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Components, Hybrids, and Manufacturing Technology, IEEE Transactions on

Issue 2 • Date June 1979

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Displaying Results 1 - 18 of 18
  • Who's Who in CHMT

    Page(s): 157
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    Freely Available from IEEE
  • Foreword

    Page(s): 158
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    Freely Available from IEEE
  • Thermal Oxide Film Deposition Monitoring Algorithm

    Page(s): 263 - 265
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    A software-implemented algorithm for controlling the amount of thermal oxide film grown on a substrate, along with some experimental results, is presented. View full abstract»

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  • Temperature Aging of External Connections Condensation Soldered to Ti-Pd-Au Thin Films

    Page(s): 180 - 195
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    Soldering has a number of advantages for making external connections to HIC's (hybrid integrated circuits). However, recent investigations report a potential reliability problem due to the formation of brittle intermetallic compounds. An investigation of the mechanism of solder joint strength degradation due to the temperature aging of clip-on terminals to HIC Ti-Pd-Au thin films is described. The investigation consisted of aging circuits at elevated tempeatures, measuring bond strength, and assigning the failure mode. Important variables evaluated included gold thickness, conductor thermal stabilization .prior to soldering, and solder reflow time. Activation energies in the range of 1.1 to 1.7 eV were calculated from the observed solder bond strength decrease. From an Arrhenius-type extrapolation the acceptable mean solder bond strength for all films tested exceeds a 40year 50°C requirement. These included thermally stabilized films with both 2- and 5-µm thick gold, and unstabilized film with 5-µm thick gold. Metallographic cross sectioning and chemical analysis of solder bonds were used to identify the intermetallic compounds and the resultant weak bond interfaces. Activation energies for the solid state diffusion and intermetallic formation of solder with gold, palladium, and copper are in the range of 0.6 to 1.0 eV. These are significantly less than the effective activation energies measured for the degradation of the solder bond strength. Several rate-limiting processes are proposed to explain this. A model consistent with the analytical results and bond strength measurements is included. View full abstract»

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  • Solid-State Two-to Four-Wire Hybrid Function

    Page(s): 269 - 272
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    A new type of solid-state two- to four-wire hybrid function using photocouplers is proposed which employs the combinations of the traditional differential, push-pull, and cascade techniques. It has a good linearity and temperature dependence over a wide operating frequency from dc to 100 KHz. View full abstract»

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  • A High-Stability RC Circuit Using High Nitrogen Doped Tantalum

    Page(s): 221 - 225
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    A fabrication process and reliability studies for RC hybrid integrated circuits utilizing alpha tantalum capacitors and tantalum nitride resistors are described. The alpha tantalum used in this study was reactively sputtered tantalum film containing from 10-20 atomic percent nitrogen and has a body centered cubic structure. The ac and dc characteristics of the alpha tantalum capacitors are in agreement with those shown by Anders and Rottersman [5], [6]. The longterm thermal stability of these capacitors is shown to be at least three times better than for beta tantalum capacitors. Accelerated life tests at various voltages show the alpha tantalum RC circuits to be at least equivalent in reliability to those using standard beta tantalum capacitors. The RC product shows excellent temperature compensation and stability during accelerated parametric aging tests which were done on production RC filter circuits. View full abstract»

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  • Accelerated Reliability Evaluation of Trimetal Integrated Circuit Chips in Plastic Packages

    Page(s): 172 - 179
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    Accelerated step-stress and constant-stress reliability tests have been performed on trimetal MOS and bipolar integrated circuit chips beam-tape bonded in both plastic and hermetic packages. Wire bonded units of like construction were also included for control purposes. The work is being performed in three phases. Phase I, already completed, was a study of the feasibility of hermetic gold metallized chips, beam-tape bonding, and plastic packaging being married into one low-cost high-reliability package. Phase II of the program, currently in progress, is being conducted to develop activation energy(s) for the chip-package system. During the first two phases two reliability problems were discovered and resolved. Phase III of the program, yet to be accomplished, will be a complete reliability assessment of the high-reliability low-cost system. View full abstract»

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  • Temperature Coefficients of Resistance: A New Approach

    Page(s): 265 - 269
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    An empirical relationship is developed for the temperature variation of thick-film resistors. From this two coefficients are derived which can be used to predict resistance and tracking variations at any temperature. The predicted results are compared to actual mea- surements. View full abstract»

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  • A Method for the Rheological Characterization of Thick-Film Pastes

    Page(s): 232 - 239
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    A complete rheological profile of a thick-film ink can provide an understanding of the effects of composition on properties and enables one to predict and control the screening behavior. A complete profile includes the thixotropic and pseudoplastic properties as well as the viscosity behavior during post-shear recovery when leveling takes place. This paper presents a set of experimental techniques with which to measure shear thinning and recovery as experienced during the screening process. The basic problem in the measurement of the viscosity profile of a pseudoplastic paste during recovery is that the shearing involved in making the measurement itself causes a change in the paste viscosity. We have developed a technique which measures viscosity at essentially zero shear. The method involves the relaxation of a spring-driven cone against the viscous drag of the paste repeated at short intervals during the recovery. The moment of inertia of the cone, the compliance of the viscometer spring, the cone geometry, and the shearing action are critical factors to consider in obtaining accurate and reproducible values of the viscosity. Experimental data describing the measurement of viscosity of Newtonian standards and of the theological characteristics of thick-film pastes are presented and discussed. View full abstract»

