A spring element, for securing components of an electronic control device, is essentially U-shaped, with a bridge portion (16), which rests on an end (11A) of a cooling fin (11) mounted perpendicularly on a printed circuit board (13), and a pair of depending spring legs (17, 18), one of which presses against a side face (11C) of the cooling fin (11) and the other of which presses a power component (14) against a major surface (11B) of the cooling fin (11). Preferably, the spring element (15, 15A) is formed with a pair of slots (23, 24) which facilitate engagement by a pair of tongs (25, 26) of an automatic mounting device. The tongs can spread open the spring element and position it around the cooling fin (11) and power component (14) without exerting any harmful shear forces on the fin or component. Preferably, each spring leg has a convex central section, below the slot, and a concave bottom or terminal end. Optionally, the inner surface of the terminal end (21A, 22A) is formed with a claw or tooth (27, 28) for better holding.