Quartz Crystal Resonator Trimming for Frequency Stability

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Solution Overview

Problem

Quartz crystal resonators face issues with electrical reliability and frequency stability due to disconnection problems and variations caused by fine particles adhering to and detaching from the resonator, leading to unwanted frequency changes.

Innovation Solution

A method involving a quartz crystal resonator with a vibrating portion and a peripheral portion, where a pair of excitation electrodes with varying thickness regions are used, and a two-step trimming process is performed to clean the resonator and adjust the frequency, minimizing unnecessary removal of extended electrodes to prevent disconnection and stabilize frequency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the extended electrode is trimmed to adjust frequency, then the frequency can be adjusted, but disconnection may occur in the extended electrode

Engineering Contradiction:

Improvefrequency adjustment precisionVSAvoidelectrical connection reliability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The trimming process is segmented into two distinct steps: first trimming the vibrating and peripheral portions, then second trimming only the excitation electrode. This segmentation allows frequency adjustment while preserving the extended electrode's structural integrity and avoiding disconnection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of trimming the entire extended electrode, only the necessary portion of the excitation electrode is trimmed in the second trimming step. This partial action achieves frequency adjustment while minimizing damage to the extended electrode structure.

Inventive Principle:

Principle #16Partial or excessive action

2Reliability

If the extended electrode thickness is reduced on stepped portion, then disconnection is reduced, but frequency stability may be affected by fine particles

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidfrequency stability

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The first trimming is performed as a preliminary action to remove fine particles and contaminants from the resonator surface before the second trimming adjusts the frequency. This preliminary cleaning action prevents frequency variations caused by particle adhesion.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Fine particles and contaminants are extracted or removed from the resonator surface during the first trimming process, eliminating the source of frequency instability while preserving the extended electrode structure.

Inventive Principle:

Principle #2Taking out (Extraction)

3Manufacturing precision

If the entire electrode is dry-etched to uniformly process, then uniform processing is achieved, but disconnection occurs in the extended electrode

Engineering Contradiction:

Improveprocessing uniformityVSAvoidelectrical connection reliability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

Different trimming actions are applied to different local regions: the first trimming processes the vibrating and peripheral portions, while the second trimming specifically targets the excitation electrode. This local differentiation achieves necessary processing without causing extended electrode disconnection.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The uniform dry-etching process is segmented into two steps with different scopes: first trimming covers broader areas (vibrating and peripheral portions), while second trimming focuses only on the excitation electrode. This segmentation maintains processing effectiveness while protecting the extended electrode.

Inventive Principle:

Principle #1Segmentation

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 solution improves electrical reliability and stabilizes frequency characteristics by effectively cleaning the resonator and adjusting the frequency while reducing the risk of disconnection and frequency variations.

Implementation Method 1

conducting a first trimming of the vibrating portion and the peripheral portion; and conducting a second trimming of part of one of the excitation electrodes on the vibrating portion

Methodology Applied

Scientific EffectMaterial removal through trimming: Ablation

Data Source

PatentUS10523173B2Quartz crystal resonator and method for manufacturing the same, and quartz crystal resonator unit and method for manufacturing the same

Publication Date: 2019.12.31 MURATA MFG CO LTD

AI summary

A method for manufacturing a quartz crystal resonator that includes a quartz crystal blank having a vibrating portion including a center of a principal surface of the quartz crystal blank when viewed in plan from a direction normal to the principal surface and a peripheral portion adjacent to the vibrating portion, a pair of excitation electrodes disposed opposite to each other with the vibrating portion interposed therebetween, a pair of electrode pads disposed on the peripheral portion, and a pair of extended electrodes each extending from the vibrating portion to the peripheral portion to electrically connect one excitation electrode to a corresponding electrode pad, where the method includes conducting a first trimming of the vibrating portion and the peripheral portion; and conducting a second trimming of part of one of the excitation electrodes on the vibrating portion.