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Components, Hybrids, and Manufacturing Technology, IEEE Transactions on

Issue 3 • Date Sep 1985

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Displaying Results 1 - 14 of 14
  • A New Scheme for Device Packaging

    Page(s): 309 - 312
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    A new method for forming low resistivity conductors in a doped polymer film has been used in a novel device packaging scheme. In a first application, the focused output of a laser is used to write silver connections between device bonding pads and package conductors to fabricate a working clock. View full abstract»

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  • Steady-State Computer Simulations of Package Sealing Methods

    Page(s): 333 - 342
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    A two-dimensional computer model of a 0.300 inch side braze package is developed. The steady-state energy equation is solved using the finite difference method. Nonlinear radiation, convection, and conductivity terms are handled using an iterative approach. The computer model is used to simulate hermetic package sealing by the selective placement of heat sources and heat sinks. The sealing methods include hot capping, resistance heating, and seam soldering. The results are experimentally verified using a specialized hot capping fixture and the temperature sensitive parameter (TSP) method. It is found that conduction is the dominant form of heat transfer to the package die. Thermal contact resistance between the package base and the heat sink has the greatest effect on the die temperature. Package construction and material are also important. For a source temperature of 454°C and a sink temperature of 24°C, the die temperature was found to vary between 36°C and 93°C, depending on the sealing conditions. View full abstract»

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  • Solder Joint Behavior in HCC/PWB Interconnections

    Page(s): 391 - 396
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    The majority of effort to improve the reliability of surface mounted hermetic chip carrier to printed wiring board (HCC/PWB) interconneetions has been directed toward developing a PWB with a coefficient of thermal expansion (CTE) matched to the ceramic chip carrier. This approach has been demonstrated as an effective means of reducing stress in the solder joints that occurs during thermal cycling and, therefore, has significantly improved the reliability of these systems. Honeywell's program in this area compared the reliability of chip carriers surface mounted to a standard FR-4 epoxy/glass PWB to those mounted on a FR-4 epoxy/glass PWB with a copper-clad lnvar core. Our results concur with those of others; that is, the use of a CTE matched core significantly improves the resistance of the solder joints to thermal fatigue. Close metallurgical examination, however, reveals that although the solder joints associated with the Cu-clad Invar core PWB do not fail by the mechanism typical for a thermal expansion mismatch (i.e., cracks originating in the high stress region of the solder), they do exhibit intergranular cracking and void formation within the solder structure. These defects appear to be caused at least in part by the thermal degradation of the solder. This indicates that solder joint composition and structure are also important to the reliability of HCC/PWB interconnects. The differences in the solder joint behavior in the thermally matched and mismatched systems are discussed. View full abstract»

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  • Conductive and Insulative Particle Size Effects on the Electrical Properties of RuO2Thick-Film Resistors

    Page(s): 372 - 373
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    The particle sizes of Ru02and glass powder have direct effects upon the resistance value, TCR, and current noise. View full abstract»

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  • A Low-Stress Low-Temperature "Micro-Soldering" Technique for Making Electrical Contacts to Semiconductor Crystals and Thin Film Materials

    Page(s): 397 - 402
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    A new method for the creation of electrical contacts to semiconductor materials is described. The method utilizes a standard thermocompression bonder apparatus to carry out the bonding motions but does not utilize the compression action to effect the bonding. A small ball is formed at the end of a length of an appropriate contact metal wire by the bonder flame-off system, and a metal or metal alloy is picked up by the ball. Subsequently the ball and alloy metal is brought into contact with the surface of the material to be contacted without pressure. The material contacted in such a manner is not subjected to global heating, significant localized high temperatures, or thermal or mechanical shock, in contrast to the thermocompression or ultrasonic bonding methods. This technique generates contacts with good characteristics, but no degradation of device properties or electrical characteristics is induced by the contacting process. Metal-semiconductor and metal-metal contacts may be formed by the micro-soldering method. View full abstract»

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  • Evalutation of Different Types of Contact Aid Components for Aluminum-to-Aluminum Connectors and Conductors

