It doesn't take long for an electronics assembler to realize that a thermal interface material (TIM) is essential when two or more solid surfaces are in the heat path. Standard machined surfaces are rough and wavy, leading to relatively few actual contact points between surfaces. The insulating air gaps created by multiple voids of "contacting" hard surfaces are simply too … [Read more...]
Calculations for Thermal Interface Materials
It's no news to any of the readers of this publication that the increased power dissipation of integrated circuits has led to continuous refinement of package designs and component materials. This trend has increased the importance of thermal interface materials (TIMs) as a key factor in determining the thermal performance of packages intended for high-power applications. This … [Read more...]
E missivity in Practical Temperature Measurements
When making temperature measurements with infrared cameras and point detectors, we are always facing the question of the emissivity of our sample. In practice we would like to have a single number set in the IR device. To approach the question, let's first recall some fundamental definitions. Planck's radiation law gives the energy density emitted by a blackbody as a function … [Read more...]
Thermal Capacitance
When time enters the equations, the ability of a material to store or release heat becomes a crucial parameter. This issue's technical data column is devoted to a basic understanding of thermal capacitance. Thermal capacity (or heat capacity) is defined as: Cth = V � � cp [J/K] where: V =Volume (m3) = Density (kg/m3) cp = Specific heat (J/kgK) at constant pressure (the … [Read more...]
Optical Measurement Of Flip-Chip Package Warpage And Its Effect On Thermal Interfaces
Warpage of FC-PBGA Packages Flip chip technology has emerged as an important chip-level package solution to meet the ever-increasing demand of high I/O requirements. The flip chip technology was implemented originally for a multi-layer ceramic substrate. In the ceramic flip chip package, a shear strain in each bump, produced by the mismatch of the coefficient of thermal … [Read more...]
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