A system for fixing a substrate with a heat transferring device in an assembled orientation; the system comprising: a substantially rod-shaped positioning member having a length generally symmetrically oriented about an axis and a generally constant lateral expanse substantially perpendicular with said axis substantially along said length; said positioning member interferingly fitting within at least one of a first aperture in said substrate and a second aperture in said heat transferring device to maintain a predetermined separation between said substrate and said heat transferring device in said assembled orientation.