Vacuum Package Structure With a Hydrogen Diffusion Barrier
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Solution Overview
Problem
Existing package structures fail to maintain a high degree of vacuum due to hydrogen desorption from the getter layer, leading to fluctuations in frequency characteristics of piezoelectric vibration elements.
Innovation Solution
A package structure with a diffusion-inhibiting layer and an adsorption layer that adsorbs hydrogen, preventing its diffusion and maintaining a high degree of vacuum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a getter layer is disposed in the internal space to adsorb gas molecules and increase vacuum degree, then the vacuum degree is improved, but hydrogen from the substrate diffuses into the getter layer causing desorption reactions that reduce vacuum quality
Solution Approach 1:
A diffusion-inhibiting layer is introduced as an intermediary between the substrate and the adsorption layer. This intermediate layer specifically prevents hydrogen atoms generated from the substrate from reaching and reacting with the adsorption layer, thereby eliminating the harmful desorption reaction while preserving the vacuum-maintaining function of the adsorption layer.
Solution Approach 2:
The package structure is segmented into distinct functional layers: a substrate, a diffusion-inhibiting layer, and an adsorption layer. This segmentation allows each layer to perform its specific function independently - the substrate generates hydrogen, the diffusion-inhibiting layer blocks hydrogen migration, and the adsorption layer adsorbs remaining gas molecules - thereby resolving the contradiction between vacuum maintenance and hydrogen desorption prevention.
2Reliability
If hydrogen diffuses into the adsorption layer, then the adsorption layer stores hydrogen and loses its vacuum-maintaining capability, but adding barrier layers increases structural complexity
Solution Approach 1:
The diffusion-inhibiting layer is applied locally only where hydrogen generation occurs - specifically on the inner surface of the substrate facing the internal space. This localized application provides hydrogen blocking functionality precisely where needed, without unnecessarily complicating the entire package structure or adding diffuse barrier layers throughout the device.
Solution Approach 2:
The package structure employs a composite multi-layer configuration combining the substrate material, the diffusion-inhibiting layer material, and the adsorption layer material. Each material is selected for its specific properties - the substrate for structural support, the diffusion-inhibiting layer for hydrogen barrier performance, and the adsorption layer for gas molecule adsorption - creating a composite structure that achieves superior vacuum maintenance without excessive complexity.
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 structure effectively maintains a high degree of vacuum, reducing frequency fluctuations and enhancing the performance stability of piezoelectric vibration elements.
Implementation Method 1
an adsorption layer within the internal space and opposing at least one substrate of the pair of substrates, the adsorption layer constructed to adsorbs at least hydrogen
Implementation Method 2
a diffusion-inhibiting layer which between the at least one substrate and the adsorption layer, and in which hydrogen is more difficult to diffuse compared with in the at least one substrate
Data Source
AI summary
A package structure that includes a pair of substrates arranged to oppose each other so as to form an internal space; a bonding portion sealing the pair of substrates; an element is sealed in the internal space and surrounded by the pair of substrates; an adsorption layer within the internal space and opposing at least one substrate of the pair of substrates, the adsorption layer constructed to adsorbs at least hydrogen; and a diffusion-inhibiting layer between the at least one substrate and the adsorption layer, and in which hydrogen is more difficult to diffuse compared with in the at least one substrate.