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  • Performance of New Copper-Based Metallization Systems in an 85°C, 78% RH, SO2Contaminated Environment

    Page(s): 159 - 171
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    The performance of Ti-Pd-Cu-Ni-Au (TPCNA), Ti-CuNi-Au (TCNA), and Ti-Cu metallization systems in an 85°C, 78% RH environment contaminated with SO2was compared with that of the standard Ti-Pd-Au (TPA) metallization. Electrolytic and galvanic corrosion failure modes were identified for encapsulated (RTV silicone tubber) and unencapsulated triple track conductor specimens fabricated using each of the above thin-film technologies. Electrolytic corrosion was studied by biasing TPCNA, TCNA, Ti-Cu, and TPA triple track specimens in the corrosive environment and measuring in situ leakage currents as a function of time. Median leakage currents for the unencapsulated Ti-Cu specimens were significantly lower than median currents for any of the other unencapsulated groups. Failure of the TPA was due to Pd migration and the formation of dendrites between oppositely biased conductors. Both TPCNA and TCNA showed extensive Cu dendritic growth. Significantly fewer Cu dendrites were observed on the Ti-Cu specimens. TPCNA and TCNA failures were also due to chemical and galvanic corrosion which filled the space between the tracks with hygroscopic salts. The salts were identified by X-ray diffraction to be NiSO3º6H20 and NiSO4º6H20 after 237 hours. After 1302 hours the initial salts had become amorphous and a basic nickel sulfate was found. Ti-Cu had only a light tarnish, ~1000Å thick, after 1302 hours. This consisted of Cu20 and an unidentified minor phase containing S. Galvanic attack at the Cu-Ni-Au interfaces occurred on TPCNA, TCNA, and the Cu-Ni-Au external leads. Oxidation of Ni in the galvanic cell caused delamination of Au on the triple tracks and separation of the bulk of the lead from the Au layer in the bond areas. Galvanic attack was also observed at the Ti-Cu interface for TCNA with sputtered or normally evaporated Ti-Cu layers. TCNA with a graded evaporated Ti-Cu interface showed very little galvanic attack and delamination. No delamination was observed for the Ti-Cu samples or at Ti-Pd-Cu interfaces of TPCNA. The RTV encapsulant prevented high leakage and dendritic growth on all coated specimens and retarded galvanic and chemical corrosion. View full abstract»

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  • Silver Migration and the Reliability of Pd/Ag Conductors in Thick-Film Dielectric Crossover Structures

    Page(s): 196 - 207
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    The relative performance characteristics of thick-film Pd/Ag conductors (0-34% Pd) for dielectric crossover structures in hybrid microelectronic circuits are described. The materials were supplied from Du Pont and Engelhard. The experiments involved waterdrop (WD) tests and temperature-humidity-bias (THB) tests at 90°C, 90% RH, and a dc bias of 5-50 V applied between the conductor electrodes for periods up to 1000 h. WD tests showed that the rate of Ag migration decreased by approximately 100 times as the Pd content in the conductor was increased from 10%-19%. However, the results of these tests were considerably scattered for electrodes of high Pd content. In addition, no conclusive results could be reached on the effect of the substrate or various encapsulants on the rate of migration. The rate of migration under THB conditions was considerably lower (10-4times) than that under the water-drop tests. Surface migration was found to be the dominant mode of failure in dielectric crossover structures. The rate of migration increased with the increasing voltage gradient. When the voltage was increased it caused an abrupt change in the capacitance and isolation resistance. The migration was more pronounced on the surface of bare alumina substrates than on substrates covered with a dielectric layer. Finally, a Du Pont 9137 glass encapsulant was found to be effective in preventing silver migration under THB conditions while an ESL 240 SB encapsulant enhanced the rate of migration. View full abstract»

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  • Heat Exchange Optimization Technique for High-Power Hybrid IC's

    Page(s): 226 - 231
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    An algorithm for the optimization of the heat exchange conditions in high-power thick-film hybrid IC's is presented. The algorithm for the placement of elements which are temperature sensitive and/or heat sources is discussed. The Powell's multivariable unconstrained optimization technique and the penalty function shifting method in constrained static optimization are proposed as tools. View full abstract»

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  • Properties of Die Bond Alloys Relating to Thermal Fatigue

