Preparation And Performance Optimization Of Epoxy Molding Compound For Electronical Packaging

The high-speed development of modern advanced information technology requires higher reliability of semiconductor devices,and therefore requires much higher performance of electronic packaging materials.Epoxy molding compound(EMC)has been widely used as a semiconductor electronic plastic packaging material in the world.But there are some gaps in the property of low stress,low moisture absorption and reliability.Based on the low-water absorption and low-stress EMC R&D platform of Henkel Huawei Electronics Co.,Ltd,in this paper different adhesion promoters were selected to improve the performance of EMC,the thawing processes and the void issue of the packaging process were studied and optimized.Meanwhile,the defects emerged in molding process were analyzed and the corresponding solution was proposed.(1)Epoxy silane coupling agent,amino silane coupling agent,titanate coupling agent and amino imidazole were selected as adhesion promoter to prepare series of EMC to compare the effect of the adhesion promoter.And the main property index,such as gel time(GT),spiral flow length(SF),viscosity,CTE and others were tested.The study shows that amino imidazole can efficiently catalyze the reaction of epoxy resin and curing agent and reduces the SF.The four adhesion promoters all have little effect on the workability of EMC.(2)The effect of air dew point on EMC thawing process was studied.The results show that the air dew point changes significantly with the change of temperature and humidity.At the same temperature environment,the higher humidity,the higher dew point.While the environmental conditions of molding process is 30 and 60% RH,the ?air dew point is 21.3 ?;Therefore,in order to ensure sufficient thawing,our recommended thawing condition is 25 and 24 hrs.?(3)Three kinds of lead frames,such as bare Cu frame,lead-plated Ag frame and lead Ni-plated frame,were used to study the delamination of EMC at the interface of Cu,Ag and Ni.The results show that the four adhesion promoters all increase adhesion of EMC on Cu and Ag.On the bare Cu lead frame,the EMC without adding and adding the adhesion promoter both have no delamination.On the Ag-plated lead frame,amino silane coupling agent,titanate coupling agent and amino imidazole could improve adhesion significantly,and no delamination is found.On the Ni-plated lead frame,only the amino imidazole can effectively improve the adhesion of EMC to Ni and no delamination is found.(4)In the study of the voids issue of EMC encapsulation,the factors affecting void,such as compression ratio of pelletized EMC,entrained gas of raw material,generated gas of reaction,the relationship of filler rheological property and void,the relationship of silica micro-powder particle size and distribution and void,were discussed.The results show that eliminating the agglomeration of the filler nanometer powder and turning the void into nanometer dispersed micropores in each place is the fundamental solution to solve the void issue.(5)The defects generated in the EMC molding process,including the incomplete filling,air void,delamination,sticking,mold stain,flash and bleed,and so on,were analyzed in this paper.And the effective solutions were proposed.In conclusion,the basic property indexes of EMC and the adhesion between EMC and metal lead frames are improved,and the solutions of some defects are found and proposed for some customers.A new product called G5-imp ie found,which extende the application field of G5.It successfully achieves high returns for the company and lays a good foundation for the further development of the high reliability epoxy mold plastic electronic packaging materials.