Electrostatic Inkjet Trench Filling for Display Conductive Patterns
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Solution Overview
Problem
Existing methods for forming thick conductive signal lines in display devices face challenges such as increased substrate stress, warping, and difficulty in achieving complex patterns, leading to reliability issues and RC delay due to high resistance.
Innovation Solution
The method involves forming a trench on a substrate and using an electrostatic injection of conductive ink, with carefully controlled voltages applied to the nozzle and substrate to generate an electric field, allowing for the precise deposition of fine droplets with sizes less than 100 nanometers, effectively filling deep trenches and increasing the thickness of the conductive pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the signal line is increased to reduce resistance, then RC delay is prevented, but the aperture ratio decreases
Solution Approach 1:
The patent transitions from planar (2D) signal line formation to three-dimensional (3D) trench filling. By forming trenches with depth and then filling them with conductive material, the signal line gains a vertical dimension, allowing increased thickness without proportionally increasing the horizontal area occupied, thus maintaining aperture ratio while reducing resistance.
Solution Approach 2:
The patent utilizes conductive ink materials that can be deposited in a controlled manner to fill trench structures. The ink formulation allows for precise deposition and curing to form thick, low-resistance conductive patterns within the trench geometry.
2Reliability
If sputtering is used to form thick signal lines, then resistance is reduced, but substrate stress increases causing warping
Solution Approach 1:
The patent replaces the physical sputtering process (which applies mechanical stress through ion bombardment and material deposition) with a chemical/electrostatic inkjet printing process. The conductive ink is deposited through electrostatic attraction and capillary action into trenches, eliminating the high-stress mechanical deposition mechanism while achieving comparable or superior conductive pattern formation.
Solution Approach 2:
The patent performs preliminary trench formation before depositing the conductive material. By pre-forming the trench structure with appropriate depth and geometry, the subsequent ink deposition is guided into the trench, ensuring uniform thick pattern formation without requiring high-stress deposition processes.
3Reliability
If electroless plating is used to form thick signal lines, then low resistance is achieved, but additional seed layer processes are required increasing complexity
Solution Approach 1:
The patent extracts and eliminates the seed layer formation step from the electroless plating process. By using direct inkjet printing of conductive ink, the patent removes the intermediate seed layer requirement, reducing the number of process steps while still achieving thick, low-resistance signal lines through direct deposition of conductive material into trenches.
Solution Approach 2:
The patent uses a disposable conductive ink formulation that can be directly printed and cured to form the final conductive pattern. This eliminates the need for reusable seed layers and complex plating baths, simplifying the overall process while achieving the desired electrical performance.
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 improves manufacturing reliability by reducing resistance and preventing RC delay, enabling the formation of thick conductive patterns with enhanced precision and reduced substrate stress.
Implementation Method 1
providing a conductive ink to the trench while an electric field is generated between the substrate and a nozzle which injects the conductive ink
Implementation Method 2
an electric field is generated between the substrate and a nozzle which injects the conductive ink
Implementation Method 3
providing a conductive ink to the trench while an electric field is generated between the substrate and a nozzle which injects the conductive ink
Data Source
AI summary
A method of forming a conductive pattern includes forming a trench on a substrate, and providing a conductive ink to the trench while an electric field is generated between the substrate and a nozzle which ejects the conductive ink.