Research On Underfill Packaging Process Of Flip-Chip Base On Surface Energy Theory

In the flip-chip packaging process,underfill is an important process.Establishing a mathematical model for predicting the underfill process has positive implications for improving the packaging process and optimizing the chip design.Existing forecasting models often need complex methods to obtain the average capillary pressure.This paper analyzes the flow process of the flip-chip underfill from the energy point of view.It is considered that the underfill process essentially is the low interface energy replace the high interface energy.During the process,the surface energy released is converted into the kinetic energy of the underfill fluid and overcome the energy loss of fluid resistance.Based on this analysis,a new analytical model of the underfill flow is established,which avoids the complicated calculation of the average capillary pressure.In order to detect the permeability of the flip-chip,a flip-chip permeability testing device was designed and manufactured based on Darcy's law.Used a visual underfill flow experiment platform to underfill experiment to verify the established analytical model of underfill flow.The main research contents and results of this paper are as follows:(1)Based on the theory of surface energy and the law of conservation of energy,a new mathematical model was established to analyze the process of underfill flow.(2)Based on the Darcy's law,a novel flip-chip permeability testing device was designed and manufactured,The accuracy of the permeability testing device was verified by comparing with the numerical analysis result of permeability.(3)The underfill flow experiment was carried out by using the visual underfill flow experiment platform.And the new model of underfill flow based on surface energy theory was verified.