Aging

     Crystal resonance frequency and resonance resistance are over the duration of the change, which is called aging, people are most concerned about is the resonant frequency changes over time.
      For AT-cut crystal, in the early use of crystals, mainly due to component aging effects of internal stress relief, increased frequency to change direction, and the late effects of electrode films adsorbed by its frequency logarithmically to reduce the direction changes with time increasing the amount of change is gradually decreased (Figure 4). To reduce the rate of aging factory, manufacturers, most of the product was pre-aging treatment.
  Aging indicators generally provide aging product level, but it is not clear the test conditions, this "level" is planned sampling through the production obtained. Some individual crystal elements may be worse than the predetermined level, which is permissible.