Design DocumentMicrochip

Design and Manufacture of Low g-sensitivity QRM crystals

A technical review of Quad Relief Mount (QRM) resonator design improvements to achieve low g-sensitivity and push mechanical resonance above 2kHz using Kovar lead-frames.

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Overview

This document details the design and manufacturing refinements of Quad Relief Mount (QRM) quartz resonators aimed at minimizing acceleration sensitivity (g-sensitivity). It describes the transition from nickel-silver to stiffer Kovar lead-frames to increase mechanical resonance frequencies beyond 2kHz. The paper presents results from a Design of Experiments (DOE) investigating the impact of azimuthal mounting angles and contour diopters on performance. Findings indicate that a mounting angle of +20 degrees significantly improves g-sensitivity balance across all axes. Additionally, the document compares 0.320-inch and 0.390-inch diameter crystal blanks, noting improvements in resistance and quality factor with larger diameters while maintaining low g-sensitivity.

Use Cases

Precision timing in high-vibration aerospace environments
Low phase noise oscillator design for military communication
Stable frequency references in industrial equipment subject to mechanical shock
Avionics systems requiring high-reliability quartz resonators

Topics

QRM resonator

quartz crystal

g-sensitivity

acceleration sensitivity

mechanical resonance

Kovar lead-frame

azimuthal mounting angle

plano-convex resonator

vibration sensitivity

Referenced Parts

HP4396B

Hewlett-Packard

The method uses an HP4396B network/spectrum analyzer combined with a frequency source

QRM

Vectron International

This paper reviews the design and manufacture of an improved Quad Relief Mount (QRM) resonator.

HP4396B	Hewlett-Packard	The method uses an HP4396B network/spectrum analyzer combined with a frequency source
QRM	Vectron International	This paper reviews the design and manufacture of an improved Quad Relief Mount (QRM) resonator.