Thermal test dies are among the major tools used in package thermal design qualification. They are usually simple chips, containing heaters and temperature sensors. The sensors measure the temperature on the chip surface as a result of the steady state powering or the time dependence of the temperature increase or decrease in case of transient qualification. From these data, … [Read more...]
The thermal conductivity of fluids
About 10-15 years ago, fluids, either directly (mainly Fluorocarbons), or indirectly (cold plates flushed with water) cooled the majority of mainframe computers. Nowadays, the expected increase in heat flux density causes a renewed interest in either passive or active liquid cooling, because the limits of air cooling come within reach. Other practical applications in which … [Read more...]
Determining the junction temperature in a semiconductor package, part IV – localized heat generation on the die
In the standard thermal test environment, thermal test chips are designed to dissipate the applied power uniformly over most of the die surface. However, in many situations of practical interest, the power is dissipated over a localized area of the die. This column provides calculation methods to deal with the latter situation. Figure 1 illustrates the situation of interest … [Read more...]
High accuracy thermal interface resistance measurement using a transient method
Heat dissipation of active devices has become one of the limiting factors in further miniaturization. While component manufacturers succeed in decreasing the overall thermal resistance of their packages, the thermal interface resistance to the board becomes the next limiting factor. Therefore, understanding interface and contact resistances becomes increasingly important for … [Read more...]
A system level cooling solution for cellular phone applications
Improving thermal performance of electronic components is very challenging due to the increasing power density and decreasing module sizes. The design trade off between electrical and mechanical characteristics and the cost of manufacturing MCM products requires innovative solutions to improve device thermal performance. The primary cooling path in portable electronics serves … [Read more...]
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