TFT Backplane Metal Light Shielding Layer for Micro-LED Displays
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Solution Overview
Problem
Current micro-LED display backplanes, made with top gate LTPS TFTs, face challenges in manufacturing large-size displays due to limited glass size and the need for multiple panel assembly, which results in visual defects from black lines and increased manufacturing steps.
Innovation Solution
A thin film transistor (TFT) backplane design featuring a substrate with a metal light shielding layer and a metal line layer positioned under the shielding layer to connect to external driving chips, reducing the side frame size and simplifying manufacturing steps by eliminating the need for a conventional shield metal layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple display panels are assembled to create large-size displays, then the display size requirement is met, but black lines appear between panels and visual effect is degraded
Solution Approach 1:
The patent moves the metal line layer from the front surface to the back surface of the substrate, utilizing the third dimension (depth) to relocate electrical connections. This allows the front surface edge area to be minimized while maintaining electrical functionality, thereby eliminating black lines between assembled panels and improving visual effect.
2Area of stationary object
If the side frame size is reduced to improve visual quality, then the display area increases, but the manufacturing complexity of the TFT backplane increases
Solution Approach 1:
By relocating the metal line layer to the back surface of the substrate, the patent enables reduced side frame dimensions while maintaining all necessary electrical connections. The via holes provide vertical connectivity between the back surface metal lines and the front surface active layers, simplifying the overall manufacturing process despite the compact design.
3Ease of manufacture
If the metal line layer is positioned at the front surface for electrical connections, then the connection is straightforward, but the side frame size increases and manufacturing steps increase
Solution Approach 1:
The patent positions the metal line layer on the back surface of the substrate rather than the front surface. This spatial reconfiguration allows the side frame size to be minimized while electrical connections are achieved through via holes that penetrate the substrate, providing direct vertical pathways for signal transmission.
4Object-affected harmful factors
If a conventional shield metal layer is added to block light from the active layer, then light shielding is improved, but the manufacturing steps and costs increase
Solution Approach 1:
The patent combines the light shielding function with the existing metal line layer by positioning it on the back surface of the substrate. This single layer simultaneously blocks light from reaching the active layer and provides electrical connections through via holes, eliminating the need for a separate shield metal layer and reducing manufacturing complexity.
Solution Approach 2:
The metal line layer on the back surface serves dual functions: it acts as a light shielding layer to prevent light interference with the active layer, and it provides electrical connections to the TFT components. This multi-functionality reduces the total number of manufacturing steps and lowers production costs.
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 the production of large-size micro-LED displays with reduced side frame size and manufacturing costs, improving visual quality and efficiency by positioning the metal line layer under the shielding layer and using the metal light shielding layer as a conventional shield, thus simplifying the manufacturing process.
Implementation Method 1
at least one metal light shielding layer, positioned on a lower surface of the substrate corresponding to the active layer, configured to perform a light shielding for the active layer
Data Source
AI summary
A TFT backplane and a micro-LED display are provided A metal light shielding layer is placed at the lower surface of the substrate and the position of the metal light shield layer is corresponding to the active layer. This reduces the size of the side frame, which is used when assembling multiple displays in a large-size micro LED display application. This could meet the demand of large-size micro-LED display. In addition, this could further reduce the steps of depositing and patterning a conventional shield metal layer in a convention process of manufacturing the TFT. Therefore, the manufacturing steps of the TFT backplane are simplified and thus the manufacturing cost is reduced.