Heat Exchanger Assembly With CTE-Matched Base and ECAM Fins
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Solution Overview
Problem
Conventional heat exchangers face limitations due to high thermal expansion coefficients (CTE) of materials like copper, leading to challenges in bonding with low-CTE materials, necessitating thick thermal interface materials (TIMs) that hinder thermal transfer and increase spacing, and limiting cooling capabilities.
Innovation Solution
Fabrication of heat exchangers using electrochemical additive manufacturing (ECAM) to create heat-exchanging portions with CTEs closer to the heat source, allowing direct fluid contact and minimizing the need for thick TIMs, by using materials like tungsten for the base and copper for the heat-exchanging portion, with varying compositions and geometries to manage CTE mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If copper is used for heat exchanger fins due to excellent thermal properties, then thermal conductivity is improved, but coefficient of thermal expansion mismatch with low-CTE materials (e.g., silicon) worsens, requiring thick thermal interface materials
Solution Approach 1:
The heat exchanger is divided into multiple segments with different materials: a base made of low-CTE material (e.g., silicon, silicon carbide, or diamond) and fins made of high-thermal-conductivity material (e.g., copper). This segmentation allows each component to be optimized for its specific function while reducing overall CTE mismatch with the heat source.
Solution Approach 2:
The heat exchanger uses composite construction combining materials with different properties - low-CTE base materials (silicon, silicon carbide, diamond) bonded to high thermal conductivity fin materials (copper). This composite approach resolves the contradiction by allowing thermal optimization in fins while maintaining dimensional stability at the interface.
2Reliability
If thick thermal interface materials are used to accommodate CTE mismatch, then bonding reliability is improved, but thermal transfer efficiency worsens due to increased thermal resistance
Solution Approach 1:
The invention changes the CTE parameter of the base material from high (copper) to low (silicon, silicon carbide, or diamond), matching the heat source CTE more closely. This parameter change allows for thinner thermal interface materials while maintaining bonding reliability under thermal cycling, thereby reducing thermal resistance.
3Ease of manufacture
If conventional manufacturing methods (extrusion, stamping, die casting) are used, then manufacturing simplicity is improved, but geometric flexibility and material selection worsen, limiting cooling capabilities
Solution Approach 1:
The heat exchanger features local quality variations with non-linear channel geometries and varying fin configurations optimized for specific thermal management requirements. The base and fins can have different material compositions and structural characteristics tailored to their respective functional needs.
Solution Approach 2:
The invention transitions from conventional linear/parallel fin geometries to non-linear, three-dimensionally optimized channel structures. The heat exchanger incorporates complex curved pathways and varying cross-sections that maximize surface area and thermal efficiency while accommodating space constraints.
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
Enhances thermal transfer efficiency and reduces mechanical stress, enabling high-performance cooling with minimal thermal resistance and improved adhesion, even under temperature fluctuations.
Implementation Method 1
selectively activating an electrode subset from the set of pixelated electrodes using a set of electrode-array drivers thereby generating an ionic flow through the electrolyte between the electrode subset and a portion of the deposition surface aligned with the electrode subset thereby electrochemically depositing a heat-exchanging portion
Data Source
AI summary
Described herein are methods of fabricating heat exchangers and heat source assemblies using electrochemical additive manufacturing (ECAM). A method may comprise submerging a build plate (e.g., a base and/or a heat source) and a printhead into an electrolyte and selectively activating an electrode subset of the printhead thereby electrochemically depositing a heat-exchanging portion. In the final assembly, the average coefficient of thermal expansion (CTE) of the base is closer to that of the heat source than the average CTE of the heat-exchanging portion. The combination of the heat-exchanging surfaces and the base forms openings (e.g., non-linear channels) for directing a heat transfer fluid through the heat exchanger. The openings may extend to the base and/or to the heat source for direct contact. For example, any dimension of each extension end may be less than a critical dimension, determined by adhesion, CTE mismatch, and temperature fluctuations.