Flexible Backplane Metal Foil Interconnection
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Solution Overview
Problem
Existing methods for manufacturing flexible backplanes for direct drive display devices are costly and complex, particularly due to the use of polyimide substrates and limitations in high-density connecting terminal formation, leading to visible via holes and the need for additional inter-connectors.
Innovation Solution
A flexible backplane is manufactured using a plastic film substrate with a metal foil, where segment electrodes and connecting terminals are formed from the metal foil, and conductive via holes connect them to wires, eliminating the need for a polyimide layer and allowing for high-density Goldfinger type connecting terminals and direct ACF bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyimide substrate and complex manufacturing method are used, then interconnection between backplane and electronic components is simplified, but manufacturing cost increases
Solution Approach 1:
The patent removes the polyimide substrate layer from the conventional structure, extracting only the essential plastic film substrate with metal foil layers. This elimination of unnecessary layers simplifies the manufacturing process while maintaining the interconnection functionality through the redesigned metal foil structure with integrated connecting terminals.
Solution Approach 2:
The patent combines the segment electrodes and connecting terminals into a single metal foil layer, eliminating the need for separate interconnection components. This merging of functions into one integrated layer simplifies both manufacturing and the final structure while reducing material costs.
2Ease of manufacture
If conductive paste printing is used on PET substrate, then manufacturing process is simplified, but high density connecting terminal formation is not achievable
Solution Approach 1:
The patent changes the material parameter from conductive paste to metal foil, which enables high-density terminal formation through photolithography etching. This parameter change allows achieving both manufacturing simplicity and high precision in connecting terminal formation, resolving the contradiction between ease of manufacture and manufacturing precision.
3Reliability
If via holes are formed through PET substrate, then electrical connection is achieved, but via holes become visible from viewing side
Solution Approach 1:
The patent inverts the conventional via hole approach by forming blind via holes that stop at the metal foil layer rather than penetrating through to the viewing side. This inversion maintains electrical connection reliability while preventing via hole visibility, as the metal foil acts as a barrier that blocks the via holes from being seen through the display device.
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 approach reduces manufacturing costs, simplifies interconnection with electronic components, and eliminates visible via holes, enabling the production of backplanes with high-density connecting terminals and improved image quality.
Implementation Method 1
Segment electrodes are formed from one of the copper foils by, for example, photolithography
Implementation Method 2
Conductive paste is printed on one side of the PET substrate to form segment electrodes
Implementation Method 3
A chip-on-film (COF) may be bonded directly on the connecting terminals, utilizing anisotropic conductive film (ACF) bonding
Data Source
AI summary
The present invention is directed to a flexible backplane for direct drive display devices and methods for its manufacture. The flexible backplane has many advantages. Because there is no need for a polyimide layer and only one layer of metal foil is used, the backplanes may be manufactured at a relatively low cost.