An electrical connector assembly includes a circuit board and an electrical connector mounted on the circuit board. The circuit board has a circuit board body having first and second surfaces and through-holes bored between the first and second surfaces. The circuit board has signal traces on internal layers of the circuit board that are generally parallel to the first and second surfaces. Portions of the circuit board body within the through-holes are etched away to expose portions of the signal traces beyond the circuit board body within the corresponding through-hole. The electrical connector includes a housing and signal terminals held by the housing. The signal terminals are received in respective through-holes of the circuit board and engage the corresponding signal traces.