LED Thermal Management via Water-Soluble Paste and Metal Block
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Solution Overview
Problem
LEDs face significant heat dissipation challenges due to high thermal resistance, particularly in large power applications, where heat generation is substantial, leading to reduced luminous flux and shortened service life, primarily attributed to the low thermal conductivity of sapphire substrates and inadequate die bonding materials like M2 glue.
Innovation Solution
A light-emitting device design featuring a water-soluble high thermal conductivity paste as die bonding material, a metal blocking layer to prevent solder paste damage, and a thin metal block for enhanced heat conduction, forming an all-metal thermal conducting path to reduce thermal resistance and improve reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sapphire substrate is used for LED chip mounting, then the LED structure is simplified and manufacturing is easier, but the thermal conductivity is low (0.2 W/mK for M2 glue) which impedes heat dissipation and increases thermal resistance
Solution Approach 1:
The patent changes the thermal conductivity parameter of the bonding material by replacing conventional M2 glue (0.2 W/mK) with high thermal conductivity paste (5-10 W/mK), directly addressing the thermal resistance issue while maintaining the sapphire substrate's manufacturing advantages
Solution Approach 2:
The patent uses composite material structures including metal blocks (aluminum or copper) with high thermal conductivity bonded to the sapphire substrate, creating a hybrid thermal management system that combines the ease of sapphire manufacturing with superior heat dissipation capabilities
2Ease of manufacture
If conventional die bonding paste like M2 glue is used, then the bonding process is simple, but the thermal conductivity is low (0.2 W/mK) which significantly reduces heat dissipation capacity
Solution Approach 1:
The patent changes the thermal conductivity parameter from 0.2 W/mK (M2 glue) to 5-10 W/mK (high thermal conductivity paste), dramatically improving heat dissipation while maintaining processability through optimized paste formulation
Solution Approach 2:
The high thermal conductivity paste acts as an intermediary material between the LED chip and the metal block, facilitating efficient heat transfer while maintaining reliable electrical and mechanical bonding
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
The solution effectively reduces thermal resistance to less than 7 K/W, enhances heat dissipation, and increases the reliability of LEDs, allowing for larger light-emitting areas and cost savings, while being suitable for large power applications.
Implementation Method 1
LED heat is mainly dissipated through heat conduction, and its heat dissipation capacity is determined by thermal resistance
Implementation Method 2
the side approximate to the base has a reflecting structure
Data Source
AI summary
A light-emitting device includes a base having an insulating part and a metal block; a light-emitting diode (LED) chip over the base; a water soluble paste between the LED chip and the base metal block for chip fixing and heat conduction; packaging glue covering the LED chip; and the LED chip bottom, water soluble paste and the base metal block form an all-metal thermal conducting path to achieve low a thermal resistance.