Piezoelectric Resonator Diffusion Bonding for Compact Packaging
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Solution Overview
Problem
Piezoelectric resonator devices face challenges in reducing package size and height due to the use of metal paste sealing materials, which generate gas during high-temperature bonding, leading to deteriorated oscillation characteristics and limitations in size reduction.
Innovation Solution
A piezoelectric resonator device with a sandwich structure using physical vapor deposition (PVD) films for bonding patterns, eliminating the need for metal paste sealing materials and reducing gas generation, allowing for smaller sizes and improved bonding without high-temperature heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal paste sealing material is used for bonding the first sealing member, second sealing member and crystal resonator plate, then bonding strength is improved, but package height increases and gas is generated during high-temperature heating
Solution Approach 1:
The patent changes the bonding method from high-temperature melting of metal paste to diffusion bonding at lower temperatures (400-600°C). This parameter change in bonding temperature and mechanism enables the use of thinner bonding layers while maintaining adequate bonding strength, thereby reducing package height without sacrificing bonding performance
Solution Approach 2:
The patent replaces the thermal-melting mechanism of metal paste bonding with a diffusion bonding mechanism. Instead of relying on high-temperature melting and solidification, the invention uses atomic diffusion across the bonding interface, which occurs at lower temperatures and allows for thinner bonding layers, thus reducing package height while maintaining bonding strength
2Strength
If metal paste sealing material is used for bonding, then bonding is achieved, but gas is generated during high-temperature heating which deteriorates oscillation characteristics
Solution Approach 1:
The patent changes the bonding temperature parameter from high-temperature (above melting point of metal paste, typically >800°C) to lower temperature (400-600°C) diffusion bonding. This parameter change eliminates the phase change process that generates gas, thereby preventing deterioration of oscillation characteristics while maintaining bonding strength through diffusion bonding
Solution Approach 2:
The patent substitutes the high-temperature thermal-melting bonding mechanism with a lower-temperature diffusion bonding mechanism. This substitution eliminates the gas generation problem associated with metal paste melting while achieving adequate bonding strength through atomic diffusion, thus preventing harmful gas effects on oscillation characteristics
3Strength
If metal paste sealing material is used with large shape, then bonding coverage is ensured, but package size cannot be reduced
Solution Approach 1:
The patent changes the bonding layer thickness parameter by using diffusion bonding instead of metal paste. This enables the bonding layer to be much thinner (micrometer scale) compared to metal paste (tens of micrometers), allowing for reduced package size while maintaining adequate bonding coverage through the diffusion bonding mechanism
Solution Approach 2:
The patent employs thin film bonding patterns made of PVD films for diffusion bonding. These thin films provide sufficient bonding coverage area while having minimal thickness, enabling the package size to be reduced compared to the thick metal paste sealing material, thus achieving both adequate bonding coverage and compact package dimensions
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 enables reduced size and height in piezoelectric resonator devices while preventing gas generation and maintaining stable oscillation characteristics, contributing to cost reduction and improved mechanical strength.
Implementation Method 1
a resonator-plate-side first bonding pattern formed on the first main surface of the piezoelectric resonator plate so as to be bonded to the first sealing member, the resonator-plate-side first bonding pattern being constituted by a base PVD film deposited on the first main surface by physical vapor deposition and an electrode PVD film deposited on the base PVD film by the physical vapor deposition
Implementation Method 2
the sealing-member-side first bonding pattern is bonded to the resonator-plate-side first bonding pattern by diffusion bonding, and the sealing-member-side second bonding pattern is bonded to the resonator-plate-side second bonding pattern by the diffusion bonding
Data Source
AI summary
A piezoelectric resonator device having a sandwich structure is provided, which can avoid gas generation with reduced size or height. A crystal resonator includes a crystal resonator plate, a first sealing member and a second sealing member. A sealing-member-side first bonding pattern and a sealing-member-side second bonding pattern, both to be bonded to the crystal resonator plate, are formed respectively on the first and second sealing members. On the crystal resonator plate, a resonator-plate-side first bonding pattern to be bonded to the first sealing member is formed on a first main surface and a resonator-plate-side second bonding pattern to be bonded to the second sealing member is formed on a second main surface. The sealing-member-side first bonding pattern is bonded to the resonator-plate-side first bonding pattern, and the sealing-member-side second bonding pattern is bonded to the resonator-plate-side second bonding pattern, both by diffusion bonding.