By Topic

Components, Packaging, and Manufacturing Technology, Part A, IEEE Transactions on

Issue 4 • Date Dec. 1997

Filter Results

Displaying Results 1 - 21 of 21
  • Foreword SEMITHERM XIII

    Publication Year: 1997 , Page(s): 382 - 383
    Save to Project icon | Request Permissions | PDF file iconPDF (22 KB)  
    Freely Available from IEEE
  • The world of thermal characterization according to DELPHI-Part I: Background to DELPHI

    Publication Year: 1997 , Page(s): 384 - 391
    Cited by:  Papers (34)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (108 KB)  

    The accurate prediction of the temperatures of critical electronic parts at the package, board and system level is seriously hampered by the lack of reliable, standardized input data that characterize the thermal behaviour of these parts. The recently completed collaborative European project DELPHI has been concerned with the creation and experimental validation of thermal models (both detailed and compact) of a range of electronic parts, including mono-chip packages, heat sinks, electrolytic capacitors, transformers, and interfacing materials. The ultimate goal of the DELPHI project was to get component manufacturers to supply validated thermal models of their parts to end users by adopting the experimental techniques used to validate the detailed thermal conduction models of the parts, and the methods to generate compact models. Part II of this paper contains technical information on both experimental and numerical methods. In order to reduce design-cycle time and physical prototyping, equipment manufacturers need to ascertain the thermal performance of new systems at the earliest possible stage of the design process. Accurate, validated thermal models of the critical parts used in the design are needed to provide the thermal precision necessary to design out the functional and reliability failures that result from component overheating View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High power multichip modules employing the planar embedding technique and microchannel water heat sinks

    Publication Year: 1997 , Page(s): 432 - 441
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB)  

    This paper describes a novel packaging technology for high power multichip modules (MCMs). The work covers three areas: The fabrication of a multichip module which provides access to the die backside for heat removal, the development of high performance microchannel heat sinks with a matched CTE, as well as a low thermal resistivity assembling technology. The MCM is fabricated by means of the planar embedding technology. By planarizing the module backside a low thermal resistance between heat sink and dice can be accomplished simultaneously for all embedded components. A thermotest module of size 2×2 capable of a power dissipation of several hundred watts was fabricated. Thermal resistance values below 0.6 Kcm2/W at 50 W/cm2 chip flux have been achieved View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • CFD applied to electronic systems: a review

    Publication Year: 1997 , Page(s): 518 - 529
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    The application of commercial and noncommercial computational fluid dynamics (CFD) programs to systems relevant to electronics is reviewed. The following commercial programs are discussed: THEBES, FLOTHERM, FLUENT, FLOTRAN, FIDAP/ICEPAK, CFX 4 (formerly CFDS-FLOW3D), PHOENICS/HOTBOX, and STAR-CD. Notably, of the noncommercial programs, work utilizing a spectral element program originating from the Massachusetts Institute of Technology (MIT) is described. General thermofluid capabilities, user friendliness, and other peripheral aspects, such as the modeling of thermal stress/strain and dust transport are assessed. For all comparisons with measurements, agreement was found to be within 30%. No commercial CFD program appeared to be clearly superior for all applications, but FLOTHERM had the most use for realistic cooling design problems View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Compact air-cooled heat sinks for power packages

    Publication Year: 1997 , Page(s): 442 - 451
    Cited by:  Papers (7)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB)  

    The main findings of a theoretical and experimental work carried out in the development of compact air-cooled heat sinks tailored for spot-cooling of power packages are presented. After formulating the particular cooling task, the thermal issues and practical constraints of a compact heat exchanger design are matched to yield three structures, i.e., microchannel, woven wire screen and porous metal fiber, to be viable candidates. A simplified analytical model is developed to allow performance analyses and optimizations of microchannel and woven wire screen heat sinks operated in impingement mode. Based on the simulation results, five novel heat sinks are fabricated and tested. An experimental setup is built to investigate the effects of heat sink structure, mass-flow rate of air, power dissipation and mounting conditions on heat sink performance. In the measurements the source-gate voltage of the selected MOSFET is used as temperature sensitive electrical parameter (TSEP) to obtain the peak junction temperature. Dissipated base plate and volumetric heat fluxes of 15 W/cm2 and 5 W/cm3 are achieved, along with reasonable pressure and pumping power requirements as well as accompanying acoustic noise. Obtained results yield a fivefold enhancement in heat removal capability compared to traditional forced air-cooling schemes View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Compact models for accurate thermal characterization of electronic parts

