Piezoelectric Resonator Substrate Insulating Layer Void Prevention
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Solution Overview
Problem
In piezoelectric resonator units, the formation of gaps between the substrate and the metal cover due to extended terminals leads to voids at the joining region, compromising the reliability of the electrical connection.
Innovation Solution
A piezoelectric resonator unit with a substrate having an electrode pattern and a cap joined by a joining material, where an insulating material is formed in the joining region to expose at least part of the electrode pattern, reducing level differences and preventing voids, and a method involving forming an insulating material on the substrate before joining the cap to ensure uniform sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extended terminals are formed from quartz crystal holding terminals towards outer edges of the substrate, then electrical connection is achieved, but gaps are formed at the joining region between substrate and metal cover
Solution Approach 1:
An insulating material is introduced as an intermediary substance in the joining region between the substrate and metal cover. This insulating material fills the gaps created by extended terminals, allowing the sealing material to properly bond the substrate and cover while maintaining electrical connection through the extended terminals.
Solution Approach 2:
The insulating material is applied locally only in the joining region where gaps exist, rather than uniformly across the entire substrate. This localized application addresses the specific problem of gap formation at the joining region while preserving the electrical connection function of the extended terminals.
2Reliability
If sealing material is applied to join substrate and metal cover, then hermetic sealing is achieved, but voids form when gaps are present at the joining region
Solution Approach 1:
The insulating material serves as a mediator that eliminates gaps in the joining region, enabling the sealing material to form a continuous, void-free bond between the substrate and metal cover. Without this intermediary, the sealing material cannot properly fill the gaps created by extended terminals.
Solution Approach 2:
The insulating material is applied to the joining region before the sealing material is applied. This preliminary action prepares the surface by eliminating gaps, ensuring that when the sealing material is subsequently applied, it can form a complete hermetic seal without trapping voids or air bubbles.
3Reliability
If insulating material is formed in the joining region, then level difference is reduced and voids are suppressed, but manufacturing process complexity increases
Solution Approach 1:
The insulating material is applied only in the specific joining region where gaps exist, rather than across the entire substrate. This localized approach minimizes the additional manufacturing steps required while effectively addressing the sealing reliability problem.
Solution Approach 2:
The insulating material is introduced as a simple intermediary substance that can be applied through conventional coating or deposition techniques. This intermediary layer reduces level differences and prevents void formation without requiring complex manufacturing equipment or processes.
Data Source
AI summary
A piezoelectric resonator unit that includes a piezoelectric resonator; a substrate that includes a mounting surface, an electrode pattern on the mounting surface; and a cap joined to the mounting surface of the substrate by a joining material such that the piezoelectric resonator is hermetically sealed. The electrode pattern includes a connection electrode to which the piezoelectric resonator is connected, and an extended electrode that is extended from the connection electrode towards an outer edge of the mounting surface. A joining region on the mounting surface is provided over an entire periphery and surrounds the connection electrode. An insulating material is in the joining region such that at least part of the electrode pattern is exposed therefrom.