A receptacle connector includes an insulating housing including a base and a mating tongue extending from the base and the mating tongue defining a thicken step portion at a root near to the base, two rows of contacts with contacting section exposing to opposite surfaces of the mating tongue in front of the step portion and tail sections extending out of the base, and a pair of separate metallic collars respectively disposed upon the opposite surface of the step portion. Two opposite ends of each metallic collar are embedded in the step portion of the insulating housing via an inserting mold process.