Flexible semi-hermetic implantable medical device (IMD) structure, including a flexible device body, at least one flexible lead and at least one respective transition unit, for respectively coupling each flexible lead to the flexible device body, the flexible device body including a plurality of hermetically sealed components, at least one electrical cable harness and an external flexible polymer structure, each one of the hermetically sealed components including at least one hermetically sealed electrical connection and at least some of the hermetically sealed components including at least one separation dome, the electrical cable harness for electrically and mechanically coupling the plurality of hermetically sealed components together and the external flexible polymer structure for encapsulating the hermetically sealed components, the electrical cable harness and the respective transition unit.