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The following topics are dealt with: semiconductor thermal measurement and management; thermal market and technology drivers for the future; two phase cooling; modeling and simulation; fans and pumps; microchannel cooling; die level cooling; thermal interface materials; innovative cooling; and package level cooling.
In this study, a three-dimensional, transitional simulated model of a one-side actuating micropump, based on an actual design, has been successfully developed to predict the flow rates and pump heads by changing actuator displacements and the coupling effects of valves under different frequencies. The grid deformation with two moving boundaries, including the PDMS diaphragm and the piezoelectric device,...
This paper discusses the possibility of estimating in real time internal heat source temperature values based on the sensor measurements available only at circuit boundaries. The chances and some fundamental limitations of such a boundary temperature scan approach are illustrated based on an example of a test ASIC. This circuit contains a matrix of heat sources which can be individually switched on/off...
Adding cores to CPU chip increases its power density and leads to thermal throttling due to cooling limitations. Thermal spare cores (TSC) is proposed as new technique for dynamic thermal management (DTM). Our objective is to avoid thermal throttling and ensure stable CPU performance. Towards this objective, thermal model of IBM Power 4 CPU chip contains 8 cores implemented as proof of concept. TSC...
With increased attention to energy costs for Data Centers, the Industry is investigating how this energy is being consumed and designing methods for reducing Data Center power consumption. The typical data center can require up to two times the useful computing power for cooling. The biggest of these data centers contain 400,000 servers and consume 250 megawatts of power. It has been estimated that...
In this paper a new measurement method is developed to determine the friction factors in microchannels. Based on a set of experiments at variable microchannel lengths the friction factor can be derived by least-squares fitting well-established pressure loss correlations. Furthermore, collector losses and developing flow regime can be identified. An experimental set-up is build to demonstrate this...
Cooling fans are a ubiquitous and often dominant source of noise emission for many products. Cooling requirements and chassis resistance influence not only the selection of the cooling fan, but also set a lower bound on noise emission. Typical manufacturers' noise emission data, obtained under optimal inflow free-air conditions, is of dubious value. Unpleasant surprises can occur when initial prototypes...
Telecommunication cabinets house numerous electronic components which dissipate heat to varying degrees. The thermal management of these components is of utmost importance in the design of these cabinets. CFD allows designers to try out and compare various cabinet configurations and enable an optimal design thus reducing unnecessary construction of cabinet prototypes and elaborate experimental tests,...
Fiber accumulation fouling of heat sinks is a growing issue within the electronics industry. Fouling can lead to significant decreases in cooling efficiency and may even cause equipment malfunction. Most existing dust studies focus on fine particle threats to human health or heavy machinery. Little attention is paid to the larger particles and fibers that human anatomy and heavy equipment typically...
Forced air cooling with rotary fans is the most popular cooling solution for electronic products. However, increasing heat generation in microelectronics, and the demand for ever smaller portable devices, has resulted in heat fluxes and form-factors that push the limits of conventional rotary fan-based air cooling technology. Electrohydrodynamic (EHD) ionic wind pumps offer an attractive alternative...
Saturated pool-boiling experiments at one atmosphere and sub-atmospheric pressure assess the utility of fine filament screen-laminate enhanced surfaces as effective bubble nucleation sites and bubble generators. Experiments were conducted on vertically oriented 4 cm2 copper test surfaces in saturated distilled water at pressures of 0.2 atm., 0.3 atm., 0.5 atm., and 1 atm. Boiling performance characteristics...
A thermoelectric air-liquid cooling system has been built to provide 1.6 KW cooling capacity at 1.0 KW input power when the inlet temperatures of the air and liquid are 30 C. Instead of using commercially available thermoelectric (TE) modules, this system integrates the TE elements and shunts directly into heat exchangers. The TE connectors (shunts) are in direct contact with the heat exchangers,...
Pool boiling experiments are conducted to investigate the heat transfer performance of screen laminate-enhanced extended surfaces in water at reduced pressures. Screen laminations of varying pore hydraulic diameter and specific surface area fine wire screen are bonded to an extended surface (fin). The fins have a 1 cm2 base cross section area, a 5 deg taper with heights of 1 cm and 2/3 cm. Pool temperatures...
Nowadays the demand for thermal standards for power LEDs is increasing. On the one hand metrics for fair comparison of competing products are needed; on the other hand, designers of power LED-based applications demand reliable and meaningful data for their daily work. Today's data sheet information does hardly meet any of these requirements. In earlier papers we compared the current situation in the...
Electrically conductive adhesives (ECA) are popular solutions for joining relatively large (> 500 mum) electrical interfaces or when lower-temperature requirements preclude soldering or brazing. When assembled by squeezing between two flat, rectangular surfaces, the flow dynamics of the conductive filler and matrix can induce variations in local electrical conductance. This becomes significant...
The evolution of microprocessor architectures has driven semiconductor manufacturers making transition from ceramic to organic package substrate technology in order to take full advantage of the silicon advances. However, large mismatch in coefficients of thermal expansion (CTE) between silicon die and organic substrate results in significant die/package warpage that adversely impact the package's...
Thermal characterization of a package-on-package (PoP) presents a challenge due to the variation in stacking configurations. Currently available characterization methods as outlined in the JESD51 standard cannot predict die temperatures for packages with more than one die, let alone multiple stacked packages. A model is presented to predict die temperatures for PoP by combining individual resistor...
A study was initiated in order to thermally quantify the characteristics of package-on-package (POP), which has been deployed in multiple mobile devices in order to reduce board area and subsequently mobile device size. In most POP scenarios, the memory package is stacked on top of a baseband or application processor and reflowed together. Thermal simulations were conducted for a POP package configuration...
An issue often raised by engineers regarding thermal interface materials (TIM) is that vendor data do not match the results obtained from actual applications. Typical reasons for these issues may be vendor variations in testing, such as variances in test procedure and setup. This study compares vendor data from various vendors with results obtained from both realistic and ideal test conditions under...
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