Soft Bumper Pads for HDD Slider Media Damage Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The increased areal density capacity in hard disk drives has made the head/media interface critical and stressful, leading to susceptibility of data loss or error due to accidental head/disk interactions and thermal asperities during dynamic events like operating shocks and load/unload processes, where existing solutions do not effectively mitigate media damage and thermal erasures.
Innovation Solution
The implementation of soft bumper pads made of silicon with a diamond-like carbon (DLC) coating at critical positions on the air-bearing surface of the slider, which absorb energy and provide thermal conductivity to prevent media damage during head/disk interactions, using a combination of subtractive and additive manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the active fly height is reduced to increase areal density capacity, then the recording density is improved, but the head/media interface becomes more critical and susceptible to media damage and thermal erasures
Solution Approach 1:
The patent applies beforehand cushioning by depositing a soft bumper pad layer (50-300 Å thick) made of materials with high energy absorption capability (loss tangent ≥ 0.05) at the corners and edges of the air-bearing surface before head-media contact occurs. This cushioning layer is positioned in advance to absorb impact energy during dynamic events such as load/unload operations and operating shocks, preventing direct hard contact between the rigid AlTiC substrate and the magnetic media, thereby reducing media damage and thermal erasures while maintaining the reduced fly height necessary for high areal density capacity
2Quantity of substance
If the carbon overcoat and lubricant thickness are decreased to meet areal density gain requirements, then the recording capacity is improved, but the protective layers become thinner and more vulnerable to damage
Solution Approach 1:
The soft bumper pad layer is deposited in advance at critical locations (corners and edges) where impact forces concentrate during head-media interactions. This beforehand cushioning compensates for the reduced thickness of protective layers (COC and lubricant) by providing an energy-absorbing interface that prevents direct transmission of impact forces to the thinned protective layers, allowing the system to achieve high areal density capacity while maintaining adequate protection against media damage
Solution Approach 2:
The patent applies local quality by concentrating the soft bumper pad material specifically at the corners and edges of the air-bearing surface where impact forces are most concentrated during dynamic events, rather than uniformly across the entire surface. This localized application provides enhanced protection at the most vulnerable points while maintaining the overall aerodynamic performance and minimizing interference with the thinned protective layers in other areas
3Reliability
If soft bumper pad material is added to absorb contact forces, then media damage is reduced, but the slider mass increases
Solution Approach 1:
The soft bumper pad layer is applied locally only at the corners and edges of the air-bearing surface where impact forces concentrate during head-media interactions, rather than uniformly across the entire slider surface. This localized application minimizes the total mass of the bumper pad material while providing protection at the most critical locations, thus reducing media damage without significantly increasing slider mass and maintaining aerodynamic performance
Solution Approach 2:
The patent controls the thickness parameter of the soft bumper pad layer within a specific range of 50-300 Å, which is sufficient to absorb impact energy and protect the media but thin enough to minimize mass addition. This parameter optimization ensures that the bumper pad provides adequate media damage mitigation while keeping the slider mass increase negligible and the aerodynamic characteristics essentially unchanged
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
The soft bumper pads effectively absorb contact forces, reduce thermal stresses, and maintain aerodynamic stability, thereby extending the time-to-failure of the hard disk drive by minimizing media damage and thermal erasures during adverse interactions.
Implementation Method 1
The slider includes a soft bumper pad layer at the corners and/or edges of the air-bearing surface that is formed of a material having an energy absorption capability characterized by a loss tangent of greater than or equal to 0.05
Implementation Method 2
The implementation of soft bumper pads made of silicon with a diamond-like carbon (DLC) coating at critical positions on the air-bearing surface of the slider, which absorb energy and provide thermal conductivity to prevent media damage during head/disk interactions
Data Source
AI summary
A slider design for a hard disk drive (HDD) features an air-bearing surface (ABS) topography with soft bumper pads (SBP) formed proximally to corners of the leading edge and the trailing edge. The bumper pads are formed by a process that combines the use of a first photomask for subtractive etching of the ABS to form pedestals, followed by additive depositions onto the pedestals using a second lift-off photomask. The additive process deposits sequences of Si layers and diamond-like carbon (DLC) layers to produce a soft bumper pad that is energy absorbing and heat conducting, thereby protecting the recording media from surface damage and thermal erasures.