By Topic

Semiconductor Thermal Measurement and Management Symposium, 1995. SEMI-THERM XI., Eleventh Annual IEEE

Date 7-9 Feb. 1995

Filter Results

Displaying Results 1 - 23 of 23
  • Proceedings of 1995 IEEE/CPMT 11th Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM)

    Save to Project icon | Request Permissions | PDF file iconPDF (199 KB)  
    Freely Available from IEEE
  • Achieving accurate thermal characterization using a CFD code: a case study of PLCC packages

    Page(s): 55 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    Achieving component-level thermal characterization using computational fluid dynamics (CFD) is assessed using a case study approach. The FLOTHERM code is used to simulate the thermal performance of three plastic-based components (68-lead and 84-lead Plastic Leaded Chip Carriers or PLCCs and a 164-lead Plastic Quad Flat Pack or PQFP) under forced air cooling conditions. Predictions of thermal resistance are compared to experimental measurements. One aspect of the work is to use results from a single situation (84-PLCC and an approach air velocity of 1.5 m/sec) to develop a set of “modeling guidelines”. These modeling guidelines are then be applied to the other components and flow conditions (0.76 to 3.05 m/sec) to test their validity. Guideline parameters include near component flow field nodalization, geometric detail in representing conduction paths and code user options such as turbulent flow models. The average deviation of predicted versus measured values of junction to ambient thermal resistance (θja) was 7.5% using the derived guidelines. An additional component design sensitivity investigated was the effect of the introduction of a heat spreading “heat post” in the high temperature regions of the 164-PQFP View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Experimental investigation of subcooled liquid nitrogen impingement cooling of a silicon chip

    Page(s): 115 - 121
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (600 KB)  

    A technique was developed to facilitate subcooled pool boiling and jet impingement boiling of liquid nitrogen at the surface of a silicon chip by varying the dewar pressure while maintaining the bath temperature constant at about 78 K. Subcooling levels of up to 10 K could be easily reached by pressurizing the liquid nitrogen bath with helium gas. Convective and boiling impingement cooling of up to 80 W/cm 2 from a silicon chip has been measured for a submerged subcooled liquid nitrogen jet View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Methodology for thermal evaluation of multichip modules

    Page(s): 72 - 79
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    Multichip modules provide shorter interconnection lengths between the chips, higher speeds and lower costs. This higher system performance is the driving force for advances in MCM packaging technology. A potential limitation is the ability to remove heat from these packages. With higher chip densities, the thermal management of multichip modules poses a real challenge to the package manufacturer. There is a need to define the junction-to-ambient and junction-to-case thermal resistances for multichip modules in a more rigorous manner while reducing the number of thermal tests needed to evaluate an MCM and provide information to predict junction temperatures under arbitrary powering up of the individual dice. For high reliability, it is critical that maximum specified operating junction temperatures are not exceeded. Experiments were performed for non-uniform powering up of an MCM mounted on a vertical board in natural convection. The package tested was a 208-lead Amkor PMCM. The average chip temperature due to multiple sources within the module was considered as the reference temperature for evaluating the junction temperature rise of the particular chip. The concept of superposition of temperatures was found to capture the effect of the background heating of the chip due to its neighbors as well as the individual power dissipation from the chip in question. This approach offers a more refined methodology for evaluation of non-uniformly powered multichip modules compared to previous methods View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect on observed package thermal performance of system board metal content

    Page(s): 31 - 36
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (516 KB)  

    In a growing number of customer applications, the ultimate success of a semiconductor package design is measured by its thermal performance. Unfortunately, thermal databases consisting of junction-to-ambient thermal resistance (θja) alone fall short of allowing the customer to adequately predict the actual thermal performance of a package, since the actual θja of a package is sensitive in varying degrees to the details of the system board on which the package is mounted. Though this fact is often acknowledged, the magnitude of the effect is generally not appreciated, and it is rare to find sufficient information in a product data sheet to allow such an evaluation. Variations in thickness and coverage of signal traces, power and ground planes, and insulating layers, can change the nominal θja of a package by from 25 to 50%. To illustrate this effect, several non-thermally enhanced Quad Flat Pack (QFP) type packages were mounted on several types and sizes of test boards, which were then both measured and modeled. Changes in overall θja are correlated with the metal content of the boards View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of a thermally enhanced ball grid array package

