Quartz Crystal Device Electrode Positioning for DLD Stability
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Solution Overview
Problem
The existing surface mount type quartz crystal devices face issues with the Drive Level Dependence (DLD) characteristic due to stress from thermal expansion differences between the quartz-crystal vibrating piece and the ceramic package, leading to changes in frequency characteristics, and the attachment of blank scrap to the pedestal blank can further alter these characteristics.
Innovation Solution
A surface mount type quartz crystal device is designed with a ceramic package and a pedestal blank made of the same quartz-crystal material, where the pedestal blank is placed within the package via a conductive adhesive, and the excitation electrodes are positioned to avoid overlap with the adhesive, preventing blank scrap attachment and minimizing stress effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pedestal blank is closely formed with the quartz-crystal vibrating piece, then the stress from thermal expansion difference is reduced, but blank scrap attaches to the quartz-crystal vibrating piece changing the DLD characteristic
Solution Approach 1:
The patent extracts the harmful element (blank scrap) from the system by positioning the excitation electrodes to extend beyond the pedestal blank's outer peripheral side, ensuring that any scrap remaining on the pedestal blank cannot attach to the electrodes. This spatial separation removes the source of DLD characteristic changes without compromising the stress-reduction benefit of close formation.
Solution Approach 2:
The patent introduces an intermediary spatial relationship where the excitation electrodes extend beyond the pedestal blank boundary, creating a buffer zone that prevents direct contact between potential scrap contaminants and the functional electrodes. This intermediary positioning resolves the contradiction by allowing close formation while blocking the harmful attachment path.
2Strength
If the conductive adhesive is applied to the entire outer peripheral side of the pedestal blank, then bonding strength is improved, but the adhesive overlaps with the excitation electrode causing performance degradation
Solution Approach 1:
The patent applies local quality by restricting the conductive adhesive application to specific regions that do not overlap with the excitation electrodes. The adhesive is applied only to areas where it provides bonding strength without interfering with electrode function, creating a spatially differentiated quality distribution that satisfies both bonding and performance requirements.
Solution Approach 2:
The patent segments the bonding function from the electrode function by positioning them in separate spatial zones. The excitation electrodes extend beyond the pedestal blank while the adhesive is confined to non-overlapping regions, dividing the structure into functional segments that independently fulfill their roles without interference.
3Reliability
If additional polishing or washing processes are added to remove blank scrap, then the DLD characteristic stability is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent implements preliminary action by designing the electrode positioning and adhesive application pattern in advance to prevent blank scrap attachment from occurring in the first place. By proactively configuring the structure to eliminate scrap attachment risks, the invention avoids the need for subsequent polishing or washing processes, reducing manufacturing complexity while maintaining DLD characteristic stability.
Solution Approach 2:
The patent converts the potential harm of blank scrap attachment into a benefit by using the electrode extension design to define a natural boundary that prevents scrap contact. The structural configuration itself becomes the protective mechanism, transforming what could be a contamination problem into a self-preventing design feature that eliminates additional processing steps.
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
This design reduces the attachment of blank scrap to the excitation electrodes, stabilizes the DLD characteristic, and avoids the need for additional polishing or washing of the pedestal blank, thereby maintaining manufacturing cost-effectiveness and preventing frequency variations.
Implementation Method 1
The pedestal blank is placed within the ceramic package via a conductive adhesive
Implementation Method 2
a quartz-crystal vibrating piece is placed on the package
Implementation Method 3
the stress is applied to the quartz-crystal vibrating piece due to a difference of thermal expansion between a quartz-crystal material that forms the quartz-crystal vibrating piece and the package
Data Source
AI summary
A surface mount type quartz crystal device according to a first aspect of the disclosure includes a ceramic package, a pedestal blank, a quartz-crystal vibrating piece. The pedestal blank is placed within the ceramic package via a conductive adhesive. The quartz-crystal vibrating piece is placed on the pedestal blank. The conductive adhesive is formed along an outer peripheral side of the pedestal blank so as to avoid overlap with the excitation electrode viewed in a normal direction of the excitation electrode. The pedestal blank is formed to avoid a region where a distance from the quartz-crystal vibrating piece is equal to or smaller than a size of a clearance between the pedestal blank and the quartz-crystal vibrating piece at the outer peripheral side, in a region where the excitation electrode faces at the pedestal blank side viewed in the normal direction.