| Low-temperature co-fired ceramic technology has been widely used in radio frequency,communication and medical electronics after decades of research and development due to its high integration and high performance.Since the low temperature co-fired ceramic circuit board is difficult to match the thermal expansion coefficient of the package metal during packaging,the post-package annealing causes large deformation and thermal stress of the circuit board;at the same time,if the structural design of some circuit boards is unreasonable,and large thermal stress is also generated in the thermal environment,which may causes cracks on the circuit board,resulting in loss of function of the circuit board and serious damage.Therefore,thermal fault investigation,structural optimization and thermal test analysis of low temperature co-fired ceramic circuit boards have become urgent tasks.In this paper,the finite element software is used to analyze the thermal response of low temperature co-fired ceramic circuit boards in thermal environment,by comparing with the experimental measurement results to ensure the effectiveness of the thermal simulation analysis,the effects of different installation conditions on the surface deformation and stress strain of the circuit board are studied,furthermore,the selection principle of the mounting board of the circuit board and related electronic products is summarized,which provides a reference for the related electronic products to reduce the stress in the harsh environment.(1)Explain the related theories of thermodynamics and study the thermal analysis technology based on finite element method.The thermal stress calculation examples of different material laminates are used to compare and verify the theoretical analytical solutions and thermal simulation results,which provide relevant technical basis for the subsequent analysis of surface thermal deformation and stress strain of circuit board components.(2)The finite element model establishment method of low temperature co-fired ceramic circuit board assembly is studied,and the finite element thermal simulation analysis is carried out on the model.The surface deformation and strain simulation results of the board under three installation conditions are obtained.Based on the low-temperature co-fired ceramics process,combined with the simplified principle of the model,the geometrical models of the components under three different installation conditions are established.The finite element pretreatment method of low temperature co-fired ceramic circuit board assembly is studied,and the finite element model of low temperature co-fired ceramic circuit board assembly is established.The surface deformation and strain results of the board under three installation conditions are obtained by finite element simulation,which lays a foundation for the comparison between simulation and experimental measurement results.(3)The thermal test method of low temperature co-fired ceramic circuit board assembly based on digital image measurement is studied.Explain the composition of the digital image correlation system and study its measurement principle and usage.The test measurement conditions and test procedures are described.Finally,the thermal deformation and strain on the surface of the low temperature co-fired ceramic circuit board with three installation conditions high and low temperature environment are obtained.A calculation method for the surface displacement and strain measurement data of the board is proposed,and the actual measured displacement and strain on the surface of the board after interferences are obtained.(4)The effects of different installation conditions on the displacement,strain and stress of the surface of low temperature co-fired ceramic circuit board assemblies are studied.By comparing the simulation and experimental measurement results under the same installation conditions,the conclusions that the simulation process are effective and the reliable simulation results are obtained.On this basis,the simulation results of the board under different installation conditions are compared,and the surface displacement and stress-strain changes of the board are summarized.The selection principle of selecting two installation conditions,including the installation of the bottom plate and the selection of the material with the thermal expansion coefficient of the research object as the mounting base is proposed. |
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