Abstract:
A wire to board connector assembly includes mating first and second connectors. The board (second) connector is configured for surface mounting to a circuit board and contains a plurality of surface mount terminals with a pair of contact arms defining a mating slot therebetween. The other, mating (first) connector includes a plurality of box-style terminals that are supported and restrained in place within a first connector housing. Projections are dispose in the first connector housing and extend lengthwise along the direction of the terminals and provide support for the terminals. Locking members are formed as part of the first housing and reliably engage the second housing.

Description:
REFERENCE TO RELATED APPLICATIONS 
     The Present Disclosure claims priority to prior-filed Japanese Patent Application No. 2009-122026, entitled “Wire-To-Board Connector And Wire Connector,” and filed 20 May 2009, the contents of which is fully incorporated in its entirety herein. 
     BACKGROUND OF THE PRESENT DISCLOSURE 
     The Present Disclosure relates generally to a wire-to-board connector and a wire connector, and more specifically to such a connector assembly having a low height and reliable locking structure. 
     Previously, wire-to-board connectors have been used for connecting electrical wires of a cable to a circuit board such as described in Japanese Patent Application No. 2007-220422. Such a wire-to-board connector has a board connector mounted on the circuit board and engaged by fitting with a wire connector which is connected to an end portion of an electrical wire. 
       FIG. 16  is an exploded perspective view of a wire connector according to the prior art, in which a wire connector  801  is engaged by a board connector (not shown). A terminal  851  is connected to a termination end of an electrical wire  891  and attached to a housing  811  of the wire connector  801 . The housing  811  is formed with a terminal-insertion hole  814 , and the terminal  851  is press-fit into the terminal-insertion hole  814 . In this way, by fitting the wire connector  801  having the terminal  851  attached thereto so as to be engaged with the board connector, the wire  891  can be connected to a circuit board on which the board connector is mounted, also not shown. Moreover, a locking projection  816  is formed on the housing  811 , and this projection  816  is engages a locking portion of the board connector, whereby a stable engagement state can be maintained. 
     However, in the above-described conventional wire-to-board connector, when the wire  891  is pulled with a strong force when the wire connector  801  and board connector are tightly engaged, there may occur an unfavorable occurrence of the terminal  851  coming loose and pulled from the terminal-insertion hole  814 . In order to prevent the removal of the terminal  851 , it may be helpful to form a locking projection, called a lance, on an inner wall of the terminal-insertion hole  814  so that the terminal  851  is locked at the latching projection. However, in recent years, connectors have become miniaturized along with the miniaturization of electronic components, devices, and apparatuses. Therefore, the locking projection also has to be extremely small, and moreover, there is a concern that the locking projection itself may be broken when the electrical wire  891  is pulled with a strong force. 
     The housing  811  which is made of resin is molded, for example, by a molding method that causes molten resin to flow into a mold, like an injection molding. Therefore, the locking projection projected from the inner wall of the terminal-insertion hole  814  is positioned at the inner side of the housing  811 , and is thus distant from a gate portion, which is the entrance port of the molten resin into the mold, and is the end point of the flow of the molten resin. For this reason, in such a locking projection, weld lines (sometimes, referred to simply as “welds”) are likely to occur at the converging positions of the flows of the molten resin. In particular, since locking projections are very small and thin, the weld lines are likely to extend in a direction of crossing a cross section thereof. 
     Moreover, since the weld lines represent interfaces formed because two or more flows of molten resin are unable to reunite, the strength thereof is low. Therefore, when a strong force that pulls the wire  891  is applied to the locking projection via the terminal  851 , the locking projection will easily brake at the weld lines. Particularly, when the weld lines are formed at the base end of the locking projection and the vicinity thereof, substantially the entire portions of the locking projection will be lost by the breakage, and thus, the terminal  851  will be removed and extracted from the terminal-insertion hole  814 . 
     It is difficult to prevent the occurrence of the weld lines, and also difficult to control the locations or the extending directions of the weld lines. Particularly, in recent years, the wire connector  801  has been miniaturized and the respective parts of the housing  811  have been made thinner along with the miniaturization of electronic devices and apparatuses. Therefore, it is extremely difficult to control the flow of molten resin so as to prevent the occurrence of weld lines in the locking projection. 
     SUMMARY OF THE PRESENT DISCLOSURE 
     Therefore, it is an object of the present invention to solve the above-described problems and provide a wire-to-board connector and wire connector having a configuration such that a locking projection portion has an appropriate shape for enabling the prevention of the occurrence of weld lines at the base end of the locking projection portion or the vicinity thereof. As a result, it is possible to more stably hold the terminal secured to the housing while reliably preventing the removal of the terminal, thereby realizing a simple structure with low height so that the miniaturization of a wire-to-board connector and wire connector is effected. Accordingly, the wire-to-board and wire connector allow easy production with a simple structure and high reliability in operation with a small number of parts and low production costs. 
     Therefore, a wire-to-board connector according to the present invention includes a first connector having a first insulative housing and a first terminal connected to a termination end of a wire fitted in the first housing, where the first connector has a fitting face extending in a direction intersecting an extending direction of the first terminal; and a second connector having a second insulative housing and second terminal fitted in the second housing and configured to contact with the first terminal, with the second connector configured for surface-mounting to a circuit board and for engaging with the first connector and having a fitting face intersecting the top surface of the board, wherein: the first housing is provided with a first terminal receiving concave portion configured to be opened to a rear end face opposing the fitting face and a locking projection portion which is arranged in the first terminal accommodation-concave portion and is formed therein with a groove portion extended in the direction of the first terminal; and, the first terminal is provided with a first contacting distal end portion configured to make contact with the second terminal and a locking piece which is formed on the first contacting distal end portion and configured to be locked at a front end face of the locking projection portion, where the first terminal is inserted to be fitted into the first terminal accommodation-concave portion from the side of the rear end face. 
     The wire-to-board connector according to another embodiment has a configuration such that the locking projection portion has a base end thereof which is connected to a first body portion of the first housing and extended in the direction of the fitting face, and has a distal end thereof having a locking block portion formed thereon, and the groove portion being formed on a surface of the locking projection portion located further rearward than the locking block portion, where the locking projection portion has a channel shape having a cross-section in the form of substantially squared U-shape. 
     The wire-to-board connector according to a further embodiment has a configuration such that the groove is extended to pass through the first body portion and opened to the rear end face. The wire-to-board connector according to a still further embodiment has a configuration such that the locking projection portion is provided with a ceiling portion and side portions on both left and right sides thereof, where the ceiling and side portions define circumferential surfaces of the groove portion, and the thickness dimension of each side portion is equal to or larger than the thickness dimension of the ceiling portion. 
