Adhesive Hermetic Seal Spacing Mechanism for HDD Leak Rate Reduction

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Solution Overview

Problem

Hermetically sealed hard disk drives and storage systems face challenges in achieving a low leak rate due to thermal mismatch stresses and uneven adhesive thickness in adhesive-based sidewall-in-groove sealing techniques, which can lead to increased diffusion area and leak rates.

Innovation Solution

The use of spacing mechanisms, such as thin wires or metal foil strips, and protrusions to center the sidewalls within the groove ensures equal adhesive thickness and minimizes thermal mismatch stresses, promoting capillary action and a hermetic seal by maintaining a consistent gap for adhesive flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If adhesive-based sidewall-in-groove sealing is used to hermetically seal HDDs, then the sealing process becomes simpler and more cost-effective, but thermal mismatch stresses and uneven adhesive thickness increase the leak rate

Engineering Contradiction:

Improvesealing process simplicityVSAvoidhermetic seal integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-positioning spacing mechanisms (such as spacers or positioning structures) on the groove surfaces before applying the adhesive. These pre-positioned elements ensure that the adhesive is distributed uniformly and that the sidewall is centered in the groove, preventing uneven adhesive thickness and reducing thermal mismatch stresses before the sealing process begins.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes physical parameters by introducing spacing mechanisms that control the gap between the sidewall and groove surfaces. This spacing mechanism adjusts the adhesive thickness parameter to be uniform, and modifies the thermal stress distribution by maintaining consistent gaps, thereby reducing the leak rate while keeping the adhesive-based sealing method simple and cost-effective.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If adhesive is applied to seal the interface between cover and base, then hermetic sealing is achieved, but thermal mismatch stresses cause uneven adhesive thickness and increased leak rate

Engineering Contradiction:

Improvehermetic sealingVSAvoidadhesive thickness uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent introduces spacing mechanisms as intermediary elements between the groove surfaces and the adhesive. These intermediaries (such as spacers or positioning structures) mediate the adhesive application process by maintaining consistent gaps, ensuring uniform adhesive thickness, and preventing direct contact between the sidewall and groove surfaces that would cause uneven distribution.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The spacing mechanisms are pre-positioned on the groove surfaces before adhesive application. This preliminary positioning ensures that when adhesive is applied, it flows uniformly through the pre-defined gaps, resulting in consistent adhesive thickness and reducing thermal mismatch stresses caused by uneven distribution.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If adhesive thickness varies in the seal interface, then the sealing process accommodates manufacturing tolerances, but the diffusion area increases and leak rate increases

Engineering Contradiction:

Improvetolerance accommodationVSAvoidleak rate

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the adhesive thickness parameter from variable to uniform by introducing spacing mechanisms. These mechanisms maintain a constant gap between the sidewall and groove surfaces, ensuring that the adhesive thickness parameter remains consistent throughout the seal interface, thereby reducing the diffusion area and leak rate while still accommodating manufacturing tolerances through the spacing mechanism design.

Inventive Principle:

Principle #35Parameter changes

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 reduces the leak rate by ensuring uniform adhesive distribution and minimizing thermal stresses, thereby enhancing the reliability and efficiency of the hermetic sealing process.

Implementation Method 1

promoting capillary action and a hermetic seal by maintaining a consistent gap for adhesive flow

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Data Source

PatentUS10121518B1Reducing leak rate in adhesive-based hermetically-sealed data storage devices and systems

Publication Date: 2018.11.06 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

A hermetically-sealed container for one or more data storage devices may include a base having grooves, and corresponding sidewalls disposed within each groove, with an adhesive disposed within each groove and bonding each sidewall to the base, and with gap spacing mechanisms positioned within each groove between the corresponding sidewall and the base, thereby ensuring a gap for sufficient flow of the adhesive between each sidewall and the base. The adhesive may be a liquid-based epoxy adhesive, and whereby the spacing mechanisms enable sufficient capillary action to wet all the surfaces to form a sound hermetic bond or seal between the sidewalls and the base. The container may, then, be filled with a lighter-than-air gas such as helium.