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Electronic Components and Technology Conference, 1991. Proceedings., 41st

Date 11-16 May 1991

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  • 1991 Proceedings. 41st Electronic Components and Technology Conference (Cat. No.91CH2989-2)

    Publication Year: 1991
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    Freely Available from IEEE
  • The application of computerized processing techniques to manipulate and enhance the flow of non-Newtonian viscoelastic thixotropic materials in a production environment

    Publication Year: 1991 , Page(s): 597 - 604
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    The flow process discussed takes advantage of the complicated, thixotropic nature of an RTV silicone paste using digital processing techniques and computer control to accomplish the desired processing result. The objective was to generate a barrier dam on hybrid circuits in substrate form using a silicone paste. The dam would later be filled in. The paste has to be precisely extruded through a geometrically complicated nozzle to produce the dams on up to 48 separate circuits per substrate simultaneously. The combination of a complicated flow path and a non-Newtonian, thixotropic material produced an inconsistent result. Evaluation of the material indicated that it exhibited stable upper and lower Newtonian regions in viscosity vs. shear rate plots. However, in the region between these two, the viscosity showed a very strong dependence on both shear rate and time at shear. Results showed that process conditions were imposing shear rates on the material which corresponded to viscosities that were highly dependent on both shear rate and time at shear. Since the volume of material extruded was fixed by the geometry of the dam and flow rate through the nozzle restricted by mechanical limitations, the shear rate as a result of flow was essentially fixed for the process View full abstract»

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  • Thin film surface mount fuses

    Publication Year: 1991 , Page(s): 428 - 430
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    The required characteristics for SMD (surface mounted device) fuses are small size, accurate current-sensing, very fast reaction (blow) time, and the ability to provide surge resistance (time lag fuses). It has been demonstrated that all these requirements are satisfied by the thin-film fuse. The thin-film technology provides a high level of control of all fuse parameters, thus accomplishing true and economical custom design capabilities to meet a wide range of fusing requirements. The photolithographic production method allows for a great variety of fuse element designs and substrate types to be combined for creating a wide range of fuse chips. This includes any size standard SMD chips and non-standard chips with a variety of electrical characteristics. Critical parameters such as fuse speed can be programmed to optimally satisfy application requirements. The hermetic structure of the thin-film fuse gives the device excellent environmental reliability View full abstract»

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  • Mechanical integrity of the IC device package-a key factor in achieving failure free product performance

    Publication Year: 1991 , Page(s): 450 - 456
    Cited by:  Papers (4)
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    A methodology has been developed to maximize product hardware integrity and practically eliminate service affecting field failures. This methodology starts with the analysis of the field failures reported over a period of 5 to 10 years. Failed parts are analyzed and similar failures are reproduced in laboratory conditions. This procedure allows researchers to identify the failure mechanisms and the factors that initiate and accelerate device degradation. Contrary to general belief, silicon temperature was eliminated as a major failure cause. In fact, a very weak correlation was found between silicon maximum temperature and field failure probability. Temperature cycling due to power and environmental changes was found to have a stronger impact on overall device reliability. Device packaging and especially the silicon chip interconnect were found to be the most sensitive part of the entire assembly. The degradation of the device packaging occurs, in most cases, faster than the degradation of the silicon itself. Most of the parts fail mechanically long before any apparent degradation of the device electrical performance View full abstract»

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  • Complications in life prediction estimates at elevated temperatures in lead/tin solders during accelerated cycling

    Publication Year: 1991 , Page(s): 667 - 670
    Cited by:  Papers (2)
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    It was reported previously that cyclically tested Pb/Sn solders of different compositions exhibited a complicating anelastic effect. The storage and recovery of anelastic strains suppress damaging creep strain from being stored, thus causing nonconservative life prediction estimates, and result in complications with respect to accelerated testing. These complications were at that time believed to be characteristic of only eutectic solders at near ambient temperatures. It is now found that these complications exist for high-end Pb solders and at higher temperatures. Experiments done on 90/10 Pb/Sn solder indicate that the anelastic strains are not due to an interaction between the lead and tin phases. This leads to the conclusion that grain morphology would play an important role in determining anelastic responses in solder. The effect of grain size on accelerated cycling is also discussed View full abstract»

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  • Solder interconnections for SMT selective line coupling

    Publication Year: 1991 , Page(s): 629 - 635
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    Prior to the solder interconnect technology (SIT), the mode of operation for single-in-line memory module (SIMM) build was to design one printed-circuit card for each assembly build. Solder interconnection is designed to reduce the number of printed-circuit card designs. They are beneficial to applications requiring multiplex signal lines and are produced by unique solder-mask designs and personalized by use of surface-mount-technology (SMT) process. The masks are designed in conjunction with solder interconnects on card surfaces and, with assigned apertures, allow solder to be applied on selected connections. While solder interconnect allows flexibility, its design is critical in order to ensure high reliability, manufacturability, and proper electrical parameters. Hardware has been qualified, manufactured, and tested for these attributes in an SMT process View full abstract»

