Board-to-board electrical connector assembly

An electrical connector assembly used for electrically connecting two separate printed circuit boards comprising:

• a first connector defining a first housing for receiving a plurality of first contacts, the first housing defining an island portion having two opposite first mating surfaces;
• a second connector defining a second housing for receiving a plurality of second contacts, the second housing defining a recess having two opposite second mating surfaces;
• wherein,
• the first housing defines a protruding block on each of the two first mating surfaces respectively and the second housing defines a sunken slot on each of the two second mating surfaces respectively, each sunken slot being matching with the corresponding protruding block.

An electrical connector assembly comprising:

• a first connector defining a first insulative housing defining a first cavity with therein an center island along a lengthwise direction;
• a plurality of first contacts disposed on two sides of the center island;
• a second connector defining a second insulative housing, received in the first cavity, and defined with a second cavity, along said lengthwise direction, receiving the center island;
• a plurality of second contacts disposed on two opposite inner side walls of the second housing and engaged with the corresponding first contacts, respectively;
• and
• interengaging means being formed around lengthwise end sections, along said lengthwise direction, of both said first and second housings, said interengaging means including at least one protrusion formed on the corresponding end section of one of said first housing and said second housing, and at least one recess formed in the corresponding end section of the other of said first housing and said second housing and receiving said protrusion therein for providing retention between the first housing and the second housing.