Mechanical fixture for holding electronic devices under test showing adjustments in multiple degrees of freedom

A fixture to hold an electronic substrate having probe areas on a top surface. The top surface of the electronic substrate is left open to provide a maximum area to couple interconnect wires for a device under test. In addition, a bottom surface of the substrate is left open to provide a maximum area to couple with a probe card in one embodiment, or a test head in another embodiment. This open bottom and open top minimize the mechanical interference with electrical connections. The substrate is planarized to a frame by one or more clamps that are attached to the frame. The clamps provide adjustment of the pressure down on the substrate in a Z-axis direction which is normal to the top surface of the substrate for providing a good connection with a planar card. In addition, the clamps provide adjustment in the an X-Y plane parallel to the frame and rotational correction about the Z-axis.