Corrosion-Resistant Bridge Layers for Mother TFT Array Substrates

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Solution Overview

Problem

During the cutting of mother TFT array substrates, the printed wirings are broken, exposing metal layers to moisture, which leads to corrosion and potential damage to the TFTs, as the protective layers are not effective in preventing moisture ingress and subsequent erosion.

Innovation Solution

Incorporating bridge layers made of corrosion-resistant materials, such as ITO or IZO, between the metal layers in the printed wirings, which connect the metal layers without filling the gaps, thereby containing corrosion and maintaining the integrity of the TFTs, and these bridge layers are formed during the same photolithographic mask process as the pixel electrodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the mother TFT array substrate is cut into individual TFT array substrates, then individual substrates can be obtained for assembly, but the printed wirings are broken and metal layers are exposed to moisture causing corrosion

Engineering Contradiction:

Improveease of manufactureVSAvoidintegrity of TFTs

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

A bridge layer of corrosion-resistant material is formed over the metal layer before the substrate is cut. This preliminary protective action ensures that when the substrate is later divided into individual TFT array substrates, the bridge layer remains intact and continues to protect the metal layer from moisture ingress at the cut edges, preventing corrosion while allowing easy manufacture of individual substrates

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The bridge layer acts as an intermediary protective element between the metal layer and the corrosive environment. It is a corrosion-resistant material that differs from both the metal layer and the surrounding environment, serving as a mediator that prevents direct contact between moisture and the metal layer, thereby preventing corrosion while maintaining structural integrity

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a protective layer is applied over the metal layer, then the metal layer is isolated from the environment, but the protective layer does not prevent moisture ingress through cuts

Engineering Contradiction:

Improveprotection of metal layerVSAvoidmoisture erosion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The structure employs a composite material system consisting of the metal layer for electrical conductivity and the bridge layer of corrosion-resistant material for protection. This composite structure combines the advantageous properties of different materials: the metal layer provides the necessary electrical function while the bridge layer provides superior corrosion resistance, together creating a structure that resists moisture erosion effectively

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS8178878B2Mother thin film transistor array substrate and thin film transistor array substrate fabricated therefrom

Publication Date: 2012.05.15 RED OAK INNOVATIONS LTD

AI summary

A mother thin film transistor (TFT) array substrate includes an insulating substrate, at least two TFT arrays and printed wirings. The TFT array includes TFTs formed on the insulating substrate. The printed wirings are connected to the TFT arrays. The printed wiring includes a discontinuous metal layer and at least one bridge layer connecting the discontinuous metal layer. The bridge layer is made from corrosion-resistant material.