Laser Sealed Micromechanical Cavity Recess Design
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Solution Overview
Problem
Micromechanical components face issues with local stress peaks during the sealing process, leading to potential crack formation and reduced service life due to uneven thermal and mechanical loads.
Innovation Solution
A method involving the formation of a recess on the surface away from the access opening to distribute and reduce local stresses, which includes introducing energy and heat to seal the access channel using a laser, thereby minimizing mechanical stress and preventing crack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the access opening is sealed by local heating with a laser, then the access channel is hermetically sealed, but local stresses and stress peaks occur at the sealed access opening leading to crack formation
Solution Approach 1:
The sealed access opening is divided into multiple smaller sealed access openings. This segmentation distributes the stress concentration over multiple locations rather than a single large seal, reducing the stress peak at each individual seal while maintaining overall hermetic sealing effectiveness.
2Reliability
If the access channel is sealed by laser heating, then hermetic sealing is achieved, but the material area becomes susceptible to crack formations under thermal or mechanical loads
Solution Approach 1:
By segmenting the sealed access opening into multiple smaller openings, the stress concentration that would otherwise occur at a single large seal is distributed across multiple smaller seals. This reduces the likelihood of crack formation under thermal or mechanical loads while preserving hermetic sealing.
3Productivity
If a large access channel is used for gas filling, then the cavity can be flooded with desired gas, but the sealed area experiences high local stresses during solidification
Solution Approach 1:
The large access channel is divided into multiple smaller access channels. This allows efficient gas filling through multiple openings while distributing the stress concentration over multiple smaller sealed areas, reducing the local stress at each seal compared to a single large seal.
Solution Approach 2:
The access openings are strategically positioned and sized to optimize both gas filling efficiency and stress distribution. By controlling the local characteristics of each access opening, the design achieves efficient gas filling while minimizing stress concentration at the sealed areas.
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 method effectively reduces local stresses, preventing crack formation and enhancing the mechanical robustness and service life of micromechanical components by distributing mechanical stress across a larger material area, making them more resistant to thermal and mechanical loads.
Implementation Method 1
the access opening is sealed by introducing energy and heat into an absorbing part of the substrate or the cap with the aid of a laser
Implementation Method 2
the area around the access channel is locally heated with the aid of a laser, the substrate material liquefies locally
Implementation Method 3
it is possible with the aid of the recess to reduce mechanical stresses through elastic deformation
Data Source
AI summary
A method is provided for manufacturing a micromechanical component including a substrate and a cap connected to the substrate and together with the substrate enclosing a first cavity, a first pressure prevailing and a first gas mixture with a first chemical composition being enclosed in the first cavity. An access opening, connecting the first cavity to surroundings of the micromechanical component, is formed in the substrate or in the cap. The first pressure and/or the first chemical composition are adjusted in the first cavity. The access opening is sealed by introducing energy and heat into an absorbing part of the substrate or the cap with the aid of a laser. A recess is formed in a surface of the substrate or of the cap facing away from the first cavity in the area of the access opening for reducing local stresses occurring at a sealed access opening.