| The microwave components of aerospace and other major equipment will be affected by environmental loads and cause failure during service.50%of the failure are caused by temperature loads and 20%are caused by vibration loads.The failures mostly occur in the position of interconnect solder joints of microwave component packaging.The ceramic ball grid array package(CBGA package)is currently used in microwave components to realize the package interconnection of chips and control components because of its high density and high airtightness.In addition,since the solder joints in the CBGA package play an important role in mechanical connection,electrical conduction and signal transmission in the microwave component the reliability of solder joints directly determines the reliability of microwave components.With the development of aerospace electronic equipment in the direction of high performance and high reliability;at the same time,the traditional empirical design method of microwave components(design-processing-experiment-adjustment)has the disadvantages of high R&D cost and long cycle,which puts forward higher requirements for the design cycle and service reliability of microwave components In response to the above problems,this article takes a certain aircraft microwave component CBGA solder joint as the research object.In order to improve the reliability of the microwave component and shorten the development cycle during the research and development stage,temperature cycling and random vibration load of the microwave component CBGA solder joint geometry,layout and other characteristic parameters Optimized design are carried out,the specific research content is as follows:(1)Calculate the reliability of CBGA solder joints under temperature and vibration load based on the structural reliability theory.Using the finite element simulation software ANSYS,the initial value model of the microwave component CBGA package was analyzed for the structural analysis and the mechanical response analysis of the solder joint under the thermal vibration load.It was found that the maximum solder joint stress was at the joint between the solder joint of the array corner area and the substrate or PCB.The reliability of CBGA solder joints under temperature and vibration load was calculated by extracting the stress value of solder joints and combining structural reliability theory.The above research lays the foundation for the optimization of characteristic parameters such as solder joint geometry and layout.(2)Based on response surface method and genetic algorithm to optimize the geometric characteristic parameters of CBGA solder joints of microwave components under thermal vibration load.First,according to the structural reliability theory and engineering experience discussion,the influence of the thickness,the maximum radial diameter of the solder ball and the thickness of the pad on the stress,strain and reliability of the solder joint under the thermal vibration load condition is studied based on the controlled variable method.It was found that within the threshold range of CBGA solder joint geometric characteristic parameters,the solder ball height,the maximum radial diameter of the solder ball,and the pad thickness should be selected as the middle value,the smaller value and the middle value in the parameter range respectively,which will make the solder joint more reliable;Furthermore,the response surface method and multiple quadratic regression are used to construct a multiple regression model of solder joint geometric parameters and stress strain under thermal vibration load,and the value of the model determination coefficient R~2 was caculated,as well as the error of the calculated value and the simulated value to verify the accuracy of the regression model Finally,based on the regression model,a mathematical model for the optimization of solder joint geometric parameters is constructed,combined with genetic algorithm to obtain the optimal geometric parameter combination of the solder joint,and the optimal geometric parameter model of the solder joint is simulated and the reliability of the solder joint is calculated.Based on the above research methods,the initial value model of the solder joints of the microwave component CBGA package was optimized to obtain the optimal geometric parameters of the CBGA solder joints,and the structure of the optimal geometric parameter model of the CBGA solder joints was analyzed,furthermore,the reliability of the CBGA solder joints was caculated.Comparing the results of the initial value model,it is found that after the optimization of the geometric parameters of the solder joint,the stress of the solder joint is reduced by 8%,and the reliability of the solder joint is increased by 7%.(3)Based on the topology optimization method,the design of the characteristic parameters of the CBGA solder joint layout of the microwave component under the thermal vibration load was optimized.Firstly,a topology optimization method for component-level packaging solder joints is proposed.This method is based on topology optimization,and is a research method for solder joint layout optimization for component-level packaging solder joints,with reliability and design requirements as constraints.The typical BGA solder joints are summarized Peripheral type and staggered type reduce the number of solder balls by30%～50%compared with full array type.Based on the above methods and conclusions,combined with the initial simulation results of CBGA solder joints,for the 1/4 model of the microwave component CBGA package with a 10×12 full array(one solder joint is missing in the corner area),the solder joints are under thermal vibration load through the ANSYS topology optimization module Save 10%,20,25%,30%and 20%,30%,40%,and 50%of materials,respectively.The solder joint layout optimization was performed.Based on topology optimization results and combined with actual design requirements,a new solder joint layout model is implemented.Under the simulation analysis and reliability calculation,the optimal layout was selected as the optimal layout with 25%of solder joint materials under temperature cyclic load;and the optimal layout with 40%of solder joint materials under random vibration load was selected.(4)Developed a software platform for optimizing design parameters of solder joints of microwave component CBGA package under thermal vibration load.In order to enable the microwave component designers to use the method in this paper to quickly optimize the design of the characteristic parameters of the CBGA solder joints of the microwave components.The C++Builder software development tool was used to develop the software platform for the optimization design of the CBGA solder joint characteristic parameters of the microwave components under the thermal vibration.The platform can realize the simulation analysis,reliability calculation,geometric parameters and layout optimization design of the CBGA solder joints of microwave components under the temperature cycle load and random vibration load.Finally,the CBGA solder joints of the antenna microwave components of a large transport aircraft are taken as an example to verify the effectiveness and practicability of the optimized design platform. |
PDF Full Text Request