrical connector, in which the base can be embedded into and integrally injection molded with the elastically movable terminal, and the extension of the elastically movable terminal is combined with the base to achieve the strengthening effect. 
     To achieve the above-identified objects, the invention provides an electrical connector, comprising: a female base, which is an insulation material and has a middle formed with a depressed fitting slot; female terminals arranged on at least one side of the female base, wherein the female terminal is made of a metal sheet and integrally formed with an extension, a fixing portion and a pin, the fixing portion is fixed to the female base, the extension has a contact disposed in the fitting slot, and the pin extends out of the female base; a male base, which is made of an insulation material and mounted in the fitting slot of the female base; and male terminals arranged on at least one side of the male base, wherein the male terminal is made of a metal sheet and integrally formed with an extension, a fixing portion and a pin, the fixing portion is fixed to the male base, the extension has a contact elastically resting against the contact of the female terminal, and the pin extends out of the male base. Elastic resting between a plate surface and a cut surface is present between the contacts of the male and female terminals, one of the contacts of the male and female terminals is the plate surface, the other of the contacts of the male and female terminals is the cut surface, one end of the extension of one of the male and female terminals is connected to one end of the fixing portion of the terminal, the other end of the terminal extends to the fitting slot of the female base, and the extension is elastically and vertically movable, and has an end section formed with the contact, which is vertically projecting. 
     The invention further provides an electrical connector, comprising: a female base, which is made of an insulation material and has a middle formed with a fitting slot; female terminals arranged on at least one side of the female base, wherein the female terminal is made of a metal sheet and integrally formed with an extension, a fixing portion, and a pin, the fixing portion is fixed to the female base, the extension has a contact disposed in the fitting slot, and the pin extends out of the female base; a male base is made of an insulation material and mounted in the fitting slot of the female base; and male terminals arranged on at least one side of the male base, wherein the male terminal is made of a metal sheet and integrally formed with an extension, a fixing portion and a pin, the fixing portion is fixed to the male base, the extension has a contact elastically resting against the contact of the female terminal, and the pin extends out of the male base. At least one of the male and female terminals is formed by bending a plate surface and has the fixing portion transversally fixed. 
     The invention further provides an electrical connector, comprising: a female base, which is made of an insulation material and has a middle formed with a fitting slot; female terminals arranged on at least one side of the female base, wherein the female terminal is made of a metal sheet and integrally formed with an extension, a fixing portion and a pin, the fixing portion is fixed to the female base, the extension has a contact disposed in the fitting slot, and the pin extends out of the female base; a male base, which is made of an insulation material and mounted in the fitting slot of the female base; male terminals arranged on at least one side of the male base, wherein the male terminal is made of a metal sheet and integrally formed with an extension, a fixing portion and a pin, the fixing portion is fixed to the male base, the extension has a contact elastically resting against the contact of the female terminal, and the pin extends out of the male base; and an engaging structure, which makes the male base be combined with and engaged with the female base so that the contact of the male terminal elastically rests against the contact of the female terminal. The engaging structure has a first engaging portion on two sides of the male base, and is integrally formed with a second engaging portion on two sides of the fitting slot of the female base, the first and second engaging portions are a transversal projection and a concave portion engaging with each other, the contact of the male terminal is disposed on an inner side of the first engaging portion, and the contact of the female terminal is disposed on an inner side of the second engaging portion. 
     The invention further provides an electrical connector, comprising: a base, which is made of an insulation material and has a fitting slot; and terminals arranged on the base, wherein the terminal is formed by bending a metal sheet and is integrally formed with an extension, a fixing portion and a pin, wherein the fixing portion is fixed to the base, the extension is connected to one end of the fixing portion and has a projecting contact disposed in the fitting slot, and the pin is connected to the other end of the fixing portion and extends out of the base. The fixing portions of at least one row of terminals are embedded into the base and are integrally injection molded, the extensions of the one row of terminals have first portions and second portions, the first portions extend transversally, one end of the first portion is connected to one end of the fixing portion, the other end of the first portion is embedded into the base and fixed, the second portion extends to the fitting slot and vertically corresponds to the first portion, the second portion is elastically movable and has the contact, and the base has an empty region above the first portion vertically corresponding to an elastically movable portion of the second portion. 
     The invention has the following characteristics and advantages. 
     First, the contacts of the male and female terminals vertically elastically rest against each other and are a plate surface and a cut surface elastic resting against each other. So, the excellent contact effect is obtained to ensure the electrical connection. In addition, the requirement of the assembling precision of the male and female terminals is low and the product can be easily manufactured. 
     Second, the male and female terminals are formed by bending the plate surface and have fixing portions transversally and horizontally fixed with the male and female bases. Thus, the low-height requirement on the male and female bases can be satisfied. 
     Third, the engaging structure facilitates the direct engagement between the male and female bases, and the male and female terminals only provide the conducting function without mutual engaging, so that the male and female terminals are simpler and can be easily manufactured and assembled. 
     Fourth, the base can be embedded into and integrally injection molded with the elastically movable terminals, and the extensions of the elastically movable terminals are combined with the base to achieve the strengthening effect. 
     Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention. 
         FIG. 1  is a decomposed schematic cross-sectional view showing a conventional electrical connector. 
         FIG. 2  is a schematically cross-sectional view showing a used state of a conventional electrical connector. 
         FIG. 3  is an exploded cross-sectional side view showing male and female connectors according to the first embodiment of the invention. 
         FIG. 4  is an assembled cross-sectional side view showing the male and female connectors according to the first embodiment of the invention. 
         FIG. 5  is a pictorially exploded view showing the male and female connectors according to the first embodiment of the invention. 
         FIG. 6  is an exploded cross-sectional side view showing male and female connectors according to the second embodiment of the invention. 
