Cost Savings & Predictable Performance Benefits of Carbon Nanotube Satellite Thermal Interface Solutions

Abstract

We present an analysis of the cost savings and performance benefits delivered by a predictable carbon-nanotube-based thermal gasket -Carbice® Space Pad™, for spacecraft builds. We show a >60% net savings in the Assembly Integration & Test (AI&T) and Thermal cost in a typical satellite build, supported by an independent analysis performed by a large space prime. Based on this analysis, a projected $1.13 billion in cost savings for Department of Defense's Satcom budget may be extracted by using carbon nanotube-based gaskets for all satellite assembly interfaces. This carbon-nanotube-based thermal gasket delivers valuable labor cost savings and performance improvement by taking advantage of a unique combination of excellent thermal properties and mechanical properties as a result of its structure - vertically aligned carbon nanotube forests bonded to both sides of an Aluminum core. The aligned carbon nanotubes not only provide high through-plan thermal conductivity, but their elasticity also allow reliable thermal contact during cycling, providing low thermal resistance in application. The Aluminum core keeps nanotubes intact, enables a form factor that is easy-to-use and fully reworkable, while contributing to in-plane thermal conductivity. The resulted thermal gasket is operable over a wide range of interface pressures, ranging from very low pressure up to over 1000 psi. This combination of thermal and mechanical properties allows satellite designers to incorporate full functionality into the system payload without the limitation of existing thermal solutions. There are two classes of materials that dominate spacecraft interfaces today: liquid solutions like particle laden silicone RTV and gap pads like graphite or particle laden gap fillers. RTV has a low thermal conductivity, limiting its ability to remove heat from on board electronics. Furthermore, their application process is time consuming (and therefore costly) when accounting for the time needed to prep surfaces, mix, precisely apply and cure the material. After curing, RTV is not reworkable, so when components must be removed from after initial testing it must be scraped manually from the flight vehicle and the underlying surfaces often need to be re-polished. Furthermore, this scraping process can generate conductive foreign object debris hazards. Gap pads like graphite or particle laden gap fillers come in the form of gaskets that can be cut to size reducing some of the installation burden. However, these materials suffer from irreversible compression set after installation. As a result, the gap pads can lose preload or in some cases dewet entirely from the interface as it expands and contracts thermally. This three-factor combination of component deformation, inelastic gasket compression and thermal cycling can transfer stress to the fasteners resulting in gradual pull out of the inserts that mount the components to panel structures in the spacecraft. Considering the strengths and weaknesses of the thermal interface materials available in the market today, predictable carbon-nanotube-based thermal gasket represents a unique solution that accelerates thermal design optimization and mission timeline while enabling significant AI&T savings.