Study On Assembly Of Near-room Temperature Focal Plane Detectors

Focal plane detectors are the core components of imaging systems.And they are the eyes of the imaging systems to detect,identify and analyze the objects'.So,they have a wide range of applications in military,industry,transportation,security monitoring,meteorology and medicine.Driven by the demands of aerospace engineering and space exploration,infrared imaging detector technology is developing in the direction of large scale and multi-band.Size will directly affect the resolution of the image.Due to factors such as material,detector process and chip yield,the scale of infrared focal arrays cannot meet the continuous growing needs of infrared remote sensing.Multi-chip or multiple focal plane modules asjustment have become the approach of technical realization and the development of trend in large arrays.Multi-band integration can avoid external interference effectively and obtain much richer,more accurate and more reliable information of target.They are widely used for space remote sensing and have important significance and value in application.In this paper,according to the requirements of large scale and multi-band FPAs and the current development status,as well as the characteristics of focal plane arrays,the design and process of integrated multi-band and multi-chip with thermoelectric coolers was studied by packaging method of multi-chip and multi-band.Multi-chip or modular splicing,quantificational spectrum control of dual-band integrated on one chip and large cold plate with thermoelectric cooler was deeply studied.There are several innovative results in the following aspects:1)Innovative online detection with high-precision laser imager,three-point support type adjustment method with piezoelectric ceramic to achieve high-precision adjustment of multi-chip or multiple focal plane modules,and a filling glue method to achieve the fixation process of the focal plane module,The three-dimensional accuracy of the spliced focal plane module is controlled at: X-axis ±8?m,Y-axis±8?m,Z-axis ±8?m(including the inherent flatness of the focal plane of ±5?m).The flatness at 220 K temperature is consistent with the flatness at room temperature.2)Multi-band integrated components were studied.In the structure,the strong reflective area of metal on the chip was optically shielded and the bands were mechanically isolated for the first time.The adjacent bands were physically isolated and blackened.The spectral crosstalk between adjacent bands reduces from 8% to less than 4%,and the outside response spectrum of adjacent bands degrades from 3.2% to 0.18%,and from 6.5% to 0.78% separately.By applying anti-reflection treatment to the high reflection area next to the photosensitive cell and blackening the filter joints,the abnormal response peaks of the adjacent bands in the small light spot test are reduced from 30% and 13.8% respectively.It is negligible.3)The large cold surface technology integrated thermoelectric cooler is studied,the heat load estimation and thermal stress analysis of the integrated thermoelectric cooler are given,and the porosity and cold surface temperature realization of several thermoelectric cooler installation methods are tested.For heat transfer,the technology of a single thermoelectric cooler and multiple thermoelectric coolers is used to realize the heat transfer and the temperature uniformity of the cold surface of the integrated thermoelectric cooler within ±0.4?.4)The module splicing technology with built-in high-power thermoelectric cooler is studied.After three-point support type adjustment,a flexible high-thermal-conductivity transmission method is used to achieve stable heat transmission at a power of 70 W.The actual test curve is in good agreement with the theoretical curve.The theoretically calculated thermal resistance value is 0.225°C/W,and the measured thermal resistance value of the fitted curve is 0.234°C/W,the error is about 3.8%.5)The developed integrated multi-band and multi-focal plane module splicing assembly,by adding a beam blocking middle aperture at the upper surface of the filters,the abnormal response peaks of signals in adjacent bands in the small light spot test are changed from 2% and 1.4% respectively to 0.And the non-uniformity of signal response is reduced to 50% by improving the surface treatment process of important surfaces,which greatly improves the non-uniformity.The structure and assembly developed have passed the reliability test,laying the foundation for product practicality and product maturity,and has reliable engineering application value.