Patent Publication Number: US-7220146-B2

Title: Miniaturization facilitating plug connectors

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a connector for a plurality of cables. The connector provides electrical connection between the cables and a circuit board in a manner that fosters miniaturization and avoids undue stiffness of the cables at the connector. 
   Coaxial cables are known as cables for transmitting high-frequency signals in portable telephones, personal computers, and the like in order to transmit a volume of information. As shown in prior art  FIGS. 37 and 38 , a typical coaxial cable  300  is composed of a signal line  306  having a centrally located inner conductor  302  covered with an inner insulator  304 , an outer conductor  308  consisting of a large number of spirally wound or braided electric wires and covering the signal line  306 , and an outer insulator  310  covering the outer conductor  308 . 
   Soldering methods are among the technologies available to connect a cable such as the coaxial cable  300  to a connector. As shown in  FIG. 39 , a known soldering method exposes the outer conductor  308  and the inner conductor  302  by stripping off the outer insulator  310  and the inner insulator  304 , and the outer conductor  308  is twisted into a strand and then soldered between flat metal sheets (not shown). In this known soldering method, when soldering the coaxial cables to terminals, the solder can be “sucked up” by the outer conductor  308  through a phenomenon known as “solder wicking”. In such a case, the outer conductor  308  becomes hard. Once the outer conductor  308  becomes hard, the coaxial cables are not flexible, and they thereby become difficult to wind or twist and/or difficult to arrange in a narrow space such as inside a portable telephone. Such difficulties make the coaxial cables inconvenient and inefficient and at times unsuitable for applications where increased miniaturization is an objective. Further, if extraordinary outer forces are imparted to the hardened portion, cracking of the hardened portion may be experienced. 
   As the types of connectors have diversified in recent years, connectors having a large number of terminals arranged in parallel have come into use. With such connectors, their large number of parallel terminals are connected to flat cables having a large number of coaxial cables. Connectors having such flat cables can be components of many devices or electronic instruments. For instance, in folding-type portable telephones, these types of connectors are used for transmitting signals between a liquid crystal screen and operational buttons on opposite sides of the device joined through a hinge. The portable telephone is folded by rotating one side to the other side but the cables typically are arranged in the hinge portion. When the hardening phenomenon due to soldering occurs at such hinge portion cable areas, a device such as a portable telephone becomes difficult to fold, the connector is not easily passed through a cable insertion-hole (not shown) at the hinge, and/or connection failure may be induced. 
   Meanwhile, the need for miniaturization of portable instruments has been increasing over the years, which means that the outer dimensions of connectors cannot be increased. Hence, problems such as those noted herein must be addressed without increasing the size of the device, and prior approaches have focused on improvements in connector components. Prior publications along these lines teach technologies for effecting solder connection between a connector and a coaxial cable or other such electric wire. These include Japanese Patent Publication No. JP 2000-260497 A, No. JP 11-260439 A and No. JP 11-260440 A. 
   SUMMARY OF THE INVENTION  
   Problems such as those noted above are addressed with advantageous results by the present invention, which has been made in view of the above circumstances. In this regard, it is an object of the present invention to provide a technique with which, in mounting coaxial cables to a connector, solder wicking to the coaxial cables is prevented thereby avoiding undesirable hardening of wires which are components of the coaxial cables, which is especially important for connectors that are ever increasingly miniaturized. 
   To attain the above object, the present invention adopts the following approach. A connector is provided to which a plurality of cables each having a conductor covered with an insulator are attached. The connector has a housing serving as the base of the connector, a terminal held in the housing and connected with the conductor of the cables, and cable holders are provided in the housing for holding at least a portion of the respective distal end portions of the coaxial cables and a shell fitted in the housing to cover terminals and other parts. The cable holders hold the cable between the housing, and the housing includes fitting holes for receiving the cable holders, the shell including through holes provided in a position opposed to the fitting holes when positioning the shell in the housing. The cable holders have a double-legged portion consisting of a pair of legs for pinching the cables and a backbone portion for connecting the legs, the cable holders holding the cables with the double-legged portion and the backbone portion by straddling and pinching each cable, and the backbone portion is thereby positioned within the through holes. 
   The connector of the present invention is provided with the fitting holes in the housing for fitting the cable holders and the through holes in the shell coaxial to the fitting holes. When the cable holders are fitted into the fitting holes via the through holes, the cable holders straddle and pinch the cables between the housing and the cable holders in a secure manner. Since the cable holders are contained in the housing, the cables are held in the housing without requiring any soldering thereof. 
   When the cable holders are fitted into the fitting holes via the through holes, the backbone portions of the respective cable holders are positioned in the through holes. Comparing this configuration with the prior approach where the cable holders are fitted into the fitting holes in the housing and then the housing is covered with the shell, where both the present invention and the prior approach are same in the length of the cable holders and in the amount of insertion to the fitting holes in the housing, the cable holders of the present invention can reduce the height of the connector by an amount of the backbone portion facing to the through holes in the shell. 
   According to an overall aspect or object of the present invention, the wires of an electrical connector can be prevented from hardening and the connector can be miniaturized. The invention finds special applications in plug connectors for miniaturized electronic equipment. 
   Other aspects, objects and advantages of the present invention will be understood from the following description according to the preferred embodiments of the present invention, specifically including stated and unstated combinations of the various features which are described herein, relevant information concerning which is shown in the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view showing, together with a mating connector, a connector according to the present invention in a state prior to its mounting to the mating connector. 
