Epoxy seal packages are widely used for high volume and low cost SMD crystals.  The frequency stability performance is not as good as those seam weld and resistance weld parts.

Cold Weld

      Cold weld sealing is a precision performance package that is somewhat more expensive, but sealing process introduces virtually no contamination, resulting in superior resonator frequency stability and electrical performance.

All-Quartz Package

       An all-quartz packaging technique is used in producing a surface mount resonator having very low profile and very high shock resistance. The availability of this type of sealing package is rather limited.

Detailed Frequency Temperature Curve for Fundamental Mode "AT-cut" Crystals

                     

      The above curves represent the frequency vs. temperature characteristics of a series of AT-cut crystals.  Each numbered curve is accomplished by controlling the angle of the crystal cut in reference to the angle (35° 15' ) and each curve is one minute of change.  LTP indicates the Lower Temperature Turnover Point;