Various embodiments of an interposer for mounting a semiconductor die, as well as methods for forming the interposer, are disclosed. The interposer includes flexible solder pad elements that are formed from a core material of the interposer, such that the interposer may absorb thermally induced stresses and conform to warped or uneven surfaces. Embodiments of electronic device packages including a semiconductor die mounted to and electrically connected to the interposer, as well as methods for forming the electronic device packages, are also disclosed. In one electronic device package, the semiconductor die is electrically connected to the interposer with wire bonds attached to a routing layer of the interposer. In another electronic device package, the semiconductor die is electrically connected to the interposer by bonding the semiconductor die to the flexible solder pad elements of the interposer in a flip-chip configuration. A computer system incorporating an electronic device package with an interposer according to the present invention is also disclosed.