By Topic

Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM), 2012 28th Annual IEEE

Date 18-22 March 2012

Filter Results

Displaying Results 1 - 25 of 70
  • [Front cover]

    Page(s): c1
    Save to Project icon | Request Permissions | PDF file iconPDF (181 KB)  
    Freely Available from IEEE
  • [Spine]

    Page(s): c2 - c3
    Save to Project icon | Request Permissions | PDF file iconPDF (67 KB)  
    Freely Available from IEEE
  • [Title page]

    Page(s): i
    Save to Project icon | Request Permissions | PDF file iconPDF (146 KB)  
    Freely Available from IEEE
  • [Copyright notice]

    Page(s): ii
    Save to Project icon | Request Permissions | PDF file iconPDF (99 KB)  
    Freely Available from IEEE
  • Welcome to IEEE SEMI-THERM 28

    Page(s): iii - iv
    Save to Project icon | Request Permissions | PDF file iconPDF (194 KB)  
    Freely Available from IEEE
  • ST28 organizing committee

    Page(s): 1
    Save to Project icon | Request Permissions | PDF file iconPDF (221 KB)  
    Freely Available from IEEE
  • Awards

    Page(s): 1
    Save to Project icon | Request Permissions | PDF file iconPDF (199 KB)  
    Freely Available from IEEE
  • Exhibitor listing

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | PDF file iconPDF (536 KB)  
    Freely Available from IEEE
  • Vendor workshops

    Page(s): 1 - 2
    Save to Project icon | Request Permissions | PDF file iconPDF (212 KB)  
    Freely Available from IEEE
  • Doubletree San Jose hotel layout map

    Page(s): 1
    Save to Project icon | Request Permissions | PDF file iconPDF (699 KB)  
    Freely Available from IEEE
  • Sponsors

    Page(s): 1
    Save to Project icon | Request Permissions | PDF file iconPDF (554 KB)  
    Freely Available from IEEE
  • Table of contents

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | PDF file iconPDF (117 KB)  
    Freely Available from IEEE
  • Measurement of microbump thermal resistance in 3D chip stacks

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (758 KB) |  | HTML iconHTML  

    The thermal resistance of Pb-free ~25 μm diameter microbumps with pitches of 50, 71, and 100 μm has been measured with and without underfill in four high chip stacks. With underfill, the unit thermal resistance values were 8.0, 15.5, and 19.0 C-mm2/W for 50, 71, and 100 μm pitch microbumps, respectively. The average microbump height was 16.1 microns. For the 50 μm pitch case, the thermal conduction through the underfill is roughly equal to that of the microbumps alone. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Experimental thermal resistance evaluation of a three-dimensional (3D) chip stack, including the transient measurements

    Page(s): 8 - 13
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (391 KB) |  | HTML iconHTML  

    For the thermal management of three-dimensional (3D) chip stack, its thermal resistance needs to be clearly understood. In this study, 3D stacked test chips are fabricated, which are implemented with PN junction diodes for temperature sensors and diffused resistors for heating. At SemiTherm2011, the equivalent thermal conductivity of the interconnection, including BEOL (Back-End-Of-the-Line, wiring layer) is experimentally obtained to be 1.6W/mC and this time, we measure the thermal effect of Cu TSVs and it is experimentally supported that as the Cu TSV area ratio increases, the thermal conductivity of chip with TSVs in the vertical direction increases, on the contrary, that in the horizontal direction decreases. Also, the transient thermal measurement is performed and its result is compared with steady state measurement result. Further, the thermal capacitance measurement of 3D stacked test chip with hot spot heating is performed, which is essential to determine the transient thermal performance of 3D chip stack. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Impact of die-to-die thermal coupling on the electrical characteristics of 3D stacked SRAM cache

    Page(s): 14 - 19
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1811 KB) |  | HTML iconHTML  

    We study the thermal coupling in a 3D stack with multiple cores in one tier and an SRAM array (cache) in a second tier with face-to-back bonding. For identical statistical distribution of power dissipation in cores, the SRAM sub-arrays experience much higher mean and variance in temperature in a 3D stack compared to a conventional 2D system. The increased variability in temperature increases leakage, degrades performance, and accelerates aging in 3D integrated SRAM. This is studied using 32nm predictive technology. Further, the spatial and temporal variations in performance of SRAM blocks become a strong function of the power variations in cores. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dynamic Compact Thermal Model for stacked-die components

    Page(s): 20 - 28
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (450 KB) |  | HTML iconHTML  

    The present work proposes an approach to generate Dynamic Compact Thermal Models or “DCTMs” dedicated to electronic components. This one is based on the European project DELPHI, which defined the first comprehensive methodology concerning the generation of thermal behavioral model, Boundary Condition Independent, called Compact Thermal Models or “CTMs”. Unfortunately, the scope of “CTMs” was limited to the steady state as well as for single chip packages. But, the latest trend toward higher and higher density packaging using several chips requires henceforth a methodology capable to take into account the transient regime for 3D integration technologies like stacked-die solution. Following the CTM's modus operandi the DCTMs were conceived to propose a RC network able to predict a set of sensitive component temperatures with a minimized difference during component duty cycle. This work suggests the use of the genetic algorithms fitting technique that turns out relevant for the realization of DCTM, as well as the conventional DELPHI CTM. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Two-phase flow control of on-chip two-phase cooling systems of servers

