Graphite Bar Cooling Assembly for High-Power Flip Chip Heat Transfer
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Solution Overview
Problem
Existing thermal management systems for high-power flip chip electronic components in space applications, such as heat pipes and thermal straps, are inefficient, costly, and complex, leading to potential failure and thermal fatigue, particularly in environments where maintenance is difficult, like on board a satellite.
Innovation Solution
A thermal management system using highly conductive graphite bars mounted to a frame with a receiving and retaining member, thermally coupled to a heat sink, and bonded with a flexible adhesive to flip chip electronic components, providing a efficient heat path and mitigating thermal fatigue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat pipes are used for thermal management, then heat transfer efficiency is improved, but device complexity and assembly difficulty increase
Solution Approach 1:
The patent extracts the complex heat pipe structure and replaces it with a simplified graphite bar thermal conductor. The graphite bar provides the necessary thermal conduction function without the complicated assembly requirements of heat pipes, including no need for vacuum sealing, wick structures, or phase change mechanisms.
Solution Approach 2:
The patent employs a simple, easily replaceable graphite bar that can be quickly installed and removed without extensive screening or complex assembly procedures. This approach trades the long-term durability of complex heat pipes for the ease of replacement and lower cost of simple graphite conductors.
2Reliability
If copper thermal straps are used, then thermal conductivity is improved, but mass increases significantly
Solution Approach 1:
The patent changes the material parameter from copper to graphite, which has comparable or superior thermal conductivity in the required direction while being significantly lighter. This material substitution maintains thermal performance while reducing mass penalty.
Solution Approach 2:
The patent uses graphite, a non-metallic material with exceptional thermal conductivity properties, to replace traditional metallic thermal straps. This composite material approach provides high thermal performance with reduced weight compared to copper or aluminum alternatives.
3Weight of moving object
If graphite strips are used, then mass is reduced, but thermal conductivity in specific directions deteriorates due to layer orientation
Solution Approach 1:
The patent transitions from two-dimensional graphite strips with orientation issues to three-dimensional graphite bars that provide omnidirectional thermal conduction. The bar geometry ensures thermal pathways in all required directions, eliminating the orientation sensitivity of planar graphite strips.
Solution Approach 2:
The patent applies graphite material strategically in a bar configuration that concentrates thermal conduction capability where needed, with the cylindrical or rectangular geometry providing uniform thermal properties in all radial directions while maintaining low mass.
4Ease of manufacture
If conventional thermal straps are used, then assembly is simplified, but thermal performance deteriorates
Solution Approach 1:
The patent uses graphite bars that combine the assembly simplicity of traditional thermal straps with the superior thermal conductivity of graphite material. The bar geometry provides structural rigidity and ease of mounting while delivering high thermal performance that conventional aluminum or copper straps cannot match at equivalent mass.
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 system achieves high thermal conductivity with low mass, simplifies assembly, reduces costs, and extends the operating life of electronic components by effectively managing thermal output, while overcoming the limitations of conventional methods.
Implementation Method 1
Heat is extracted from the at least one graphite bar or flows downward through the at least one graphite bar along the second axis to the receiving and retaining member, to the frame, and to the heat sink
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
A cooling apparatus is provided, including a graphite bar mounted to a frame, the graphite bar thermally conductive in perpendicular first and second axes, the second axis parallel to a length of the graphite bar, the frame for mounting the at least one graphite bar, the frame including a receiving and retaining member mounted thereon and thermally coupled thereto for retaining the graphite bar in a fixed position relative to the frame, the receiving and retaining member including a recess for receiving the graphite bar, a thermal adhesive disposed in the recess for adhering and thermally coupling the graphite bar to the receiving and retaining member, and a heat sink thermally coupled to the frame. Heat is extracted from the graphite bar or flows downward through the graphite bar along the second axis to the receiving and retaining member, to the frame, and to the heat sink.