Cu-Mo Heat Spreader Thickness Optimization for Thermal Stress
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Solution Overview
Problem
Conventional heat spreaders with stacked structures struggle to efficiently and immediately remove heat from high-performance elements due to limitations in heat conductivity and thermal expansion coefficient matching, leading to potential overheating and mechanical stress issues.
Innovation Solution
A heat spreader with a Cu-Mo layer of average thickness ≤0.6 mm and variation ≤0.1 mm, combined with a Cu layer directly stacked on both surfaces, enhances heat conductivity and minimizes thermal stress by improving bonding strength and maintaining continuity, while a manufacturing method involving planarization and roll-bonding ensures efficient production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional heat spreader with stacked structure is used, then thermal expansion coefficient matching is improved, but heat conductivity is insufficient leading to inefficient heat removal
Solution Approach 1:
The patent changes the thickness parameter of the Cu-Mo layer to ≤0.6mm to optimize the balance between thermal expansion matching and heat conductivity. This parameter adjustment allows the heat spreader to maintain low thermal expansion coefficient for reliability while improving heat removal efficiency through reduced thermal resistance in the thickness direction.
Solution Approach 2:
The patent uses a Cu-Mo composite material with specific composition ratios to achieve both low thermal expansion coefficient (for reliability) and high heat conductivity. The composite structure combines the low thermal expansion properties of Mo with the high heat conductivity of Cu, resolving the contradiction between these two properties.
2Reliability
If the Cu-Mo layer thickness is increased to improve thermal expansion matching, then reliability is improved, but heat removal efficiency deteriorates
Solution Approach 1:
The patent optimizes the thickness parameter of the Cu-Mo layer to be ≤0.6mm, which is thin enough to maintain high heat removal efficiency (reducing thermal resistance) while still providing sufficient thermal expansion coefficient matching. This precise parameter control resolves the contradiction between reliability and temperature management.
3Adaptability or versatility
If the heat spreader is downsized to accommodate high-performance elements, then adaptability is improved, but heat removal capability may deteriorate
Solution Approach 1:
The patent reduces the thickness parameter of the Cu-Mo layer to ≤0.6mm, which downsizes the heat spreader structure to accommodate high-performance elements while simultaneously improving heat removal capability by reducing thermal resistance. This parameter optimization ensures that downsizing does not compromise heat removal efficiency.
Solution Approach 2:
The patent employs Cu-Mo composite material that provides high heat conductivity in a compact thickness, enabling the heat spreader to be downsized for adaptability to high-performance elements while maintaining or even improving heat removal capability through the superior thermal properties of the composite material.
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 spreader effectively removes heat more efficiently and immediately, addressing overheating and mechanical stress concerns, and can be downsized to accommodate increased performance and output demands of various apparatuses.
Implementation Method 1
By providing the Cu-Mo layer, the thermal expansion coefficient of the heat spreader can be decreased to be less than that of a conventional heat spreader entirely made of a metal or an alloy, and can be brought closer to the thermal expansion coefficient of the element or the ceramic substrate as much as possible. That is, matching between the thermal expansion coefficients thereof can be achieved. This can prevent an excessive stress from being applied to the element or the ceramic substrate based on the difference in thermal expansion coefficient, under a thermal load environment such as a hot-cold cycle
Implementation Method 2
a Cu layer which is directly stacked on each of both surfaces of the Cu-Mo layer... Cu is used together with Mo because the heat conductivity of Mo alone is insufficient and thus Cu is additionally used to prevent a decrease in the heat conductivity of the heat spreader
Data Source
Figure 1~2
AI summary
[Problem] To provide a heat spreader capable of removing heat from an element more efficiently and immediately than an existing one, and also capable of satisfactorily responding to further enhancement in performance and output of various apparatuses, and a method for efficiently manufacturing the same. [Solution] A heat spreader includes a Cu-Mo layer made of a Cu-Mo composite material and having an average thickness of less than or equal to 0.6 mm and a variation in thickness of less than or equal to 0.1 mm, and a Cu layer directly stacked on each of both surfaces thereof. A method for manufacturing the heat spreader includes planarizing a plate material of the Cu-Mo composite material constituting the Cu-Mo layer, and roll-bonding a Cu plate constituting the Cu layer to each of both surfaces thereof.