       FIG. 2  is a perspective view showing the connector of the present invention as mounted to the mating connector, and an enlarged view of the essential portion thereof. 
       FIG. 3  is a perspective view showing the connector according to the present invention as applied to a foldable portable telephone. 
       FIG. 4  is an exploded perspective view of the connector according to the present invention. 
       FIG. 5  is a cross-sectional view through  FIG. 1 . 
       FIG. 6  is a cross-sectional view through  FIG. 2 . 
       FIG. 7  is a partially cut away side view and a partially cut away plan view of the connector according to the present invention, such being collectively shown, in which part (a) is the partially cut away plan view, and part (b) is the partially cut away side view. 
       FIG. 8  is an enlarged sectional view taken along the line A-A of  FIG. 7 . 
       FIG. 9  is an enlarged sectional view taken along the line B-B of  FIG. 7 . 
       FIG. 10  is an enlarged sectional view taken along the line C-C of  FIG. 7 . 
       FIG. 11  is a perspective view of a cable holder. 
       FIG. 12  is a front view and a side view of the cable holder, such being collectively shown, in which part (a) is the front view and part (b) is the side view. 
       FIG. 13  is a perspective view of a terminal as seen from one direction. 
       FIG. 14  is a perspective view of the terminal as seen from another direction from that of  FIG. 13 . 
       FIG. 15  is an enlarged plan view of a selected portion including a portion of a housing which includes the terminal. 
       FIG. 16  is a cross-sectional view of a selected portion of  FIG. 15 . 
       FIG. 17  is an enlarged plan view of a selected portion illustrating the case where an inner conductor of a coaxial cable is placed in the terminal of  FIG. 14 . 
       FIG. 18  is a perspective view showing a first step of an illustrated soldering procedure for soldering the terminal and the coaxial cable together. 
       FIG. 19  is a perspective view showing a second step of the illustrated soldering procedure for soldering the terminal and the coaxial cable together. 
       FIG. 20  is a perspective view showing a third step of the illustrated soldering procedure for soldering the terminal and the coaxial cable together. 
       FIG. 21  is a longitudinal sectional view of a selected portion and a transverse sectional view of a selected portion  FIG. 18  shown together, in which part (a) is the longitudinal sectional view and part (b) is the transverse sectional view. 
       FIG. 22  is a longitudinal sectional view of a selected portion and a transverse sectional view of a selected portion of  FIG. 19  shown together, in which part (a) is the longitudinal sectional view and part (b) is the transverse sectional view. 
       FIG. 23  is a sectional view of a selected portion and a transverse sectional view of a selected portion of  FIG. 20  shown together, in which part (a) is the longitudinal sectional view and part (b) is the transverse sectional view. 
       FIG. 24  is a perspective view of the housing, and an enlarged view of the of the essential portion thereof. 
       FIG. 25  is a perspective view showing a state in which the terminal is attached to the housing of  FIG. 24 , and an enlarged view of the essential portion thereof. 
       FIG. 26  is a perspective view showing a state in which a ground bar is attached to the housing of  FIG. 24 , and an enlarged view of the essential portion thereof. 
       FIG. 27  is a perspective view showing a state in which the coaxial cable is attached to the housing of  FIG. 26 , and an enlarged view of the essential portion thereof. 
       FIG. 28  is a perspective view showing a state in which a shell is attached to the housing of  FIG. 27 , and an enlarged main portion view of the essential portion thereof. 
       FIG. 29  is a perspective view showing a state immediately prior to mounting to the housing of  FIG. 28  a cable holder for holding an odd-numbered coaxial cable as counted from the left side of the drawing, and an enlarged view of a selected portion thereof. 
       FIG. 30  is a perspective view showing a state immediately after mounting the cable holder of  FIG. 29  to the housing, and an enlarged view of a selected portion thereof. 
       FIG. 31  is a perspective view showing a state immediately prior to mounting to the housing of  FIG. 30  a cable holder for holding an even-numbered coaxial cable as counted from the left side of the drawing, and an enlarged view of a selected portion thereof. 
       FIG. 32  is a perspective view showing a state immediately after mounting the cable holder of  FIG. 31  to the housing, and an enlarged view of a selected portion thereof. 
       FIG. 33  is an enlarged vertical sectional view showing a state immediately prior to mounting to the housing of the cable holder for holding the odd-numbered coaxial cable as counted from the left side of the drawing. 
       FIG. 34  is a diagram continuous from  FIG. 33 , showing a state immediately after mounting the cable holder to the housing. 
       FIG. 35  is a diagram showing the terminal according to the present invention as compared with a conventional terminal having no depression and stepped portion, in which part (a) shows the terminal according to the present invention, and part (b) shows the conventional terminal. 
       FIG. 36  is a diagram for explaining the effect of forming a through-hole in the shell of the connector according to the present invention as compared with the case where no such through-hole is provided, in which part (a) shows the shell according to the present invention, and part (b) shows a shell with no through-hole. 
       FIG. 37  is a perspective view of a coaxial cable. 
       FIG. 38  is an enlarged transverse cross-sectional view of the coaxial cable shown in  FIG. 37 . 
       FIG. 39  is a diagram illustrating a state in which the coaxial cable of  FIG. 37  is soldered onto a terminal. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriate manner. 
