Introduction In recent years, high-power, high-brightness Light Emitting Diodes (LEDs) have penetrated into an ever-increasing number of lighting applications. For such devices, maintaining a low die temperature is becoming a huge challenge because of the escalating power density (e.g., 200-300 W/cm2 for the latest generation). Active cooling solutions are rarely considered as … [Read more...]
Modeling Air-Cooled Heat Sinks As Heat Exchangers
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...]
Thermal Strain in Semiconductor Packages, Part II
Introduction This Calculation Corner continues Part I, published in the previous issue [1]. Part I described the construction of a typical flip-chip package configuration for high-power chips, consisting of a laminate assembly of materials adhesively bonded together and having different Coefficients of Thermal Expansion (CTE). The process of bonding these different materials … [Read more...]
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