     The wire-to-board connector according to a still further embodiment has a configuration such that a sloped portion is formed on portions of the groove portion connected to the locking block portion so that a cross-sectional area of the sloped portion increases gradually from the groove portion to the locking block portion. Moreover, a wire connector according to the disclosure includes an insulative housing and a terminal connected to a wire termination end fitted in the housing, where the wire connector has a fitting face extending in a direction intersecting the extent of the terminal, wherein: the housing is provided with a terminal-receiving, concave cavity configured to open to a rear end face opposing the fitting face, and a locking projection portion which is arranged in the terminal cavity and which is formed with a groove portion extending in the direction of the terminal; and, the terminal is provided with a contacting distal end portion configured to contact with a counterpart terminal of a mating connector, and a locking piece which is formed on the contacting distal end portion and configured to be locked at a front end face of the locking projection portion, where the terminal is inserted to be fitted into the terminal cavity from the side of the rear end face. 
     The wire connector according to another embodiment has a configuration such that the locking projection portion has a base end thereof which is connected to a housing body portion and extends in the direction of the fitting face and further has a distal end thereof having a locking block portion formed thereon, and the groove portion being formed on a surface of the locking projection portion further rearward than the locking block portion, wherein the locking projection portion has a channel shape having a cross-section in the form of substantially squared U-shape. 
     In accordance with the present invention, the wire-to-board and wire connector have a configuration in which the locking projection portion has an appropriate shape to enable the prevention of the occurrence of weld lines at the base end of the locking projection portion or the vicinity thereof. Due to such a configuration, the terminal is firmly secured in the housing while the removal thereof is reliably prevented, thereby providing a simple low height structure. Accordingly, it is possible to provide a wire-to-board connector and a wire connector which can be easily produced to have a simple structure with a small number of parts and low production costs. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The organization and manner of the structure and operation of the Present Disclosure, together with further objects and advantages thereof, may best be understood by reference to the following Detailed Description, taken in connection with the accompanying Figures, wherein like reference numerals identify like elements, and in which: 
         FIGS. 1A and 1B  are top perspective views of a wire to board connector of the invention; 
         FIGS. 2A-2C  are further views of the connector of  FIG. 1A ; 
         FIG. 3  is a sectional view of the connector of  FIG. 2C  taken along line A-A thereof; 
         FIG. 4  is a top sectional view of the connector of  FIG. 2C , taken along line B-B thereof; 
         FIG. 5  is a perspective view of the first terminal terminated to a wire; 
         FIG. 6  is a top sectional view of the first connector of  FIG. 1A , with the first terminal removed therefrom, and illustrating the same cross section as  FIG. 4 ; 
         FIG. 7  is a bottom front perspective view of a locking projection portion of the connector; 
         FIGS. 8A-8B  are views of the locking projection of  FIG. 7 ; 
         FIGS. 8C-8E  are cross-sectional views of the locking projection of  FIG. 8A , taken along Lines C-C, D-D and E-E, respectively, thereof; 
         FIGS. 9A-9B  are top perspective views of a board-mounted, mating connector according to the disclosure; 
         FIGS. 10A-10B  are views of the connector of  FIG. 9A  mounted to a circuit board; 
         FIG. 11  is a sectional view of the mating connector of  FIG. 10A , taken along line F-F thereof; 
         FIG. 12  is a perspective view of a terminal used in the mating connector of  FIG. 9A ; 
         FIGS. 13A-13B  are view of the connectors of  FIGS. 1A and 9A , mated together; 
         FIG. 14  is a top plan view of the connectors of  FIG. 9A ; 
         FIG. 15  is a sectional view of  FIG. 14 , taken along line G-G; and 
         FIG. 16  is an exploded perspective view of a conventional wire connector. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     While the Present Disclosure may be susceptible to embodiment in different forms, there is shown in the Figures, and will be described herein in detail, with the understanding that the disclosure is to be considered an exemplification of the principles of the Present Disclosure, and is not intended to limit the Present Disclosure to that as illustrated. Moreover, in the Present Disclosure, directional representations—i.e., up, down, left, right, front, rear and the like, used for explaining the structure and movement of the various elements of the Present Disclosure, are relative. These representations are appropriate when the elements are in the position shown in the Figures. If the description of the position of the elements changes, however, it is assumed that these representations are to be changed accordingly. 
     In the drawing figures, a first connector used as a wire connector, which is one from a pair of connectors constituting a wire-to-board connector according to the present embodiment and generally designated by reference numeral  1 , is a connector which is connected to a termination end of a cable that encloses a plurality of wires  91 . The first connector  1  is mated to a mating second connector  101  as a counterpart connector of the pair of connectors constituting the wire-to-board connector according to the present embodiment. The second connector  101  is a surface-mounted board connector which is mounted on a surface of a circuit board  191 . In drawings, although the number of wires  91  is two, the number of wires  91  may be one, or three, or more. 
     The wire-to-board connector includes the first connector  1  and the second connector  101 , and is configured to connect the wires  91  and board  191  together. It will be described that: the wires  91  are parts of power supply lines; end portions of the electrical wires  91  opposite the first connector  1  are connected to a non-illustrated power supply; and the first connector  1  and the second connector  101  are connectors for connecting the power supply lines of the board  191 . However, the wires  91  may be parts of signal lines, and the first connector  1  and the second connector  101  may be used as connectors for connecting signal lines together. Moreover, the board  191  is typically a printed circuit board used in an electronic device or apparatus and may be silicon boards or silicon carbide boards having an electronic device or apparatus arranged directly thereon or may be any type of boards. Furthermore, examples of the electronic device or apparatus include a personal computer, a cellular phone, a digital TV, a car navigation device, and a games machine and the like; however, the type of devices and apparatuses is not intended to be particularly limited. 
     The first connector  1  includes a first housing  11  as a housing which overall has a generally flat rectangular parallelepiped shape and is made of an insulating material such as plastic. First conductive terminals  51  are fitted in the first housing  11 . In the example illustrated in the drawing figures, although the number of first terminals  51  is two assuming that the power supply lines include one positive line and one negative line, the number of first terminals  51  may be arbitrarily changed to comply with the number of power supply lines. The first terminal  51  is connected to a termination end of a wire  91 . 
     As illustrated in the drawings, the first housing  11  is provided with a first top plate portion  12  used as a top plate portion having a flat-plate shape, a first bottom plate portion  18  used as a bottom plate portion which has a flat plate shape which extends parallel to the first top plate portion  12 , a first body portion  14  that has top and bottom surfaces thereof being defined by the first top and bottom plate portions  12  &amp;  18  and holds therein the first terminals  51 , and a pair of first side wall portions  17 , used as side wall portions, which are arranged on opposing left and right sides of the body portion  14  and extend in the front-to-rear direction (horizontally as shown in  FIGS. 2A and 2B ) of the first connector  1 . Moreover, a first fitting face  11   a  used as a mating, or fitting, face is configured to extend in the extending direction of the first terminals  51  and in a direction (preferably, in a direction perpendicular to) intersecting the first top plate portion  12  and the first bottom plate portion  18 . 
