Editing Crystal oscillator (section)

=== Mechanical damage ===
Crystals are sensitive to [[shock (mechanics)|shock]]. The mechanical stress causes a short-term change in the oscillator frequency due to the stress-sensitivity of the crystal, and can introduce a permanent change of frequency due to shock-induced changes of mounting and internal stresses (if the elastic limits of the mechanical parts are exceeded), desorption of contamination from the crystal surfaces, or change in parameters of the oscillator circuit. High magnitudes of shocks may tear the crystals off their mountings (especially in the case of large low-frequency crystals suspended on thin wires), or cause cracking of the crystal. Crystals free of surface imperfections are highly shock-resistant; [[chemical polishing]] can produce crystals able to survive tens of thousands of [[G-force|g]].<ref>[http://www.ieee-uffc.org/frequency_control/teaching.asp?vig=vigaccel Frequency Control|Teaching Resources] {{webarchive|url=https://web.archive.org/web/20100706000011/http://www.ieee-uffc.org/frequency_control/teaching.asp?vig=vigaccel |date=2010-07-06 }}. Ieee-uffc.org. Retrieved on 2010-02-08.</ref>

Crystals have no inherent failure mechanisms; some have operated in devices for decades. Failures may be, however, introduced by faults in bonding, leaky enclosures, corrosion, frequency shift by aging, breaking the crystal by too high mechanical shock, or radiation-induced damage when non-[[swept quartz]] is used.<ref>[http://www.am1.us/Papers/U11625%20VIG-TUTORIAL.PDF Quartz crystal resonators and oscillators for frequency control and timing applications]: a tutorial by John R. Vig, U.S. Army Communications-Electronics Command</ref> Crystals can be also damaged by overdriving.