     FIG. 1  is a perspective view illustrating, together with a mating connector  2 , a connector  1  according to the present invention in a state prior to its mounting to the mating connector  2 . The illustrated connector is a plug connector. Further,  FIG. 2  is a perspective view of the connector  1  as mated with the mating connector  2 . It is to be noted that, although not shown in  FIG. 2 , the connector  1  is also attached to the other end portion of a coaxial cable  300  for mounting to the mating connector  2 .  FIG. 3  illustrates an example where the connectors  1 ,  2  are applied to a foldable portable telephone  3  indicated by imaginary lines. 
   Connector  1  receives one end of the coaxial cable  300  and is connected to the mating connector  2  provided in a substrate (not shown) on a liquid crystal screen side  3   a  of the illustrated portable telephone  3 , and another connector  1  (not shown) is provided at the other end of the coaxial cable  300  and is connected to another mating connector  2  provided in a substrate on an operation button side  3   b  of the portable telephone  3 . Accordingly, signals are transmitted between the liquid crystal screen side  3   a  and the operation button side  3   b  of the portable telephone  3 , through the coaxial cable  300  having the connector  1  and the mating connector  2  provided at its opposite ends, from the operation button side  3   b  toward the liquid crystal screen side  3   a.    
   As can been seen from  FIG. 1  and  FIGS. 4 through 7 , the illustrated connector  1  has a housing  7  serving as the base of the connector  1 . A shell  9  is fitted on the housing  7  to cover terminals and other parts contained in the housing  7 . 
   Further, a large number of coaxial cables  300  described above are attached between the shell  9  and the housing  7  while arranged in parallel into a flat configuration and having their respective distal end portions  300   a  ( FIGS. 5 &amp; 6 ) sandwiched therebetween ( FIGS. 4-6 ). 
   The housing  7  is made of a synthetic resin or other insulating resin. As can be seen in  FIG. 4 , the housing  7  has the shape of an elongated quadrangle in a plan view and disposed in a direction orthogonal to the extending direction of the coaxial cables  300 . Further, the housing  7  has a cable holding portion  11  for holding the distal end portion  300   a  of the coaxial cables  300  (hereinafter referred to as the “cable distal end portion  300   a ”), a terminal insertion portion  13  which constitutes the connecting portion with the mating connector  2  and to which the same number of terminals  17  as that of the coaxial cables  300  are inserted, and an intermediate portion  15  located intermediate the cable holding portion  11  and the terminal insertion portion  13 . Due to the three portions described above, with the connector  1  attached to the mating connector  2 , the housing  7  has, as seen in cross-section, a substantially rectangular shape having a downwardly-opening depression at its central portion. ( FIG. 5 .) 
   Note that, as used herein, the words “upper (top)” and “lower (bottom)” refer to the upper (top) side and the lower (bottom) side as viewed facing the drawings, and the words “front” and “rear” refer respectively, to the side on which the terminal insertion portion  13  is provided as the front and the side on which the cable holder portion  11  is provided as the rear, in the extending direction of the coaxial cable  300  as attached to the connector  1 . Further, the words “left” and “right” as used herein refer to the left and right sides as viewed facing the extending direction of the coaxial cable  300 . Note that the left-to-right direction is herein referred to as the width direction. 
   The cable holding portion  11  has a plurality of pairs of cable holders  16 A,  16 B each made of conductive metal and holding an outer conductor  308  of each of the plurality of coaxial cables  300  while traversing the same ( FIGS. 4-10 ), and one ground bar  19  made of conductive metal like the cable holders  16 A,  16 B. By this arrangement, the conductor  308  is brought into electrical connection with the ground bar  19  and the plurality of pairs of cable holders  16 A,  16 B. 
   The cable holders  16 A and  16 B are identical in configuration and differ only in their mounting positions in the cable holding portion  11 . Accordingly, only one of the cable holders, namely the cable holder  16 A, is described below. As shown in  FIGS. 11 &amp; 12 , the cable holder  16 A has a substrate portion or backbone  16   a  extending in the left-to-right direction, and a large number of cantilever-like legs or tines  16   b  that are fixed at one end and free at the other end and extend downwardly in parallel from the substrate portion or backbone  16   a . The legs or tines are arranged in pairs of two each, forming downwardly-opening and reverse-U-shaped multiple grooves  16   c  of the same number as that of the coaxial cables  300 . A width W 1  ( FIGS. 12 &amp; 33 ) between adjacent legs or tines  16   b  forming each groove  16   c  is set to be substantially the same as a width W 2  ( FIG. 33 ) of each of cable holder fitting holes  111 A and  111 B which are provided in the housing  7  and in which the cable holders  16 A,  16 B are fitted. 
   The difference between the cable holders  16 A and  16 B is that the cable holder  16 A serves to hold the odd-numbered coaxial cables  300 A, and the cable holder  16 B serves to hold the even-numbered coaxial cables  300 B, as counted according to the plurality of coaxial cables  300  arranged in parallel from the end (the left side in  FIG. 4 ) of the coaxial cables  300  (FIGS.  4  &amp;  8 - 10 ). Further, the cable holders  16 A and  16 B are respectively associated with a large number of the cable holder fitting holes  111  A and  111 B provided in the cable holding portion  11  (see  FIGS. 4 ,  8 ,  9 ). Of the cable holders  16 A and  16 B, respective sets of a pair of adjacent legs or tines  16   b ,  16   b  are inserted into the cable holder fitting holes  111 A and  111 B. 
