Stacked Micro-LED Chip Package for Easier Transfer and Color Purity
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Solution Overview
Problem
The challenge in manufacturing micro-LED displays lies in the complexity and time-consuming process of mounting hundreds of thousands or millions of small LED chips, which requires a significant area and is prone to handling difficulties due to their small size and vulnerable structure, leading to issues with brightness and color purity.
Innovation Solution
A light emitting chip with a stacked structure is developed, featuring a passivation layer and connection electrodes that cover the sides of the LED sub-units, allowing for easier handling and transfer, and removing the growth substrate to enhance light efficacy and color purity by reducing the substrate's impact on light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If individual LED chips are arranged on a two-dimensional plane for each sub-pixel, then color display capability is achieved, but the number of LED chips required becomes very large and the mounting process becomes complex and time-consuming
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of individual LED chips to a three-dimensional stacked structure. Multiple LED chips emitting different colors (blue, green, red) are vertically stacked on a single substrate, enabling full-color display while reducing the number of chips required from hundreds of thousands to a much smaller quantity.
2Area of moving object
If micro-LED chips are made very small to increase display resolution, then display density is improved, but handling and transfer become difficult due to vulnerable structure
Solution Approach 1:
The patent segments the handling function from the micro-LED chips themselves by introducing a carrier substrate that supports multiple stacked chips. The carrier substrate provides mechanical strength and facilitates handling, while the individual micro-LED chips maintain their small size for high display resolution.
Solution Approach 2:
The patent creates a composite structure combining multiple LED chips with different materials (GaN-based blue LED, phosphor materials for green and red emission) stacked vertically. This composite structure achieves full-color emission from a single compact unit, improving both resolution and handling characteristics.
3Strength
If growth substrate is retained in the LED chip structure, then structural support is provided, but light efficacy and color purity are reduced due to substrate interference
Solution Approach 1:
The patent extracts and removes the growth substrate from the final LED chip structure after the stacked LEDs are formed. This extraction eliminates substrate interference that would otherwise reduce light efficacy and color purity, while the stacked configuration provides sufficient structural support without requiring the original growth substrate.
Data Source
AI summary
A light emitting package includes a first LED sub-unit having first and second opposed surfaces, a second LED sub-unit disposed on the second surface of the first LED sub-unit, a third LED sub-unit disposed on the second LED sub-unit, a plurality of connection electrodes having side surfaces and electrically connected to at least one of the LED sub-units, the connection electrodes covering a side surface of at least one of the LED sub-units, a first passivation layer surrounding at least the sides surfaces of the connection electrodes, the first passivation layer exposing at least a portion of the first surface of the first LED sub-unit, a substrate having first and second opposed surfaces, with the first surface of the substrate facing the LED sub-units, and a first electrode disposed on the first surface of the substrate and connected to at least one of the connection electrodes.