Al2O3-TiC Substrate Lattice Control for Magnetic Head Sliders
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Solution Overview
Problem
The existing substrates for thin-film magnetic heads face challenges in achieving high productivity and smoothness of the lapping worked surface due to differences in hardness between the Al2O3 and TiC phases, leading to unstable air flow control and reduced recording density in hard disk drives.
Innovation Solution
An Al2O3—TiC based substrate with specific lattice constant ranges for the Al2O3 and TiC phases is developed, enhancing cutting workability and lapping rate, and reducing surface roughness, thereby improving the shape accuracy and productivity of the magnetic head slider.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an Al2O3—TiC based substrate is used for thin-film magnetic heads, then thermal property and mechanical property are improved, but cutting workability and lapping rate deteriorate due to hardness differences between phases
Solution Approach 1:
The invention changes the microstructural parameters of the Al2O3—TiC composite substrate by controlling the average grain size of Al2O3 phase to 0.5 μm or less and the average particle size of TiC phase to 0.3 μm or less. This parameter optimization resolves the contradiction by achieving both high mechanical strength and improved cutting workability/lapping rate, as the fine-grained structure reduces hardness differences between phases while maintaining mechanical properties.
Solution Approach 2:
The invention uses an Al2O3—TiC composite material system where the two phases are carefully controlled in terms of size, distribution, and volume ratio. By optimizing the composite structure with specific grain size ranges and phase distributions, the invention achieves synergistic effects that simultaneously provide high mechanical strength and improved processability during cutting and lapping operations.
2Strength
If an Al2O3—TiC based substrate is used for thin-film magnetic heads, then thermal property and mechanical property are improved, but surface roughness after lapping increases
Solution Approach 1:
The invention optimizes microstructural parameters by controlling Al2O3 grain size to 0.5 μm or less and TiC particle size to 0.3 μm or less, with specific volume ratios (TiC: 20-40 vol%). This fine-grained composite structure minimizes surface roughness after lapping while maintaining high mechanical strength, as the uniform fine structure reduces surface irregularities.
Solution Approach 2:
The invention achieves uniform local distribution of Al2O3 and TiC phases with controlled size and spacing. This local uniformity in the composite structure ensures consistent lapping behavior across the substrate surface, reducing surface roughness while maintaining overall mechanical strength through the distributed reinforcement of TiC particles.
3Manufacturing precision
If the base portion is worked to be flat via lapping, then surface flatness is improved, but productivity decreases due to low lapping rate
Solution Approach 1:
The invention changes the substrate's microstructural parameters by reducing Al2O3 grain size to 0.5 μm or less and TiC particle size to 0.3 μm or less. This optimization reduces the substrate's resistance to lapping, thereby increasing lapping rate and productivity while still achieving the required surface flatness for magnetic head operation.
Solution Approach 2:
The invention uses an optimized Al2O3—TiC composite material with specific phase distributions and size ranges that enhance lapping rate. The composite structure is designed to facilitate material removal during lapping while maintaining surface flatness, resolving the contradiction between productivity and manufacturing precision.
4Quantity of substance
If recording density is increased to 750 Gbit/square inch, then storage capacity is improved, but gap control precision between transducer and disk becomes more critical
Solution Approach 1:
The invention optimizes the substrate's microstructural parameters (Al2O3 grain size ≤0.5 μm, TiC particle size ≤0.3 μm) to achieve superior surface flatness and reduced surface roughness. This enables more precise control of the gap between transducer and disk, which is critical for maintaining high recording density of 750 Gbit/square inch and above.
Solution Approach 2:
The invention replaces reliance on mechanical lapping processes with a microstructurally optimized substrate that inherently provides the required surface quality. This substitution reduces variability in gap control and improves precision for high-density recording applications.
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 12.992 Å or more and 12.998 Å or less, and a lattice constant of the TiC phase is 4.297 Å or more and 4.315 Å or less.