    Page(s): 29 - 35
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB) |  | HTML iconHTML  

    Thermal designers of data centers and server manufacturers are showing a great concern regarding the cooling of new generation data centers, which are more compact and dissipate more power than is currently possible to cool by conventional air conditioning systems. With very large data centers exceeding 100 000 servers, some consume more than 50 MW [1] of electrical energy to operate, energy which is directly converted to heat and then simply wasted as it is dissipated into the atmosphere. A potentially significantly better solution would be to make use of on-chip two-phase cooling [2], which, besides improving the cooling performance at the chip level, also adds the capability to reuse the waste heat in a convenient manner, since higher evaporating and condensing temperatures of the two-phase cooling system (from 60-95°C) are possible with such a new green cooling technology. In the present project, two such two-phase cooling cycles using micro-evaporation technology were experimentally evaluated with specific attention being paid to energy consumption, overall exergetic efficiency and controllability. The main difference between the two cooling cycles is the driver, where both a mini-compressor and a gear pump were considered. The former has the advantage due to its appeal of energy recovery since its exergy potential is higher and the waste heat is exported at a higher temperature for reuse. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Numerical prediction of the junction-to-fluid thermal resistance of a 2-phase immersion-cooled IBM dual core POWER6 processor

    Page(s): 36 - 44
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (625 KB) |  | HTML iconHTML  

    The numerical model used in development of the CPU cold plates for the water-cooled IBM p575 supercomputer is used in this work to predict the junction-to-fluid performance capabilities of passive 2-phase immersion cooling for the same p575 chip module. Experimentally-determined boiling heat transfer coefficients for a porous copper boiling enhancement coating (BEC) were used as a convective boundary condition applied atop the lid in place of the cold plate and secondary thermal interface. The BEC produces 75% and 1500% increases, respectively, in the critical heat flux (CHF) and peak heat transfer coefficients relative to a smooth surface. Lid thicknesses, 3.75mm<;t<;10mm, were modeled at the peak module power of Qm=158W. A thickness of t=3.75mm eliminated regional dryout of the BEC and yielded the optimal sink-to-fluid thermal resistance based on the lid temperature over the centerline of the chip of Rsf=0.073°C/W, a value consistent with previous measurements based on electric heaters similar in size to the P6 core. The resultant average junction-to-fluid thermal resistance was Rjf=0.174°C/W, ~10% lower than the junction-to-water inlet resistance, Rjw,i previously modeled for a single water-cooled cold plate used in the production p575. Immersion system level performance was estimated by assuming that 50% of the volume used for heat sinks in an air-cooled version of the p575 node was available for condensation. The analysis showed roughly equivalent performance to the water-cooled node if the same isolated rack water is used to condense the vapor. If facility water is instead used to condense the vapor directly and at the rack scale, pumps and much of the cooling hardware could be eliminated and the facility water temperature could be raised. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Thermal performance of sub-atmospheric loop thermosyphon with and without enhanced boiling surface

    Page(s): 45 - 51
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (539 KB) |  | HTML iconHTML  

    This experimental study comparatively examines the thermal performances of two-phase loop thermosyphons (TPLP) with and without enhanced boiling surface at sub-atmospheric pressures. The boiling instabilities along with the constituent and total thermal resistances of these TPLPs are analyzed with the aid of boiling flow structures imaged at sub-atmospheric pressures. Boiling heat flux (Q) and thermal resistance of condenser (Rth,con) are selected as the controlling parameters with their individual and interdependent effects on the thermal performances examined. With the present enhanced boiling surface, the intermittent bursting of large bubbles from liquid pool in the multi-channel evaporator of plain surface is significantly suppressed, leading to the moderate pressure waves agitated by bubble eruptions with reduced boiling instabilities and pressure-drop thermal resistances (Rth,ΔP). The effects of TPLP height (H), which affects the driven pressure head for liquid-vapor circulation, on the thermal performances of the enhanced TPLP at various Q and Rth,con are subsequently examined. Total thermal resistances (Rth) measured from the TPLTs with enhanced boiling surface are considerably reduced from the TPLTs with plain boiling surface and reduced to about 0.265 at the test condition of Q=150W, Rth,con=0.2, H=35.3 tube diameters. A set of Rth correlation which permits the evaluation of individual and interdependent Q, Rth,con and H impacts on total thermal resistances of the enhanced TPLPs is generated to assist the design activities using this type of enhanced TPLP for cooling of electronic chipsets. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High-performance nickel wick development for loop heat pipes

    Page(s): 52 - 57
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1165 KB) |  | HTML iconHTML  

