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Parts, Materials and Packaging, IEEE Transactions on

Issue 4 • Date December 1970

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Displaying Results 1 - 6 of 6
  • Who's Who in G-PMP

    Page(s): 120
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    Freely Available from IEEE
  • Voltage Hash in Low-Current DC Vacuum Arcs

    Page(s): 138 - 143
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    The nature and mechanism of the high-voltage pulses in the anode region of copper-vapor arcs have been investigated. Arcs are drawn between a 1.3-cm-diameter anode and a 5-cm-diameter cathode in the dc range of 30-400 A. Prior to anode spot formation and at constant current, the arc voltage exhibits HF pulses superposed on the dc voltage. The amplitude and frequency of repetition (= 500 kHz) of these pulses is highly erratic, and the total instability is evidenced as voltage hash. The hash amplitude increase with both arc current and contact spacing and, at 2.5 cm, varies from several tens of volts at 30 A to several hundreds of volts at 400 A. The hash is attributed to fluctuations in vapor and plasma density in the anode region. Although these fluctuations appear unrelated to the gross motion of the cathode spots, streak photographs indicate a time-variant cathode evaporation that may contribute to the hash phenomenon. A second contributory mechanism is suggested from experience of hash in the anode region of fluorescent lamps, and involves quasi-periodic emission from the anode. View full abstract»

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  • Electrical Characteristics of Contacts Contaminated with Silver Sulfide Film

    Page(s): 129 - 137
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    Frequently the electrical performance of silver contacts is impaired by the unavoidable growth of a sulfide film on the mating contact surfaces. In the case where one or both of the electrodes are silver, or partly silver, and a silver sulfide film is formed on one or both of the electrodes, the electrical performance is greatly deteriorated and is among the most complex found on contaminated contacts. A recent study of the electrical performance of various sulfided contacts is reported that showed that they are characterized by an increased contact resistance that is dependent on the voltage polarity, by a nonohmic relationship between the contact voltage and current, and by a resistance that changes with time. A theory is proposed to account for the observations made with these contacts that is based on the semiconduction properties of silver sulfide, the high mobility of positive silver ions in silver sulfide, the tunnel effect, the widening of established conduction channels through the film by electrical forces (B fritting), and the crystal structure of silver sulfide, which can be found in either one of two forms depending on its temperature. View full abstract»

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  • Relation of the Particle Size of RuO2in Cermet Resistor Inks to the Electrical Properties of Fired Resistors

    Page(s): 144 - 146
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    It has been reported that the electrical properties of RuO2-.based thick-film resistors are dependent on the particle size of the Ru02in the inks used to make the resistors. In order to explain this dependence, a mathematical analysis was made to see if the "mixing rule" equations used to blend end-member cermet resistor inks to give inks with intermediate resistance values could be applied. This analysis led to the conclusion that these mixing rules cannot be used to explain file changes in resistence and the temperature coefficient of resistance (TCR) that occur as the particle size of the RuO2in the inks is varied. It was found, however, that alterations in the elemental resistor structure associated with the variations in the particle size of the oxide could be used to explain the changes observed. View full abstract»

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  • Calculation of Thermally Induced Mechanical Stresses in Encapsulated Assemblies

    Page(s): 121 - 128
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    A procedure is given for the calculation of thermally induced mechanical stresses in electronic assemblies. This procedure can be used to calculate both elastic and plastic deformation during thermal cycling of multielement assemblies with complex configurations and heterogeneous material properties. It will give the strain (or stress) in each element at any temperature in the thermal cycle as the element undergoes elastic deformation, captive plastic deformation, or thermal ratchet. Several encapsulated systems were analyzed to demonstrate the applicability of the calculations to real assemblies. In one example, it was demonstrated that encapsulated electronic systems are subject to thermal ratchet. For the environmental temperatures used, it was shown that the assembly would grow (or ratchet) on each thermal cycle until one of the elements broke. It was found that thermal ratchet could be avoided by either decreasing or increasing the thickness of the encapsulant. In another example, a foamed cordwood module was analyzed to determine the effect of lead length on the stresses developed in a glass-cased component. It was shown that a small increase in the length of the component's leads significantly increased the stresses in the component. View full abstract»

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Aims & Scope

This Transaction ceased production in 1971. The current publication is titled IEEE Transactions on Components, Packaging, and Manufacturing Technology.

Full Aims & Scope