Modeling And Impedance Calculation For PDN On FCBGA Package Level

As the development of the entire chip industry is pursuing the trend of high power consumption,high speed,high density and low voltage,the requirements for system performance are also getting higher and higher.In order to adapt to higher operating frequencies,the package size is getting smaller and smaller,and the package form is also more and more,and the denser interconnection structure greatly increases the influence on signal transmission.Moreover,the design and production cycle of the entire chip has become shorter and shorter.If the performance of the entire product is tested after the product design,the whole work will become very complicated.So the designer must be able to design the package at the beginning of the work.The pre-simulation analysis of the design is performed to obtain the impedance of the power distribution network,and the impedance change can be analyzed in detail from the simulated curve.Through such a pre-simulation process,the design can be adjusted and optimized to optimize system performance.So it will focus on the FCBGA package,and analyze the modeling and simulation to obtain the Power Distribution Network parameters of the power distribution network.In order to calculate the relevant parameters of the PDN of the power distribution network of the package,according to the specific structure of the package,the corresponding physical and electrical modeling will be carried out,the impedance is calculated by the corresponding algorithm,and then input through the MATLAB GUI.The form of the package parameters completes the impedance calculation for the specified package structure.The basic unit models of the FCBGA package include bump,power/ground plane,vias,and solder balls.The specific method is to model these basic unit models,and cascade the established equivalent models to obtain the PDN impedance of the entire power distribution network.For the bump,because of the small size,we directly equivalent it into the form of an inductor.According to the distribution of the power ground bump,the self-inductance and mutual inductance are calculated by the empirical formula of two straight straight wires,and then the entire impedance of the bump module is obtained.For power ground planes and vias,we model the two together because of the nesting relationship between the two in the actual structure.The specific method is: according to the size of the package stack,the most accurate and suitable modeling method is used to equilibrate it.After analysis,the PDN impedance between the calculation planes should be calculated by using the cavity algorithm,and then the port will pass.The hole is cascaded with the cavity model.The solder ball connects the package to the board,it exists in the form of bumps.And the feature size is also very small,so it is equivalent to an inductance model when modeling.And the size of its inductance can be calculated by empirical formula or fitting formula.Finally,each module is integrated through its circuit topology relationship,and the output parameters and output curves of the FCBGA power distribution network PDN can be obtained.At the same time,the integrated overall model also incorporates the effects of package capacitance and ODC capacitance,which provides designers with the appropriate value and location of the decoupling capacitors.Finally,the effect of the board level is added to obtain the comparison result of the full link.At last,the results will be based on a tool software that can quickly calculate the relevant parameters and output curves by inputting the basic package parameters.Compared with other electromagnetic simulation software,the simulation speed has been greatly improved,which greatly shortens the simulation time and provides more convenience and time for design.