Hard Disk Drive Base Plate Sealing via Impregnant
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Solution Overview
Problem
The low metal density areas in base plates manufactured by aluminum die casting, such as those used in hard disk drives, pose challenges in maintaining airtightness within the housing due to air leakage through minute cavities and cast portions like gates and overflows.
Innovation Solution
A base plate design incorporating an electrodeposition coating film and an impregnant, where the impregnant covers the low metal density areas exposed at the worked surface, effectively sealing minute cavities and improving airtightness by replacing the electrodeposition coating film in these regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aluminum die casting process is used to manufacture base plate, then manufacturing efficiency and cost are improved, but airtightness of interior space deteriorates due to low metal density areas and minute cavities
Solution Approach 1:
The patent applies different treatments to different surfaces of the base plate. The coated surface receives electrodeposition coating while the worked surface (with low metal density) receives impregnant treatment. This local differentiation ensures that each surface is treated according to its specific characteristics and requirements, resolving the contradiction between maintaining manufacturing efficiency and improving airtightness.
Solution Approach 2:
The impregnant acts as an intermediary substance that fills the minute cavities and low metal density areas in the worked surface. This intermediary material bridges the gap between the defective casting structure and the requirement for airtightness, allowing the base plate to maintain both manufacturing efficiency and reliable sealing performance.
2Strength
If electrodeposition coating film is applied to cover the surface, then surface protection and appearance are improved, but airtightness deteriorates because the coating cannot seal minute cavities in low metal density areas
Solution Approach 1:
The patent recognizes that different surfaces have different requirements. The coated surface needs protection and appearance (electrodeposition), while the worked surface needs airtightness (impregnant). By applying different treatments to different surfaces, the patent resolves the contradiction between surface protection and airtightness.
Solution Approach 2:
The impregnant penetrates and fills the minute cavities in the worked surface, creating a copied or replicated sealing structure within the cavities. This allows the low metal density areas to achieve airtightness equivalent to solid metal, resolving the contradiction between surface coating and cavity 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 enhances the airtightness of the interior space within the hard disk drive housing by ensuring the impregnant can satisfactorily infiltrate and seal the cavities, reducing air penetration and maintaining a secure gas environment, such as helium, within the device.
Implementation Method 1
the worked surface can be satisfactorily impregnated with the impregnant because minute cavities in the base body are exposed to an outside at the worked surface
Implementation Method 2
an electrodeposition coating film arranged to cover a surface of the base body
Data Source
AI summary
A base plate is arranged to define a portion of a housing of a hard disk drive, and includes a base body defined by casting, and an electrodeposition coating film arranged to cover a surface of the base body. The surface of the base body includes a coated surface covered with the electrodeposition coating film, and a flat worked surface exposed from the electrodeposition coating film. The worked surface may include a gate position to which a gate has been connected at the time of the casting. At least a portion of the worked surface is covered with an impregnant.