Multi-Acid Etching Solution for Glass Substrate Thickness Control
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Solution Overview
Problem
The existing etching solutions for glass substrates in flat panel display manufacturing have issues with controlling etching rates, dissolving silicates, and producing excessive hydrofluoric acid, leading to uncontrolled substrate thickness and lower non-defective ratios due to impurity attachment.
Innovation Solution
An etching solution comprising 10-30 wt% phosphoric acid, 2-20 wt% nitric acid, 6-18 wt% hydrofluoric acid, 5-10 wt% hydrochloric acid, and an anionic surfactant, which is applied to the glass substrate to effectively dissolve impurities and control thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional etching solutions are used to achieve faster etching rate, then the etching speed is improved, but the etching amount becomes difficult to control and substrate thickness cannot be well controlled
Solution Approach 1:
The patent modifies the chemical composition parameters of the etching solution by incorporating specific concentrations of phosphoric acid (10-30 wt%), nitric acid (2-20 wt%), hydrofluoric acid (6-18 wt%), and hydrochloric acid (5-10 wt%). This multi-component acid system with controlled ratios achieves both high etching rate and precise thickness control by balancing the reactivity and buffering capacity of different acids.
Solution Approach 2:
The patent creates a composite etching solution system combining four different acids rather than using a single acid or simple mixture. This composite chemical system leverages the synergistic effects of phosphoric acid (buffering), nitric acid (oxidation), hydrofluoric acid (silicate dissolution), and hydrochloric acid (aqua regia formation with nitric acid) to simultaneously achieve fast etching and precise control.
2Productivity
If conventional etching solutions are used to increase etching efficiency, then the processing speed is improved, but excessive hydrofluoric acid is produced leading to uncontrolled etching
Solution Approach 1:
The patent converts the potentially harmful excessive hydrofluoric acid production into a beneficial controlled process by using phosphoric acid as a buffering agent. The phosphoric acid system controls the ionization and release of hydrofluoric acid, transforming the harmful uncontrolled HF generation into a controlled, beneficial etching process that maintains high efficiency without excessive HF production.
Solution Approach 2:
The patent introduces phosphoric acid as an intermediary substance that mediates between the hydrofluoric acid and the substrate. The phosphoric acid buffer system regulates the release and activity of hydrofluoric acid, acting as a controlling intermediary that prevents excessive HF production while maintaining effective etching rates.
3Device complexity
If simple etching solutions are used to reduce cost, then the composition simplicity is improved, but the ability to dissolve silicates is insufficient
Solution Approach 1:
The patent applies local quality by assigning specific functional roles to different acid components based on their chemical properties. Nitric acid and hydrochloric acid specifically target silicate dissolution through aqua regia formation, while phosphoric acid provides buffering and hydrofluoric acid delivers the primary etching action. Each component has its localized function optimized for its specific purpose.
Solution Approach 2:
The patent utilizes nitric acid and hydrochloric acid to form aqua regia, a powerful oxidizing mixture that dramatically enhances the ability to dissolve silicates. This strong oxidant system accelerates the breakdown of silicate structures, providing reliable silicate dissolution capability that simple etching solutions cannot achieve.
4Ease of manufacture
If physical polishing process is used to thin the substrate, then the equipment investment is reduced, but the thinning time becomes longer and precision is un-controllable
Solution Approach 1:
The patent replaces the mechanical polishing system with a chemical etching system. Instead of using mechanical abrasion with polishing powders, the invention uses a chemically active solution that dissolves the substrate material through chemical reactions. This substitution eliminates the need for complex mechanical polishing equipment while dramatically reducing processing time and improving precision control.
5Ease of manufacture
If physical polishing process is used for substrate thinning, then the equipment cost is reduced, but the non-defective ratio becomes lower
Solution Approach 1:
The patent replaces mechanical polishing with chemical etching, which inherently produces fewer defects. The chemical process creates a more uniform material removal pattern without the mechanical stresses, scratches, and contamination associated with polishing powders and mechanical contact, thereby improving the non-defective ratio while maintaining equipment cost effectiveness.
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 achieves improved non-defective ratios and controlled substrate thickness by maintaining F ion activity, dissolving silicates, and preventing excessive hydrofluoric acid production, while ensuring effective removal of impurities and maintaining substrate glossiness.
Implementation Method 1
the F ion activity may be maintained by using the three-step ionization effect of phosphoric acid
Implementation Method 2
By using nitric acid, silicate can be kept in a dissolving state by providing nitrate ions
Implementation Method 3
By using hydrofluoric acid, F ions can be provided to afford an acid solution generally with a thinning effect
Implementation Method 4
By using hydrochloric acid, in combination of the above nitric acid, the acid solution possesses the property of aqua regia, which may dissolve silicate
Implementation Method 5
In one more preferable embodiment, the etching solution can comprise an anionic surfactant
Data Source
AI summary
The invention provides an etching solution, comprising: 10 to 30 wt % of phosphoric acid; 2 to 20 wt % of nitric acid; 6 to 18 wt % of hydrofluoric acid; 5 to 10 wt % of hydrochloric acid; and water, wherein the weight percentages are based on the weight of the etching solution. The etching solution can be used for thinning the substrate in large-scale production, dissolving the precipitated impurities attached to the surface of the substrate after substrate thinning so as to remove effectively the impurities on the surface of the substrate, improve the qualified ratio and passed ratio of a product, and at the same time, provide the effective insurance for controlling the thickness of the substrate.