   These sets of the pairs of legs or tines  16   b ,  16   b  are simultaneously inserted into the multiple cable holder fitting holes  111 A and  111 B. Note that each set of the pair of legs or tines  16   b ,  16   b  is referred to as the double-legged or double-tined portion. The total number of each of the cable holder fitting holes  111 A and  111 B is the same as that of the coaxial cables  300 . As seen in vertical section with respect to the front-to-rear direction, the cable holder fitting holes  111 A and  111 B are each shaped like an inverted truncated isosceles triangle and tapered such that its opening is large at the top and small at the bottom. ( FIGS. 8 ,  9 ,  33  &amp;  34 .) A partition wall  113  is provided between adjacent cable holder fitting holes  111 A and between adjacent cable holder fitting holes  111 B. ( FIG. 4 .) 
   The cable holders  16 A and  16 B are engaged with the cable holder fitting holes  111 A,  111 B, respectively, in order to hold the coaxial cables  300  in a state of being in contact with the outer conductor  308  of each coaxial cable  300 , by the double-legged or double-tined portion and the substrate portion or backbone  16   a  in order to straddle and nip or pinch the coaxial cables  300  (see  FIGS. 5 and 6 ), thereby securely holding them in place. The cable holders  16 A,  16 B are arranged such that they are parallel to each other in the front-to-rear direction but are offset from each other in the left-to-right direction ( FIGS. 4 ,  8  &amp;  9 ). To realize this arrangement, a large number of cable holder fitting holes  111 A and  111 B, into which the cable holders  16 A,  16 B are respectively inserted, are formed linearly and equidistant from each other along the rear edge of the housing  7  such that they are parallel to each other in the front-to-rear direction but offset from each other in the left-to-right direction. ( FIGS. 4 ,  8 ,  9 ,  24  &amp;  25 .) 
   By inserting the cable holders  16 A,  16 B into the cable holder fitting holes  111 A,  111 B, respectively, the outer conductor  308  of each coaxial cable  300  is sandwiched from above and below by, and electrically connected with the ground bar  19  and the cable holders  16 A,  16 B. ( FIGS. 5 ,  6 ,  8 ,  10 ,  33  &amp;  34 .) The ground bar  19  is mounted so as to hold the cable holding portion  11  from the rear side of the cable holding portion  11  from three directions, that is, from above, below, and the rear (see  FIG. 4 ). Accordingly, the ground bar  19  has a hollow square pole-like configuration that is preferably open at its front and right and left sides, such that it has the shape of a horizontally channel when seen in cross section. Further, through-holes  191 A and  191 B, which are opposed to the cable holder fitting holes  111 A and  111 B, respectively, are formed in the upper surface of the ground bar  19  in the same number as that of the cable holder fitting holes  111 A and  111 B. ( FIGS. 4 ,  6  &amp;  26 .) 
   It will be appreciated that a large number of through holes  191 A and  191 B are formed linearly and at equal intervals from each other such that they are parallel in the front-to-rear direction, but offset in the left-to-right direction, from each other. Accordingly, upon mounting the ground bar  19  from the rear of the cable holding portion  11 , the cable holder fitting hole  111 A and the cable holder fitting hole  111 B are located coaxially in the top-to-bottom direction with respect to the through hole  191 A and the through-hole  191 B, respectively. ( FIGS. 8 &amp; 9 .) 
   The terminal insertion portion  13  of the housing  7  is provided with insertion holes  131  into which the terminals  17  are press fitted from above. ( FIGS. 4-6 .) Each insertion hole  131  is an elongated hole extending in the front-to-rear direction. Provided inside the insertion hole  131  ( FIGS. 5 &amp; 6 .) is a terminal holding portion, or male mating or plug portion,  133  for holding the terminal  17  fitted thereon. The terminal, which is connected to an inner conductor  302  of the coaxial cable  300  by soldering, is formed by machining a thin metal plate. Further, as shown in  FIGS. 4 ,  5 ,  6 ,  13 ,  14 ,  18 ,  19 ,  20  &amp;  35 , the terminal is sized and shaped to be inserted in the terminal insertion portion  13 . The terminal has a body portion that has a termination surface and at least one contacting portion extending therefrom. The illustrated terminal  17  has multiple contacting portions including a front upright leg  171   f  and a rear upright leg  171   r , which are spaced from each other in the front-to-back direction. A body or connecting portion  172  is provided on top of those legs and connects the two legs  171   f ,  171   r  at their respective one ends, thus defining a substantially gate-like double-legged configuration in this illustrated embodiment. 
   Formed on the inner side of the rear upright leg  171   r  is a locking member  173  for preventing dislodging of the terminal  17  inserted in the insertion hole  131  (see  FIGS. 13 and 14 ). The terminal  17  is received into the insertion hole  131  of the terminal insertion portion  13  from the distal end of the terminal  17 , the distal end being the free end side of the respective upright legs  171   f ,  171   r . When the terminal  17  is inserted into the insertion hole  131 , the locking member  173  bites into the male mating, plug or terminal holding portion  133  (see  FIGS. 5 and 6 ), thereby preventing dislodging of the terminal  17 . 
