Coating Insulation Film for IPS LCD Short Circuit Prevention
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Solution Overview
Problem
In IPS liquid crystal display panels, the thin insulation film between the sheet-like opposing electrode and the partially-linear pixel electrode can become too thin in through hole portions with large height differences, leading to a risk of short circuits.
Innovation Solution
A coating insulation film with a thickness of 100 nm to 500 nm is formed between the electrodes, and a second contact hole is created within the first contact hole to ensure electrical connection while maintaining a flat surface, preventing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulation film thickness is reduced to 100 nm to 500 nm to maintain panel flatness and prevent domain generation, then the panel flatness and image display quality are improved, but the insulation film becomes too thin in through hole portions with large height differences, causing a risk of short circuits
Solution Approach 1:
The insulation film is segmented into two distinct parts: a base insulation film with greater thickness (including through hole portions) and a coating insulation film with thinner thickness (100 nm to 500 nm) formed only in non-through hole areas. This segmentation allows each part to fulfill its specific function - the base film prevents short circuits while the coating film maintains panel flatness
Solution Approach 2:
Different thickness specifications are applied to different locations on the insulation film. The base insulation film has sufficient thickness (500 nm or more) in through hole portions to prevent short circuits, while the coating insulation film has reduced thickness (100 nm to 500 nm) in non-through hole areas to maintain panel flatness and prevent domain generation
2Shape
If the insulation film is made thin to achieve a flat panel surface, then the panel flatness is improved, but the through hole portions with height differences of 1 μm or larger cannot maintain adequate insulation thickness
Solution Approach 1:
The insulation structure is divided into a base insulation film that provides thickness in through hole areas and a coating insulation film that provides flatness in non-through hole areas, allowing both requirements to be satisfied simultaneously
Solution Approach 2:
The solution transitions from a single-dimensional thickness control to a two-dimensional approach where the base insulation film covers the entire surface including through holes, and the coating insulation film is selectively formed only in non-through hole areas, creating a stepped structure that satisfies both flatness and insulation requirements
Data Source
AI summary
A liquid crystal display device that includes a first substrate, a second substrate, and a liquid crystal material sandwiched between the first and second substrates. In the device, the first substrate includes an active element, a first insulation film formed above the active element, a first electrode formed above the first insulation film, a second insulation film formed above the first electrode, and a second electrode formed above the second insulation film. The second insulation film is a coating insulation film, the first insulation film has a first contact hole, the second insulation film is formed between the first and second electrodes, and inside of the first contact hole, the second insulation film formed inside of the first contact hole is formed with a second contact hole, the second electrode is a pixel electrode, the second electrode is electrically connected to the active element via the second contact hole, and a retention capacity is formed by the first and second electrodes and the second insulation film. The resulting liquid crystal display device of such a configuration causes no short circuit in a height-different portion between electrodes formed on both sides of an insulation film.