Board mounted electrical connector

[0001] This invention generally relates to the art of electrical connectors and, particularly, to a board mounted electrical connector such as in a board-to-board connector assembly.

[0002] Miniature board-to-board electrical connector assemblies are known in the art. Conventionally, a first or receptacle connector is mounted on a first printed circuit board, and a plug or second connector is mounted on a second printed circuit board. The plug connector is inserted into the receptacle connector, with the two printed circuit boards in generally parallel relationship.

[0003] For example, such board mounted electrical connectors are used in portable telephones, digital video cameras, digital still cameras or the like. In such small electronic devices, multiple circuit boards are disposed within a narrow confined space, and the connectors are used to provide electrical connection between the boards.

[0004] Conventionally, retention means are provided to hold the connectors in mated condition. Heretofore, a retention member having a first engaging portion is mounted on one of the connectors, and a second retention member having an engaging portion is mounted on the other connector. One of the engaging portions on one of the retention members comprises a protrusion which engages a flexible or spring engaging portion on the other retention member, thereby preventing inadvertent decoupling of the connectors. Examples of such retention means are shown in Japanese Patent Documents JP 2004-55306 A (which has a United States counterpart in U.S. Pat. No. 7,128,581); JP 2004-55463 A; JP 11-74024 A (which has a United States counterpart in U.S. Pat. No. 6,466,867); and Utility Model Application Laid-Open No. Hei 5-2385.

[0005] With conventional retention means, such as in Japanese Patent Document JP 2004-55306 A, the spring engaging portion on one of the one retention members is relatively long and extends in the mating or height direction of the connectors. This makes it difficult to miniaturize the connectors or reduce the connector heights. If the length of the spring engaging portion is reduced to reduce the height of the connector, a limitation is imposed on the elastic force of the spring engaging portion and causes a large force to act on the base of the spring, resulting in possible elastic deformation of the spring engaging portion. The elastic deformation makes it disadvantageously impossible to retain the connectors in mated condition.

[0006] In addition, the retention members often are used as ground terminals between a pair of circuit boards. If the spring engaging portion undergoes elastic deformation, the contact forces between the ground terminals is decreased, making the electrical connection unstable and reducing the reliability of the grounding function. The present invention is directed to solving this myriad of problems.

[0007] An object, therefore, of the invention is to provide a new and improved electrical connector assembly of the character described.

[0008] In the exemplary embodiment of the invention, a board-to-board electrical connector assembly includes a first connector having a dielectric housing for mounting on a first printed circuit board for receiving a plug portion of a second connector mounted on a second printed circuit board. The connectors are mateable in a mating direction. A plurality of first conductive terminals are mounted on the housing of the first connector along the receptacle for engaging a plurality of second conductive terminals mounted along the plug portion of the second connector. A first retention member is mounted on one of the connectors and is engageable with a second retention member on the other connector in the mating direction. The first retention member includes a flexible engaging portion which extends in a direction generally perpendicular to the mating direction. The second retention member includes a rigid engaging portion for engaging and flexing the flexible engaging portion to hold the connectors in mated condition.

[0009] According to one aspect of the invention, the first and second retention members are mounted on the first and second connectors, respectively. The flexible engaging portion of the first retention member is located inside the receptacle of the first connector. The rigid engaging portion of the second retention member is located outside the plug portion of the second connector.

[0010] According to another aspect of the invention, the flexible engaging portion of the first retention member is elongated and is cantilevered within a retention opening which receives the rigid engaging portion of the second retention member. As disclosed herein, the flexible engaging portion comprises a first flexible engaging portion, and a second flexible engaging portion is cantilevered within the retention opening and extends toward the first flexible engaging portion. The rigid engaging portion of the second retention member engages both flexible engaging portions.

[0011] According to a further aspect of the invention, the receptacle of the first connector and the plug portion of the second connector are generally rectangular, including major sides and minor ends. The terminals are spaced along the major sides, and the retention members are in pairs at the minor ends.

[0012] Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings.

[0024] Referring to the drawings in greater detail, and first to FIG. 1, the invention is embodied in a board-to-board electrical connector assembly, generally designated 12, which includes a first electrical connector, generally designated 14, mounted on a first printed circuit board 16 (FIG. 10), and a second connector, generally designated 18, mounted on a second printed circuit board 20 (FIG. 10). The first connector includes a dielectric housing, generally designated 22, which includes a pair of opposite side walls 22a and a pair of opposite end walls 22b which combine to define a generally rectangular receptacle, generally designated 24. The housing is generally rectangular, whereby side walls 22a are major sides walls and end walls 22b are minor end walls.

[0025] Referring to FIG. 2 in conjunction with FIG. 1, second connector 18 includes a dielectric housing, generally designated 26, which is generally rectangular and includes a pair of opposite side walls 26a and a pair of opposite end walls 26b which combine to define a rectangular structure which is insertable into rectangular receptacle 24 of first connector 14. The housings of the connectors may be molded of plastic material. Side walls 22a of the housing of the first connector mount a plurality of conductive terminals, generally designated 28, and side walls 26a of the housing of the second connector mount a plurality of conductive terminals, generally designated 30. Terminals 28 have tail portions 28a for connection, as by soldering, to appropriate circuit traces on printed circuit board 16. Terminals 30 have tail portions 30a for connection, as by soldering, to appropriate circuit traces on printed circuit board 20. Therefore, both connectors have two rows of interengaging or mating terminals.