         FIG. 7  is an assembled cross-sectional side view showing the male and female connectors according to the second embodiment of the invention. 
         FIG. 8  is an exploded cross-sectional side view showing male and female connectors according to the third embodiment of the invention. 
         FIG. 9  is an assembled cross-sectional side view showing the male and female connectors according to the third embodiment of the invention. 
         FIG. 10  is an exploded cross-sectional side view showing male and female connectors according to the fourth embodiment of the invention. 
         FIG. 11  is an assembled cross-sectional side view showing the male and female connectors according to the fourth embodiment of the invention. 
         FIG. 12  is an exploded cross-sectional side view showing male and female connectors according to the fifth embodiment of the invention. 
         FIG. 13  is an assembled cross-sectional side view showing the male and female connectors according to the fifth embodiment of the invention. 
         FIG. 14  is a pictorially exploded view showing male and female connectors according to the sixth embodiment of the invention. 
         FIG. 15  is an exploded cross-sectional side view showing the male and female connectors according to the sixth embodiment of the invention. 
         FIG. 16  is an assembled cross-sectional side view showing the male and female connectors according to the sixth embodiment of the invention. 
         FIG. 17  is a pictorial view showing the female terminal according to the sixth embodiment of the invention. 
         FIG. 18  is a pictorially exploded view showing the male and female connectors according to the seventh embodiment of the invention. 
         FIG. 19  is an exploded cross-sectional side view showing male and female connectors according to the seventh embodiment of the invention. 
         FIG. 20  is an assembled cross-sectional side view showing the male and female connectors according to the seventh embodiment of the invention. 
         FIG. 21  is a pictorial view showing the female terminal according to the seventh embodiment of the invention. 
         FIG. 22  is a pictorially exploded view showing the male and female connectors according to the eighth embodiment of the invention. 
         FIG. 23  is an exploded cross-sectional side view showing the male and female connectors according to the eighth embodiment of the invention. 
         FIG. 24  is an assembled cross-sectional side view showing the male and female connectors according to the eighth embodiment of the invention. 
         FIG. 25  is a pictorial view showing the female terminal according to the eighth embodiment of the invention. 
         FIG. 26  is a pictorial view showing the male terminal according to the eighth embodiment of the invention. 
         FIG. 27  is a pictorial view showing the male connector according to the eighth embodiment of the invention. 
         FIG. 28  is a pictorial view showing the female connector according to the eighth embodiment of the invention. 
         FIG. 29  is an exploded cross-sectional side view showing the male and female connectors according to the ninth embodiment of the invention. 
         FIG. 30  is an assembled cross-sectional side view showing the male and female connectors according to the ninth embodiment of the invention. 
         FIG. 31  is an assembled cross-sectional side view showing the female connector of the ninth embodiment of the invention connected to the conventional male connector. 
         FIG. 32  is an assembled cross-sectional side view showing the male connector of the ninth embodiment of the invention connected to the conventional female connector. 
         FIG. 33  is an exploded cross-sectional side view showing the male and female connectors according to the tenth embodiment of the invention. 
         FIG. 34  is an exploded cross-sectional side view showing the male and female connectors according to the eleventh embodiment of the invention. 
         FIG. 35  is an exploded cross-sectional side view showing the male and female connectors according to the twelfth embodiment of the invention. 
         FIG. 36  is a pictorial view showing the female terminal according to the twelfth embodiment of the invention. 
         FIG. 37  is an exploded cross-sectional side view showing the male and female connectors according to the 13th embodiment of the invention. 
         FIG. 38  is a pictorial view showing the male connector according to the 14th embodiment of the invention. 
         FIG. 39  is a cross-sectional side view showing the female connector according to the 15th embodiment of the invention. 
         FIG. 40  is a pictorially exploded view showing the 16th embodiment of the invention. 
         FIG. 41  is a pictorially assembled view showing the 16th embodiment of the invention. 
         FIG. 42  is a pictorial view showing the upper metal cover according to the 16th embodiment of the invention. 
         FIG. 43  is a cross-sectional side view (the position of the terminal  100 ′) according to the 16th embodiment of the invention. 
         FIG. 44  is a cross-sectional side view (the position of the terminal  100 ) showing the used state according to the 16th embodiment of the invention. 
         FIG. 45  is a cross-sectional side view showing the used state according to the 16th embodiment of the invention. 
         FIG. 46  is a pictorially exploded view according to the 17th embodiment of the invention. 
         FIG. 47  is a pictorial cross-sectional view according to the 17th embodiment of the invention. 
         FIG. 48  is a cross-sectional side view (the position of the terminal  100 ′) according to the 17th embodiment of the invention. 
         FIG. 49  is a cross-sectional side view (the position of the sliding slot  95 ) according to the 17th embodiment of the invention. 
         FIG. 50  is a cross-sectional side view showing a used state according to the 17th embodiment of the invention. 
         FIG. 51  is an exploded cross-sectional side view showing the male and female connectors according to the 18th embodiment of the invention. 
         FIG. 52  is a pictorially exploded view according to the 19th embodiment of the invention. 
         FIG. 53  is a cross-sectional side view (the position of the terminal  100 ′) according to the 19th embodiment of the invention. 
         FIG. 54  is a cross-sectional side view (the position of the terminal  100 ) according to the 20th embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements. 
     Referring to  FIGS. 3 to 5 , the first embodiment of the invention is a board-to-board electrical connector including a female base  40 , female terminals  50 , a male base  70 , male terminals  80 , four female lugs  80 , four male lugs  85  and an engaging device. 
