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Components, Packaging, and Manufacturing Technology, Part A, IEEE Transactions on

Issue 4 • Date Dec. 1998

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Displaying Results 1 - 19 of 19
  • [Front cover]

    Publication Year: 1998 , Page(s): c1
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  • Inside front cover

    Publication Year: 1998 , Page(s): c2
    Cited by:  Papers (4)
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  • Foreword

    Publication Year: 1998 , Page(s): 529
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  • The effect of contact capacitance on current-voltage characteristics of stationary metal contacts

    Publication Year: 1998 , Page(s): 530 - 540
    Cited by:  Papers (1)
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    This paper investigates experimentally the significance of the effective contact capacitance, i.e., the interfacial capacitance during the current flow, for a wide range of stationary metal contacts operating under high charge injection rates. The effective capacitance of metallic interfaces depends on the ratio between the apparent contact area (which is optically determined) and the effective contact area (which injects the electronic charges). Silver contacts having series resistance values significantly less than the contact resistance were subjected to ac high current densities (up to 500 A/mm2). The obtained i(t) and v(t) profiles were further analyzed to obtain I-V curves. Due to the phase shift between i(t) & v(t) profiles the I-V curve within a single period of the stimulating current will produce a closed loop. The area of the loop determines the interfacial electrical energy. According to the obtained results the electrical energy storage at a given metal contact, increases at: 1) higher ampacity values; 2) lower operating temperatures; 3) higher clamping forces between the joints (elastic deformation regime) each of the above parameters acting independently. The experimental results were obtained for AgSnO2 and OFHC contacts operated in a wide temperature range, varying between −130 °C and +40 °C. The observed response of the electrical contacts is mainly characterized by the implications of the asperity contact model and dominating charge transport processes across the metallic interfaces. When standard simple equivalent circuits are used to determine contact impedance, the effective capacitance of current carrying metal contacts acquires exceptionally high values. View full abstract»

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  • The effect of ion neutralization processes on interfacial energy of stationary contacts

    Publication Year: 1998 , Page(s): 541 - 548
    Cited by:  Papers (1)
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    Practical utilization of direct measurements of the electrical energy stored at the interface of mechanically contacted metals has been used as a tool to demonstrate experimentally the effect of ion neutralization processes at the interface. Due to the presence of surface asperities, interfacial cavities filled with the gas from the surrounding space may play an important role in charge transport processes, since they provide additional current paths between the non ideally contacted spots of current carrying metallic interfaces. Measurements of the electrical energy stored at the interface were performed in stationary OFHC and silver based alloy contacts in a high vacuum environment (total pressure below 10−5 mbar). The composition of the surrounding space could be determined in situ by employing quadrupole mass spectrometry. The effect of small quantities of nitrogen, oxygen or SF6 on the overall interfacial electrical energy has been investigated for the case of a contact operated at a constant current mode. The obtained experimental results demonstrate convincingly variations of the interfacial electrical energy depending on the composition of the surrounding space and the important role of the non ohmic transport processes across metallic interfaces operating under high charge injection rates. View full abstract»

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  • Arc restrikes yielding back-commutations in the contact gap of low voltage interrupters

    Publication Year: 1998 , Page(s): 549 - 555
    Cited by:  Papers (32)
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    Arc commutation from the arc chute back into the contact gap of a low voltage circuit-breaker caused by a high arc voltage pulse due to arc splitting was investigated in a model interrupter with the aid of a synthetic test method. In the experiment a well defined time after the arc left the contacts a high voltage ramp was applied across the contact gap. The criterion considered was the breakdown value of the voltage. Recovery time (in the range of 500 μs to 2 ms), geometry and materials of contacts (Cu, Ag/C, Ag/Ni, Ag/MeO) and walls (nongassing and gassing) were varied. Increasing recovery time increased the breakdown voltage significantly due to the decrease of the temperature in the contact area. The minimum breakdown value corresponded to the instantaneous reignition voltage. An increase of the wall distance caused an insignificant increase of the breakdown voltage due to the decrease of field distortion. Gassing wall materials caused slightly higher breakdown voltages than nongassing walls. Increasing contact gap from 2 mm to 4 mm increased the breakdown voltage. No influence was observed at lower (1.5 mm) and at higher contact gaps up to 7 mm. The influence of the contact material was generally little; Cu contacts yielded insubstantially lower breakdown voltages than the other contact materials investigated. View full abstract»