     A first projecting plate portion  22  is used as a projecting plate portion and is configured to extend forwardly, and is connected to a front end of the first bottom plate portion  18 . The first projecting plate portion  22  is formed to extend in the distal end direction from the upper front end of the first bottom plate portion  18  so as to cover an under part of a portion of the first terminal  51  fitted into the first housing  11  and located adjacent to the rear end of a first contacting distal end portion  55  as a contacting distal end portion, thereby functioning used as an insulating distance-procuring member capable of procuring the insulating distance of the first terminal  51 . 
     The first body portion  14  has formed therein, on a rear end face thereof (the left end face in  FIGS. 2A and 2B ), first terminal-receiving-concave portions or cavities,  14   a , which are configured to extend in the distal end direction (the rightward direction in  FIGS. 2A and 2B ) from the rear end face and accommodate therein the first terminals  51 . In the example illustrated in the drawing figures, although the number of first terminal cavities  14   a  is two, respectively, the number of terminal receiving cavities  14   a  may be changed to comply with the number of terminals  51 . 
     Each first side wall portion  17  is connected to one of either of the left and right side faces of the first body portion  14  via a side wall connecting portion  17   a  which is thin and flexible so as to deform about the side wall connecting portion  17   a  with respect to the first body portion  14 . Portions of the first side wall portions  17  located further forward (rightward in  FIGS. 2A and 2B ) than the side wall connecting portion  17   a  are configured as locking arm portions  17   b , and concave engagement portions  17   c , which are configured to engage with later-described laterally convex portions  117   a  of the second connector  101 , are formed on the inner side faces at the distal end portions of the locking arm portions  17   b . Moreover, portions of the first side wall portions  17 , which are located further rearward (leftward in  FIGS. 2A and 2B ) than the side wall connecting portions  17   a , are configured as operating arm portions  17   d . When the engagement between the first connector  1  and the second connector  101  is released, an operator operates by hand the operating arm portions  17   d  to decrease the gap between the left and right operating arm portions  17   d . Due to this operation, the distance between the distal end portions of the locking arm portions  17   b  is increased, so that the engagement between the laterally convex portions  117   a  and the concave engagement portions  17   c  is released and the locking between the first connector  1  and the second connector  101  is released. 
     A first engagement portion  15  is configured to extend in distally from the first body portion  14  so as to engage with the second connector  101 . The first engagement portion  15  is provided with a first engagement top plate portion  15   a  formed even with the first top plate portion  12 , a pair of first engagement side wall portions  15   b  which extend along the edges of the left and right sides of the first engagement top plate portion  15   a  extending downwardly (the lower side in  FIG. 2B ) from the first engagement top plate portion  15   a , and first convex engagement portions  15   c  which have a rod-like shape with a rectangular cross section and are configured to extend along the lower ends of the first engagement side wall portions  15   b , bulge outward from the left and right end faces of the first engagement side wall portions  15   b , and slightly protrude in the distal end direction from the front ends of the first engagement side wall portions  15   b . In other words, the first engagement top plate portion  15   a  can be referred to as a portion of the first top plate portion  12 . 
     A first concave engagement portion, as a concave portion, designated by reference numeral  13  is configured to be engaged with the second connector  101  and has three sides thereof being defined by the first engagement top plate portion  15   a  and the first engagement side wall portions  15   b . In the first concave engagement portion  13 , first terminal restricting portions  16  as terminal restricting members are arranged so as to extend in the distal end direction from the first body portion  14 . The first terminal restricting portions  16  are generally rod-like members having a base end thereof being connected to the first body portion  14  and a distal end thereof being configured as a free end. 
     The distal end portion of each of the first terminal restricting portions  16  has a generally H-shape and includes a beam portion  16   a  which extends in a lateral direction, a lower groove portion  16   b  which has a rectangular cross section with an opened lower surface and is formed on the lower surface side of the beam portion  16   a , and an upper groove portion  16   c  which has a rectangular cross section with an opened upper surface and is formed on the upper surface side of the beam portion  16   a . The beam portions  16   a  are connected to tongue-shaped portions  16   d  which extend toward the base ends of the first terminal restricting portions  16 . 
     The first terminals  51  may be formed by punching sheet metal or the like. As illustrated in  FIG. 5 , each of the first terminals  51  is provided with a conductive wire-connecting, or body portion  53 , a first fixing portion  52  used as a connecting portion connected to the rear end of the wire-connecting portion  53 , and a first contacting distal end portion  55  used as a first contacting arm portion which is connected to the front end of the conductive wire-connecting portion  53 . The conductive wire-connecting portion  53  is a portion which is connected to a core wire used as a conductive wire of the wire  91  and is provided with a core wire-caulking portion  53   a  that caulks so as to fix the core wire. The core wire and the core wire-caulking portion  53   a  may be connected and fixed more securely by applying soldering according as is required. Moreover, the first fixing portion  52  is provided with a wire sealing portion  52   a  that seals to fix the wire  91  from the surroundings of an insulating cladding which covers the perimeter of the core wire. By sealing the wire  91  with portion  52   a , the first terminal  51  may be firmly connected to the termination end of the wire  91 . 
     The first contacting front end portion  55  contacts either one of the second terminals  151  in the second, or mating, connector  101 . The first contacting distal end portion  55  is a channel-shaped portion having a substantially square cross-section opened at one side and extending in the distal end direction from the distal end of the first fixing portion  52 . The first contacting distal end portion  55  includes a top plate portion  55   a  connected to the distal end of the first fixing portion  52 , a bottom plate portion  55   b  extending parallel to the top plate portion  55   a , and a side plate portion  55   c  which connects either the left or right lateral edges of the top plate portion  55   a  and the bottom plate portion  55   b  and extends in the same direction as the extending direction of the top plate portion  55   a  and the bottom plate portion  55   b . Moreover, since the first contacting distal end portion  55  itself has a channel shape having a cross-section in the form of substantially squared U-shape, the first contacting distal end portion  55  has a large secondary section modulus and a high rigidity, and is therefore hardly deformed. 
     As illustrated in  FIG. 3 , when the first terminals  51  are inserted into the first terminal receiving cavity  14   a  from the rear of the first body portion  14  fitted into the first housing  11 , the tongue-shaped portions  16   d  of the first terminal restricting portions  16  are inserted from the side of the distal ends of the first contacting distal end portions  55  into portions disposed between the top plate portions  55   a  and the bottom plate portions  55   b  of the first contacting distal end portions  55 . Due to such a configuration, the vertical displacement of the first contacting distal end portion  55  is restricted, so that the first contacting distal end portion  55  is almost impossible to be displaced in the vertical direction. 
     Moreover, on the top plate portion  55   a  of the first contacting distal end portion  55 , a locking piece  55   d  which is a cut and raised piece is formed so as to be projected further upward (downward, as shown in  FIG. 5 ) than the top plate portion  55   a . The locking piece  55   d  is a cantilever-like member which has elastic properties and has a base end thereof connected to the top plate portion  55   a  and a free end thereof, namely a distal end  55   f , configured to extend obliquely toward the upper rear side. Since the locking piece  55   d  is formed by being cut and raised, a window portion  55   e  used as an opening is defined in the top plate portion  55   a.    
