Abstract
In regard to a noise from encapsulation for power semiconductor devices, we investigated the vibration action of a flange which is the main cause of noise occurrence. Furthermore, we studied the influence of the vibration on the reliability of the power semiconductor encapsulation, and looked at a plan to reduce the vibration. We found that Lorentz power caused the flange to vibrate from the magnetic flux change which accompanies switching of a main current. The flange vibrated with a maximum amplitude of 8μ with 2.5kHz (current: 600A). The vibration amplitude of the encapsulated semiconductor device was estimated as about 60μm. At this time, the largest stress occurrence was 12kg/mm2. The value was 1/2 or less that the limit fatigue of the flange composed of 42 alloy. We concluded there would be no problem regarding fatigue destruction of the flange.
Furthermore, when a vibration absorber was fixed between the flange and the insulator, the vibration of the flange could be reduced to about 1/10. This measure was considered to contribute to low noise operation.
