A surface mounted power transistor is provided with a heat sink by positioning a mounting plate of a heat sink between the power transistor and a solder pad on the circuit board. The mounting plate of the heat sink is provided with a plurality of openings through which the solder of the solder pad flows during the solder reflow process so that the mounting plate is securely adhered between the power transistor and the circuit board. The mounting plate of the heat sink is connected thermally to an extension member which extends generally perpendicular to the mounting plate, the extension member in turn being connected to a heat dissipation surface which may be one or several fins.