Magnetic Head Insulating Films Prevent Coil Shorting
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Solution Overview
Problem
Magnetic heads for perpendicular magnetic recording face challenges in preventing unwanted erasure due to skew, which degrades recording density and write characteristics, and are prone to coil shorting due to the configuration of the magnetic path and insulating layers.
Innovation Solution
The magnetic head design includes a main pole with an inclined surface portion and a write shield with opposed inclined and flat portions, along with insulating films to reduce magnetic flux leakage and enhance insulation, allowing for a shorter magnetic path and preventing coil shorting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the main pole is thinned to prevent unwanted erasure, then adjacent track erasure is reduced, but overwrite property degrades due to reduced cross-sectional area for magnetic flux guidance
Solution Approach 1:
The main pole is designed with non-uniform thickness: thinned at the medium-facing surface to reduce unwanted erasure, and thicker at the rear end to maintain magnetic flux guidance capability and overwrite property. This local variation in geometry allows simultaneous optimization of both anti-erasure performance and write capability.
2Productivity
If the magnetic path is shortened to improve write characteristics, then recording density increases, but coil insulation reliability decreases due to reduced insulation layer effectiveness
Solution Approach 1:
Multiple insulating layers with different materials and properties are stacked between the coil and write shield: a first insulating layer (alumina) provides base insulation, a second insulating layer (silicon oxide) enhances insulation strength, and a third insulating layer (silicon nitride) provides additional protection. This composite insulating structure ensures reliable electrical isolation even with the shortened magnetic path configuration.
3Object-affected harmful factors
If the write shield is positioned closer to the main pole to reduce magnetic flux leakage, then unwanted erasure decreases, but insulation requirements increase due to higher risk of coil shorting
Solution Approach 1:
A multi-layer insulating structure comprising alumina, silicon oxide, and silicon nitride layers is implemented between the coil and write shield. This composite insulation system provides sufficient electrical strength to prevent coil shorting even when the write shield is positioned close to the main pole for optimal magnetic flux containment.
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 configuration effectively prevents unwanted erasure by reducing magnetic flux leakage and improving write characteristics, while also ensuring reliable operation by enhancing insulation and reducing the risk of coil shorting.
Implementation Method 1
The coil produces a magnetic field corresponding to data to be written on the recording medium
Implementation Method 2
The main pole allows a magnetic flux corresponding to the magnetic field produced by the coil to pass, and produces a write magnetic field from its end face
Data Source
AI summary
A magnetic head includes a coil, a main pole, a write shield, a first insulating film, and a second insulating film. The coil includes a specific coil element. The main pole has a top surface including an inclined surface portion and a flat surface portion. The write shield includes an inclined portion. The inclined portion includes a first portion opposed to the inclined surface portion, and a second portion located farther from a medium facing surface than the first portion. The specific coil element includes an interposition part interposed between the flat surface portion and the second portion. The first insulating film is interposed between the inclined surface portion and the first portion of the inclined portion, and between the interposition part and the second portion of the inclined portion. The second insulating film is interposed between the first insulating film and the second portion of the inclined portion.