     The first body portion  14  is provided with a lance holding portion  14   b  as a locking projection-holding portion which is arranged above the first terminal accommodation-concave portion  14   a , and a lance  25  used as a locking projection portion is held in the lance holding portion  14   b . The lance  25  is a member which is formed integral with the first housing  11  so as to extend forward from the lance holding portion  14   b  with a base end thereof being connected to the lance holding portion  14   b . The lance  25  is provided with a locking block portion  25   a  which is in mass form and is arranged at a distal end thereof, and as illustrated in  FIGS. 3 and 4 , the distal end  55   f  of the locking piece  55   d  is locked at the front end face  25   h  of the locking block portion  25   a . Due to such a configuration, the first terminals  51  fitted into the first housing  11  are prevented from being removed toward the rear side. 
     On the lower surface of the lance  25 , a groove portion  25   e  is formed at a position located further rearward than the locking block portion  25   a  so as to extend in the extending direction of the first terminal  51 . The groove portion  25   e  is configured to extend to pass through the lance holding portion  14   b  opened to the rear end face  14   c  of the first body portion  14 . Therefore, when the first terminal  51  is inserted to be fitted into the first terminal cavity  14   a  from the rear side of the first body portion  14 , the locking piece  55   d  which is projected further upward than the top plate portion  55   a  of the first contacting distal end portion  55  passes through the groove portion  25   e , so that the first terminal  51  can be smoothly inserted into the first terminal receiving portion  14   a . When the first contacting distal end portion  55  is moved forward in the first terminal receiving portion  14   a  so that the locking piece  55   d  passes under the locking block portion  25   a , the locking piece  55   d  is elastically deformed so that the distal end  55   f  is deformed downward. When the locking piece  55   d  has completely passed through, the locking piece  55   d  elastically restores its original shape, so that the distal end  55   f  is deformed upward to be locked at the front end face  25   h  of the locking block portion  25   a . Due to such a configuration, the first terminal  51  which has been completely inserted into the first terminal cavity  14   a  will not be moved toward the rear side. Moreover, the operator is able to perceive the resistance received from the locking block portion  25   a  when the locking piece  55   d  is elastically deformed by sensing a clicking feeling. Accordingly, the operator is able to correctly become aware of and to confirm the completion of the operation of fitting the first terminals  51  into the first housing  11 . 
     Next, the detailed description of the configuration of the lance  25  will be provided below. The lance  25  has a base end thereof being connected to the lance holding portion  14   b  and is provided with the locking block portion  25   a  which is in mass form and is arranged at the front end thereof so as to extend forward from the lance holding portion  14   b . The groove portion  25   e  is formed on a portion of the lower surface of the lance  25  being located further rearward than the locking block portion  25   a , and the groove portion  25   e  extends to pass through the lance holding portion  14   b  opened to the rear end face  14   c  of the first body portion  14 . 
     Furthermore, on the front end face  25   h  of the locking block portion  25   a , a canopy portion  25   b  used as a projection portion configured to be projected forward from an upper end of the front end face  25   h  and laterally covering portions  25   c  as projection portions configured to be projected forward from both left and right ends of the front end face  25   h  are formed to be integral with the front end face  25   h . Moreover, a concave portion having the perimeter thereof being defined by the front end face  25   h , the canopy portion  25   b , and the laterally covering portions  25   c  of the locking block portion  25   a  functions as a locking piece-accommodation concave portion  25   d , and the front end  55   f  of the locking piece  55   d  is accommodated in the locking piece-accommodation concave portion  25   d , whereby the locking piece  55   d  is prevented from being removed from the front end face  25   h  of the locking block portion  25   a.    
     The portion of the lance  25  located further rearward than the locking block portion  25   a  has a lower surface thereof having the groove portion  25   e  formed therein, so that the lance  25  is provided with the side portions  25   f  on both left and right sides thereof and the ceiling portion  25   g  which are configured to define the circumferential surfaces of the groove portion  25   e  and has a channel shape having a cross-section in the form of substantially squared U-shape. Moreover, a sloped portion  25   i  is formed on portions of the groove portion  25   e  being connected to the locking block portion  25   a , and the lower surface of the ceiling portion  25   g  is configured to be smoothly connected to the lower surface of the locking block portion  25   a  via the lower surface of the sloped portion  25   i . Due to such a configuration, when the first terminal  51  is inserted into the first terminal cavity  14   a  from the rear of the first body portion  14 , the locking piece  55   d  can smoothly pass under the locking block portion  25   a . Since the lance  25  has such a shape, it is possible to prevent the occurrence of weld lines at the base end of the lance  25  or the vicinity thereof. 
     The first housing  11  is molded by integral molding with resin, and a gate portion which is an entrance port of molten resin in a resin-molding mold is generally positioned at a position corresponding to the vicinity of the center of the first body portion  14 . Therefore, the lance  25  is located at a distance from the gate portion and the end point of the flow of the molten resin. Therefore, weld lines, which are lines representing an interface which is formed because two converging flows of the molten resin are unable to reunite, are likely to occur in the lance  25 . 
     However, the lance  25  is provided with a groove portion  25   e  formed further rearwardly than the locking block portion  25   a  and this lance has a channel shape having a cross-section in the form of substantially squared U-shape, and an underpart thereof is bifurcated to the left and the right. Therefore, it is difficult for the flows of molten resin, which are caused to flow toward the lance  25  from the lance holding portion  14   b  of the first body portion  14 , to reunite from the left and the right. As a result, the weld lines, which are lines representing an interface which is formed because two converging flows of the molten resin are unable to reunite, will not occur at the base end of the lance  25  or the vicinity thereof, namely the portions thereof being connected to the lance holding portion  14   b  or the vicinity of the lance holding portion  14   b . The weld lines do not occur at the whole portion of the lance  25  on which the groove portion  25   e  is formed. 
     As illustrated in  FIGS. 8C to 8E , the cross-sectional area of the portion on which the groove portion  25   e  is formed is smaller than the cross-sectional area of the locking block portion  25   a  which is connected to the distal end of said portion. Therefore, since in the portion on which the groove portion  25   e  is formed, the molten resin flowing from the lance holding portion  14   b  can smoothly flow toward the distal end and the occurrence of the weld lines can be prevented more effectively.  FIG. 8E  is illustrating the cross section of the portion on which the sloped portion  25   i  is formed, and more strictly speaking, the approximate cross section of the locking block portion  25   a  rather than the cross section of the locking block portion  25   a  itself. 
     As illustrated in  FIGS. 8C and 8D , in the cross section of the portion on which the groove portion  25   e  is formed, the thickness dimension of the side portion  25   f , indicated by arrow □, is substantially equal to or larger than the thickness dimension of the ceiling portion  25   g , indicated by arrow. Namely, the portion of the lance  25  on which the groove portion  25   e  is formed has a substantially constant thickness. Therefore, the flow of the molten resin flowing from the lance holding portion  14   b  will not be biased, and the occurrence of the weld lines can be prevented more effectively. 
