Fig. 1 - Ventilated cabinet Introduction Natural air convection is commonly applied as a cooling technique for electronic equipment of moderate power density such as telecommunication boxes. The main advantage of natural convection isits intrinsic reliability, because air movement is generated simply bydensity gradients, if an external body force field exists. However, due … [Read more...]
Thermal resistance: an oxymoron?
Introduction Dark light, deafening silence, cruel kindness, living dead, fuzzy logic,honest politics. The adjectives seem to contradict the substantives; such afigure of speech is called an oxymoron. It will be argued within this articlethat 'thermal resistance' is also a serious candidate for this category, atleast if the concept is being applied without realizing the … [Read more...]
Thermal Conductivity
For most calculations regarding the thermal analysis of electronic systems, thermal conductivities of solid materials are required. It is felt that many designers would welcome a comprehensive list showing these values for certain classes of objects, such as PCB materials, leadframes, molding compounds, alloys etc.. This issue starts with 45 leadframe materials, the data for … [Read more...]
Packaging: designing for thermal performance
Figure 1. Various leadframe and BGA packages Introduction The well-established trend within the electronics industry to provide everincreasing computing power at less cost seems to defy the laws of economics.However, this industry has not been able to suspend the laws of physics. Eachcalculation by each of the millions of transistors in the modern personalcomputer is … [Read more...]
Forced convection cooling of airborne electronics
Figure 1. AFT description Fin pitch = 25.01 per in = 985 per mPlate spacing, b = 0.200 in = 5.08 x 10-3 m Fin Length = 0.111 in = 2.8 x 10-3 m Flow passage hydraulic diameter 4rh = 0.004905 ft = 1.50 x 10-3 m Fin metal thickness = 0.004 in = 0.102 x 10-3 m Total heat transfer area/volume between plates, ß = 719.4 ft2 / ft3 = 2,360 m2 / m3 Fin area / total area = … [Read more...]
- « Previous Page
- 1
- …
- 472
- 473
- 474
- 475
- 476
- …
- 481
- Next Page »
