A method of forming a temporary test structure for device fabrication is provided. The method allows for electrically testing conductive interconnects during controlled collapse chip connections (C4) fabrication and/or through-silicon vias (TSVs) during interposer fabrication. The method includes providing a substrate containing a plurality of electrically conductive interconnects extending vertically to top surface of the substrate. A temporary test structure is formed to connect the plurality of interconnects for electrical testing. Electrical testing is performed on the substrate by probing at different test locations on the temporary test structure. All or part of the temporary test structure is removed so as not to affect product performance. The temporary test structure can contain electrical test pads which provide a way to make temporary connections to small interconnect landings or features at extreme tight pitch to fan them out to testable pads sizes and pitches.