     The groove portion  25   e  is formed to extend to pass through not only the lance  25  but also the lance holding portion  14   b . Therefore, since the flow of the molten resin toward the lance  25  is bifurcated to the left and the right at the under part of the lance holding portion  14   b , the occurrence of the weld lines resulting from the converging flows from the left and the right can be suppressed more effectively. 
     Since the sloped portion  25   i  is formed, the cross-sectional area of the sloped portion  25   i  increases gradually from the portion on which the groove portion  25   e  is formed to the locking block portion  25   a . Therefore, since the flows of molten resin flowing toward the locking block portion  25   a  are able to reunite gradually, the occurrence of weld lines in the locking block portion  25   a  can be prevented effectively. 
     Since the canopy portion  25   b  and the laterally covering portions  25   c  are connected to the front end face  25   h  of the locking block portion  25   a , the molten resin flowing toward the locking block portion  25   a  is caused to flow toward the canopy portion  25   b  and the laterally covering portions  25   c . Therefore, the molten resin is able to flow smoothly, and the occurrence of the weld lines in the locking block portion  25   a  can be prevented more effectively. 
     As described above, since the lance  25  according to the present embodiment has such an appropriate shape, the occurrence of the weld lines in the lance  25  can be prevented effectively. Even when weld lines occur, they will occur in the locking block portion  25   a  which is the distal end of the lance  25  or the canopy portion  25   b  and the laterally covering portions  25   c  which are connected to the front end face  25   h  and will not occur at the base end of the lance  25  or the vicinity thereof. Therefore, even when a strong force is applied thereto from the first terminal  51  via the locking piece  55   d , it is not likely that there will be an unfavorable state such that the whole body of the lance  25  is broken so that the first terminal  51  fitted into the first housing  11  are removed toward the rear side. 
     Moreover, since the portion of the lance  25  on which the groove portion  25   e  is formed has a channel shape having a cross-section in the form of substantially squared U-shape, the portion has a large secondary section modulus thereof and a high rigidity. Therefore, the lance  25  will exhibit a sufficiently high rigidity even when the groove portion  25   e  is formed therein. Even when a strong force is applied thereto from the first terminal  51  via the locking piece  55   d , it is not likely that there will be an unfavorable state such that the whole body of the lance  25  is broken so that the first terminal  51  fitted into the first housing  11  are removed toward the rear side. 
     Next, the description of the structure of the second connector  101  will be provided herein below. The second connector  101  includes a second housing  111  as a female board housing which has a generally rectangular overall shape and is integrally formed of an insulating material such as synthetic resin, second terminals  151  as female board terminals which are made of metallic material and fitted in the second housing  111 , and second auxiliary metallic brackets  181  as female board housing-attachment auxiliary metallic brackets which are made of metallic material and attached to the second housing  111 . 
     As shown in the drawings, the second housing  111  is provided with a second bottom plate portion  118  as a bottom plate portion which has a generally rectangular flat-plate shape opposing the top surface of the board  191 , a second body portion  114  as a body portion which is formed so as to extend along an edge on the rear side (the left end in  FIGS. 10 and 11 ) of the second bottom plate portion  118  and upstand from the second bottom plate portion  118 , thereby holding therein the second terminals  151 , and a pair of second side wall portions  117 , as side wall portions, which is formed so as to extend along edges on both left and right sides of the second bottom plate portion  118  and upstand from the second bottom plate portion  118 . Moreover, a second fitting face  111   a  as a fitting face is configured to extend in a direction intersecting (preferably, in a direction substantially perpendicular to) the top surface of the board  191 . The rear ends of the second side wall portions  117  are connected to both left and right ends of the second body portion  114 , the upper surface portions of the second side wall portions  117  and the upper surface portion of the second body portion  114  are formed to be continuous and even with each other, thus constituting a second top plate portion  112  having a substantially squared U-shape. Moreover, a central concave portion designated by reference numeral  113  has a lower portion thereof being defined by the second bottom plate portion  118  and three sides thereof being defined by the second side wall portions  117  and the second body portion  114 . 
     The second body portion  114  has formed therein, on a rear end face thereof, second terminal accommodation-concave portions or cavities  114   a  which are configured to extend in the distal end direction (the rightward direction in  FIGS. 10 and 11 ) from the rear end face and accommodate therein the second terminals  151  and second terminal holding portions  114   b  which are arranged at positions of the second terminal CAVITIES  114   a  located between the second bottom plate portion  118  and the second top plate portion  112  so as to hold therein the second terminals  151 . 
     Each of the second side wall portions  117  has formed therein laterally convex portions  117   a  which are formed on side faces thereof so as to protrude laterally. Moreover, each of the second side wall portions  117  has formed therein rearwardly convex portions  117   d  which are formed on a rear face thereof so as to protrude rearward. Furthermore, each of the second side wall portions  117  has formed therein bracket holding grooves  117   b  which are formed in the vicinity of the lower end thereof so as to extend in the front-to-rear direction so that the second auxiliary metallic brackets  181  are accommodated in the bracket holding grooves  117   b . In addition, second connecting portions  183  as connecting portions, which are formed so as to laterally protrude from the lateral ends of the second auxiliary metallic brackets  181 , are fixedly secured, by soldering or the like, to second connector fixing portions  194  such as solder pads which are formed on the top surface of the board  191 . In this way, the second connector  101  can be firmly secured to the board  191 . As illustrated in  FIGS. 9 and 10 , it is preferable that the second auxiliary metallic brackets  181  and the second connecting portions  183  do not protrude rightward or leftward from the laterally convex portions  117   a  of the second side wall portions  117 . 
     A second engagement portion  115  is arranged within the central concave portion  113  so as to be engaged with the first connector  1 . The second engagement portion  115  is provided with a second engagement top plate portion  115   a  which is formed to be in parallel to the second top plate portion  112 , and a second engagement support wall portion  115   b  which extends in the front-to-rear direction and supports the second engagement top plate portions  115   a . The second engagement support wall portion  115   b  is formed so as to upstand from the second bottom plate portion  118  at the central portion in the width direction of the second bottom plate portion  118  and has its upper end to which the second engagement top plate portion  115   a  is connected. 
     The second engagement top plate portion  115   a  is arranged at a lower position than the second top plate portion  112  which surrounds the three sides thereof. When the first connector  1  and the second connector  101  are engaged together by fitting, the first engagement top plate portion  15   a  of the first engagement portion  15  is positioned so as to overlap the upper surface of the second engagement top plate portion  115   a  so that the upper surface of the first engagement top plate portion  15   a  becomes substantially even with the upper surface of the second top plate portion  112 . The upper surface of the second engagement top plate portion  115   a  is smooth and flat and may function as a suctioned surface which is absorbed and sucked by a suction tool arranged at the distal end of a tool such as a robot hand, during assembling steps for mounting the second connector  101  on the top surface of the board  191 . The absorption and suction by the suction tool is generally impossible when an uneven structure such as a scratch exists on the suction surface. However, since the upper surface of the second engagement top plate portion  115   a  in the present embodiment has its three sides thereof being surrounded by the second top plate portion  112  having a large height, the upper surface is hardly damaged by coming into contact with other members during operations such as assembly steps. Therefore, the upper surface of the second engagement top plate portion  115   a  is free of uneven structures and is thus able to reliably function as a suctioned surface. 
