We present an analysis of the cost savings and performance benefits delivered by Carbice® Space Pad, a carbon-nanotube-based thermal gasket, for spacecraft builds. We show a 62% net savings in the Integration Assembly & Test (IA&T) and Thermal cost in a typical satellite build, supported by an independent analysis performed by a large space prime. IA&T cost and schedule reductions are measured against wet install and can be delivered by using Space Pad for all satellite assembly interfaces. Carbice® Space Pad 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, 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 Space Pad 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 delivers a technology that enables satellite designers to incorporate full functionality into the system payload without the shortcoming 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. The problems with RTV are numerous. First, it has a low thermal conductivity, limiting its ability to remove heat from on board electronics. Furthermore, the 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, Carbice Space Pad represents a no-compromise solution, having the benefits of both liquid and solid without any of their downsides.