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by John R. Vig* and Thrygve R. Meeker**

*U.S. Army Communications-Electronics Command
Research, Development & Engineering Center
Att: AMSEL-RD-C2-CS
Fort Monmouth, NJ 07703-5603

** 2956 Lindberg Ave.,
Allentown, PA 18103

TABLE OF CONTENTS

Abstract.

Introduction.

The Impacts of Aging.

Aging Characteristics.

Includes:
Figure 1 - Typical Aging Behaviors.
Figure 2 - Typical Aging Behavior, Including an Interruption (frequency change in parts in 109 vs. time in days).

Aging Mechanisms.

Includes:
- Contamination Transfer Effects: Adsorption, Desorption, Oxidation and Permeation.
- Figure 3 - The Oxidation of Nickel vs. Time. Electrode Effects.
- Strain/Stress in the Resonator.
- Diffusion Effects.
- Table I
- Changes in the Quartz.
- Circuit Aging and Other Electrical Aging.

Includes:
- Figure 4 - The Effect of Aging Inerruption
- Frequency and Overtone Dependence of Aging.
- Drive Level Dependence of Aging.
- The Effects of Aging Interruptions.
- Dependence of Aging on Material and Mode Type.
- Dependence of Aging on Resonator Material.
- Dependence of Aging on Mode Type.
- Table II
- Low-aging Oscillators: The State of the Art, Present and Future.

Includes:
- Multiple Aging Mechanism Pitfall.
- Brief Review of the Theory of Rate Processes.
- A Log-time Law of Chemisorption, Oxidation, and Stress Relief.
- Implication of the Log-time Aging Law.
- Figure 5 - Aging Model Showing Log-Time Dependance Aging with Two Simultaneous Log-time Mechanisms.
- Figure 6 - Aging Model With Two Simple Log-time Mechanisms. Isothermal Aging.
- Figure 7 - Schematic Plot of Isothermal Aging at two Temperatures Thermal Step Stress (Differential Thermal Analysis).
- Figure 8 - Schematic Plot of Thermal Step Stress Aging Other Aging Characterization Techniques.

References.

The aging of quartz crystal resonators, filters and oscillators is reviewed, including the topics of: the impacts of aging, typical aging characteristics, aging specifications, aging mechanisms, temperature dependence of aging, frequency and overtone dependence of aging, drive level dependence of aging, the effects of aging interruptions, the dependence of aging on material and mode type, the state-of-the-art in low-aging oscillators, and aging acceleration effects. The aging mechanisms discussed include: contamination transfer effects, stress effects, electrode effects, diffusion effects, changes in the quartz material, and circuit and other electrical changes. Isothermal and thermal step stress aging acceleration methods are also reviewed.

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