Compact electrical connector

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.