   As shown in  FIGS. 13-23 , the connecting portion  172  includes a soldering region  174  that is an area to be soldered onto the inner conductor  302  of the coaxial cable  300 . Formed in the soldering region  174  is a recess or an elongated depression  174   a  taking the form of a pocket or well extending in the longitudinal direction of the connecting portion  172  and adapted to receive a fillet. As seen in cross section, the depression  174   a  has an arcuate bottom surface (see  FIGS. 13 and 21 ). The depression  174   a  is formed by stamping. The soldering region  174  is formed in one surface of the connecting portion  172  on the side opposite to inserting direction of the terminal  17  (the upper surface in  FIG. 13 ). Further, the soldering region  174  has a wide lateral width as compared with the other region of the connecting portion  172  of the terminal  17 , namely a termination surface or flat surface region  176  where the soldering region  174  is not formed. ( FIGS. 13-18 .) By thus forming the soldering region  174  that is laterally wide, a path, track or step  178  is formed at the boundary portion with another termination surface or flat surface region  176 . ( FIGS. 13-19 .) 
   Due to the step  178 , there is formed on either side surface of the connecting portion  172  a side wall or stepped portion  179  that is an island-like region extending continuously to the soldering region  174  and protruded with respect to a side surface region  175  that is the other side surface region of either side surface (see  FIGS. 13 through 20 ). The stepped portion  179  is formed by punching the non-stepped portion. 
   As shown in  FIGS. 4-6 , the intermediate portion  15  of the housing  7  has an inner insulator installation portion  151  where an inner insulator  304  of the coaxial cable  300  is installed. The same number of the inner insulator installation portions  151  as that of the coaxial cables  300  are formed in a continuous manner in the left-to-right direction. Further, the inner insulator installation portion  151  has a substantially horizontal S-shaped sectional configuration so as to provide a good seating for the inner insulator  304  when it is installed in the inner insulator installation portion  151 . Regarding the sectional configuration, the curvature of the portion where the inner insulator  304  is installed is set to be the same as the curvature of the inner insulator  304 . (FIGS.  4  &amp;  24 - 27 ). 
   The shell  9  of the connector  1  is made of conductive metal. Further, since the shell  9  serves to cover the housing  7 , like the housing, the shell  9  is shaped as an elongated quadrangle in plan view. ( FIG. 4 .) Further, the front edge of the shell  9  is formed as a folded portion  91  bent into a fold toward the rear side. ( FIG. 5 .) The rear portions of the opposite side edges of the shell  9  extend downwardly, forming side arms  93   f ,  93   r  having their respective distal ends folded inwardly so as to embrace the cable holding portion  11  of the housing  7  from both sides (see  FIGS. 1 and 4 ). At this time, both the side arms  93   f ,  93   r  are in abutment with the bottom portion of the ground bar  19  for electrical connection therewith. ( FIGS. 5 ,  8  &amp;  10 .) Further, formed in the opposite side edges at a position closer to the front edge are locking members  95   f ,  95   r  for mounting the connector  1  to the mating connector  2 . ( FIGS. 1 &amp; 2 .) 
   The locking members  95   f ,  95   r  each has a substantially U-shaped vertical section with its downwardly extending tongue member folded back upwardly at the central portion thereof. The locking members  95   f ,  95   r  exhibit a resilient force when applied with an external force acting to close the opening of the U-shape. Further, the distal ends of the locking members  95   f ,  95   r  are bent slightly sideways. 
   Formed substantially over the rear half portion of the ceiling surface of the shell  9  is a shallow flat recess  97  extending in the left-to-right direction along the rear edge of the ceiling surface. As shown in  FIG. 4 , the through holes  97 A,  97 B, into which the cable holders  16 A,  16 B are respectively inserted, are formed in the flat recess  97  in the same number as the number of the cable holders  16 A,  16 B (which is ten in the drawing). While, like the through holes  191 A,  191 B and the cable holder fitting holes  111 A,  111 B, the through holes  97 A,  97 B are also formed parallel to each other in the front-to-back direction but offset from each other in the left-to-right direction (FIGS.  4  &amp;  8 - 9 ), the through holes  97 A,  97 B are larger than those holes. When fitting the shell  9  over the housing  7 , the through holes  97 A,  97 B of the shell  9  are opposed to the through holes  191 A,  191 B of the ground bar  19  and the cable holder fitting holes  111 A,  111 B of the housing  7 , respectively ( FIGS. 5 &amp; 6 ). 
   The length of the respective legs or tines  16   b  of the cable holders  16 A and  16 B, the depth dimension of the cable holder fitting holes  111 A,  111 B of the housing  7 , and other various dimensions are selected such that when, as described above, the cable holders  16 A and  16 B are fit-engaged with the cable holder fitting holes  111 A,  111 B ( FIGS. 5 &amp; 6 ), the substrate portions  16   a  of the cable holders  16 A and  16 B are exposed and located within the through holes  97 A/ 97 B ( FIGS. 5 ,  6  &amp;  8 - 9 ). Further, the substrate portion  16   a  is formed slightly larger than the through holes  97 A,  97 B with respect to the width direction. Accordingly, when the cable holders  16 A and  16 B are fully fit-engaged with the housing  7 , the substrate portion  16   a  comes into an interference-fit with the through-holes  97 A/ 97 B, thereby preventing dislodging and providing secure electrical connection between the shell  9  and the cable holders  16 A,  16 B. 
