An assembled structure includes a power semiconductor device, a first insulating member, a heat sink and a fastening element. The power semiconductor device has a first perforation. The first insulating member includes a first opening and a second opening corresponding to the first perforation and a receiving portion between the first opening and a second opening. The fastening element includes a head portion and a body portion. The body portion is penetrated through the first opening, the receiving portion, the second opening and the first perforation such that the power semiconductor device is fastened onto the heat sink. The head portion is received in the receiving portion so as to isolate the head portion of the fastening element from adjacent electronic components