Cu-Mo Clad Heat Sink Structure for Thermal Expansion and Heat Flow
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Solution Overview
Problem
Existing heat sinks for semiconductor elements lack optimal thermal properties, specifically high thermal conductivity in the thickness direction and low coefficient of thermal expansion, which are crucial for high-output and compact semiconductor modules.
Innovation Solution
A heat sink with a clad structure of three or more Cu layers and two or more Cu-Mo composite layers alternately stacked, where the outermost Cu layers are thinner than intermediate Cu layers, and manufactured through diffusion bonding and rolling, enhancing thermal conductivity and reducing thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a Mo-Cu composite material is used as a heat sink, then the coefficient of thermal expansion is reduced, but the thermal conductivity in the thickness direction is insufficient
Solution Approach 1:
The patent uses a composite structure combining Mo-Cu composite material layers with pure Cu layers. The Mo-Cu layers provide low thermal expansion coefficient while the Cu layers provide high thermal conductivity. This composite structure resolves the contradiction by allowing each material to contribute its advantageous property in the overall heat sink performance.
Solution Approach 2:
The patent creates a multi-layered clad structure with alternating Mo-Cu and Cu layers stacked in the thickness direction. This dimensional arrangement allows heat to conduct efficiently through the Cu layers while the Mo-Cu layers constrain thermal expansion, effectively resolving the property contradiction through spatial organization.
2Volume of moving object
If the heat sink is made compact to reduce size, then the area is reduced, but the thermal conductivity in the thickness direction becomes more critical and harder to achieve
Solution Approach 1:
The heat sink is segmented into multiple thin layers (Mo-Cu and Cu alternating layers) rather than using a single thick material. This segmentation allows the total thickness to be reduced for compactness while maintaining high thermal conductivity through the Cu layers, effectively resolving the contradiction between size reduction and thermal performance.
3Stability of the object's composition
If warm rolling is performed to manufacture the Mo-Cu composite material, then the coefficient of thermal expansion is reduced, but the manufacturing complexity increases
Solution Approach 1:
The patent applies warm rolling at specifically controlled temperatures (200-400°C) to the Mo-Cu composite material to reduce its coefficient of thermal expansion. By controlling the temperature parameter within this range, the material achieves desired thermal stability without requiring excessive manufacturing complexity, as the temperature window is well-defined and achievable.
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 heat sink achieves higher thermal conductivity and lower thermal expansion, particularly in the thickness direction, while maintaining stability and low manufacturing costs.
Implementation Method 1
manufactured through diffusion bonding and rolling
Implementation Method 2
each of the Cu-Mo composite layers has a thickness section microstructure in which flat Mo phase is dispersed in a Cu matrix
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
Provided is a heat sink that has a clad structure of a Cu-Mo composite material and a Cu material and has a low coefficient of thermal expansion and high thermal conductivity. A heat sink comprises three or more Cu layers and two or more Cu-Mo composite layers alternately stacked in a thickness direction so that two of the Cu layers are outermost layers on both sides, wherein each of the Cu-Mo composite layers has a thickness section microstructure in which flat Mo phase is dispersed in a Cu matrix. The heat sink has a low coefficient of thermal expansion and also has high thermal conductivity in the thickness direction because the thickness of each of the Cu layers which are the outermost layers is reduced, as compared with a heat sink of a three-layer clad structure having the same thickness and density.