Display Panel Pad Structure With Dummy Bump Lines Against Bonding Cracks
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Solution Overview
Problem
Cracks occur in the pad area of organic light-emitting display apparatuses during the bonding process due to increased step height caused by pressure on a substrate with low modulus of elasticity, leading to reduced reliability and potential defects.
Innovation Solution
A crack prevention structure is implemented by disposing dummy bump lines in the outer area of the pad part, mimicking high wiring density in the middle area to absorb pressure and prevent cracks during bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the thickness of the inorganic film in the bending part is reduced to improve the strain structure, then the flexibility and bendability of the panel are improved, but cracks occur in the pad area due to increased step height caused by pressure during the bonding process
Solution Approach 1:
The patent applies preliminary action by forming a dummy bump line structure in advance in the outer area of the pad part, before the actual bonding process occurs. This pre-formed structure creates a gradual height transition that prevents crack formation during subsequent bonding operations, addressing the reliability issue while maintaining the reduced film thickness for flexibility.
Solution Approach 2:
The dummy bump line acts as an intermediary structure between the pad area and the bending area. It mediates the stress distribution by providing a gradual height transition, preventing direct stress concentration that would cause cracks in the reduced-thickness inorganic film area, thus protecting the panel reliability while maintaining flexibility.
2Strength
If pressure is applied to the substrate during the bonding process of the driving chip, then the bonding strength is improved, but step height increases causing cracks in the pad area
Solution Approach 1:
The patent converts the harmful effect of pressure-induced step height into a beneficial gradual transition. By forming a dummy bump line structure that creates a controlled height gradient, the pressure applied during bonding is distributed more evenly, transforming what would be a crack-causing sharp step into a beneficial gradual transition that prevents cracking while maintaining bonding strength.
3Adaptability or versatility
If the pad area has low wiring disposition density in the outer area, then the design flexibility is improved, but the area cannot bear the pressure generated during the bonding process
Solution Approach 1:
The patent applies local quality by creating a dummy bump line structure specifically in the outer area of the pad part where wiring density is low. This localized structure provides the necessary pressure-bearing capacity in the specific region that lacks sufficient wiring support, while maintaining the overall low wiring density design for flexibility in other areas.
Data Source
AI summary
A display apparatus is disclosed that includes a crack prevention structure in an outer area of a pad unit that alleviates crack defects without lowering the reliability of the panel. The display apparatus includes a flexible printed circuit board and a data driver that are spaced apart from each other in a non-active area of a display panel, a first pad unit disposed under the flexible printed circuit board, a second pad unit disposed under the data driver, a dummy bump line that surrounds the outside of the input pad and one or more output pads of the second pad unit, and the branch lines of the dummy bump line may be disposed to pass among the COP wiring, the first scan line, the second and third scan lines, and the data line.