    Publication Year: 1997 , Page(s): 411 - 419
    Cited by:  Papers (30)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB)  

    This paper discusses several aspects regarding the derivation, accuracy, applicability, and possible future developments in the field of “compact models.” A “compact model” is a simplification of a full or detailed thermal model of an electronic package. As such, it consists of a simple network comprising a limited number of thermal resistances (typically 7), connecting the critical part of the device (usually the junction) to the outer parts of the device. Furthermore, the “compact model” is independent of the applied boundary conditions, and is an accurate representation of the full model. It is found that the compact models values typically approach the full model values within 6%. Compact models are suited for embedding in design environments in use by the electronics industries, because they can be incorporated into the component libraries linked to board and system level thermal analysis software packages View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Intermetallic compound layer development during the solid state thermal aging of 63Sn-37Pb solder/Au-Pt-Pd thick film couples

    Publication Year: 1997 , Page(s): 478 - 490
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB)  

    A study was performed which examined the solid state, intermetallic compound layer growth kinetics between 63Sn-37Pb solder and a 76Au-21Pt-3Pd (wt.%) thick film conductor on 96% alumina substrates. A linear, multivariable regression analysis was used to assess the experimental data according to the following empirical relationship: x-x0=Atn exp(-ΔH/RT). A time exponent of n=0.78±0.08 was observed, suggesting that a combination of bulk diffusion and interface reaction mechanisms were responsible for layer growth. The apparent activation energy, ΔH, was 106⩾8 kJ/mol. Parallel aging experiments were performed on diffusion couples fabricated between 63Sn-37Pb solder and bulk alloy stock having the same Au-Pt-Pd composition as the thick film. Similar growth kinetic parameters were computed. Intermetallic compound layer growth was accelerated under thermal cycling and thermal shock conditions due to residual stresses generated by the thermal expansion mismatch between the solder and the ceramic substrate View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Finite element simulation of the temperature cycling tests

    Publication Year: 1997 , Page(s): 530 - 536
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    Temperature cycling tests are commonly used in the semiconductor industry to determine the number of cycles to failure and to predict reliability of the solder joints in the surface mount technology packages. In this paper, the thermomechanical fatigue of Pb40/Sn60 solder joint in a leadless ceramic chip carrier package is studied and temperature cycling test is simulated by using a finite element procedure with the disturbed state concept (DSC) constitutive models. The progress of disturbance (damage) and the energy dissipated in the solder joint during thermal cycling are predicted. It is shown that the disturbance criterion used follows a similar path as the energy dissipation in the system. Moreover, the comparisons between the test data and the finite element analysis show that a finite element procedure using the DSC material models can be instrumental in reliability analysis and to predict the number of cycles to failure of a solder joint. Furthermore, the analysis gives a good picture of the progress of the failure mechanism and the disturbance in the solder joint View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fatigue crack propagation along polymer-metal interfaces in microelectronic packages

