The influence of a plate-type heat sink on the interference between adjacent printed circuit boards: The case of capacitive coupling

Increases in the power density per unit volume of an IC due to higher densi ty of integration and higher operating speed cause increased heat generatio n. In order to avoid undesirable effects of the temperature increase on the reliability of the devices, heat sinks are installed. However, although mu ch research has been carried out on the cooling effect of heat sinks, littl e is known about their electrical effects. Usually, it is considered that a metallic heat sink influences the surrounding electric and magnetic fields . In this paper, the effect of the heat sink on the interference between pr inted circuit boards is studied. The adjacent printed circuit board as the noise source is considered as an electric field noise source, while the rec eived noise is considered as an induced noise on the lead wire connected to the IC terminal. In this way, the effect of the capacitance between the no ise source, heat sink, and device on the noise induced in the device is mod eled and the model is experimentally verified. The induced noise voltage on the device computed from the capacitance between the noise source and the heat sink derived from this model and the finite element method is found to agree well with the measured results at frequencies below 90 MHz. (C) 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(2): 37-46, 2001.