AGING CHARACTERISTICS OF QUARTZ CRYSTAL RESONATORS.
Final technical rept., 15 Feb 61-15 Feb 63,
GEORGIA INST OF TECH ATLANTA ENGINEERING EXPERIMENT STATION
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Over three hundred AT-cut quartz resonators of 16 Mc fundamental frequency were meticulously fabricated, stored at 85 C and measured for frequency stability in the fundamental, third and fifth modes over periods of 3 to 15 months. Controlled variables introduced were types of quartz, plating metal, bonding cement, and mounting envelope. Accuracy of measurements was a few parts in 10 to the 9th power. Observations made previously with regard to aging being greater and more erratic at the fundamental than at the overtone modes were confirmed. The better units, coated with single layer electrodes of aluminum or gold changed frequency 2 parts in 10 to the 8th power per month and those coated with bimetal layers of Al Au changed only slightly more. Resonators plated with Al Al exhibited changes several times greater. Bilayer electrodes of all types, in general, induced greater frequency changes than single layer electrodes and greater susceptibility to frequency shifts due to inadvertent temperature cycling oven failure and oven opening. Author