1979 International Microelectronics Symposium

1979 INTERNATIONAL MICROELECTRONICS SYMPOSIUM

1979 INTERNATIONAL MICROELECTRONICS SYMPOSIUM 13-15 November

The following Abstracts are taken from the Proceedings of the 1979 International Microelectronics Symposium held in Los Angeles, California. These Abstracts are published with the kind permission of the International Society for Hybrid Microelectronics, U.S.A., under whose auspices the Symposium was organised. Copies of the full Proceedings may be obtained from: I.S.H.M. Headquarters PO Box 3255 MONTGOMERY Alabama 36109 U.S.A.

Prices: I.S.H.M. Members $25.00 per copy Non-members $3O.OO Bulk orders (over 10 copies) I.S.H.M. member organisations $15.00 per copy Non-member organisations $20.00 per copy

All prices quoted include handling and postage by surface carrier to all addresses.

List of Papers SESSION 1A SESSION 2A HYBRID MICROCIRCUIT TESTING/ANALYSIS THICK.FILM PROCESSING A Universal Probing Technique for Continuity and A New Approach to Thick-Film Resistors by David F. Isolation Testing of Thick-Film Multilayer Circuits Zarnow, Naval Avionics Center, Indianapolis, IN by Robert L. Schelhorn, RCA, Moorestown, NJ Microstructural Studies of Thick-Film Resistors An Experimentally Verified Heat Transfer Model Using Transmission Electron Microscopy by Terry V. for Integrated Circuit Packages by Dale C. Buhanan Nordstrom and Charles R. Hills, Sandia Labs, and E. A. Wilson, Honeywell, Phoenix, AZ Albuquerque, NM Characterization of Burst Noise in Thick-Film Optical Alignment of Screen Printers for Liquid Resistors by Andrew Norrell, Malcolm Grierson, Crystal Displays by Jeffrey Green and Richard Myers, and Dr. Charles T. M. Chen, Univ. of South Hutchinson Industrial Corp., Hutchinson, MN Florida, Tampa, FL A New Process for Printing Fine Conductor Lines Tracking of Resistance and TCR in Thick-Film and Spacings on Large Area Substrates by Hussein Resistors Distinctions, Definitions, and M. Naguib, K. L. Kavanagh, and L. H. Hobbs, Derivations by Ronald C. Headley and Rene E. Cote, Bell-Northern Research, Ottawa, Ont., Canada Du Pont, Niagara Falls, NY The Formation of Spherical Lump on Gold Thick Electro-Optic Q-Switches for Laser Resistor Trimmers Film by Yoshikazu Nakamura, National Defense by Paul F. Parks and William L. Austin, P/M Academy, Kanagawa, Japan Industries, Portland, OR 97 98 MICROELECTRONICS SYMPOSIUM SESSION 3A SESSION 1B HYBRID MICROCIRCUIT INTERCONNECTIONS THICK-FILM MATERIALS Hybrids with TAB At the Threshold of Production Thick-Film Conductors Without Glass or Oxide by William R. Rodrigues de Miranda, Honeywell, Binders for Improved Wire Bonding in Multilayer St. Petersburg, FL Circuits by Dietrich E. Riemer, Boeing, Seattle, WA Lead Frame Bonder Modifications for More Compatibility of Copper/Dielectric Thick-Film Uniform Production Bonding by Roy J. Blazek and Materials by David E. Pitkanen, J. P. Cummings, William A. Piper, Bendix, Kansas City, MO and Jack A. Sartell, Honeywell, Bloomington, MN Characterizing Fine Wire for Thermocompression Voltage Sensitivity of High Ohmic Value Thick- and Ultrasonic Bonding by Horst P. Thiede and Film Resistors by Diane P. Williams and Dr. Jerry E. Albrecht Bischoff, W. C. Heraeus, Hanau, Sergent, Univ. of South Florida, Tampa, FL W. Germany Thick-Film Capacitors with High Q Factors by Dr. An Approach to Improved Solder Joints for Thick- Sidney J. Stein, Cornelius Y. D. Huang, and Film Hybrid Manufacturing by Donald H. Louis Ugol, Electro-Science Labs, Pennsauken, NJ Daebler, GTE Automatic Electric, Huntsville, AL An Evaluation of Thick-Film Resistors on Dielectrics Influence of Codeposited Impurities on the Thermo. by Jeffrey S. Williams and Dr. Jerry E. Sergent, compression Bonding of Electroplated Gold by Univ. of South Florida, Tampa, FL J. W. Dini and H. R. Johnson, Sandia Labs, Livermore, CA SESSION 2B HYBRID MICROCIRCUIT PACKAGING Fine-Wire Bonding to a Difficult-to-Bond-to Thick- Film Network by Robert P. Noble, Sandia Labs, A New Generation of Hybrid Packages for LSI Livermore, CA Devices by Nand K. Sharma and Dennis H. Klockow, Bell Labs, N. Andover, MA; and N. T. Panousis, and Donald Jaffe, Bell Labs Allentown, PA SESSION 4A THIN-FILM MATERIALS/PROCESSES High Density, Low-Cost Microelectronic Packaging by Dale W. Williams, Texas Instruments, Dallas, TX Laser Trimming Characteristics of Tantalum Nitride Resistors on Silicon by Ami Kestenbaum, Western Increasing Hybrid Yields with Miniblocks by Electric, Princeton, NJ Michael Probstein and Harry F. Liebman, Motorola, Ft. Lauderdale, FL Electrical Overstress Failure in Thin-Film Resistors by Jack S. Smith and William R. Littau, Lockheed, Increase Terminal to Pad-Peel Strength with a Palo Alto, CA Standardized Metallization System by Charles J. Trexler and Ernest T. Nicotera, Berg Electronics, Production of Thin-Film Networks Which Utilize New Cumberland, PA Chrome-Gold Conductors by Don A. Rathburn, Bendix, Kansas City, MO An Approach to a Low-Cost, Custom, Hermetic Hybrid Package by James, R. Sims, Phillip G. Creter, A High-Speed, High-Performance, Scanning, Thin- Joseph W. Soucy, and Saul T. Shapir, GTE Film Thermal Printhead by Edward K. Kanazawa, Sylvania, Needham, MA David M. Gilbert, and Kenneth E. Trueba, Hewlett Packard, Cupertino, CA De-Lidding and Re-Sealing of Large Resistance Seam Weld Sealed Hybrid Package Assemblies by Application of Low-Temperature Photochemical Gene A. DiGennaro and Wyatt F. Luce, Silicon Nitride to Microelectronic Packaging by Westinghouse, Baltimore, MD J. W. Peters, F. L. Gebhart, and T. C. Hall, Hughes Aircraft, Culver City, CA SESSION 3B MICROWAVE HYBRIDS An Investigation of the Solderability of NiCr-Pd-Au Thin-Film Conductor by Susumu Okamoto, MIC Package Using Thick-Film and Direct-Bond Takeshi Nakajima, Yoichi Matsuki, and Yoshishige Copper for 100-Watt L-Band Power Amplifier by Oda, Nippon Electric, Kanagawa, Japan J. Charles Gioia, General Electric, Syracuse, NY MICROELECTRONICS SYMPOSIUM 99 Platinum/Palladium/Gold Thick Films Decrease by Daniel D. Zimmerman, The Johns Hopkins Univ., Microwave Solder Assembly Costs and Improve Laurel, MD Reliability by John F. Graves, Bendix Corp., D. Hybrid Microelectronics Subcommittee of the Baltimore, MD; and M. Kline, Westinghouse, Manufacturing Technology Advisory Group An Baltimore, MD Overview by Joseph L. Ansell, U.S. Army Microwave Applications of Ferfimagnetic Pastes Adelphi, MD by N. B. Chakrabarti, Chinmay K. Maiti, S. Kal, and D. Bhattacharyya, Indian Inst. of Tech., Kharagpur, India SESSION 1C RELIABILITY/FAILURE ANALYSIS Surface Acoustic Wave Resonator Fabrication and Packaging with Emphasis on Contamination Effects Temperature Cycling of HIC Thin-Film Solder by Stephen J. Dolochycki, E. J. Staples, Connections by Dr. Harry N. Keller, Bell Labs, J. S. Schoenwald, and T. C. Lim, Rockwell Int'l, Allentown, PA Thousand Oaks, CA Effect of Surge Voltages on Thick-Film Resistors Epoxy Fabrication Techniques for Microwave by Yutaka Saitoh, Yukio Katsuta, and Keiji Hybrid Circuits by Louis