Uneven Display Panel Pads for Reliable Ultrasonic Bonding
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Solution Overview
Problem
Existing display devices face challenges in process reliability during the bonding of pads and bumps due to insufficient pressure and friction in ultrasonic bonding processes, leading to suboptimal electrical connections.
Innovation Solution
The introduction of uneven pads with organic layers having uneven surfaces and multiple conductive layers, which increase pressure and friction coefficients, enhancing the ultrasonic bonding process reliability by facilitating better material diffusion between pads and bumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flat pads are used in ultrasonic bonding, then the bonding process is simple, but the pressure and friction are insufficient leading to poor electrical connections
Solution Approach 1:
The pad surface is transformed from a flat plane to an uneven surface with protrusions and recesses. This curvature modification increases the friction coefficient between the pad and bump during ultrasonic bonding, enhancing material diffusion and electrical connection reliability without requiring complex additional components
Solution Approach 2:
The pad structure incorporates localized uneven regions (protrusions and recesses) rather than uniformly changing the entire pad structure. This allows the bonding interface to have enhanced friction and pressure distribution exactly where needed, while maintaining simpler structures in non-critical areas, thus improving reliability without excessive complexity
2Reliability
If uneven pads with organic layers are introduced, then pressure and friction increase improving bonding, but manufacturing complexity increases
Solution Approach 1:
The pad structure combines multiple materials including conductive layers and organic layers in a composite configuration. The organic layer with uneven surface profile is integrated with conductive layers to simultaneously achieve enhanced friction for ultrasonic bonding and proper electrical conductivity, resolving the conflict between bonding reliability and manufacturing simplicity through material composition rather than mechanical complexity
3Reliability
If multiple conductive layers are added to the uneven pad, then electrical connection stability improves, but the number of manufacturing steps increases
Solution Approach 1:
Multiple conductive layers and the organic layer are merged into a single integrated pad structure formed through combined manufacturing processes. The uneven surface profile and multi-layer conductive structure are created in an integrated manner rather than as separate assembly steps, maintaining electrical connection stability while minimizing the increase in manufacturing complexity and preserving productivity
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 uneven pad structure improves the reliability of ultrasonic bonding by increasing pressure and friction, resulting in more stable electrical connections and improved process consistency.
Implementation Method 1
the upper surface of the uneven pad has an uneven shape, a friction coefficient of the uneven pad may increase. In such embodiments, a material of the uneven pad and a material of the bump corresponding to the uneven pad may easily diffuse to each other by a vibration applied in the ultrasonic bonding process
Implementation Method 2
a material of the uneven pad and a material of the bump corresponding to the uneven pad may easily diffuse to each other by a vibration applied in the ultrasonic bonding process
Implementation Method 3
since the uneven pad includes the organic layer having a predetermined thickness, the uneven pad may have a step difference. In such embodiments, a pressure transmitted to the uneven pad may increase in an ultrasonic bonding process
Data Source
AI summary
A display panel includes a substrate including a display area and a pad area spaced apart from the display area, and an uneven pad disposed on the substrate in the pad area. The uneven pad includes a first conductive layer, a first organic layer disposed on the first conductive layer and having an upper surface having an uneven shape, and a second conductive layer disposed on the first organic layer.