Patent Publication Number: US-11025009-B2

Title: Circuit substrate mounted cable connector

Description:
RELATED APPLICATIONS 
     This application claims priority to Japanese Application No. 2018-245717 filed on Dec. 27, 2018, which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to a connector assembly. 
     BACKGROUND ART 
     Patent Document 1 discloses a connector assembly for electrically connecting a circuit substrate and a cable. In Patent Document 1, the circuit substrate mounted on a connector (referred to as a “substrate connector”) can mate with a connector for holding a cable terminal (referred to as a “cable connector”) in the vertical direction. The cable connector is disposed on the upper side of the substrate connector and is fitted in the left and right side walls of the substrate connector. A recess is formed on the inner surface of the side walls of the substrate connector, while a projection engaging with the recess of the substrate connector is formed on the left and right side faces of the cable connector. This recess and projection restrict separation of the two connectors. 
     Patent Document: Patent Document 1: JP 4115983 B 
     SUMMARY 
     When a cable connector mates with a substrate connector, a force pulling a cable diagonally rearward may act. In order to prevent such a force from separating the two connectors, it is effective to increase an engagement force of the two connectors (degree of engagement of recess and projection). Unfortunately, in the structure of Patent Document 1, when the degree of engagement between the recess and the projection increases, a force required for an operator to mate and separate the two connectors is excessive, deteriorating the workability. That is, in the conventional structure, it is problematically difficult to improve the resistance to the force pulling a cable diagonally rearward while maintaining the workability of the operation of mating and separating the two connectors. 
     A connector assembly proposed in the present disclosure includes: a first connector which can be mounted on a circuit substrate; and a second connector which is capable of mating with the first connector in the vertical direction and holds a cable terminal provided at the end of a cable, wherein the cable is capable of being connected to the second connector so as to extend rearward. The first connector has a first rear engagement part exposed towards the rear of the first connector, along with a first front engagement part exposed towards the front of the first connector. The second connector has a second rear engagement part and a second front engagement part. In the mating state between the first connector and the second connector, the second rear engagement part is disposed on the rear side of the first rear engagement part so as to engage with the first rear engagement part, while the second front engagement part is disposed on the front side of the first front engagement part so as to engage with the first front engagement part. 
     This connector assembly can effectively prevent a first connector and a second connector from separating if a cable is pulled diagonally rearward, for example. Moreover, this can facilitate the operation of engaging the second rear engagement part of the second connector with the first rear engagement part of the first connector. 
     Note that in this connector assembly, the cable and the cable terminal are not elements of the second connector. When using the second connector, the cable terminal may be held by the second connector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of one example of a connector assembly proposed by the present disclosure. 
         FIG. 2A  is a perspective view of the connector assembly. 
         FIG. 2B  is a perspective view of the connector assembly. 
         FIG. 3A  is a diagram illustrating the mating process of two connectors which form the connector assembly. 
         FIG. 3B  is a diagram illustrating the mating process of two connectors which form the connector assembly. 
         FIG. 3C  is a diagram illustrating the mating process of two connectors which form the connector assembly. 
         FIG. 4A  is a side view illustrating the rear part of the connector assembly. 
         FIG. 4B  is a side view illustrating the front part of the connector assembly. 
         FIG. 5  is a front view of the connector assembly. 
         FIG. 6A  is an exploded perspective view of a first connector. 
         FIG. 6B  is a perspective view illustrating the front side of the first connector. 
         FIG. 6C  is a front view of the first connector. 
         FIG. 6D  is a side view of the first connector. 
         FIG. 7A  is an exploded perspective view of a second connector. 
         FIG. 7B  is a perspective view illustrating the front side of the second connector. 
         FIG. 8  is a plan view illustrating the state in which the first rear engagement part of the first connector engages with the second rear engagement part of the second connector. 
         FIG. 9A  is a perspective view of a cable terminal. 
         FIG. 9B  is a front view illustrating the state in which the cable terminal and a terminal of the first connector are connected. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A connector assembly proposed in the present disclosure is described below. The present specification describes a connector assembly  1  illustrated in  FIG. 1  and the like as an example of a connector assembly. In the following description, the directions indicated by X 1  and X 2  in  FIG. 1  are respectively referred to as right and left, while the directions indicated by Y 1  and Y 2  in  FIG. 1  are respectively referred to as forward and backward. Moreover, the directions indicated by Z 1  and Z 2  are respectively referred to as up and down. While these directions are used to describe the relative positional relationships of parts, members, and sections that make up a connector assembly, they do not limit the orientation of the connector assembly  1  when used. 
     As illustrated in  FIG. 1 , the connector assembly  1  has a first connector  10  and a second connector  60 . The two connectors  10  and  60  can mate with each other in the anteroposterior direction. The connector assembly  1  is a connector assembly for electrically connecting a circuit substrate  101  (see  FIGS. 2A and 2B ) and multiple cables  90 . The first connector  10  is a connector mounted on the circuit substrate  101 , while the second connector  60  is a connector with the cable  90  connected thereto. 