     The female base  40  is an insulating plastic material and has a middle formed with a depressed fitting slot  41 , which is a single slot. One row of female terminal slots  42  are disposed on each of two sides of the fitting slot  41 . The female terminal slot  42  has a transversal and horizontal fixing slot  421 . A transversal fitting concave portion  45  is present above the fixing slot  421 . The concave portion  45  has a top engaging surface  44 . Each of two outer ends of one row of female terminal slots  42  on one side of the female base  40  is formed with a vertically extending groove  49 . The outer end of the groove  49  is formed with a female lug slot  48 . The female lug slot  48  has a transversally and horizontally extending fixing slot  481 . 
     The female terminals  50  in two rows are separately arranged in two rows of female terminal slots  42  on two sides of the female base  40  to form a female connector. The female terminal  50  is formed by bending the plate surface of the metal sheet and is integrally formed with an extension  51 , a fixing portion  52  and a pin  53 . The fixing portion  52  transversally and horizontally extends. A projecting barb is formed on each of two sides of the fixing portion  52  and is horizontally fixed to the fixing slot  421  of the female terminal slot  42 . One end of the extension  51  is connected to one end of the fixing portion  52  and is inclined and extends upwards so that the distal end extends to the fitting slot  41  of the female base  40 . The extension  51  is an inclined force arm, is elastically and vertically movable and has a distal-end cut surface, which is most convex upward contact  54 . The contact  54  is a natural arc or a deburred chamfer formed upon pressing. The pin  53  is connected to the other end of the fixing portion  52  and has a horizontal end section, wherein the pins  53  of the two rows of female terminals extend out of two sides of the female base  40 , respectively. 
     The male base  60  is made of an insulating plastic material and is in the form of a single convex portion mounted in the fitting slot  41  of the female base  40 . Each of two sides of the male base  60  is formed with one row of male terminal slots  62 . The male terminal slot  62  has a transversally and horizontally extending fixing slot  621 . Each of two outer ends of the one row of male terminal slots  62  has a male lug slot  68 , which has a transversally and horizontally extending fixing slot  681 . 
     The male terminals  70  in two rows are separately arranged in two rows of male terminal slots  62  of the male base  60  to form a male connector. The male terminal  70  is formed by bending the plate surface of the metal sheet, and is integrally formed with an extension  71 , a fixing portion  72  and a pin  73 . The extension  71  has a transversally and horizontally extending horizontal section. Two sides of the horizontal section have the fixing portion  72 . The fixing portion  72  is a projecting barb. The bottom plate surface of the horizontal section is the contact  74 . The fixing portion  72  and the fixing slot  621  of the male terminal slot are horizontally fixed, so the extension  71  is not elastically movable. The contact  74  elastically rests against the contact  54  of the female terminal  50 . The pin  73  is connected to the extension  71  and has a horizontal end section, wherein the pins  73  of the two rows of male terminals extend out of two sides of the male base  60 , respectively. 
     The contacts  74  and  54  of the male and female terminals are the only mutual contacting and conducting portions of the male and female terminals. 
     The female lug  80  has a fixing portion  82  and a pin  83 . The fixing portion  82  transversally and horizontally extends. The fixing portion  82  and the fixing slot  481  of the female lug slot  48  are horizontally fixed. The pin  83  is connected to one end of the fixing portion  82  and has an end section horizontally extending out of the female base  40 . The structure of the female lug  80  is completely the same as the fixing portion  52  and the pin  53  of the female terminal  50 . 
     The male lug  85  has a fixing portion  87  and a pin  88 . The fixing portion  87  transversally and horizontally extends. The fixing portion  87  and the fixing slot  681  of the male lug slot  68  are horizontally fixed, and the pin  88  is connected to one end of the fixing portion  87  and has an end section horizontally extending out of the male base  60 . 
     The engaging structure makes the male base  60  engage with the female base  40  so that the contact  74  of the male terminal  70  elastically rests against the contact  54  of the female terminal  50 . The engaging structure is integrally formed with first engaging portions on two sides of the bottom end of the male base  40 , and integrally formed with second engaging portions on two sides of the fitting slot  41  of the female base  40 . The first and second engaging portions are transversal projections engaging with the concave portions. The first engaging portions are transversal projecting projections  64 . The projections  64  vertically correspond to the one row of male terminals  70 . The top and bottom ends of the projection  64  are formed with bevel guides. The second engaging portions are the transversal fitting concave portions  45 . The concave portion  45  is formed in the female terminal slot, and is in the transversally penetrating through state. 
     As shown in  FIG. 4 , when the male base  60  is combined with the female base  40 , the contact  74  of the male terminal  70  elastically rests against the contact  54  of the female terminal  50 . The projections  64  of the male base  60  are engaged with the concave portions  45  of the female base  40  to prevent the male and female bases  60  and  40  from separating from each other. As shown in  FIG. 5 , the female base  40  has grooves  49 , which make two side portions of the fitting slot  41  be easily elastically movable to facilitate the projections  64  of the male base  60  in engaging into the concave portions  45  of the female base  40 . 
     The pins  73  of the male terminals  70  are electrically connected to the bonding pads  331  of the first circuit board  33 , and the pins  53  of the female terminals  50  are electrically connected to the bonding pads  341  of the second circuit boards  34 , so that the first circuit board  33  is electrically connected to the second circuit board  34 . 
     Upon manufacturing, one row of female terminals  50  and two female lugs  80  are formed by pressing the same metal sheet, and one row of male terminals  70  and two male lugs  85  are formed by pressing the same metal sheet. So, as shown in  FIG. 5 , the platingless layer sections  81  of the distal ends of the pins of the two female lugs  80  and the platingless layer sections  56  of the distal ends of the pins of one row of female terminals  50  on the same side have the same height, and the platingless layer sections  86  of the distal ends of the pins of the two male lugs  85  and the platingless layer sections  76  of distal ends of the pins of the one row of male terminals  70  on the same side have the same height. 
     According to the above-mentioned descriptions, the embodiment can be concluded as having the following features and advantages. 