   Typical mounting steps ( 1 ) through ( 6 ) for the connector  1  described above now are summarized with reference to  FIGS. 24-32  and their associated drawings. It is to be noted from  FIG. 5  that the illustrated coaxial cable  300  has a distal end portion  300   a  comprising a signal line  306  having a conductor  302  that is at an inner location within the cable. This inner conductor is exposed and not covered by the inner insulator  304 , or by another inner or intermediate sheath (or a sheath-remaining portion  310 ′). Also not covering these components is an outer shield or outside conductor  308  and an outside insulator  310 . In the illustrated arrangement, the distal edge of the sheath  310 ′ is situated immediately to the right or rear of the signal line  306 , the distal edge of the outside conductor  308  is situated close to the right or rear of the sheath  310 ′, and the distal edge of the outer insulator close to the right or rear of the outside conductor  308 . In this construction, the outer insulator  310  remains when shown, and the outside conductor  308  is exposed where only the outer insulator  310  is not present, such as by having been stripped off. ( FIGS. 5 &amp; 6 .) 
   In proceeding with step ( 1 ), each terminal  17  is inserted into the insertion hole  131  of the housing  7 , thereby attaching each terminal  17  to the housing  7 . This is illustrated in  FIGS. 4 ,  5  &amp;  24 - 25 . A next step, or step ( 2 ), attaches the ground bar  19  to the cable holding portion  11 . This is illustrated in  FIGS. 4 ,  5  &amp;  25 - 26 . 
   By step ( 3 ), the terminal  17  and the inner conductor  302  of the coaxial cable  300  are soldered together ( FIGS. 18-23  &amp;  27 ). In  FIGS. 18-23 , H denotes solder (linear solder). Further, reference symbol Hi denotes solder fusing device (pulse heat or soldering iron). 
   The soldering procedures are as follows. As shown in  FIGS. 18-21 , the solder H is placed on the depression  174   a  so as to be orthogonal to the longitudinal direction of the terminal  17 , and the inner conductor  302  of the coaxial cable  300  is placed on the solder H so as to be in parallel to the terminal  17 . This illustrates the soldering procedure of step ( 1 ). 
   Next, as shown in  FIGS. 19 &amp; 22 , the solder fusing device Hi is placed on the inner conductor  302  and subjected to heating, thus melting the solder. This illustrates the soldering procedure of step ( 2 ). As shown in  FIGS. 20 &amp; 23 , the fused solder H enters the depression  174   a  where it forms a fillet Fh (gradation portion), and the soldering is complete. This illustrates the procedure of step ( 3 ). 
   By a further procedure, namely step ( 4 ), the housing  7  with coaxial cables  300  soldered to the terminals  17  is covered with the shell  9 , which typically is a metal cover or otherwise strong and durable cover. This is illustrated in  FIGS. 27-28 . Thereafter, according to step ( 5 ), the cable holder  16 A is inserted into the through hole  97 A, the through hole  191 A, and the cable holder fitting hole  111 A.  FIGS. 5 ,  7 ,  8 ,  29 ,  30  &amp;  33 - 34  illustrate this. Step ( 6 ) inserts the cable holder  16 B into the through hole  97 B, the through-hole  191 B, and the cable holder fitting hole  111 B.  FIGS. 7 ,  9  &amp;  31 - 32  illustrate this procedure. 
   The mating connector  2  is described with reference to  FIGS. 1 ,  2  &amp;  5 - 6 . The mating connector  2  has a mating housing  21  formed of synthetic resin or other insulating resin. Mating terminals  27  are fitted on the mating housing  21  and brought into contact with the terminals  17  of the connector  1  upon fitting engagement between the connector  1  and the mating connector  2  ( FIG. 5 ) and a mating shell  29  covering the mating housing  21 . 
   The shape of the mating housing  21  is that of an elongated rectangle in plan view, which also is the shape of the housing  7 . Further, the mating housing  21  has mating terminal insertion portions  23  into which the mating terminals  27  are inserted and which are provided parallel to one another in the longitudinal direction (left-to-right direction) in the same number as that of the mating terminals  27  (see  FIGS. 1 and 5 ). Further, as can be seen in  FIG. 1 , formed on either side of the rear edge portion of the mating housing  21  is a locking protrusion  211  for mounting the mating shell  29  FIG. 
   Preferably, the mating terminal  27  is formed by machining a thin metal plate. As can be seen from  FIGS. 5 &amp; 6 , the mating terminal  27  has a main portion  271  having a substantially horizontal E-shaped configuration and an extending portion  273  having a substantially horizontal L-shaped configuration, with the main portion  271  and the extending portion  273  being connected in series in the front-to-rear direction. Further, the main portion  271  is provided with a press-fitting member  271   a  so that the mating terminal  27  is attached to the mating housing  21  by press-fitting the main portion  271  of the mating terminal  27  into the mating terminal insertion portion  23  of the mating housing  21  for fixation. A press-fitting hole  23   a  is provided in the mating terminal insertion portion  23  in an opposing relation to the press-fitting member  271   a . ( FIGS. 5 &amp; 6 .) 
   In the extending portion  273 , the terminal  17  is fitted inside a space S defined by the extending portion  273  upon connecting the connector  1  and the mating connector  2  together ( FIGS. 5-6 ). Further, the distal end of the extending portion  273  is formed as a protruding distal end portion  273   a  bent toward the terminal  17  side. Electrical connection is established between the connector  1  and the mating connector  2  as the distal end portion  273   a  comes into contact with the rear upright leg  171   r  of the terminal  17  of the connector  1 . 
