IPS LCD Common Electrode Peeling Prevention
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Solution Overview
Problem
Miniaturized IPS-type liquid crystal display devices face challenges in manufacturing yield and reliability due to film peeling-off issues between interlayer insulation films and common electrodes, particularly at small pixel pitches, which complicates the TFT substrate structure and reduces tolerance in design and process.
Innovation Solution
The solution involves forming a first insulation film on the source electrode, an organic insulation film, and a second insulation film on the common electrode, with specific through hole and opening portion configurations to enhance adhesive strength and prevent peeling-off, using SiN films and low-temperature CVD for the second insulation film to alleviate stress and ensure proper alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel size is reduced to achieve high-definition display (VGA on three-inch screen), then the display resolution is improved, but the film peeling-off occurs between interlayer insulation films and common electrodes
Solution Approach 1:
The through hole is divided into two distinct parts: a large hole portion extending from the outer surface to a first depth, and a small hole portion extending from the first depth to a second depth. This segmentation allows different structural characteristics in different regions, preventing film peeling by distributing stress differently across the hole structure.
Solution Approach 2:
The inner wall of the through hole exhibits local quality variation: the large hole portion has a first inner wall, while the small hole portion has a second inner wall with different characteristics. This local differentiation optimizes adhesion properties at specific locations where peeling is most likely to occur.
2Illumination intensity
If the pixel electrode area ratio is increased to maintain transmissivity in miniaturized devices, then the optical transmissivity is improved, but the design and process tolerance is reduced
Solution Approach 1:
The solution moves from a two-dimensional planar structure to a three-dimensional hierarchical hole structure. By creating a through hole with multiple depth levels (first depth and second depth) and corresponding large and small hole portions, the design accommodates miniaturization while maintaining manufacturing tolerance through vertical dimension exploitation.
3Reliability
If multiple insulation films are stacked to prevent film peeling-off, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The small hole portion is nested within the large hole portion, creating a nested hierarchical structure. The first insulation film forms the large hole, and the second insulation film forms the small hole within it. This nesting approach prevents peeling while maintaining a compact structure that doesn't excessively increase device complexity.
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 configuration increases manufacturing yield and reliability by preventing film peeling-off, enhancing the adhesive strength of interlayer insulation films and maintaining high field-of-view and transmissivity characteristics in miniaturized high-pixel-definition liquid crystal display devices.
Implementation Method 1
forming a first insulation film on the source electrode, an organic insulation film, and a second insulation film on the common electrode
Data Source
AI summary
In an IPS-type liquid crystal display device, peeling-off between a common electrode formed in a matted manner in plane and an interlayer insulation film is prevented. The common electrode is formed on an organic passivation film in a matted manner in plane, the interlayer insulation film is formed on the common electrode, and a comb-teeth-shaped pixel electrode is formed on the interlayer insulation film. The pixel electrode is connected with a source electrode via a through hole formed in the organic passivation film and an inorganic passivation film.