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...]
Glass: A Group Of Familiar Materials With Varying Properties
The knowledge to manufacture glass products is already 4500 - 5000 years old, and glass in its different compounds is one of the most commonly used man-made materials. The material technical definition of glass is loose, but, typically, inorganic products manufactured by fusing and then solidifying without crystallizing can be categorized as glasses. In the electronics industry … [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...]
Pyrolytic graphite – thermal performance by structure
Continuing our discussion of different forms of carbon, this column addresses the topic of pyrolytic graphite, a material that opens up many interesting applications not only for cooling but also for scientific measurement equipment. Pyrolytic graphite - the finest forms of which are often called Highly Ordered Pyrolytic Graphite (HOPG) - is manufactured through a pyrolysis … [Read more...]
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