Introduction Since their introduction, multilayer printed circuit boards have provided a significant benefit to the thermal management of IC packages. As is widely recognized, the power and ground planes in these boards function as fins and spread the heat beyond the package footprint and enhance heat transfer to the air. Heat can flow into these planes by conduction either … [Read more...]
Thermal Vias – A Packaging Engineer's Best Friend
Introduction In the 1990's, with the advent of surface mounting of semiconductor packages, multilayer printed circuit boards and multilayer substrates for Ball Grid Array packages were introduced. In order to create electrical interconnections between the different metal layers, vias are fabricated [1]. In most cases vias are hollow cylinders of copper, created by plating a … [Read more...]
Convection and radiation heat loss from a printed circuit board
In last issue's column, a method for calculating the thermal conductivity of a printed circuit board (PCB) was described. Now, we look at a more complicated heat transfer process, namely the loss of heat from the surface of a PCB to the ambient air. This situation is more challenging to describe mathematically since it involves the simultaneous processes of heat spreading by … [Read more...]
One-dimensional heat flow
The simplest heat flow situation is that described as “one-dimensional heat flow”. The Figure illustrates a one-dimensional heat flow situation. It shows heat flowing in one face of an object and out the opposite face. Each face is at a uniform temperature. There is no heat flow out of the sides of the object. The cross- sectional area of the object in the direction of heat … [Read more...]
