With the development of infrared imaging technology, especially high resolution imaging instrument for space remote sensing, the requirement of suppressing stray light the optical system is more and more high, thus suppression of stray light of IR detector module as the core device of target detection and imaging is important. The design and processing cold shield is the key of infrared focal plane detector dewar for suppressing stray light, which mainly play a role in suppressing stray light outside of field view and improving background limited detectivity of IR detector. The structure of the cold shield is mainly effect Geometry Composing Function (GCF) of the stray radiation transmission, while Black coatings of cold shield influence bidirectional reflectance distribution function (BRDF) of stray radiation transmission. This paper mainly study suppressing stray light of cold shield with black phosphating process and black nickel plating and point source transmittance (PST) is used as the evaluation index for suppression of stray light, which can be measured accurately. A PST test system in near infrared wave band has been set up for measurement of cold shield’s PST, which coupling infrared light source with light guide tube for greatly improving the uniformity of infrared light source, while the dynamic range of test system decrease slightly. After testing and verification, light source instability is less than 1% , Non uniformity of light source at the exit of the parallel light tube is 7.4%@ 87.5mm×87.5mm.and dynamic range of test system is 0~1.5×10-5, thus the test facility can satisfy PST test of stray light. The PST curve with angle for one stage cold shield with black phosphating process and black nickel plating are measured and consistent with numerical simulation, which first decrease rapidly with increase of the angle, then slowly vary after 35 angle for the structure of one stage cold shield, the results is useful for optimizing design of infrared detector modules for control of stray light.
This paper designs a vacuum packaged Dewar for meteorological satellites. It integrates an 80 × 1 long wavelength photodetector with a wavelength of 13.2 μm to 13.8 μm and a dual band focal plane detector with a wavelength of 10.3um-11.3um / 11.5um-12.5um. The detector uses a mechanical cooler to reach an operating temperature of 60K. The theoretical calculation and simulation analysis are carried out from two aspects: cold load and mechanical vibration of Dewar. The analysis shows that when the ambient temperature is room temperature and the detector operating temperature is 60K, the total heat loads of the cold plate is 1.25W. Where the wires loss accounts for about 36% of the total heat load and the detector Joule heat accounts for about 21%. The mechanical vibration analysis of Dewar shows that the cold plate pillar is the main factor affecting the mechanical properties of the structure. Increasing the pillar support increases the base frequency of the Dewar from 379 Hz to 539 Hz, thereby increasing the mechanical base frequency of the Dewar components.
Wire bonding is one of the most widely used methods in the field of electrical connecting in packaging. The main characteristics of common wire bonding materials and process parameters affecting the reliability of wire bonding are discussed and analyzed. The evaluation method of wire bonding quality is described, and the measures to enhance the reliability of wire bonding are put forward. The results show that of all the wire materials, gold wire (Au) has the best comprehensive performance which used most widely. Aluminum wire (Al) and copper wire (Cu) are ideal materials for the replacement of Au because of low cost. Platinum wire (Pt) is mainly used in low temperature packaging for its low heat loss. In terms of bonding process parameters, bonding force is an important parameter for the shape and strength of bonding point. Adjusting the bonding force is an effective method to solve the problem of pad damage and bonding interface slip. Ultrasonic power and time are the important factors affecting bonding strength. Usually it is easier to bond wires with higher bonding temperature, and appropriate temperature is exist due to the device’s tolerance temperature. In the wire bonding quality evaluation methods, microscopic observation is the simplest method to evaluate the bonding quality. The mechanical testing methods include wire pull test and ball shear test. Environmental tests include temperature cycling, electromagnetic resonance test and other testing. It is mainly used to evaluate the overall performance and fatigue properties of wire bonding. As a result, the mechanical testing and environmental testing are the effective methods to adjust the new bonding process , and microscopic inspection is an effective method for bonding quality assurance.
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