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IBM Journal of Research and Development

Issue 3 • Date May 1969

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Displaying Results 1 - 14 of 14
  • SLT Device Metallurgy and its Monolithic Extension

    Page(s): 226 - 238
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1001 KB)  

    The glass-passivated, face-down semiconductor chip joining technology employed in IBM's SLT (Solid Logic Technology), has become not only a fundamental element in the hybrid circuitry of System/360 but also the basis for later metallurgical designs. The “flip-chip,” copper ball terminal, solder reflow technique is comprehensively reviewed and a discussion is given of its extension, through the use of ductile, all-solder terminals, to monolithic applications. View full abstract»

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  • Controlled Collapse Reflow Chip Joining

    Page(s): 239 - 250
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (753 KB)  

    Solder reflow connection of semiconductor devices to substrates has been shown to be a reliable, effective, and readily automated technique. Rigid copper spheres, which remain rigid during solder reflow, have been used successfully for some time as a major element of the contact joint. However, to expand the capability of such joints to larger devices such as multiple-transistor chips in hybrid components, ductile metallic joining pads can be used on the devices instead of the copper spheres to reduce mechanical strains and permit multi-pad devices to make proper contact to module lands during reflow. This paper describes a technique that prevents these solder pads from collapsing and permits large scale production. Termed “controlled collapse,” the method is based on limiting the solderable area of the substrate lands and chip contact terminals so that surface tension in the molten pad and land solder supports the device until the joint solidifies. The result is a sturdy, testable connection of high reliability (bond strength 30–50 gm, pilot-production yields exceeding 97%, predicted failure rate—based on laboratory tests—considerably lower than that of copper ball contacts). The process is economically adaptable to automation and offers considerable latitude in fabrication and control tolerances. View full abstract»

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  • Geometric Optimization of Controlled Collapse Interconnections

    Page(s): 251 - 265
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (887 KB)  

    This paper deals with the mechanical reliability of controlled collapse solder joints in modules subjected to the thermal fatigue conditions of machine usage. Particular emphasis is placed on design variability and how the shape and dimensions of the joint and chip affect reliability. A systematic technique is presented to optimize pad dimensions. A new experimental method to characterize chip-to-substrate interconnections—the torque test—is described and analyzed. Its applicability to design evaluation is discussed and representative data are analyzed. The relationship between torque test measurements and fatigue is discussed. View full abstract»

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  • Reliability of Controlled Collapse Interconnections

    Page(s): 266 - 271
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (446 KB)  

    The use of solder pads to join multi-pad integrated circuit chips to modules provides a highly reliable, rugged interconnection technology. This paper reports some important aspects of the reliability evaluation that was carried out on the “controlled chip collapse” interconnection system developed by IBM. Included are an analysis of the mechanics of the system, a model to establish the relationship among different thermal fatigue testing conditions, and experimental verification of the model. In the course of this work, the chip failure rate of the interconnection as used in present designs was predicted to be better than 10−7%/1000 hours for the mechanism studied. View full abstract»

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  • Parametric Study of Temperature Profiles in Chips Joined by Controlled Collapse Techniques

    Page(s): 272 - 285
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1037 KB)  

    Parameters governing the temperature profiles of typical semiconductor chips joined to circuit module substrates by controlled chip collapse (flip-chip bonding) techniques are discussed. These include the physical and geometric properties of various layers of metals and non-metals that form the chip-to-substrate interconnection. The importance of the bond between the interconnection and the substrate from the point of view of interfacial thermal resistance is indicated. Also, the “thermal pinch” effects of voids in controlled chip collapse interconnections are discussed. The various thermal impedances as obtained from computer simulated temperature profiles are given graphically as functions of the parameters. The derivation of a semi-empirical expression for predicting the transient response of junctions on joined chips is shown. View full abstract»

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  • Studies of the SLT Chip Terminal Metallurgy

    Page(s): 286 - 296
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1574 KB)  

