Abstract: A compression-assembled device has similar pole pieces which are electrically insulated from one another by an outer insulation ring and, in operation, press against the opposing surfaces of a semiconductor device. The base of the insulation ring is secured to one of the pole pieces, and its other end, and the other pole piece have thin flexible flanges extending from their peripheries and the flanges are connected to one another to mechanically secure the assembly together. One of the flanges has several upturned lips on its circumference which are used to receive and center the other flange. A flexible insulation ring surrounds a semiconductor wafer and locates it between the pole pieces. The ring with the wafer is pressed into the outer insulation ring and thus prevents the wafer from moving within the pole pieces when the pole pieces are not under compression forces.