Patent ID: 8794889

Claim:
A floating captive screw capable of being mounted in a preformed first aperture of a first panel, being a microcircuit heat sink flange, for attachment to a second aperture in a second panel, being a PC board, said captive screw comprising: a ferrule having a generally cylindrical portion having an inner bore with an inner annular ring on the interior surface of said bore, said ferrule being adapted to be received into said first aperture of said first panel wherein said ferrule has a plurality of securing knurls engaging said first panel; a screw having a head, a shank and a threaded portion at the end of the shank opposite the head, said shank and said threaded portion being adapted to pass through said ferrule bore; wherein said inner annular ring is formed by plastic deformation of material during assembly wherein pressure is applied uniformly on the generally cylindrical exterior portion of the ferrule to form said inner annular ring, wherein said ferrule has a collapsed annular circumferential groove which allowed the formation of the ring; a collar being fixed on said shank at a position between said inner annular ring of said ferrule bore and the screw threaded portion after said screw shank and said threaded portion have passed through the ferrule bore, wherein said collar limits penetration of the screw when engaging said second panel and wherein said collar captivates said screw to said ferrule; a spring positioned over said screw shank between said head and said inner annular ring; and wherein said collar is formed by being rolled onto said screw shank under the ferrule to limit penetration of the screw threads in the second panel so that the first panel floats on the spring.