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Parts, Hybrids, and Packaging, IEEE Transactions on

Issue 3 • Date September 1975

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Displaying Results 1 - 15 of 15
  • Who's Who in G-PHP

    Page(s): 170
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  • Foreword

    Page(s): 171
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    Summary form only given, as follows. This issue of the IEEE Transactions on Parts, Hybrids, and Packaging is the fourth annual issue that will be devoted to papers that have been selected from those presented at the 1975 Electronic Components Conference. The Conference is sponsored by the Parts, Hybrids, and Packaging Group and by the Electronic Industries Association. It is held each May and took place this year on May 12-14 in Washington, DC, USA. The papers included in this issue have been selected on the basis of recommendations from the Conference Program Committee and from other reviewers. We are grateful to the reviewers and to the authors fer their cooperation and assistance in the preparation of this issue. The papers in this issue of the Transactions reflect the broad areas of interest to the PHP and the ECC, with the majority dealing with some aspect of the hybrid circuit technology. The first paper by Bulger develops a model that relates end of life drift to the extent of laser trimming on tantalum nitride thin film material. The second paper by Davy is an evaluation of existing leak detection standards and proposes and evaluates alternate leak detection techniques. The third paper by Reiss describes a thin film reactively bonded gold alloy which is compatible with most thick film materials including dielectrics, resistors, and conductors. The fourth paper, by Kinser et at., discusses the relationship between the failure rate of ceramic chip capacitors mounted on alumina substrates and the mounting technique used in bonding the capacitors. The fifth paper, by Hallet at., is an analysis of the reason for decreased strength of gold-plated copper leads on thin film circuits when aged at 200-300°C. The sixth paper by Jellison is a quantitive study of the effects of contamination of thermo compression ball bonding of gold to gold metallization. Papers seven and eight, by Van Horn and Antler, are concerned with connecting devices and the search for a- ternate materials. The ninth paper by Moody describes a new method of loading small current transformers used for current measurements under pulsed or high frequency conditions. The tenth paper, by Domingos and Wunsch is a study of the power required to cause failure in discmte resistors as a function of pulse width. View full abstract»

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  • Calculations for Leak Rates of Hermetic Packages

    Page(s): 177 - 189
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    An analysis is presented of the dependence of leak rates on geometry and flow mechanism. A combined-flow equation, valid for viscous, molecular, and diffusional flow is applied to capillary leaks and the results are extended to crack-shaped leaks and orifices. It is shown that for a given leak rate the geometry with the largest viscous contribution to flow is a single long capillary. A distinction is drawn between the rate at which a package leaks during helium leak test (in vacuum) and during use (in air at one atm pressure), and it is shown that the latter may be orders of magnitude smaller than the former because of the viscous contribution to flow during test and during bombing. Two different test procedures are proposed that are designed to prevent viscous flow by avoiding differences in total pressure: one is a one-atm "bath" instead of a "bomb" in radiotracer 85Kr, the other a gas-chromatographic collection of inert halogen-bearing gas that leaks out of a prefilled package. Both are predicted to give test leak rates within a factor of two of the use leak rates. Because of its widespread use and its complexity, the Howl and Mann molecular-flow equation is examined and a number of simplifying approximations are made to allow greater ease in its use. The time rate of change of pressure in a package is calculated using the simplifying approximation that leak rate is proportional only to difference in total or partial pressure, and the concept of maximum allowable dwell time for the "marginal gross leaker" is developed. Based on calculations of the rates of depressurization of a pressurized package, and of the rate of moisture accumulation in an unpressurized one, maximum allowable use leak rates RUfor a package of volume V, much lower than the currently used test leak rates, are proposed: Ru/Vleq10-9atm sec-1for pressurized packages or Ru/Vleq10-10for unpressurized ones. It is recognized that for most package volumes these levels are difficult to attain, but it is proposed that' less stringent limits fail in their intended purpose of guaranteeing hermeticity for a reasonable package life. View full abstract»

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  • Reactively Bonded Thin-Film Conductors, a New Component for Combination Thin- and Thick-Film Technology

    Page(s): 190 - 194
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    A 'thin-film reactively bonded gold alloy has been developed. This material is similar in composition and physical properties to thick-film reactively bonded golds. It is a vacuum-deposited material that is fired in air at high temperatures (1000°C) to form a strong bond with ceramic substrates. Thin-film reactively bonded gold is a dense, smooth rhaterial with high electrical conductivity. This alloy can withstand repeated firings in the 850 to 1000° temperature range and is compatible with most thick-film materials including dielectrics, resistors and conductors. It can be ,easily etched into fine geometrics (very high yield with one-mil line and one-mil spaces), making it a good candidate for high density interconnect technology. View full abstract»

