An interposer for electrically engaging semiconductor components having contact balls is provided. In a testing embodiment, the interposer configures a test socket for testing semiconductor components with different configurations of contact balls. In an assembly embodiment, the interposer can be used in the fabrication of an electronic assembly, to configure a substrate of the assembly for use with semiconductor components having different configurations of contact balls. The interposer includes a base having external contacts, an interconnect having contacts for electrically engaging the contact balls on the component, and an alignment member for aligning the component to the interconnect. The interconnect contacts can be made using semiconductor fabrication techniques for accommodating small, closely spaced contact balls on the components. In addition, conductors on the base and interconnect can have a “fan out” configuration, which permits contacts on the test socket, or substrate, to have a larger size and pitch than the contact balls on the component.