    Page(s): 257 - 263
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    The differing performances of hard soldered and soft soldered power devices under cycling stresses are well understood. Hard soldered dice are often under considerable stress and may even fracture in extreme cases, but the solder itself does not degrade by fatigue after many temperature cycles. This behavior is due to the very high mechanical strengths of the hard solders between -55 and 150°C. On the other hand, soft solders transmit very little stress to the die but exhibit considerable degradation from thermal fatigue during temperature or power cycling. Both behaviors are related to the very low mechanical strengths and high ductilities of the soft solders. In this study the mechanical properties of the eutectic hard solders, Au-Sn, Au-Ge, and Au-Si, and two common soft solders, Pb-5%Sn and Sn-3.5%Ag-l.5%Sb, have been measured between -55 and 200°C. Several physical properties were also measured. An ahoy was then developed with mechanical properties intermediate to those of hard and soft solders and with a power cycling performance that approaches that of the Au eutectics. A model is presented which relates the fatigue behavior of hard, soft, and intermediate solders to their mechanical properties. View full abstract»

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  • A Low-Cost Thin-Film Microcircuit Process

    Page(s): 218 - 221
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    A low-cost thin-film microcircuit conductor/resistor technology is developed which offers reduced material costs, a simple fabrication process, relatively low resistor temperature coefficients, and low resistance conductor metalization. The process uses copper for the conductors and Kanthal for the resistors; the process is compatible with certain selective etches to realize a subtractive process. View full abstract»

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  • Active Device Prescreening for Hybrids

    Page(s): 247 - 254
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    An investigation was conducted to find ways to reduce the number of active device failures so common in hybrid manufacturing. It was determined that a very substantial reduction in these failures can be achieved with the proper procurement, inspection, and testing of the active device chips prior to the assembly into the hybrid. A high reliability production line which uses this approach has resulted in dierelated in-process repairs which amount to only 29 percent of all the repairs, whereas the corresponding figure for another line without the above controls is 60 percent. This is mainly achieved through a) the control of the purchased active device chips through stringent procurement specifications (including wafer probing); b) incoming inspection which includes sample testing for electrical and mechanical parameters; c) visual examination of all the active device chips prior to usage; and d) mounting on headers and testing electrically all devices which have been found, through previous history, to have a high fallout rate; this comprises about 1/3 of all the transistor chips used; the devices are subsequently removed from the headers and installed in hybrids. View full abstract»

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  • Hybrid IC Structures Using Solder Reflow Technology

    Page(s): 208 - 217
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    A study of hybrid IC's produced by solder refiow technology was carried out to achieve optimum miniaturization and substantial cost reduction. Thin-film resistor and capacitor network (R-C) chips and silicon integrated circuit (SIC) chips are mounted on a multilayered thick-film conductor substrate and connected to the substrate by solder joining. The chips are first supported by solder bumps, and then they are self-aligned by the surface tension of the solder through the reflow process. This process results in a joint that compensates for the deviation and undulation of the substrates. Mechanical supports and electrical contacts of hybrid IC's are accomplished through a single reflow process. These hybrid IC's have proven to be completely satisfactory and reliable. View full abstract»

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  • The Admittance Behavior of Low-High-Low GaAs Schottky IMPATT Diodes

    Page(s): 254 - 257
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    The admittance behavior of high-efficiency high-power low-high-low GaAs Schottky IMPATT diodes is significantly different than those of Si Read type IMPATT structures. Using small signal analysis the admittance of such low-high-low structures is investigated, and the influences of the multiplication factor, recombination current, and dielectric relaxation are included. The calculations obtained on the basis of the analysis support, in general, experimental behavior observed in such diodes. Specifically, it is observed that the order in which the cutoff and resonant frequencies occur, for such structured devices, are substantially different from those of silicon devices View full abstract»

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  • A User's Performance Profile of a Thick-Film Resistor System

    Page(s): 240 - 246
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    The DuPont Birox11400 resistor system has been successfully used by Sylvania for several years. However, only recently has it become practical to meaningfully track the performance on a production lot basis by using a data acquisition system centered on an HP 9825 calculator. During a 39-week period in 1977-1978, 30 production lots of 11 types of custom precise resistor networks involving 1 836 503 thick-film resistors were processed. The overall process is described and detailed. The screen-printed materials utilized were DuPont 9791 gold, DuPont resistor decades (100Omega/Box$^b$through 1 MOmega/Box$^b$), DuPont 9770 platinum silver, DuPont 8185 glaze, and ESL 240 SB polymer encapsulant. The process steps were printing and firing followed by laser trimming, polymer encapsulation, lead attaching, solder dipping, and testing. The testing followed MIL-R-83401A requirements for class M resistor networks. Thus every production lot was statistically sampled and subjected to thermal shock and power conditioning tests as detailed by MIL-STD-105 and MIL-STD-202 specifications. The tests and comparisons were performed by the HP 9825 test system which is described. Routine GO/NO GO tests were performed to satisfy the test requirements, but in addition data files were stored. These data files were subsequently accessed by software to provide statistical comparisons of the resistor distributions involving histograms resulting in a baseline reference to determine the potential yields. Furthermore, by using representative resistors, meaningful comparisons were made of the resistor distributions before and after thermal shock and power conditioning resulting in a stability baseline. As a consequence correlations of these yield and stability characteristics were made with the measured production lot variables of laser trim parameters, firing profile, glaze thickness, as-fired values, and resistor print thickness. Based upon the effects of the above variables upon the DuPont resistor system, an assessment was made of both the overall stability potential inherent in the material and the actual practical realization as obtained by the Sylvania process. 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