LED Chip Assembly on Composite Substrate for Heat Dissipation
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Solution Overview
Problem
Existing LED packages face challenges in heat dissipation due to the low thermal conductivity of monocrystalline sapphire substrates, leading to reduced light emission efficiency and shorter device lifetimes, especially in high-output LEDs, and the use of metal package substrates with high thermal expansion coefficients causes cracking and reduced heat dissipation.
Innovation Solution
An LED chip assembly is developed with LED chips directly mounted on a composite substrate made of an inorganic body infiltrated with aluminum or aluminum-silicon alloys, providing high thermal conductivity, controlled thermal expansion, and sufficient strength, along with a metal layer and insulation layer to enhance heat dissipation and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If monocrystalline sapphire substrate is used for LED chip mounting, then the LED chip can be mounted and basic electrical function is achieved, but heat dissipation is insufficient leading to reduced light emission efficiency and shorter device lifetime
Solution Approach 1:
The patent uses a composite substrate structure consisting of a sapphire layer bonded to a metal layer (such as copper or aluminum). The sapphire layer provides mechanical support and electrical insulation, while the metal layer provides high thermal conductivity for heat dissipation. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both structural integrity and effective heat management.
2Temperature
If metal package substrate is used to improve heat dissipation, then thermal conductivity is improved, but the high coefficient of thermal expansion causes cracking and reduces reliability
Solution Approach 1:
The composite substrate combines sapphire with low thermal expansion coefficients and high mechanical strength with metal layers that have high thermal conductivity. The sapphire layer acts as a stress-buffering component that compensates for thermal expansion mismatches, preventing cracking while maintaining effective heat dissipation through the metal layer.
Solution Approach 2:
The patent applies different material properties to different layers of the substrate structure. The sapphire layer provides mechanical stability and low thermal expansion, while the metal layer provides high thermal conductivity. This local differentiation of material functions allows the system to simultaneously achieve cracking resistance and heat dissipation without requiring a single material to satisfy all requirements.
3Reliability
If insulation layer is added under metal bonded portion to achieve electrical insulation, then electrical isolation is improved, but heat dissipation ability is reduced due to low thermal conductivity of insulation materials
Solution Approach 1:
The composite substrate structure integrates electrical insulation and heat dissipation functions within the same layered structure. The sapphire layer provides electrical insulation while the metal layer provides heat dissipation, eliminating the need for separate insulation layers that would impede thermal conduction. This integrated approach resolves the contradiction by combining insulating and thermally conductive properties in different layers of the same component.
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 significantly improves heat dissipation and reliability of LED packages, reducing illumination temperature and enhancing luminance, while minimizing the risk of cracking and maintaining high output performance.
Implementation Method 1
a composite substrate which is formed by infiltration of an inorganic formed body with aluminum, silicon or an alloy containing these components
Implementation Method 2
a thermal conductivity of 100 to 600 W/(m·k) at a temperature of 25 °C
Implementation Method 3
the bond by the bonding material is by soldering, brazing or adhesion by a high thermal conductivity adhesive
Implementation Method 4
the bond by the bonding material is by soldering, brazing or adhesion by a high thermal conductivity adhesive
Data Source
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AI summary
Provided is a highly reliable LED package with significantly improved heat radiating properties, manufacturing method of the LED package, and an LED chip assembly used in the LED package. The LED package is characterized in that the LED chip assembly (10) is bonded to a circuit board (11) created by forming metal circuitry (3) on a metal substrate (5) with an insulation layer (4) therebetween, whereas an LED chip (1) of the LED chip assembly and the metal circuitry (3) of the circuit board are connected via an electrical connection member (9), and at least the LED chip assembly and the electrical connection member are encapsulated with resin encapsulant (8) including fluorescent material.