Mechanical Reliability Analysis Of Spaceborne Remote Sensing Camera SiP

Spaceborne remote sensing camera will be subjected to vibration load,thermal load and other loads as well as the combined action of multiple loads in the working environment of outer space.These loads will affect the reliability of the internal electronic packaging structure of the camera,leading to the failure of electronic equipment and affecting the normal operation of the camera.In this paper,two SiP structures are designed,and the simulation analysis is carried out on them and the external chassis.Combined with the vibration test of the whole machine,the mechanical reliability is studied.Firstly,according to the structural design and mechanical properties requirements of spaceborne remote sensing camera,the overall design of two SiP structures is completed,and the mechanical properties of SiP structure and camera case are analyzed.Modal analysis shows that the chassis fundamental frequency is 319.44 Hz,SiP structure a fundamental frequency is364.47 Hz,SiP structure b fundamental frequency is 273.22 Hz,all greater than 100 Hz.Through static analysis,the maximum stress of the chassis is 19.223 MPa,which is far less than the yield strength of aluminum alloy is 145 MPa.The maximum stress of SiP structure a is 68.227 MPa,and that of SiP structure b is 71.713 MPa,both occurring in the corner pins near the printed circuit board,far less than the yield strength of Covent alloy 350 MPa,which meets the requirements.Random vibration analysis shows that the maximum acceleration response of the chassis is15.32 g and the amplification is 1.80 times.The maximum RMS of SiP structure a is 37.50 g,and the amplification is 4.412 times.The maximum acceleration response root mean square of SiP structure b is 46.29 g,and the amplification factor is 5.44,both of which have no obvious amplification and are within the acceptable range.Sinusoidal vibration analysis shows that the maximum acceleration response amplitude of chassis is 1.36 g,and that of SiP structure a is 0.92 g.The maximum acceleration response amplitude of SiP structure b is 1.63 g,which is small compared with the 10 g acceleration amplitude in the input condition and will not cause damage to the structure.The mechanical analysis shows that both SiP structures have good mechanical reliability.By comparing the analysis results of the two SiP structures,it is found that SiP structure a is better than SiP structure b and more reliable.Secondly,according to the test outline,a random vibration test was carried out on the whole chassis.The sinusoidal frequency sweep test curves before and after the random vibration test had a good coincidence and no obvious deviation,which met the requirements of the test outline.It showed that the stiffness of the whole chassis did not change significantly during the test.According to the random vibration test results,the maximum acceleration response root mean square of the chassis is 31.78 g,which is 3.74 times of the input condition.There is no obvious amplification and no damage to the structure.After the electrical test,the function is normal,verify the rationality of the structure design.Finally,the temperature field and thermal stress distribution of SiP structure are obtained by thermal analysis and thermal-mechanical coupling analysis of SiP structure using the chip inside SiP structure as the heat source.Compared with the simulation results without thermal stress,it is found that the existence of thermal stress will reduce the natural frequency of SiP structure,make it more resonant,and increase the stress and vibration response.The combined action of thermal vibration load will accelerate the failure of SiP structure.