Conductive Polymer Bonding Layer for Display Panel Electrical Connections
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Solution Overview
Problem
Existing display devices face challenges in achieving reliable electrical connections between high-resolution circuit lines and electronic elements, particularly in bonding display panels and circuit boards effectively.
Innovation Solution
A display apparatus is developed with a bonding layer comprising a conductive polymer, featuring conductive and non-conductive portions with distinct conductivity values. This bonding layer is patterned to include conductive portions overlapping panel and connection pads, and non-conductive portions not overlapping these pads, with a conductivity ratio of at least 100:1.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional conductive bonding member (ACF) is used to electrically connect the display panel and circuit board, then electrical connection is achieved, but reliability is insufficient for high-resolution circuit lines
Solution Approach 1:
The bonding layer is designed with spatially varying conductivity: conductive portions (with conductivity ≥10⁻⁶ S/cm) are positioned to overlap with circuit lines for electrical connection, while non-conductive portions (with conductivity <10⁻⁸ S/cm) are positioned in non-circuit regions. This local differentiation of material properties enables both reliable electrical connection and precise circuit line definition without interference.
Solution Approach 2:
The bonding layer is segmented into multiple functional regions: conductive portions for electrical connection, non-conductive portions for isolation, and intermediate portions with transitional conductivity. This segmentation allows each region to perform its specific function optimally, resolving the contradiction between connection reliability and manufacturing precision.
2Reliability
If the bonding layer has high conductivity to ensure electrical connection, then electrical connection is achieved, but short circuits may occur in non-circuit regions
Solution Approach 1:
The bonding layer's conductivity is locally optimized: high conductivity (≥10⁻⁶ S/cm) in regions overlapping circuit lines ensures reliable electrical connection, while low conductivity (<10⁻⁸ S/cm) in non-circuit regions prevents short circuits. This spatial differentiation eliminates the harmful effect of short circuits while maintaining connection reliability.
Solution Approach 2:
Intermediate portions with transitional conductivity (10⁻⁸ to 10⁻⁶ S/cm) act as buffer zones between conductive and non-conductive regions, providing gradual transition and further preventing harmful electrical interference while maintaining bonding functionality.
3Object-generated harmful factors
If the bonding layer has low conductivity to prevent short circuits, then short circuit risk is reduced, but electrical connection reliability deteriorates
Solution Approach 1:
The bonding layer exhibits local quality differentiation where conductivity is high (≥10⁻⁶ S/cm) in circuit regions for reliable connection and low (<10⁻⁸ S/cm) in non-circuit regions for short circuit prevention. This resolves the contradiction by ensuring each region has the appropriate conductivity for its function.
4Ease of manufacture
If a uniform bonding layer is used for both bonding and electrical connection, then manufacturing is simplified, but high-resolution circuit line bonding cannot be achieved
Solution Approach 1:
The bonding layer is fabricated with spatially varying properties using a photopolymerization process: a photocurable composition is applied uniformly, then selectively exposed to UV light through a mask pattern defining circuit line locations. This creates the required conductivity distribution while maintaining a relatively simple single-step fabrication process.
Solution Approach 2:
The mechanical/chemical process of selective photopolymerization replaces complex multi-step patterning processes. UV light exposure triggers polymerization only in exposed regions, automatically creating the desired conductivity pattern without mechanical intervention, thus simplifying manufacturing while achieving high precision.
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 a conductive polymer bonding layer with patterned conductive and non-conductive portions enhances the reliability of electrical connections in display devices, particularly in high-resolution applications, by ensuring effective bonding and minimizing issues like short circuits and open circuits.
Implementation Method 1
a bonding layer disposed between the display panel and the flexible circuit board and including a conductive polymer, wherein the bonding layer includes a plurality of conductive portions overlapping the plurality of panel pads and the plurality of connection pads and having a first conductivity value
Implementation Method 2
forming a bonding layer including a conductive portion and a non-conductive portion with irradiating the preliminary bonding layer with a first light
Data Source
AI summary
A display apparatus includes a display panel having a display region and a non-display region and including a plurality of panel pads disposed in the non-display region, a flexible circuit board including a plurality of connection pads overlapping the plurality of panel pads, and a bonding layer disposed between the display panel and the flexible circuit board and including a conductive polymer, wherein the bonding layer includes a plurality of conductive portions overlapping the plurality of panel pads and the plurality of connection pads and having a first conductivity value, and a plurality of non-conductive portions not overlapping the plurality of panel pads and the plurality of connection pads and having a second conductivity value smaller than the first conductivity value.