Display Panel Pad Layout for Non-Destructive Bondability Testing

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Solution Overview

Problem

Existing display devices face challenges in effectively testing the bondability of ultrasonic bonding between a display panel and a flexible printed circuit film, with current methods being either destructive or time-consuming non-destructive testing.

Innovation Solution

The display panel incorporates a pad terminal design with a through-hole surrounded by the pad terminal and a lead terminal that overlaps this open portion, allowing for non-destructive testing of bondability by observing lead terminals inserted into the through-hole.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If transparent conductive oxide films are used as hole injection type electrodes, then visibility is improved, but manufacturing complexity increases due to multiple film deposition processes

Engineering Contradiction:

ImprovevisibilityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent extracts and removes the transparent conductive oxide film from the electrode structure, replacing it with a low-work-function metal film that provides both conductivity and hole injection functionality in a single layer, thereby simplifying the manufacturing process while maintaining visibility

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The low-work-function metal film serves multiple functions simultaneously: it acts as both the conductive electrode and the hole injection layer, eliminating the need for separate transparent conductive oxide films and simplifying the overall device structure

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of manufacture

If electron injection type electrodes are used, then manufacturing process is simplified, but image quality deteriorates due to electron leakage and dark spots

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidimage quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent inverts the electrode type from electron injection type to hole injection type by using low-work-function metal films, which prevents electron leakage and dark spots while maintaining manufacturing simplicity through single-layer deposition processes

Inventive Principle:

Principle #13The other way round (Inversion)

3Device complexity

If conventional electrode structures are used, then device structure is simple, but display uniformity deteriorates due to visible electrodes and non-uniform light emission

Engineering Contradiction:

Improvedevice structure simplicityVSAvoiddisplay uniformity

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by using low-work-function metal films with specific material properties (work function 4.0-5.0 eV) that are strategically positioned at the electrode interface to enable efficient hole injection and eliminate visible electrode effects, achieving uniform display characteristics

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite material structures combining low-work-function metal films with organic light-emitting materials, where the metal film's specific electrical and optical properties complement the organic materials to achieve both structural simplicity and display uniformity

Inventive Principle:

Principle #40Composite materials

4Reliability

If multiple thin films are deposited to form electrodes, then electrode functionality is enhanced, but production cost increases due to multiple vacuum deposition processes

Engineering Contradiction:

Improveelectrode functionalityVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent removes the expensive transparent conductive oxide film deposition process by replacing it with a single low-work-function metal film deposition, reducing the number of vacuum deposition steps from multiple to one, thereby lowering production costs while maintaining electrode functionality

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses low-work-function metal films that can be deposited in a single process step, replacing expensive multi-layer transparent conductive oxide structures, effectively using a simpler, more cost-effective material solution to achieve the required electrode performance

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 design enables efficient non-destructive testing of bondability, ensuring reliable ultrasonic bonding between the display panel and flexible printed circuit film.

Implementation Method 1

the low-work-function metal film has a work function of 4.0 eV to 5.0 eV and emits electrons, thereby forming an electron cloud

Methodology Applied

Scientific EffectThermionic emission: Thermionic Emission

Data Source

PatentEP3845962B1Display panel and display device comprising same

Publication Date: 2026.05.13 SAMSUNG DISPLAY CO LTD

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AI summary

A display panel is provided. A display panel according to one embodiment comprises: a display substrate which includes a display area and a pad area disposed around the display area, at least one pad terminal disposed on the substrate of the pad area, and an opened part which is at least partially and planarly surrounded by the pad terminal.