Glass Substrate Cleaning via Dual-Frequency Supersonic Segmentation
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Solution Overview
Problem
The challenge is to effectively remove fine abrasive particles from glass substrates for magnetic disks using a supersonic cleaning method, as high-frequency supersonic waves fail to remove particles of 20 nm size and low-frequency waves are insufficient, leading to surface irregularities and contamination issues, especially with the advancement of magnetic recording technology and the introduction of Dynamic Flying Height techniques.
Innovation Solution
A manufacturing method involving a polishing step with abrasive particles of 10 nm to 30 nm and a supersonic cleaning step with a two-stage frequency approach: a first cleaning at 300 kHz to 1,000 kHz to aggregate particles, followed by a second cleaning at 30 kHz to 100 kHz to remove the secondary particles, preventing concave defects and ensuring surface smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-frequency supersonic waves (above 100 kHz) are used for cleaning, then cleaning efficiency for larger particles improves, but fine abrasive particles of 20 nm or less aggregate and cannot be removed
Solution Approach 1:
The cleaning process is divided into two distinct stages with different frequency ranges: first cleaning (10-100 kHz) and second cleaning (100 kHz-1 MHz). This segmentation allows each stage to target different particle sizes and states, preventing aggregation in the first stage and removing aggregated particles in the second stage, thereby resolving the contradiction between cleaning efficiency and surface smoothness
Solution Approach 2:
The patent employs periodic alternation between low-frequency and high-frequency supersonic waves in sequence. The first cleaning uses low-frequency waves to prevent aggregation, followed by high-frequency waves to remove aggregated particles. This periodic action pattern enables both cleaning efficiency and surface smoothness to be achieved at different time points in the process
2Manufacturing precision
If low-frequency supersonic waves (below 100 kHz) are used for cleaning, then fine particle removal improves, but cleaning efficiency for larger particles decreases
Solution Approach 1:
The cleaning process is divided into two distinct stages with different frequency ranges: first cleaning (10-100 kHz) and second cleaning (100 kHz-1 MHz). This segmentation allows each stage to target different particle sizes and states, preventing aggregation in the first stage and removing aggregated particles in the second stage, thereby resolving the contradiction between cleaning efficiency and surface smoothness
Solution Approach 2:
The patent maintains continuous cleaning action through the sequential execution of first cleaning and second cleaning steps. The first cleaning continuously prevents particle aggregation, and the second cleaning continuously removes aggregated particles, ensuring that both fine particle removal and overall cleaning efficiency are maintained throughout the entire process without interruption
3Manufacturing precision
If abrasive particles of 10 nm to 30 nm are used for polishing, then surface smoothness improves, but particle removal difficulty increases
Solution Approach 1:
The first cleaning step using low-frequency supersonic waves (10-100 kHz) serves as a preliminary action that prevents fine abrasive particles from aggregating during the polishing process. By maintaining particles in a dispersed state before the second cleaning, the subsequent removal of these fine particles becomes significantly easier, resolving the contradiction between achieving smooth surfaces and ease of particle removal
Solution Approach 2:
The two-stage cleaning process acts as an intermediary mechanism between polishing and final surface completion. The first cleaning intermediates by preventing aggregation, and the second cleaning intermediates by removing aggregated particles, thereby facilitating the overall particle removal process while maintaining the surface smoothness achieved through fine abrasive polishing
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 method effectively removes fine abrasive particles and contaminants from glass substrates without causing concave defects, enhancing the surface smoothness and reducing the risk of head crashes, thereby supporting higher recording densities and improved magnetic disk performance.
Implementation Method 1
performing a first supersonic cleaning at a frequency to aggregate particles having the specified particle size to form secondary particles
Implementation Method 2
performing a first supersonic cleaning at a frequency to aggregate particles having the specified particle size to form secondary particles
Implementation Method 3
performing a second supersonic cleaning at a frequency to remove the secondary particles as the cleaning target
Implementation Method 4
performing a second supersonic cleaning at a frequency to remove the secondary particles as the cleaning target
Data Source
AI summary
An object of the invention is to effectively remove particles on the glass substrate surfaces, even in the case wherein abrasive particles having a small particle size is used in the polishing step of the glass substrate and a supersonic treatment is performed at a high frequency at the supersonic cleaning step after the polishing step. In a manufacturing method of a glass substrate for a magnetic disk comprising a polishing step for performing polishing of the glass substrate and a supersonic cleaning step for performing supersonic cleaning of the glass substrate after the polishing step, the polishing step uses abrasive particles having a particle size of 10 nm to 30 nm and a first supersonic cleaning is performed at a frequency of 300 kHz to 1,000 kHz to form secondary particles and then a second supersonic cleaning is performed at a frequency of 30 kHz to 100 kHz in the supersonic cleaning step.