Research On Low Temperature Thermal Characteristics Of Cryogenic Infrared Detector Assembly

Cryogenic infrared detectors are widely used in high end weapons because of their high sensitivity,fast response and wide range of detectors.Because of its application in the military field,there are stringent requirements for the key performance indicators of the cryogenic infrared detector assembly,such as volume,weight,cooling time,power consumption and reliability of detectors.Through the application of integrated detector Dewar cryogenic assembly,the volume,weight and power consumption can be optimized from the mechanical structure.About how to optimize the cooling time of the assembly and the reliability of the detector,it can be achieved by studying the low temperature thermal properties of the cryogenic infrared detector assembly.The low temperature thermal properties,mainly refers to heat load,cooling time and reliability of the detector package which caused by working at low temperature.The main contents of the research include the influence of various factors on cooling time,the optimization method of thermal mismatch after detector packaging and the optimization technology of thermal properties of key components.In this paper,according to the requirements of low temperature thermal properties of the cryogenic infrared detector assembly,it concerns the research aims of the present project.Through theoretical analysis,reasonable verification experiments and the optimization study of thermal properties of key components,the influence of low temperature thermal properties of the cryogenic infrared detector assembly is obtained.And the key components of the relevant thermal properties are achieved.This paper takes the 320×256 specifications cryogenic infrared detector of typical IDDCA as an example,the influence factors of cooling time are obtained by establishing thermal module and theoretical analysis.The influence of various factors on the cooling time of the assembly is obtained by the experiment of cooling time.This paper takes the typical package of 320×256 specifications of cryogenic infrared detector as an example,through ANSYS simulation analysis,it shows the stress and strain by the expansion coefficient to the detector under the certain cold platform machine size.And according to the principle of optimization stress,cold platform material was identified as invar 4J36.The experiment of strain change is carried out on silicon surface before and after packaging of the infrared detector with different substrate material.According to the experimental results,it is concluded that the detector module with the balance layer structure and the Al N ceramic substrate which calls additional strain on the detector are smaller.In this paper,the research work on the optimization of thermal properties of the key parts is carried out.Through reasonable preparation process design,radiation gilded outer surface and inner surface blackening electroforming cold shield is achieved,which has optimized radiation heat leakage.The heat load of the assembly under 80 K is reduced by about 6.6mW.Taking K508 cryocooler as object,the study on the preparation of low leakage heat and high strength integrated cold finger is developed.Integrated cold finger parts are obtained.Then coupled with the K508 cryocooler,about 610 mW cooling capacity was got under 80 K.The study on the preparation of metal matrix composites with high thermal conductivity and low expansion coefficient is developed.Using 4J32 material as matrix and 30% copper material as reinforcing phase,the metal matrix composites substrate with?21.7mm×0.6mm is obtained.Its expansion coefficient at normal temperature is 2.23×10-6K-1 and its thermal conductivity is 34.67 W/(m·K).