Direct-to-Component Heat Exchanger for CTE Mismatch Relief
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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, requiring thick thermal interface materials (TIMs) that hinder thermal transfer and increase spacing, and limited cooling capabilities.
Innovation Solution
Heat exchangers are fabricated using electrochemical additive manufacturing (ECAM) with a base and heat-exchanging portion made from materials with different CTEs, allowing direct fluid interface and minimizing CTE mismatch, thereby reducing the need for thick TIMs and enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If copper is used for heat exchanger fins due to excellent thermal properties, then thermal transfer performance is improved, but CTE mismatch with low-CTE materials (e.g., silicon) causes bonding challenges and requires thick TIMs
Solution Approach 1:
The heat exchanger is divided into multiple material sections: a low-CTE base material (e.g., silicon or silicon carbide) for bonding to the heat source, and copper fins for thermal transfer. This segmentation allows each part to be optimized for its specific function while minimizing CTE mismatch issues at the bonding interface.
Solution Approach 2:
Different parts of the heat exchanger use different materials with locally optimized properties: the base portion uses low-CTE material matching the heat source, while the fin portions use high thermal conductivity copper. This local quality approach resolves the contradiction by having material properties vary according to functional requirements.
2Reliability
If thick TIMs are used to accommodate CTE mismatch, then bonding reliability is improved, but thermal transfer efficiency deteriorates due to increased spacing and thermal resistance
Solution Approach 1:
The invention changes the CTE parameter of the base material to match the heat source (e.g., using silicon or silicon carbide with CTE similar to silicon processors). This parameter change eliminates the need for thick TIMs while maintaining bonding reliability, as the CTE mismatch is minimized at the interface.
3Ease of manufacture
If conventional manufacturing methods (extrusion, stamping, die casting) are used, then manufacturing ease is improved, but design flexibility and cooling capability are limited
Solution Approach 1:
The invention replaces conventional mechanical manufacturing methods (extrusion, stamping, die casting) with electrochemical additive manufacturing (ECAM). This substitution enables complex geometries, variable cross-sections, and integrated fluid channels that cannot be achieved with traditional methods, while still maintaining manufacturing feasibility.
Solution Approach 2:
The heat exchanger uses composite construction with different materials (low-CTE base material and copper fins) joined together through ECAM. This composite approach combines the advantages of different materials while enabling complex geometries that would be difficult or impossible to achieve with single-material conventional manufacturing.
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 solution reduces mechanical stress and improves thermal transfer by matching CTEs, enabling high-performance cooling without thick TIMs, thus enhancing heat exchanger performance and efficiency.
Implementation Method 1
heat-exchanging extensions, wherein the heat-exchanging extensions comprise heat-exchanging surfaces, a combination of the heat-exchanging surfaces and the base forms opening for flowing a heat transfer fluid through the heat exchanger
Implementation Method 2
Heat exchangers are fabricated using electrochemical additive manufacturing (ECAM)
Data Source
AI summary
Described herein are heat exchangers and heat source assemblies, which may be fabricated using electrochemical additive manufacturing (ECAM). A heat exchanger comprises a support structure and a conductive seed layer having a different composition than the support structure and forming a heat-transferring surface on the heat source. The heat exchanger further comprises a heat-exchanging portion comprising heat transfer extensions. The heat transfer extensions comprise first extension ends, second extension ends, and sidewalls extending between the first extension ends and the second extension ends and forming an opening for circulating a heat transfer fluid through the heat exchanger. The first extension ends are electrochemically deposited to the heat-transferring surface and form a heat-exchanging surface. Any dimension of each extension end may be less than a critical dimension, determined by adhesion, CTE mismatch, and temperature fluctuations.