Research On The Mechanism Of Coupling Deformation Of IC Plastic Package Process Based On Viscoelasticity

In the IC chip packaging molding process,due to the Thermal-Fluid-Solid coupling effect between filling melt flow and the IC chip,the chip will produce coupling deformation,which will seriously affect the performance of IC chips.However,how to accurately predict and precisely control IC chip's Thermal-Fluid-Solid coupling deformation is still a problem to be solved urgently in IC chip packaging molding.At present,the existing theory of Thermal-Fluid-Solid coupling deformation prediction based on pure viscous Newtonian fluid is difficult to accurately describe the mechanism of Thermal-Fluid-Solid coupling of IC chip.In this paper,the theoretical model truly describing the formating mechanism of viscoelastic Thermal-Fluid-Solid coupling deformation in the IC chip packaging molding process was established,which was particularly important for prediction and precisely control the Thermal-Fluid-Solid coupling deformation of IC chip.And so far this scientific problem has not yet been resolved,for which theoretical research of this scientific problem was carried out in this paper,and the virtual simulation technology of the viscoelastic Thermal-Fluid-Solid coupling deformation in the IC chip packaging molding process was established.The relationship between viscoelastic Thermal-Fluid-Solid coupling deformation with viscoelastic rheological properties and process parameters was constructed,and the formating mechanism of viscoelastic Thermal-Fluid-Solid coupling deformation was revealed,and finally implement the leap transformation of the IC chip packaging molding technology from recent groping manufacturing in which one success was searched in many accidental opportunities to seeking to the whole process integrated control industrialized and scientific manufacturing in which quality was guaranteed by science and success was guaranteed by technology.The comparative analysis results of viscoelasticity melt IC plastic package molding process and pure viscous melt IC plastic package molding process show that there is an obvious essential distinction between the Thermal-Fluid-Solid coupling effect of viscoelastic melt and the Thermal-Fluid-Solid coupling effect of pure.Research on the Thermal-Fluid-Solid coupling mechanism between viscoelastic melt and IC chip and exploration on the deformation mechanism of IC chip under multi-field(Thermal-Fluid-Solid coupling pressure field,temperature field and stress field)cooperative coupling effect are the theoretical prerequisite for accuratly prediction of IC chip Thermal-Fluid-Solid coupling deformation and research the precisely control technology of Thermal-Fluid-Solid coupling deformation of the IC chip.Based on the PTT viscoelastic constitutive model,theoretical model accurately describing the viscoelastic Thermal-Fluid-Solid coupling effect and multi-field cooperative coupling deformation of IC chip between viscoelastic melt filling flow and IC chip during IC plastic package process was established.And the virtual simulation technology of the viscoelastic Thermal-Fluid-Solid coupling deformation in the IC chip packaging molding process was established,which provides theoretical support for revealing the deformation mechanism of IC chip in polymer viscoelastic melt filling environment.The relationship between viscoelastic Thermal-Fluid-Solid coupling with viscoelastic rheological properties and process parameters was studied.The Thermal-Fluid-Solid coupling deformation of IC chip will increase with the increasing of reference melt viscosity,viscosity ratio and injection velocity,and decrease with the increasing of melt relaxation time and mold wall temperature.The research found that the essential influence of polymer melt viscoelastic properties on the formation of Thermal-Fluid-Solid coupling deformation are reducing of Thermal-Fluid-Solid coupling pressure difference between chip up and down surface,and possessing of polymer melt filling flow viscoelastic normal stress which has elasticity support constraints effect of the chip Thermal-Fluid-Solid coupling deformation,which leads to the Thermal-Fluid-Solid coupling deformation of the IC chip induced by the viscoelastic melt filling flow is obviously smaller than that induced by the pure visco Newtonian melt.The research found that the key control parameters of the Thermal-Fluid-Solid coupling deformation between viscoelastic melt and IC chip are the Thermal-Fluid-Solid coupling pressure difference between the upper and lower surfaces of IC chip.The inhomogeneous temprature field induced by the conjugate heat transfer between viscoelastic melts and IC chip plays a promoted role in the formation of the deformation of IC chip,and the promoting effect is enhanced with the increase of melt filling time.The flow normal stress field of viscoelastic melt plays an inhibitory effect on the formation of the Thermal-Fluid-Solid coupling deformation of IC chip,and the inhibitory effect will decreases with the increasing of melt filling time.