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IBM Journal of Research and Development

Issue 6 • Date Nov. 1984

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Displaying Results 1 - 16 of 16
  • Preface: Advances in materials and processes for printed circuit packaging technology

    Page(s): 652 - 654
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    The basic set of sciencesr elated to printed circuit board production includes almost all of the basic disciplines of the materials scientist. This is well illustrated here in a set of papers encompassing studies in materials characterization, analytical chemistry, polymer chemistry, electrochemical reactions, surface phenomena, diffusion and permeation, mechanics, and metallurgy View full abstract»

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  • Moisture solubility and diffusion in epoxy and epoxy-glass composites

    Page(s): 655 - 661
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (624 KB)  

    The solubility and kinetics of moisture transport mechanisms in epoxy-type resin and resin-glass composites have been investigated over a range of partial pressure and temperature. Moisture absorption-desorption in these systems is a quasi-reversible process, the kinetics of which are non-Fickian (Type II) and dependent on prior history. The multistaged sorption and transport behavior are interpreted in terms of multiphase models. View full abstract»

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  • Bending-cantilever method for the study of moisture swelling in polymers

    Page(s): 662 - 667
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    Self-induced bending of a bilayer strip is shown to be a simple but sensitive method for the study of water absorption and swelling in polymers. Expressions for both the time-dependent and equilibrium curvature of the strip have been derived, enabling both diffusional and dilatational parameters to be extracted from experimental data. To illustrate the technique, it is shown that a vacuum-dried epoxy swells linearly with water content, at a rate of 0.93% in volume per weight percent of water. Desorption into vacuum has been observed under diffusion-controlled conditions and the diffusion coefficient for water in the epoxy found to be 2.5×10−9 cm2/s at 295 K. View full abstract»

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  • Mechanisms of electroless metal plating: I. Mixed potential theory and the interdependence of partial reactions

    Page(s): 668 - 678
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (985 KB)  

    Electroless plating reactions are classified according to four overall reaction schemes in which each partial reaction is either under diffusion control or electrochemical control. The theory of a technique, based on the observation of the mixed potential as a function of agitation, concentration of the reducing agent, and concentration of metal ions, is presented. By using this technique it is shown that in electroless copper plating the copper deposition reaction is diffusion-controlled, while the formaldehyde decomposition reaction is activation-controlled. Values of the kinetic and mechanistic parameters for the partial reactions obtained by this method and by other electrochemical methods indicate that the two partial reactions are not independent of each other. View full abstract»

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  • Mechanisms of electroless metal plating: II. Decomposition of formaldehyde

    Page(s): 679 - 689
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (822 KB)  

    A detailed investigation of the decomposition of formaldehyde was carried out to account for the fact that formaldehyde decomposition on Group VIII metals, e.g., Pd, occurs without simultaneous hydrogen generation, while on Group IB metals, e.g., Cu, formaldehyde decomposition is accompanied by hydrogen evolution. It was found that in principle metals may be divided into three main classes: (a) metals with positive free energy of hydrogen adsorption, (b) metals with free energy of hydrogen adsorption close to zero, and (c) metals with negative free energy of hydrogen adsorption. In the case of class (a) metals formaldehyde oxidation is accompanied by hydrogen evolution; for class (b) metals there is no simultaneous hydrogen evolution; and class (c) metals show low catalytic activity for formaldehyde oxidation. Hence, formaldehyde cannot be used as a reducing agent for electroless plating of class (c) metals. View full abstract»

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  • Initiation of electroless Cu plating on nonmetallic surfaces

    Page(s): 690 - 696
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (666 KB)  

    Electroless plating of a metal on a dielectric substrate requires the prior deposition of a catalyst such as a Pd-Sn colloid consisting of a metallic Pd core surrounded by a stabilizing layer of Sn ions. The activation step (deposition of the colloid) is usually followed by an acceleration step (removal of excess ionic tin). Adhesion of the deposit to the substrate is improved by mechanical and chemical pretreatment steps. An electrochemical method has been developed for assessing the catalytic activity of Pd-Sn colloids. Hydrogen sorption in the Pd in the colloid can be correlated with catalytic activity, since Pd accessible for the H-sorption reaction is also accessible as the catalyst for the electroless deposition reaction. These conclusions have been confirmed by surface analytical techniques and by functional tests. The efficacy of various accelerating solutions has also been assessed. View full abstract»

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  • Microstructure evolution during electroless copper deposition

    Page(s): 697 - 710
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1373 KB)  

    A study using transmission and scanning electron microscopy was made of the evolution of the microstructure of electroless plated Cu on activated amorphous substrates and on single-crystal Cu grains. On amorphous substrates activated in a PdCl2-SnCl2 colloidal solution, Sn atoms dissolved into the plating solution concurrently with Cu deposition on the substrate during the initial stage of deposition. The very small face-centered-cubic grains of Cu-Pd solid solution agglomerated into much larger particles and later coalesced into spherical grains. As the grains grew, they developed crystallographic facets, impinged upon one another, and finally covered the entire substrate. Grains of energetically favorable crystallographic orientation selectively developed into the columnar structure. These columnar grains contained subgrains, dislocations, and twins. Remarkably different structures were observed for the Cu grown on large single-crystal grains. In this case epitaxial growth dominated the plating process. Low-surface-energy (111) Cu planes were frequently observed on plated Cu surfaces. Growth rates were a function of substrate orientation. View full abstract»