     Moreover, spaces between the second engagement top plate portion  115   a  and the second bottom plate portion  118  on both left and right sides of the second engagement support wall portion  115   b  are configured as second concave engagement portions  113   a  as concave portions which are engaged with the first connector  1 . The first terminal restricting portion  16  and the first contacting distal end portion  55  of the first terminal  51  are inserted into the second concave engagement portions  113   a . Furthermore, slit-like openings which are formed between both left and right edges of the second engagement top plate portion  115   a  and the second side wall portions  117  on the left and right sides so as to extend in the front-to-rear direction are configured as second lateral engagement concave portions  113   b  which are in communication with the second concave engagement portions  113   a . The first engagement side wall portions  15   b  of the first engagement portion  15  are inserted into the second lateral engagement concave portions  113   b . In addition, on the inner left and right side faces of the second side wall portions  117 , second engagement groove portions  117   c  are formed, which are trenches having a rectangular cross section; opened toward the second concave engagement portions  113   a , and extending in the front-to-rear direction. The first convex engagement portions  15   c  of the first engagement portion  15  are inserted into the second engagement groove portions  117   c.    
     The second terminals  151  according to the present embodiment are integrally formed in a bifurcated element by applying processing, e.g., punching, to a metallic plate and have a generally squared C-shaped or U-shaped side form as illustrated in  FIG. 12 . Each of the second terminals  151  is provided with a second fixing portion  153  as a body portion, a second tail portion  152  as a second surface connecting portion which extends rearward from the lower end of the second fixing portion  153 , and a second contacting arm portion  154  which extends frontward from the second fixing portion  153 . 
     In the second tail portion  152 , a portion thereof connected to the second fixing portion  153  is accommodated in the second terminal cavity  114   a , whereas the remaining portion thereof is exposed further rearward (Leftward, in  FIGS. 10 and 11 ) than the rear face of the second body portion  114  from the lower end of the second terminal cavity  114   a . The second tail portion  152  is electrically connected and secured, by soldering or the like, to a second connector electrode portion  193 , such as a conductive pad, formed on the top surface of the board  191 . Hence, the second terminals  151  are connected to non-illustrated conductive traces for power supply of the board  191 , formed to be connected to the second connector electrode portions  193 . Here, it is preferable that the second tail portion  152  does not protrude rearward from the rearwardly convex portion  117   d  of each of the second side wall portions  117  and does not protrude upward from the upper end of the rearwardly convex portion  117   d.    
     The second contacting arm portion  154  is provided with a second upper contacting arm portion  155  which extends frontward from the upper end of the second fixing portion  153  and a second lower contacting arm portion  156  which extends frontward from the lower end of the second fixing portion  153 . An upper contacting portion  155   a  configured to protrude downward is formed at the free end, namely in the vicinity of the distal end of the second upper contacting arm portion  155 , and a lower contacting portion  156   a  configured to protrude upward is formed at the free end, namely in the vicinity of the distal end of the second lower contacting arm portion  156 . The upper contacting portion  155   a  and the lower contacting portion  156   a  are portions which function as second contacting distal end portions of the second terminals  151  and come into electrical contact with the first contacting distal end portions  55  of the first terminals  51 . Since at least the second upper contacting arm portion  155  of the second contacting arm portion  154  has some degree of flexibility and is thus able to elastically deform in the vertical direction, at least the upper contacting portion  155   a  is able to elastically deform in the vertical direction to some extents. 
     A second locking projection  153   b  configured to project upward is formed in a connecting portion of the second fixing portion  153  and the second lower contacting arm portion  156 . When the second terminals  151  are press-fitted into the second terminal accommodation-concave portions  114   a , the second locking projections  153   b  are squeezed into the lower surfaces of the second terminal holding portions  114   b  so that they are locked. Moreover, the upper end portion  153   c  and the lower end portion  153   d  of the second fixing portion  153  are pressed against the lower surface of the second terminal holding portion  114   b  and the upper surface of the second bottom plate portion  118 , respectively. That is to say, the second terminals  151  are securely held in the second terminal accommodation-concave portions  114   a  when the second locking projections  153   b  are squeezed into the lower surfaces of the second terminal holding portions  114   b  and the second fixing portions  153  are pinched from the upper and lower sides by the second terminal holding portions  114   b  and the second bottom plate portion  118 . 
     For prevention of flux creep, a plurality of groove portions  153   a  is formed on the side faces of the second fixing portion  153 . When the second tail portion  152  is soldered to the second connector electrode portion  193  formed on the top surface of the board  191 , a flux creep phenomenon generally occurs in which flux contained in the solders generally melts down to creep up along the surface of the second terminal  151 . Since the flux has insulating properties, when the flux adheres on the surface of the second upper contacting arm portion  155  and the second lower contacting arm portion  156 , it is difficult to achieve an electrical connection with the first contacting distal end portions  55  of the first terminals  51 . In such a case, the flux creep mainly occurs in the side faces of the second terminals  151 . Therefore, in the present embodiment, the groove portions  153   a  are formed on the side faces of the second fixing portion  153 . The number, the width, the depth, the shape and the like of the groove portions  153   a  are appropriately determined in consideration of the strength or the like of the second fixing portion  153 . 
     The second connector  101  is mounted on the end of the board  191  as illustrated in  FIGS. 10 and 11 . Although only the portions disposed in the vicinity of the end of the board  191  are illustrated the board  191  may be an rectangular shape, for example, and is larger than the illustration, and the second connector  101  is mounted on one end of its both longitudinal ends. Specifically, as illustrated in  FIG. 11 , the second connector  101  is mounted at such a position that the second fitting face  111   a  protrudes outward from an end face  191   a  of the board  191  and that the front end of the second bottom plate portion  118  of the second housing  111  becomes substantially identical with the end face  191   a  which is one of both longitudinal ends of the board  191 . It should be noted that the front end of the second bottom plate portion  118  is not necessary perfectly even with the end face  191   a  of the board  191 ; however, it is preferable that the distance between the front end of the second bottom plate portion  118  and the end face  191   a  of the board  191  is short, as illustrated in  FIG. 11 . 
     The front end of the second bottom plate portion  118  is connected to a second projecting plate portion  121  as a projecting plate portion which is configured to extend frontward. The second projecting plate portion  121  is formed to extend in the distal end direction from the front end of the second bottom plate portion  118  so as to protrude frontward from the front end of the second engagement portion  115  as illustrated in  FIG. 9B . 