   The mating shell  29  serves to mount the connector  1  and the mating connector  2  to each other as the mating shell  29  is coupled with the shell  9  of the connector  1 . The mating shell  29  covers the front edge and opposite side portions of the mating housing  21 . A regulation plate  291 , which serves to guide the connector  1  or prevent push-back of the connector  1  as it is brought into mating engagement with the mating connector  2 , is provided upright in the front edge portion of the mating connector  2 . Provided on opposite sides of the regulation plate  291  are cover portions  293   f ,  293   r  covering the opposite side portions of the mating housing  21  ( FIGS. 1-2 ) 
   The cover portions  293   f ,  293   r  are provided with engaging holes  295   f ,  295   r  engaging with the locking members  95   f ,  95   r  of the shell  9 , respectively ( FIGS. 1-2 ). The size of the engaging holes  295   f ,  295   r  in the width direction (left-to-right direction) is somewhat larger than the thickness dimension of the locking members  95   f ,  95   r  of the shell  9  in the state when the locking members  95   f ,  95   r  are not applied with an external force and hence their opening is not closed. Further, the distance between the engaging holes  295   f ,  295   r  is set to be slightly smaller than the distance between the locking members  95   f ,  95   r . In addition, formed in the rearward surface of each of the cover portions  293   f ,  293   r  is an engaging hole  297  to be engaged with the locking protrusion  211  of the mating housing  21 . To mount the illustrated connector  1  and the mating connector  2  together, the connector  1  is attached from above the mating connector  2  ( FIGS. 1 ,  2  &amp;  5 - 6 .) 
   At this time, the connector  1  and the mating connector  2  are aligned in their orientations such that the locking members  95   f ,  95   r  of the connector  1  enter the engaging holes  295   f ,  295   r , respectively, of the mating connector  2 . Since the engaging holes  295   f ,  295   r  are larger in their width direction (left-to-right direction) than the thickness dimension of the locking members  95   f ,  95   r  of the shell  9  at the time when no external force acts on the locking members  95   f ,  95   r , the locking members  95   f ,  95   r  are easily pushed into the engaging holes  295   f    295   r , respectively. Because the distance between the engaging holes  295   f ,  295   r  is set to be slightly smaller than the distance between the locking members  95   f    95   r , upon mounting the connector  1  and the mating connector  2  to each other, the locking members  95   f ,  95   r  of the connector  1  are each applied with an external force from the mating connector  2  which acts to close its opening. As a result, a resilient force develops in the locking members  95   f ,  95   r , which serves to prevent dislodging of the locking members  95   f ,  95   r  from the engaging holes  295   f ,  295   r , respectively. Accordingly, the connector  1  and the mating connector  2  are combined together with firm connection being established between the connector  1  and the mating connector  2 . 
   The operation and effects of the connector constructed as described above now are described. Because the depression  174   a  is formed in the terminal  17  of the connector  1 , the fused solder H is received within the depression  174   a . Accordingly, the majority of the fused solder H forms the fillet Fh within the depression  174   a  without spreading to the periphery of the depression  174   a  (see  FIGS. 18 through 23 ). Thus, as compared with the case of conventional terminals with no such depression  174   a  provided in the soldering region  174  ( FIG. 35   b ), there is relatively little or no spreading of the solder H over the surface of the terminal  17  (see  FIG. 35(   a )). Due to the formation of the fillet Fh in the depression  174   a , the connection between the terminal  17  and the fillet Fh becomes a three-dimensional one, causing an increase in connection surface area and/or volume, whereby the terminal  17   a  takes on a configuration as if a root has grown between the conductor  302  and the terminal  17  (see  FIG. 23) . 
   Further, as seen in cross-section in  FIG. 3 , the depression  174   a  has an arcuate bottom surface, whereby the bottom surface contacts the fused solder over a large contact area, larger for example than compared with the ordinary flat extent of the termination surface. This makes it possible to achieve an enhanced connection force between the terminal  17  and the inner conductor  302 . 
   Further, the sidewall stepped portion  179 , when provided, is an island-like region formed in the connector  1  that further accommodates excess solder should such be needed to prevent unwanted solder migration. With this arrangement, even when a somewhat large amount of fused solder H is present, as shown in  FIG. 35(   a ), the fused solder H spreads toward and around the periphery of the stepped portion  179 , whereby, as compared with the case where no stepped portion  179  is formed as shown in  FIG. 35(   b ), the fused solder H is prevented from unnecessarily spreading toward the other side surface region  175 . As a result, solder is prevented from flowing into the portions of the rear upright leg  171   r  which comes into contact with the distal end portion  273   a  of the mating terminal  27 . 
   It will be appreciated that the fillet Fh provides excellent strength to the connection between the inner conductor  302  and the coaxial cable  300 . As a result of the controlled shaping of the fillet during its formation, the strength of the force with which the inner conductor  302  of the coaxial cable  300  is connected to the terminal  17  through the fillet Fh can be retained even when the width dimension of the fillet Fh is reduced. Therefore, the width dimension of the terminal  17  can be reduced while maintaining the connection force between the terminal  17  and the inner conductor  302  without having to modify the conductor  302 . 
   Further, in the connector  1 , the fitting holes  111 A,  111 B into which the cable holders  16 A,  16 B are respectively fitted are provided in the housing  7 , and the through-holes  97 A,  97 B respectively opposed to the fitting holes  111 A,  111 B are provided in the shell  9 . 
   When the cable holders  16 A,  16 B are fitted into the fitting holes  111 A,  111 B via the through-holes  97 A,  97 B, respectively, the cable holders  16 A,  16 B are received within the housing  7  in a state of straddling and nipping the coaxial cables  300 , whereby no soldering is required to hold the coaxial cables  300  onto the housing  7 . 
