The present disclosure relates to implantable neuromodulation devices and methods of fabrication, and in particular to a separable high density connectors for implantable neuromodulation devices. Particularly, aspects of the present disclosure are directed to a medical device comprising an electronics module and a header for connecting the electronics module to a lead assembly. The header includes: a housing that includes (i) a cavity having a central axis or plane and an internal surface, and (ii) an opening aligned with the central axis or plane of the cavity, an array of retractable contacts extending from the internal surface towards the central axis or plane of the cavity, and an array of connection terminals on the housing, where each connection terminal of the array of connection terminals is: (i) electrically connected to the electronics module, and (ii) electrically connectable to a retractable contact of the array of retractable contacts.