Flip LED Chip Trench Contact Structure for Thermal Management
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Solution Overview
Problem
Existing light emitting diode (LED) chips face challenges in heat dissipation due to the propagation of heat through substrates when assembled to printed circuit boards, which affects their performance and efficiency.
Innovation Solution
A method of fabricating flip LED chips involves growing an epitaxial structure on a substrate, depositing a conductive and reflective layer, forming trenches to create spatially separated contact pads, and assembling these chips onto metal core printed circuit boards with a mesa structure or dielectric thermal-conductive material for enhanced heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat emitting diode chips are wired bonded to printed circuit boards, then electrical connection is achieved, but heat dissipation is poor due to heat propagation through substrate
Solution Approach 1:
The patent segments the contact pads into multiple separate pads (first contact pad and second contact pad) that are spatially separated by a second trench. This segmentation allows for separate electrical connections to the metal core printed circuit board, creating multiple thermal pathways that improve heat dissipation while maintaining electrical connectivity.
Solution Approach 2:
The patent transitions from a planar lateral structure to a three-dimensional vertical structure by forming trenches that extend through multiple layers (from conductive and reflective layer down to first layer). This dimensional change enables direct vertical thermal and electrical pathways to the metal core printed circuit board, significantly improving heat dissipation efficiency.
2Reliability
If contact pads are formed on conductive and reflective layer, then electrical connection is established, but contact resistance is high
Solution Approach 1:
The patent merges the electrical connection function with the thermal management function by integrating the contact pads directly with the metal core printed circuit board through vertical trenches. This consolidation creates low-resistance electrical pathways that simultaneously serve as efficient thermal conduction paths, reducing contact resistance and enabling higher driving currents.
3Temperature
If trenches are formed to separate contact pads, then heat dissipation is improved, but manufacturing complexity increases
Solution Approach 1:
The patent performs preliminary actions by forming the trenches and depositing conductive materials during the semiconductor fabrication process itself, before the chip is assembled to the printed circuit board. This preliminary structuring of thermal and electrical pathways simplifies the overall manufacturing process by integrating multiple functions into the chip fabrication stage rather than requiring complex post-assembly modifications.
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 contact resistance, increases driving current, and accelerates heat dissipation from the LED chips to the printed circuit boards, improving the overall performance and efficiency of the LED devices.
Implementation Method 1
depositing a conductive and reflective layer on the epitaxial structure
Implementation Method 2
The second contact pad electrically connects the first layer by filling the conductive material in the first trenches
Implementation Method 3
assembling these chips onto metal core printed circuit boards with a mesa structure or dielectric thermal-conductive material for enhanced heat dissipation
Data Source
AI summary
A method of fabricating a light emitting diode device comprises providing a substrate, growing an epitaxial structure on the substrate. The epitaxial structure includes a first layer on the substrate, an active layer on the first layer and a second layer on the active layer. The method further comprises depositing a conductive and reflective layer on the epitaxial structure, forming a group of first trenches and a second trench. Each of the first and second trenches extends from surface of the conductive and reflective layer to the first layer to expose part of the first layer. The method further comprises depositing conductive material to cover a portion of the conductive and reflective layer to form a first contact pad, and cover surfaces between adjacent first trenches to form a second contact pad. The second contact pad electrically connects the first layer by filling the conductive material in the first trenches.