Study On The Performance Of Epoxy Molding Compound For Semiconductor Devices

After years of development,electronic packaging technology have gradually matured in packaging materials and production processes.However,there are still many problems in reliability of plastic packages,such as corrosion failure,and thermal shock failure,which limits its scope of application,especially in aerospace and military fields.With the widespread use of plastic packaging technology for microelectronic devices,reliability of those devices has become one of the important research topics.In this paper,the factors affecting the performance parameters of epoxy molding compound(EMC)are analyzed by the method of experimental test and molecular dynamics.Then,the finite element method is used to simulate the stress-strain behavior of the device in highly accelerated stress test(HAST),so as to analyze the impact of EMC on the reliability of the device.The main work and results are as follows: 1.The performance parameters of glass transition temperature,storage modulus,and saturation humidity of eight plastic packaging materials including G700 A,G700L,EK5600 H,EK5600GH,EK5600 GHR,GR700,GR710,and CEL-110 HF are tested experimentally.Then the differences and connections between material performance parameters are analyzed.The results show that:(1)The glass transition temperature of EMC is generally between 115??170?.(2)EMC shows a hard glass state at room temperature and a soft rubber state at high temperature.The sharp drop point of the storage modulus of EMC appears before the glass transition temperature,and the storage modulus near the glass transition temperature decreases rapidly with 1 order of magnitude;(3)The storage modulus is greatly affected by the filler content,and the two are positively related.In other words,storage modulus increased with increasing filler content.2.Based on the molecular dynamics method,the glass transition temperature and thermal expansion coefficient of epoxy resin are predicted,and the effect of silica on the mechanical properties of epoxy resin is studied.In addition,considering the water absorption of epoxy resin,the diffusion behavior of water molecules under different temperature and humidity is simulated.It is found that:(1)At 75%,85% and 100% curing degrees,the glass transition temperatures of epoxy resin are 378 k,420k and 438 k respectively.The glass transition temperature of epoxy resin increases with the increase of curing degree.(2)Thermal expansion coefficient of the epoxy resin in rubber state is about 1 times larger than that of the glass state,and it increases with the increase of the curing degree in the glass state,but the opposite in the rubber state.(3)The mechanical properties of epoxy resin have been significantly improved after the addition of silica,and the silica content has a positive correlation with Young's modulus.(4)The diffusion rate of water molecules in the epoxy resin is accelerated due to increased temperature.3.Based on the JEDEC and GJB 7400-2011 standard,the HAST simulation test and practical detection of the TO-252 device are conducted to study the performance of EMC in practical application.The results show that:(1)In high temperature and humidity environment,the plastic packaging device produces deformation of 13?25?m,which reduces its reliability.(2)The smaller the thermal expansion coefficient of EMC,the smaller the thermal mismatch with the lead frame,so the less thermal deformation.The EMC with small thermal expansion coefficient can reduce thermal deformation of the device by 7?m.(3)Saturated humidity exhibits the same change rule as the hygroscopic deformation of the frame pin.The greater the saturated humidity,the greater the hygroscopic deformation caused by it.(4)Thermal expansion coefficient will have a large mutation near glass transition temperature.Therefore,increasing the glass transition temperature(>130?)can improve the reliability of devices in HAST.