Flexible Display Panel Base Layer Segmentation for Bonding Reliability
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Solution Overview
Problem
The existing display devices face challenges in achieving reliable bonding between the display panel and the circuit board, particularly in flexible display devices where the bending of the panel can lead to disconnection and reduced adhesion of the conductive adhesive, affecting the electrical connection and overall reliability.
Innovation Solution
The display device incorporates a conductive adhesive member with a photoinitiator, a light transmission layer with high transmittance, and a layered base structure with openings and sub-layers to ensure effective electrical connection and adhesion, using a polyimide material and polymer-based light transmission layers to enhance bonding reliability and photocuring efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional bonding structure is used between display panel and circuit board, then the device can be manufactured with standard processes, but the bonding reliability deteriorates under bending conditions
Solution Approach 1:
The base layer is divided into multiple sub-layers (first sub base layer, second sub base layer, etc.) with barrier layers between them. This segmentation allows each sub-layer to perform specific functions such as adhesion, barrier protection, and flexibility, thereby improving bonding reliability under bending conditions while managing the overall structural complexity through functional division.
Solution Approach 2:
The patent employs composite material structures where the base layer combines multiple sub-layers with different properties (polyimide materials, barrier layers with distinct characteristics). This composite approach enables the bonding structure to simultaneously achieve flexibility for bending, adhesion for reliable bonding, and barrier protection, resolving the contradiction between reliability and structural simplicity.
2Reliability
If the conductive adhesive member is positioned close to the display pads for compact design, then the device size is reduced, but the photocuring efficiency deteriorates due to light blocking
Solution Approach 1:
The base layer structure is designed with local variations: openings are positioned specifically in non-pad areas to allow light transmission for photocuring, while pad areas maintain continuous layer structure for electrical connection. This local quality differentiation enables the bonding structure to achieve both compact area and high photocuring efficiency in their respective zones.
Solution Approach 2:
The light transmission layer acts as an intermediary element positioned between the light source and the conductive adhesive member. It selectively transmits light through openings in non-pad areas while blocking light in pad areas, thereby enabling efficient photocuring of the adhesive without compromising the electrical connection integrity, and allowing compact bonding area design.
3Strength
If a single-layer base structure is used to simplify manufacturing, then the manufacturing process is simplified, but the adhesion and bonding strength deteriorate
Solution Approach 1:
The base layer is segmented into multiple sub-layers (first sub base layer, second sub base layer, third sub base layer, etc.) where each sub-layer contributes to overall adhesion strength. This segmentation allows individual layers to be optimized for specific adhesion requirements while distributing the total adhesion load across multiple interfaces, thereby improving overall bonding strength without requiring excessive thickness in a single layer.
Solution Approach 2:
The layered base structure employs composite materials with different properties in each sub-layer and barrier layer. This composite construction provides enhanced adhesion strength through multiple bonding interfaces, while the varied material properties (flexibility, barrier characteristics, adhesion promoters) in different layers work synergistically to improve overall bonding performance beyond what a single homogeneous layer could achieve.
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 configuration improves the bonding reliability between the display panel and the circuit board, ensuring stable electrical connections even in flexible and bent configurations, and enhances the photocuring process for the adhesive, leading to a more reliable and efficient display device.
Implementation Method 1
a conductive adhesive member that electrically connects the circuit board to the display panel... a light transmission layer disposed in each of the plurality of openings and having a light transmittance greater than a light transmittance of the base layer
Implementation Method 2
a conductive adhesive member that electrically connects the circuit board to the display panel... improves the bonding reliability between the display panel and the circuit board
Data Source
AI summary
A display device includes a circuit board including a plurality of circuit pads, a display panel including a plurality of pad areas and a plurality of non-pad areas alternately arranged in a direction, and a conductive adhesive member that electrically connects the circuit board to the display panel. The display panel further includes a base layer including a plurality of openings, which overlap the plurality of non-pad areas in a plan view, respectively, a light transmission layer disposed in each of the plurality of openings and having a light transmittance greater than a light transmittance of the base layer, and a plurality of display pads which correspond to the plurality of circuit pads and are arranged in the direction to overlap the plurality of pad areas in a plan view, respectively.