     As illustrated in  FIG. 1 , the first connector  10  may have a housing  20 , along with terminals  11  installed in the housing  20 . The housing  20  is, for example, integrally molded of a resin. The terminals  11  are formed of a conductive material (for example, copper) and connected to a conductive pad formed on the circuit substrate  101 . For example, the terminals  11  are soldered to the conductive pad. The first connector  10  may have multiple terminals  11  arranged in the left and right direction. While the number of the terminals  11  is, for example, two, as illustrated in  FIG. 1 , the number may be one or three. The housing  20  may have left and right side walls  21 R,  21 L formed in the anteroposterior direction, along with a front wall  22  formed between the frontmost parts of the left and right side walls  21 R,  21 L. The terminals  11  are fixed to the front wall  22 . Moreover, the housing  20  may have a bottom  29  formed between the lower edges of the left and right side walls  21 R,  21 L. The housing  20  opens upward and rearward. 
     A hole  22   a  (see  FIG. 6A ) penetrating through the front wall  22  in the anteroposterior direction is formed in the front wall  22 . The terminals  11  are fixed inside this hole  22   a . The front and rear parts of the terminals  11  respectively protrude forward and rearward from the front wall  22 . The terminals  11 , for example, are pressed into the hole  22   a  and fixed. Unlike this, the terminals  11  may be insert molded in the first housing  20 . That is, in the process of molding the first housing  20  from molten resin, the terminals  11  may be solidified with the resin. 
     As illustrated in  FIGS. 1 and 7A , the second connector  60  may hold a cable terminal  91  installed at the end of each cable  90 . The cables  90  are connected to the second connector  60  so as to extend rearward from the second connector  60 . Multiple cables  90  arranged in the left and right direction may be connected to the second connector  60 . While the number of the cables  90  connected to the second connector  60  is, for example, two, the number may be one or three. In the mating state between two connectors  10 ,  60 , multiple cable terminals  91  are respectively connected to multiple terminals  11  provided in the first connector  10 . 
     As illustrated in  FIG. 7A , the second connector  60  is, for example, integrally molded of resin. The second connector  60  may have a terminal holding part  61  for holding multiple cable terminals  91 . A holding hole  61   a  extending from the rear end towards the front side thereof extend is formed at the terminal holding part  61 . The cable terminals  91  are inserted into this holding hole  61   a  and fixed. The holding hole  61   a  opens downward at the frontmost part of the terminal holding part  61  (see  FIG. 7B ). 
     In the mating state between the first connector  10  and the second connector  60 , the terminal holding part  61  of the second connector is disposed between the left and right side walls  21 R,  21 L of the first connector  10 . In addition, the terminals  11  are fitted in the holding hole  61   a  so as to contact the frontmost part of the cable terminal  91 . The shape of the cable terminals  91  will be described below. 
     As illustrated in  FIG. 1 , the first connector  10  (specifically, the housing  20 ) may have first rear engagement parts  24 A,  24 B. The first rear engagement parts  24 A,  24 B are formed on the left and right side walls  21 R,  21 L. Specifically, the first rear engagement parts  24 A,  24 B are formed at the rear ends of the left and right side walls  21 R,  21 L. In addition, the first rear engagement parts  24 A,  24 B are exposed towards the rear of the first connector  10 . That is, as seen from the back of the first connector  10 , no part of the first connector  10  overlaps the first rear engagement parts  24 A,  24 B. Moreover, as illustrated in  FIGS. 2B and 6B , the first connector  10  (specifically, the housing  20 ) may have first front engagement parts  23 A,  23 B. The first front engagement parts  23 A,  23 B are, for example, formed at the front surface of the front wall  22  and exposed towards the front of the first connector  10 . Two first front engagement parts  23 A,  23 B separated in the left and right direction may be formed on the front wall  22 . The number of the first front engagement parts  23 A,  23 B is not limited to two and, for example, may be one or three or more. 
     In contrast, as illustrated in  FIG. 1 , the second connector  60  may have second rear engagement parts  64 A,  64 B at the rear part of the second connector  60 . The second rear engagement parts  64 A,  64 B, for example, respectively protrude outward in the left and right direction from the left and right side faces  61   b  of the terminal holding part  61 . Moreover, as illustrated in  FIGS. 2B and 7B , the second connector  60  may have second front engagement parts  63 A,  63 B. The second connector  60  has a front extension part  62  extending forward from the terminal holding part  61 . The second front engagement parts  63 A,  63 B are, for example, formed at the front edge of the front extension part  62  so as to extend downward from the front extension part  62 . 
     As illustrated in  FIGS. 1 and 2A , the second rear engagement parts  64 A,  64 B are respectively disposed on the rear side of the first rear engagement parts  24 A,  24 B so as to engage with the second rear engagement parts  24 A,  24 B. Specifically, the front end of the second rear engagement parts  64 A,  64 B is disposed on the lower side of the below-mentioned inclined surface  24   c  (see  FIG. 4A ) formed in the first rear engagement parts  24 A,  24 B. Moreover, as illustrated in  FIG. 2B , in the mating state between the two connectors  10 ,  60 , the second front engagement parts  63 A,  63 B are respectively disposed on the front side of the first front engagement parts  23 A,  23 B so as to engage with the first front engagement parts  23 A,  23 B. That is, the lowermost part of the second front engagement parts  63 A,  63 B is disposed on the lower side of the below-mentioned contact surface  23   a  (see  FIG. 6B ) formed in the first front engagement parts  23 A,  23 B. Therefore, in the mating state between the connectors  10 ,  60 , the first connector  10  is sandwiched by the second front engagement parts  63 A,  63 B and the second rear engagement parts  64 A,  64 B of the second connector  60  in the anteroposterior direction. 
