Study On Sealing Performance Of The Electrical Connector Operating At Cryogenic Temperatures

Electrical connectors have been widely used in electronic systems for various industries, such as aerospace industry, electronic industry and communication industry. An electrical connector allows two separated electronic equipments to transfer signal and/or energy between them. For an electrical connector operating at cryogenic temperatures, the pressures, temperatures and/or even fluid media in the two spaces are generally different, which requires the electrical connector to have good sealing performance.The socket of an electrical connector, usually made of expansion alloy and sealing glass, is the key component for the sealing function of the connector. The insulator made of sealing glass keeps the contacts made of expansion alloy in their own positions to ensure the effective signal transmissions. After fabricated at room temperature, the electrical connector working at cryogenic temperatures may have the trouble of leakage, due to the different thermal expansions of the shell, the contact and the insulator materials, which may then induce the residual stress at the sealing interfaces and even cause the cracking to some extent.In order to improve the sealing performance of cryogenic electrical connector, we have conducted some related research work, which can be included to the following three aspects.1) Based on the discussion and summary of the principal of the strain gage method used to measure the characteristic parameters of the thermal expansion, an experimental setup has been built to measure the linear coefficient of thermal expansion at the temperatures from77K to293K. After the verification test and parameter correction, the setup was then used to measure the characteristic parameters of the thermal expansion of the materials related to the cryogenic electrical connector working at the temperatures from77K to293K. The measured materials include the expansion alloy such as4J29,4J33,4J34,4J29A,4J29B,4J29C and4J29D, and the sealing glass such as DM-305, DM-308and7070. The contraction-temperature curve and the mean linear coefficients of thermal expansion in different temperature ranges was presented.2) To check the possibility of leakage at different locations, the residual stress of the sealing component was simulated and analyzed with the software ANSYS. The influences of pin radius, pore radius, center distance, material combination and working temperature on the sealing performance were analyzed in details. 3) Another experimental setup has also been built to test the sealing performance of electrical connector. The cryogenic electrical connector samples were tested and all qualified through the environmental tests, where the detection scheme was designed according to the related standards at home and abroad. The decision of the structure and material of the cryogenic electrical connector referred to the result of the above simulation.