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...]
Trends in Cooling of Electronics: The Use of Thermal Roadmaps
Introduction Miniaturization, integration of functionality, and the increase of clock speed are recognized business drivers in the electronics industry today. Consequences are the fast increase in power dissipation leading to higher heat fluxes, higher temperatures and larger temperature gradients. Handling these effects makes it more difficult to stay cost competitive, because … [Read more...]
Nostradamitech
The big electronics design show was in town. Gino suggested we blow off work for the day and check it out. I was a little short on promotional pens and key chains, so I fell in with him. Gino is OK, even if he's one of those Reliability Engineers. The cavernous convention center was packed with flashy booths of the usual component, CAD-tool and test equipment vendors. It's … [Read more...]
Simple Formulas for Estimating Thermal Spreading Resistance
A problem commonly encountered in the thermal analysis of electronic packages is that of thermal spreading resistance. Thermal spreading resistance occurs as heat flows by conduction between a source and a sink with different cross-sectional areas. Examples of two situations involving spreading heat flow are shown in Figure 1. One example is that of a chip mounted on the bottom … [Read more...]
Surface Flatness
Surface flatness is an important issue for thermal designers as it is directly related to thermal contact resistance between surfaces. In this column, the definitions of surface flatness related parameters are discussed. These definitions are presented here as in the ASME B46.1-1995 standard [1]. Surfaces are characterized by three main parameters: roughness, waviness, and … [Read more...]
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