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  • A Multicoat Non-Burnable Protection System for Electrical Elements

    Page(s): 235 - 238
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    An approach to the problem of the non-ignitable and moisture resistant protective coating for electrical elements that use a double layer of coating composed of two different materials was investigated. The two materials are different in terms of the protection which they provide to the element. The first coating is truly non-burnable, inert, and is permeable to moisture, while the second coating is burnable and is nonpermeable to moisture. The important feature of the multicoat system introduced here is the particular effect of the burnable layer on the ignitability of the system. It has been experimentally demonstrated that as the thickness of either layer is increased, the ignitability of the system decreases. The system may be designed such that no flame appears on the surface of the assembly under any conditions and yet the electrical element is well protected against moisture. View full abstract»

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  • Effect of Surface Contamination on the Thermocompression Bondability of Gold

    Page(s): 206 - 211
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    The recent development of a microshear test has made possible the quantitative study of the effect of surface contamination on thermocompression ball bonding of gold to gold metallization. Contarninant films were characterized by Auger electron spectroscopy and low energy ion spectroscopy. The thermocompression gold bonding process was found to be highly temperature dependent when organic films, which are barriers to metallic bonding, are present. Much of this temperature dependence could.be eliminated by rernoving the contaminant films by uV radiation prior to thermocompression bonding. Post-heat treatment resulted in the growth of metallic bond inter'faces, presumably by sintering mechanisms. View full abstract»

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  • Connecting Devices for Electronic Systems-Some General Design Considerations

    Page(s): 212 - 215
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    The use of Rent's rule in assessing the economic trade-offs in partitioning electronic systems into larger or smaller units is described. The impact of this assessment on the size and number of connectors required is presented, The roles of non-separable (splicing) and separable (plug.in) connectors are discussed. A qualification procedure to assure reliability of non-separable connectors and current design practices to assure reliability of separable connectors are reviewed. View full abstract»

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  • The Effect of Heat Treatment on the Resistivity of Polycrystalline Silicon Films

    Page(s): 239 - 240
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    The resistivity of doped polycrystalline silicon films has been studied as a function of post deposition heat treatments in an oxidizing atmosphere. It was found that a short oxidation cycle may produce a resistivity increase as large as three orders of magnitude in the polycrystalline films. The extent of change was dependent on the initial resistivity and the films' doping level and was independent of the total oxidation time. View full abstract»

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  • Gold Connector Contacts: Developments in the Search for Alternate Materials

    Page(s): 216 - 220
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    The characteristics of electroplated and wrought gold-based contact materials for high reliability connectors in low energy circuit applications are reviewed. To insure that contacts do not degrade by film formation due to corrosion, diffusion, or wear processes, certain practices have evolved on the compositions, 'thicknesses, porosities, hardnesses and manufacturing methods for the golds, and for underplatings that are used with them. Recently, however, its escalating cost has stimulated intensive work which shows that the thickness of gold required for satisfactory performance can often be reduced. In addition, manufacturing techniques which selectively locate gold to the, mating area of a contact have come into vogue. Other routes to cost reduction include the use of nonnoble materials, palladium, or golds alloyed with large amounts of base metals. View full abstract»

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  • Stability Analysis of Laser Trimmed Thin Film Resistors

    Page(s): 172 - 177
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    Laser trimmed tantalum nitride thin film resistors age at a greater rate than untrimmed films. The high energy required to vaporize material in the cut, or' kerf, modifies the aging characteristics of film contiguous to the kerf. This undesirable feature could be mitigated if a design procedure were available to assure that end of life tolerances were manageable. In this paper a r. model is developed that relates end of life drift to the extent of laser machining. Experimental! data are used to obtain an aging model for material near the kerf and that parallel portion which is. more remote. It is found that precise definition for the boundary between these areas is not essential to complete characterization of the composite. The result is a graphical design procedure 'that assures laser trimmed resistors will meet end of life tolerance specifications. The analysis was extended to determine the position of "L' cuts in bar resistors yielding optimum lifetime stability. It was found that trimming with an 'L' cut at the mid point of the resistor results in acceptably small deviations from maximum stability. View full abstract»

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  • The Relationship Between Reliability and Bonding Techniques in Hybrid Systems

