Micro LED Module Planarization Layer Height Compensation
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Solution Overview
Problem
The challenge lies in the difficulty of directly disposing micro light-emitting devices on circuit substrates with significant height differences, which can lead to damage and instability during connection, due to the small size and high precision required.
Innovation Solution
A micro light-emitting device module is designed with a planarization layer on the circuit substrate, reducing the height difference and providing a stable surface for the micro light-emitting device, along with a conductive structure that includes pads with varying materials and sizes to enhance electrical connection and mechanical support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a micro light-emitting device is directly disposed on a circuit substrate with significant height differences, then the device can be connected to the substrate, but the connection becomes unstable and the device is at risk of damage due to the height difference
Solution Approach 1:
A planarization layer is introduced as an intermediary between the circuit substrate and the micro light-emitting device. This planarization layer fills the height differences and uneven surfaces of the circuit substrate, providing a flat and stable placement surface for the micro light-emitting device, thereby eliminating the connection instability and damage risks caused by direct placement on uneven substrates
Solution Approach 2:
The planarization layer is formed in advance on the circuit substrate before the micro light-emitting device is disposed. This preliminary action of creating a flat surface ensures that subsequent device placement and connection processes can proceed smoothly without the complications of height differences, improving both reliability and ease of operation
2Adaptability or versatility
If the planarization layer has a large maximum height difference on its second surface, then it can accommodate circuit substrate unevenness, but the micro light-emitting device may become unstable during placement
Solution Approach 1:
The planarization layer exhibits different height characteristics at different locations: it has greater height on its second surface (facing the circuit substrate) to accommodate substrate unevenness, while maintaining a relatively flat first surface (facing upward) for stable device placement. This local differentiation of height properties allows the planarization layer to simultaneously adapt to substrate variations and provide stable device support
3Reliability
If pads are made with varying materials and sizes, then electrical connection and mechanical support are enhanced, but the conductive structure becomes more complex
Solution Approach 1:
Different pads within the conductive structure are made with varying materials and sizes according to their specific functional requirements. First pads have different material compositions and dimensions than second pads, allowing each pad to be optimized for its particular electrical and mechanical demands, thereby enhancing overall connection reliability while maintaining a manageable level of structural complexity
Data Source
AI summary
A micro light-emitting device module includes a circuit substrate, a planarization layer and a micro light-emitting device. The planarization layer is disposed on an upper surface of the circuit substrate and has a first surface and a second surface opposite to each other. The second surface is in contact with the upper surface of the circuit substrate. The micro light-emitting device is disposed on the first surface of the planarization layer. A maximum height difference of the second surface of the planarization layer is greater than a thickness of the micro light-emitting device.