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  • Micromechanics of multilayer printed circuit boards

    Page(s): 711 - 718
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (619 KB)  

    Analytical and experimental techniques are reported for the evaluation of micromechanical components in multilayer printed circuit boards. The concern in this investigation comes from the Z-axis thermal mismatch between epoxy-glass and copper that generates stresses when the board is subject to a temperature change. Finite-element modeling for both plated through-holes (PTH) and buried via (PV) structures is used to calculate the stresses in the copper barrel and at the via junctions. A simple experiment is designed to measure the thermomechanical strain in the PTH barrel. Also discussed are the PTH peel and PV pull techniques which have been used to characterize the barrel-laminate adhesion and the via junction strength. View full abstract»

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  • Optimization of interconnections between packaging levels

    Page(s): 719 - 725
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (583 KB)  

    In large-scale integrated circuits, the interface between ceramic modules and the next level—epoxy-glass circuit boards or cards—contains a large number of pin arrays. Because the modules and the card are usually quite rigid and mechanically strong, the interface between the module and the card is commonly the weakest region in the assembly system. This interface is where the differential deformations between the two levels of packaging are accommodated. This paper describes a theoretical and experimental program to understand the loadings and stresses present, and to optimize the design of the connecting pin in order to distribute the stresses more evenly across the surfaces of the braze joint that connects the pin to the ceramic module. This work was done jointly by members of the East Fishkill and Endicott laboratories. View full abstract»

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  • Immersion tin: Its chemistry, metallurgy, and application in electronic packaging technology

    Page(s): 726 - 734
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    The surfaces in copper-plated through-holes in printed circuit boards for complex electronic packaging can be made solderable by immersion deposition of tin. The properties of the prepared surfaces vary from those of “white immersion tin,” which is easily wetted by molten tin solder, to those of “gray immersion tin,” which is nearly nonwettable. The wettability affects the electrical contact between the printed circuit board and the modules on it. In this paper, the rate law for tin deposition in the tin immersion plating bath is studied. Certain effects of chemical composition of the plating bath upon the character of the tin layer are investigated and the effects of thermal annealing of the plated surface upon the composition of the tin layer are determined. The differences in composition of white and gray immersion tin surface coatings are revealed by X-ray diffraction Rutherford backscattering spectroscopy and Auger electron spectroscopy. Solderability tests on Sn, Cu, Cu3Sn, and immersion tin surfaces are included. View full abstract»

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  • High-temperature stability of a polyimide film

    Page(s): 735 - 740
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (451 KB)  

    Polyimide (PMDA-ODA) films were analyzed by mass spectroscopy to determine their high-temperature stability. Using a high-resolution instrument, the identity of the low-molecular-weight evolved gases was confirmed. With a semiquantitative technique, the effect of a vacuum pre-bake was shown to reduce outgassing appreciably during subsequent treatment at high temperature. Subjection of the films to moisture did not affect their thermal stability. Low-temperature processing (240°C vs 400°C) reduced gaseous evolution by an order of magnitude. View full abstract»

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  • Determination of Gafac in complex solution matrices

    Page(s): 741 - 747
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    A new analytic method is described for determining the concentration of Gafac Re-610 (trademark of the GAF Corporation, New York, NY) in multicomponent solutions. This method utilizes a simple methylene chloride extraction to separate the Gafac from interfering chemical species, such as cupric sulfate. The ultraviolet absorbance of the methylene chloride extract is then measured at 276 nm and is shown to be proportional to the concentration of Gafac over the range of 1–170 ppm. However, this relationship is nonlinear except for concentrations less than 15 ppm. The limit of detection is 0.6 ppm and the relative precision at the 10-ppm level is ±6%. Experiments to optimize and characterize various aspects of the analytical procedure are described, including determining the absorptivity of Gafac, measuring the distribution ratio, calculating extraction efficiencies, optimizing the extraction pH, and evaluating selected spectral interferences. View full abstract»

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  • Recent papers by IBM authors

    Page(s): 748 - 756
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (693 KB)  

    Reprints of the papers listed here may usually be obtained by writing directly to the authors. The authors' IBM divisions or groups are identified as follows: CHQ is Corporate Headquarters; CPD Communication Products Division; DSD, Data Systems Division: ESD, Entry SystemsD ivision: FED, Field Engineering Division; FSD, Federal Systems Division; GPD, General Products Division: GTD, General Technology Division; IPD, Information Products Division; ISG, Information Systems Group; IS&CG, Information Systems & Communrcations Group; IS&TG, Information Systems & Technology Group; NAD, National Accounts Division; NMD, National Marketing Division; RES, Research Division; SPD, System Products Division; SRI, Systems Research Institute; and STD, Systems Technology Division. Papers are listed alphabetically by authors. View full abstract»

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  • Recent IBM patents

    Page(s): 757 - 760
    Save to Project icon | PDF file iconPDF (274 KB)  
    Freely Available from IEEE
  • Author Index for papers in Volume 28

    Page(s): 761 - 764
    Save to Project icon | PDF file iconPDF (239 KB)  
    Freely Available from IEEE
  • Subject Index for papers in Volume 28

    Page(s): 765 - 768
    Save to Project icon | PDF file iconPDF (276 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