Micro LED Pad Insulation Layout to Prevent Bonding Short-Circuits
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Solution Overview
Problem
The clumping of conductive materials between pad electrodes of a flexible circuit board occurs when a display panel and the flexible circuit board are bonded, leading to short-circuits and burnt defects in display devices.
Innovation Solution
The display device incorporates a design with a specific thickness distribution of organic insulating layers to suppress the clumping of conductive materials, ensuring a larger total thickness of these layers where first pad electrodes are overlapped, thereby minimizing the risk of short-circuits and defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive materials are disposed between pad electrodes of a flexible circuit board, then electrical connection is achieved, but clumping occurs causing short-circuits and burnt defects
Solution Approach 1:
An organic insulating layer is introduced as an intermediary between the conductive materials (pattermed conductive material and flexible circuit board). This insulating layer prevents direct contact and clumping between the conductive materials while allowing electrical connection to function properly, thus eliminating short-circuit defects
Solution Approach 2:
The patent divides the insulating structure into multiple organic insulating layers (first organic insulating layer and second organic insulating layer) positioned at different locations. The first layer is between conductive materials in the active area, while the second layer is between pad electrodes in the non-active area, providing segmented protection against clumping throughout the device
2Ease of manufacture
If pad electrodes are disposed in the non-active area, then electrical connection to flexible circuit board is enabled, but clumping of conductive materials causes short-circuits
Solution Approach 1:
The organic insulating layer serves as a mediator between the pad electrodes and the flexible circuit board's conductive materials. It maintains the necessary electrical connection while preventing clumping and short-circuits, thus ensuring both ease of manufacture and reliability
Solution Approach 2:
The patent applies different insulating layer configurations to different areas: the first organic insulating layer is placed in the active area between conductive materials, while the second organic insulating layer is placed in the non-active area between pad electrodes. This local differentiation ensures appropriate protection for each functional zone
Data Source
AI summary
A display device, in one or more examples, may include a substrate, an active area, a non-active area, a pixel driving circuit disposed on the substrate in the active area, a plurality of micro LEDs which is disposed on the pixel driving circuit in the active area and is electrically connected to the pixel driving circuit, a plurality of organic insulating layers disposed on the substrate in each of the active area and the non-active area, and a plurality of first pad electrodes disposed on the plurality of organic insulating layers in the non-active area, wherein a total thickness of the plurality of organic insulating layers in an area overlapping the plurality of first pad electrodes is larger than a total thickness of the plurality of organic insulating layers in an area between the plurality of first pad electrodes.