Around 1980, when I joined the Heat Transfer Group at Philips CFT, my boss threw a piece of material on my desk and asked for its thermal conductivity. It took me a week digging in literature to discover that this was no easy question to answer, despite the simple mathematics behind a steady state measurement: k=q/∆T/A, with k the thermal conductivity, q the dissipation, ∆T the … [Read more...]
editoral: why standardization is mandatory: on the incorrect use of thermal impedance in the TIM world
Clemens J.M. Lasance Editor-in-Chief, Fall 2010 Issue Some time ago I devoted my editorial to the problems caused by the veeerrryyy slow adherence to the use of SI units to which the U.S. committed itself in 1872. When talking globalization we should speak the same scientific language, and when there are conflicts of interest, logical reasoning should prevail to decide upon … [Read more...]
thermal facts and fairy tales: fully-developed channel flow: why is Nu constant?
Clemens J.M. Lasance Philips Research Laboratories Emeritus The last time the subject of my column was: ‘Most of us don’t live in wind tunnels, neither in the world of Nusselt.’ I promised more comments about the (mis)use of the heat transfer coefficient h in real-life applications where we are dealing with multiple sources, anisotropic PCBs and multilayers. In this column … [Read more...]
thermal facts and fairy tales: most of us live neither in wind tunnels nor in the world of Nusselt
Having read myriad papers/articles/books/reports on thermal management, I feel there is a lot of misunderstanding about what really should drive a sound approach of how to tackle the thermal problems that tend to land on the desk of thermal designers. I also have the feeling that many “how to” articles presented on the Web are just meant to show off the knowledge of the author … [Read more...]
LED Thermal Standardization: A Hot Topic
Introduction The main topic of the article is how to cope with the increasing need for standardization of thermal characterization of LEDs (Light Emitting Diodes) and LED-based products (see Fig.1 showing a typical LED package). The LED-business is growing much faster than analysts predicted five years ago. Unfortunately, the progress in thermal characterization has not kept … [Read more...]
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