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  • Modeling contact erosion in three phase vacuum contactors

    Publication Year: 1998 , Page(s): 556 - 564
    Cited by:  Papers (27)  |  Patents (6)
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    A computer model was developed to simulate the unequal contact erosion measured in a vacuum contactor during three-phase AC-4 life testing. The model showed that the contact erosion rate was directly affected by the randomness of the opening time of the contacts. A probability distribution was created to simulate any degree of randomness in the opening. The model showed that repeated opening of the contactor at or near the same electrical phase angle over thousands of operations resulted in unequal contact erosion for each pole due to differences in arc energy. If there is a consistent imbalance in the arc energy one pole will erode at a significantly higher rate than the other two poles. The degree of unequal wear was dependent on the degree of randomness of contact part. The resulting unequal contact erosion would just amplify the unbalance with each subsequent operation leading to a run-away condition. A completely random opening resulted in even contact wear while synchronous opening resulted in unequal erosion. Synchronous opening of a contactor can occur from the inherent nature of the electromagnet used to operate the contactor. This model could also be used to simulate air contactor erosion. View full abstract»

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  • A generic methodology for deriving compact dynamic thermal models, applied to the PSGA package

    Publication Year: 1998 , Page(s): 565 - 576
    Cited by:  Papers (4)  |  Patents (10)
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    A novel methodology for synthesizing compact, boundary condition independent, dynamic thermal models is represented. The resulting compact resistor/capacitor network accurately predicts the dynamic junction temperature response under any arbitrary set of external cooling conditions. The network is derived in two successive steps. First, a boundary condition independent resistor network is synthesized using steady-state finite element data for a large set of practical boundary conditions. Next, the general resistor network is expanded with discrete thermal capacitors featuring the thermal mass of the package. The value of the capacitors and their exact location within the resistor network is determined using frequency response finite element data for a limited set of boundary conditions. This paper focuses primarily on the second step, i.e., synthesis of the dynamic (capacitive) network elements. The synthesis method is successfully demonstrated for two types of polymer stud grid array (PSGA) packages, the standard PSGA and the thermally enhanced PSGA. It is shown that the thermal mass of a PSGA package can be lumped into five discrete thermal capacitances. For both the standard and the thermally enhanced PSGA, the generic compact dynamic network models can predict time dependent junction temperature profiles within an accuracy of 5%. View full abstract»

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  • Coffin-Manson based fatigue analysis of underfilled DCAs

    Publication Year: 1998 , Page(s): 577 - 584
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    The continuing drive toward high-density, low-profile Integrated Circuit packaging has accelerated the spread of flip-chip technology to laminated substrates, creating direct chip attach (DCA) configurations. However, the substantial difference in the coefficients of thermal expansion (CTE) between the chip and the laminated substrates makes DCA configurations vulnerable to thermally-induced strains and the resulting solder joint fatigue. The reliability of flip-chip technology is dramatically improved by “underfilling” the gap between the chip and substrate with epoxy. The present effort is aimed at exploring the benefits of underfilling in DCA configurations. The thermo-structural behavior of an underfilled DCA is evaluated using FEM and employing an axisymmetric model of a typical DCA structure. Numerical simulations are performed for different sets of underfill material properties. The results are used to determine the parametric sensitivity of the thermal strain in the solder joints and the axial and shear stresses in the underfill material and to define the desirable range of underfill material properties. These results together with the Coffin-Manson relation are used to predict the theoretical improvement in cycles to failure. The results suggest that to minimize fatigue failure, the CTE of an underfill material should match that of solder material and its Young's Modulus should be as high as the adhesion strength of the underfill allows. View full abstract»

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  • Failure analysis of bond pad metal peeling using FIB and AFM

    Publication Year: 1998 , Page(s): 585 - 591
    Cited by:  Papers (22)
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    Aluminum bond pads on semiconductor chips play an important role in chips functionality and reliability. Bond pad peeling during wire bonding process results in yield reduction. The failure mechanisms of the peeling must be identified so that potential reliability problem of poor bond pad adhesion can be avoided. In this work, FIB, SEM, EDX, and AFM are used to identify the root causes of the peeling. The possible root causes are found to be the presence of an extra layer of thickness of 0.14 μm and the poly-silicon surface roughness asperity due to prolonged BOE etching time. View full abstract»

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  • New receptacle optical modules using ferrule-integrated chip carrier with solder-bump-bonded photonic device: Singlemode-fiber-based high-speed PIN PD receivers