     When a conductive member such as a conductive casing, a conductive plate for electromagnetic shielding or the like is arranged on the rear side of the board  191 , the second projecting plate portion  121  functions as an insulating distance-procuring portion. Since the conductive member functions as the ground at zero electric potential, potential difference may occur between the second terminal  151  and the conductive member. If the second projecting plate portion  121  is omitted, the insulating distance between a portion of the conductive member arranged on the rear side of the board  191 , and located closer to the front side than the end face  191   a  and the distal end of the second lower contacting arm portion  156  will be shortened. However, in the present embodiment, since the second projecting plate portion  121  protrudes frontward from the distal end of the second lower contacting arm portion  156  in the lower portion of the second lower contacting arm portion  156 , both the clearance and the creepage distance between the conductive member and the distal end of the second lower contacting arm portion  156  can be sufficiently lengthened, and thus, a sufficient insulating distance can be procured. Moreover, when the first connector  1  and the second connector  101  are engaged together by fitting, since a portion of the first contacting distal end portions  55  of each of the first terminals  51  will also have its lower portion covered by the second projecting plate portion  121 , the insulating distance between the conductive member and the first contacting arm portion  54  of each of the first terminals  51  can be secured by the second projecting plate portion  121 . 
     Next, the description of an operation of fitting the first connector  1  and the second connector  101  having the above-described structures to be engaged together will be provided. Here, the first connector  1  is connected to the termination ends of the electrical wires  91  of the first terminals  51  to be connected to the termination end of the cable having the wires  91 . The second connector  101  is surface-mounted on the board  191  in a state where the second tail portions  152  of the second terminals  151  are connected, by soldering or the like, to the second connector electrode portions  193  formed on the top surface of the board  191 , and that the second connecting portions  183  of the second auxiliary metallic brackets  181  are connected, by soldering or the like, to the second connector fixing portions  194  formed on the top surface of the board  191 . 
     Then, an operator moves the first connector  1  and/or the second connector  101  toward either one of the connectors in a state where the first fitting face  11   a  of the first connector  1  opposes the second fitting face  111   a  of the second connector  101  so that the first terminal restricting portions  16  and the first contacting distal end portions  55  of the first terminals  51  of the first connector  1  are inserted into the second concave engagement portions  113   a  of the second connector  101 . Moreover, the first engagement side wall portions  15   b  of the first engagement portion  15  of the first connector  1  are inserted into the second lateral engagement concave portions  113   b  of the second connector  101 . Furthermore, the first convex engagement portions  15   c  of the first engagement portion  15  of the first connector  1  are inserted into the second engagement groove portions  117   c  of the second connector  101 . In this way, the first connector  1  and the second connector  101  are engaged together as illustrated in  FIGS. 13 to 15 . 
     At this time, as illustrated in  FIG. 15 , the first contacting distal end portions  55  of the first terminals  51  of the first connector  1  come to be positioned between the upper contacting portions  155   a  and the lower contacting portions  156   a  of the second terminals  151  of the second connector  101 . Moreover, the upper contacting portions  155   a  and the lower contacting portions  156   a  of the second terminals  151  come into contact with the top plate portion  55   a  and the bottom plate portion  55   b  of the first contacting distal end portions  55 . In this way, the first terminals  51  and the second terminals  151  are electrically connected to each other. As a result, the electrical wire  91  connected to the first terminals  51  are electrically connected to the conductive traces connected to the second connector electrode portions  193  on the board  191  being connected to the second tail portions  152  of the second terminals  151 . 
     When the first contacting distal end portions  55  of the first terminals  51  come to be positioned between the upper contacting portions  155   a  and the lower contacting portions  156   a  of the second terminals  151 , the distance between the upper contacting portions  155   a  and the lower contacting portions  156   a  is increased. In this case, the second upper contacting arm portions  155  are elastically deformed vertically, so that the upper contacting portions  155   a  are elastically displaced upwardly, thereby increasing the distance between the upper contacting portions  155   a  and the lower contacting portion  156   a . Therefore, the operator is able to perceive, by a sense of click-feeling, the resistance that the first contacting distal end portions  55  of the first terminals  51  receive when the upper contacting portions  155   a  are elastically displaced upwardly. Accordingly, the operator is able to correctly become aware of and to confirm completion of the operation of electrically connecting the first terminals  51  and the second terminals  151  so that the first connector  1  and the second connector  101  are engaged together. Moreover, since the first contacting distal end portions  55  of the first terminals  51  are elastically grasped from the upper and lower sides by the upper contacting portions  155   a  and the lower contacting portions  156   a  of the second terminals  151 , it is possible to certainly maintain stable contact between the first contacting distal end portions  55  and the upper contacting portions  155   a  and the lower contacting portions  156   a.    
     When the engagement between the first connector  1  and the second connector  101  is completed, as illustrated in  FIG. 15 , the second projecting plate portion  121  of the second housing  111  covers the entire lower surface of the first projecting plate portion  22  of the first housing  11 . Therefore, a portion disposed right above the end face  191   a  of the board  191  is covered by the first projecting plate portion  22  and the second projecting plate portion  121  which overlap with each other. 
     As described above, when a conductive member such as a conductive casing, a conductive plate for electromagnetic shielding, a metal plate for fixation, radiation, or reinforcement, another printed circuit board, another wiring component, or a fixing bracket is arranged on the rear side of the board  191 , since the conductive member functions as the ground at zero electric potential, if the first projecting plate portion  22  and the second projecting plate portion  121  do not appear, the insulating distance between the conductive member disposed under the end face  191   a  of the board  191  and the first terminals  51  and/or the second terminals  151  will be shortened. As will be easily understood from  FIG. 15 , particularly, the insulating distance between the conductive member and the bottom plate portions  55   b  of the first contacting distal end portions  55  of the first terminals  51  and/or the distal ends of the second lower contacting arm portions  156  of the second terminals  151  will also be shortened. 
     However, in the present embodiment, the first projecting plate portion  22  and the second projecting plate portion  121  which overlap with each other cover the portion disposed right above the end face  191   a  of the board  191 . Therefore, both the spatial distance and the creepage distance between the conductive member and the bottom plate portions  55   b  of the first contacting distal end portions  55  of the first terminals  51  and/or the distal ends of the second lower contacting arm portions  156  of the second terminals  151  can be sufficiently lengthened, and thus, a sufficient insulating distance can be procured. 
     For example, as will be obvious from the example illustrated in  FIG. 15 , the above-mentioned creepage distance can be sufficiently long by virtue of the fact that it is approximately identical to the total sum of the distances of paths: including a path extending from the lower end to the upper end of the board  91  along its end face  191   a ; a path extending from the base end to the distal end of the second projecting plate portion  121  along its lower surface; and a path extending from the base end to the distal end of the first projecting plate portion  22  along its lower surface (or a path extending from the distal end to the base end of the second projecting plate portion  121  along its upper surface). 
     Therefore, it is possible to certainly prevent occurrence of any short-circuit accidents between the conductive member and the first terminals  51  and/or the second terminals  151 . In the example illustrated in the drawing figures, only the first contacting distal end portion  55  of each of the first terminals  51  are positioned right above the end face  191   a  of the board  191 . However, the second upper contacting arm portion  155  or the second lower contacting arm portion  156  of each of the second terminals  151  may be positioned right above the end face  191   a  of the board  191 . Moreover, either one of the first projecting plate portion  22  or the second projecting plate portion  121  may be omitted as required. 
