Abstract: A spring steel bayonet type retainer for securing encapsulated semiconductor devices to circuit boards either directly or through an intermediate heat dissipator. The retainer comprises a spring steel body bent approximately centrally and at approximately right angles. At least one portion is slotted to define outboard spring fingers and inboard bayonet type arms which extend through aligned holes in the device and the circuit board. The noncoplanar portions provide clamping forces on the main body of the encapsulated semiconductor device and may be provided with laterally outwardly extending ears to fit closely within the confines of a heat dissipator device to prevent relative rotation therebetween.