    In the present investigation, high-performance capillary pump has been developed and evaluated for using inside loop heat pipes with 500 W heat transfer capability up to distance of 250 mm. Wick structure is one of the most critical components of the loop heat pipe that provides the necessary capillary pumping, liquid-vapour phase separation and heat leak barrier from evaporation section to the compensation chamber. In order to fabricate wick structure with appropriate physical characteristics, highly pure (>; 99.5%) nickel powders with average particle sizes of 2, 10, 12 and 75 μm were selected for sintering experiment. It was established that nickel powder can be effectively sintered when maintained at 750 - 850 °C temperature for one hour. Out of four nickel powders, NM-12 powder with average particle diameter of 12 μm was able to provide most qualified porous structure, sintered at 850 °C for one hour, with high porosity (>; 72 %), high permeability (>; 2 × 10-13 m2), finer pore radius (>; 7.2 μm), low shrinkage (<; 22%), good axial straightness and acceptable strength. The main issues faced in sintering trials and remedies to avoid them are explained in detail. Center rod extraction was the major problem faced in the sintering experiment which was rectified by replacing carbon rod with high strength, lubricious center rod made from stainless steel with boron nitride coating. The methodologies development in this study can be used for the fabrication of high performance capillary wicks for miniature to large-scale loop heat pipes. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A comparison analysis of air, liquid, and two-phase cooling of data centers

    Page(s): 58 - 63
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (667 KB) |  | HTML iconHTML  

    This paper provides analysis of air vs. liquid and two-phase flow cooling for a data center application. A new micro channel-based forced convection evaporation cooling is introduced, and its performance is compared against single phase and conventional phase change cooling systems. The technique offers substantially reduced thermal resistances with associated pumping power requirements significantly below that of conventional systems. It removes the need for compressors in a typical phase change cooling as it relies on a combination of forced convection boiling and thin film evaporation mechanism. Comparison analysis of the three techniques may provide additional incentives for adoption of energy efficient liquid cooling in next generation data centers. Issues remaining with large scale adoption of liquid and phase change cooling in data centers are also addressed in this paper. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Design and management of data center effectiveness, risks and costs

    Page(s): 64 - 68
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1889 KB) |  | HTML iconHTML  

    Data centers have been cooled for many years by delivering cool air to the IT equipment via the room. One of the key advantages of this approach is the flexibility that it provides the owner / operator in terms of equipment deployment. In principle it seems that all that is necessary is to determine the maximum power consumption of the equipment and provide an equivalent amount of cooling to the data center. Why then, since we have been building and operating data centers for decades using air cooling, do data centers experience hot spots, operate inefficiently and fail to reach their design expectations for capacity? This paper explains some of the challenges faced in the search for the perfect data center. In particular it identifies why, given the variability of equipment design and the time varying nature of the data center load, Computational Fluid Dynamics (CFD) should be used for airflow and heat transfer modeling. It shows that although it is not the only tool to be used in design and / or management of a data center, it is an essential tool to avoid lost capacity due to inability to efficiently cool equipment and the resulting potential for overheating. Important themes include a strategy that encompasses the entire life cycle of the data center, the need for an appropriate level of detail and the critical requirement for model verification and calibration. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Novel 3D electro-thermal robustness optimization approach of super junction power MOSFETs under unclamped inductive switching

    Page(s): 69 - 73
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (511 KB) |  | HTML iconHTML  

    This paper presents a novel approach to optimize the electro-thermal robustness of a super-junction power MOSFET under unclamped inductive switching (UIS) conditions. The loosely coupled electro-thermal simulation has been used to predict accurately the interaction between the core active device and the termination rings. The simulation results have been validated by the emission microscopy (EMMI) measurements and the transient IR thermography photos. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Energy reduction in server cooling via real time thermal control

    Page(s): 20 - 27
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (967 KB) |  | HTML iconHTML  

    Currently, server fans often over-cool the CPUs, contributing to increased use of energy. A thermal model-based real-time fan controller was studied in this paper to reduce the energy consumption in server CPU fans. A reduced order model of the server CPU and its heatsink was developed using proper orthogonal decomposition (POD), which provided 180 times faster simulation times, with reasonable accuracy. This was used in conjunction with a fan control strategy to achieve 27% savings in energy consumed for cooling. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A case study on the impact of free air cooling on telecom equipment performance

    Page(s): 82 - 86
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (365 KB) |  | HTML iconHTML  

    Energy consumption and its environmental impacts have become key concerns in the telecommunications industry and its data centers. As an energy-efficient approach for cooling, some data centers are adopting free air cooling, which uses ambient air outside the data centers, rather than air conditioning, to cool the electronic equipment. Traditionally, telecom equipment qualifications are based on passing a set of tests of industry standards that assume pre-defined environmental conditions. However, free air cooling changes the operating conditions and may go beyond those pre-defined conditions, which may affect the reliability and performance of the telecom equipment. This paper evaluates impact of free air cooling on the performance of telecom equipment. It compares the performance variations of telecom equipment under free air cooling with those under the traditional air conditioning to identify the impact of free air cooling on the telecom equipment performance. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.