Anisotropic Conductive Film Structure for Reliable OLED Pad Contact

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Solution Overview

Problem

In the manufacturing of OLED displays on flexible substrates, the anisotropic conductive film's conductive balls often fail to contact the lines of the pad portion and chip-on film, leading to defective drives in the display device.

Innovation Solution

The anisotropic conductive film is designed with a pattern layer having a plurality of holes between non-conductive layers, where conductive balls are trapped and positioned to ensure smooth contact with the pad electrodes, preventing gathering and short circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the anisotropic conductive film uses conductive balls dispersed in the adhesive layer, then electrical connection is achieved, but the conductive balls may gather or fail to contact the pad electrodes reliably

Engineering Contradiction:
Improvecontact reliabilityVSAvoidpositioning accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by creating regions with different concentrations of conductive balls. The first concentration region has a higher density of conductive balls compared to the second concentration region. This localized variation ensures reliable contact in critical areas while maintaining overall functionality, directly addressing the issue of conductive balls failing to contact pad electrodes reliably.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements preliminary action by pre-positioning conductive balls in specific concentration regions before the bonding process. The patterned substrate guides the conductive balls to their intended locations, ensuring they are already in optimal positions to contact pad electrodes during bonding, thereby preventing gathering and ensuring reliable electrical connection.

Inventive Principle:
Principle #10Preliminary action

2Ease of manufacture

If the conductive balls are randomly distributed in the adhesive layer, then manufacturing is simplified, but contact with pad electrodes cannot be ensured

Engineering Contradiction:
Improvefilm fabricationVSAvoidelectrical connection
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The invention applies local quality by creating specific regions with different conductive ball concentrations within the adhesive layer. While the overall manufacturing process remains relatively simple, localized areas are optimized for reliable contact, thus maintaining ease of manufacture while improving electrical connection reliability.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patterned substrate acts as an intermediary that guides and positions the conductive balls during the bonding process. This intermediary structure enables controlled distribution of conductive balls without significantly complicating the manufacturing process, ensuring reliable pad electrode contact while maintaining ease of manufacture.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If the conductive balls are positioned to ensure contact, then defective drives are prevented, but the film structure becomes more complex

Engineering Contradiction:
Improvedevice operationVSAvoidfilm structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by introducing varying concentrations of conductive balls in specific regions rather than uniform distribution. This localized differentiation improves reliability by ensuring contact in critical areas while adding minimal complexity to the overall film structure, as the concentration variation is achieved through straightforward patterning techniques.

Inventive Principle:
Principle #3Local quality

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 ensures reliable contact between the conductive balls and the pad electrodes, preventing defective drives and improving the overall performance and reliability of the OLED display device.

Implementation Method 1

electrically connects the pad portion to the chip-on film by conductive balls of the anisotropic conductive film

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3330336B1Display device including an anisotropic conductive film
Publication Date: 2025.02.19 LG DISPLAY CO LTD
  • EP3330336B1 patent drawingFigure 1
  • EP3330336B1 patent drawingFigure 2~3
  • EP3330336B1 patent drawingFigure 4

AI summary

An anisotropic conductive film (ACF), and a display device including the same includes a first non-conductive layer (NCF1); a pattern layer (TPL) on the first non-conductive layer (NCF1) and having a plurality of holes (HP); a plurality of conductive balls (CB) in the plurality of holes (HP) of the pattern layer (TPL); and a second non-conductive layer (NCF2) on the pattern layer (TPL) and the plurality of conductive balls (CB).