[0026] Rectangular receptacle 24 in housing 22 of first connector 14 surrounds an elongated or rectangular platform, generally designated 32 (FIG. 1), which has opposite side surfaces 32a. Terminals 28 have contact portions 28b which project outwardly from side surfaces 32a. The connectors are mateable in a mating direction as indicated by the double-headed arrow “A” in FIG. 1. When the connectors are mated, platform 32 becomes inserted into an elongated recess, generally designated 34 (FIG. 2), in housing 26 of second connector 12. Terminals 30 have contact portions 30b at the inside surfaces of side walls 26a of housing 26 for engaging contact portions 28b of terminals 28.

[0027] Generally, the invention contemplates the provision of retaining means 36 for holding or retaining connectors 14 and 18 in their mated condition of FIG. 10. The retaining means is provided by a pair of first retention members, generally designated 38, on first connector 14 and a pair of second retention members, generally designated 40, on second connector 18. The first retention members 38 are mounted on end walls 22b of housing 22 of first connector 14. The retention members 40 are mounted on end walls 26b of housing 26 of second connector 18.

[0028] More particularly, referring to FIGS. 3-5 in conjunction with FIG. 1, each retention member 38 is generally U-shaped, as defined by a pair of leg portions 38a joined by a plate portion 38b. The leg portions have feet 38c for connection, as by soldering, to appropriate ground pads on printed circuit board 16, whereby the retention members 38 act as ground terminals for first connector 14. A pair of flexible engaging portions or springs 38d are formed out of a retention opening 38e of plate portion 38b. Retention members 38 may be stamped and formed of sheet metal (spring) material, and the engaging springs 38d are stamped and formed, out of retention opening 38e.

[0029] Referring specifically to FIG. 4, the double-headed arrow “A” represents the mating direction of connectors 14 and 18 as described above in relation to FIG. 1. It can be seen that the engaging springs 38d are narrow and elongated, having widths “W” and lengths “L”. The engaging springs extend toward each other from fixed bases 42 to adjacent distal ends 44. It can be seen that the elongated engaging springs extend in a direction generally perpendicular to mating direction “A”. Therefore, the lengths “L” of the engaging springs do not increase the height of connector 14. For purposes to be described hereinafter, retention opening 38e has an upper retention edge 46.

[0030] Referring to FIG. 5, retention members 38 are mounted within positioning recesses 48 inside the opposite end walls 22b of housing 22 of first connector 14. Therefore, engaging springs 38d are exposed at opposite ends of receptacle 24 of the first connector.

[0031] Referring to FIGS. 7-9 in conjunction with FIGS. 1 and 2, retention members 40 are mounted generally to the outsides of end walls 26b (FIG. 2) of housing 26 of second connector 18. Each retention member 40 is generally U-shaped to define a pair of end plate portions 40a and a cross plate portion 40b. End plates portions 40a have mounting leg portions 40c. A foot 40d projects outwardly from cross plate portion 40b for connection, as by soldering, to an appropriate ground trace on printed circuit board 20 (FIG. 10). Therefore, retention members 40 act as ground terminals for second connector 18. A rigid engaging portion or protrusion 40a projects outwardly from the cross plate portion 40b of each retention member 40. The retention members are mounted to the opposite end walls 26b of housing 26 by inserting the mounting leg portions 40c into a pair of mounting holes 50 in housing 26 in the direction of arrows “B” (FIG. 8). This positions cross plate portions 40b within a pair of positioning recesses 52 in the outer faces of end walls 26b of the housing. When so positioned, the rigid engaging protrusions 40e project outwardly from opposite ends of the second connector as seen best in FIG. 9.

[0032] FIG. 10 shows the first and second connectors 14 and 18, respectively, in mated condition, as having been mated in the mating direction indicated by double-headed arrow “A”. In this view, the engaging springs 38d of retention members 38 are flexible in the direction of double-headed arrow “C”. It can be understood that this flexing direction of the engaging springs is generally perpendicular to mating direction “A”. FIG. 10 shows the engaging protrusion 40e of one of the retention members 40 of connector 18 biasing or flexing one of the engaging springs 38d of one of the retention members 38 of connector 14 outwardly in the direction of arrow “B”. Consequently, the rigid engaging protrusion 40e enters the retention opening 38e of retention member 38 beneath the upper retention edge 46 of the opening. This retaining means 36 holds the connectors in their mated condition of FIG. 10.

[0033] It should be noted that the single engaging protrusion 40e of each retention member 40 engages and flexes both of the engaging springs 38d of the respective retention member 38. The pair of engaging springs provide an increased retention force without in any way increasing the overall height of the connector assembly. The two engaging springs also increase the contact forces between retention members 38 and 40 to positively, electrically couple the retention members which act as ground terminals for the two connectors.

[0034] It will be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.