P. Hernandez, Miteq, Suzuki, Nippon Electric, Kanagawa, Japan Hauppauge, NY Materials and Bonding Considerations for Thin- SESSION 4B Film Gold-Beam Hybrids, by Dr. Richard A. Glass, POLYNATIONAL Dr. Robert D. Wales, and Dr. Henry W. Lavendel, Lockheed, Palo Alto, CA Superior Performance of Thick-Film Microwave Circuits in High-Power Applications and Industrial Moisture Effect on Hybrids Containing CMOS Measuring Circuits by Walter Funk and W. Schilz, Circuits by Charles G. Messenger, RADC, Griffiss Philips, Hamburg, W. Germany AFB, NY; Robert E. Sulouff, Microelectronics Engineering Corp., Auburn, AL; and Dennis Greeley, Automatic Assembly and Chip Components for Thin Martin Marietta, Orlando, FL Film Consumer Electronic Products in Japan by Sei-Ichi Denda, Sanken Electric, Saitama, Japan; and Control of Semiconductor Failures Caused by Akira Ikegami, Hitachi, Tokyo, Japan Catering of Bonding Pads by Vidyadhar S. Kale, Teledyne, Los Angeles, CA Progress on Hybrid Technology in Italy by Roberto Dell'Acqua and Franco Forlani, Magneti SESSION 2C Marelli, Pavia, Italy HYBRID MICROCIRCUIT APPLICATIONS The Effect of Nitrogen and Nitrogen-Hydrogen Atmospheres on the Stability of Thick-Film A Large Hybrid Electro-Optical Array by Samuel Resistors by Martin V. Coleman, Standard Tele- Goldfarb, Consultant to Itek, Princeton, NJ, and communication Labs, Harlow, Essex, England Donald Colvin, Itek, Lexington, NJ Effects of Dopants on the Sheet Resistivity of Tarnish Growth on Silver Film Conductors and Its Cadmium Oxide Thick-Film Resistors by Shen-Li Relation to Potential Resistor Failure in Telephone Fu and Gi-Chang Lin, National Cheng Kung Univ., Central Offices by Fred N. Fuss, Richard F. Leach, Tainan, Taiwan and Willis H. Yocom, Bell Labs, Allentown, PA Capabilities and Limits of Ceramic Chip Carder A Hybrid Oscillator Circuit for the 30 kg Non- Computer Model for Thermal and Mechanical Hermetic Environment by Michael P. Hagen, Behavior by Frederic L. Rossi, Thierry E. Vernier, Pei-Luen Li, and Ronald T. Ogan, Honeywell, and Christian M. Val, Thompson CSF, Orsay, St. Petersburg, FL France Hybrid Programmable Driver Circuit for Testing SESSION 5B High-Speed Computer-Printed Circuit Boards by MILITARY HYBRID CONSIDERATIONS Peter L. Moran, Loughborough Univ. of Tech, Loughborough, Leics, U.K.; and G. Catlow, Standardization and Custom Hybrid Microcircuits International Computers, Manchester, U.K. 100 MICROELECTRONICS SYMPOSIUM SESSION 3C The Significance of Glass Transition Temperature HYBRID MICROCIRCUIT COMPONENTS & on Electrically Conductive Epoxy Resins in Hybrid MATERIALS Microelectronics by Frank W. Kulesza and Thomas F. Saunders, Epoxy Technology, Billerica, MA A Chemical Method for the Removal of RTV Conformal Coatings by James E. Ireland and Candia Recent Advances in Laser Hole Drilling: Manu- S. Schimelfenig, Micro-Rel, Tempe, AZ facturing Efficiencies and Cost Reductions in Hybrid Microcircuit Production by James E. Byrum, Spec Solvent Removable Coatings for Contaminant Industries, San Marcos, CA Protection of Hybrid Microcircuits by Dr. Bernard L. Weigand and Dr. James J. Licari, Rockwell Int'l, Materials and Curing Characterization of Conductive Anaheim, CA; and Edward J. Morrisey, AF Epoxide Adhesives by David M. Shenfield, Standard Materials Lab, Wright-Patterson AFB, OH Telecommunication Labs, Harlow, Essex, England Zero Firing Shrinkage Ceramic Substrates by E. Frederick Borchelt and Dr. Edward J. Smoke, Rutgers Univ., Piscataway, NJ MICROELECTRONICS SYMPOSIUM 101

