Display Substrate ET Pad Layout for Reliable FPC Contact
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Solution Overview
Problem
During the lighting Electric Test (ET) for display substrates, there is no effective scheme to ensure a reliable electrical connection between the Flexible Printed Circuit (FPC) and the testing pad, leading to imperfect contact and failure in displaying images due to the insulation structure's thickness being greater than the testing pad's distance from the base substrate.
Innovation Solution
A display substrate design with an ET region featuring testing pads and an insulation structure where the distance between the insulation structure's surface and the base substrate is not greater than the testing pad's distance from the base substrate, allowing for full contact during the ET, comprising layers such as active, gate insulation, interlayer insulation, passivation, and planarization layers, with specific configurations like removing certain layers in the ET region to reduce thickness and ensure contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulation structure thickness is greater than the testing pad distance from base substrate, then insulation is improved, but full contact during ET cannot be achieved
Solution Approach 1:
The substrate is segmented into display region and testing region, with the insulation structure having different thickness characteristics in each region. In the testing region, the insulation structure thickness is controlled to be not greater than the testing pad distance from the base substrate, enabling full contact during ET, while in the display region, the insulation structure maintains appropriate thickness for insulation.
Solution Approach 2:
The insulation structure exhibits local quality variation: in the testing region, it has reduced thickness (not greater than the testing pad distance from base substrate) to enable precise contact, while in the display region, it maintains full thickness for insulation. This local differentiation simultaneously achieves both insulation and contact precision requirements.
2Reliability
If the insulation structure surrounds the testing pad completely, then insulation performance is improved, but the flexible circuit board cannot make full contact with the testing pad
Solution Approach 1:
The substrate is divided into display region and testing region. In the testing region, the insulation structure is configured with reduced thickness (not greater than the testing pad distance from base substrate), creating a contact-friendly zone that allows the flexible circuit board to make full contact with the testing pad, while the display region maintains complete insulation structures.
Solution Approach 2:
The insulation structure is designed with different characteristics in different regions: in the testing region, it has reduced thickness to facilitate easy contact operation, while in the display region, it maintains complete coverage for insulation performance. This local quality differentiation resolves the contradiction between insulation performance and contact capability.
Data Source
AI summary
A display substrate, a method for manufacturing the display substrate and a display device are provided. The display substrate includes an Electric Test (ET) region. At least one testing pad and an insulation structure surrounding the testing pad are arranged in the ET region, and a distance between a surface of the insulation structure distal to a base substrate of the display substrate and the base substrate is not greater than a distance between a surface of the testing pad distal to the base substrate and the base substrate.