The value of thermal conductivity for most gases and vapors range between 0.01 and 0.03 W/mK at room temperature. Notable exceptions are Helium (0.15) and Hydrogen (0.18). The most common theoretical explanation of heat conduction in gases is provided by the kinetic gas theory, which treats the collisions between the atoms or molecules as the prime mode of transfer of … [Read more...]
Thermal testing and control by means of built-in temperature sensors
Introduction This paper will discuss a new approach to the measurement of the thermal properties of PCBs and the packages mounted to them. It is intended to replace traditional solutions, such as using thermocouples and data acquisition equipment. The basic idea of this approach is that the IC chips themselves will be used to measure and acquire temperature data. It will be … [Read more...]
Thermal management of handheld telecommunication products
Introduction Recent advances in mobile communications have enabled large scale development of handheld telecommunication products. Such products include cellular phones, pagers, two-way radios, personal digital assistants (PDAs), and other wireless and wireline equipment. The technological enhancements at device, package, and system levels have resulted in increased … [Read more...]
Conduction heat transfer in a printed circuit board
In this issue, we examine heat flow in a printed circuit board (PCB), which typically is a layered composite consisting of copper foil and a glass-reinforced polymer (FR-4). A cross-sectional view of such a laminated structure is illustrated in Figure 1. The Figure indicates the numbering system that will be used for indicating the different layers, numbered 1 through to … [Read more...]
Forced convection cooling inside an electronics enclosure
Introduction One of the more complex thermal problems in electronics is the modeling of complete systems, such as an enclosure containing electronic components. A typical example would be a power supply, including heat sinks and a cooling fan. This problem becomes more difficult when there are multiple heat sinks and other large components arranged in an arbitrary manner inside … [Read more...]
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