Thermal effects in a printed circuit board due to heat emission from mounted components

An assembled printed circuit board has a number of components mounted on it. The components may be active or passive, high power or low power, but all of them produce heat during operation. During operation, heat is transferred from and to the PCB track by conduction through component leads, between components through air by convection or simply by radiation without any medium. In this paper the heat transfer mechanisms between the components in a PCB by all the modes of heat transfer is analyzed. The mathematical model to determine the heat flow and temperature as a result of heat transfer by conduction, convection and radiation has been developed. This type of thermal analysis helps a designer to estimate the temperatures on the board and suitably relocate components/design cooling solutions to keep the board temperature within limits. Although thermal analysis tools and software exist for a designer to use, this paper describes an empirical method to estimate heat transfer by the fundamental modes of heat transfer which can be used by the electronic designer, for analytical purposes, as an additional tool for heat transfer calculations.