    Page(s): 313 - 320
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    A number of contact aid compounds commonly used for aluminum-to-aluminum connectors and conductors were evaluated on the basis of their effect on the contact resistance-force/torque relationships, stability to thermal degradation, consistency, and ability to protect the contact against fretting. The results showed that the use of the contact aid compounds markedly improves the contact properties of a joint and significantly reduces its susceptibility to fretting. View full abstract»

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  • How to Calculate the True Permissible Leak Rate and How to Raise it by Four Orders of Magnitude

    Page(s): 359 - 365
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    This paper is in two parts. The first part presents bad news and the second part good news. The bad news is that the maximum permissible leak rates specified in the military standards are too large by at least three orders of magnitude, and that for microelectronic packages the true values are too small to measure. The good news is that the true permissible leak rate can be raised by four orders of magnitude or more by the inclusion in the package of a means to capture water as it enters through small leaks. Three different means are presented. View full abstract»

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  • Convective Immersion Cooling of Parallel Vertical Plates

    Page(s): 343 - 351
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    Complete immersion of electronic assemblies, in fluids of appropriately high dielectric strength and low dielectric constant, offers a most promising alternative to conventional thermal control measures. The present study is aimed at providing an analytical basis for the design and optimization of convective immersion cooling systems by focusing on the analytical development and experimental verification of composite relations for the natural convection heat transfer coefficients prevailing along the Surfaces of immersed, uniformly heated plates in both symmetric and asymmetric configurations. View full abstract»

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  • Electrical Characteristics of a Superconducting High-Speed Computer Package

    Page(s): 374 - 385
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    The interconnection of chips using Josephson circuitry for building a superconducting computer requires a special package. The electrical characteristics of this package will determine the speed and quality of chip-to-chip signals and therefore have a significant effect on overall computer Performance. The package consists of different parts which are wired together with special connectors. The wiring paths are formed with superconducting lossless transmission lines which can propagate extremely fast wavefronts. When a transmission line must be connected to another transmission line on another adjoining package part, the special connector ties the two together. These connectors have self and mutual inductances which create an electrical discontinuity. Some of these connectors are also used to tie together the ground planes of adjoining package parts. A useful parameter which affects the self and mutual inductances of these special connectors is the ratio of the number of signal connectors to the number of ground connectors, called SGCR. For most special connectors, making SGCR small reduces the size of the inductances. Examples of the affect of SGCR are shown. In addition, special techniques have to be used to calculate the inductances and some examples of this are given. Another important Parameter is G, and the size of G determines the distortions and reflection a signal incurs passing through a special connector. The ratio G = (2tauZo)/LS wheretauis the rise time of the wavefront, Z0is the characteristic impedance of the transmission line, and LS is the self inductance of the special connector. Values of Ggeq6 lead to acceptable distortion and reflections. The crosstalk between adjacent special connectors is directly due to mutual inductance and also the parameter G. Larger values of G reduce crosstalk. Allowable chip-to-chip signals in a package must constrain the cross-talk between signal paths to acceptable limits. We can calculate plots that show cross-talk between connectors as a function of signal wavefront speed (T), using the parameter SGCR. For a given receiver design which can safely accomodate some maximum cross-talk, the allowable wavefront speed versus SGCR can be determined. From this o- verall signal delay can be calculated and critical timing paths in the computer can be determined. View full abstract»

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  • Degradation of Cu-Sn/Pb Surface Layers on Aluminum Conductors by the Action of an Electric Current

    Page(s): 328 - 332
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    The effect of an electric current on the morphology of the coating layers on an aluminum conductor has been investigated. The results show that an electric current causes profound changes in the coating layers, resulting in substantial degradation of the conductor contact properties. View full abstract»

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  • The Frequency Spectrum of Electrical Sliding Contact Noise and Its Waveform Model

