US Patent 6876213 Compliant actuator for IC test fixtures

An actuator for use in an IC package test fixture has a base element and a float. The float is attached to the base element with a gimbaled mount. At least one resilient element such as a compression spring biases the float away from the base element and against a retainer. The float has a presser surface for pressing against an IC package surface opposite the IC package contacts, to thereby force the contacts of the IC package against test contacts. The float's gimbaled mount in one embodiment provides up to two rotational degrees of freedom and one translational degree of freedom in the motion of the float. The resilient element provides a predetermined preload force at the presser surface.