     First, the contacts of the male and female terminals vertically elastic rest against each other, and the elastic resting is present between the plate surface and the cut surface. So, the excellent contact effect is obtained to ensure the electrical connection. 
     Second, the male and female terminals  70  and  40  are formed by bending the plate surface and the fixing portions  72  and  42  thereof are transversally and horizontally fixed to the male and female bases  60  and  40 . Thus, the low-height requirement of the male and female bases  60  and  40  can be satisfied. 
     Third, the male and female bases can be easily and directly engaged with each other, and the male and female terminals only have the conducting function without mutual engaging so that the male and female terminals become simpler and can be easily manufactured and assembled. 
     As shown in  FIGS. 6 and 7 , the second embodiment of the invention is substantially the same as the first embodiment except that the middle of the female base  40  of this embodiment has a projecting middle portion  46  so that the fitting slot  41  includes two concave portions on two sides of the middle portion. The female terminal slot  42  extends to the middle portion  46 . The middle of the male base  60  has a concave portion  61  so that two sides are formed with convex portions  69 . The concave portion  61  of the male base corresponds to the middle portion  46  of the female base  40 . The convex portion  69  on two sides of the male base is correspondingly fit with the fitting slot  41  of the two concave portions of the female base. The extension of the female terminal  51  has a horizontal force arm  511  and a laterally and elastically movable force arm  512 . The horizontal force arm  511  has one end connected to the fixing portion  52 , and the other end extending to the middle portion  46  of the female base  40 . The laterally and elastically movable force arm  512  is connected to the horizontal force arm  511  and extends vertically upwards. The plate surface of the distal section of the laterally and elastically movable force arm  512  is bent reversely downwards and slantingly projects toward the fitting slot  41 . The cut surface of the distal end of the extension  51  is the contact  54 . 
     The male terminal slot  62  of the male base has a vertically extending fixing slot  621 . The extension  71  of the male terminal  70  is substantially formed by bending the plate surface into the U shape. The vertical front section of the inner side of the extension  71  is the contact  74 , and the tail section is the fixing portion  72 . The contact  74  laterally communicates with the concave portion  61 . The male terminal  70  is assembled from bottom to top, and the fixing portion  72  thereof is fixed to the vertical fixing slot  621 . 
     In addition, the extension  71  of the male terminal  70  has a convex portion  75  projecting beyond the inner side of the convex portion  69 , as shown in  FIG. 7 . When the male base  60  is combined with female base  40 , the convex portion  75  of the male terminal  70  may be engaged with and below the contact  54  of the female terminal  50 , and the laterally and elastically movable force arm  512  of the female terminal  50  is elastically and inwardly movable. 
     As shown in  FIGS. 8 and 9 , the third embodiment of the invention is substantially the same as the second embodiment except that the extension  71  of the male terminal  70  of this embodiment has the convex portion  75  projecting beyond the outer side of the convex portion  69 . When the male base  60  is combined with female base  40 , the convex portion  75  of the male terminal  70  is engaged with the concave portion  45  of the female base  40 . 
     As shown in  FIGS. 10 and 11 , the fourth embodiment of the invention is substantially the same as the third embodiment except that the fixing portion  72  of the male terminal  70  of this embodiment is similar to the first embodiment and transversally and horizontally extends and is fixed to the fixing slot  621 , the cut surface of the distal end of the extension  71  is the vertical contact  74 , which laterally communicates with the concave portion  61 . The plate surface of the distal section of the laterally and elastically movable force arm  512  of the extension  51  of the female terminal  50  is bent reversely downwards and slantingly projects toward the fitting slot  41 , and the plate surface is again bent to form the contact  54 . The contact  54  is a slightly inclined flat surface. When the contact  74  of the male terminal  70  laterally elastic rests against the contact  54  of the female terminal, the laterally and elastically movable force arm  512  of the female terminal is elastically and inwardly movable so that the contact  54  is turned into the vertical surface and contacts with the contact  74  of the male terminal  70  with the larger area. 
     In addition, each of two sides of the bottom of the middle portion  46  of the female base  40  has a limiting surface  47 . The horizontal force arm  511  of the female terminal  50  rests against and is positioned on the limiting surface  47 . 
     This embodiment further has the following technological features. That is, the contact  74  of the male terminal  70 , which is not elastically movable, is the rougher cut surface having the better scratching effect. The contact  74  of the elastically movable female terminal  50  is the smooth plate surface. The electrically connection effect between the cut surface and the smooth plate surface is the best. 
     As shown in  FIGS. 12 and 13 , the fifth embodiment of the invention is substantially the same as the first and fourth embodiments except that the male terminal slot of the male base  60  of this embodiment has the vertically extending fixing slot  621 . The contact  54  of the female terminal  50  is a bump formed by bending the plate surface. The distal end of the extension  51  can rest against the limiting surface  47 . The male terminal  70  is also formed by bending the plate surface of the metal sheet, and is integrally formed with an extension  71 , a fixing portion  72  and a pin  73 . The extension  71  has the vertically extending vertical section, and two sides of the vertical section are formed with the fixing portion  72 . The cut surface of the distal end of the vertical section is the contact  74 . The fixing portion  72  is vertically fixed, from top to bottom, to the fixing slot  621  of the male terminal slot. So, the extension is not elastically movable. The contact  74  is exposed from the bottom end of the male base  60  and vertically elastically rests against the contact  54  of the female terminal  50 . The pin  73  is connected to the extension  71  and has the end section horizontally extending out of the male base  60 . 
     As shown in  FIGS. 14 to 17 , the sixth embodiment of the invention is a board-to-board electrical connector comprising a female base  40 , female terminals  50 , a male base  70 , male terminals  80 , four female lugs  80 , four male lugs  85  and an engaging device. 
     The female base  40  is made of an insulating plastic material and has a middle formed with depressed fitting slot  41 , wherein the fitting slot  41  is a single slot. 
