Display Panel Test Line Structure for Bezel-Free Pad Removal

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Solution Overview

Problem

The presence of test pads on display panels after manufacturing complicates the manufacturing process, restricts narrow bezel designs, and increases the risk of damage to main lines and panels during etching operations.

Innovation Solution

A manufacturing method for display devices that includes a structure with a first lower etching stopper layer between the substrate and test line, a back coating film, and a multi-etching stopper layer configuration to facilitate cutting and reduce damage, ensuring test pads are not present on the final substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If test pads are placed inside the display panel to perform testing during manufacturing, then the test process can be performed, but the manufacturing process becomes complicated and test pads remain on the substrate after manufacturing

Engineering Contradiction:

Improvetest process capabilityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent extracts the test pad from the final substrate by introducing a test pad substrate that is temporarily attached during manufacturing and then completely removed after testing. This allows the test pad to be present during the test process but absent from the final product, resolving the contradiction between needing test pads for manufacturing testing and avoiding their presence in the final device.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the test pad structure into a separate test pad substrate that is distinct from the main display substrate. This segmentation allows the test pad substrate to be independently managed - attached during manufacturing for testing, then completely removed after testing, thereby simplifying the overall manufacturing process while maintaining test capability.

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If test pads are disposed inside the display panel, then testing can be performed, but the bezel design is restricted and the display area is reduced

Engineering Contradiction:

Improvetest process capabilityVSAvoiddisplay area

Core Design Contradiction:

Ease of manufactureVSArea of stationary object

Solution Approach 1:

By extracting the test pad onto a separate test pad substrate that is temporarily attached and then removed, the patent eliminates the need for test pads to occupy space within the display panel's bezel area. This allows the display area to extend to the edges of the substrate without being constrained by permanent test pad structures.

Inventive Principle:

Principle #2Taking out (Extraction)

3Ease of manufacture

If etching operations are performed during manufacturing, then the test pad substrate can be removed, but the main lines and substrate may be damaged

Engineering Contradiction:

Improvetest pad removalVSAvoidline and panel integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent introduces an intermediary protective layer between the etching process and the main lines/substrate. This protective layer acts as a mediator that allows the etching operation to remove the test pad substrate while preventing the etching from directly contacting and damaging the main lines and substrate, thus resolving the contradiction between removing test pads and protecting sensitive components.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies beforehand cushioning by pre-forming a protective layer over the main lines and substrate before performing the etching operation. This protective layer serves as a cushion that absorbs the potential damage from the etching process, allowing safe removal of the test pad substrate without compromising the integrity of underlying components.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Productivity

If the manufacturing process includes multiple etching steps, then the test pad substrate can be removed, but the risk of damage to main lines increases

Engineering Contradiction:

Improvemanufacturing process completionVSAvoiddamage risk to main lines

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The protective layer serves as an intermediary that allows multiple etching steps to proceed for complete test pad substrate removal while preventing these etching operations from damaging the main lines. The protective layer mediates between the aggressive etching process and the sensitive main lines, enabling productivity without increasing damage risk.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20250386627A1Display device and manufacturing method thereof

Publication Date: 2025.12.18 LG DISPLAY CO LTD

AI summary

A display device may include a substrate including a display area and non-display area, a signal line disposed in the display area of the substrate, a test line disposed in the non-display area and connected to the signal line, and a first lower etching stopper layer disposed between the substrate and the test line. A rear surface edge of the substrate may be located further inside than an outer side edge of the first lower etching stopper layer. An end portion of the test line may include a portion that is located further outside than the rear surface edge of the substrate and does not overlap the substrate.