Ultrasonic visualization of electrical trees

Abstract

In this paper, we report the use of 25 MHz ultrasonic waves to visualize electrical trees formed in insulating materials. In the experiment, the electrical trees generated in polymethylpentene ('TPX') were used to compare the structure characterized by ultrasonic waves with that by optical inspection. By scanning the transducer mechanically over the sample, the resulting structure of the tree was constructed and found to coincide with that inspected by the optical method.