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  • A low temperature cofired multilayer ceramic delay line with copper conductors

    Publication Year: 1991 , Page(s): 127 - 133
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    A distributed type chip delay line made of low-temperature fireable ceramics cofired with copper conductors has been developed. This product has very good stability at high frequency, metal shield layers built inside the chip, and features high reliability. This delay line is expected to be used for various high-frequency circuits, especially those requiring small devices: optical link interfaces, high-frequency measurement equipment, and supercomputers, for example View full abstract»

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  • A multilevel epoxy substrate for flip-chip hybrid multichip module applications

    Publication Year: 1991 , Page(s): 593 - 596
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    A multilevel substrate consisting of two portions of a multiple multilayer is discussed. One portion is thicker than the other, reinforced by organic fiber in each layer; the other is an unreinforced thick film which forms low dielectric-constant layers. A sophisticated epoxy-resin two-dimensional support, but its adhesion strength between the epoxy layers, stabilizes the elongation, shrink and warp by one-order smaller compared to the substrate of FR-4 with inorganic reinforcement. The resin of an aromatic-amine adducted type may lower the dielectric constant making it suitable for high-frequency circuits and it is an excellent acceptor of both copper-foil and copper-plated electrodes. This two-portion substrate enables ideal flip-chip bonding on thick-film hybrid circuits, gives the necessary impedance of semiconductor-circuit, and leaves a compatible zone for wire bonding and a reflow soldering View full abstract»

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  • Hermetic sealing process with atmospheric pressure vibration for LSI packages

    Publication Year: 1991 , Page(s): 611 - 614
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    The authors present a novel hermetic soldering technique, the atmospheric pressure vibration process, which periodically changes the ambient pressure while the solder is fused at the sealing area of the LSI package. The kinetic energy induced by the ambient pressure change improves the wettability of the fused solder, which results in realizing a good hermeticity of the sealing area without mechanically handling the package. The sealing apparatus is made to control the two key parameters of the kinetic energy, the amplitude and the risetime of the ambient pressure change. The mechanism of this process to improve the hermeticity is investigated with a soft X-ray micrograph analysis for the sealed packages View full abstract»

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  • Copper polyimide multilayer substrate for high speed signal transmission

    Publication Year: 1991 , Page(s): 14 - 19
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    Copper-polyimide substrate has been developed for high-speed signal transmission use. This substrate is combined with thick-film cofired technology and thin-film multilayer technology, and it is effective for higher-density packaging use. By using copper-polyimide multilayer substrate with tight tolerance cofired alumina ceramics in conjunction with highly conductive internal metallization, electrical performance in the high-frequency region has been improved. The results of environmental reliability tests and high-frequency evaluations indicate that these products are ready for application View full abstract»

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  • Electroless gold plating for high density packages

    Publication Year: 1991 , Page(s): 26 - 29
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    A high-density package manufacturing process is briefly described. The role, performance, and application of the electroless nickel and gold plating in the IC package manufacturing process are discussed. The superiority of electroless plating over electrolytic plating is shown. It is concluded that electroless nickel-boron and gold plating for high-density packages provide excellent solderability, corrosion resistance, and electrical performance to meet the requirements of the VLSI fabrication process. Electroless plating is found to be the best choice in multilayer ceramic package manufacturing, especially in high pin (lead) count IC package manufacturing View full abstract»

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  • Investigation of the adhesion mechanism of NiCr layers on Al2 O3 and AlN substrates

    Publication Year: 1991 , Page(s): 134 - 140
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    Sputtered NiCr layers on Al2O3 and AlN substrates show a very high adhesive strength in pull tests. An effort was made to investigate, with analytical procedures, the adhesion mechanism responsible for this. For the characterization of the surfaces and layers, element analyses were carried out with X-ray photoelectron spectroscopy and Auger electron spectroscopy. High-resolution transmission electron microscopy (HRTEM) studies were performed on a qualitative basis in order to obtain lattice fringes and lattice images of the thin overlayer and the substrate in near-interface regions. The results obtained lead to the conclusion that, with both ceramics, the good adhesion is due to the chemical bonding between Cr, Al, and O View full abstract»

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  • Sealed chip-on-board circuit protection

