Application of Thermal Territories for Air-Cooled Circuit Board Design

Abstract

Multilayer glass epoxy circuit boards are good thermal conductors and can, for air-cooled devices, serve as heat sinks of considerable capacity. The best use of this property is achieved when the components on a circuit board are placed so that they have a conveniently sized “free” circuit board surface in all directions. A simple way to ensure this is to associate a virtual cooling area, here called a thermal territory, with each component. Although thermal territories are primarily intended for layout purposes, they are also very useful on the individual component level, particularly in the early stages of the design process. Experiences have shown that it is possible to avoid many mistakes if thermal territory estimates are made as soon as approximate data is available. Application experiences and calculation methods are discussed, and some rules of thumb are given.