     The second connector  60  can rotate relative to the first connector  10  about the second rear engagement parts  64 A,  64 B engaging with the first rear engagement parts  24 A,  24 B. Specifically, in the process of mating the connectors  10 ,  60 , the second connector  60  is first disposed in a position so as to be inclined to the first connector  10  such that the second rear engagement parts  64 A,  64 B engage with the first rear engagement parts  24 A,  24 B (see  FIG. 3A ). When the front part of the second connector  60  is lowered centering around the second rear engagement parts  64 A,  64 B, the second front engagement parts  63 A,  63 B abut the front surface of the first front engagement parts  23 A,  23 B (see  FIG. 3B ) and slide downward on the front surface (the below-mentioned guide surface  23   b ) of the first front engagement parts  23 A,  23 B. In addition, the lowermost part of the second front engagement parts  63 A,  63 B reaches the lower side of the lower surface (contact surface  23   a ) of the first front engagement parts  23 A,  23 B (see  FIG. 3C ). In the process of separating the connectors  10 ,  60 , in contrast to the mating process, the front part of the second connector  60  is raised centering around the second rear engagement parts  64 A,  64 B. 
     In this way, because the second rear engagement parts  64 A,  64 B are respectively disposed on the rear side of the first rear engagement parts  24 A,  24 B so as to engage with the first rear engagement parts  24 A,  24 B, an operator can rotate the second connector  60  about the second rear engagement parts  64 A,  64 B. By rotating the second connector  60 , the operator can engage and disengage the second front engagement parts  63 A,  63 B as well as the first front engagement parts  23 A,  23 B. 
     Because the second front engagement parts  63 A,  63 B are disposed on the front side of the first front engagement parts  23 A,  23 B, when the second front engagement parts  63 A,  63 B and the first front engagement parts  23 A,  23 B are disengaged, the second front engagement parts  63 A,  63 B move in the direction of the arrow D 1  illustrated in  FIG. 4B  (diagonally forward and upward). The force pulling the cable  90  diagonally rearward and upward acts on the second front engagement parts  63 A,  63 B and the first front engagement parts  23 A,  23 B. When the cable  90  is pulled diagonally rearward and upward, the force in the direction indicated by D 2  of  FIG. 4B  (diagonally rearward and upward) acts on the second front engagement parts  63 A,  63 B. That is, the direction D 2  of the force acting when the cable  90  is pulled is significantly different from the direction D 1  for disengaging the second front engagement parts  63 A,  63 B and the first front engagement parts  23 A,  23 B. As a result, two connectors  10 ,  60  can be effectively prevented from separating when the cable  90  is pulled diagonally rearward and upward. 
     Moreover, in the mating state between the connectors  10 ,  60 , the second rear engagement parts  64 A,  64 B are respectively disposed on the rear side of the first rear engagement parts  24 A,  24 B so as to engage with the first rear engagement parts  24 A,  24 B. As mentioned below, the upper part  24   a  (see  FIG. 4A ) of the first rear engagement parts  24 A,  24 B is disposed above the second rear engagement parts  64 A,  64 B. According to this structure, when the cable  90  is diagonally forward and upward, the upper part  24   a  of the first rear engagement parts  24 A,  24 B can restrict the movement of the second rear engagement parts  64 A,  64 B, effectively preventing the two connectors  10 ,  60  from separating. 
     As mentioned above, the first rear engagement parts  24 A,  24 B of the first connector  10  are exposed towards the rear of the first connector  10 . That is, as seen from the back of the first connector  10 , no part of the first connector  10  overlaps the first rear engagement parts  24 A,  24 B. That is, when seeing the first connector  10  from right behind, the operator can see the first rear engagement parts  24 A,  24 B. As a result, in the operation process of mating the second connector  60  with the first connector  10 , the operator can easily abut the second rear engagement parts  64 A,  64 B against the first rear engagement parts  24 A,  24 B, thereby improving the workability. 
     In the example of the first connector  10 , the first rear engagement parts  24 A,  24 B serve as the rear end surfaces of the left and right side walls  21 R,  21 L. As a result, with the second rear engagement parts  64 A,  64 B engaging with the first rear engagement parts  24 A,  24 B, the second rear engagement parts  64 A,  64 B are laterally exposed, allowing the operator to easily confirm the positions of the second rear engagement parts  64 A,  64 B. Therefore, this can particularly facilitate the operation of abutting the second rear engagement parts  64 A,  64 B against the first rear engagement parts  24 A,  24 B. 
     Moreover, because the first rear engagement parts  24 A,  24 B serve as the rear end surfaces of the left and right side walls  21 R,  21 L, when something unintended by the operator is caught by the cable  90  and the cable  90  is pulled rightward or leftward, the distance between the part for receiving the force (portion of the cable  90 ) and the first rear engagement parts  24 A,  24 B becomes closer. As a result, the resistance to moments generated in the connectors  10 ,  60  caused by such a force can be improved. 
