APPLICATION OF FDTD METHOD TO ANALYSIS OF ELECTROMAGNETIC-RADIATION FROM VLSI HEATSINK CONFIGURATIONS

The electromagnetic radiation from a VLSI chip package and heatsink st ructure is analyzed by means of the finite-difference time-domain (FDT D) technique. The dimensions of a typical configuration calls for a mu ltizone gridding scheme in the FDTD algorithm to accommodate fine grid cells in the vicinity of the heatsink and package cavity and sparse g ridding in the remainder of the computational domain. The issues perta ining to the effects of the heatsink in influencing the overall radiat ing capacity of the configuration are addressed. Analyses are facilita ted by using simplified heatsink models and by using dipole elements a s sources of electromagnetic energy to model the VLSI chip. The potent ial for enhancement of spurious emissions by the heatsink structure is illustrated. For heatsinks of typical dimensions, resonance is possib le within the low gigahertz frequency range. The exploitation of the h eatsink as an emissions shield by appropriate implementation schemes i s discussed and evaluated.