Magnetic Head Basecoat and Overcoat Thermal Protrusion Control
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Solution Overview
Problem
Heater-based actuation in magnetic recording heads poses challenges in balancing reliability with increased areal density, as it requires optimizing the fly height and thermal clearance while minimizing zero-heat clearance, which is not effectively addressed by existing technologies.
Innovation Solution
A magnetic head design featuring a slider with a transducer having a substrate, basecoat, and overcoat made of materials with Young's modulus and thermal expansion coefficients less than alumina, allowing for reduced thermal pole tip protrusion and lower transducer temperatures, thereby enabling lower passive fly heights with maintained reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If heater-based actuation is used to reduce fly height for increased areal density, then areal density is improved, but transducer temperature increases violating reliability limits
Solution Approach 1:
The patent changes the material parameters of the basecoat and overcoat layers, specifically selecting materials with lower thermal conductivity and appropriate thermal expansion coefficients compared to traditional alumina. This modifies the thermal field distribution within the transducer, reducing peak temperatures at the pole tip while maintaining the structural integrity and enabling heater-based actuation for increased areal density.
Solution Approach 2:
The patent employs composite material structures with multiple layers (basecoat and overcoat) having different thermal and mechanical properties. The basecoat uses a material with lower thermal conductivity to reduce heat transfer to the pole tip, while the overcoat provides mechanical protection. This composite approach allows optimization of both thermal management and structural requirements simultaneously.
2Strength
If alumina is used for basecoat and overcoat, then mechanical strength is maintained, but thermal pole tip protrusion is excessive
Solution Approach 1:
The patent modifies the thermal conductivity parameter of the coating materials by replacing alumina with materials having lower thermal conductivity. This parameter change reduces the thermal pole tip protrusion while the mechanical strength is maintained through careful selection of materials with appropriate Young's modulus and fracture toughness properties.
Solution Approach 2:
The patent applies different material properties to different layers of the coating structure. The basecoat layer uses a material optimized for thermal management with lower thermal conductivity, while the overcoat layer provides mechanical protection. This local differentiation of material quality allows simultaneous optimization of thermal and mechanical performance.
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 design achieves lower thermal pole tip protrusion and reduced transducer temperatures, allowing for lower passive fly heights and reduced heater power requirements, enhancing reliability and efficiency in achieving increased areal density.
Implementation Method 1
a basecoat positioned adjacent the substrate, wherein the basecoat includes a material having a Young's modulus that is less than that of alumina and a coefficient of thermal expansion that is less than that of alumina
Data Source
AI summary
A magnetic head that includes: a slider having a leading edge and a trailing edge; and a transducer, the transducer formed on the trailing edge of the slider and the transducer including: a substrate; a basecoat positioned adjacent the substrate, wherein the basecoat includes a material having a Young's modulus that is less than that of alumina and a coefficient of thermal expansion that is less than that of alumina; a reader; a writer; a heater; and an overcoat encasing at least a portion of the transducer, wherein the overcoat includes a material having a Young's modulus that is less than that of alumina and a coefficient of thermal expansion that is less than that of alumina.