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Ge2Sb2Te5 (GST)-based phase change memory (PCM) is a digital memory technology set to replace flash because of its greater scalability, lower programming power requirements, faster read-write times, and enhanced durability. Modeling efforts have focused on characterizing the coupled electrical, thermal, and phase-transition processes that define PCM switching events. Understanding the effects of device...
A study of the performance of different Sn based solder alloys applied for large to small sized solder interconnects was undertaken. From the theoretical and experimental investigations on creep, fatigue and brittle fracture behaviors the paper focuses on the low cycle fatigue performance in test and field thermal environments. Special focus was put on a newly developed highly creep resistant solder...
Microelectronic encapsulants exhibit evolving properties that change significantly with environmental exposures such as isothermal aging and thermal cycling. Such aging effects are exacerbated at higher temperatures typical of thermal cycling qualification tests for harsh environment electronic packaging. In this work, the material behavior changes occurring in flip chip underfill encapsulants (silica...
Shrinking chip feature sizes and increasing performance demands are resulting in non-uniform on-chip power dissipation. Sub-millimeter regions of high heat flux are developing with heat fluxes exceeding the average chip flux by a factor of six to ten and peak heat fluxes approaching 1000 W/cm2. These "flux-spots" can yield locally high temperatures ("hotspots") and extreme thermal...
Fluid flow and mixed (free and forced) convection heat transfer characteristics over a micro-sphere at moderate to high values of both Grashof and Reynolds numbers are numerically investigated at uniform wall temperature boundary condition. Although this topic is crucial in understanding the basic flow and heat transfer features about a miniature sphere, little attention was drawn into it in the open...
3D interconnect technology has attracted significant interest in the recent past as a means for enabling faster and more efficient integrated circuits (ICs). 3D integration relies on through-silicon vias (TSVs) and bonding of multiple active layers. While this approach provides several electrical benefits, it also offers significant challenges in thermal management. While some work has been done in...
Applications that exploit the exceptional transport properties of carbon nanotubes (CNTs) at practical length scales almost invariably require good contact of the CNTs with the contacting surface. For example, vertically aligned and dense arrays of carbon nanotubes have been demonstrated to be good thermal interface materials. However, interfacial resistance to thermal and electrical transport between...
The information technology industry, and consumers of the products and services stemming from the industry, has benefited from rapidly increasing computational performance for all classes of devices over the past several decades. With increased performance, the industry has also experienced a sharp increase in device-level energy consumption and power density. These trends are expected to result in...
In this paper, the performance of a parallel implementation of the phonon Boltzmann Transport Equation (BTE) is tested. Two three-phonon scattering models, the full scattering model and the anisotropic relaxation time model, are considered. The finite volume method is used to solve the Boltzmann Transport Equation (BTE) numerically. Two strategies are explored: spatial domain decomposition and phonon...
Sintered nanoscale silver paste was used as thermal interface material in an electronic package. Based on the microstructure of the sintered silver paste, die shear stress-strain curves and thermal cycling test results, a model combined with the model of Navarro-de los Rios and small cracks interaction physical model is put forward to predict the thermal fatigue lifetime of the sintered nanoscale...
Thermal simulation had been conducted on flip chip packages with copper heat spreader and better thermal performance was achieved. The copper heat spreader was able to enhance the heat spreading from the die but thermal performance was affected due to the thin layer of thermal interface materials. It was observed that thermal performance gain can be as high as 30% from heat spreader. Ansys thermo-mechanical...
In flip-chip package, the mismatch of thermal expansion coefficients between the silicon die, copper heat spreader and packaging substrate induces concentrated stress field around the edges and corners of silicon die during assembly, testing and services. The concentrated stresses result in delamination on various interfaces involving a range of length scales from hundreds of nanometers to millimeters...
This paper addresses the reliability of flip-chip on flex (FCOF) assemblies glued with an Ag-particle filled anisotropic conductive adhesive (ACA). As the description of FCOF failure gives still much scope for speculation, a physics of failure based approach is developed here, taking into account the changing thermo-mechanical properties of the ACA under temperature and moisture. A failure hypothesis...
A series of studies have been conducted for mechanical behavior of elastic thin films on compliant substrates. Under tension, the film may fracture by growing channel cracks. The driving force for channel cracking (i.e., the energy release rate) increases significantly for compliant substrates. Moreover, channel cracking may be accompanied by interfacial delamination. For a film on a relatively compliant...
For a given heat sink thermal resistance and ambient temperature, the temperature of an electronic device rises fairly linearly with increasing device heat flux. This relationship is especially problematic for defense electronics, where heat dissipation is projected to exceed 1000 W/cm2 in the near future. Direct and indirect low temperature refrigeration cooling facilitate appreciable reduction in...
This study compared thermal-hydraulic performance of a single-phase micro-pin-fin heat sink with that of a micro-channel heat sink having the same characteristic dimensions and operating under the same conditions. The objective was to explore the potential of micro-pin-fin heat sinks as an effective alternative to micro-channel heat sinks for dissipating high-heat-fluxes from small areas. The micro-pin-fin...
New blade chassis designs, with banks of aggregate fans and system-level thermal architectures which precisely manage airflow, have enabled a new level of energy savings for enterprise customers that extends beyond the system and offers an opportunity for new system thermal design principles. By reducing system airflow rate to an absolute minimum, system fan power is minimized. More significantly,...
Server's capabilities are increasing at or beyond the rate of performance improvement gains predicted by Moore's Law for the silicon itself. The challenge for the information technology (IT) owner is housing and operating all of this computational power in the data center. With more computational power in each unit volume, the industry is experiencing a significant increase in power density and hence...
This paper is a continuation of the study (Iyengar et al., 2007) that describes the comparison of numerically-predicted and experimentally- measured temperature distributions in a small data center test cell. The data center cell has a floor area of 900 ft2 and comprises one rack, one air-conditioning unit, and perforated tiles. The Computational Fluid Dynamics (CFD) results in study (Iyengar et al...
Predicting reliability of solder joints requires a thorough understanding of solder constitutive behavior. Recent studies on SnAgCu solder alloys have reported that pre-test conditions of aging-time and aging-temperatures can be factors that significantly affect solder constitutive behavior. The results presented here are a part of ongoing efforts to construct constitutive models that can predict...
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