| 摘要 |
PURPOSE:To cancel a work for connecting a transistor with a diode by a lead wire by fixing a power transistor and a diode for protection connected to the former in series on the same conductive cooling member. CONSTITUTION:A control circuit 8 and an insulating plate 9 are connected on to the substrate 7 of a copper plate. A heat sink (cooling member) 10 is generally made of a metal plate having small thermal expansion, such as a molybdenum plate and is brazed with silver to the insulating plate 9. The power transistors Q1 and Q2 are connected directly with the diodes D5 and D6 for protection. Accordingly, the heat generated at the transistors Q1 and Q2 and the diodes D5 and D6 is conducted efficiently from the heat sink 10 to the substrate 7 through the insulating plate 9 and, therefore, the heating can be made very small. Since the power transistors Q1 and Q2 and the diodes D5 and D6 for protection thereof are fixed on the same conductive cooling member 10, the work for connection can be dispensed with, and in addition, the heating can be made small and high reliability is obtained since the connection can be made completely. |
