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...]
Modeling Heat Conduction in Printed Circuit Boards Using Finite Element Analysis
Introduction Heat transfer in and around a printed circuit board (PCB) is generally very complex. Some of the heat generated in components is conducted away through the multiple conducting (trace) layers, vias, and dielectric layers of the board; and some is dissipated by convection and radiation from the exposed surfaces. There has long been a focus on characterizing the … [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...]
The Temperature Ratings Of Electronic Parts
Introduction Semiconductor parts are most often specified for use in the "commercial" 0 to 70°C and, to a lesser extent, in the "industrial" -40 to 85°C operating temperature range. These operating temperature ratings generally satisfy the demands of the dominant semiconductor customers in the computer, telecommunications, and consumer electronic industries. There is also a … [Read more...]
Thermal Interface Materials: A Brief Review of Design Characteristics and Materials
Introduction In the past few decades, as microprocessors have continued to evolve along Moore's law, providing increased functionality and performance, there has been an associated increase in cooling demand driven both by the increase in raw power and in local power densities on the die, commonly referred to as "hot spots"[1, 2]. Considerable attention has therefore been given … [Read more...]
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