Disk Drive Base Unit Groove Design for Helium Seal Integrity
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Solution Overview
Problem
Hard disk drives filled with low-density gases like helium face challenges in maintaining airtightness due to gas leakage through minute gaps, especially when using connectors to seal through holes, which can result in inadequate adhesive strength and sealing areas.
Innovation Solution
A base unit design with a bottom plate featuring a window portion and surrounding grooves, where an adhesive layer forms a continuous closed loop around the window, and communicating grooves allow gas bubbles to be discharged externally, ensuring a strong seal and preventing gas leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a connector is used to seal the through hole, then the airtightness is improved, but gas bubbles may be introduced into the adhesive or groove, resulting in insufficient adhesive strength and sealing area
Solution Approach 1:
The groove is segmented into a sealed portion (where adhesive is held) and a communicating portion (where gas bubbles can escape). This segmentation allows the groove to serve dual functions: maintaining sealing while providing an escape route for gas bubbles during the adhesive bonding process, thus preventing bubble entrapment that would compromise adhesive strength.
Solution Approach 2:
The communicating groove acts as an intermediary channel between the sealed groove area and the external environment. It provides a controlled pathway for gas bubbles to escape during adhesive application, mediating between the need for a sealed adhesive bond and the need to eliminate gas pockets that would weaken the bond.
2Reliability
If adhesive is applied to seal the through hole, then the sealing area is improved, but gas leakage may occur through minute gaps, especially with low-density gases like helium
Solution Approach 1:
The adhesive layer forms a flexible sealing film that conformally seals the through hole and surrounding areas. This flexible film adaptation ensures complete coverage and sealing, preventing gas leakage through minute gaps while maintaining the necessary sealing area for airtightness.
Solution Approach 2:
The solution uses a composite approach combining the adhesive material (for sealing) with the groove structure (for bubble management). This composite system of adhesive plus structured groove provides both the sealing function and the gas bubble elimination function, addressing both sealing area and gas leakage prevention.
3Strength
If the groove is completely sealed to hold adhesive, then adhesive strength is improved, but gas bubbles cannot escape, resulting in insufficient sealing area
Solution Approach 1:
The groove is divided into functional segments: the sealed portion holds the adhesive for bonding strength, while the communicating portion allows gas bubble escape. This segmentation resolves the contradiction by providing both adhesive containment and bubble venting pathways within the same groove structure.
Solution Approach 2:
Instead of completely sealing the groove, the design uses partial sealing with a communicating portion left open for bubble escape. This partial action approach maintains sufficient adhesive holding while providing the necessary escape route for gas bubbles, achieving both adhesive strength and sealing area requirements.
Data Source
AI summary
A base member of a disk drive apparatus includes a window portion, a first groove, and a communicating groove. The window portion passes through a bottom plate portion of the base member in an axial direction. The first groove is defined in an upper surface of the bottom plate portion around the window portion. A connector includes a board portion and an electrode terminal on a lower surface of the board portion. The board portion is on the upper surface of the bottom plate portion to cover the window portion, the first groove, and a portion of the communicating groove. The communicating groove extends from the first groove up to a position outside of an outer circumferential portion of the connector. An adhesive layer is between the upper surface of the bottom plate portion and the lower surface of the board portion.