The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Access networks provide the last mile of connectivity to telecommunication customers throughout the world. Voice, data, and video services through fiber, copper and wireless media are all delivered to the end user by the access portion of the network. In an access network, thermal management of active electronics and optical devices are critical to network reliability and performance. The outside...
Previous studies show that the lighting quality of LED largely depends on operating temperature. LED without thermal management may fail early due to thermal runaway, epoxy degradation, and thermal stress under high-operating temperatures. In this study, the performance of a honeycomb heat sink was investigated by experimentation and three-dimensional numerical models. Two kinds of honeycomb models...
Different high-end white power LEDs from different LED vendors were studied. The aim of the study was to find the optimal choice of LEDs and thermal management solutions for a street-lighting application. The primary concern was the (real) junction-to-heatsink thermal resistance of the LED or LED assembly and the real junction temperature and the actual light output of the individual LEDs under test...
It's proved that the physical meaning of the electrical average temperature rise of series LED array system tested by electrical temperature sensitive parameter (TSP) method is the arithmetic mean of the temperature rises of all sub-LEDs in the system. Based on this relationship, a novel method to evaluate the temperature distribution of series LED systems by scan measurement and recursive calculation...
There are several ways to define the junction-to-case thermal resistance; however, it is rather challenging to characterize the heat-flow in a package by a single number in an accurate and reproducible way. For many power package families such as TO-type packages the thermal transient testing and the so-called dual interface method can give reliable results. The diverging point of structure functions...
Thermal interface materials (TIMs) are widely used as heat conductive medium between a heat source and a heat dissipating device. A high thermal performance TIM can provide a low thermal resistance path and thus improve the thermal management of the heat source. This paper presents various criteria for TIMs used in silicon validation environment in addition to the well-known criteria for high performance...
This paper discusses the economic and environmental merits of passive 2-phase immersion in semi-open baths of dielectric fluid for cooling datacom equipment such as servers. The technique eliminates the need for hermetic connectors, pressure vessels, seals and clamshells typically associated with immersion cooling and the connectors, plumping, pumps and cold plates associated with more traditional...
Increasing thermal demands of high-end servers require increased performance of air-cooling systems in order to meet industry requirements. Increased air cooling performance will be attained through efficient distribution of the air flow to multiple electronic modules and improved aerodynamic power conversion efficiency of the server air movers and incorporating inter-stage air flow directional control...
This paper describes a 1 mm thick substrate with integrated flow channels to circulate liquid metal that is pumped with an electromagnetic pump. The substrate was fabricated using conventional circuit board assembly methods. Tests were performed with pumping current of up to 10 amps, which corresponded to a pumping power of 450 mW. This testing showed that the substrate had an effective thermal conductivity...
Electronic devices continue to shrink in size while dissipating more heat. The size of the air cooled heat sinks required to remove this heat has increased while the size of the heat source has decreased. These trends have resulted in large conduction gradients across the base of the heat sinks, resulting in decreased thermal performance. A passive and reliable method of minimizing the spreading resistance...
Convection remains the most popular cooling solution for portable consumer electronic devices. However, increasing heat generation in microelectronics and the demand for increasingly compact devices has resulted in heat fluxes that are pushing the limit of conventional rotary fan air cooling technology. Electrohydrodynamic (EHD) ionic wind pumps offer a possible solution. In this technique, applying...
Thermoreflectance microscopy is a well established method for the thermal imaging of (opto)electronic components and ICs. The technique combines submicron spatial resolution with excellent temperature resolution (10mK can be achieved). The dynamic thermal behavior can be studied using either a transient pulsed boxcar or frequency domain approach, the latter including homodyne and heterodyne lock-in...
A carbon-based, aluminum composite material with low mass, high thermal conductivity and low coefficient of thermal expansion (CTE) has been developed and characterized in this study. The carbon-aluminum composite is fabricated by injecting molten aluminum into a porous graphitic carbon matrix using a high-pressure impregnation process. The CTE of the carbon-aluminum composite is 7 ppm/K, and the...
The increasing importance of Solar Photovoltaic Cells in the world energy arena has created the need for thermal measurements of these devices. While no thermal measurement standard currently exists specifically for photovoltaic cells, the semiconductor junction devices are basically diodes and there are diode thermal measurement standards and approaches that can be applied to junction photovoltaic...
Light Emitting Diodes (LEDs) are increasingly being designed into lighting products for general illumination and are now gaining traction in the market. Several LED products are already available, but have generally been accepted only for low light level applications because of the low lumen output and poor quality of light for many of the products. Much of the reason for the low lumen output is the...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.