Tiled Display Pad Layout to Prevent Test-Induced Delamination
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Solution Overview
Problem
Display devices experience delamination of driving pads due to test pads, which is a common issue in the manufacturing and testing process.
Innovation Solution
The display device incorporates a design with first and second pads on the front and back surfaces of the substrate, connected by side wirings, and uses an anisotropic conductive film to attach the printed circuit film, reducing the likelihood of pad delamination during testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If test pads are added to the pad area for testing purposes, then measurement precision is improved, but the driving pads become vulnerable to delamination due to mechanical stress during testing
Solution Approach 1:
The pad area is segmented into distinct first pads (driving pads) and second pads (test pads), with the second pads divided into multiple patterns. This segmentation isolates the testing function to specific areas, preventing test-related mechanical stress from affecting the driving pads.
Solution Approach 2:
Different regions of the pad area are assigned different functions: the first pads maintain driving functionality with stable bonding, while the second pads (with multiple patterns) are dedicated to testing. This local differentiation allows testing without compromising driving pad reliability.
2Measurement precision
If multiple patterns are used in the second pad area for testing, then testing capability is improved, but device complexity increases
Solution Approach 1:
The testing function is segmented into multiple discrete patterns within the second pad area. These patterns provide comprehensive testing capability while maintaining a systematic and organized structure that manages complexity through functional division.
Solution Approach 2:
The second pads with multiple patterns serve multiple testing functions simultaneously, allowing various test operations to be performed through a single integrated test pad structure, thereby managing complexity through multi-functionality.
3Reliability
If the printed circuit film is attached to the pad area, then electrical connection is established, but the bonding area is reduced making the pads more susceptible to delamination
Solution Approach 1:
The pad area is segmented into first pads and second pads, with the printed circuit film selectively attached to certain regions. This segmentation preserves bonding area in critical driving pad regions while establishing necessary electrical connections through the anisotropic conductive film in appropriate areas.
Solution Approach 2:
An anisotropic conductive film is introduced as an intermediary between the printed circuit film and the pad area. This intermediary provides electrical connection while maintaining the integrity and bonding area of the underlying pads, preventing direct attachment that would reduce bonding area.
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 design significantly reduces the probability of pad delamination by distributing the impact across multiple patterns, ensuring stable electrical connections and enhancing the durability of the display device.
Implementation Method 1
The printed circuit film may be attached onto the second pad area through an anisotropic conductive film
Data Source
AI summary
A display device includes a substrate including a display area including pixels, a pad area comprising pads and located adjacent to the display area and a side wiring area located adjacent to the pad area; and a printed circuit film attached to the pad area located on a back surface of the first substrate. The plurality of pads include first pads that electrically connect the printed circuit film to the pixels and at least one second pad disposed between adjacent ones of the first pads. The display device further includes at least one connection portion that electrically connects a first pad of the first pads and the at least one second pad to each other. Each of the first pads includes a first-first pad located on a front surface of the first substrate and a first-second pad located on the back surface of the first substrate.