Fixed welded structure of power transistor on printed circuit board

A fixing and welding structure for fixing and welding a power transistor on a printed circuit board comprises a power transistor pin, a single-side printed circuit board, a via hole for inserting the power transistor pin, and a bonding pad surrounding the via hole. The tip of the power transistor pin, exposed at the welding surface of the printed circuit board, and the middle part of the power transistor pin, disposed in the via hole of the printed circuit board, are angled at 90-100degrees. The section from the middle part to the upper part of the pin, which is close to the main body of the power transistor, and the middle part of the pin are angled at 90-100degrees. The tip of the power transistor pin is wrapped and fixedly connected by soldering tin with the bonding pad at the welding surface of the printed circuit board. The fixing and welding structure can adopt a common single-side printed circuit board which is low in cost and can improve the reliability of the welding spot of an electronic device and