Perpendicular Magnetic Recording Head Shield Layer Projection Control
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Solution Overview
Problem
Conventional thin-film magnetic heads with perpendicular magnetic recording schemes face challenges in maintaining a low flying height to achieve high recording density due to heat-induced protrusion of the shield layer, which leads to potential collisions with the recording medium and reduced writing characteristics.
Innovation Solution
A thin-film magnetic head design featuring a write shield layer with a front shield part connected to the opposing shield part without straddling the thin-film coil, and a shield connecting part with a tilt structure to reduce the magnetic path length and prevent shield layer projection, while maintaining a continuous magnetic circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thin-film coil is used to generate magnetic field for recording data, then the recording function is achieved, but heat is generated causing the coil-insulating layer to expand and the shield layer to protrude
Solution Approach 1:
The patent extracts the harmful function (heat generation) from the thin-film coil by introducing a heat dissipation structure. The coil heat dissipation fin extends from the coil assembly to conduct heat away from the coil and coil-insulating layer, preventing thermal expansion and shield layer protrusion while maintaining the recording function.
Solution Approach 2:
The patent introduces a heat dissipation fin as an intermediary structure between the heat source (thin-film coil) and the surrounding environment. This fin acts as a thermal conductor to transfer heat away from the critical components, resolving the contradiction between maintaining recording function and reducing heat generation effects.
2Stability of the object's composition
If the shield layer protrudes due to heat expansion, then the coil-insulating layer expansion is accommodated, but the flying height increases and collision with recording medium occurs
Solution Approach 1:
The patent extracts the expansion problem from the coil-insulating layer by providing an independent heat dissipation path through the fin structure. This allows the coil-insulating layer to maintain its dimensional stability while the fin handles the thermal management, preventing shield layer protrusion and maintaining low flying height.
Solution Approach 2:
The patent replaces the mechanical constraint approach (restricting expansion) with a thermal management approach (dissipating heat). Instead of mechanically preventing the coil-insulating layer from expanding, the fin structure thermally manages the heat source, eliminating the root cause of expansion and maintaining stable dimensional relationships.
3Productivity
If the flying height is reduced to achieve high recording density, then the recording density increases, but the risk of collision with recording medium increases
Solution Approach 1:
The patent applies preliminary thermal management action by incorporating the heat dissipation fin structure before the head operates at low flying height. This pre-cooling and continuous heat dissipation mechanism ensures that the shield layer does not protrude during operation, enabling safe operation at reduced flying heights for high recording density without increasing collision risk.
4Temperature
If the shield layer protrudes, then the thermal expansion is accommodated, but the writing characteristics deteriorate
Solution Approach 1:
The patent converts the harmful thermal expansion into a beneficial heat dissipation mechanism. The heat dissipation fin, which could be seen as an additional structure, actually benefits the system by actively removing heat, preventing the harmful effects of thermal expansion on writing characteristics, and improving overall thermal management of the recording head.
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 design effectively suppresses shield layer projection and reduces magnetic path length, enhancing recording density and preventing collisions with the recording medium, thus improving the stability and performance of the thin-film magnetic head.
Implementation Method 1
the thin-film coil 602 generates heat when electric current is passed therethrough
Implementation Method 2
the coil-insulating layer 605 is formed of an organic material such as photoresist or the like and is thus larger in expansion coefficient than the thin-film coil 602. For this reason, when heat is applied, the coil-insulating layer 605 is likely to expand.
Data Source
AI summary
A thin-film magnetic head is constructed such that a main magnetic pole layer, a write shield layer, a gap layer, and a thin-film coil are laminated on a substrate. The write shield layer has an opposing shield part opposing the main magnetic pole layer and a front shield part. The front shield part is connected to the opposing shield part without straddling the thin-film coil. Besides, the front shield part has a shield front end face disposed in the medium-opposing surface and a shield upper end face formed distanced from the medium-opposing surface. Further, the front shield part has a shield connecting part. The shield front end face is connected to the shield upper end face by the shield connecting part.