    Publication Year: 1998 , Page(s): 592 - 598
    Cited by:  Papers (2)
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    A new receptacle optical module is proposed that requires no optical-axis adjustment. In this scheme, coupling a photonic device to a fiber is done basically by simple butt-joining, which is accomplished automatically by solder-bump bonding the device onto a platform with an optical fiber glued to a ceramic ferrule. To achieve this coupling, alumina chip carriers were fabricated to include a zirconia ferrule (containing a singlemode fiber). The misalignment between the fiber and the solderable patterns on the chip carrier was below 5 μm (with a cumulative distribution of 50%). Prototype MU (IEC standard, IEEE P1355) receptacle receiver modules were demonstrated. By solder-bump-bonding the photodiode (PD) onto the chip carrier, optical coupling was achieved simultaneously with electrical connection to the chip carrier. No optical-axis adjustment was required throughout the entire fabrication of the module. The module achieved wide bandwidths up to 1 and 5 GHz, respectively, with the PD's with 180- and 50-μm-diameter active areas installed inside. View full abstract»

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  • Anodic to cathodic arc transition according to break arc lengthening

    Publication Year: 1998 , Page(s): 599 - 603
    Cited by:  Papers (1)
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    Material transfer in switches and relays has been described in several reviews. Different transfer directions have been attributed to the two well known arcs type: anodic and cathodic, but no further investigations have been performed. In this paper, we use a breaking apparatus (14 V DC, 20–80 A, 0–50 mH) equipped with an arc length control device in the range of 1 μm to few mm. This device allows us to examine mass transfer with arc lengthening for pure metals (Ag, Cu), silver alloys (AgCu, AgNi) and silver metal oxides (AgCdO, AgSnO2). The main result is that arcs occur first in an anodic stage and then in a cathodic stage, and that this transition takes place at a critical length which is not affected by current and contact materials. This length has been measured to be 15–30 μm, and corresponds, for physical reasons, to a few times the electron mean free path length. In addition, the cathodic arc is divided in two stages with arc lengthening: The compensation stage where anodic loss and cathodic gain are still measured because of the mass accumulated in the earlier anodic stage; The pure cathodic stage where cathodic loss and anodic gain are measured. This last transition takes place at the net zero erosion point and depends on arc energy and contact materials. Finally, we observed different erosion rates according to these successive stages and different contact materials. For example, we measured less erosion for AgSnO2 than for AgCdO before the net zero erosion point and reversed material performance in pure cathodic stage. This shows us that material evaluation must take into account arc length/duration, to operate in a well defined erosion stage. View full abstract»

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  • An investigation of the contact behavior of electric distributed filament contacts

    Publication Year: 1998 , Page(s): 604 - 609
    Cited by:  Papers (6)
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    The findings of a preliminary experimental investigation into the contact behavior of nonmetallic, distributed filament contacts (DFC's) are reported. The study was designed to probe the effects of numerous fibrous micro-contacts upon the electro-mechanical behaviors of composite contacts and to compare the resultant behaviors with conventional metal contacts. Four composite materials, representing the variables of interest to this study, were processed into electrical contacts by two novel manufacturing methods. Static and dynamic tests reveal that DFC contact resistances can saturate at a level of as low as 10 g, and that DFC contact stability is, similar to that of metals, dependent upon the contact loads and the contact surface hardness, but nearly independent of the properties of the carbon fibers. The results suggest that it is possible to tailor DFC electro-mechanical characteristics over a range that is not possible with monolithic contact materials by the judicious selection of matrix resin, fiber loading, and surface microstructures. View full abstract»

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  • Open Forum: Editorial: Virtual product development

    Publication Year: 1998 , Page(s): 610
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  • Open Forum: The role of physical implementation in virtual prototyping of electronic systems

    Publication Year: 1998 , Page(s): 611 - 616
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  • Call for papers

    Publication Year: 1998 , Page(s): 617 - 618
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  • 1998 Index IEEE Transactions on Components, Packaging, and Manufacturing Technology — Part a Vol. 21

    Publication Year: 1998 , Page(s): 1 - 10
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  • [Back inside cover]

    Publication Year: 1998 , Page(s): c3
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  • [Back cover]

    Publication Year: 1998 , Page(s): c4
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Aims & Scope

This Transaction ceased production in 1998. The current publication is titled IEEE Transactions on Components, Packaging, and Manufacturing Technology.

Full Aims & Scope