Thermal design of heat spreader and analysis of thermal interface materials (TIM) for multi-chip package

Industry demand for high power multi-chip packages is increasing to realize multifunctional compact systems. In line with industry requirements a multi-chip package suitable for high performance devices is developed. The package has 1296 I/Os. It is capable of handling 2 GHz signal speed and dissipating 75 W power with an external thermal solution. A concurrent design approach is adopted for the package design. Electrical, thermal, structural issues and assembly, and materials limitations are considered in developing this package. Package level thermal design challenges involve optimization of package structure and selection of stable thermal interface material. As a part of this project, a simulation model of the package along with the external thermal solution is developed and validated by measurements. The optimized heat spreader has been designed by performing a parametric study with the validated model. The type of thermal interface material (TIM) suitable to the package has also been identified by measurements. Desired thermal performance of the package has been achieved through design optimization of the package and selection of suitable TIM. Thermal modeling and measurement methodologies, validation and parametric study results are presented in the paper. Analysis of TIMs and measured thermal performance results of packages assembled with different type of TIMs are also discussed in the paper.