A device for power factor correction can include a converter housing having an inner surface; a first converter substrate mounted on the inner surface of the converter housing; a second converter substrate mounted on another surface of first converter housing opposite to the inner surface; and a housing cover covering the first converter substrate and coupled to an upper surface of the converter housing, in which the second converter substrate includes a first surface having a first region including a source pad, and a second region including a drain pad spaced apart from the source pad, the source pad including a source pad extension portion extending into the second region; and a second surface including a heat dissipation pad for communicating heat from the source and drain pads to an outside of the device, in which the first region of the second converter substrate overlaps with the another surface of first converter housing, and the second region of the second converter substrate faces the housing cover without overlapping with the first converter substrate.