     As illustrated in  FIG. 3C , in the mating state between the two connectors  10 ,  60 , a gap may be formed between the first front engagement parts  23 A,  23 B (the below-mentioned contact surface  23   a  ( FIG. 4B )) and the second front engagement parts  63 A,  63 B, while a gap may be formed between the first rear engagement parts  24 A,  24 B and the second rear engagement parts  64 A,  64 B (the below-mentioned contact surface  64   a ). According to this structure, in the mating state between the two connectors  10 ,  60 , as well as in the process of reaching the mating state, excessive loads can be prevented from being applied between the first front engagement parts  23 A,  23 B and the second front engagement parts  63 A,  63 B, in addition to excessive loads being prevented from being applied between the first rear engagement parts  24 A,  24 B and the second rear engagement parts  64 A,  64 B. 
     The positions of the first rear engagement parts  24 A,  24 B are not limited to the example of the first connector  10 . For example, the first rear engagement parts  24 A,  24 B may be formed on the inner surfaces of the left and right side walls  21 R,  21 L. A step, for example, may be formed on the inner surfaces of the left and right side walls  21 R,  21 L, such that this step may form the surface which is exposed rearward. In addition, this surface which is exposed rearward may function as the first rear engagement parts  24 A,  24 B. 
     Rear engagement parts  24 A,  24 B,  64 A, and  64 B will hereinafter be described in detail. Because the shape of two first rear engagement parts  24 A,  24 B, as well as that of the shape of two second rear engagement parts  64 A,  64 B, is symmetric, the rear engagement parts  24 A,  64 A formed on the right will hereinafter be mainly described. The descriptions of the rear engagement parts  24 A,  64 A formed on the right also apply to the rear engagement parts  24 B,  64 B formed on the left. 
     As illustrated in  FIG. 4A , the second rear engagement part  64 A may have the contact surface  64   a  which abuts the first rear engagement part  24 A and is curved when seen from the side of the second connector  60 . This contact surface  64   a  is arc shaped about the straight line L 3  (see  FIG. 1 ) in the left and right direction which passes through the second rear engagement part  64 A. The contact surface  64   a , for example, forms a semicircle about the straight line L 3 . In the operation process of mating the second connector  60  with the first connector  10 , as well as the operation process of separating the first connector  10  and the second connector  60 , this shape of the contact surface  64   a  enables the second connector  60  to smoothly rotate about the left and right second rear engagement parts  64 A,  64 B. 
     As illustrated in  FIG. 4A , the first rear engagement part  24 A may have the upper part  24   a  which is disposed above the contact surface  64   a  of the second rear engagement part  64 A. The presence of the upper part  24   a  can prevent the first rear engagement part  24 A from being unintentionally separated from the second rear engagement part  64 A. 
     As illustrated in  FIG. 4A , the first rear engagement part  24 A may have a vertical surface  24   b , along with the first inclined surface  24   c  which extends diagonally rearward and upward from the vertical surface  24   b . The contact surface  64   a  of the second rear engagement part  64 A faces the vertical surface  24   b  along with the lower part of the first inclined surface  24   c . In the operation process of engaging the second rear engagement part  64 A and the first rear engagement part  24 A, when the second rear engagement part  64 A abuts the upper part of the first inclined surface  24   c  of the first rear engagement part  24 A, the second rear engagement part  64 A is guided downward by the first inclined surface  24   c . That is, the first inclined surface  24   c  may function as a guide surface. 
     Moreover, as illustrated in  FIG. 4A , the first rear engagement part  24 A may have a second inclined surface  24   d  which extends from the upper part of the first inclined surface  24   c . The second inclined surface  24   d  is inclined in front of the straight line in the vertical direction. That is, the second inclined surface  24   d  extends diagonally forward and upward from the upper part of the first inclined surface  24   c . Specifically, the second inclined surface  24   d  extends diagonally forward and upward while being curved in an arc shape. Unlike this, the second inclined surface  24   d  may linearly extend diagonally forward and upward from the upper part of the first inclined surface  24   c.    
     In the operation process of engaging the second rear engagement part  64 A and the first rear engagement part  24 A, even when the second rear engagement part  64 A approaches the first rear engagement part  24 A from the upper side and abuts the upper part  24   a  of the first rear engagement part  24 A, the second rear engagement part  64 A is guided by the second inclined surface  24   d  so as to slide rearward and be disposed on the rear side of the first rear engagement part  24 A. Therefore, the second inclined surface  24   d  can facilitate the operation of engaging the second rear engagement part  64 A and the first rear engagement part  24 A. 
     The shape of the first rear engagement part  24 A is not limited to the example of the first connector  10 . For example, the first rear engagement part  24 A may not have the vertical surface  24   b . In this case, the inclined surface  24   c  may be formed over the entire first rear engagement part  24 A, that is, over the entire rear end surface of the right side wall  21 R. As yet another example, the first rear engagement part  24 A does not necessarily have to have the inclined surface  24   c  as long as it is of a shape which restricts the upward movement of the second rear engagement part  64 A. As yet another example, the inclined surface  24   c  linearly extends, but may be curved. 
