EMI Radiation Modeling And Optimization Design In Package

With the increasing of operating frequency and interation density,the EMI problem of electric products is increasly serious.Package as the bridge between PCB and Die,has been widely concerned and studied by electronic design and manufacturers.In this paper,the EMI problem of WB-BGA package and FC package are investigated.The methods to suppress the EMI radiation problem are proposed from the perspective of new route,new interconnection structure and new material in package.Furthermore,the EMI problem and thermal problems are analyzed and optimized.Based on the practical WB-BGA package,this paper shows the effect of the package lid/heatsink and WB on EMI problem.Although the cost is very low,the parasitic effects of WB is inescapable at high frequency.The ribbon wire and coaxial structure could optimize the signal transmission and radiation of WB.The attenuation can achieve 10 dB in the entire analyzed frequency by ribbon wire.To make up the shortfall of shorting vias,the resistive vias can obtain the 7 dB radiation suppression at low and high frequency.In order to protect the die and provide a better heat dissipation,the lid is usually mounted above the substrate.However,the noise from IC easily couple to the lid,which cause the resonance between lid and substrate.The radiation could be detrriorated significantly at the resonant frequency.The resistive lid can be used to mitigate the cavity resonance.When the resistance varies from 200 ?/sq to 600 ?/sq,the radiation suppression obtain maximum which is approximately 10 dB.The absorbing material can be placed on the bottom surface of lid to suppress the cavity resonance.The radiation suppression achieves nearly 8 dB.Due to the high integration density,thermal performance and EMI problem are high-profile.To solve the problem,the combination ring absorbing material and flat graphite material is proposed in this work.The proposed method can obtain radiation suppression 10 dB and temperature reduction 20 ? when the graphite varies among 20?45 mm.The research can provide application guidance for the practical product design.In addition,based on the practical FC structure,the paper explores the EMI problem of FC.The effect of grounding vias,grounding bumps,edge vias on radiation is investigated.The signal transmission and radiation can be obviously optimized by using the coaxial structure of FC package.Moreover,the radiation is investigated when the the differential traces are placed on the different metal layers and put forward route design to avoid strong radiation.