Display Pad Electrode Opening Layout for Reliable Connector Bonding
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Solution Overview
Problem
Display devices, particularly those with pad parts, face reliability issues due to inadequate design and manufacturing methods, leading to connectivity problems between the pad electrode and external devices.
Innovation Solution
A display device design featuring a substrate with a display area and pad area, including a circuit element layer, alignment electrodes, and a passivation layer, where the pad upper electrode has a smaller opening than the passivation layer opening, allowing for mechanical peeling to enhance adhesive force control and improve connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pad upper electrode opening is made larger to improve connectivity, then the adhesive force between the pad upper electrode and passivation layer decreases, but connectivity between pad electrode and external devices improves
Solution Approach 1:
The pad electrode structure is segmented into multiple layers: pad electrode, passivation layer with opening, and pad upper electrode with a smaller opening. This segmentation allows the passivation layer to provide adhesive support while the pad upper electrode maintains connectivity, resolving the contradiction between adhesive force and connectivity.
Solution Approach 2:
The opening in the pad upper electrode is designed to be smaller than the opening in the passivation layer, creating different local qualities. The larger passivation layer opening provides adequate adhesive area, while the smaller pad upper electrode opening ensures strong adhesion and prevents delamination, thus improving reliability without compromising connectivity.
2Reliability
If the pad upper electrode opening is made smaller to increase adhesive force, then reliability improves, but connectivity between pad electrode and external devices may be compromised
Solution Approach 1:
The segmented structure separates the adhesive function (passivation layer with larger opening) from the connection function (pad upper electrode with smaller opening). This allows each layer to optimize for its specific function, ensuring both reliability and connectivity are maintained.
Solution Approach 2:
The passivation layer acts as an intermediary between the pad electrode and the pad upper electrode. Its larger opening provides mechanical support and adhesive area, while the pad upper electrode's smaller opening ensures strong bonding. This intermediary structure resolves the contradiction by distributing functions across layers.
3Ease of manufacture
If the opening sizes are made equal for simplicity, then manufacturing process is easier, but adhesive force is insufficient leading to delamination
Solution Approach 1:
The design specifies that the pad upper electrode opening be smaller than the passivation layer opening, creating intentional local quality differences. This resolves the contradiction by optimizing each opening for its specific function: the passivation layer opening provides adhesive area, while the pad upper electrode opening ensures strong bonding.
Solution Approach 2:
By segmenting the opening design into two different sizes across different layers, the patent prevents delamination while maintaining manufacturability. The segmented approach allows each layer to be optimized independently, ensuring both reliability and ease of manufacture.
Data Source
AI summary
A display device includes a substrate including a display area and a pad area, a circuit element layer on the substrate, and an alignment electrode layer on the circuit element layer, wherein the circuit element layer includes a thin film transistor in the display area, and a pad electrode in the pad area, the alignment electrode layer includes a first alignment electrode and a second alignment electrode spaced from each other in the display area, and a pad upper electrode includes a first opening exposing the pad electrode in the pad area, and a light emitting element is on a space between the first alignment electrode and the second alignment electrode that are spaced from each other.