Magnetic Recording Medium Surface Roughness Control
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Solution Overview
Problem
Magnetic recording media face challenges in achieving both good recording and reproducing properties and low high-speed friction, as smoothing the tape surface to improve recording properties tends to increase friction, and existing solutions struggle to balance these requirements effectively.
Innovation Solution
A magnetic recording medium with a flexible nonmagnetic base substance, a crystal control layer, and a magnetic layer, featuring a recording surface with an average surface roughness of 3.0 nm or less, a specific number of projections with heights of 7.5 nm or more, and no or limited projections with heights of 15 nm or more, optimized through a sputtering method to balance recording performance and friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the magnetic tape surface is smoothed to improve recording and reproducing properties, then recording and reproducing properties are improved, but friction increases
Solution Approach 1:
The invention applies local quality by creating specific projection structures (peaks and valleys) on the tape surface rather than uniform smoothing. The surface has controlled roughness with specific projection height distributions (256 or more projections ≥7.5nm, 0-104 projections ≥15nm per 30μm unit region), providing locally varied surface characteristics that simultaneously enable good recording contact and reduced friction through the valley regions.
Solution Approach 2:
The invention changes the surface parameter from uniform smoothness to controlled roughness with specific statistical characteristics. By controlling the average surface roughness SRa to 3.0nm or less while maintaining specific projection height distributions, the invention transforms the surface topology to achieve both good recording properties and reduced high-speed friction compared to conventional smooth surfaces.
2Manufacturing precision
If the surface is smoothed to achieve good recording properties, then recording properties are improved, but high-speed friction increases
Solution Approach 1:
The invention creates local quality variations on the tape surface with specific projection height distributions. The controlled roughness pattern (256+ projections ≥7.5nm, 0-104 projections ≥15nm per 30μm region) provides local contact points for recording while valley regions reduce friction during high-speed operation, achieving both precision and low friction.
Solution Approach 2:
Instead of smoothing the surface to improve recording properties (conventional approach), the invention inverts the approach by controlling the surface to have specific roughness characteristics with defined projection height distributions. This inverted strategy achieves good recording properties through controlled irregularities rather than uniform smoothness, simultaneously reducing high-speed friction.
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 solution enables both excellent recording and reproducing properties and reduced high-speed friction, enhancing the magnetic recording medium's performance and reliability by carefully controlling surface roughness and projection counts.
Implementation Method 1
a magnetic recording medium in which a plurality of thin films are formed on a nonmagnetic base material by a sputtering method
Data Source
AI summary
A magnetic recording medium has a recording surface having an average surface roughness SRa of 3.0 nm or less, the number of projections having a height of 7.5 nm or more included in a unit region (where the unit region is a square region with each side having a length of 30 μm) of the recording surface is 256 or more, and the number of projections having a height of 15 nm or more included in the unit region of the recording surface is 0 or more and 104 or less.