By Topic

IBM Journal of Research and Development

Issue 5 • Date Sept. 1993

Filter Results

Displaying Results 1 - 10 of 10
  • Preface

    Page(s): 582 - 583
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (185 KB)  

    Pin-in-hole technology (ceramic electronic-circuit-chip carriers with pins that are inserted into the plated through holes of epoxy-glass printed circuit cards) dominated IBM subsystem-assembly technology through the 1960s and 1970s. The 1980s saw the emergence of surface mount technology (SMT), peripherally leaded components mounted on the surface of printed circuit cards. SMT no longer required large plated through holes in the circuit cards to accommodate chip carriers with pins and thereby provided higher-efficiency packaging. In the 1990s the need for packages with higher and higher I/O counts is being driven by the increased circuit density of CMOS device technology. These 1/0 demands are driving peripherally leaded surface-mounted components to smaller pitches (lead-to-lead spacing), which in turn has decreased circuit card assembly yields through added process complexity, and has thus increased the overall device packaging cost. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Editor's note

    Page(s): 584
    Save to Project icon | PDF file iconPDF (59 KB)  
    Freely Available from IEEE
  • Finite element analysis for Solder Ball Connect (SBC) structural design optimization

    Page(s): 585 - 596
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1029 KB)  

    Solder Ball Connect (SBC) is a second-level surface mount electronics packaging technology in which ceramic modules containing one or more chips are joined to a circuit card (FR-4) by means of an array of nonhomogeneous solder columns. These columns consist of a high-temperature-melting 90%Pb/10%Sn solder sphere attached to the module and card with eutectic solder fillets. The solder structures accommodate the bulk of the strain (which is due to the thermal-expansion mismatch between FR-4 and the 9211 ceramic of the modules) generated during power cycling. If the solder structures are not properly designed, the thermal strain can be a source of premature fatigue failure. In this work, finite element analysis is used to characterize the plastic strains that develop in the SBC interconnection during thermal cycling. Since plastic strain is a dominant parameter that influences low-cycle fatigue, it is used as a basis of comparison for various structural alternatives. Designed experiment techniques are used to systematically evaluate the thermal strain sensitivity to structural variables. Results are used to identify an optimally reliable structure that is robust in terms of assembly-process variables. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Attachment of Solder Ball Connect (SBC) packages to circuit cards

    Page(s): 597 - 608
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1082 KB)  

    IBM has developed an assembly process to attach a new family of Solder Ball Connect (SBC) integrated circuit packages to glass/epoxy cards using surface mount technology (SMT). The process provides nearly perfect yields for the resulting solder ball joint structures and ensures reliability by controlling wear-out due to metallurgical fatigue. The package, card, and process parameters found to most strongly influence the assembly yield and reliability are summarized, and unique test hardware and analysis techniques are discussed. Process considerations, analytical techniques, and test methods described for SBC packages should apply to other ball grid array (BGA) packages. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Thermal modeling of the infrared reflow process for Solder Ball Connect (SBC)

    Page(s): 609 - 620
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1182 KB)  

    A thermal model of the infrared reflow process has been developed for an FR-4 card populated with an array of Solder Ball Connect (SBC) modules. The analysis of the three-dimensional, transient, finite element model accounts for radiative exchange within the infrared oven and for the heat conduction (nonisotropic) within the modules and card. Transient temperature profiles of selected points and three-dimensional temperature distributions at selected times are presented to describe the primary heat-transport mechanisms. Numerical predictions and empirical data indicate that the SBC modules are relatively isothermal throughout the infrared reflow process. Therefore, every solder ball within the array exhibits a nearly identical thermal profile. This result is fortunate, since the inner solder ball connections cannot be visually inspected. The influence of module spacing and the ability to improve the reflow process by use of a high-emissivity cap coating are demonstrated. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Thermal-mechanical strain characterization for printed wiring boards

    Page(s): 621 - 634
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1166 KB)  

    Multilayer printed wiring boards are widely used in electronic packaging assemblies. One critical reliability concern is the thermal-mechanical strains induced by temperature change. For example, the in-plane strain affects the thermal fatigue life of surface mount solder interconnections, while the out-of-plane strain affects the mechanical integrity of the plated-through holes of the printed wiring boards. For this paper, a systematic study of the thermal-mechanical strain of epoxy-glass printed wiring boards, below and above the glass transition temperatures of the epoxies, has been carried out. The study includes measurements of properties of basic constituent materials (epoxy, glass fabric, copper), of intermediate building blocks in the fabrication process, and of final products. The study has led to a quantitative engineering model that predicts the average in-plane thermal-mechanical strain for use in modeling surface mount components on a printed wiring board, as well as the average out-of-plane thermal-mechanical strain for determining plated-through-hole reliability in thermal shock processes. The model was verified by two experimental techniques (measurement by thermomechanical analyzer, and moiré interferometry) applied to two epoxy resins and three glass fabrics, with and without copper planes. For thermal shock below the glass transition temperatures of the epoxy resins, the in-plane and out-of-plane strains are described by a modified rule-of-mixtures theory and a biaxial plane stress model, respectively. For temperatures above the glass transition temperatures, the in-plane strains are governed by the copper and glass fabric, whereas the out-of-plane strains are dominated by the incompressible fluid behavior of the epoxy resins. The nonuniform pattern of thermal expansion in regions populated with plated-through holes was examined. The reliability of surface mount solder interconnections and plated-through holes is discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Solder Ball Connect (SBC) assemblies under thermal loading: I. Deformation measurement via moiré interferometry, and its interpretation

    Page(s): 635 - 648
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1433 KB)  

    Thermal deformations that result from mismatches of coefficients of thermal expansion (CTE) in Solder Ball Connect (SBC) assemblies were investigated. The CTE mismatches of the materials and the components in the package have both macro and micro effects on the strain distributions in the SBC interconnections. The geometry of the SBC joint also has a strong influence on the solder strains in the SBC package. An experimental technique with high sensitivity and resolution, moiré interferometry, was used to obtain whole-field displacements. Thermal strains in SBC packages, especially the strain concentrations in the SBC joints, were then determined from the displacement fields. The experimental results played an important role in failure analysis, structural design optimization, and finite element model verification in the IBM SBC program. The results also show that moiré interferometry is a very powerful and effective tool in experimental studies of electronic packaging. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Solder Ball Connect (SBC) assemblies under thermal loading: II. Strain analysis via image processing, and reliability considerations

    Page(s): 649 - 659
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1125 KB)  

    A novel approach to processing interferometric moiré images, called computational Fourier transform moiré, has been developed. The essential principle of this technique is to automatically calculate a whole-field strain from digitized images of interferometric moiré fringes using digital Fourier transform procedures. With the use of this technique, a whole-field strain distribution of a Solder Ball Connect (SBC) interconnection under thermal loading was obtained. The calculated strain field was then used to understand fatigue modes of SBC observed from an accelerated thermal cycling (ATC) test. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Recent publications by IBM authors

    Page(s): 661 - 674
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1200 KB)  

    The information listed here is supplied by the Institute for Scientific Information and other outside sources. Reprints of the papers may be obtained by writing directly to the first author cited. Information on books may be obtained by writing to the publisher. Journals and boob are listed alphabetically by title; papers are listed sequentially for each journal. View full abstract»

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

    Page(s): 675 - 676
    Save to Project icon | PDF file iconPDF (163 KB)  
    Freely Available from IEEE

Aims & Scope

The IBM Journal of Research and Development is a peer-reviewed technical journal, published bimonthly, which features the work of authors in the science, technology and engineering of information systems.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Clifford A. Pickover
IBM T. J. Watson Research Center