GB/T 38447-2020 in English

Scope of application and technical characteristics

This standard is applicable to the fatigue performance evaluation of MEMS structures in a resonant state, focusing on solving the long-term reliability problem of micron-scale structures. By precisely controlling the vibration amplitude (±3% accuracy) and frequency stability, an accelerated aging test equivalent to actual working conditions is achieved.

Silicon-based MEMS actuator test example

An electrostatically driven micromirror adopts the integrated detection scheme in Appendix A, at a resonant frequency of 39kHz:

• Automatic gain control is used to keep the amplitude fluctuation less than 2%
• Step stress loading is used (10MPa per level)
• Humidity is controlled at 50%±1% to avoid environmental interference

The test data is consistent with the prediction of Paris' law, verifying the applicability of the crack growth theory.

Compared with the traditional metal fatigue test (GB/T 24176), the innovations of this standard are:

1. Introducing resonance mode coupling to solve the problem of insufficient microstructure driving force
2. Using online frequency tracking to compensate for the influence of temperature drift
3. Establishing the Weibull-Paris composite model of silicon material to explain the high cycle fatigue phenomenon