Magnetic Head Shield Stopper Layer Thermal Expansion Control
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Solution Overview
Problem
Magnetic heads for perpendicular magnetic recording face challenges in maintaining a small throat height to improve overwrite properties and prevent slider collision, as the shield layer's end face protrusion due to heat generated by the coil complicates reducing the flying height and enhancing recording density and signal-to-noise ratio.
Innovation Solution
Incorporating a stopper layer made of nonmagnetic material with a low thermal expansion coefficient adjacent to the shield layer to suppress protrusion, along with a gap layer between the pole and shield layers, and utilizing materials like SiC, AlN, or W for the stopper layer to manage thermal expansion and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the throat height is reduced to improve overwrite properties and prevent slider collision, then the overwrite capability and recording density improve, but the shield layer's end face protrusion due to thermal expansion becomes more critical and difficult to control
Solution Approach 1:
A stopper layer is introduced as an intermediary component between the shield layer and the gap layer. This stopper layer serves as a mediator that physically restricts the thermal expansion of the shield layer while maintaining the electrical insulation function. The stopper layer absorbs the thermal expansion stress and prevents it from affecting the throat height and shield position, thus resolving the contradiction between reduced throat height and thermal expansion control.
Solution Approach 2:
The invention changes the material parameters of the stopper layer, specifically selecting materials with low thermal expansion coefficients and appropriate mechanical properties. By carefully controlling the thickness and material composition of the stopper layer, the design optimizes the balance between preventing shield protrusion and maintaining electrical insulation, enabling precise throat height control even at reduced dimensions.
2Manufacturing precision
If the flying height is reduced to enhance recording density and signal-to-noise ratio, then the recording performance improves, but the risk of slider collision increases and thermal management becomes more challenging
Solution Approach 1:
The stopper layer is pre-configured in the head structure before the slider contacts the recording medium during operation. This preliminary structural arrangement ensures that the shield layer's thermal expansion is restricted in advance, preventing protrusion that would otherwise occur during high-temperature operation. The stopper layer is positioned and dimensioned beforehand to accommodate expected thermal expansion while maintaining the reduced flying height geometry.
3Loss of energy
If materials with high thermal conductivity are used for the stopper layer to improve heat dissipation, then thermal management improves, but the material selection becomes more constrained and manufacturing complexity increases
Solution Approach 1:
The invention applies local quality by providing heat dissipation functionality specifically at the stopper layer where thermal expansion occurs, rather than requiring the entire head structure to use high-thermal-conductivity materials. The stopper layer is selectively designed with appropriate thermal conductivity properties, while other components can use materials optimized for their specific functions. This localized approach to thermal management simplifies overall manufacturing while effectively addressing heat dissipation needs.
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 solution effectively prevents shield layer protrusion, allowing for a reduced flying height and improved recording density and signal-to-noise ratio by managing thermal expansion and heat dissipation, thus enhancing the magnetic head's performance.
Implementation Method 1
an end face of the shield layer located in the medium facing surface protrudes due to heat generated by the coil during operation of the magnetic head
Implementation Method 2
with a gap layer disposed in between in the medium facing surface
Implementation Method 3
a coil for generating a magnetic field corresponding to data to be written on the recording medium
Implementation Method 4
a pole layer having an end face located in the medium facing surface, the pole layer allowing a magnetic flux corresponding to the magnetic field generated by the coil to pass therethrough and generating a write magnetic field
Implementation Method 5
the shield has a function of preventing a magnetic flux from reaching the recording medium, the flux being generated from the end face of the pole layer and expanding in directions except the direction perpendicular to the plane of the recording medium. The shield also has a function of returning a magnetic flux
Data Source
AI summary
A magnetic head includes a pole layer and a shield. The shield includes a shield layer having a front end face located in the medium facing surface at a position forward of an end face of the pole layer along a direction of travel of the recording medium. The magnetic head further includes a stopper layer for suppressing protrusion of the front end face of the shield layer, the stopper layer being disposed adjacent to the shield layer and made of a nonmagnetic material having a linear thermal expansion coefficient of 5×10−6/° C. or smaller at a temperature of 25° C. to 100° C.