    Page(s): 366 - 371
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    There are many unsolved problems concerning an electrical sliding contact noise. Some relationships between the sliding contact noise and the contact force, the contact resistance and the sliding velocity have been presented by Mano. The authors have proposed a relationship between the power spectrum and the sliding velocity of the sliding contact, supposing that the fluctuation of the contact resistance is regarded as a random step function and the distribution of its amplitude is regarded as Poisson distribution and Gaussian distribution. Furthermore, the possibility of the amplitude as being a Gaussian distribution is described. The actual power spectrum of sliding contact noise as measured and analyzed by the microcomputer is studied. The frequency characteristics of the sliding contact noise is obtained and it is proposed that it can be calculated by the random step function. It also is proposed that the noise waveform is modeled by the autoregressive process. Finally the simulated waveform using the autoregressive method compared with the real waveform of electrical sliding contact noise is discussed. View full abstract»

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  • DTA and TGA Studies of Four Ag-MeO Electrical Contact Materials

    Page(s): 352 - 358
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    The results of the differential thermal analysis (DTAt and the thermal gravimetric analysis (TGA) of four different metal oxides and their respective Ag-MeO materials indicated that the thermochemical properties of the Ag-MeO materials are directly influenced by the metal oxide components. The energies required to bring the different Ag-MeO materials into different thermal states were calculated, diseussed, and compared. This investigation postulates two hypotheses. First, the arc erosion loss of a contact material depends on the erosion mode. If the predominate mode is splattering, then the Ag-CdO material may be the superior to pure silver because it requires more heat to reach an equivalent thermal state. Second, the oxide, the function of which is to weaken the contact welding, tends to remain on the surface thus increasing the contact resistance. Cadmium, due to its low boiling point, evaporates from the surface. These unique properties may account for the superiority of Ag-CdO as a contact material over other single oxides. View full abstract»

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  • EPIC, a Cost-Effective Plastic Chip Carrier for VLSI Packaging

    Page(s): 386 - 390
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    With the continuing growth in complexity of very large-scale integrated (VLSI) chips, there are increasing demands for high-performance high-pin-count micropackages capable of providing high reliability protection of the chips without being unduly costly. Studies have confirmed that plastic encapsulants, particularly silicones, can provide very high reliability protection indeed. These observations led to the concept of a new plastic chip carrier, named the "EPIC," fabricated by printed circuit board technologies, which has been developed to be suitable for automated bonding and encapsulation of chips into the package, and for subsequent automated surface-mounted assembly of the EPIC onto circuit boards. Reliability evaluations of the EPIC, in comparison with established commercial small outline (SO) plastic micropackages, have demonstrated that high reliability is attainable with EPIC chip carriers and also SO packages from a few sources. Performance measurements have revealed the outstandingly better electrical performance of the EPIC over ceramic equivalents, and versions of EPIC can achieve equivalent or better thermal resistances. Cost analyses show that the EPIC starts with an intrinsically low cost and can achieve very high terminal counts (exceeding 200) while maintaining the cost advantage. Thus high performance and reliability of VLS1 packaging is achievable cost-effectively. View full abstract»

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  • Rapid Evaluation Methods for Thick-Film Multilayer Conductor Systems for Hybrid Microcircuits

    Page(s): 321 - 327
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    Palladium-silver and copper thick-film conductors are now being widely used instead of gold in the fabrication of multilayer hybrid microcircuits, with a possible consequent increase in the risk of conductor crossover failure. Because of the potentially very large number of thickfilm material combinations available for the construction of such crossovers, evaluation methods more rapid than the 85°C/85 percent relative humidity (RH) test (currently used by British Telecom) have been investigated. A measurement of insulation resistance made after boiling in salt water and drying has been found to correlate with the results of an 85°C/85 percent RH test. A room temperature insolation resistance greater than about 3 x 1011Omegacm2 indicates a suitable materials combination for Pd/Ag crossover systems, while a somewhat lower value may be acceptable for copper. Measurements at high temperatures of insulation resistance and time-to-failure under bias did not, however, correlate with the 85°C/85 percent RH results and were only useful for predicting time-to-failure under dry conditions. View full abstract»

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Aims & Scope

This Transaction ceased production in 1993. The current publication is titled IEEE Transactions on Components, Packaging, and Manufacturing Technology.

Full Aims & Scope