SPEED CONTROLLER

PROBLEM TO BE SOLVED: To provide a light-weight speed controller having high cooling performance without increasing its scale. SOLUTION: The speed controller includes: a switching element 50; a drive control circuit 4; a first circuit board 31; a flexible sheet-like first heat sink 10 in which first and second insulating layers 11 and 12 are laminated on the front and back of the intermediate layer 10c of an excellent heat conductor and the first insulating layer 11 is brought into contact with the exposed surface 50f of the switching element 50; a casing; and a second heat sink 20 of ceramic material, which is provided correspondingly to the opening of the casing, has a contact surface 21 to be in contact with the second insulating layer 12 of the first heat sink 10, is in contact with the second insulating layer 12 in an area wider than the exposed surface 50f of the switching element 50 mounted on a first mounting surface F1, and radiates heat from the opening. COPYRIGHT: (C)2010,JPO&INPIT