Capacitive Touch Sensor Electrode Formation via Deep UV Laser Scribing
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Solution Overview
Problem
Existing methods for forming capacitive touch sensor electrodes on glass substrates are complex and prone to defects, especially when using laser ablation, which risks damaging underlying layers due to the narrow window between effective ablation and damage thresholds.
Innovation Solution
Employing a pulsed laser operating in the deep ultra-violet range with pulse lengths less than 50ns, specifically at wavelengths like 266nm, to directly scribe grooves in the transparent conductive layer without damaging the RGB, BM, or organic layers, thereby forming electrode structures efficiently and accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If standard laser ablation is used to form electrode patterns in the transparent conductive layer, then the electrode structures can be formed efficiently, but the underlying layers (RGB, BM, organic layers) are at risk of thermal damage
Solution Approach 1:
The patent applies parameter changes by selecting a specific laser wavelength (266nm deep UV) and pulse duration (<50ns) that creates a narrow processing window. This specific parameter combination enables ablation of the transparent conductive layer while minimizing thermal diffusion to underlying layers, thus resolving the contradiction between efficient electrode formation and preventing thermal damage.
Solution Approach 2:
The patent employs periodic pulsed laser action with durations less than 50ns. The pulsed nature of the laser delivers energy in short bursts, allowing the material to ablate before significant thermal diffusion occurs. This periodic action enables efficient material removal while protecting underlying sensitive layers from thermal damage.
2Manufacturing precision
If multi-step lithographic processes are used to form electrode patterns, then the electrode structures can be formed with good precision, but the process complexity increases and defects are more likely
Solution Approach 1:
The patent extracts the pattern formation step from the complex multi-step lithographic process and replaces it with direct laser ablation. By removing the resist coating, exposure, and chemical etching steps, the process complexity is reduced while maintaining or improving pattern precision through direct digital writing of the electrode structures.
Solution Approach 2:
The patent substitutes the mechanical and chemical lithographic system with a laser-based ablation system. Instead of using mechanical masks, chemical etchants, and multiple processing steps, the laser directly writes the electrode patterns through controlled ablation, simplifying the overall manufacturing process while maintaining precision.
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 allows for precise and efficient formation of electrode patterns in the transparent conductive layer on glass substrates with minimal risk of thermal damage to underlying layers, improving the yield and efficiency over traditional lithographic methods.
Implementation Method 1
forming grooves using a laser
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A method of forming an electrode structure for a capacitive touch sensor in a first transparent conductive layer (19) which is located on a first side of a glass substrate (5) on the second side of which is a colour filter layer (11,12,13) over-coated with a transparent non- conductive layer(15) and a second transparent conductive layer (7), by a direct write laser scribing process using a pulsed solid state laser (22), the laser wavelength in the range 257nm to 266nm and a pulse length in the range 50fs to 50ns so grooves (21) are formed in the first transparent conductive layer (19) to electrically isolate areas of the first transparent conductive layer (19) on opposite sides of each groove (21). This selection of wavelength and pulse length enables the grooves (21) to be formed with substantially no damage to the underlying colour filter layer (11, 12, 13), the transparent non- conductive layer (15) or the second transparent conductive layer (7) on the second side of the glass substrate (5).