     As illustrated in  FIG. 4A , the second rear engagement part  64 A has a rear part  64   b  which is disposed behind the upper part  24   a  of the first rear engagement part  24 A. In doing so, the width of the second rear engagement part  64 A in the anteroposterior direction tends to be sufficiently assured, while the strength of the second rear engagement part  64 A to the force received from the first rear engagement part  24 A tends to be assured. The width W 2  in the anteroposterior direction of the rear part  64   b  is, for example, larger than the width W 1  in the part with the contact surface (curved surface)  64   a  formed therein. 
     The structure of the rear engagement parts  24 A,  64 A is not limited to the example indicated by the connectors  10 ,  60 . For example, the contact surface (arc shaped contact surface) which allows smooth rotation of the second connector  60  may be formed in the first rear engagement part  24 A. For example, the first rear engagement part  24 A may protrude rearward from the side wall  21 R of the first connector  10 . In this case, the rear end surface of the first rear engagement part  24 A (surface abutting the second rear engagement part) may be curved in an arc shape. Moreover, in this case, the second rear engagement part  64 A may not have a curved contact surface. As yet another example, the first rear engagement part  24 A may protrude inward from the inner surface of the side wall  21 R of the first connector  10 . In this case, the rear surface of the first rear engagement part  24 A (surface abutting the second rear engagement part) may be curved in an arc shape. 
     As illustrated in  FIG. 1 , the first connector  10  may have a reinforcing metal fitting  31  adjacent to the first rear engagement parts  24 A,  24 B. The reinforcing metal fitting  31  enables the strength of the first rear engagement parts  24 A,  24 B to increase and, for example, can effectively prevent the first rear engagement parts  24 A,  24 B from being deformed by the force received from the second rear engagement parts  64 A,  64 B. The reinforcing metal fitting  31  is, for example, installed in the rear part of each of the left and right side walls  21 R,  21 L. The reinforcing metal fitting  31  is plate shaped and disposed so as to face the left and right direction. 
     As illustrated in  FIG. 4A , the lower edge  31   a  of the reinforcing metal fitting  31  may be disposed below the lower surface of the first connector  10 . The lower edge  31   a  of the reinforcing metal fitting  31  may be installed in the circuit substrate  101 . For example, the lower edge  31   a  of the reinforcing metal fitting  31  may be soldered to the circuit substrate  101 . According to this structure, the force acting from the second rear engagement part  64 A on the first rear engagement part  24 A can be prevented from acting on the connection between the terminal  11  and a conductive pad of the circuit substrate  101 . 
     As illustrated in  FIG. 4A , when the two connectors  10 ,  60  mate with each other, the reinforcing metal fitting  31  is disposed in front of the second rear engagement parts  64 A,  64 B. The position of the upper part  31   b  of the reinforcing metal fitting  31  is higher than the second rear engagement part  64 A. Moreover, as in the upper part  24   a  of the first rear engagement part  24 A, the upper part  31   b  of the reinforcing metal fitting  31  protrudes rearward. 
     As illustrated in  FIG. 8 , in a plan view of the connectors  10 ,  60 , the reinforcing metal fitting  31  is disposed so as to be closer to the center of the first connector  10  in the left and right direction compared with the end surface  64   c  of the second rear engagement part  64 A (end outward in the left and right direction). In other words, the straight line L 1  passing through the reinforcing metal fitting  31  in the anteroposterior direction also passes through the second rear engagement part  64 A. According to this disposition of the reinforcing metal fitting  31 , the reinforcing metal fitting  31  can effectively receive the force acting from the second rear engagement part  64 A on the first rear engagement part  24 A. 
     As illustrated in  FIG. 6A , a hole  21   a  penetrating through the side wall  21 R in the vertical direction is formed in the side wall  21 R (see  FIG. 6A ), while the reinforcing metal fitting  31  is pressed into this hole  21   a  and fixed to the side wall  21 R. The reinforcing metal fitting  31  may be formed by insert molding with a housing  20  including the side wall  21 R. 
     As illustrated in  FIG. 2B , the first connector  10  may have multiple first front engagement parts  23 A,  23 B separated in the left and right direction. Similarly, the second connector  60  may have multiple second front engagement parts  63 A,  63 B separated in the left and right direction. For example, the first connector  10  has two first front engagement parts  23 A,  23 B, while the second connector  60  has two second front engagement parts  63 A,  63 B. In the first connector  10 , multiple terminals  11  (specifically, two terminals  11 ) are disposed between the two first front engagement parts  23 A,  23 B. 
     The number and position of front engagement parts  23 A,  23 B,  63 A,  63 B are not limited to the example of the connectors  10 ,  60 . For example, the first connector  10  may have a first front engagement part formed between the terminals  11 , in addition to the two first front engagement parts  23 A,  23 B or in place of the two first front engagement parts  23 A,  23 B. In this case, the second connector  60  has a second front engagement part corresponding to the first front engagement part formed between the terminals  11 . 
     The width in the left and right direction of the second front engagement part  63 B formed on the left may be slightly larger than the width of the second front engagement part  63 A formed on the right (see  FIG. 5 ). Accordingly, the width in the left and right direction of the first front engagement part  23 B formed on the left may be slightly larger than the width of the second front engagement part  23 A formed on the right. With the exception of this point, the shape of the two first front engagement parts  23 A,  23 B, as well as that of the two second front engagement parts  63 A,  63 B, is substantially symmetric. With that, the front engagement parts  23 A,  63 A formed on the right will hereinafter be mainly described. The descriptions of the front engagement parts  23 A,  63 A formed on the right also apply to the front engagement parts  23 B,  63 B formed on the left. 
