Hermetic HDA Sealing via Soldering and Merging
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Solution Overview
Problem
Existing hermetic sealing methods for Head Disk Assemblies (HDAs) face challenges such as high temperatures required for welding, material compatibility issues, and the need for multiple components to isolate components from welding temperatures, leading to distortion and increased costs.
Innovation Solution
A novel design incorporating a semi-hermetic and hermetic seal in series, achieved through a soldering technique using a solder alloy or reactive cross-linking polymer, which allows for flexible assembly and testing under a desired atmosphere, with the semi-hermetic seal being temporary and the hermetic seal permanent, minimizing component count and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If welding is used to achieve hermetic seal, then sealing reliability is improved, but manufacturing complexity and cost increase due to need for multiple components and high temperature isolation
Solution Approach 1:
The patent combines the hermetic seal and semi-hermetic seal functions into a single sealing component (the cover) with integrated sealing structures. The cover includes both a hermetic seal structure (for permanent sealing) and a semi-hermetic seal structure (for temporary sealing during assembly), eliminating the need for separate components to isolate welding temperatures and reducing overall device complexity.
Solution Approach 2:
The sealing function is segmented into two distinct sealing structures within the same component: a hermetic seal for permanent sealing and a semi-hermetic seal for temporary sealing during assembly. This segmentation allows each seal type to perform its specific function optimally while being integrated into a single manufacturable component.
2Reliability
If welding is used to achieve hermetic seal, then sealing reliability is improved, but manufacturing cost and difficulty increase due to high temperature requirements
Solution Approach 1:
The patent changes the sealing mechanism from high-temperature welding to low-temperature soldering. The hermetic seal is formed by soldering the hermetic seal structure to the base casting, which occurs at significantly lower temperatures than welding. This parameter change in sealing temperature makes the manufacturing process easier and reduces the need for complex high-temperature isolation measures.
Solution Approach 2:
The patent replaces the mechanical/thermal welding process with a soldering process that uses molten soldering material to form the hermetic seal. This substitution eliminates the high temperature requirements of welding while maintaining sealing reliability, thereby improving ease of manufacture.
3Reliability
If high temperature welding is used, then hermetic seal is achieved, but component distortion occurs
Solution Approach 1:
The patent changes the sealing temperature parameter from high-temperature welding to low-temperature soldering. The soldering process occurs at temperatures that do not cause thermal distortion of the HDA components, while still achieving hermetic sealing reliability through the molten soldering material that forms strong bonds between the hermetic seal structure and the base casting.
4Reliability
If multiple components are used for welding isolation, then sealing reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the functions of multiple isolation components into the cover itself. The cover includes integrated hermetic and semi-hermetic seal structures that perform both sealing functions without requiring separate components for welding isolation. This reduces the total component count while maintaining sealing reliability.
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
Enables cost-effective hermetic sealing of HDAs with reduced component complexity, allowing for flexible assembly and rework if necessary, while maintaining a stable atmosphere without the limitations of high-temperature welding.
Implementation Method 1
a hermetic seal comprising a soldering material that is melted to seal the cover to the base casting
Implementation Method 2
hermetic seal comprising a reactive cross-linking polymer that is activated to seal the cover to the base casting
Data Source
AI summary
A sealed head disk assembly has a cover for enclosing major components of the head disk assembly. The cover has a hermetic seal encompassing an outer perimeter of the cover and a semi-hermetic seal inside a perimeter of the hermetic seal. The hermetic seal and semi-hermetic seal are juxtaposed to at least one complementary surface on the base casting. The base casting, which provides attachment points for the major components of the head disk assembly has at least one complementary surface.