Transparent Conductive Electrode Bonding with Adhesive Intermediate Layer

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Solution Overview

Problem

Conventional methods for connecting transparent conductive electrodes to external circuits, such as anisotropic conductive films and conductive adhesives, face reliability issues under high temperature and humidity conditions, leading to delamination and cracking, which compromises electrical connectivity in miniaturized electronic devices like mobile phones and projectors.

Innovation Solution

A conductive electrode with an adhesive intermediate layer, typically made of chromium or titanium, and a metal layer formed by precious metals like gold or platinum, is used to enhance bonding strength and reliability, ensuring stable electrical connection without affecting the conductive performance of the transparent conductive film.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional connection methods (ACF or conductive adhesive) are used to connect transparent conductive electrodes to external circuits, then the device structure is simple and easy to manufacture, but the connection reliability deteriorates under high temperature and humidity conditions, leading to delamination and cracking

Engineering Contradiction:
Improveease of manufactureVSAvoidconnection reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies composite materials by creating a multi-layer conductive electrode structure consisting of a transparent conductive film layer, an adhesive intermediate layer, and a metal layer. This composite structure combines the advantages of each material: the transparent conductive film provides electrical conductivity and transparency, the adhesive intermediate layer provides strong bonding to the substrate, and the metal layer provides excellent electrical connectivity and environmental stability, thereby resolving the contradiction between ease of manufacture and connection reliability

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent introduces an adhesive intermediate layer as a mediator between the transparent conductive film and the external circuit substrate. This intermediate layer specifically addresses the adhesion problem by providing strong chemical bonding to both the transparent conductive film and the substrate, preventing delamination and cracking under harsh environmental conditions while maintaining the simplicity of the manufacturing process

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If the transparent conductive film is directly connected to the external circuit, then the manufacturing process is simple, but the bonding strength is insufficient, causing delamination and interface cracking under temperature cycling and high temperature high humidity environments

Engineering Contradiction:
Improvedevice complexityVSAvoidbonding strength
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

The patent transforms the simple direct connection structure into a composite multi-layer structure. By adding the adhesive intermediate layer and metal layer, the bonding strength is significantly enhanced while the transparent conductive film's electrical and optical properties are preserved. The composite structure ensures strong adhesion under temperature cycling and high temperature high humidity environments

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent segments the connection structure into distinct functional layers: the transparent conductive film layer for electrical conductivity, the adhesive intermediate layer for bonding, and the metal layer for electrical connectivity. This segmentation allows each layer to optimize its specific function, with the adhesive intermediate layer specifically designed to provide strong bonding strength without affecting the overall device complexity

Inventive Principle:
Principle #1Segmentation

3Ease of operation

If ACF is used for electrical connection, then the connection process is simple, but environmental reliability deteriorates with poor adhesion and susceptibility to delamination and interface cracking

Engineering Contradiction:
Improveease of operationVSAvoidenvironmental reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent replaces the single-material ACF connection method with a composite multi-layer conductive electrode structure. The adhesive intermediate layer provides superior adhesion properties, the metal layer provides environmental stability and electrical connectivity, and the transparent conductive film maintains electrical conductivity. This composite approach significantly improves environmental reliability while maintaining ease of operation through a streamlined manufacturing process

Inventive Principle:
Principle #40Composite materials

4Reliability

If bonding methods are used to connect transparent conductive film to external circuits, then electrical connectivity is achieved, but connection reliability is limited and operation space is constrained

Engineering Contradiction:
Improveconnection reliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses composite materials to achieve both high connection reliability and maintained simplicity. The multi-layer structure of transparent conductive film, adhesive intermediate layer, and metal layer provides superior electrical connectivity and environmental reliability while the integrated design keeps the overall device complexity manageable through a unified manufacturing process

Inventive Principle:
Principle #40Composite materials

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 solution significantly improves the bonding strength between the conductive electrode and the external circuit, enhancing reliability and stability, and reduces the risk of delamination, thereby achieving effective and reliable electrical interconnection in harsh environments.

Implementation Method 1

an adhesive intermediate layer disposed on the transparent conductive film

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

a metal layer disposed on the adhesive intermediate layer and configured to be connected to an external circuit

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP4020502B1Electronic device comprising a conductive electrode
Publication Date: 2023.11.01 HONOR DEVICE CO LTD
  • EP4020502B1 patent drawingFigure 1~3
  • EP4020502B1 patent drawingFigure 4~5
  • EP4020502B1 patent drawingFigure 6~7

AI summary

This application relates to the field of conductive electrode and electronic device technologies, and in particular, to a conductive electrode, a preparation method thereof, and an electronic device. The conductive electrode includes: a transparent conductive film disposed on a substrate; an adhesive intermediate layer disposed on the transparent conductive film; and a metal layer disposed on the adhesive intermediate layer, where the metal layer is mainly formed by a precious metal and configured to be bonded to an external circuit. This application can improve bonding strength between the transparent conductive electrode and an external circuit and meet requirements for electrical connectivity and connection reliability.