A probe card assembly for testing circuit boards is disclosed. In some embodiments, the assembly includes the following: a multi-layered dielectric plate aligned with an integrated circuit, the integrated circuit having on its surface a first plurality of electrical contacts arranged in a pattern, the dielectric plate having arrayed upon its surface a second plurality of electrical contacts arranged in a pattern substantially matching the first plurality of electrical contacts; a nanotube interposer interposed between the dielectric plate and the integrated circuit, the nanotube interposer having compliant carbon nanotubes that are arranged to match the pattern of electrical contacts on the integrated circuit and the dielectric plate; and a plurality of vertical probes arrayed upon the nanotube interposer and joined with the nanotubes, the vertical probes making electrical contact with the first plurality of electrical contacts and the second plurality of electrical contacts via the nanotubes.