Abstracts A UNIVERSAL PROBING TECHNIQUE FOR CONTINUITY AND ISOLATION TESTING OF THICK-FILM MULTILAYER CIRCUITS

Robert L. Schelhorn, RCA Government Systems Division, Missile and Surface Radar, Moorestown, New Jersey 0805 7

In order to obtain high yield at minimum cost in the manufacture of high-realiability multilayer circuits, it is essential to perform 100% continuity and isolation testing of the unpopulated circuit boards prior to committing them to final circuit assembly. The traditional approach to accomplish this type of circuit testing is to employ a probe head fixture designed specifically for each circuit configuration. As with PWBs and general hybrid circuits, this approach has been successfully employed for hermetic chip carrier type circuits. Design and fabrication of the individual probe heads, however, is a costly process and requires a relatively long turnaround time. To eliminate these disadvantages, alternative probing techniques were investigated to establish a universal probe system for testing diverse circuit configurations. Based on the repetitive patterns encountered in the limited number of package types used on these hybrid circuits, a building-block probe fixture was developed that employs unit building blocks for each group of pads associated with each hermetic chip carrier. These blocks are used in conjunction with a drilled template that defines the location of the individual probe blocks. The uniqueness of this probe fixture lies in its application of reusable probe blocks and a custom circuit template that eliminates the need to fabricate a dedicated probe head for each type circuit to be tested. This universal probe fixture permits testing of many different hermetic chip carrier type circuit boards with significant reduction in cost and turnaround time.

AN EXPERIMENTALLY VERIFIED HEAT TRANSFER MODEL FOR INTEGRATED CIRCUIT PACKAGES Dale C. Buhanan and E. A. Wilson, Honeywell Information Systems, Phoenix, Arizona 85005

Presented in this paper is the experimental verification of a finite element model for determining the temperature of an integrated circuit chip in a multi-chip micropackage. The experimental procedure involved the use of an optical pyrometer as the measurement device. The results showed excellent agreement between the finite element predictions and the measured temperature. The full finite element model development is presented in an appendix to this paper. CHARACTERIZATION OF BURST NOISE IN THICK-FILM RESISTORS A. Norrell, M. Grierson and T. M. Chen, Department ofElectrical and Electrical Systems, University of South Florida, Tampa, Florida 33620

This paper presents a technique for burst noise measurement and describes the characteristics of burst noise in thick-film resistors including (1) noise frequency spectra, (2) bias dependency, (3) annealing effects and (4) low temperature behavior. The magnitude and these characteristics of burst noise are compared to the conventional 1/f noise in thick-film resistors. TRACKING OF RESISTANCE AND TCR IN THICK FILM RESISTORS DISTINCTIONS, DEFINITIONS AND DERIVATIONS

R. C. Headley and R. E. Cote, E. 1. Du Pont de Nemours & Co., lnc., Photo Products Department, Electronic Materials Division, Niagara Falls, New York

As an aid to a better understanding of resistance and TCR tracking behavior for thick film resistors definitions of slope TCR, average TCR and jar value TCR are reviewed. Relationships between these terms are discussed. Using 102 MICROELECTRONICS SYMPOSIUM

the data obtained on a ruthenium based resistor series, TCR comparisons are made, tracking performance is examined in a graphical format, and the data are shown to fit a third degree equation. TCR tracking formulas are used to quantify the influence of print geometry and sheet resistivity. The effects of laser trimming and termination type are also discussed. A graphical method of estimating the tracking performance between different resistivities is proposed based on the commonly used "hot" and "cold" average TCR measurements. In most cases, this method can save time by eliminating the need for more elaborate TCR measurements. A "worst case" example is presented to illustrate the use of a tracking factor in calculating tracking error. Finally, a method is proposed to achieve balanced minimum tracking errors by adjusting parameters during the trimming process.

