Compact electrical connector

1. An electrical connection device comprising a receptacle connector, the receptacle connector being disposed at a lower side of a circuit board and comprising:

a first housing having:

a first body;

an accommodating groove locating in the front of the first body and opening upwards;

a plurality of first terminal grooves provided in the rear of the first body, intervally arranged, and in communication with the accommodating groove, each of the first terminal grooves being concavely provided from up to down in the first body and the two adjacent first terminals being spaced by a side wall; and

a plurality of securing portions extending rearwards from the first body; and

a plurality of first terminals correspondingly disposed into the first terminal grooves from up to down, respectively, each of the first terminal has:

a first fixing portion uprightly secured in the first terminal groove;

an U-shaped resilient arm folded forwards and then extending upwards from a lower end of the first fixing portion;

a first contact portion formed at a distal end of the U-shaped resilient arm and extending into the accommodating groove and having a distal end as a free end; and

a soldering portion extending upwards from an upper end of the first fixing portion and soldered to the circuit board from down to up.

2. The electrical connection device according to claim 1 , wherein at least one of the securing portions is extended rearwards with a supporting block from a rear end thereof.

3. The electrical connection device according to claim 2 , wherein a convex post extends upwards from a top surface of each of the side walls, and the free end of each of the first terminals is located between the two adjacent convex posts.

4. The electrical connection device according to claim 3 , wherein the convex post has a top surface higher than a bottom surface of the circuit board.

5. The electrical connection device according to claim 4 , wherein each of the first terminals further has an extending portion foldedly extending rearwards from an upper end of the first fixing portion, and the soldering portion extends upwards from a distal end of the extending portion.

6. The electrical connection device according to claim 5 , wherein the rear wall of the first body is located under the lower side of the circuit board, and the first body is provided with a plurality of retaining grooves opening upwards, the retaining grooves are correspondingly provided in the securing portions, respectively, and the electrical connection device further comprises a plurality of retaining tabs which correspondingly pass through the retaining grooves from down to up, respectively, and are secured to the circuit board.

7. The electrical connection device according to claim 6 , wherein each of the first terminal grooves is defined by a rear wall and a pair of side walls together, the pair of side walls are concaved inwards at positions respectively adjacent the rear wall so that each of the first terminal grooves has an outward expanding portion extending toward the pair of side walls at a position adjacent the rear wall, the first fixing portion of each of the first terminals is positioned at the outward expanding portion, and a rear side of the first fixing portion abuts against the rear wall, the first resilient arm is located in the first terminal groove, the extending portion foldedly extends rearwards outside the first terminal groove to above the rear wall.

8. The electrical connection device according to claim 4 , further comprising an interposer connector, the interposer connector comprises a second housing and a plurality of second terminals, the second housing has a longitudinal mating portion engaging with the accommodating groove of the receptacle connector, each of the second terminals is disposed in the second housing and has an interposer portion with a plate-like shape supported by the longitudinal mating portion, wherein the longitudinal mating portion is inserted into the accommodating groove from up to down so that the interposer portion with the plate-like shape is electrically connected with the first contact portion of respective one of the first terminals extending into the accommodating groove.