Hard Disk Substrate with NiP Plating for Wobble Reduction
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Solution Overview
Problem
Thinner Al alloy substrates in hard disk devices suffer from wobbling (fluttering) and decreased bearing strength, leading to surface scratches when in contact with magnetic heads due to drop impacts.
Innovation Solution
A hard disk substrate with an aluminum alloy substrate coated with NiP plating films, achieving a Vickers hardness of 60 Hv or more, a plating thickness ratio of 3.8% or more, and a Young's modulus of 74.6 GPa or more, with a thickness of 0.338 mm to 0.635 mm and plating thickness of 22 μm to 60 μm, to enhance impact resistance and reduce fluttering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the hard disk substrate thickness is reduced to increase device capacity, then the number of hard disks that can be loaded increases, but the substrate experiences increased wobbling and decreased bearing strength
Solution Approach 1:
The patent applies composite material structure by combining aluminum alloy substrate with NiP plating films to create a multi-layer composite structure. This composite construction enhances the bearing strength and surface hardness of the thin substrate, allowing it to maintain structural integrity despite reduced thickness. The NiP plating layer provides additional mechanical strength and wear resistance, resolving the contradiction between thinning the substrate for higher capacity and maintaining sufficient bearing strength.
2Quantity of substance
If the hard disk substrate thickness is reduced to increase device capacity, then the number of hard disks that can be loaded increases, but the substrate experiences increased wobbling during rotation
Solution Approach 1:
The composite material structure of aluminum alloy substrate combined with NiP plating films provides enhanced rigidity and dimensional stability. The multi-layer composite construction reduces rotational wobbling by improving the overall structural integrity of the thin substrate, enabling it to maintain stable rotation despite reduced thickness.
3Strength
If the substrate hardness is reduced due to thinning, then the substrate becomes more flexible, but the surface easily develops scratches upon contact with magnetic head
Solution Approach 1:
The patent applies local quality principle by providing different properties to different parts of the substrate structure. The aluminum alloy substrate maintains its inherent flexibility, while the NiP plating films on the surface provide enhanced hardness and scratch resistance. This localized differentiation of material properties allows the substrate to be both flexible and scratch-resistant simultaneously.
Solution Approach 2:
The composite material structure combines materials with complementary properties: aluminum alloy for flexibility and NiP plating for surface hardness. This composite construction resolves the contradiction between substrate flexibility and surface scratch resistance by allowing each material to contribute its optimal properties to the overall structure.
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 effectively reduces surface scratches and amplitude due to fluttering, improving bearing strength and collision resistance during rotation, thereby enhancing the reliability and capacity of hard disk devices.
Implementation Method 1
an aluminum alloy substrate having NiP plating films on the surfaces
Implementation Method 2
a Young's modulus of the hard disk substrate is 74.6 GPa or more
Data Source
AI summary
Provided are a thin hard disk substrate that is scratch-resistant on the disk surface and wobbles less during rotation and a hard disk device including such a hard disk substrate. The hard disk substrate 1 includes an aluminum alloy substrate 2 having NiP plating films 3 on the surfaces. The aluminum alloy substrate 2 has the Vickers hardness of 60 Hv or more, the ratio between the thickness of the NiP plating films 3 and the thickness of the Al alloy substrate 2 is 3.8% or more, the Young's modulus of the hard disk substrate 1 is 74.6 GPa or more, and the Vickers hardness of the hard disk substrate 1 is 293 Hv or more.