    Publication Year: 1997 , Page(s): 496 - 504
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    In this study, a fracture mechanics-based technique was used for characterizing fatigue crack propagation (FCP) at polymer-metal interfaces. Sandwich double-cantilever beam (DCB) specimens were fabricated using nickel and copper-coated copper substrates bonded with a thin layer of silica-filled polymer encapsulant. Under cyclic loading, crack propagation was found to occur at the polymer-metal interface. The interfacial failure mode was verified by scanning electron microscopy (SEM) analysis of the fatigue fracture surfaces. The crack growth rate was found to have a power-law dependence on the strain energy release rate range, and exhibited a crack growth threshold, much like the fatigue crack growth threshold stress intensity factor range for monolithic bulk metals, polymers, and ceramics. Interfacial FCP data for three candidate encapsulants predicted cracking resistances that were well correlated with package-level reliability tests. By varying the surface roughness of the copper and nickel plating, it was shown that interfacial FCP resistance increased with increasing roughness. The observed increases in FCP resistance were attributed to a reduction in the effective driving force for fatigue fracture along the rougher interfaces, and could be accounted for by a crack-deflection model View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Pressure loss modeling for surface mounted cuboid-shaped packages in channel flow

    Publication Year: 1997 , Page(s): 463 - 469
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB)  

    An analytical model is presented that predicts pressure loss for fully developed flow for air in a parallel plate channel with an array of uniformly-sized and spaced cuboid blocks on one wall. The model is intended for use in optimizing enclosure designs for air cooled electronics equipment containing arrays of printed circuit boards. Using a composite solution, based on the laminar and turbulent smooth wall channel limiting cases, the friction factor for periodic fully developed how can be calculated as a function of the array geometry and fluid velocity. The resulting model is applicable for a full range of Reynolds numbers, 1⩽ReDhˇ⩽100000 and accurately predicts the available measured values to within a 15% average difference View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the effect of nonlinear boundary conditions for heat conduction in diamond heat spreaders with temperature-dependent thermal conductivity

    Publication Year: 1997 , Page(s): 537 - 540
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB)  

    For steady-state heat conduction in diamond heat spreaders with temperature-dependent thermal conductivity, we examine the valid range of the commonly used approximate solution against a rigorous solution which we have recently formulated. The basic difference between our work and the approximate solution lies in the boundary condition (bc) of the transformed temperature over the spreader-sink interface-we use a nonlinear be whereas the bc in the approximate solution has been assumed to be linear. We point out that the valid range of the approximate solution is determined by the temperature difference above the ambient over the interface. The discrepancy between the two solutions becomes severe (>10%) for devices of radius around 50 μm involving high power dissipation (>20 W) View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The world of thermal characterization according to DELPHI-Part II: Experimental and numerical methods

    Publication Year: 1997 , Page(s): 392 - 398
    Cited by:  Papers (29)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB)  

    For pt.I see ibid., vol.20, no.4, pp.384-91 (1997). The purpose of the second part of the DELPHI survey paper is twofold. First, to describe the experimental methods that have been developed to validate the numerical models generated to characterize a certain electronic part in full detail and second, to highlight the various approaches that were studied to generate compact models from the detailed models. It can be concluded that the results of the experimental as well as the numerical methods which are highlighted in this part are characterized by a high accuracy, typically of the order of 95% or better View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Electro-thermo-mechanical responses of conductive adhesive materials

    Publication Year: 1997 , Page(s): 470 - 477
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    Micromechanics models which aim to provide an understanding of conductive adhesive materials from the level of micro-particles (less than 30 mm) are presented in this paper. The pressure-induced conducting mechanisms are investigated. A deformation analysis reveals a logarithmic pressure-resistance relationship and is capable of addressing the conducting phenomena for both rigid and deformable particle systems within a contact mechanics framework. This logarithmic relationship also provides analytical support for findings reported in the literature of conductive adhesive research. It is observed that electrical contacts are made by squashing conducting particles for a deformable particle system while the particle penetration creates a crater in metallization to make contacts for a rigid particle system. The current analysis provides simple closed-form solutions for the elastic deformation of single-particle contacts and based on the assumption that the contact forces are evenly distributed in a conductive film, the pressure-resistance responses are correlated to the particle volume fraction. The high volume fraction, while ensuring that there are a sufficient number of particles to make contacts, may limit the particle deformation due to overall increased stiffness, resulting in the increased resistance on a per particle basis. The current analysis also offers insight into design considerations whereby limited amount of deformation (low processing temperature) and sufficiently low electrical resistance are to be simultaneously satisfied. For the mechanical performance, the uniaxial nonlinear stress-strain relationship is obtained for conductive adhesive systems in terms of polymer and particle material properties. The Mori-Tanaka's method is utilized to account for particle-particle and particle-matrix interactions. The behaviour in thermal expansion within the elasto-plastic deformation range is also obtained in a similar fashion. In all these calculations, only a very simplified finite element analysis for the problem of a particle embedded into an infinitely extended matrix material needs to be carried out View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The effect of varying the Cu/Au ratio on the thermal-cycle fatigue life of 95/5 PbSn bumps