     The female terminals  50  in two rows are arranged on two sides of the fitting slot  41  of the female base  40  to form a female connector. Each female terminal  50  is partially embedded into the female base  40  and integrally injection molded. The female terminal  50  is formed by bending the plate surface of the metal sheet and integrally formed with an extension  51 , a fixing portion  52  and a pin  53 . The fixing portion  52  transversally and horizontally extends and is embedded into the female base and fixed. The extension  51  has a first portion  513  and a second portion  514 . One end of the first portion  513  is connected to one end of the fixing portion  52  and transversally and horizontally extends to the transversal middle point of the female base. The second portion  514  is bent reversely from the other end of the second portion  513 , and is inclined and extends upwards to the fitting slot  41 . One end of the first portion  513  connected to the second portion  514  is fixed to the female base  50 , and the connection ends of the first and second portions are stacked. The reversely bent second portion  514  is an inclined force arm, which is elastically and vertically movable and has a distal-end cut surface, which is most convex upwards contact  54 . The contact  54  is the natural arc or deburred chamfer formed upon pressing. The female base has an empty region above the first portion  513  vertically corresponding to the elastically movable portion of the second portion  514 . The maximum width of the first portion  513  is greater than the maximum width of the second portion  514 . The first portion  513  can vertically completely cover the elastically movable portion of the second portion  514 . Two sides of the first portion  513  is covered by the material of the female base so that the empty region is formed with a bottom surface and is flush with the first portion  513 . The bottom surface of the empty region is the bottom surface of the fitting slot  41 . The pin  53  has a horizontal end section, and the pins  53  of the two rows of female terminals extend out of two sides of the female base  40 , respectively. 
     The male base  60  is made of an insulating plastic material and is a single convex portion mounted in the fitting slot  41  of the female base  40 . Each of two sides of the bottom surface of the male base  60  is formed with one row of slots  610 . 
     The male terminals  70  in two rows are arranged on two sides of the male base  60  to form a male connector. Each male terminal  70  is partially embedded into the male base and is integrally injection molded. The male terminal  70  is formed by bending the plate surface of the metal sheet, and is integrally formed with an extension  71  and a pin  73 . The extension  71  has a U shape. The extension  71  is also the fixing portion and substantially partially embedded into the male base  60  and fixed with only the top and bottom plate surfaces being exposed. So, the extension  71  is not elastically movable, and the bottom plate surface of the horizontal section of the bottom end is the contact  74 , which is exposed and flush with the bottom surface of the slot  610 . The contact  74  vertically elastically rests against the contact  54  of the female terminal  50 . The pin  73  is connected to the extension  71  and has a horizontal end section, and the pins of the two rows of male terminals extend out of two sides of the male base  60 . 
     The contacts  74  and  54  of the male and female terminals are the only mutual contacting and conducting portions of the male and female terminals. 
     The four female lugs  80  are fixed to two sides of the female base  40  and are disposed on the outer ends of the two rows of female terminals  50 . The female lug  80  has a fixing portion and a pin, and is substantially the same as the fixing portion and the pin of the female terminal. The fixing portion also transversally and horizontally extends and is embedded into the female base  40  and fixed. The end section of the pin also horizontally extends out of the female base  40 . 
     The four male lugs  85  are fixed to two sides of the male base  60  and disposed on the outer ends of the two rows of male terminals  70 . The male lug  85  has a fixing portion and a pin and is substantially the same as the fixing portion and the pin of the male terminal. The fixing portion vertical extends and is embedded into the male base  60  and fixed. The pin also horizontally extends out of the male base  60 . 
     The engaging structure makes the male base  60  be combined and engaged with the female base  40 , so that the contact  74  of the male terminal  70  elastically rests against the contact  54  of the female terminal  50 . The engaging structure is integrally formed with the first engaging portion on two sides of the bottom end of the male base  60 , and integrally formed with the second engaging portion on two sides of the fitting slot  41  of the female base  40 . The first and second engaging portions are transversal projections engaging with the slots. The first engaging portion comprises transversal projecting projections  64 . The top and bottom ends of the projection  64  are formed with bevel guides. The projections  64  are transversal and vertically correspond to the gaps between the adjacent male terminals  70 . The male base  60  is vertically staggered with the projections  64 . The second engaging portion comprises the transversal fitting concave portions  45 . The concave portions  45  are transversal and vertically correspond to the gaps between the adjacent female terminals  50 . The top vertically corresponding to the concave portion  45  has the top engaging surface  44  and the bottom surface of the lower corresponding female base is formed with through holes  413 . 
     As shown in  FIG. 16 , when the male base  60  is combined with female base  40 , the contact  74  of the male terminal  70  vertically and elastically rests against the contact  54  of the female terminal  50 , the projections  64  of the male base  60  are engaged with the concave portions  45  of the female base  40  to prevent the male and female bases  60  and  40  from separating from each other. As shown in  FIG. 14 , each of two outer ends of the one row of female terminals  50  on two sides of the female base  40  has a vertically extending groove  49 . The groove  49  can make the two side portions of the fitting slot  41  be easily and elastically movable to facilitate the projections  64  of the male base  60  in engaging with the concave portions  45  of the female base  40 . 
     The pins  73  of the male terminals  70  are electrically connected to the bonding pad  331  of the first circuit board  33 . The pins  53  of the female terminals  50  are electrically connected to the bonding pads  341  of the second circuit boards  34  so that the first circuit board  33  is electrically connected to the second circuit board  34 . 
     Upon manufacturing, the male and female terminals and the male and female lugs are pressed in the manner the same as that of the first embodiment. So, the platingless layer section  81  of the female lug  80  and the platingless layer section  56  of the female terminal  50  have the same height, and the platingless layer section  86  of the male lug  85  and the platingless layer section  76  of the male terminal  70  have the same height. 