    Page(s): 146 - 155
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    A thermally enhanced ball grid array package (SuperBGA package) has been developed. Its thermal performance has been analyzed using a non-linear, lumped-parameter model. This model uses a temperature-dependent heat transfer coefficient which accounts for the natural, mixed, and forced convection regimes and radiative heat transfer. The accuracy of the model was verified experimentally using one package size. The model was then used to predict the thermal performance of other package sizes and to rationalize the high level of thermal performance exhibited by the package View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A study of chip thermal crosstalk in plastic VLSI packages

    Page(s): 37 - 38
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    Plastic VLSI packages are modeled as five-layer structure. Lateral boundaries are assumed to extend to infinity for a planar reference structure. With a small heat source on the silicon chip, calculation results show that the temperature profile on the chip decreases exponentially for distance greater than a specific value. An empirical temperature expression is thus established. The expression enables efficient calculation of temperatures at remote locations. These temperatures are important for large chip devices having large number of small heat sources View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A method of the BJT transient thermal impedance measurement with double junction calibration

    Page(s): 80 - 82
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    In the paper a new method of the transient thermal impedance measurement of the bipolar transistor (BJT) is presented. This method is based on the conception of the double calibration of the thermosensitive emitter junction at a small collector current and under the condition of the heating power dissipated in the device, respectively. The method presented belongs to the methods making use of the heating curve, but it is simpler (faster) in realisation than the standard methods View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Recent advances in thermal/flow simulation: integrating thermal analysis into the mechanical design process

    Page(s): 136 - 145
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (792 KB)  

    There has been increasing interest in and emphasis on the use of computer based analytical tools for simulation of thermal phenomena in electronic systems. Concurrent engineering of such systems demands the complete integration of analysis tools into parametric mechanical design software. Intelligent and associative integration between design and analysis activities can effect more rapid turnaround. Analysis can drive the design process and down-stream activities which alter the design will automatically update analysis models. A next generation system has been developed, based on proven simulation technology, that improves efficiency over currently available solutions. The package combines the intuitive characteristics of thermal network modeling with powerful computational fluid dynamics technology to model 3D fluid flow. Experimental thermal measurements for several cases are compared to values calculated by the system. Good correlation with experimental results is demonstrated for each of the test cases. In addition, the need for flexible modeling tools is demonstrated. Tools to facilitate an understanding of heat transfer and fluid flow are an essential part of the thermal engineering process View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High performance air cooling scheme using ducted microchannel parallel plate-fin heat sinks

    Page(s): 122 - 130
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (792 KB)  

    In this work a high performance air cooling scheme based on microchannel parallel plate-fin heat sinks, in which the coolant is ducted to and optionally from the heat sink through tubes, is theoretically and experimentally investigated. The performance in terms of thermal resistance, pressure drop, and pumping power is modeled as a function of heat sink dimensions, tube dimensions, and air flow rate. Optimizations are performed and design trade-offs discussed. A specimen heat sink with lateral dimensions of 5 cm×5 cm, with 150 μm thick fins, and with 300 μm wide channels was fabricated using copper foils and a simple assembly process. The performance of the heat sink was evaluated experimentally. A thermal resistance of approximately 0.2 K/W is achieved at a pressure drop of 12.5 mbar and an air flow rate of 5 l/s. The agreement between predicted and experimental results is found to be comparatively good. Results of the present study are compared to results of other investigations concerning direct air cooling. The achievable thermal performances using the investigated cooling approach are superior to those attainable using conventional air cooling schemes as well as to those employing silicon microcoolers View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The evolution of IBM high performance cooling technology

    Page(s): 102 - 114
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (980 KB)  

    This paper provides a perspective and review of the evolution of high performance cooling technology that has been developed and used in IBM medium and large-scale computers over the past 25 years. Package cooling technology and its evolution, leading to the development of the Thermal Conduction Module (TCM) is described. The development of air cooling technology is discussed; along with enhancements using turbulators, air-to-liquid heat exchangers, and impinging flow. The development of water cooling and direct liquid immersion technology is also covered View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Enhancement of convection cooling of integrated circuit components

    Page(s): 28 - 30
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (228 KB)  

    An experimental study is conducted of heated rectangular blocks cooled by forced convection in a horizontal channel. The experimental model represents a computer circuit board with heated chips. The investigated physical situation is presented schematically. In the grooved channel, two main flow regions can be recognized: (i) the main channel flow and the recirculating flow in the groove. In laminar, steady state conditions, there is no exchange of fluid between the two regions. The warm fluid is trapped in the groove, and the heat transfer is governed mainly by diffusion. The role of self-sustained oscillations in the enhancement of heat transfer is investigated. Passive solutions to improve heat transfer on the basic geometry will be explored. In order to efficiently exploit self-sustained oscillatory flows to improve heat transfer, good understanding of the underlying flow and heat transfer phenomena is essential View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 1995 cumulative bibliography of articles on semiconductor thermal and temperature testing

