计算多芯片多基片模块稳态热场的层次模型

Multilevel Model of Steady Thermal Simulation for Module Having Multichip and Multisubstrate\+*

提出的层次模型将包括多芯片多基片模块的复杂热场模拟 ,分解为有确定耦合关系的形状简单的层次单元的热场计算 ,通过迭代将分区计算结果连成模块的热场 .在计算一个层次单元 (芯片、基片或底座 )的热场时 ,将其所在的层次单元 (母层次单元 )的上表面温度 ,作为该层次单元下表面的边界条件 ,而把它上表面上的层次单元 (子层次单元 )的下表面的向下热流作为置于它上表面的等效热源 .通过芯片→基片→底座→基片→芯片→基片…的几轮迭代就可收敛到正确值 .提出的层次单元间的耦合强度 (即每轮计算中 ,母层次单元上表面的温度改变不是全部 ,而是部分用于更新其子层次单元的下表面的边界条件 )保证了所有情况下的迭代收敛 .层次模型算法不仅速度数量级地高于普通的模块一体计算 ,而且热场与产生它的热源关系清楚 ,便于指导模块设计 .计算与测量在实验误差 ( 5℃ )

A novel multilevel model of steady thermal simulation for a module having multichip and multisubstrate,and some of chips may be directly on the heatsink,is proposed.This model changes the complex module thermal simulation into interaction of much simpler thermal calculation of the structure units (chips,substrates,and the heatsink) of the module.When a thermal field of a unit,for example a substrate,is calculated,the top surface temperature of the heatsink is considered as the bottom boundary condition of the substrate,the bottom downwards heat flux of chips topped on the substrate is considered as the equivalent heat source at the top surface of the substrate.The thermal field of chips and the heatsink is calculated in the similar way.After few iterations the module thermal field converges to its solution.The avoid divergence the change of the temperature at the top surface of the unit at lower level (a substrate or the heatsink) is partially not entirely used to modify the bottom boundary condition of relevant units (chips or substrates) at higher level.This model is not only fast, but also gives clear link between the thermal field and the heatsources.It can simulate any module even it has other modules placed on its top surface.The simulated results agree with measurement results within the experimental error(~5℃).