    Publication Year: 1991 , Page(s): 198 - 202
    Cited by:  Papers (11)  |  Patents (1)
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    Results from sealed chip-on-board developmental studies for digital, analog, and microwave circuits are presented. This includes environmental screening of hermetic passivation coatings for chips and their interconnects, epoxies and silicone gel as encapsulation for mechanical protection of the assembly, and films for protecting the soft gels. A test plan generated by the Reliability Analysis Center was used as the basis of a factorial design of experiments to conduct military environmental tests on samples comprising large triple track resistors mounted on high-density, fine-line, polyimide aluminum circuits. This resulted in selection of one passivation for hermetic protection and one epoxy and two silicone gels for mechanical protection. Application criteria for military systems are presented View full abstract»

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  • Experimental electrical characterization of high speed interconnects

    Publication Year: 1991 , Page(s): 85 - 88
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    The authors present measurement techniques to experimentally characterize the electrical performance of interconnects on printed circuit boards and multichip modules. Novel techniques for calibrated measurements of two-port and three-port structures are presented. Measurements of a transmission line, a via, and a tee on a printed circuit board are presented View full abstract»

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  • PECVD silicon and nitride postbond films for protecting bondpads, bonds and bondwires from corrosion failure

    Publication Year: 1991 , Page(s): 738 - 744
    Cited by:  Papers (2)
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    It was demonstrated experimentally that the ultimate strain of PECVD thin-film silicon nitride coatings increased as the films were made thinner, giving them better mechanical properties for protecting underlying bulk Al structures such as bondwires, bond, and bondpads. In sections of under a micron, the films did not crack over Al bonds or bondwires during standard industrial temperature cycling. Temperature ramping tests indicated that 1000-A films had at least three times the ultimate strain expected from bulk values. Film thickness was consistent around bondwires and in the vicinity of the bonds from the plasma deposition. The most susceptible part of the films was the area in the occluded cavity under the foot of the bond. The spread of Al metallization corrosion under these films proceeded at a slower rate than the thinner films due to their more favorable mechanical properties. The results of this project indicate that PECVD silicon nitride films are good candidates as protective films for mounted and bonded microelectronic or hybrid devices and have the potential of outperforming polymeric films by a wide margin View full abstract»

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  • Development of leadframe for COL and LOC package

    Publication Year: 1991 , Page(s): 210 - 214
    Cited by:  Papers (1)
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    The COL (chip-on-lead) structure is used for the 4-Mb DRAM, because this structure makes it possible to get a large chip into a comparatively small package. For application to the COL package; a leadframe with insulation films has been developed. To prevent the problem of bubbles in the adhesive HM-1, a nonsolvent adhesive is used. The problem of film warp is solved by dividing the sticking area of the leadframe into two parts. A novel sticking method, with two sticking stages, is developed. This obtains both a high sticking speed and high accuracy of the film position. A mass production system is established using the two-stage method. It is expected that this leadframe with film will be used for a large-scale memory IC package and QFPs (quad flat packages) with many outerleads View full abstract»

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  • The design of ES/9000 module

    Publication Year: 1991 , Page(s): 50 - 54
    Cited by:  Papers (4)
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    The technology enhancements appearing in the glass ceramic TCM (thermal conduction module) of the ES/9000 systems are described and related to the system performance requirements. This module is larger, holds more circuits, supports higher power chips, and has more and faster signal connections than any of its predecessors. To assure the operational integrity of this module, much attention was paid to its electrical design. The interconnection and noise rules were carefully generated through extensive modeling and circuit simulation. Sophisticated design tools were generated to keep track of the noise and estimate the delay on each and every path in the TCM. A comprehensive set of measurements on specially built test vehicles measured in specialized testers was used to confirm the accuracy of the modules and rules. As a result, the TCM can support more functions and faster cycle times at a better quality level View full abstract»

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  • Low-temperature CMOS-a brief preview

    Publication Year: 1991 , Page(s): 544 - 550
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    The advantages of operating CMOS at liquid nitrogen temperature (LN) are attributed to increased carrier mobility, reduced subthreshold swing, increased conductivity, reduced leakage, an improved device and circuit reliability such as electromigration ionic migration, and latchup. The gain in performance compared to room temperature (RT), however, begins to erode as the channel length is decreased below one micrometer, where increased lateral field causes the drift velocity to approach its scattering limited value along a large fraction of the channel. In the limit when saturation velocity is reached along the entire channel, the improvement at LN does not exceed a factor of ≃2, after all other enhancements are considered. This gain must justify the added inconvenience and cost of operating the system at LN temperatures. As the channel length is reduced to deep submicrometer, below ≃0.15 μm, operating at low temperature could become a necessity rather than mere improvement over RT, because of the lack of a room-temperature process and device design point View full abstract»

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  • Resistance drift in aluminum to gold ultrasonic wire bonds

