Micro LED Display Pad Layout for Low-Pressure FPC Bonding
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Solution Overview
Problem
Existing display apparatuses face issues with pressure applied to connection lines when bonding a flexible circuit board, leading to potential lifting and defects due to moisture or oxygen permeation, which affects reliability and power consumption.
Innovation Solution
The display apparatus includes a substrate with specific non-active areas and insulating layers to minimize pressure on connection lines, ensuring a pressure margin and reducing lifting, thereby improving electrical connection and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulating layers are disposed over the entire pixel driving circuit area, then electrical insulation is improved, but pressure on connection lines during bonding increases causing lifting and reliability issues
Solution Approach 1:
The insulating layers are selectively disposed only in the active area and first non-active area, but not in the second non-active area where connection lines are located. This local differentiation allows electrical insulation where needed while avoiding pressure-induced lifting on connection lines during bonding operations.
2Reliability
If bonding pressure is increased to ensure good electrical connection between pad electrodes and flexible circuit board, then connection reliability is improved, but connection lines may lift and become susceptible to moisture and oxygen permeation
Solution Approach 1:
The insulating layers are positioned to extend into the second non-active area before bonding occurs, creating a protective cushion that prevents moisture and oxygen from permeating to the connection lines. This beforehand protection compensates for the potential harmful effects of bonding pressure that might cause lifting.
3Ease of manufacture
If the structure is simplified to reduce manufacturing complexity, then ease of manufacture is improved, but pressure management during bonding becomes more difficult affecting reliability
Solution Approach 1:
The substrate area is segmented into distinct regions (active area, first non-active area, second non-active area) with insulating layers selectively placed in specific segments. This segmentation simplifies the manufacturing process by providing clear zones for different functions while maintaining adequate pressure margin during bonding operations.
Data Source
AI summary
A display apparatus in some examples can include a substrate having an active area and a non-active area, a first non-active area enclosing the active area, a bending area extending from the first non-active area, a second non-active area extending from the bending area and having a plurality of pad electrodes disposed therein, a pixel driving circuit disposed on the substrate and electrically connected to the plurality of pad electrodes, a plurality of insulating layers disposed on the pixel driving circuit, and a plurality of micro LEDs disposed on the plurality of insulating layers. A pressure applied to the connection line when the flexible circuit board is bonded is minimized or reduced and a pressure margin for bonding the pad electrodes and the flexible circuit board can be ensured.