Magnetic Head Touch-Down Pad With Embedded Contact Sensor
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Solution Overview
Problem
Conventional Embedded Contact Sensors (ECS) in magnetic recording heads have limited ability to detect touch-down due to recessed alumina, non-minimum clearance points, and wear issues, affecting reliability and longevity.
Innovation Solution
Incorporating a touch-down pad with a leading edge shield and a P1 pedestal, along with strategically positioned thermal fly-height control (TFC) elements, to enhance touch-down detection sensitivity and reliability, using an electrically isolating layer to isolate the ECS and TFC elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ECS is embedded in recessed alumina, then electrical isolation is provided, but touch-down detection sensitivity is reduced
Solution Approach 1:
The patent transitions from a two-dimensional planar ECS design to a three-dimensional protruding structure that extends beyond the alumina surface. This dimensional change allows the sensor to reach the minimum clearance point while maintaining electrical isolation through the insulating layer, simultaneously achieving both reliability and detection sensitivity.
Solution Approach 2:
The patent introduces an insulating layer as an intermediary between the ECS and the alumina substrate. This mediator provides the necessary electrical isolation while allowing the ECS to protrude and make contact at the minimum clearance point, resolving the contradiction between isolation and sensitivity.
2Measurement precision
If the ECS is positioned at the minimum clearance point, then touch-down detection sensitivity is improved, but sensor wear increases
Solution Approach 1:
The patent divides the contact function into two separate components: the ECS provides detection sensitivity at the minimum clearance point, while the TFC element provides a sacrificial contact surface that absorbs wear. This segmentation allows each component to fulfill its specific function without compromising the other.
Solution Approach 2:
The patent employs the TFC element as a disposable or replaceable component that absorbs wear instead of the ECS. The TFC element acts as a sacrificial element that can be replaced when worn, protecting the more valuable and sensitive ECS from degradation.
3Measurement precision
If the ECS protrudes from the magnetic head, then touch-down detection sensitivity is improved, but the ECS becomes subject to wear
Solution Approach 1:
The patent introduces the TFC element as an intermediary between the disk surface and the ECS. This mediator allows the ECS to maintain its protruding position for sensitivity while the TFC element absorbs the mechanical wear from contact, protecting the ECS from harmful wear effects.
Solution Approach 2:
The TFC element serves as a sacrificial component that protrudes and makes contact instead of the ECS. This disposable element absorbs wear and degradation, allowing the ECS to remain intact and functional for extended periods.
4Reliability
If thermal fly-height control elements are added, then touch-down detection reliability is improved, but device complexity increases
Solution Approach 1:
The patent designs the TFC element to serve multiple functions: it provides thermal fly-height control, acts as a sacrificial contact surface to protect the ECS from wear, and contributes to the magnetic head's structural integrity. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent combines the TFC functionality with the touch-down detection structure by integrating the TFC element into the magnetic head assembly near the ECS. This merging of functions and components achieves improved reliability without proportionally increasing overall device complexity.
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
Improves touch-down detection sensitivity and reliability, ensuring consistent contact with the disk surface while minimizing wear on the sensor, thereby enhancing the magnetic head's operational longevity.
Implementation Method 1
Thermal fly-height control (TFC) is a method of altering this distance between the transducers and the disk surface by heating the components of the reader/writer causing thermal expansion of the materials
Implementation Method 2
The ECS typically is constructed of a resistive film which detects contact through a change in resistance
Data Source
AI summary
In one general embodiment, a magnetic head includes a touch-down pad, comprising at least one shielding element positioned between a leading edge of a main magnetic pole and a trailing edge of a lower return pole; an embedded contact sensor (ECS) in an electrically isolating layer, the ECS positioned near an ABS side of the magnetic head and between the leading edge of the main magnetic pole and the trailing edge of the lower return pole; and a first thermal fly-height control (TFC) element positioned away from the ABS side of the magnetic head. Additional systems and methods are also presented.