     According to the above-mentioned description, this embodiment has the advantages of the first embodiment and the following additional advantages. 
     First, the bottom surface of the fitting slot  41  has the better structural strength by the combination of the first portion  513  of the extension of the female terminals  50 , so that the small sized plastic base having the better structural strength can be provided. 
     Second, the first portion  513  of the extension of the female terminal  50  can completely cover the elastically movable portion of the second portion  514  in the vertical direction, and the concave portions  45  transversally and vertically corresponds to the gaps between the adjacent female terminals  50 . Also, the top of the concave portion  45  has the top engaging surface, and the bottom thereof corresponding the bottom surface of the female base  40  is formed with through holes  413 . So, the female base  40  can be directly injected molded using the top and bottom molds combined together without using the slider. The manufacturing processes are simplified. 
     As shown in  FIGS. 18 to 21 , the seventh embodiment of the invention is substantially the same as the sixth embodiment except that the middle of the female base  40  of this embodiment has a projecting middle portion  46 , so that the fitting slot  41  comprises two concave portions on two sides of the middle portion. The middle of the male base  60  has a concave portion  61  so that the two sides are formed with convex portions  69 . Each of two sides of the concave portion  61  is formed with one row of slots  610 . The concave portion  61  of the male base corresponds to and is fit with the middle portion  46  of the female base  40 . The convex portion  69  on two sides of the male base corresponds to and is fit with the fitting slot  41  of the female base in the form of two concave portions. The first portion  513  of the extension  51  of the female terminal  50  extends to the middle portion  46 . The second portion  514  is first bent reversely upwards from one end of the first portion  513 , and then bent reversely and outwardly downwards to form the laterally and elastically movable force arm. The distal-end cut surface of the extension  51  is the contact  54 . The second portion  514 , which most projecting outwards, is the contact  54 . The connection ends of the first and second portions  515  of the extension  51  are stacked and embedded into the middle portion  46  of the female base  50  and are fixed. The extension  71  of the male terminal  70  is also the fixing portion fixed to the male base  60 . The extension  71  has a vertical section and an end section bent reversely. The inner plate surface of the vertical section is the contact  74 . The end section of the extension  71  is bent reversely so that the lower end is the plate surface but is not the cut surface. 
     As shown in  FIG. 20 , when the male base  60  is combined with the female base  40 , the contact  74  of the male terminal  70  laterally and elastically rests against the contact  54  of the female terminal  50 , and the second portion  514  of the female terminal  50  is elastically and inwardly movable. 
     As shown in  FIGS. 22 to 28 , the eighth embodiment of the invention is substantially the same as the seventh embodiment except that each of two sides of the fitting slot  41  of the female base  40  of this embodiment is formed with one row of projections  410 . The bottom of the projection  410  is formed with a transversal fitting concave portion  45 . The concave portions  45  transversally correspond to the extensions  51  of the female terminals  50  and are vertically staggered with the fixing portion  52  of the female terminals  50 . The concave portions  45  are formed with through holes  413  vertically corresponding to the bottom surface of the female base  40 . The fixing portion  52  of the female terminal  50  has the turning portion  521  disposed in the gap between the adjacent through holes  413 . The turning portions  521  and the extensions  51  are transversally staggered without overlapping. The bottom plate surface of the first portion  513  of the extension of the female terminal  50  is flush with the bottom surface of the female base  40 . Thus, the empty region of each female terminal  50  is lower than the bottom surface of the fitting slot  41 . The female base  40  has partition baffles  411  for partitioning the portions of the empty region of each female terminal  50  lower than the fitting slot  41  into slots  412 . The partition baffles  411  can strengthen the structure of the female base. The transversally projecting projections  64  of the male base  60  transversally correspond to the contacts  74  of the male terminals  70  and are vertically staggered with the male terminals  70 . The transversally projecting projections  64  are formed with through holes  611  vertically corresponding to the male base. The extension  71  of the male terminal  70  has a horizontal turning portion  711  and is disposed in the gap between the adjacent through holes  611 . The turning portion  711 , the contact  74  and the pin  73  are transversally staggered without overlapping. 
     According to the above-mentioned structure, this embodiment further achieves the following effects. 
     First, the male base  60  and the male terminal  70  may be injected molded by combing the top and bottom molds, and the engaging block  64  transversally corresponds to the contact  74  of the male terminal  70 . The female base  40  and the female terminal  50  may also be injected molded by combining the top and bottom molds, and the concave portion  45  transversally corresponds to the contact  54  of the female terminal  50 . Thus, the male and female connectors of this embodiment can be connected to the conventional male and female connectors. 
     Second, the bottom plate surface of the first portion  513  of the extension of the female terminal  50  is flush with the bottom surface of the female base  40 , so that the height of the female base  40  can be decreased. 
     Third, the female base  40  has the partition baffles  411  for partitioning the empty region of the each female terminal  50  and strengthening the structure of the female base. 
     As shown in  FIGS. 29 and 30 , the ninth embodiment of the invention is substantially the same as the eight embodiment except that the engaging block  64  of the male base  60  of this embodiment vertically corresponds to the top surface of the male base  60 . Thus, a slider is needed upon injection molding using top and bottom molds combined together. In addition, the rear section  712  of the extension of the male terminal is bent to be horizontal. 
     As shown in  FIG. 31 , when the female connector of this embodiment is connected to the conventional male connector  170 , the engaging block  172  of the male terminal  171  of the conventional male connector  170  can be transversally engaged into the concave portion  45  of the female base  40  of this embodiment. 
     As shown in  FIG. 32 , when the male connector of this embodiment is connected to the conventional female connector  180 , the transversally projecting engaging block  182  of the female terminal  181  of the conventional female connector  180  may be engaged with the top of the projection  64  of the male base  60  of this embodiment. 
