Thermal And Mechanical Analysis Of Multilayer Printed Circuit Board Assembly Structure

The printed circuit board (PCB) is composed of several materials, such assolder resist material, metallic material, as well as some of the resin compositematerial (FR-4). During the PCB’s manufacturing process, the difference incoefficient of thermal expansion (CTE) of the various materials is likely to lead thewarpage of the PCB, which reduces the safety and stability of the work of thepackaging system.The numerical simulation technique plays an important role for PCB’s design.In this thesis, the finite element method (FEM) is used to analyze the mechanicalproperties of the PCB structures in the cases of various design parameters undervariation of the manufacturing temperatures and different constraint conditions.The computed results are discussed about the influences on the PCB’s warpage dueto the choices of thickness of the substrate, modulus of elasticity of the FR-4, andthe thermal expansion coefficient of the solder resist material. Based on thecomparison and discussion, some beneficial suggestions are given on the choice ofthe design parameters of the PCB.The chip layout has an important influence on the stress distribution,displacement and temperature field of the PCB. In the present thesis, the influenceof the chip layout on the temperature distribution of the PCB has been discussed byanalyzing the temperature field under two different chip layout programs. At thesame time, the influence of the convective heat transfer coefficient on the PCB’stemperature field has also been studied by changing the convective heat transfercoefficient in the models. In addition, this thesis has analyzed the distribution ofthe warpage and stress of the PCB in the reflow process to discuss the influence ofthe chip layout on the PCB’s stress and displacement field.The proposed mechanical model and computational strategy can be beneficialfor the choice of the design parameters and the control of the warpage as well asstress peak values of the PCB structure. Moreover, the analytical resultshave some reference value for reasonable chip layout on the PCB.