Phosphoric Acid-Free Etchant for Fine Silver Wiring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing etchant compositions for flat panel display devices, particularly those using phosphoric acid, are unsuitable for forming fine and complicated wiring patterns due to high viscosity, which can damage substrates and lead to over-etching, and they react with metal electrodes, causing defects in the wiring structure.
Innovation Solution
A phosphoric acid-free etchant composition comprising 40 wt % to 60 wt % organic acid, 6 wt % to 12 wt % glycol compound, 1 wt % to 10 wt % nitric acid or sulfuric acid, 1 wt % to 10 wt % nitrate salt compound, and water, specifically designed to etch silver or silver alloys without reacting with metal electrodes, thereby preventing over-etching and ensuring stable electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If phosphoric acid-based etchant composition is used, then etching capability is improved, but viscosity increases causing substrate damage and over-etching
Solution Approach 1:
The patent changes the chemical composition parameters of the etchant by replacing phosphoric acid with organic acid compounds (acetic acid, formic acid, propionic acid, butyric acid, or their mixtures) at concentrations of 5-50 wt%. This parameter change reduces the viscosity and harmful effects on substrates while maintaining effective etching capability for silver and silver alloy layers.
Solution Approach 2:
The patent employs a disposable etchant composition formulation that can be used without extensive purification or regeneration. The organic acid-based etchant is designed to be used and then discarded after a certain number of cycles, eliminating the need for complex recovery systems and reducing overall process cost while avoiding substrate damage associated with phosphoric acid.
2Productivity
If phosphoric acid-based etchant composition is used, then etching power is improved, but selectivity deteriorates causing reaction with metal electrodes
Solution Approach 1:
The patent achieves local quality by creating an etchant with selective reactivity - the organic acid-based composition is specifically tailored to etch silver and silver alloys effectively while being non-reactive toward other metal electrodes such as aluminum, copper, and their alloys. This selective action allows different regions (silver wiring vs. other electrodes) to be treated differently by the same etchant solution.
Solution Approach 2:
The patent uses a composite etchant formulation consisting of multiple organic acid compounds (acetic acid, formic acid, propionic acid, butyric acid) in specific combinations and concentrations. This composite approach provides both sufficient etching power for silver (maintaining high productivity) and selective action that prevents unwanted reactions with other metal electrodes (maintaining pattern precision).
3Manufacturing precision
If phosphoric acid-based etchant composition is used, then etching capability is improved, but process complexity increases due to over-etching control
Solution Approach 1:
The organic acid-based etchant composition is designed to self-regulate the etching process through its inherent chemical properties. The etchant naturally stops etching when the silver layer is completely removed without attacking the underlying substrate or other electrodes, eliminating the need for complex monitoring and control systems to prevent over-etching.
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 etchant composition effectively forms fine and complicated wiring patterns with reduced viscosity, preventing substrate damage and ensuring stable electrical connections by selectively etching silver or silver alloys without affecting indium oxide layers or metal electrodes, thus reducing process costs and improving etching efficiency.
Implementation Method 1
etch the thin film in a predetermined wiring shape using the etchant composition
Implementation Method 2
about 1 wt % to about 10 wt % of nitric acid, sulfuric acid, or hydrochloric acid
Data Source
AI summary
A phosphoric acid-free etchant composition and a method of forming a wiring, the composition including about 40 wt % to about 60 wt % of an organic acid compound; about 6 wt % to about 12 wt % of a glycol compound; about 1 wt % to about 10 wt % of nitric acid, sulfuric acid, or hydrochloric acid; about 1 wt % to about 10 wt % of a nitrate salt compound; and water, all wt % being based on a total weight of the phosphoric acid-free etchant composition.