Buffered Ceramic Substrate for LED Heat Dissipation
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Solution Overview
Problem
High-efficiency LED products face significant heat dissipation challenges due to high thermal expansion coefficients in traditional substrates, leading to instability and reduced light intensity, which existing technologies like copper foil PCBs and direct bonded copper substrates fail to adequately address.
Innovation Solution
A ceramic substrate with a seed layer, a buffering material layer composed of metal and ceramic materials, and a copper circuit layer, where the buffering material layer's thermal expansion coefficient bridges the gap between the ceramic and copper, forming a gradient thermal expansion coefficient substrate for improved heat stability and compatibility in fine circuit manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If direct bonded copper (DBC) substrate is used, then heat dissipation capability is improved, but thermal expansion coefficient difference causes instability in heat circulation
Solution Approach 1:
An intermediate buffering layer is introduced between the copper circuit layer and the ceramic substrate. This buffering layer has a thermal expansion coefficient that is intermediate between copper and ceramic, serving as a mediator to gradually transition the thermal expansion stress and prevent sudden delamination or cracking, thereby maintaining heat circulation stability while preserving heat dissipation capability.
Solution Approach 2:
The substrate structure is designed as a composite material system consisting of copper circuit layer, buffering layer, and ceramic substrate. Each layer is selected with specific thermal expansion properties to create a gradient structure that manages thermal stress effectively, combining the heat dissipation advantage of copper with the stability of ceramic while mitigating their incompatibility.
2Ease of manufacture
If copper foil printed circuit board (PCB) is used, then manufacturing cost is reduced, but heat dissipation capability is insufficient for high-efficiency LED
Solution Approach 1:
The substrate is segmented into multiple functional layers: a copper circuit layer for electrical connectivity and heat dissipation, a buffering layer for thermal stress management, and a ceramic substrate for structural stability and additional heat dissipation. This segmentation allows each layer to be optimized for its specific function while working together to achieve both cost-effectiveness and superior heat dissipation.
Solution Approach 2:
Different regions of the substrate structure are assigned different material properties: the copper layer provides high thermal conductivity for heat dissipation, the buffering layer provides intermediate thermal expansion properties, and the ceramic substrate provides dimensional stability. This local differentiation of material qualities enables the substrate to simultaneously achieve low cost and high heat dissipation performance.
3Length of moving object
If direct plated copper (DPC) substrate is used, then circuit width can be reduced, but thermal expansion coefficient difference causes copper removal and electric leakage
Solution Approach 1:
The buffering layer acts as an intermediary between the copper circuit layer and the ceramic substrate, providing a gradual transition in thermal expansion coefficients. This prevents the sudden stress concentration that occurs in direct copper-ceramic bonding, thereby preventing copper removal, electric leakage, and other reliability issues even when using fine circuit widths.
4Strength
If high temperature co-fired ceramic (HTCC) is used, then product strength is improved, but manufacturing temperature is too high limiting electrode material selection
Solution Approach 1:
The copper circuit layer and buffering layer are prepared and bonded to the ceramic substrate at lower temperatures before final assembly. This preliminary action allows the use of temperature-sensitive electrode materials that would be damaged by HTCC processing temperatures, while the ceramic substrate still provides the necessary structural strength for the final product.
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 enhances heat stability and compatibility of copper circuits on ceramic substrates, reducing manufacturing costs and energy consumption while preventing delamination and cracking under high temperatures, making it suitable for high-efficiency LED and thermoelectric devices.
Implementation Method 1
The thermal expansion coefficient of the buffering material layer is between those of the ceramic substrate and the copper circuit layer
Data Source
AI summary
An electric conduction heat dissipation substrate includes a ceramic substrate, and a seed layer, and a buffering material layer and a copper circuit layer formed thereon in order. The buffering material layer has a coefficient of thermal expansion between those of the ceramic substrate and the copper circuit layer. Moreover, the buffering material layer is composed of alloy material and ceramic material or composed of metal material and ceramic material.