Anisotropic Conductive Film Using Meltable Balls Against Moisture Shorts

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Solution Overview

Problem

Existing display devices face challenges in maintaining low resistance characteristics and preventing short circuits due to moisture permeation, which affects the reliability of the devices, particularly in the bonding force between electrodes.

Innovation Solution

The use of an anisotropic conductive film with different types of conductive particles, including conductive balls with polymer cores and metal layers, and meltable materials, ensures a large contact area and bonding force to electrodes, while maintaining contact even in the event of resin expansion due to moisture permeation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conductive particles are used to electrically connect the display panel and the flexible film, then electrical connection is achieved, but resin expansion due to moisture permeation causes short circuits

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidshort circuit risk from resin expansion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The conductive particles are segmented into two distinct types with different functions: first conductive particles (metal core with polymer layer) for electrical connection and second conductive particles (meltable material) for maintaining contact during resin expansion. This segmentation allows each type to address specific aspects of the reliability problem independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent utilizes parameter changes in the second conductive particles by selecting materials with different thermal expansion coefficients and melting points. These particles melt at specific temperatures to accommodate resin expansion while maintaining electrical contact, dynamically adapting to dimensional changes in the bonding resin.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If conductive particles are used to ensure electrical connection, then conductivity is achieved, but contact area with electrodes is insufficient

Engineering Contradiction:

Improveelectrical connection stabilityVSAvoidcontact area with electrode

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The first conductive particles have a localized structure with a metal core surrounded by a polymer material layer. This local quality differentiation allows the metal core to provide electrical conductivity while the polymer layer increases the contact area with the electrode, addressing both conductivity and contact area requirements simultaneously.

Inventive Principle:

Principle #3Local quality

3Reliability

If bonding force is increased to secure low resistance characteristics, then electrical connection is improved, but adaptability to resin expansion is reduced

Engineering Contradiction:

Improvebonding forceVSAvoidadaptability to dimensional changes

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The second conductive particles made of meltable material provide dynamic adaptability to dimensional changes in the bonding resin. When the resin expands due to moisture permeation, these particles can deform or melt to maintain contact, allowing the bonding structure to dynamically adapt to changing conditions while maintaining electrical connection.

Inventive Principle:

Principle #15Dynamics

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 enhances the reliability of display devices by securing low resistance characteristics and preventing short circuits, thereby improving the overall performance and durability.

Implementation Method 1

a plurality of second conductive balls dispersed in the base resin, each of the plurality of second conductive balls being made of a meltable material

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS12615931B2Anisotropic conductive film and display device including same

Publication Date: 2026.04.28 SAMSUNG DISPLAY CO LTD

AI summary

The disclosure relates to a display device and an anisotropic conductive film. An anisotropic conductive film disposed between a display panel and a printed circuit board, the anisotropic conductive film including a base resin, a plurality of first conductive balls dispersed in the base resin, each of the plurality of first conductive balls including a core made of a polymer material and at least one metal layer surrounding the core, and a plurality of second conductive balls dispersed in the base resin, each of the plurality of second conductive balls being made of a meltable material, and the anisotropic conductive film having a first area in which the anisotropic conductive film overlaps the first pad electrode and the first lead electrode in a thickness direction of the display device, and a second area as an area disposed between the first lead electrode and the second lead electrode. Each of the metal layer of the first conductive ball and a surface of the second conductive ball are in contact with both the first pad electrode and the first lead electrode.