An RFID device interposer has folded ends that bring conductive lead end portions of conductive leads of the interposer to an underside of the interposer. The central conductive lead portions of the conductive leads remain on an upper surface of a dielectric substrate of the interposer. The folded ends of the interposer may be held together with an adhesive, or with thermal compression bonding. The interposer may also have an additional conductive material layer on an underside of the dielectric substrate. The conductive material layer may be capacitively coupled to the conductive leads of the interposer. The interposer may be tuned by varying the pressure used to secure the folded ends. This may be used to provide a better impedance match between a chip of the interposer, and the conductive leads and an antenna to which the interposer is coupled.