     As illustrated in  FIG. 4B , the first front engagement part  23 A may have the contact surface  23   a  at the lower part thereof. The tip (lower end) of the second front engagement part  63 A is disposed below and in front of the contact surface  23   a , such that the contact surface  23   a  contacts the second front engagement part  63 A. For example, when the cable  90  is pulled and the second connector  60  moves rearward, the contact surface  23   a  contacts the second front engagement part  63 A. Moreover, when the second connector  60  rotates about the second rear engagement part  64 A, the tip (lower end) of the second front engagement part  63 A abuts the contact surface  23   a . Consequently, the second connector  60  can be prevented from unintentionally rotating and separating from the first connector  10 . Unlike the example of the connectors  10 ,  60 , the dimensions of the connectors  10 ,  60  may be designed such that in the mating state between the connectors  10 ,  60 , the contact surface  23   a  continuously contacts the second front engagement part  63 A. 
     As illustrated in  FIG. 4B , the contact surface  23   a  may extend diagonally forward and upward from the front surface of the front wall  22 . According to this inclination of the first front engagement part  23 A, when the force pulling the cable  90  diagonally rearward and upward acts, the direction of the force is substantially vertical to the contact surface  23   a . As a result, the second connector  60  can effectively be prevented from separating from the first connector  10  when the cable  90  is pulled. 
     As illustrated in  FIG. 4B , the second front engagement part  63 A of the second connector  60  may also have a contact surface  63   a  extending diagonally forward and upward at the lower part thereof. In doing so, when the force pulling the cable  90  diagonally rearward and upward acts, a large extent of the contact surface  63   a  of the second front engagement part  63 A abuts the contact surface  23   a  of the first front engagement part  23 A. Consequently, excessive stress can be prevented from acting on only a portion of the contact surface  63   a.    
     Moreover, as illustrated in  FIG. 4B , the contact surface  23   a  is inclined to the plane P 1  which passes through the rotation center (line L 3  illustrated in  FIG. 1 ) of the second connector  60  along with the contact surface  23   a . Specifically, the contact surface  23   a  is inclined to the upper side with respect to the plane P 1 . For example, compared with the case in which the contact surface  23   a  is parallel to the plane P 1 , this structure can facilitate the operation of disengaging the second front engagement part  63 A and the first front engagement part  23 A. 
     The structure of the front engagement parts  23 A,  63 A is not limited to the example of the connectors  10 ,  60 . For example, the contact surface  23   a  of the first front engagement part  23 A may be curved in an arc shape. In yet another example, the contact surface  23   a  may, for example, be parallel to the plane P 1 . In this case, the contact surface  63   a  of the second front engagement part  63 A may extend forward and upward diagonally or be curved in an arc shape. 
     As illustrated in  FIG. 6D , the first front engagement part  23 A has a guide surface  23   b  which extends diagonally upward and rearward from the front end of the contact surface  23   a . In the operation process of mating the second connector  60  with the first connector  10 , the tip (lower end) of the second front engagement part  63 A slides towards the contact surface  23   a  on this guide surface  23   b.    
     As illustrated in  FIG. 6D , the guide surface  23   b  has a relatively long length W 4  in the vertical direction. Specifically, the length W 4  of the guide surface  23   b  may be longer than the length W 3  of the contact surface  23   a . Moreover, the length W 4  of the guide surface  23   b  may be longer than half the height h 1  of the side wall  21 R of the first connector  10 . By lengthening the guide surface  23   b  in this way, any increase in the force (frictional force) acting on the second front engagement part  63 A is moderated in the operation process of mating the second connector  60  with the first connector  10 . In other words, the impact acting on the second front engagement part  63 A can be moderated. 
     As illustrated in  FIG. 6D , in the second connector  60 , the position of the upper end  23   c  of the guide surface  23   b  may be higher than the upper end  22   c  of the front wall  22 . This structure can prevent the tip (lower end) of the second front engagement part  63 A of the second connector  60  from colliding with the upper end  22   c  of the front wall  22 . The upper end  23   c  of the guide surface  23   b  may be higher than the position of the upper end  11   b  of the terminal  11 . 
     The guide surface  23   b  of the second front engagement part  63 A may have a projection  23   d  at the lowermost part thereof which swells forward. That is, the inclination of the guide surface  23   b  in the vertical direction is steeper in the projection  23   d . According to this structure, in the operation process of mating the second connector  60  with the first connector  10 , when the lower end of the second front engagement part  63 A reaches the projection  23   d , the force required to operate (rotate) the second connector  60  instantaneously increases; in contrast, when the lower end of the second front engagement part  63 A exceeds the projection  23   d , the force required to operate (rotate) the second connector  60  sharply drops. Such a drop in force enables an operator to recognize that the second front engagement part  63 A has properly engaged with the first front engagement part  23 A, without viewing the position of the tip (lower end) of the second front engagement part  63 A. 
