Liquid Flow-Through Plate Bonding for Low-CTE Thermal Interfaces
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Solution Overview
Problem
Electronic device packages with liquid-cooled cold plates experience additional temperature rise due to coefficient of thermal expansion (CTE) differences at multiple material interfaces, which affect heat transfer efficiency.
Innovation Solution
A process involving metallizing a substrate with metal matrix composite (MMC) material, applying a braze foil, and executing a high-temperature and high-pressure bake to create a transient liquid-phase bond, eliminating the need for multiple material interfaces by using closely matched CTE materials like aluminum graphite and aluminum silicon-carbide composites, integrated with standard aluminum foil fins and braze alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If multiple material interfaces are used to account for CTE difference, then CTE mismatch is managed, but additional temperature rise occurs at each interface
Solution Approach 1:
The patent removes the intermediate material layers (thermal interface materials, underfills, adhesives) that create multiple interfaces between the electronic device layer and liquid-cooled cold plate. By directly bonding substrates with closely matched CTE values, it extracts the problematic intermediate layers that cause thermal resistance and temperature rise at interfaces.
Solution Approach 2:
The patent changes the CTE parameter matching between materials by selecting substrates with closely matched CTE values (e.g., aluminum graphite and aluminum silicon-carbide composites). This parameter matching eliminates the need for multiple compensating interfaces, thereby reducing thermal resistance and temperature rise while maintaining structural stability under thermal expansion differences.
2Loss of energy
If direct bonding of substrates is achieved, then heat transfer efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary metallization to the substrate surfaces before bonding, creating a metal-coated surface that enables direct brazing. This preliminary action prepares the surfaces in advance with appropriate bonding characteristics, allowing direct substrate-to-substrate bonding without intermediate layers, thereby improving heat transfer while managing manufacturing complexity through a standardized pre-treatment process.
Solution Approach 2:
The patent uses metal matrix composite (MMC) materials with closely matched CTE values for direct bonding. The composite material structure provides both mechanical strength and thermal conductivity while maintaining CTE compatibility, enabling direct bonding that improves heat transfer efficiency without requiring complex multi-layer assemblies.
3Strength
If metallization is applied to substrate surface, then bonding capability is enhanced, but surface depth increases
Solution Approach 1:
The patent applies metallization as a thin surface coating rather than through-the-depth treatment. The metallized layer provides sufficient bonding capability for direct brazing while maintaining a sub-micron depth that minimizes thermal resistance. This partial action approach applies the metallization functionally where needed at the surface without excessive penetration into the substrate.
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
Direct heat transfer from electronic devices to coolant is achieved without significant thermal rise, enhancing heat removal efficiency and reducing thermal effects in electronic device packages.
Implementation Method 1
the metallizing includes one of physical vapor deposition (PVD) and electroplating
Implementation Method 2
the metallizing includes electroplating
Implementation Method 3
executing a high-temperature and high-pressure bake whereby material of the braze foil diffuses into the metallized surface
Implementation Method 4
the executing of the high-temperature and high-pressure bake causes a transient liquid-phase bonding between the material of the braze foil and the metallized surface
Data Source
AI summary
A process for building a high-performance liquid flow-through plate is provided and includes providing a substrate formed of metal matrix composite (MMC) material, metallizing a surface of the substrate to reform the surface into a metallized surface, placing a braze foil on the metallized surface and executing a high-temperature and high-pressure bake whereby material of the braze foil diffuses into the metallized surface.