Introduction The thermal resistance of a heat sink is a convenient way of describing its performance but, unlike its electrical counterpart, the thermal resistance of a heat sink is not a constant: it changes significantly with air flow. How we "understand" heat sinks is revealed by the models we use to describe their thermal resistance. Most thermal engineers use a single-term … [Read more...]
Thermal Modeling Approaches Of GaAs Semiconductors
Introduction Predicting gallium arsenide (GaAs) semiconductor temperature is imperative since it affects the performance and reliability of the chip and the design as a whole. In many circumstances, the thermal engineer will be asked to provide expeditious and accurate answers to trade studies regarding various FET layouts and geometry, metallization schemes, and conduction … [Read more...]
Thermo-Reflectance Thermography For Submicron Temperature Measurements
The primary approach to maintaining the aggressive progress in the microelectronics industry has been to increase the density of elementary transistors and to reduce the size of their active areas. As a result, the removal of heat generated by various internal system components has become a major design challenge, further complicated by the lack of knowledge of the temperature … [Read more...]
Reliability Testing Of Thermal Greases
Introduction Thermal Interface Materials (TIMs) play a key role in the thermal management of electronic systems by providing a path of low thermal resistance between the heat generating devices and the heat spreader/sink. Typical TIM solutions include adhesives, greases, gels, phase change materials, pads, and solder alloys. Most TIMs consist of a polymer matrix, such as an … [Read more...]
Thermal Effusivity
The Technical Data column of the previous issue discussed the concept of thermal diffusivity. It makes sense to discuss in this issue a related topic: thermal effusivity. While thermal diffusivity, a, is defined as the ratio between the thermal conductivity, k, and the volumetric thermal capacity, ρcp, the effusivity, e, is related to their product, as follows: It is … [Read more...]
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