Research On Curing Process Optimization Of Epoxy Resins Used For Electronic Packaging

Epoxy resins are widely used in the field of electronic packaging with many excellent properties.However,epoxy resins will produce volume shrinkage due to temperature change and polymerization in the curing process,and the residual stress resulted from volume shrinkage will bring about unfavorable influence on packaged products.How to evaluate the residual stress of epoxy resins and control it effectively through process design and process optimization,which is very important for the application of epoxy resins in the field of electronic packaging.Therefore,we study the temperature and strain of epoxy resins in the curing process through the combination of numerical simulation and experimental analysis,in order to optimize the curing process of two epoxy resins for electronic packaging.On the one hand,it can reduce the residual stress of resins after curing.On the other hand,it can reduce the curing time of resins and improve the production efficiency without affecting the performance of the packaged products.Firstly,many experiments including DSC,DMA,FBG,were carried out to research performance parameters of two epoxy resins(E51 and E39D),such as curing kinetics,density,thermal conductivity,glass transition temperature,elastic modulus,chemical shrinkage strain,thermal strain,etc.After that,mathematic models of these parameters in the curing process were established.Three-dimensional finite element models were established with Abaqus to simulate the temperature field,curing degree field,stress and strain field of two epoxy resins in the curing process.The user subroutines were programmed in Fortran to define the performance parameters of resins in the curing process,and sequentially coupled analysis was used to perform heat conduction analysis and stress-strain analysis successively in Abaqus.Secondly,the temperature,curing degree and curing strain curves of two epoxy resins cured in different processes were obtained by adjusting the curing temperature and curing time in the finite element models of two resins.According to the difference of temperature peak,curing degree terminal value and strain terminal value of epoxy resins cured in different processes,the curing process in room temperature of E51 resin was optimized for a curing process in medium-low temperature,and it's curing time was reduesed to 15 h from 48 h.The curing process in medium-high temperature of E39 D resin was optimized too.Its curing temperature was simplified to 90?+110? from 100?+110?+130?+90?,and the curing time was reduced to 6h from 9h,and the simulation value and experimental value of residual strain reduced 27.8% and 27.2%.Finally,through the mechanical properties tests of the resin casting,the mechanical strength values of two epoxy resins before and after process optimization were obtained.The result shows that the tensile,compressive,bending and impact strength of E51 resin after the process optimization increased 3.9%,1.5%,14.5% and 16.9% respectively.As for E39 D resin,excepting the bending strength reduced 7.3%,the tensile,compressive and impact strength increased 5.0%,1.1%,1.9% respectively.The temperature and strain of two resins in the curing process before and after the process optimization were monitored by FBG.After comparing the simulation results with the experimental results before and after the process optimization,we find that the simulation errors are all less than 20%,which proves the reliability of the curing process optimization.