Thermal characterization of high-density interconnects: A methodolgy tested on a model coupon

The high-density interconnection substrate invariably poses enormous difficulty to thermal design analysts due to complex metal layout patterns embedded in the dielectric matrix. A modeling method is proposed, which produces effective thermal conductivity values for elements of the substrate under a specified boundary condition. A novel parameter, the indexed metal volume fraction, is employed to highlight the importance of contiguous metal elements in providing highly effective heat conduction paths. Also taken into account is the thermal coupling between metal elements through dielectric interstices. A model PCB that has a reasonable level of structural complexity is employed to validate the present modeling method. The benchmark is provided by the numerical analysis that is performed on the model without sacrificing any structural details. The prediction by the present method and the benchmark agree within a reasonable range, while the traditional method of estimating effective conductivities grossly under-predicts the temperature.