Diamond-Copper Heat Sink Composite for Corrosion-Resistant Plating
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Solution Overview
Problem
Existing composite materials for heat sinks, such as diamond-metal composites, face challenges in achieving high thermal conductivity and strength, particularly after nickel electroplating treatments, due to corrosion and reduced thermal conductivity, which affects their performance and longevity in semiconductor devices.
Innovation Solution
A composite material comprising diamond particles, copper, and specific elements like silicon, chromium, cobalt, nickel, molybdenum, titanium, vanadium, niobium, tantalum, tungsten, and aluminum, with the latter elements concentrated at interfaces to enhance corrosion resistance and maintain high thermal conductivity and strength even after nickel electroplating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If copper is used as heat sink material, then thermal conductivity is improved, but thermal expansion coefficient mismatch with semiconductor generates large thermal stress
Solution Approach 1:
The patent uses a composite material consisting of diamond particles dispersed in a copper matrix. Diamond has low thermal expansion coefficient similar to semiconductors, while copper provides high thermal conductivity. The composite structure combines the advantages of both materials, achieving thermal conductivity of 400 W/mK or more while reducing thermal expansion coefficient to 6.0 ppm/K or less, thus solving the thermal stress problem.
2Use of energy by stationary object
If diamond is used as heat sink material, then thermal conductivity is improved, but thermal expansion coefficient is too low causing large thermal stress with semiconductor
Solution Approach 1:
The patent creates a composite where diamond particles (low thermal expansion) are embedded in a copper matrix (high thermal expansion). This composite structure achieves an intermediate thermal expansion coefficient (6.0 ppm/K or less) that is compatible with semiconductors, while maintaining high thermal conductivity (400 W/mK or more) through the diamond particles and copper matrix.
3Reliability
If nickel electroplating is applied to diamond-copper composite, then corrosion resistance is improved, but thermal conductivity decreases due to copper corrosion
Solution Approach 1:
The patent optimizes the content ratio of diamond particles to copper to 60:40 or more by volume, ensuring sufficient copper content (10-40% by volume) to maintain thermal conductivity pathways even after nickel plating. This parameter optimization ensures that thermal conductivity remains 400 W/mK or more while achieving corrosion resistance through nickel electroplating.
4Reliability
If alloying copper with low thermal expansion materials is done, then thermal expansion coefficient is improved, but thermal conductivity decreases
Solution Approach 1:
The patent uses a composite material structure where diamond particles (providing low thermal expansion) are dispersed in a copper matrix (providing high thermal conductivity). This differs from alloying by maintaining copper's inherent high thermal conductivity while incorporating diamond particles that reduce the overall thermal expansion coefficient to 6.0 ppm/K or less, achieving both goals simultaneously.
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 composite material achieves high thermal conductivity and strength, ensuring excellent performance and long service life for heat sinks and semiconductor devices by suppressing copper corrosion during electroplating and maintaining thermal conductivity above 400 W/mK.
Implementation Method 1
diamond particles... high thermal conductivity of 1,000 W/mK or higher
Implementation Method 2
copper... high thermal conductivity
Implementation Method 3
the first element is concentrated at interfaces between the diamond particles and the copper such that the concentration of the first element in the ranges where the distance from the interface is 1 nm or larger and 30 nm or smaller is higher by 50% or higher than the concentration of the first element in the diamond region and the copper region
Implementation Method 4
copper... large thermal expansion coefficient as compared with typical semiconductors... thermal expansion coefficients closer to those of the semiconductors
Data Source
Figure 1~2
Figure 3~5
AI summary
A composite material of the present disclosure contains a plurality of diamond particles, copper, and at least one first element selected from the group consisting of silicon, chromium, cobalt, nickel, molybdenum, titanium, vanadium, niobium, tantalum and tungsten, wherein the content rate of the first element based on the total mass of the copper and the first element is 50 ppm or higher and 2,000 ppm or lower.