    Publication Year: 1997 , Page(s): 491 - 495
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    The MICRO SWITCH Division of Honeywell adopted the IBM C4 flip chip die attach method for its underhood automotive applications in the mid to late 1970's. There has been a gradual increase in the reliability of IC-ceramic solder joints. This experiment shows the effect of the interface metallurgy on the thermal-cycle fatigue life of C4 technology. Samples are manufactured using a standard industry technique first pioneered by IBM. Included are results from initial experimentation on post processed bump limiting metallurgy (BLM), and mechanical data on two different sizes of IC with the variation of gold thickness. Assemblies were exposed to a thermal-cycle temperature range of -40°C to 150°C. In the initial tests, half of each wafer is placed in 1/1 concentrated H2O2/Acetic to remove the PbSn bump and expose the BLM. The etched samples are SEM/EDS analyzed for interfacial constituents. A comparison of the interface morphologies and the thermal-cycle fatigue life are shown. These results show that for extended thermal-cycle life times (>1000) that the Cu thickness of 1.2 μm and an Au thickness of 0.08 μm which is reduced from the initial 0.15 μm of our standard process is optimal. This is due to the reduced Au incorporation in the copper-tin intermetallic which produces an increase in the fatigue life and strength of the joints View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Thermal characterization of chip packages-evolutionary development of compact models

    Publication Year: 1997 , Page(s): 399 - 410
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    The expanded Rjc methodology, first proposed in 1989, makes it possible to extend the use of this common figure-of-merit to chip packages with nonisothermal cases. This proposal spurred considerable debate and contributed to renewed efforts to provide “compact” thermal models of single chip packages, for preliminary design, as well as for detailed numerical simulation of populated printed circuit boards. This presentation offers a review of the development of this modified Rjc methodology and its efficacy in replicating the chip, or junction, temperature predicted by detailed numerical simulation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Design of circular heat spreaders on semi-infinite heat sinks in microelectronics device applications

    Publication Year: 1997 , Page(s): 452 - 457
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    Using the rigorous analytical solutions, we discuss design aspects in terms of thermal resistance and temperature uniformity for the canonical heat dissipation configuration consisting of a circular heat spreader on a semi-infinite heat sink. Regarding the optimized size of the heat spreader, we have found that the minimum temperature thickness of the spreader depends on the thermal conductivity values of the spreader and the sink, in contrast to the results published previously by other researchers. In addition, a new design formula d=0.44 b for the selection of spreader thickness d from the spreader radius b is proposed to replace the commonly used rule d=b/3. Our results have confirmed the design rule b=5 a for the selection of the spreader radius b from a given heat source radius a. To facilitate the complete design of the heat spreaders, we present two nomographs in the form of contour plots for the normalized thermal resistance and the normalized temperature uniformity View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Is the maximum acceleration an adequate criterion of the dynamic strength of a structural element in an electronic product?