   When the cable holders  16 A,  16 B are fitted into the cable holder fitting holes  111 A,  111 B via the through holes  97 A,  97 B, respectively, of the shell  9 , the substrate portion or backbone  16   a  is located within the through holes  97 A,  97 B (see  FIGS. 5 ,  6 ,  8  and  9 ). Comparing this structure with that of the case where the cable holders  16 A,  16 B are fitted into the cable holder fitting holes  111 A,  111 B of the housing  7  and then the housing  7  is covered with a shell having no through-holes  97 A,  97 B, respectively, provided that the length of the legs or tines  16   b  of the cable holders  16 A,  16 B, and also provided that the insertion amount of the legs or tines  16   b  into the cable holder fitting holes  111 A,  111 B are the same between the two structures, the cable holders  16 A,  16 B of the connector  1  have their respective substrate portions or backbones  16   a  exposed and located within the through holes  97 A,  97 B of the shell  9 , whereby the height dimension of the connector  1  can be reduced correspondingly. 
     FIG. 36  illustrates an actual comparative example, wherein  FIG. 36(   a ) shows the shell  9  according to this embodiment, and  FIG. 36(   b ) shows a connector  1 A to which a shell  9 A having no through-holes is applied. It can be appreciated from the drawings that the height dimension is reduced by a dimension C, that is by an amount corresponding to the thickness of the substrate portion or backbone  16   a  of the cable holder  16 A,  16 B which is exposed and located within the through-hole  97 A,  97 B of the shell  9 . It is to be noted that the same reference numerals are used to denote the same or like components in  FIGS. 36(   a ) and  36 ( b ). 
   Further, the connector  1  holds the coaxial cables  300  onto the housing  7  by using the cable holders  16 A,  16 B, and the coaxial cables  300  are very suitably and securely held in place onto the housing  7  without requiring any soldering. This feature prevents hardening of electric wires due to solder wicking. Furthermore, as counted from one end (the left side in  FIG. 4 ) of the large number of coaxial cables  300  arranged in parallel into a flat configuration, the odd-numbered coaxial cables  300 A and the even-numbered coaxial cables  300 B are held by different cable holders, namely the odd-numbered cable holders  16 A and the even-numbered cable holders  16 B, respectively. The cable holders  16 A,  16 B each can be arranged parallel in the front-to-rear direction but offset in the left-to-right direction with respect to one another, whereby the odd-numbered cable holders  16 A reliably hold solely the odd-numbered coaxial cables  300 A and the even-numbered cable holders  16 B reliably hold solely the even-numbered coaxial cables  300 B. Accordingly, it is possible to ensure that there is no single coaxial cable  300  that is insufficiently retained. 
   Further, the width W 2  of the cable holder fitting holes  111 A,  111 B is substantially the same as the width W 1  between adjacent legs  16   b , and the cable holder fitting holes  111 A,  111 B are hole portions each shaped like an inverted truncated isosceles triangle and tapered such that its width is large at the top and small at the bottom. Therefore, as the respective legs or tines  16   b  of the cable holders  16 A,  16 B are inserted into the cable holder fitting holes  111 A,  111 B of the housing  7 , the deeper the cable holders  16 A,  16 B are inserted into the cable holder fitting holes  111 A,  111 B, respectively, the narrower is the gap between the two legs or tines of the respective double-legged or double-tined portions of the cable holders  16 A,  16 B , leading to a corresponding increase in the force for holding the coaxial cable  300  sandwiched between the two legs or tines of the double-legged or double-tined portion. 
   Accordingly, connection reliability for the cables  300  is thus enhanced. Every single one of the coaxial cables  300  can be reliably grasped by pinching or nipping action solely by inserting the cable holders  16 A,  16 B into the cable holder fitting holes  111 A,  111 B, respectively. Furthermore, mechanical connection is effected on the coaxial cables  300  such that each coaxial cable  300  is sandwiched from above and below by the substrate portion or backbone  16   a  of each of the cable holders  16 A,  16 B and the ground bar  19 , respectively, and such that the pair of legs or tines  16   b ,  16   b  constituting the double-legged or double-tined portion sandwich the coaxial cable  300  from the left and right sides. Further, as described above, upon inserting the cable holders  16 A,  16 B into the cable holder fitting holes  111 A,  111 B, respectively, the outer conductor  308  of the coaxial cable  300  is sandwiched from below and above by the ground bar  19 , which is in contact with the shell  9  through both of its side arms  93   f ,  93   r  and the cable holders  16 A,  16 B, respectively, for electrical connection. ( FIGS. 5 ,  6 ,  8  &amp;  33 - 34 .) Therefore, the cable holders  16 A,  16 B can effect both electrical and mechanical connections of the coaxial cable  300  at the same time, thereby achieving an improvement in operability. In addition, while the coaxial cable connector exemplified in this embodiment is the coaxial cable (braided coaxial cable) including the outer conductor covering the signal line  306  and consisting of the large number of spirally wound or braided electric wires, as long as it is used solely for soldering the terminal  17 , a coaxial cable of a so-called semi-rigid structure whose outer conductor is made of a copper tube, or a so-called discrete cable other than the coaxial cable, also may be used. 
   It will be understood that the embodiments of the present invention which have been described are illustrative of some of the applications of the principles of the present invention. Numerous modifications may be made by those skilled in the art without departing from the true spirit and scope of the invention. Various features which are described herein can be used in any combination and are not limited to procure combinations that are specifically outlined herein.