The electromagnetic effect of cooling fins

The electromagnetic effect of cooling fins is studied by solving Maxwell equations numerically using a FDTD method under high-frequency operating conditions. The fin is attached to a square IC chip to form a package. The overall size of the package is 25 mm x 25 mm x 17.5 mm. A smooth compact pulse with a reference frequency of either 1 or 2.5 GHz is used as the excitation source of EM waves. Six fin configurations are investigated. Computational results indicate that a fin can act as an antenna. For the present type of excitation source, resonance could occur roughly at frequencies of 2.5, 5 and 7.5 GHz. depending on the source reference frequency and fin geometries. Thus, fin effects should be considered in the electrical design phase since noises could be induced in the circuit due to the presence of fins. Copyright (C) 2006 John Wiley & Sons, Ltd.