Through the technical investigation, it is found that the cause of the low-temperature data packet loss of a certain type of avionics switch is the local stress of the thermal shims originally designed. The physical properties and application range of 4 kinds of thermal interface materials, such as thermal silicon gel, thermal silicon grease, thermal glue and thermal gasket, were analyzed, and some samples were actually assembled. The test results showed that: Compared with traditional dielectric materials such as thermal conductive silicon grease, thermal conductive adhesive and thermal conductive gasket, thermal conductive silicon gel as a new thermal interface material has achieved better test results in a number of targeted tests such as high and low temperature performance test, crash safety test, continuous vibration test and so on, and can be applied to the production of avionics products.