    Page(s): 195 - 201
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    Differential thermal expansion has been shown to be responsible for many observed failures in ceramic chip capacitors mounted on alumina substrates. The present work has shown that the mounting techniques used in bonding the capacitors have a marked effect upon the thermally induced mechanical stress and thus the failure rate. A mathematical analysis of a composite model of the capacitor-substrate system to predict the magnitude of thermally induced stresses have been conducted. It has been experimentally observed that the stresses in more compliant bonding systems such as soft lead/tin and indium solders are significantly lower than those in hard solder and epoxy systems. The marked dependence upon heating and cooling rate has proven to be a determining factor in the prediction of failure n both the indium and tin/lead solder systems. This study has shown that the harder or higher melting solders are less susceptible to thermal cycling effects but that they are more likely to fail during initial processing operations, in the course of the study, strain gage techniques were used to determine thermally induced expansion stresses of both the capacitors and the alumina substrates. Thus, the compliance of the different bonding mediums were determined. From the data obtained, several recommendations are made concerning the optimum bonding system for the achievement of maximum reliability. View full abstract»

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  • High Pulse Power Failure of Discrete Resistors

    Page(s): 225 - 229
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    Theoretical and experimental studies have been conducted on discrete resistors to determine the; power required to cause failure as a function of pulse width over the range 1µs to 10 ms. Single pulses of increasing amplitude were applied until voltage breakdown occurred, the resistor shattered, or until a resistance change of 5% or more took place. Carbon composition (both slug and film type), wire-wound (both precision and power type) and film resistors were tested. Computer calculations, temperature cycling test,% and field plots were utilized to interpret the results. View full abstract»

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  • Scanning Micro-Spot Auger Spectroscopy Study of Interdiffusion and Eutectic Formation in W-Pt-W-Au Thin Films

    Page(s): 229 - 235
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    Reactions in rf sputtered W-Pt-W-A,u films on oxidized and unoxidized Si substrates have been analyzed using a micro-spot scanning Auger spectroscopy and microscopy technique. The analysis shows that the W-Pt-W-Au films on Si substrates have undergone three annealing stages resulting in gold-silicon eutectic formation and migration. Stage I (450°C, 12 hours) was characterized by the formation of Si rich globular regions on the Au film. During Stag,,, II (450°C, 24 hours) the entire unreacted gold film was consumed. Finally, during Stage III (550°C, 24 hourS) gold and the liquid phase eutectic migrated toward the metal-Si interface. For W-Pt-W-Au on oxidized Si substrates, the diffusion barrier of W-Pt-W was observed to be effective up to 550°C tot 24 hours. View full abstract»

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  • Strength of Gold-Plated Copper Leads on Thin Film Circuits Under Accelerated Aging

    Page(s): 202 - 205
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    The strengths of thermocompression bonds made between gold plated copper lead frames and gold metallized thin film circuits decrease in time when aged at 200-300°C in air or vacuum unless there is a diffusion barrier (such as nickel) between the copper and gold. After pulling bonds to destruction, failure modes and failed surfaces were characterized by scanning electron microscopy, Auger spectroscopy, electron microprobe, stylus probe, and X-ray diffraction. The failed surface on the substrate side of the bond was very rough, appearing to consist of "mountains" of almost pure Cu resting on a relatively smooth layer of grains, identified as Cu3Au, where the Cu3Au regions were Visible in the valleys between the copper mountains. The mating failed surface on the lead side of the bond was similarly rough, but with only a few scattered grains of Cu3Au evidently pulled out from the opposite surface. Oxidation, pore formation (Kirkendall effect), and ordered phase formation were considered as possible mechanisms for the degradation. Oxidation was ruled out by the observation that bonds degraded as fast in vacuum as in air. Ordered phase formation was judged more likely than pore formation as the primary mechanism. A parameter,tau, to describe the time required for measurable degradation was defined as the time for the average 90° peel strength of a 0.25 X 0.75 mm lead to decrease from six or seven pounds to four pounds. This parameter was found to be temperature activated with an activation energy of 0.8 eV. Since ordering and pore formation are both dominated by interdiffusion,tauwas extrapolated to lower temperatures using the diffusion coefficient measurements of Pinnel and Bennett, resulting in a value of ten years at 50°C. However, with a 5000Å ± 2500Å nickel diffusion barrier between the copper lead and the gold plate, the value oftauextrapolated to 50°C was considerably greater than 40 years, as desired in Bell System equipment. View full abstract»

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  • A New Method for Current Transformer Loading

    Page(s): 221 - 225
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    The concept of using separate load and output windings on small current transformers offers properties which may be useful in many applications. The principle feature of this method is that the resistance of the load winding itself serves as the entire load for the device. Several means of achieving such a configuration are suggested, including the use of bifilar windings and single-turn load windings made with bare wire or conductive coatings placed directly on the core. Desirable features of this method include economy of size and shape, and performance suitable for many applications. Limitations of performance exist for higher frequency conditions, but a considerable range of use is still available to the user. View full abstract»

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Aims & Scope

This Transaction ceased production in 1977. The current publication is titled IEEE Transactions on Components, Packaging, and Manufacturing Technology.

Full Aims & Scope