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Novel Thermal Management Materials Technologies for High Power Naval Systems

Description:

TECHNOLOGY AREA(S): Materials, Electronics 

OBJECTIVE: To develop advanced electrically insulating materials for improved passive thermal management of high-power electronics. The goal is to have materials that will improve both performance and efficiency, lengthen lifetime, and reduce lifecycle costs with enhanced thermal conductivity while remaining electrically insulating. Advanced materials that can lower junction temperatures within individual components, and those that serve as adhesives, pastes, underfills, and top side coating for attaching components into systems or covering components is the area of interest. 

DESCRIPTION: As circuits become smaller and denser, performance, efficiency, and lifetime of high-power electronics increasingly depends on rapid conduction of heat away from semiconductor junctions in the components. Without better ways for heat to escape, higher junction temperatures dramatically reduce performance of critical equipment, stress any system batteries, diminish efficiency and lifetime, and increase lifecycle maintenance and replacement costs. Navy-relevant electronic components include power conversion devices such as diodes and transistors used in almost every power supply, power converter, and many alternating current/direct current (AC/DC) components, used in combat systems, sensors on land and at sea, and components in high-temperature environments. Radio frequency (RF) systems used in radar, communications, and even Wi-Fi, all rely on RF diodes and transistors that are frequently pushed to their maximum performance limit, generating performance-degrading heat. The current state-of-the-art for insulators is dielectric material typically made from polymers or rubber, which can catch fire easily and degrade over time. Currently, polymers composited with materials such as boron nitride and diamond powders are often used. The research proposed should be to expand on the types of materials being composited with the polymers to including but not limited to materials such as boron nitride nanotubes, boron nitride nanosheets, boron carbide powders, and aluminum nitride to achieve cost-effective and manufacturable processes with enhanced thermal conductivity while remaining electrically insulating. Successfully cooling of components and systems requires both electrically insulating and electrically conductive passive heat transport. The focus for the proposed research is on the electrically insulating materials. 

PHASE I: Develop samples of material that demonstrate enhanced thermal conductivity for one or more applications of electrically insulating materials appropriate for high-power electronics in areas such as within individual components, and those that serve as adhesives, pastes, underfills, and top-side coatings for attaching components into systems or covering components. The desired gap between the component and the board for paste application is within the thickness range of 50-1000 microns. The thermal sheet size should be approximately 6-8 cm^2, and the thickness goal is 1000 microns. The desired thermal conductivity for thermal pastes, adhesives, and pads is >8 W/mK. For topside thermal coatings and electronic component inner layers, the desired thermal conductivity is >2 W/mK. The performer should test the performance of these materials with commercially available testing equipment or equivalent in-house testing apparatus. Measurements up to one hundredth of a degree Celsius using Infrared thermography can be used to test thermal conductivity. Other equivalent methods are acceptable. The desired threshold requirement for this topic is 10 W/mK. The offeror will investigate and recommend the appropriate manufacturing process, provided it yields high-quality materials at low cost with the desired properties. Proposals that include thermal sheets must be designed to have the correct thickness and contact resistance, depending on the application. Proposals that include a coating that cannot be applied to all of the items listed above, such as a paste, are acceptable. Phase I will include the creation of prototype plans to be developed in Phase II. 

PHASE II: Fabricate prototype components or assemblages of components that demonstrate the improved thermal performance such as within individual components, and those that serve as adhesives, pastes, underfills, and top side coating for attaching components into systems or covering components. The offeror will quantify vibration, thermal expansion, volumetric expansion, density change, and shrinkage, and these results will be compared to known industry standards. The prototype components must simulate the thermal properties of actual components, such as polymers, used for insulating laser diodes. The performer should test the performance of these components or assemblages of components. Performance will be measured relative to current performance parameters for junction materials. 

PHASE III: Deliver field testable systems to the Navy of components or assemblages of components and demonstrate that manufacturable processes are available for cost-effective deployment of systems at scale. Cost effectiveness will be evaluated relative to the cost of the current state-of-the-art. Dual use applications include electric power supplies and conversion, high-power radio frequency generation, high-power processors, and satellite electronics cooling. 

REFERENCES: 

1: Hingyi Huang, Pingkai Jiang, Toshikatsu, "A review of dielectric polymer composites with high thermal conductivity," IEEE Electrical Insulation Magazine (27), July-August 2011, DOI: 10.1109/MEI.2011.5954064

2:  2Hongli Zhu,† Yuanyuan Li,† Zhiqiang Fang,† Jiajun Xu,‡ Fangyu Cao,‡ Jiayu Wan,† Colin Preston,†Bao Yang,‡,* and Liangbing Hu‡,"Highly Thermally Conductive Papers with Percolative Layered Boron Nitride Nanosheets", ACS Nano, 2014

3:  Han, Z. and Fina, A. "Thermal Conductivity of Carbon Nanotubes and Their Polymer Nanocomposites: A Review." Prog. Polym. Sci. 2011, 36, 914–944

4:  Chen, S., FitzGerald, J., Williams, J. and Bulcock, S. "Synthesis of Boron Nitride Nanotubes at Low Temperatures Using Reactive Ball Milling", Chemical Physical Letters, Vol. 299, Issues 3- 4, January 11, 1999, Pages 260-264.

KEYWORDS: High Power Electronics; Thermally Conductive Electrically Insulating Composites; Adhesives; Underfills; Top Side Coatings 

CONTACT(S): 

Sarwat Chappell 

(703) 696-4224 

sarwat.chappell@navy.mil 

Quentin Saulter 

(703) 696-2594 

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