Heat sinks with staked solderable studs

Heat sink apparatus fastenable with a packaged electronic device for wave-soldered mounting on a printed-circuit board, comprising a metal heat sink having cooling portions remote from a portion adapted to be mated with a packaged electronic device, and relatively thin sheet-metal mounting studs each having a substantially flat and relatively broad-area portion abutted and staked with surfaces of said cooling portions which face inwardly of the exterior of said cooling portions and each having an elongated integral solderable tab portion depending therefrom in position to project through accomodating openings in a printed-circuit board and to bond with solder which locks the tab portion with the board and thereby holds the heat sink in place atop the board, said mounting studs each having a doubly non-symmetrical aperture therethrough into which material of an abutted cooling portion of said heat sink has been cold flowed by punching, said aperture being oriented substantially centrally of said broad-area portion and having a polygonal outline imparting an angular non-symmetry to it about its center and being non-symmetrical in the transverse direction by being flared outwardly in said transverse direction away from the side of said broad-area portion which abuts said heat sink, and said tab portion of each of said studs being laterally displaced slightly from said broad-area portion to form a bend at the lower edges thereof disposed for underlying contact with lower edges of said cooling portions of said heat sink and otherwise projecting downwardly substantially parallel with said broad-area portion, said bend augmenting angular locking effects and serving as a spacer between said lower edges of said cooling portions and the top of the printed-circuit board.