    Page(s): 156 - 183
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1952 KB)  

    The bibliography given consists of 629 articles covering semiconductor thermal and/or temperature characteristics, measurement techniques and results, hardware applications, and other pertinent information View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Asymptotic thermal analysis of electronic packages and printed-circuit board

    Page(s): 131 - 135
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB)  

    Electrical analogy to thermal networks is widely used to study thermal behavior of electronic components. For solution of Poison heat equation, this analogy usually leads to a large resistance-capacitance (RC) network. Conventional simulation techniques when applied to these networks require substantial computational resources. This paper presents new solution technique based on a recently developed Asymptotic Waveform Evaluation (AWE) concept which has been successfully used for simulation of large electrical networks. Applying AWE to thermal analysis of printed circuit boards results in two orders of magnitude speed-up with respect to current iterative techniques with comparable accuracy View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Thermal transient characterization of electronic assemblies by infrared thermography and Delta Vbemeter methods

    Page(s): 87 - 91
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    The severe operating environment of electronic systems, means that the design of electronic boards requires continual investigations, involving not only electronics but also thermal and thermomechanical studies. We present here two complementary experimental methods to characterize the thermal transient behaviour of electronic assemblies and we compare the results obtained. Then, we conclude by presenting the fields of applications for such test equipment View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Application of phase change materials for passive thermal control of plastic quad flat packages (PQFP): a computational study

    Page(s): 65 - 71
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (508 KB)  

    A transient three-dimensional analysis was performed for passive thermal control of a plastic quad flat package (PQFP) by incorporating phase change material (PCM) under the printed wiring board (PWB). Governing conservation equations for mass, momentum and energy were solved by an implicit finite volume numerical technique. The effects of phase change were modelled by a single domain enthalpy-porosity technique. To study the effects of thermal conductivity of the board, a total of four cases were considered with two different board materials. It was found that passive cooling with PCM can arrest the temperature rise for a substantial time, for the power level considered. A higher board thermal conductivity resulted in a reduction in temperature levels. The melt region for a lower thermal conductivity of the board was found to be localized near the package footprint, while, for a higher board conductivity, the melt region extends along the board View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A measurement methodology for laser-based thermal diffusivity measurement of advanced multichip module ceramic materials

    Page(s): 92 - 101
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (924 KB)  

    Alumina derivative ceramics and Low Temperature Co-fired Ceramic (LTCC) electronic MultiChip Module (MCM) packaging substrates have been thermally, optically and morphologically characterised. This paper focuses on the singleand double-sided inspection laser flash thermal diffusivity measurement techniques used to measure the thermal transport properties of the MCM ceramics, and in particular, on the measurement methodology required to measure the thermal diffusivity of these materials by a single-sided inspection laser flash diffusivity method. The paper highlights problems associated with both the measurement system and associated data analysis for the single-sided measurement and data are compared to those measured by an existing (double sided inspection) standard laser flash method. Finally, a preliminary measurement methodology is proposed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimum design and selection of heat sinks

    Page(s): 48 - 54
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (572 KB)  

    An analytical simulation model has been developed for predicting and optimizing the thermal performance of bidirectional fin heat sinks in a partially confined configuration. Sample calculations are carried out, and parametric plots are provided, illustrating the effect of various design parameters on the performance of a heat sink. It is observed that the actual convection flow velocity through fins is usually unknown to designers, yet, is one of the parameters that greatly affect the overall thermal performance of a heat sink. In this paper, a simple method of determining the fin flow velocity is presented, and the development of the overall thermal model is described. An overview of different types of heat sinks and associated design parameters is provided. Optimization of heat-sink designs and typical parametric behaviors are discussed based on the sample simulation results View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A method of using thermal test chips with diodes for thermal characterization of electronic packages without calibration

    Page(s): 83 - 86
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    For characterizing the thermal performance of electronic packages, specially designed thermal test chips are used. These test chips have heaters for powering and diodes for sensing the chip temperature during the test. Prior to tests, the diodes are calibrated and the calibration data consisting of voltage output (at a fixed constant current) versus temperature is usually fitted to a straight line. During the tests, the voltage output of the diode is measured (at the same fixed constant current) and the chip temperature is determined using the calibration curve. This paper reviews another method of using the diode for measuring the chip temperature without calibrating the diode first. In this method, the diode is operated at two different known current levels, I1, and I2, and the corresponding forward voltage drops, V1, and V2, are measured at a known temperature. At the unknown temperature the forward voltages are again measured at the same two current levels. Using a simplified form of Shockley's ideal diode equation, the difference in the forward voltages is used to determine the unknown temperature. Compared to the constant-current method, the current-switching method is more susceptible to measurement errors. However, it is relatively simple to use since it does not require calibration of the diode over the temperature range prior to use View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Influence of elastic and plastic contact models on the overall thermal resistance of bolted joints

