US Patent 7544102 Plunger-type contact unit

A contact unit which enables reduction of an interval between contacts to be inserted into a through hole formed in a plate. A contact of an IC socket is formed so that a first flange portion is disposed in a first gap between an upper plate and an intermediate plate while an outside diameter of the first flange portion is set larger than a diameter of an upper through hole of the upper plate and that a second flange portion is disposed in a second gap between an intermediate plate and a lower plate while an outside diameter of a second flange portion is set larger than a diameter of a lower through hole of the lower plate.