Display Pad Elastic Protrusions for Reliable Chip Bonding
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Solution Overview
Problem
During the bonding process of a driving chip to a substrate in display devices, defects such as shorts or opens frequently occur due to the concentration of conductive balls on electrode sides or improper placement between electrodes.
Innovation Solution
Incorporating a substrate with elastic protrusions, specifically a combination of first and second elastic protrusions disposed on and between pad electrodes, respectively, which are electrically connected to bump electrodes, ensuring proper alignment and pressure distribution to reduce defect frequency and severity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If driving chip is bonded to substrate using conventional methods, then bonding process is simple, but defects such as shorts or opens frequently occur
Solution Approach 1:
Elastic protrusions are pre-formed on the substrate before bonding the driving chip. These protrusions are positioned at specific locations corresponding to pad electrodes and intermediate positions, preparing the substrate in advance to ensure proper contact and pressure distribution during bonding, thereby preventing shorts and opens without complicating the bonding process itself
Solution Approach 2:
The elastic protrusions serve as cushioning elements that compensate for misalignment or unevenness during bonding. By having these elastic structures in place beforehand, the system can absorb positioning errors and maintain reliable electrical connections, reducing defect occurrence without requiring extremely precise bonding alignment
2Reliability
If elastic protrusions are added to substrate, then defect occurrence is reduced, but substrate structure becomes more complex
Solution Approach 1:
The elastic protrusions are divided into two distinct types: first elastic protrusions positioned on pad electrodes and second elastic protrusions positioned between pad electrodes. This segmentation allows each type to perform its specific function optimally while maintaining a systematic and manageable structure that doesn't overly complicate the substrate design
Solution Approach 2:
The elastic protrusions serve multiple functions simultaneously: they provide mechanical pressure for bonding, ensure proper alignment between driving chip and substrate, compensate for positioning variations, and maintain electrical contact reliability. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in overall device complexity
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
The use of elastic protrusions on the substrate reduces the occurrence and severity of defects during chip bonding by ensuring consistent pressure and alignment, enhancing the reliability of the display device.
Implementation Method 1
A plurality of elastic protrusions includes a plurality of first elastic protrusions disposed on each of the pad electrodes and a plurality of second elastic protrusions disposed between the pad electrodes
Data Source
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AI summary
A display device includes a substrate including a display area and a pad area. A plurality of pad electrodes is disposed in the pad area on the substrate. A plurality of elastic protrusions including a plurality of first elastic protrusions is disposed on each of the pad electrodes and a plurality of second elastic protrusions is disposed between the pad electrodes on substrate, in a plan view. A conductive layer is disposed on each of the first elastic protrusions. A driving chip overlaps the pad area and includes a base portion facing the substrate and a plurality of bump electrodes attached to one surface of the base portion and overlapping the pad electrodes, respectively.