Glass Substrate Cleaning via Si-Elution Liquid Treatment
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Solution Overview
Problem
Conventional methods for fabricating glass substrates for magnetic disks face challenges in removing abrasive and foreign matter after polishing, leading to compromised surface smoothness and magnetic recording characteristics, and are often complex and productivity-lowering.
Innovation Solution
A method involving keeping the glass substrate surface in contact with a liquid containing a Si element elution within a specific range (100 to 10,000 ppb/mm²) before scrub-cleaning, which allows for effective removal of abrasive and foreign matter while preventing re-adhesion during drying, simplifying the cleaning process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polishing is performed with abrasive to make the surface smooth, then surface smoothness is improved, but abrasive firmly adheres to the surface making removal difficult
Solution Approach 1:
The patent applies preliminary action by performing a specific treatment with a liquid containing HF acid before the scrubbing step. This preliminary chemical treatment modifies the glass substrate surface properties to prevent abrasive adhesion during the subsequent mechanical scrubbing process, thereby resolving the contradiction between achieving surface smoothness through polishing and removing the firmly adhered abrasive.
2Manufacturing precision
If multiple cleaning steps are performed to remove abrasive, then removal effectiveness is improved, but process complexity increases and productivity decreases
Solution Approach 1:
The patent uses preliminary action by applying a specific liquid treatment before scrubbing, which prepares the surface to be easily cleaned in a single scrubbing step. This eliminates the need for multiple sequential cleaning steps (such as ultrasonic cleaning, detergent cleaning, and water rinsing), thereby maintaining high cleanliness while reducing process complexity and improving productivity.
Solution Approach 2:
The patent applies parameter changes by modifying the chemical composition parameters of the cleaning liquid (using HF acid at specific concentrations) to optimize the cleaning process. This chemical parameter modification enables effective abrasive removal in a single scrubbing step rather than requiring multiple mechanical and chemical cleaning stages, thus improving productivity while maintaining surface cleanliness.
3Quantity of substance
If distance between magnetic head and disk surface is reduced to increase recording capacity, then recording capacity is improved, but risk of head collision with projections or foreign matter increases
Solution Approach 1:
The patent applies preliminary action by performing the liquid treatment and scrubbing process before magnetic recording layer formation. This preliminary cleaning ensures that the glass substrate surface is free of projections and foreign matter, creating a safe operating environment that allows reduction of the head-disk distance to increase recording capacity without risking head collision.
Solution Approach 2:
The patent uses hydraulic principles by employing liquid-based cleaning methods (HF acid solution treatment and liquid scrubbing) to remove contaminants from the glass substrate surface. This hydraulic cleaning approach effectively eliminates foreign matter and projections that could cause head collision, thereby enabling safer operation at reduced head-disk distances for higher recording capacity.
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
This approach ensures a clean and smooth glass substrate surface, enhancing magnetic recording capacity by reducing the distance between the magnetic head and disk, and simplifies the fabrication process without complicating the cleaning step.
Implementation Method 1
keeping the surface of the glass substrate in contact with a liquid having a Si element elution in the range from 100 to 10 000 ppb/mm2 before the step of cleaning by scrubbing
Data Source
AI summary
A method for fabricating a glass substrate containing SiO2 as a main ingredient thereof for an information recording medium which ensures removal of abrasive or foreign mater adhered to the glass substrate without complicating a cleaning step, involves, after a polishing step, keeping the surface of the glass substrate in contact with a liquid having a Si element elution in a range from 100 to 10 000 ppb/mm2 before a scrub-cleaning step.