Abstract: The invention provides a fastener assembly suitable for joining a first element such as a circuit board to a second element such as a casing or another circuit board. The fastener assembly includes a first component which has a pin and a second component which includes a cavity for receiving at least part of the pin. In one aspect, at least part of the second component capable of being received within a bore in the first element. Either the first component or the second component is made of material which can change from a first shape to a second shape at a particular temperature. The pin of the first component is adapted to be locked into the cavity of the second component when the second shape is attained, through interaction of the material with the cavity, without deformation of the pin.