    Publication Year: 1997 , Page(s): 513 - 517
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    The dynamic strength of structural elements of micro- and portable electronic products is often evaluated on the basis of the measured maximum acceleration which these elements experience during shock or drop tests. It is well known, however, that it is the dynamic stress, not the acceleration, which is a true criterion of the dynamic strength. Using examples of structural elements that can be idealized as a simply supported beam or a cantilever beam with a concentrated mass at the end, we show that for elements of the given geometry and weight, the level of the maximum stress can be indeed judged upon on the basis of the measured acceleration. However, the application of the measured acceleration as a criterion of the dynamic strength can be misleading if applied to elements of different dimensions, weight and materials. We conclude that although the maximum acceleration is substantially easier to measure, it is the maximum dynamic stress that should be evaluated experimentally or theoretically when there is a need to establish the level of the dynamic strength of a structural element of an electronic product and the role of different factors affecting this strength. The obtained information can be helpful when evaluating the results of, or designing drop tests for electronic products View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Pressure drop and heat transfer in an isothermal channel with impinging flow

    Publication Year: 1997 , Page(s): 458 - 462
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    The performance of air-cooled plate-fin heat sinks in impinging flow differs significantly from that of similar heat sinks in parallel flow. A numerical experiment and analytical scaling has been carried out to determine the pressure drop and thermal performance of single isothermal channels with variable-width impinging flow. The flow enters the channel normal to the heat sink base. The pressure drop and thermal performance of the flow in this configuration are particularly important for analyzing plate-fin heat sinks for which axial fans supply the flow, since the fan flow rate varies with the static pressure. The results of the numerical experiment and scaling are combined into dimensionless correlations for pressure loss coefficient and channel average Nusselt number. These correlations may then be used to predict the thermal performance of the heat sink View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Perspectives to understand risks in the electronic industry

    Publication Year: 1997 , Page(s): 542 - 547
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (60 KB)  

    The key perspectives that reveal sources of risk in the electronics industry have been identified. The needs of the low-volume industry are found to be very different than those of the volume-driven industry. An implication of these findings is that very different research programs are needed to empower each of these two sectors of the electronics industry, and strategic research programs are needed where academia, industry and government can collaborate to resolve many of these issues. The low-volume complex electronic systems (LVCES) industry needs research programs that focus primarily on the obsolescence, reliability and maintainability issues, while the volume-driven complex electronics products (VDCEP) industry needs research programs that focus more on the manufacturability, quality, and recurring cost issues. Systems engineers would do well to survey their own customer-base using the key perspectives presented here, as a template, to define their own life cycle risk issues View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Issues in validating package compact thermal models for natural convection cooled electronic systems

    Publication Year: 1997 , Page(s): 420 - 431
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    A methodology is proposed for the validation of compact thermal models of electronic packages which utilizes data and simulations obtained from a simple but realistic system containing the package. The test system used to demonstrate the methodology is the enclosure specified by the Electronic Industries Association JEDEC Subcommittee JC15.1 for thermal measurements in a natural convection environment. Simulations for a detailed model and several different compact models for a 88-pin plastic quad flat-package in the enclosure are in good agreement with experimental measurements of junction temperature. The study shows that the system must be well characterized, including accurate knowledge of circuit board thermal conductivity and accurate simulation of radiation heat transfer, to serve for validation purposes. For the package used in this study, system level considerations can outweigh package level considerations for predicting junction temperature. Given that the system is accurately modeled, the JEDEC enclosure can serve as a viable experimental validation tool for compact models View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Study of delaminated plastic packages by high temperature Moire and finite element method

    Publication Year: 1997 , Page(s): 505 - 512
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    In the current study, 1200 l/mm gratings are replicated at elevated temperatures onto the cross sections of two delaminated plastic packages: a thin quad flatpack plastic package (TQFPP) and a power small outline plastic package (PSOPP). The specimens are measured at room temperature for thermal deformation induced by cooling process. The finite element models are used to simulate the cooling process and the results are compared with the Moire interferometry results. The finite element models with different delaminations between die and die attach are used to simulate the fringe patterns obtained from Moire interferometry. It was found that the delamination size can be estimated by the combination of Moire technique and finite element method. The finite element model, once verified, can then be used in making cost effective decisions in plastic packaging design and processing View full abstract»

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

Aims & Scope

This Transaction ceased production in 1998. The current publication is titled IEEE Transactions on Components, Packaging, and Manufacturing Technology.

Full Aims & Scope