    Publication Year: 1991 , Page(s): 859 - 865
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    It is noted that the literature contains many instances of reliability problems associated with the aluminum wire to gold bond system. The authors, in evaluating the potentials of this technology, experienced similar problems and initiated some fundamental studies to enhance their knowledge base. The system of interest consisted of 0.002-in. diameter Al-1% wire ultrasonically bonded to Ni-Au electroplated Cu printed circuit pads. The reliability problems observed manifested themselves as resistance drifting associated with thermal aging of the sample. It was found that plating thickness, plating current density, and bath agitation strongly influenced the resistance drift phenomenon. A simple four-wire resistance test was developed to monitor for out-of-control gold plating View full abstract»

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  • Multi-layer inductor for high frequency applications

    Publication Year: 1991 , Page(s): 551 - 554
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    A novel SMD (surface mount device) coil is being developed using thin-film technology. This technology makes its possible to achieve a small and true SMD coil chip (no wound wire), with a high Q and high self-resonant frequency. The coil will soon be available in size 0805 (2×1.3×0.7 mm) and inductance up to 100 nH View full abstract»

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  • Automatic chip placement: one solution, user-benefits, and future development

    Publication Year: 1991 , Page(s): 422 - 427
    Cited by:  Patents (1)
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    The author explores generic chip placement challenges and assembly options. A specific commercial solution for automated die bonding in the microelectronics marketplace, namely the MRSI-501 automated die placement system is described. The placement accuracy is ±0.002 to 0.003 in and two degrees in theta. However, the same system places flip chips to within ±0.0015 in. The system's throughput rate is 400-450 die per hour for vision-guided placements and 900 die per hour for direct pick and place. Developments in chip placement systems, including ultraprecision placement, are discussed View full abstract»

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  • Microwave dielectric constant of a low temperature co-fired ceramic

    Publication Year: 1991 , Page(s): 20 - 25
    Cited by:  Papers (2)
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    Evaluation of low-temperature, co-fired ceramic multilayer packaging material at microwave frequencies has revealed a lower dielectric constant than the standard measurement at 1 MHz. Examination of resonance comparisons in previously published works suggests similar conclusions. Measurements using various resonators produced results in agreement with the derivations from other indirect methods. Time-domain network measurements on microstrip structures designed with the 1-MHz dielectric constant and on revised structures using the newly measured dielectric constant are in agreement with the newly measured values. A functional three-dimensional test structure is described View full abstract»

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  • High gain (21 dB) packaged semiconductor optical amplifiers

    Publication Year: 1991 , Page(s): 30 - 33
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    Record gains of 19 to 21 dB have been obtained reproducibly using a type of semiconductor optical amplifier package incorporating of 1.3-μm tilted-facet ridge amplifier. The authors describe the package, which utilizes a novel two-temperature-zone design to achieve a process for independent soldering of the input and output fibers. The process permits stable and efficient fiber coupling to both facets, and permits reworking of less-than-optimum fiber attachments. Since the thermoelectric coolers used to control the amplifier's temperature also serve as the heat source used for soldering, the package contributes to its own self-assembly. It is noted that simple, highly manufacturable high-gain packages, such as these, will be invaluable to the development of branched or long-distance optical links View full abstract»

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  • Positive working photosensitive polymers for semiconductor surface coating

    Publication Year: 1991 , Page(s): 564 - 567
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    A positive working photosensitive polymer for semiconductor surface coating has been developed. Two types of thermal stable polymers, polyimide with hydroxyl groups and polybenzoxazole (PBO) precursor, were examined. It was confirmed that PBO precursor is superior to polyimide with hydroxyl groups with respect to solvent and humidity resistance. But PBO precursor had only poor adhesion to silicon wafers, and their patterns were stripped easily from substrates in developing with alkaline solution. The effect of the addition of silane coupling agents and the modification of PBO precursor with silicone compound in order to improve their adhesion properties is discussed. As a result, it was found that they had excellent adhesion to silicon wafer during development when they are modified with some silicone polyimides. Through these results, a positive working photosensitive polymer with practical sensitivity and resolution was developed View full abstract»

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  • I/O options for MCNC multichip package

    Publication Year: 1991 , Page(s): 234 - 244
    Cited by:  Papers (1)
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    A strategy for signal and power connections to the MCNC multichip module is formulated. The module structure is described in detail. System trends and scaling theory are used to define requirements for three generations of multichip module technology extending to the year 2000. The state of the art of computer manufacturers and development activities of connector vendors is discussed. Pin, pinless, and flexible circuit technologies are described, with specific combinations of technologies being fitted to the MCNC substrate. The intent is to generate a menu of compatible technologies and applications View full abstract»

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