Polypropylene membrane decreases contact wear of piezoelectric transformer with heat transfer structure

Abstract

A new design is presented to decrease the contact wear between a piezoelectric transformer and its heat transfer structure by inserting a layer of polypropylene membrane between them. Without significant degradation of performance, the wear problem is well suppressed with notable extension of working life. Compared with the former wear rate of 2.72% per day on the electrodes in the first 2.5 working days, the wear rate with polypropylene membrane is decreased to only 0.03% per day within an accumulated working time of 110 days. Moreover, with the insulating layer, structure design and package become more flexible as the metal electrodes and radiator are isolated.

Vertically aligned carbon nanotube arrays as thermal interface material for vibrational structure of piezoelectric transformer

“…It is greatly improved when HTS is applied to PT device. When the PP membrane is employed as a TIM and the power density approaches 100 W cm −3 , the temperature rise comes to about 11 K with an efficiency of 87%, which was similar to Ju's results [24]. It is even better when CNT arrays served as TIM in the device.…”

“…When the PT separates from the CNT arrays TIM after operating continuously for about 120 days, the surface is still with metallic luster and the silver electrode is well covered without significant wearing damage when compared with the initial state. For comparison purpose, previous work of the wearing problem with PP membrane also showed in figure 9(b) [24]. As can be seen, for the PT with PP membrane, stains due to wearing started to develop in the middle region of PZT plate after working for 110 days.…”

“…Three thermal management configurations were designed to characterize the difference of temperature rise and efficiency in PT device: (1) free vibration without HTS, (2) the PP membrane as a TIM between PT and Si substrate, (3) the CNT arrays as TIMs between PT and Si substrate. According to Ju's solution [24], PP membrane can reduced the fretting and improve the working life of PT, thus we take it for a comparison here. Since the as-grown CNT array sample was synthesized on Si substrate, the PZT-PP membrane assembly also had a Si substrate in configuration (2).…”

“…However, in this case, the rigid contact of two surfaces with relative vibration or sliding leads to a series of disadvantages, such as the poor thermal contact at the rough surface and the noticeable fretting and wearing induced by friction. Ju developed a structure using polypropylene (PP) membrane tape as thermal interface material to fill in the rough surface and to reduce the fretting and wearing [24]. However, polymers like PP are known as poor thermal conductor, and their thermal conductivity is generally at the order of 0.1 W/m-K, which is much lower than general TIMs.…”