Fluid Dynamic Bearing Oil Composition for HDD Volatile Adhesion Control
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Solution Overview
Problem
The volatilization of lubricant components in hard disk drives (HDDs) leads to adhesion on magnetic disks or heads, causing read/write errors, which are difficult to prevent even with low-volatile base oils due to increased recording densities and internal pressures.
Innovation Solution
A fluid dynamic pressure bearing oil containing aliphatic monoester or diester compounds with specific alkyl chain lengths is used to minimize adhesion, even when volatilized, by incorporating additives that reduce adhesion to magnetic disks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low-volatile base oil is selected to suppress volatilization, then the volatilization amount is reduced, but complete elimination of volatilization is difficult and read/write errors still occur due to adhesion of volatile components
Solution Approach 1:
The patent introduces a specific ester compound as an intermediary substance that modifies the properties of the lubricant. This ester compound acts as a mediator between the base oil and the magnetic disk surface, preventing direct adhesion of volatile components to the disk while maintaining the lubrication function. The ester compound with specific molecular weight and structure serves as a protective intermediary layer.
Solution Approach 2:
The patent changes the chemical and physical parameters of the lubricant by selecting an ester compound with specific molecular weight (500-5000) and structural parameters. This parameter optimization ensures that the lubricant has appropriate volatility, adhesion properties, and lubrication performance, resolving the contradiction between suppressing volatilization and preventing adhesion.
2Quantity of substance
If recording density is increased to improve storage capacity, then more data can be stored, but internal pressure increases and volatilization of lubricant components worsens
Solution Approach 1:
The patent optimizes the molecular weight parameter of the ester compound (500-5000 range) to balance volatility and lubrication performance. This parameter change allows the lubricant to maintain stability under increased internal pressure from high-density recording while minimizing volatilization losses.
Solution Approach 2:
The patent creates a composite lubricant system combining base oil with specific ester compounds. This composite material approach allows the lubricant to withstand the increased internal pressure from high recording density while the ester compound specifically addresses the volatilization issue through its molecular structure.
Data Source
AI summary
ObjectTo provide a fluid dynamic pressure bearing oil and a fluid dynamic pressure bearing filled with the fluid dynamic pressure bearing oil, and to provide a spindle motor and a disk drive device including the spindle motor in which the fluid dynamic pressure bearing oil and the bearing are used, thereby suppressing adhesion of a volatile component to a magnetic disk or the like even when the fluid dynamic pressure bearing oil is volatilized, so that occurrence of HDD read/write errors can be suppressed.SolutionA fluid dynamic pressure bearing oil contains at least one compound selected from the group consisting of a monoester compound represented by the following Formula (1) and a diester compound represented by the following Formula (2): R1—C(═O)O—R2 (1) (where R1 is an alkyl group having 10 or more carbon atoms in total, R2 is an alkyl group having 9 or more carbon atoms in total, and R3-E1-R4-E2-R5 (2) (where R3 and R5 are each independently an alkyl group having 8 or more carbon atoms in total, R4 is an alkylene group having 4 or more carbon atoms in total, and E1 and E2 are each independently —C(═O)O— or —OC(═O)—.