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Current trends in data center cooling infrastructure design drive toward raising the coolant temperature to as high a level as equipment reliability allows in order to reduce the energy consumed by the cooling infrastructure and, consequently, improve (i.e., decrease) the power utilization effectiveness (PUE). However, as currently applied, PUE would appear to have deteriorated if measures are taken...
A holistic system-level analysis of the energy and mass transfer in a data center cooling system is used to determine the exergy destruction by each component in the system. The analysis, performed using our in-house analysis code, allows for identification of system inefficiencies and comparison of the energy efficiency of different data center cooling strategies. In this paper, we describe a systematic...
The effect of solder joint size on wafer level chip scale package reliability has been studied through simulation. A two dimensional finite element model with different solder diameter (250µm, 300µm, 350µm) was studied under accelerated thermal cycling. The failure of the solder joints under thermal fatigue loading is influenced by the solder joint size. Finite element modelling can be used to study...
Solid-state lighting (SSL) products can have a predicted life of 70% lumen output (L70) from 26,000 to 40,000 hours using the LM-80-08 testing standards. Chromaticity shift, correlated color temperature (CCT) and lumen maintenance (LM) will dramatically reduce the nominal life of SSL luminaires. In this work, an off-the-shelf luminaire from Philips (AmbientLED) has been aged in a standard wet hot...
We present an experimental study of thermal conduction in 1 µm thick suspended CVD diamond film by time-domain thermoreflectance (TDTR), an optical pump-probe technique. Important aspects of signal analysis and measurement sensitivity are discussed, outlining the various thermal metrology challenges posed by this system. We measure the properties of the near-interfacial coalescence region and high-quality...
Wire bonding is predominant mode of interconnect in electronics packaging. Traditionally material used for wire bonding is gold. But industry is slowly replacing gold wire bond by copper-aluminum wire bond because of the lower cost and better mechanical properties than gold, such as high strength, high thermal conductivity etc. Numerous studies have been done to analyze failure mechanism of Cu-Al...
An investigation of a solid-state lighting (SSL) luminaire with the focus on the electronic driver which has been exposed to a standard wet hot temperature operating life (WHTOL) of 85% RH and 85°C in order to assess reliability of prolonged exposer to a harsh environment has been conducted. SSL luminaires are beginning introduced as headlamps in some of today's luxury automobiles and may also be...
The trends towards miniaturization in the electronics industry coupled with advances in flip chip technology have increased the use of flip chip on board or direct chip attach technology in many products. This is especially true for products where re-work is not an option. Reliability issues were overcome by the use of underfill to couple the chip to the substrate and subsequently significant advances...
Analytical models of stress and deformxation of through-silicon vias (TSV), relative to numerical ones, have the advantage of being inexpensive to evaluate and in providing insight. They have the additional advantage of allowing one to embed them in ECAD tools for real time design decisions. Motivated by this reasoning, in this paper, an analytical model for the three-dimensional state of stress in...
The thermal conductivity of single crystal silicon can be reduced by the introduction of boundaries at the nanoscale. We present the measured thermal conductivity of single crystal silicon nanobeams patterned with a single row of holes at room temperature: the hole diameter and the spacing vary from 100nm to 250nm and from 200 nm to 800nm, respectively. A steady-state four-probe joule heating measurement...
Laminar mixed convection heat transfer in a two dimensional symmetrically and partially heated vertical channel is investigated. The heated portions exist on the both walls of channel and their temperature is constant. The number of the heated portions is changed from 2 to 4 for each wall; however the total length of the heated portions is fixed. The fluid inlet velocity is uniform and air is taken...
In the last years the Detector Technology group (PH-DT) [1] of the CERN Physics Department in Geneva, Switzerland, has started the study of novel micro-fluidic cooling systems obtained through standard micro-fabrication processes that outperform traditional cooling approaches for the thermal management of silicon particle detectors. The fabrication of the cooling devices starts with the etching of...
The mechanical properties of polymer materials are often a key concern of the microelectronic packaging industry. The theoretical analysis of stress, strain, and deformation induced in electronic assemblies due to environmental exposures such as moisture adsorption, isothermal aging, and thermal cycling require the complete characterization of mechanical properties and constitutive behavior of the...
Reliable, consistent, and comprehensive material property data are needed for microelectronics encapsulants for the purpose of mechanical design, reliability assessment, and process optimization of electronic packages. Since the vast majority of contemporary underfills are epoxy based, they have the propensity to absorb moisture, which can lead to undesirable changes in their mechanical and adhesion...
Digitized Heat Transfer (DHT) is a relatively new and promising form of thermal management that uses discrete droplets to remove excess heat. In this investigation, DHT is studied using infrared thermography to measure the heat transfer to a digitized flow in a microchannel that is subject to a constant heat flux. Results show that heat transfer, characterized by Nusselt number (Nu), exhibits an initial...
The performance of thin-film evaporative cooling for near-junction thermal management was investigated. A liquid delivery system capable of delivering water in small volumes ranging 20∼75 nl at frequencies of up to 600 Hz was established. On one side of the silicon chip, a resistive heating layer of 2 mm × 2 mm was fabricated to emulate the high heat flux hot-spot, and on the other side a superhydrophilic...
In this work, a new wedge delamination technique for measurement of interfacial fracture strength is presented. This method can be implemented to assess the interfacial fracture behavior of underfill and silicon in flip-chip packages. Our method offers substantial advantages over traditional interfacial test methods which can be difficult to implement on brittle materials like silicon die. The efficacy...
Nanoengineered structures have received significant attention due to the application of porous media convection structures. Metal porous structures provide unique combinations of large surface to volume ratio, high conductivity, and mechanical compliance. The integration of metal porous structures can improve the performance of convective heat exchangers for high heat flux thermal management. Copper...
Phase separation in two-phase microfluidic exchangers is a promising strategy for reducing the required pumping power. Past research has focused on using hydrophobic nanoporous structures in order to extract water vapor and retain liquid within the vapor-cooling device. This study focuses on characterizing the bursting pressure, the maximum Laplace pressure for liquid containment, of nanoporous alumina...
The development of embedded and interlayer liquid cooling in integrated circuits (ICs) using silicon microchannels has gained interest in the recent years owing to the rise of on-chip heat uses that aggravate thermal reliability issues of the emerging 3D stacked ICs. Further development of such devices and their translation to commercial applications depend largely on the availability of tools and...
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