1997

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Thermal management of telecommunications cabinets

September 1st, 1997

Figure 1. Thermal analog model of an OSP enclosure Introduction Over the past twenty years, telecommunications electronics have become increasingly decentralized – moving ever furtherfrom the controlled and protected environment of the Central Office intothe…read more

Standardizing heat sink characterization for forced convection

September 1st, 1997

Figure 1. Wind tunnel configuration Introduction While there has been a flurry of activity inliterature addressing the behavior of heat sinks in computer electronics,the reusability of the data presented in these papers has been somewhatlimited…read more

One-dimensional heat flow

September 1st, 1997

The simplest heat flow situation is that described as “one-dimensional heat flow”. The Figure illustrates a one-dimensional heat flow situation. It shows heat flowing in one face of an object and out the opposite face.…read more

Integrated thermal network models are still useful

September 1st, 1997

Figure 1: Basic discretization of parallel board arrangement Introduction While electronic systems thermal managementgrows in complexity, the challenge of integrating thermal constraints intothe product design process remains constant. The evolution of compactcomponent models highlights the…read more

Highly emissive ion beam textured surfaces for improved cooling of electronic devices

September 1st, 1997

Continuous improvements in the cooling of electronic systems will berequired to keep pace with the rapid development of higher power chips.Currently, effective cooling relies (in part) on high surface area heatexchangers. Further improvements could be…read more

Coefficient of thermal expansion

September 1st, 1997

As complexity increases and dies and packages become even larger, temperature gradients also increase, leading to problems with thermal mismatch. Hence, thermomechanical analysis grows in importance. Apart from the temperature differences, the most important parameter…read more

A practical formula for air-cooled boards in ventilated enclosures

September 1st, 1997

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…read more

Thermal resistance: an oxymoron?

May 1st, 1997

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…read more

Thermal Conductivity

May 1st, 1997

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…read more

Packaging: designing for thermal performance

May 1st, 1997

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…read more

Forced convection cooling of airborne electronics

May 1st, 1997

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…read more

Calculating interface resistance

May 1st, 1997

Figure 1. Ceramic Package – Aluminum Heat SinkAssembly Introduction The exposed surface area of many of today’s high powered electronic packagesis no longer sufficient for the removal of the heat generated during normaloperation. Heat sinks…read more

A simple method to estimate heat sink air flow bypass

May 1st, 1997

Introduction After selecting or designing a heat sink based upon a given air velocity orvolumetric flow rate through the fins, the thermal designer needs to determinethe total amount of flow which must be delivered in…read more

Temperature measurement using optical fibers

January 1st, 1997

Introduction Fiber optic temperature measurement has been in use for decades1.The most prevalent methods are fluorescent and radiation thermometry, also knownas pyrometry. Fluorescent temperature measurement is used for lower-rangemeasurements from -200°C to +450°C. Pyrometry best…read more