Container Flange Configurations for Hermetic Sealing Diffusion Length
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Solution Overview
Problem
Hermetically-sealed hard disk drives face challenges in minimizing leak rates, particularly when using lighter-than-air gases like helium, due to limitations in adhesive-based sealing techniques, especially at corners where adhesion is difficult and gas can escape.
Innovation Solution
The use of inward- and outward-flanged container designs with strategically positioned metal-backed pressure-sensitive adhesive (PSA) tapes to increase the diffusion length and reduce leak rates by ensuring better adhesion and coverage, thereby creating a longer path for gas to escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive-based sealing is used at container corners, then sealing coverage is improved, but adhesion difficulty increases and gas leakage occurs
Solution Approach 1:
The patent transitions from planar sealing to three-dimensional sealing by adding flanges that extend outward from the container surface. This dimensional change creates additional sealing surfaces and allows adhesive to be applied in multiple directions, solving the adhesion difficulty at corners while maintaining reliable sealing coverage.
Solution Approach 2:
The flanges are pre-formed on the container surface before the sealing process. This preliminary structural preparation provides extended surfaces that make adhesive application easier and more reliable, particularly at corner regions where direct planar adhesion would be difficult.
2Reliability
If thin PSA sheet is used, then diffusion area is reduced, but diffusion length is insufficient for hermetic sealing
Solution Approach 1:
The flanges extend the sealing path from a single-dimensional thickness measurement to a multi-dimensional path that travels along the flange surface. This creates a significantly longer diffusion length for gas molecules attempting to escape, transforming the sealing geometry from thin-plane to extended-surface.
Solution Approach 2:
The patent uses thin PSA sheets in conjunction with flanged structures. The thin film provides the adhesive bonding function while the flanged geometry provides the extended diffusion path, combining the advantages of thin-material construction with long sealing length.
3Reliability
If flanged container designs are used, then diffusion length is increased, but device complexity increases
Solution Approach 1:
The flanges are formed as integral parts of thin-walled container structures, allowing complex three-dimensional geometries to be achieved with minimal material and manufacturing steps. The thin-walled construction enables flanged designs that would be cumbersome if made from thick materials.
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 effectively reduces gas leakage by increasing the diffusion length, enhancing the sealing capability and maintaining a hermetic environment for extended periods, even in corner applications where adhesion is challenging.
Implementation Method 1
the critical diffusion length is the smallest distance through or around the PSA sheet (or simply 'PSA') that the enclosed lighter-than-air gas would need to travel to leak out of the container
Data Source
AI summary
A hermetically-sealed container for one or more data storage devices may include a first container part or base including a planar main portion, a plurality of sidewalls extending from the main portion, and a plurality of diffusion length extender flanges extending inward or outward from a corresponding sidewall. A pressure-sensitive adhesive tape, including a layer of adhesive and a layer of low-permeability material, is positioned at the interface or edge of each flange to hermetically seal the container, whereby the diffusion length corresponding to the leakage of gas from the hermetically-sealed container corresponds generally to the width of the flange(s). The hermetically-sealed container may then be filled with a lighter-than-air gas such as helium.