A press-fit circuit board connector comprising: a housing having a mating end and a mounting end opposite the mating end configured to be mounted to a host circuit board, the housing having a cavity between the mating end and the mounting end; a mating contact assembly having a mating contact holder including a plurality of contact channels and a plurality of mating contacts received in corresponding contact channels, the mating contacts having mating pins at mating ends of the mating contacts, the mating contact assembly received in the cavity of the housing positioning the mating pins at the mating end to define a pin mating interface for mating with an electrical connector; and a mounting contact assembly having an interposer circuit board and a plurality of mounting contacts electrically connected to the interposer circuit board at corresponding circuits of the interposer circuit board, the mating contacts being electrically connected to corresponding circuits of the interposer circuit board to electrically connect the mating contacts and the mounting contacts via the interposer circuit board, the mounting contacts having press-fit mounting pins at mounting ends of the mounting contacts, the interposer circuit board received in the cavity with the press-fit mounting pins of the mounting contacts arranged at the mounting end for press-fit termination to the host circuit board, characterised in that the interposer circuit board includes a rigid upper circuit board, a rigid lower circuit board and a flexible circuit (212, 222) between the upper circuit board and the lower circuit board, the mounting contacts being electrically connected to the lower circuit board, the mating contacts being electrically connected to the upper circuit board, the flexible circuit (212, 222) electrically connecting the mating contacts electrically connected to the upper circuit board with corresponding mounting contacts electrically connected to the lower circuit board. a housing having a mating end and a mounting end opposite the mating end configured to be mounted to a host circuit board, the housing having a cavity between the mating end and the mounting end; a mating contact assembly having a mating contact holder including a plurality of contact channels and a plurality of mating contacts received in corresponding contact channels, the mating contacts having mating pins at mating ends of the mating contacts, the mating contact assembly received in the cavity of the housing positioning the mating pins at the mating end to define a pin mating interface for mating with an electrical connector; and a mounting contact assembly having an interposer circuit board and a plurality of mounting contacts electrically connected to the interposer circuit board at corresponding circuits of the interposer circuit board, the mating contacts being electrically connected to corresponding circuits of the interposer circuit board to electrically connect the mating contacts and the mounting contacts via the interposer circuit board, the mounting contacts having press-fit mounting pins at mounting ends of the mounting contacts, the interposer circuit board received in the cavity with the press-fit mounting pins of the mounting contacts arranged at the mounting end for press-fit termination to the host circuit board, characterised in that the interposer circuit board includes a rigid upper circuit board, a rigid lower circuit board and a flexible circuit (212, 222) between the upper circuit board and the lower circuit board, the mounting contacts being electrically connected to the lower circuit board, the mating contacts being electrically connected to the upper circuit board, the flexible circuit (212, 222) electrically connecting the mating contacts electrically connected to the upper circuit board with corresponding mounting contacts electrically connected to the lower circuit board.