A microelectronic test device comprising an organic substrate, a probe holder, and an interposer disposed between the organic substrate and the probe holder, wherein the interposer has a coefficient of thermal expansion that is less than a coefficient of thermal expansion of the organic substrate. The interposer may effectively decouple the organic substrate from probes in the probe holder, which may substantially reduce or eliminate probe misalignment due to the coefficient of thermal expansion mismatch between the organic substrate and other components of the microelectronic test device and to provide require stiffness to the organic substrate.