Multi-Layer Connection Pad Ultrasonic Bonding for Display Devices
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Solution Overview
Problem
Existing display devices face challenges in improving adhesion between the display panel and a flexible film attached to the side surface, which affects the reliability and efficiency of signal transmission, leading to increased non-display areas and potential image quality issues.
Innovation Solution
The implementation of a display device design featuring a display panel with panel pads, connection pads, and a circuit board where the third connection pad has a lower melting point and is ultrasonically bonded to lead signal lines, ensuring strong and reliable bonding while minimizing the non-display area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a flexible film is attached to the side surface of the display panel to transmit driving signals, then the non-display area is reduced, but the adhesion between the display panel and flexible film is insufficient
Solution Approach 1:
The connection pad is divided into multiple layers (first connection pad, second connection pad, third connection pad) with different functions. The first connection pad contacts the panel pad, the second connection pad is disposed on top, and the third connection pad is directly bonded to the lead signal line. This segmentation allows each layer to optimize for its specific function, improving overall adhesion while maintaining compact design.
Solution Approach 2:
The connection pad uses a composite structure with multiple materials having different melting points. The third connection pad has a lower melting point than the first and second connection pads, enabling selective bonding during ultrasonic bonding process. This composite material approach ensures strong adhesion between the flexible film and display panel while preventing damage to other components.
2Reliability
If ultrasonic bonding is used to bond leads to pads, then bonding reliability is improved, but the melting point of bonding materials must be controlled to prevent damage
Solution Approach 1:
The invention changes the melting point parameter of the connection pad materials. The third connection pad is designed with a lower melting point than the first and second connection pads. During ultrasonic bonding, this parameter difference allows the third connection pad to bond to the lead signal line while the first and second connection pads remain intact, ensuring reliable bonding without damage.
Solution Approach 2:
Different parts of the connection pad structure have different material properties. The third connection pad has a lower melting point specifically at the bonding interface with the lead signal line, while the first and second connection pads maintain higher melting points for structural stability. This local quality differentiation enables precise control of the bonding process.
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 solution enhances the adhesion and bonding reliability between the display panel and the circuit board, reducing the non-display area and improving image quality by ensuring effective signal transmission and minimizing voids and shorts.
Implementation Method 1
The third connection pad may be ultrasonically bonded to the corresponding one of the lead signal lines
Data Source
AI summary
A display device includes a display panel including panel pads adjacent to the side surface of a display panel; connection pads disposed on the side surface of the display panel and connected to the panel pads; and a circuit board disposed on the side surface of the display panel and including lead signal lines directly bonded to the connection pads, wherein the connection pads include a first connection pad, a second connection pad disposed on the first connection pad, and a third connection pad disposed on the second connection pad, and the first connection pad is in contact with corresponding one of the panel pads, and the third connection pad is directly bonded to corresponding one of the lead signal lines.