Silicon sensor based particle detectors operated in a hadronic radiation environment need to be cooled to counteract the radiation induced leakage current and to prevent thermal runaway. To achieve this most efficiently, a low thermal resistance is required between the detector modules and the cooling structures. In many cases dry thermal contacts are sufficient, but especially for a large-area contact so-called thermal interface materials (TIM), largely availably on the market in many forms, are the preferred choice. However, in the use case for detector cooling there can be many requirements, such as non-liquid phase, no heat cure, low thermal impedance, no compression force, radiation hardness, making it challenging to find a suitable TIM. One option are room temperature curing two component thermal gap fillers.
The thermal test setup determines the thermal conductivity of a test sample by measuring the temperature gradient with a controlled amount of heat flow through a sample.
Mechanical tests are required to qualify the structural integrity of the thermal interface under thermal stress and mechanical stress.
Resembling the style of an ISO 4587 lap shear test, and an ISO 25217 mode-1 fracture test, test samples were prepared with a large 5 $\times$ 5 cm$^2$ adhesion overlap using plasma cleaned carbon fibre plates to have a surface comparable to its intended use case.
After testing of unirradiated samples, they have been irradiated to 600 kGy. The measured mechanical and thermal properties are presented and the results before and after irradiation are compared.