Electrical connector with improved impedance continuity

An electrical connector, comprising:

• a middle board defining a plurality of receiving holes;
• a first insulative housing mounted on one side of the middle board and defining a first receiving room for receiving a first mating connector;
• a plurality of contacts mounted on the first insulative housing, the contacts comprising a plurality of signal contacts and a plurality of grounding contacts, each of the signal contacts and the grounding contacts comprising a first mating portion received in the first receiving room, a second mating portion opposite to the first mating portion, and a middle portion between the first and the second mating portions, the middle portions extending beyond the first insulative housing and received in the receiving holes of the middle board, each of the middle portions of the signal contacts being solid, and each of the middle portions of the grounding contacts having a through hole and having an outer profile wider than that of the middle portion of the signal contact;
• and
• a second insulative housing on the other side of the middle board opposite the first insulative housing, the second insulative housing comprising a second receiving room for receiving a second mating connector;
• wherein the middle portions of the signal contacts and the middle portions of the grounding contacts are disposed at a same level;
• and
• wherein the middle board is sandwiched between the first insulative housing and the second insulative housing, the middle portions of the signal contacts and the middle portions of the grounding contacts being receiving in the receiving holes;
• wherein the receiving holes for receiving the middle portions of the signal contacts are free of any conductive material so as to be insulated from the signal contacts, and the receiving holes for receiving the middle portions of the grounding contacts are coated with conductive material to electrically connect with the grounding contacts;
• wherein the middle portions of the signal contacts are thinner than the first and the second mating portions of the signal contacts;
• and
• wherein the first mating portions of the signal contacts are shorter than the first mating portions of the grounding contacts, and the second mating portions of the signal contacts are shorter than the second mating portions of the grounding contacts.