    The thin film metallurgy used for SLT chip terminal contacts has been studied with respect to the soldering procedure used for chip-to-module joining. A simple solder immersion test was used to study wetting and dewetting effects on Cr films overlaid with films of Cu and other metals. It was found that the initial soldering reaction (consisting of the conversion of the Cu film to a Cu-Sn metallic layer) proceeds to completion in only a few seconds. Thereafter, the intermetallic layer starts to disintegrate and become thinner by a mechanism identified as solution-assisted spalling. Removal of the intermetallic layer by this mechanism is not limited by simple solubility considerations. From metallographic observations and the inability to produce direct wetting of Cr films by solder, it was concluded that the basic cause of solder dewetting is the excessive loss of intermetallic from the underlying Cr film. Dewetting is accelerated if the Cu film is deposited on an oxidized Cr surface. These observations underscore the importance of the manufacturing practice of overlapping the Cr and Cu depositions so as to obtain an adherent and interlocked structure which is resistant to spalling. Other studies have show that Al films are relatively inert to molten pure Pb-5% Sn solder, but are susceptible to rapid attack if gold is added to the solder. Appreciable delay of such attack is afforded by an overlying film of Cr, provided both surface and edge coverage are achieved. View full abstract»

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  • Parallel Methods for Approximating the Root of a Function

    Page(s): 297 - 301
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    We present a class of methods for approximating the root of a function. The methods are designed for execution on a parallel processor and when they are so executed, the speed of the approximation process is increased. The increase in speed is estimated analytically by computations of the order of convergence of the various methods presented. View full abstract»

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  • Scattering of Electromagnetic Radiation by a Large, Absorbing Sphere

    Page(s): 302 - 313
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1045 KB)  

    Details are provided for two subroutines with which one can compute the various characteristics of the electromagnetic radiation scattered by an absorbing, homogeneous sphere of any reasonable size. The necessary expressions for this purpose were first derived by Mie. The method of computations used is the so-called method of logarithmic derivative of one of the complex functions, introduced by Infeld. The main difference between the two subroutines is in the procedure used in computations of one of the functions. This function is computed by an upward recurrence procedure in one subroutine and by a downward recurrence procedure in the other. Sufficient results for demonstrating the reliability of these programs are presented and discussed for a sphere of 10 µm radius illuminated by an unpolarized radiation of 0.4 µm wavelength. View full abstract»

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  • A General Method for Obtaining Impedance and Coupling Characteristics of Practical Microstrip and Triplate Transmission Line Configurations

    Page(s): 314 - 322
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (767 KB)  

    In order to design an interconnection system for nanosecond-risetime logic circuitry, it is necessary to obtain a balance between impedance variations, propagation velocities, and crosstalk levels so as to achieve the best system speed as well as system speed control. To accomplish this, it is necessary to relate the electrical material properties and physical dimensions of the connections to characteristic impedances, propagation velocities, and crosstalk coupling coefficients. View full abstract»

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  • Thermal Expansion in a Constrained Elastic Cylinder

    Page(s): 323 - 330
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (726 KB)  

    The stress developed in an elastic cylinder of finite length undergoing thermal expansion with one end clamped is expressed in terms of a series expansion of a biharmonic function, appropriate derivatives of which give the displacements and stresses within the cylinder. The coefficients in this series are determined by a least-squares fit to the boundary conditions at the ends of the cylinder and values of the stress on various surfaces are found as functions of the height-to-radius ratio. All components of the stress tensor become infinite at the circumference on the clamped end. A tabulation is included of quantities of interest in any cylindrical problem in which the curved surface is a free surface. View full abstract»

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  • Recent Papers by IBM Authors

    Page(s): 331 - 334
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (501 KB)  

    Reprints of the papers listed here may usually be obtained most efficiently by writing directly to the authors. The authors' IBM divisions and locations are identified as follows: ASDD is the Advanced Systems Development Division; CD, Components Division; DPD, Data Processing Division; FSD, Federal Systems Division; RES, Research Division; SDD, Systems Development Division and SMD, Systems Manufacturing Division. East Fishkill, Endicott, Kingston, Owego, Poughkeepsie, White Plains, and Yorktown Heights are in New York; Los Gatos, Palo Alto, and San Jose, California; Gaithersburg, Maryland; Cambridge, Massachusetts; Rochester, Minnesota; Huntsville, Alabama; Burlington, Vermont; Raleigh and Research Triangle Park, North Carolina; Boulder, Colorado; Vienna, Austria and Boeblingen, Germany. Journals. View full abstract»

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  • Patents Recently Issued to IBM Inventors

    Page(s): 335 - 336
    Save to Project icon | PDF file iconPDF (344 KB)  
    Freely Available from IEEE
  • Authors

    Page(s): 337 - 338
    Save to Project icon | PDF file iconPDF (371 KB)  
    Freely Available from IEEE
  • Contents of previous two issues

    Page(s): 339
    Save to Project icon | PDF file iconPDF (159 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.

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