     As shown in  FIG. 33 , the tenth embodiment of the invention is substantially the same as the sixth and eighth embodiments. 
     As shown in  FIG. 34 , the eleventh embodiment of the invention is substantially the same as the seventh and tenth embodiments. 
     As shown in  FIGS. 35 and 36 , the twelfth embodiment of the invention is substantially the same as the eleventh embodiment except that the first portion  513  of the extension of the female terminal  50  and the plate surface of the second portion  514  of this embodiment have the same width. The empty region of each female terminal  50  has no bottom surface and is formed with through holes. The female base  40  has partition baffles  411  for partitioning the empty region of the each female terminal  50  to form through holes  414 . 
     As shown in  FIG. 37 , the thirteenth embodiment of the invention is substantially the same as the twelfth embodiment except that the bottom plate surface of the first portion  513  of the extension of the female terminal  50  of this embodiment is higher than the bottom surface of the female base  40 . 
     As shown in  FIG. 38 , the 14th embodiment of the invention is substantially the same as the ninth embodiment except that the engaging block  64  of the male base  60  of this embodiment is projectingly disposed on two sides and integrally longitudinally horizontally extends between one row of male terminals  70 , so that the manufacturing processes are simplified. 
     As shown in  FIG. 39 , the 15th embodiment of the invention is substantially the same as the ninth embodiment except that the rear section of the second portion  514  of the extension of the female terminal  50  of this embodiment is bent downwardly and reversely, stacked and then open with an inclined angle. Similarly, the distal end is formed with the contact  54 . In addition, two sides of the female base have partition baffles  415  to strengthen the structure. 
     As shown in  FIGS. 40 to 43 , the electrical connector according to the 16th embodiment of the invention is connected to a bus line or a flexible circuit board and includes a base  90 , terminals  100  and  100 ′, an upper metal cover  110  and a pressing member. 
     The base  90  is made of a plastic material and has a depressed fitting slot  91 . The fitting slot  91  extends to the front end of the base  90  and is open and in the form of an inlet facing frontwards. Two rows of front-to-rear staggered slots  93  are disposed on the bottom surface of the fitting slot  91 . The adjacent slot  93  is partitioned by the partition baffle  92 . One row of longitudinal positioning slots  94  are disposed in back of the fitting slot  91  and near the back end of the fitting slot  91 . The extending direction of the longitudinal positioning slot  94  is perpendicular to the bottom surface of the fitting slot  91 . The one row of longitudinal positioning slots  94  and the rear row of slots  93  are front-to-rear staggered. That is, a longitudinal positioning slot  94  is disposed between any two adjacent rear rows of slots  93 . Two sides of the fitting slot  91  are formed with the higher sliding slots  95 . A stop surface  97  and a downward concave portion  96  are disposed near the front end of the sliding slot  95 . The rear section of the sliding slot  95  has an upward convex portion  98 . 
     The terminals are arranged on the base  90  with the terminal gap of 0.3 mm. Each terminal is partially embedded into the base  90  and integrally injection molded. The terminals comprise one row of terminals  100  having rear output pins and one row of terminals  100 ′ having front output pins. Each of the one row of terminals  100  and the one row of terminals  100 ′ has the terminal gap of 0.6 mm. The one row of terminals  100  and the one row of terminals  100 ′ are arranged alternately, so the overall terminal gap is equal to 0.3 mm. The terminal  100  is formed by bending the plate surface of the metal sheet, and is integrally formed with an extension  101 , a fixing portion  102  and a pin  103 . The fixing portion  101  transversally and horizontally extends and is embedded into the plastic base  30  and fixed. The extension  101  has a first portion  104  and a second portion  105 . One end of the first portion  104  is connected to one end of the fixing portion  102  and transversally horizontally frontwardly extends through the front end of one slot  93  of the front row of the base  90 . The second portion  105  is bent reversely from the other end of the first portion  104 , is inclined upwardly and extends from the slot  93  to the fitting slot  91 . The connection ends of the first and second portions  107  are stacked and embedded into the base  90  and fixed. The reversely bent second portion  105  is in the form of an inclined force arm, which is vertically elastically movable in the slot  93  and has an distal-end cut surface that is most convex upward the contact  106 . The plastic base has an empty region above the first portion  104  vertically corresponds to the elastically movable portion of the second portion  105 . The maximum width of the first portion  104  is greater than the maximum width of the second portion  105 . The first portion  104  can vertically completely cover the elastically movable portion of the second portion  105 . Two sides of the first portion  104  are covered by the plastic base so that the empty region is formed with a bottom surface flush with the first portion  104 . The bottom surface of the empty region is the bottom surface of the slot  93 . The end section of the pin  103  horizontally extends out of the back end of the base  90 . The terminal  100 ′ and the terminal  100  have substantially the same structure except that the end section of the pin  103  of the terminal  100 ′ horizontally extends out of the front end of the base  90 . The second portion  105  of the extension of the terminal  100 ′ is disposed in the rear row of slot  93  of the base  90 . The end section of the second portion  105  is again bent reversely, so the contact  106  of the one row of terminals  100  and the contact  106  of the one row of terminals  100 ′ are inclined backwards and are arranged alternately in the front-to-rear direction. 
     The two rows of front-to-rear staggered slots  93  are the elastically movable space of the second portions  105  of the two rows of terminals  100  and  100 ′, respectively. 
     The upper metal cover  110  is assembled with and fixed to the base  90 , and has a top surface  111  and two side surfaces  112  to form an inverse U shape. The front end of the top surface  111  has a notch  113 , and the back end of the top surface  111  is bent downwardly to form a rear surface  114 . The plate surface of the rear section of the top surface  111  prodded vertically bent downwardly to form one row of longitudinal positioning sheets  115 , which are engaged with one row of longitudinal positioning slots  94  of the base  90 . The top surface  111  is disposed above the fitting slot  91 , so that the front end of the fitting slot  91  is formed with an insertion port, into which a bus line or a flexible circuit board may be inserted. 
