Thin Film Magnetic Head Thermal Expansion Layer Design
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Solution Overview
Problem
Existing thin film magnetic heads face challenges in suppressing thermal protrusion due to ambient temperature environments, with existing solutions either compromising heat dissipation properties or risking etching of magnetic layers during manufacturing.
Innovation Solution
A thin film magnetic head design incorporating a main magnetic pole layer, return yoke layer, intermediate protective layer, and thermal expansion suppressing layer, where the thermal expansion suppressing layer is positioned on the intermediate protective layer and in contact with the return yoke layer, allowing for effective heat dissipation and protection during etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal expansion suppressing layer is disposed directly on a magnetic layer to suppress thermal protrusion, then thermal protrusion is suppressed, but the magnetic layer may be etched during manufacturing
Solution Approach 1:
An intermediate protective layer is introduced between the thermal expansion suppressing layer and the magnetic layer. This intermediate layer serves as a protective barrier during etching processes, preventing the etching solution from contacting and damaging the magnetic layer, while still allowing the thermal expansion suppressing layer to function effectively
Solution Approach 2:
The protective structure is divided into multiple functional layers: the thermal expansion suppressing layer, the intermediate protective layer, and the magnetic layer. This segmentation allows each layer to perform its specific function independently - the intermediate layer protects during manufacturing while the thermal expansion layer suppresses thermal protrusion during operation
2Temperature
If a heat dissipating layer is disposed around a thin film coil to improve heat dissipation, then heat dissipation is improved, but the volume of the heat dissipating layer is limited and the effect is not high
Solution Approach 1:
The thermal expansion suppressing layer with high thermal conductivity is applied locally to the magnetic layer and coil structures where heat generation occurs. This targeted approach provides effective heat dissipation at the heat source without requiring a large volume of heat dissipating material throughout the entire head structure
Solution Approach 2:
The patent uses composite material structures combining the thermal expansion suppressing layer with the magnetic layer and intermediate protective layer. The thermal expansion suppressing layer is made of materials with high thermal conductivity to enhance heat dissipation efficiency within the limited volume available in the thin film magnetic head structure
3Power
If large current is passed to generate stronger write magnetic field, then write capability is improved, but thermal protrusion occurs
Solution Approach 1:
The thermal expansion suppressing layer, which has high thermal conductivity, converts the harmful thermal effect of large write currents into a beneficial heat dissipation mechanism. The layer rapidly conducts heat away from the coil and magnetic layer, allowing higher write currents to be used without causing thermal protrusion
Solution Approach 2:
By introducing the thermal expansion suppressing layer with specific thermal and mechanical properties, the thermal management parameters of the magnetic head are changed. This allows the operating current parameters to be increased for better write capability while maintaining reliability through improved heat dissipation
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 limits the shift of magnetic layers towards the air bearing surface, suppresses thermal protrusion, and maintains high heat dissipation properties, stabilizing magnetic spacing and enhancing reliability.
Implementation Method 1
a thermal expansion suppressing layer containing a material having a smaller coefficient of thermal expansion and a larger thermal conductivity than the etching stop layer
Implementation Method 2
suppress the occurrence of thermal protrusion
Implementation Method 3
a main magnetic pole layer extending in a direction to intersect with an air bearing surface opposed to a recording medium and conducting a magnetic flux to the recording medium so that the recording medium is magnetized in a direction orthogonal to a surface
Implementation Method 4
The intermediate protective layer is partially disposed on the return yoke layer
Data Source
AI summary
A thin film magnetic head includes a main magnetic pole layer conducting a magnetic flux to the recording medium so that the recording medium an be magnetized in a direction orthogonal to a surface thereof; a return yoke layer disposed on a trailing side of the main magnetic pole layer; an intermediate protective layer partially disposed on a magnetic shield layer; and a thermal expansion suppressing layer having an edge located on the intermediate protective layer and being in contact with the return yoke layer in an area where the intermediate protective layer is not formed. If the thin film magnetic head is affected by ambient temperature environment, the thermal expansion suppressing layer suppresses the shift of the main magnetic pole layer and the return yoke layer toward the air bearing surface. This suppresses thermal protrusion from occurring on the thin film magnetic head due to ambient temperature environment.