Al2O3-TiC Substrate Lattice Control for HDD Thermal Stability
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Solution Overview
Problem
The existing substrates for thin-film magnetic heads face challenges in achieving high surface smoothness and thermal conductivity, leading to issues like thermal pole tip recession (TPTR) and unstable air flow control, which affect the recording density and capacity of hard disk drives (HDDs).
Innovation Solution
An Al2O3—TiC-based substrate is developed with specific lattice constants for the Al2O3 and TiC phases, optimized to reduce impurities and improve sintering properties, enhancing surface smoothness and thermal conductivity, thereby preventing TPTR and maintaining accurate floating height over the disk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the substrate uses conventional Al2O3—TiC ceramic sintered body, then it has good thermal property and mechanical property, but it cannot achieve high surface smoothness required for stable air flow control at low floating height
Solution Approach 1:
The patent applies parameter changes by precisely controlling the lattice constants of Al2O3 (a-axis: 4.752-4.756 Å, c-axis: 12.985-12.992 Å) and TiC (4.297-4.325 Å) phases, and adjusting their composition ratios to achieve optimal surface smoothness and thermal conductivity for stable air flow control
Solution Approach 2:
The patent uses composite materials by creating a multi-phase ceramic sintered body containing Al2O3 phase, TiC phase, and Al2TiO5 phase in specific proportions, where each phase contributes different properties: Al2O3 provides surface smoothness, TiC provides thermal conductivity, and Al2TiO5 enhances mechanical strength
2Reliability
If the substrate has high thermal conductivity, then it can prevent thermal pole tip recession (TPTR), but it becomes difficult to achieve the required surface smoothness for accurate floating height control
Solution Approach 1:
The patent applies local quality by assigning different functions to different phases within the substrate: TiC phase (30-70 wt%) provides thermal conductivity to prevent TPTR, while Al2O3 phase (20-60 wt%) provides surface smoothness, and Al2TiO5 phase (5-20 wt%) provides mechanical strength
Solution Approach 2:
The patent uses composite materials by creating a multi-phase ceramic sintered body where each phase contributes different properties: Al2O3 provides surface smoothness, TiC provides thermal conductivity, and Al2TiO5 enhances mechanical strength, achieving both thermal stability and surface precision simultaneously
3Productivity
If the floating height is reduced to increase recording density, then higher capacity is achieved, but the air flow becomes unstable due to insufficient surface smoothness
Solution Approach 1:
The patent applies parameter changes by precisely controlling the lattice constants of Al2O3 and TiC phases, and adjusting their composition ratios to achieve optimal surface smoothness and thermal conductivity for stable air flow control at low floating height
Solution Approach 2:
The patent applies pneumatic principles by optimizing the air bearing surface geometry and material properties to maintain stable air flow and floating height at reduced clearance, enabling high recording density operation
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 substrate achieves superior surface smoothness and thermal conductivity, preventing TPTR and ensuring stable operation, which contributes to increased recording density and capacity in HDDs.
Implementation Method 1
a c-axis lattice constant of an Al2O3 phase is 12.985 Å (1.2985 nm) or more and 12.992 Å (1.2992 nm) or less, and a lattice constant of a TiC phase is 4.297 Å (0.4297 nm) or more and 4.325 Å (0.4325 nm) or less
Data Source
AI summary
An AlTiC-based substrate suitable for a thin-film magnetic head is provided. The Al2O3—TiC based substrate for a thin-film magnetic head including an Al2O3 phase and a TiC phase, wherein a c-axis lattice constant of the Al2O3 phase is 12.985 Å or more and 12.992 Å or less, and a lattice constant of the TiC phase is 4.297 Å or more and 4.325 Å or less.