Display Panel Pad Layout With Protected Contact Bridge Rework
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Solution Overview
Problem
During the rework process of bonding a driving chip to a display panel, the organic insulating layer can be damaged, leading to the introduction of external impurities and corrosion of wiring, resulting in defects in the display device.
Innovation Solution
A display device design that includes an inorganic insulating layer with a pad and a contact bridge, where the distance from the pad to the contact bridge is greater than the distance to the electrostatic electrode, and an upper wiring that overlaps the contact bridge and electrostatic electrode, protected by organic insulating layers, to prevent damage from external impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the organic insulating layer is damaged during the rework process, then the pad can be cleaned and re-bonded, but external impurities are introduced and wiring corrosion occurs
Solution Approach 1:
The insulating structure is divided into multiple layers: a first organic insulating layer that can be damaged and removed during rework, and a second organic insulating layer that remains to provide continuous protection. This segmentation allows the pad area to be accessible for cleaning while maintaining protection over the contact bridge and wiring.
Solution Approach 2:
The protective function is extended from a single-layer two-dimensional structure to a multi-layer three-dimensional structure. The first organic insulating layer covers the pad for accessibility, while the second organic insulating layer covers the contact bridge and wiring from above, providing protection in a different spatial dimension.
2Area of stationary object
If the contact bridge is positioned closer to the pad for compact design, then device area is reduced, but the organic insulating layer becomes more vulnerable to damage
Solution Approach 1:
The protective coverage is segmented into two layers with different spatial extents. The first organic insulating layer extends to expose the pad for bonding access, while the second organic insulating layer provides additional coverage over the contact bridge area, ensuring protection even when the contact bridge is positioned close to the pad.
Solution Approach 2:
The second organic insulating layer is formed beforehand to cover the contact bridge and wiring, creating a protective cushion that prevents impurity introduction and corrosion before any damage occurs to the first organic insulating layer during rework processes.
3Reliability
If the organic insulating layer fully covers the pad for protection, then wiring corrosion is prevented, but the pad cannot be accessed for bonding and rework
Solution Approach 1:
The organic insulating coverage is segmented into two functional layers: the first organic insulating layer is selectively removed or not formed over the pad area to ensure accessibility for bonding and rework operations, while the second organic insulating layer remains to provide protection over the contact bridge and wiring.
Solution Approach 2:
The insulating structure has different local properties: over the pad area, the structure is open or has reduced insulation to allow access, while over the contact bridge and wiring areas, full insulation coverage is maintained to prevent corrosion. This local differentiation satisfies both accessibility and protection requirements.
Data Source
AI summary
A display device includes a substrate including a display area and a non-display area, a first wiring at the non-display area of the substrate, a second wiring on a layer that is different from the first wiring at the non-display area of the substrate, an inorganic insulating layer on the first wiring and the second wiring, a pad on the inorganic insulating layer, and connected to a first end of the first wiring, a contact bridge on the inorganic insulating layer, and connecting the second wiring to a second end of the first wiring, an electrostatic electrode on the inorganic insulating layer between the pad and the contact bridge, a first organic insulating layer covering the contact bridge and the electrostatic electrode, and exposing the pad, a first upper wiring on the first organic insulating layer, and overlapping the contact bridge and the electrostatic electrode, and a second organic insulating layer on the first upper wiring.