     When the engagement between the first connector  1  and the second connector  101  is completed, the first engagement side wall portions  15   b  of the first engagement portion  15  of the first housing  11  come into the second lateral engagement concave portions  113   b  of the second housing  111 . Moreover, the first convex engagement portions  15   c  of the first engagement portion  15  of the first housing  11  come into the second engagement groove portions  117   c  of the second housing  111 , and the first engagement top plate portion  15   a  of the first engagement portion  15  of the first housing  11  comes into the central concave portion  113  of the second housing  111 . Furthermore, the first engagement top plate portion  15   a  overlaps the upper surface of the second engagement top plate portion  115   a  of the second housing  111 . 
     The concave engagement portions  17   c  of the first connector  1  which are formed on the inner side faces of the front end portion of the locking arm portion  17   b  are engaged with the laterally convex portions  117   a  of the second connector  101  which are formed on the side faces of the second side wall portions  117 , whereby the first connector  1  and the second connector  101  are locked. 
     Due to the described configuration, the first housing  11  and the second housing  111  can be firmly engaged together, and accordingly, the engagement between the first connector  1  and the second connector  101  is not released even when the relative positional relationship between the first connector  1  and the second connector  101  changes. Moreover, even when the electrical wires  91  are pulled or the electrical wires  91  are subjected to a shaking motion, the engagement between the first connector  1  and the second connector  101  will not be released. 
     Furthermore, since the distal end  55   f  of the locking piece  55   d  of the first terminal  51  is locked at the front end face  25   h  of the lance  25 , the first terminal  51  fitted into the first housing  11  will not be removed toward the rear side even when the electrical wire  91  is subjected to a shaking or flapping motion. 
     As described above, in the present embodiment, the wire-to-board connector includes the first connector  1  having the first housing  11  made of an insulating material and the first terminal  51  connected to the termination end of the electrical wire  91  to be fitted in the first housing  11 , the first connector  1  having the first fitting face  11   a  extended in a direction (preferably, in a direction substantially perpendicular to and) intersecting the extending direction of the first terminal  51 ; and the second connector  101  having the second housing  111  made of an insulating material and the second terminal  151  fitted in the second housing  111  and configured to make contact with the first terminal  51 , the second connector  101  being configured to be surface-mounted on the top surface of the board  191  to be engaged with the first connector  1  and having the second fitting face  111   a  extended in a direction (preferably, in a direction substantially perpendicular to and) intersecting the top surface of the board  191 . The first housing  11  is provided with the first terminal accommodation-concave portion  14   a  which is configured to be opened to the rear end face  14   c  opposing the first fitting face  11   a  and the lance  25  which is arranged in the first terminal accommodation-concave portion  14   a  and is formed therein with the groove portion  25   e  extended in the extending direction of the first terminal  51 . The first terminal  51  is provided with the first contacting distal end portion  55  configured to make contact with the second terminal  151  and the locking piece  55   d  which is formed on the first contacting front end portion  55  and configured to be locked at the front end face  25   h  of the lance  25 , where the first terminal  51  is inserted to be fitted into the first terminal accommodation-concave portion  14   a  from the side of the rear end face  14   c.    
     Due to such a configuration, it is possible to prevent the occurrence of weld lines at the base end of the lance  25  or the vicinity thereof. As a result, it is made possible to stably hold the first terminal  51  to be firmly secured to the first housing  11  while reliably preventing the removal of the first terminal  51 , thereby realizing a simple structure, a low height, and miniaturization of a wire-to-board connector and a wire connector. Accordingly, it is possible to provide a wire-to-board connector and a wire connector which can be easily produced to have a simple structure with a small number of parts and low production costs. 
     Moreover, the lance  25  has the base end thereof which is connected to the first body portion  14  of the first housing  11  and extended in the direction of the first fitting face  11   a , and has the front end thereof having the locking block portion  25   a  formed thereon, the groove portion  25   e  being formed on a surface of the lance  25  located further rearward than the locking block portion  25   a , where the lance  25  has a channel shape having a cross-section in the form of substantially squared U-shape. Due to such a configuration, weld lines will not occur in the portion of the lance  25  on which the groove portion  25   e  is formed, and the lance  25  has a large secondary section modulus and a high rigidity, and will not be broken. 
     Furthermore, the groove portion  25   e  is configured to be extended to pass through the first body portion  14  to be opened to the rear end face  14   c . Due to such a configuration, the occurrence of weld lines can be prevented more effectively. 
     Furthermore, the lance  25  is provided with the ceiling portion  25   g  and side portions  25   f  on both left and right sides thereof, the ceiling portion  25   g  and the side portions  25   f  being configured to define the circumferential surfaces of the groove portion  25   e , the thickness dimension of each of the side portions  25   f  being designed to be equal to or larger than the thickness dimension of the ceiling portion  25   g . Due to such a configuration, the occurrence of weld lines can be prevented more effectively. 
     Furthermore, the sloped portion  25   i  is formed on portions of the groove portion  25   e  being connected to the locking block portion  25   a  so that the cross-sectional area of the sloped portion  25   i  increases gradually from the groove portion  25   e  to the locking block portion  25   a . Due to such a configuration, the occurrence of weld lines in the locking block portion  25   a  can be prevented effectively. 
     Moreover, the first housing  11  is provided with the first bottom plate portion  18  configured to be extended in the extending direction of the first terminals  51 , the second housing  111  is provided with the second bottom plate portion  118  configured to oppose the top surface of the board  191 , and the projecting plate portion, which is configured to procure the insulating distance between the first terminals  51  or the second terminals  151 , is extended from the front end of the first bottom plate portion  18  or the second bottom plate portion  118 . Due to such a configuration, since the under parts of the first terminals  51  or the second terminals  151  are covered by the projecting plate portion, it is possible to procure a sufficient insulating distance between the conductive member and the first terminals  51  or the second terminals  151 . 
     Furthermore, when the first connector  1  and the second connector  101  are engaged together, a portion of each of the first terminals  51  or the second terminals  151  is positioned right above the portion which is disposed between the front end of the first bottom plate portion  18  and the front end of the second bottom plate portion  118 , and the projecting plate portion covers the lower portion of the portion of each of the first terminals  51  or the second terminals  151  disposed right above the portion between the front end of the first bottom plate portion  18  and the front end of the second bottom plate portion  118 . Due to such a configuration, even when a conductive member is present between the front end of the first bottom plate portion  18  and the front end of the second bottom plate portion  118 , it is possible to secure a sufficient insulating distance between the conductive member and the first terminals  51  or the second terminals  151 . 
     While a preferred embodiment of the Present Disclosure is shown and described, it is envisioned that those skilled in the art may devise various modifications without departing from the spirit and scope of the foregoing Description and the appended Claims.