     As mentioned above, the terminal  11  is installed on the front wall  22  of the first connector  10 . The terminal  11  is formed of metal and fixed to a conductive pad of the circuit substrate  101  when using the first connector  10 . The first front engagement part  23 A is formed on this the front wall  22 . According to this structure, the terminal  11  can increase the strength of the front wall  22 . Consequently, the front wall  22  can be prevented from being deformed when the second front engagement part  63 A pushes the guide surface  23   b  of the first front engagement part  23 A. 
     As illustrated in  FIG. 6C , the first front engagement part  23 A may be adjacent to the terminal  11 . Specifically, the edge of the first front engagement part  23 A may be congruent with the edge  22   b  of the hole  22   a  ( FIG. 6A ) with the terminal  11  fitted therein. More specifically, the first front engagement part  23 A formed on the right is formed further on the right of the right terminal  11 , while the left edge of the first front engagement part  23 A may be congruent with the edge  22   b  of the hole  22   a . In this way, because the position of the first front engagement part  23 A is close to the terminal  11  and this terminal  11  is fixed to the circuit substrate  101 , the position of the first front engagement part  23 A can be effectively prevented from being recessed when the second front engagement part  63 A pushes the guide surface  23   b  of the first front engagement part  23 A. 
     Note that the member reinforcing the front wall  22  may not be the terminal  11 . That is, a metal member which is not utilized for electrically connecting the circuit substrate  101  and the cable  90 , but which is fixed (for example, soldered) to the circuit substrate  101 , may be installed on the front wall  22 . 
     As illustrated in  FIG. 6B , the front wall  22  may have a reinforcing part  25  which is disposed between two first front engagement parts  23 A,  23 B and swells forward. The reinforcing part  25  is, for example, formed between two terminals  11 . According to this structure, it is possible to increase the rigidity of the front connector  22 . Consequently, in the operation process of mating the second connector  60  with the first connector  10 , the front wall  22  can be prevented from being deformed when the second front engagement parts  63 A,  63 B push the guide surface  23   b  of the first front engagement parts  23 A,  23 B. 
     The reinforcing part  25  may have the same shape as the first front engagement parts  23 A,  23 B. That is, the reinforcing part  25  may have an inclined surface  25   a  which extends diagonally downward and forward. The height of the upper end of the inclined surface  25   a  is, for example, the same as the height of the guide surface  23   b  of the first front engagement part  23 A (see  FIG. 6D ). The positions of the right and left ends of the reinforcing part  25  may be congruent with the edge of the hole  22   a  with the two terminals  11  fitted therein. 
     As illustrated in  FIG. 7B , in the second connector  60 , a front extension part  62  extends forward from a terminal holding part  61 . In the mating state between the first connector  10  and the second connector  60 , the front extension part  62  is formed so as to cover the entire upper side of the front wall  22  of the first connector  10 . As illustrated in  FIG. 7B , the second front engagement parts  63 A,  63 B are formed at the front edge of the front extension part  62 . The second front engagement parts  23 A,  23 B extend downward from the front edge of the front extension part  62 , with the lower part thereof bent downward and rearward. 
     As mentioned above, in the operation process of mating the second connector  60  with the first connector  10 , the second front engagement parts  63 A,  63 B slide on the guide surface  23   b  against the frictional force between the tip (lower end) of the second front engagement parts  63 A,  63 B and the guide surface  23   b  of the first front engagement parts  23 A,  23 B. Therefore, the second front engagement parts  63 A,  63 B are preferably highly rigid. 
     As illustrated in  FIG. 7B , the width W 5  of the second front engagement part  63 A in the anteroposterior direction may be larger than the width W 6  of the second front engagement part  63 A in the left and right direction. More specifically, in the base part of the second front engagement part  63 A, the width W 5  in the anteroposterior direction may be larger than the width W 6  in the left and right direction. This shape enables an increase in the rigidity of the second front engagement part  63 A. Consequently, in the operation process of mating the second connector  60  with the first connector  10 , the second front engagement part  63 A can be prevented from being deformed by the force received from the first front engagement part  23 A. Moreover, the width W 5  of the second front engagement part  63 A in the anteroposterior direction may be larger than the width W 7  (see  FIG. 6C ) of the terminal  11  in the left and right direction. This shape enables an increase in the rigidity of the second front engagement part  63 A. 
     The position of the second front engagement part  63 A in the left and right direction is close to the position of electric connection between the two connectors  10 ,  60 . Specifically, the second front engagement part  63 A is disposed so as to be closer to the center of the second connector  60  in the left and right direction compared with the second rear engagement part  64 A. In other words, the positions of two second front engagement parts  63 A,  63 B in the left and right direction are between the left and right second rear engagement parts  64 A,  64 B. Therefore, as illustrated in  FIG. 5 , in the mating state between the two connectors  10 ,  60 , the second front engagement parts  63 A,  63 B are respectively adjacent to the two terminals  11 . Specifically, the right second front engagement part  63 A is disposed further on the right of the right terminal  11 , while the left second front engagement part  63 B is disposed further on the left of the left terminal  11 . Because the second front engagement parts  63 A,  63 B are close to the positions of the terminals  11  in this way, the second front engagement parts  63 A,  63 B engage with the first front engagement parts  23 A,  23 B near the terminals  11  and the cable terminals  91 , enabling improved connection stability between the terminals  11  and the cable terminals  91 . Moreover, in the operation process of mating the second connector  60  with the first connector  10 , the relative displacement between the terminals  11  and the cable terminals  91  can be suppressed. 
