Glass Enclosure Weld Layout for Hermetic Sealing Under Thermal Stress
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Solution Overview
Problem
Existing enclosures for electronic devices face challenges in mechanical stability, particularly under environmental stress, due to thermal stress induced by single laser weld lines.
Innovation Solution
The implementation of at least two laser weld lines for each contact surface, with the second weld line overlapping the first, reduces thermal stress and enhances mechanical stability by distributing heat accumulation and relieving stress zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single laser weld line is used to hermetically seal the enclosure, then the sealing function is achieved, but thermal stress accumulates and mechanical stability deteriorates
Solution Approach 1:
The single laser weld line is segmented into multiple weld lines (first, second, and third weld lines) that are spatially separated. Each weld line contributes to the overall hermetic sealing while distributing the thermal stress across multiple zones, preventing stress concentration that would occur with a single continuous weld line.
Solution Approach 2:
Different regions of the enclosure receive different welding treatments. The first weld line provides primary sealing, while the second and third weld lines provide additional sealing and stress distribution. This local differentiation allows the structure to achieve both hermetic sealing and mechanical stability through strategically placed weld zones rather than uniform welding throughout.
2Reliability
If laser welding is performed to join substrates, then hermetic sealing is achieved, but thermal stress and micro-cracks are induced in the glass material
Solution Approach 1:
The welding process is segmented into multiple separate laser weld lines instead of a single continuous weld. This segmentation distributes the thermal input across multiple discrete zones, allowing heat to dissipate between weld lines and preventing excessive thermal stress accumulation that would lead to micro-cracks in the glass substrates.
Solution Approach 2:
The laser welding is performed in periodic intervals with distinct first, second, and third weld lines rather than as a continuous process. This periodic action allows thermal fields to partially dissipate between welding events, reducing cumulative thermal stress and preventing the formation of micro-cracks while still achieving hermetic sealing.
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 approach significantly improves the mechanical stability of hermetically sealed enclosures, reducing thermal stress and potential micro-cracks, thereby enhancing the robustness of the enclosure under various environmental conditions.
Implementation Method 1
introducing a first laser weld line in the enclosure, introducing a second laser weld line at the same position as the first laser weld-line or at a position close to or overlapping with the first laser weld line
Implementation Method 2
the second weld line overlapping the first reduces thermal stress and enhances mechanical stability by distributing heat accumulation and relieving stress zones
Data Source
Figure 1a~1c
Figure 2~3
Figure 4
AI summary
An enclosure is shown, comprising at least a base substrate and a cover substrate, which constitute at least a part of the enclosure, and a function zone situated such that it is circumferentially enclosed in the enclosure. At least the cover substrate comprises preferably a glass or glass-like material. The base substrate and the cover substrate are hermetically welded by means of at least one laser weld line, where the laser weld line comprises a height HL in a direction perpendicular to its connecting plane, and wherein the mechanical stress in the at least one laser weld line is reduced, thus improving the mechanical stability of the enclosure.