     The pressing member is disposed between the base  90  and the upper metal cover  110 . The pressing member is a sliding plate  120  capable of sliding in the front-rear direction relatively to the base  90 . The sliding plate  120  is formed by bending a metal plate sheet to form a flat-body like pressing portion  121 . Two sides of the back end of the pressing portion  121  have backwardly projecting convex portions so that the back end of the pressing portion  121  becomes a concave portion  124 . The outer side of the convex portion is formed with a projecting engaging portion  122 . The front end of the pressing portion  121  is formed by folding a metal plate sheet to form a thicker operation portion  123 . The plate surface of the pressing portion  121  is downwardly pressed to form two ribs  125 . Two sides of the pressing portion  121  rest against the sliding slot  95  of the base  90 . When the sliding plate  120  slides the innermost end of the sliding slot  95 , the operation portion  123  is still exposed outside the upper metal cover  110  and connected to the notch  113 , and the engaging portion  112  can be positioned at the back end of the convex portion  98 . When the sliding plate  120  slides out, the stop surface  37  of the base  90  can stop the engaging portion  122 . 
     According to the above-mentioned structure, as shown in  FIG. 44 , the bus line or flexible circuit board  160  can be inserted from the front end of the base  90  into the fitting slot  91  for electrical connection. When the sliding plate  120  slides into the fitting slot  91 , the pressing portion  121  tightly rests against the bus line or flexible circuit board  160 . As shown in  FIG. 45 , when the sliding plate  120  slides out, the engaging portion  122  falls into the concave portion  96  so that the sliding plate  120  can be lifted upwards and the pressing portion  121  cannot press the bus line or flexible circuit board  160 . At this time, the bus line or flexible circuit board  160  can be frontwardly taken out. 
     In addition, the electrical connector may also have the single-row terminal configuration having one row of terminals having only rear output pins. 
     As shown in  FIGS. 46 to 50 , the 17th embodiment of the invention is substantially the same as the 16th embodiment except that the middle of the rear section of the base  90  has an upward convex surface  922 . Three horizontal positioning slots  920  are formed below the convex surface  922 . 
     The upper metal cover  110  is assembled and positioned on the base  90  from front to rear. The rear section of the top surface  111  of the upper metal cover  110  is pressed and bent downwardly by a height to form three horizontal positioning sheets  1120  horizontally backwardly extended and engaged with three horizontal positioning slots  920 . Each of two sides of the top surface  111  is pressed to form a front-to-rear extending elastic sheet  1122 . The front end  1123  of the elastic sheet  1122  is inclined downwards and bent into the concave portion  96  of the base  90 . 
     The second portions  105  of the extensions  101  of the two rows of terminals  100  and  100 ′ are prodded from the plate surface of the first portion  104  and slantingly projects upwards. The second extensions  105  of the two rows of terminals  100  and  100 ′ extends forwards and backwards along the inserting direction of the bus line. The top surfaces of the first portions  104  of the two rows of terminals  100  and  100 ′ are flush with the bottom surface of the slot  93 , and the bottom surface and peripheral sides thereof are embedded and fixed into the base  90 , and are thus covered and fixed by the material of the base. The portions of the two slots  93  vertically corresponding to the second portions  105  are empty. 
     Each of two sides of the front section of the pressing portion  121  of the sliding plate  120  is formed with an engagement hole  1210 . The convex portion  1211  projects backwardly by a greater length, so the convex portion  1211  has the reinforcing rib  125 . 
     As shown in  FIGS. 48 and 49 , when the sliding plate  120  is inserted into the fitting slot  91 , the front end  1123  of the elastic sheet  1122  is engaged into the engagement hole  1210  and locks with the sliding plate  120 . As shown in  FIG. 50 , when the sliding plate  120  is pulled out of the fitting slot  91 , the convex portion  1211  on the back end of two sides of the sliding plate  120  is moved to the concave portion  96  and is downwardly pressed down by the front end  1123  of the elastic sheet so that the sliding plate  120  is in an upward tilted state. 
     As shown in  FIG. 51 , the 18th embodiment of the invention is substantially the same as the sixth embodiment except that the embedding and injection molding structure of the female terminal  50  and the female base  40  is the same as the 17th embodiment. That is, the second portion  514  of the extension  51  of the female terminal  50  is formed by prodding the plate surface of the first portion  513  upwardly and projectingly. 
     As shown in  FIGS. 52 and 53 , the 19th embodiment of the invention is substantially the same as the 16th embodiment except that the overall length of one row of terminals  100 ′ having front output pins is substantially the same as the plate width. The two rows of terminals  100  and  100 ′ and the insulation base  30  are embedded and injection molded. The front section of the fitting slot  91  of the base  90  is a slot  93 , the bottom surface thereof is combined with the first extension  104  of the terminal  100 , and the rear section thereof is a through hole  930 . However, the front and back ends of the through hole  930  are still combined through the fixing portions  102  of the one row of terminals  100  having rear output pins to enhance the structural strength. 
     As shown in  FIG. 54 , the 20th embodiment of the invention is substantially the same as the 19th embodiment except that the pressing member is a pivot member  130  formed by bending a metal plate. The front ends of the first portions  104  of one row of terminals  100  having rear output pins are combined and fixed with the base  90  and are flush with the bottom surface of the fitting slot  91 . Partitions  36  are provided to partition the adjacent terminals. The first portion  104  extends to the frontmost end of the base  90  so that the second portion  105  has the longer force arm. 
     While the present invention has been described by way of examples and in terms of preferred embodiments, it is to be understood that the present invention is not limited thereto. To the contrary, it is intended to cover various modifications. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications.