A probe head for testing the properties of a semiconducting device (10) under test including a dielectric film (24) supporting at least one semiconducting device (10) under test with a support frame (26) tautly supporting the dielectric film (24). A first support (40) positions a first probe (28) for electrically contacting a first side (16) of the semiconducting device (10) under test and a second support (34), having a actuator to move a second probe (30) between a first position (P1) and a second position (P2), positions second probe (30) with the second position (P2) being for electrically contacting an opposing second side (18) of the semiconductor device under test.