Touch Screen Panel Multilayer Connection Wire Corrosion Protection
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Solution Overview
Problem
Conventional touch screen panels face issues with wiring reliability due to corrosion and increased moisture permeability in high temperature and humidity environments, leading to potential cracks and compromised bending characteristics.
Innovation Solution
A touch screen panel design featuring a substrate with a sensing electrode and connection wire, where a passivation layer and capping layer are applied to improve metal wiring reliability, forming a T-shaped stacking structure for step coverage and lateral passivation, using different etching rates for the metal wiring and capping layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic passivation layer and capping layer are deposited at low temperatures to protect metal wirings, then corrosion protection is improved, but moisture permeability increases and stress-induced cracks may form
Solution Approach 1:
The patent applies a composite passivation structure consisting of an inorganic passivation layer (such as SiNx) and an organic passivation layer (such as parylene or polyimide). The inorganic layer provides excellent corrosion protection and low moisture permeability, while the organic layer adds additional moisture barrier protection and flexibility to reduce stress-induced cracking. This composite approach combines the advantages of both material types to achieve superior overall protection.
Solution Approach 2:
The patent introduces an organic passivation layer that acts as a flexible protective film over the rigid inorganic passivation layer. This organic layer (e.g., parylene or polyimide) provides moisture barrier protection while its flexibility helps accommodate thermal expansion differences and reduces stress concentration, preventing cracks from forming in the underlying substrate or inorganic layer during temperature cycling.
2Reliability
If thickness of capping layer and passivation layer is increased to improve protective features, then corrosion protection is improved, but stress increases causing cracks and hampering bending characteristics
Solution Approach 1:
The organic passivation layer serves as a flexible protective film that can accommodate bending and thermal expansion without transmitting excessive stress to the underlying substrate. This flexible layer provides moisture and corrosion protection while maintaining the panel's ability to bend, thus resolving the contradiction between protective thickness and bending characteristics.
Solution Approach 2:
The composite structure of rigid inorganic layer and flexible organic layer creates a multi-functional protection system where each layer contributes different properties. The inorganic layer provides dense corrosion protection, while the organic layer provides flexibility and additional moisture barrier, achieving effective protection without requiring excessive thickness that would compromise bending characteristics.
3Reliability
If T-shaped stacking structure is formed using different etching rates, then lateral passivation is improved, but manufacturing complexity increases
Solution Approach 1:
The patent utilizes the different etching rates of the metal wiring layer and capping layer as a controllable parameter to automatically form the T-shaped stacking structure during the patterning process. By carefully selecting etching conditions and materials, the structure self-organizes into the desired T-shape without requiring additional patterning steps, thus achieving lateral passivation while keeping manufacturing relatively simple.
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
Enhances the reliability of metal wirings in high temperature and humidity conditions without affecting the patterning layout, providing improved protection against corrosion and maintaining the panel's structural integrity.
Implementation Method 1
a passivation layer and capping layer are applied to improve metal wiring reliability, forming a T-shaped stacking structure for step coverage and lateral passivation
Implementation Method 2
using different etching rates for the metal wiring and capping layers
Data Source
AI summary
A touch screen panel includes a substrate, a sensing electrode, a connection wire, and a passivation layer. The substrate includes a first area and a second area disposed outside the first area. The sensing electrode is disposed in the first area. The connection wire is electrically connected to the sensing electrode, the connection wire being disposed in the second area. The passivation layer covers portions of the sensing electrode and the connection wire. The sensing electrode includes a first conductive layer disposed on the substrate. The connection wire includes a second conductive layer disposed on the substrate, a metal wiring layer disposed on the second conductive layer, and a capping layer disposed on the second conductive layer.