     As illustrated in  FIGS. 2B and 5 , the front extension part  62  may have side walls  66  lowered from the right and left parts of the front extension part  62 . In the mating state between the first connector  10  and the second connector  60 , the upper part of the front wall  22  of the first connector  10  is disposed between the left and right side walls  66 . According to this structure, the displacement in the left and right direction of the first connector  10  and the second connector  60  can be reduced by the side walls  66  and the front wall  22 . 
     As illustrated in  FIG. 5 , the base parts of the second front engagement parts  63 A,  63 B may be connected to the side walls  66 . That is, a coupling part  62   e  may be formed between the base parts of the second front engagement parts  63 A,  63 B and the side walls  66 . This coupling part  62   e  can further increase the rigidity of the second front engagement parts  63 A,  63 B. In the example of the first connector  10 , because the second front engagement parts  63 A,  63 B are connected to the side walls  66  via the coupling part  62   e , the lengths of the left and right edges of the second front engagement parts  63 A,  63 B are different. That is, the coupling part  62   e  is formed further on the right of the second front engagement part  63 A formed on the right. As a result, the length of the right edge  63   d  of the second front engagement part  63 A is shorter than that of the left edge  63   c . In contrast, the coupling part  62   e  is formed further on the left of the second front engagement part  63 B formed on the left. As a result, the length of the left edge  63   d  of the second front engagement part  63 B is shorter than that of the right edge  63   c.    
     The cable terminal  91  is fitted in the holding hole  61   a  which is formed in the terminal holding part  61  of the second connector  60 . As illustrated in  FIG. 9A , the cable terminal  91  may have a core wire connection part  91   a  which holds the core wire of the cable  90  so as to be connected to the core wire. Moreover, the cable terminal  91  may have a terminal connection part  91   b  which is formed in front of a connection part  91   a  so as to sandwich the terminal  11  in the left and right direction. The terminal connection part  91   b  may have a first contact part  91   c  which contacts one side face of the terminal  11 , along with a second contact part  91   d  contacting the side face on the opposite side thereof. As illustrated in  FIG. 9B , the first contact part  91   c  may be formed in a substantially U shape so as to be elastically deformable. The first contact part  91   c  is pressed on the side face of the terminal  11  using the elastic force thereof. In contrast, the second contact part  91   d  may be plate shaped. In this way, because only one of the two contact parts  91   c ,  91   d  may be an elastically deformable shape, the width of the cable terminal  91  can be reduced compared with the case in which both the two contact parts  91   c ,  91   d  are made elastically deformable. Consequently, the second connector  60  and the first connector  10  can be miniaturized. 
     As described above, the connector assembly  1  includes: a first connector  10  which can be mounted on a circuit substrate  101 , and a second connector  60  which is capable of mating with the first connector  10  in the vertical direction and holds a cable terminal  91  provided at the end of a cable  90 , wherein the cable  90  is capable of being connected to the second connector  60  so as to extend rearward. The first connector  10  has first rear engagement parts  24 A,  24 B exposed towards the rear of the first connector  10 , along with first front engagement parts  23 A,  23 B exposed towards the front of the first connector  10 . A second connector  60  has second rear engagement parts  64 A,  64 B and second front engagement parts  63 A,  63 B. In the mating state between the first connector  10  and the second connector  60 , the second rear engagement parts  64 A,  64 B are disposed on the rear side of the first rear engagement parts  24 A,  24 B so as to engage with the first rear engagement parts  24 A,  24 B, while the second front engagement parts  63 A,  63 B are disposed on the front side of the first front engagement parts  23 A,  23 B so as to engage with the first front engagement parts  23 A,  23 B. 
     In this way, in the connector assembly  1 , because the second rear engagement parts  64 A,  64 B are respectively disposed on the rear side of the first rear engagement parts  24 A,  24 B so as to engage with the first rear engagement parts  24 A,  24 B, an operator can rotate the second connector  60  about the second rear engagement parts  64 A,  64 B. Moreover, because the second front engagement parts  63 A,  63 B are disposed on the front side of the first front engagement parts  23 A,  23 B, the direction D 2  of the force acting when the cable  90  is pulled is significantly different from the direction D 1  for disengaging the second front engagement parts  63 A,  63 B and the first front engagement parts  23 A,  23 B. As a result, two connectors  10 ,  60  can be effectively prevented from separating when the cable  90  is pulled. Moreover, in the first connector  10 , the first rear engagement parts  24 A,  24 B are exposed towards the rear of the first connector  10 . As a result, in the operation process of mating the second connector  60  with the first connector  10 , the operator can easily abut the second rear engagement parts  64 A,  64 B against the first rear engagement parts  24 A,  24 B, thereby improving the workability. 
     The connector assembly proposed in the present disclosure is not restricted to the example of the abovementioned connector assembly  1 . 
     For example, one or more of the engagement parts  23 A,  23 B,  24 A,  24 B,  63 A,  63 B,  64 A, and  64 A may be made of metal members. For example, the metal members may be installed at the rear ends of the side walls  21 R,  21 L of the first connector  10  and utilized as the first rear engagement parts  24 A,  24 B.