Quartz Crystal Resonator Cutting Angles for Wide-Temperature Stability

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Solution Overview

Problem

Conventional quartz crystal resonators, such as those cut using the AT-cut method, fail to maintain a stable vibration frequency deviation within the required range of ±20 ppm across a wide operating temperature range from -40 °C to 125 °C, especially in extreme environments.

Innovation Solution

A novel cutting method for quartz crystal resonators involves rotating a quartz bar with perpendicular light, electrical, and mechanical axes to form specific angles between the major face and these axes, resulting in a quartz crystal with a vibration frequency deviation inflection point between 30 °C to 45 °C, ensuring a ±20 ppm deviation across the specified temperature range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional AT-cut method is used to cut quartz crystal, then the manufacturing process is simple, but the vibration frequency deviation exceeds ±20 ppm in extreme temperature environments (-40°C to 125°C)

Engineering Contradiction:
Improvevibration frequency stabilityVSAvoidcutting process complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by modifying the cutting angles of the quartz crystal from the conventional AT-cut specifications. Specifically, it adjusts the first angle (between the major face and light axis) to 35-36 degrees and the second angle (between the major face and electrical axis) to 10-12 degrees, which shifts the vibration frequency deviation inflection point to 30-45°C. This parameter optimization enables the resonator to maintain frequency stability within ±20 ppm across the extended temperature range of -40°C to 125°C.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the quartz crystal is cut with specific angles to achieve ±20 ppm frequency deviation, then temperature tolerance is improved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improvetemperature toleranceVSAvoidcutting angle precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent defines specific angle ranges (first angle: 35-36 degrees, second angle: 10-12 degrees) that optimize the vibration frequency characteristics. By specifying ranges rather than single values, the patent balances manufacturing precision requirements with performance goals, allowing for practical fabrication while achieving the desired temperature tolerance and frequency stability.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method provides a quartz crystal resonator with improved temperature tolerance and precision performance, suitable for applications in extreme environments, by maintaining a stable vibration frequency deviation within ±20 ppm from -40 °C to 125 °C, meeting stricter industrial standards.

Implementation Method 1

a quartz crystal resonator includes a quartz crystal cut from a quartz bar... the quartz crystal has a vibration frequency deviation inflection point from about 30 degrees Celsius to about 45 degrees Celsius

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP4391375A1Quartz crystal resonator and manufacturing method thereof
Publication Date: 2024.06.26 DIODES INC
  • EP4391375A1 patent drawingFigure 1
  • EP4391375A1 patent drawingFigure 2
  • EP4391375A1 patent drawingFigure 3

AI summary

A quartz crystal resonator including a quartz crystal obtained from a quartz bar is provided. The quartz bar has a light axis, an electrical axis along a length of the quartz bar, and a mechanical axis that are perpendicular to one another. The quartz crystal has a major face cut from the quartz bar along a cutting plane. The cutting plane has a first angle of about 35° to about 36° with the light axis and has a second angle with the electric axis. The first angle is obtained by rotation about the electric axis, and the second angle is obtained by rotation about the light axis, such that the quartz crystal has a vibration frequency deviation inflection point in a range from about 30 °C to about 45 °C. Methods for making the quartz crystal are also provided.