Aging prediction of quartz crystal units

Mechanisms are discussed which influence crystal unit stability with respect to time as well as their mathematical models. It is shown that it is possible to forecast aging over a longer period of time using extrapolation based on these models, if good correlation exists between the frequency changes measured over a short period of time and the calculated values. This method is used for high-stability components. It identifies out the dominant aging mechanism, which can be used for technological process control. The method of accelerated aging at higher temperatures can also be utilized for prediction purposes, especially for large-scale manufacturing with moderate technology. Several examples of the results obtained by these analyses are given.