Characteristic Analysis And Optimization Of System-in-package Based On CCGA

At the beginning of the 21st century,based on the urgent need for high-density integration and high-speed packaging,system-in-package has been rapidly developed.Its biggest advantage is that it adapts to Moore’s Law,integrates independent integrated circuits and components,reduces signal delay time and volume,and having the advantages of low cost and short development period.However,SIP also has its shortcomings.At present,its reliability attracts widespread attention.This paper has completed the optimization of a new type of system-in-package structure based on CCGA.The characteristics of this structure have been systematically analyzed through the software ANSYS.After repeated optimization,the overall reliability of the structure has been improved.Those can provide a powerful reference for future SIP research and design.First,the establishment of the initial parametric geometric model of SIP structure based on the CCGA which is the research object of this paper is completed through the software PROE.The structional characteristics are analyzed by means of software ANSYS,the results are listed as follows.The natural frequency of the model are 970.48 Hz,1367.1Hz,2059.3Hz,2492.0Hz,2892.2Hz,and 3046.5Hz which are obtained after extracting the6th-order mode.The trend of temperature is consistent with the stress of the thermal coupling,and the maximum stress value is located between the substrate and FC.Mechanical shock,sinusoidal frequency sweep which load is acceleration and random vibration,the stress distribution is relatively concentrated and basically symmetrical.While the load of sinusoidal frequency sweep is displacement,stress distribution is mainly located inside the Kovar frame.The deformation and stress values of the constant acceleration are symmetrically distributed,and the minimum value of the deformation is located at the center of the cover.The cover plate is less likely to contact the internal chips and bonding wires inside the Kovar frame.Secondly,in order to complete the preliminary structure optimization of SIP based on CCGA,input factors and response values are determined for different situations,the corresponding sensitivity extraction is completed,the optimization direction was clarified,and the key factors for multi-objective optimization were determined.Then,based on the specified key factors,response values and optimization goals,the multi-objective optimization and calculation of the structure is completed.It turns out the distance between chip 5 and 6,chip 7 and 10,the height of the Kovar frame and the CCGA,the Young’s modulus of the CCGA and the Kovar frame.Based on optimized results,the model of original structure was changed and its correctness and feasibility has been verified by simulation.It is found that the stress value of mechanical shock is reduced to about 1/5 of the original,the stress value of random vibration is reduced to about 1/3,and the absolute value of the constant acceleration deformation is decreased by 0.2351 mm,etc.,so as to get a better structure.Those realized that the overall reliability of the structure was improved by the slight adjustment of geometry and material parameters.Finally,in order to obtain a more reliable structure,the thermal fatigue mechanics analysis of the CCGA of the structure is first completed.It is concluded that the distribution of equivalent stress and plastic strain are basically symmetrical,increasing from the center to the surroundings,and the maximum stress value and the maximum equivalent plastic strain value are located at the same position.The equivalent stress and equivalent plastic strain change periodically along with the thermal cycle;the inelastic strain energy density increases continuously with it.At the same time,based on input factors,response values and specified optimization goals,the optimization of the CCGA thermal fatigue life is achieved.Then,it turns out the radius of the CCGA,the height of the LTCC substrate and the thickness of the Kovar frame.In order to verify its correctness and feasibility,simulation verification and calculation are carried out.It is found that the thermal fatigue life of CCGA was increased by 2.6 times of the original.After the above optimization,a new SIP structure based on CCGA with higher reliability is finally obtained.