    Page(s): 39 - 47
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    A bolted joint, which operates in vacuum is analyzed in this work. A resistance network, composed of material, contact and constriction resistances is presented for the overall thermal resistance of bolted joints. Thermal stress theory is used to determine contact stress variations with temperature level. Dimensional and non-dimensional forms of the thermal resistances and of the thermal stress models are given. Two contact resistance models, one based on the elastic and the other on the plastic deformation of contacting asperities, are used and their impact on the overall thermal resistance is studied View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An assessment of the thermal performance of the PBGA family

    Page(s): 17 - 27
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (936 KB)  

    The plastic Ball Grid Array (PBGA) has generated significant interest as a cost effective packaging alternative for high I/O ULSI devices. This study assesses thermal performance of the PBGA family using the metric of power dissipation capability-“power rating” for IC packages. The metric chosen is the power dissipated for constraints of junction temperature (<105°C), and board temperature (<90°C), in low aspect ratio enclosures (portable products), as well as natural and forced air convection (~1.0 m/s) equipment operating conditions. The free and forced air conditions are typical of PC/workstation environments. Simulation studies using a finite difference based software for thermal performance of IC packages investigated the relative roles of package enhancements towards the thermal performance. Experimental data for the 106 PBGA in free air and portable radio mockup, and the 119 PBGA in free and forced air were used to validate the methodology. The study covers 68 to 324 pincount PBGAs and compares the performance with comparable pincount PQFPs (plastic Quad Flat Package) and other contemporary package styles. The study also addresses system level enhancements for extending the thermal performance of PBGAs for applications. The power dissipation for PBGAs in portable products is projected at 0.6 W. The power dissipation capability of the PBGA is projected to lie in the range 1.5-1.75 W in free and forced air environments. Coupling a motherboard ground plane to the package thermal vias and bumps allows performance enhancement to 2.8 W. A heat-sink attached PBGA allows heat dissipation in excess of 8 W in high end systems. The thermal performance of the PBGA is comparable to PQFP-even when no advantage is taken of the package thermal vias and bumps by the system. Furthermore, the performance of the PBGA compares well with CPGA, CQFP and the CBGA packages View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Thermal characterisation of vertical multichip modules MCM-V

    Page(s): 10 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (700 KB)  

    This paper describes the thermal characterisation of a vertical multichip module (MCM-V) technology. The MCM-V technology encloses a stack of ICs in a three dimensional cube of plastic moulding compound with the inter-chip electrical connections made on the outside faces of the cube. Steady state and transient thermal results are presented. Thermal measurements were carried out on modules containing eight specially designed package evaluation test chips. Simulation results are shown for two applications manufactured in the MCM-V technology; a 2 W 16 chip 256 MBit DRAM module and a 3 W 9 chip image processing system View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A novel approach for the thermal characterization of electronic parts

    Page(s): 1 - 9
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (772 KB)  

    The accurate prediction of operating temperatures of temperature sensitive electronic parts at the component, board and system level is seriously hampered by the lack of reliable, standardized input data. The situation which prevails today is that component manufacturers supply to end-users experimental data which characterizes the thermal behaviour of packages under a set of standardized and idealized conditions. Such characterizations normally involve the junction-to-case thermal resistance or the junction-to-ambient resistance according to MIL or SEMI standards. There are several practical difficulties associated with such an approach, which will be briefly commented upon. Today, the need for more accurate junction temperature prediction becomes increasingly urgent, and the call for a precise definition of the various thermal resistances is heard by a growing number of researchers. The paper continues with a survey of the open literature and discusses the pros and cons of several methods that describe the thermal behaviour of electronic parts. It is concluded that none of these methods is capable of meeting the objectives that are proposed. A novel approach is introduced, based on the derivation of a simple resistance network starting from a detailed model using optimization techniques. The proposed method is applied to two cases: a so-called `validation' chip, functioning as a benchmark for the software that is used to generate the detailed model, and a 208-PQFP component. It is demonstrated that it is possible to create a compact model comprising a simple resistance network, representing the detailed model to a high accuracy which is independent of the boundary conditions View full abstract»

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