Abstract: A wafer probe head assembly for providing signal paths between an integrated circuit (IC) tester and input/output, power and ground pads on the surfaces of ICs formed on a wafer to be tested includes an adapter board and a probe card assembly including a space transformer and a contactor carrying substrate having a substantially planar bottom surface with printed or plated circuit traces formed thereon and a plurality of contactors plated to or photo-lithographically formed on the traces and arranged to simultaneously ohmically engage the contact pads of one or more ICs on a wafer under test. The contactors may include resilient supporting structures attached to or integrated with the signal carrying circuit traces. The probe card assembly may also include one or more substrate layers with the circuit traces and vias formed on and/or within the substrate layers to facilitate connection of the tester to the contactors.