ELECTRO-OPTIC Q-SWITCHES FOR LASER RESISTOR TRIMMERS Paul F. Parks and William L. Austin, P/M Industries, lnc.

The economic usefulness of Q-switched YAG lasers for trimming thick and thin film resistors on a variety of substrates appears well accepted. The acousto-optie Q-switch has almost dominated the application of Q-switches for this work. The electro.optic Q-switch is now available for the industrial market. Q-switching electro-optically can be accomplished by either of two methods. The first is similar to the acousto- optic in that the YAG radiation is deflected by switch, thus spoiling the lasing action. A second method requires polarizing the radiation in the cavity and spoiling the hsing action by the electro-optical rotation of the polarization of the Q-switch element. Electro-optic Q-switches offers specific advantages, in many application, over the acousto-optic Q-switch. Pulses of less than 100 nano-second duration are achieved. A comparison between the two switches is reported for variation of peak power versus rep rate. Visual samples of thick film resistor trimming at various Q-switch rep rates linear speed of beam travel and lamp currents is shown.

A NEW APPROACH TO THICK FILM RESISTORS

David F. Zarnow, Naval Avionics Center, Advanced Microelectronics Engineering Staff 6000 E. 21st Street, Indianapolis, IN. 46218

This paper presents a manufacturing technology, developed at the Naval Avionics Center, based on an elementary, analytical (statistical) modeling method that succesfully "lumps" dominant factors which influence thick film resistor fabrication so that only three parameters are required to comprehensively characterize a prototype or production line. Values for these parameters, easily obtained, establish widely useful exponential predictor equations. This new approach facilitates the design of thick film resistors directly from the circuit schematic. Resistors are then ready for immediate and final production on the fabrication line. The high accuracy and precision of the predictor approach precludes the industry-accepted and often costly, lengthy, and labor-intensive preproduction reliance upon numerous prototype and redesign cycles. Thus, resistor design can be accomplished based on a given fabrication process and set of thick film materials vis-a-vis the predictor equations determined by the method, rather than on an ideal model or dubious "fudge" factors. Users can readily "second source" materials. Various material systems, akeady characterized on a given fabrication line for parameter values, can be compared quantitatively for degree of direct and indistinguishable interchangeability by simply comparing predictor equations. In addition, this paper is a guide for implementing the method which demonstrates the optimum achievement of both technical and economic objectives. Necessary matvrial and process controls were developed as part of the manufacturing technology in order to maintain the validity and long term consistancy of the predictor equations. Thermal analysis fingerprinting has proven to be an attractive means to determine "functional" lot-to-lot repeatability of materials for drying and firing characteristics. Printing characteristics of the materials are determined by dynamic viscometry fingerprinting. Printing by the "sighting rectangle" method, a simple yet extremely powerful film thickness process control, is introduced as a means of providing job-to-job conformity and continuity for the "lumped" or three parameter approach to thick film resistor fabrication. Finally, this method should prove most beneficial in establishing a universal approach to thick film resistor fabrication. Significantly, the method insures the functional equivalence of thick film resistors without limiting creativity. Distinctly different fabrication lines need only be qualified to the same predictor equation in order to establish mutual commonality of artwork, irrespective and independent of the materials used and the process "path" taken in resistor fabrication. MICROELECTRONICS SYMPOSIUM 103 MICROSTRUCTURAL STUDIES OF THICK FILM RESISTORS USING TRANSMISSION ELECTRON MICROSCOPY

Terry V. Nordstrom and Charles R. Hills, Sandia Laboratories, Albuquerque, New Mexico 87185

The microstructure of thick film resistors of the Du Pont 1400 series fired on 96% AI O at 850C has been characterized using transmission electron microscopy. Samples were prepared by a combination of precision grinding and ion milling. Each sample was examined for crystallinity, phase morphology, particle size, elemental composition and phase identification. X-ray energy dispersive spectroscopy was used for elemental composition determination and electron diffraction for phase identification. Microstructure of the 1421 (102 s2/square) material is composed mainly of crystallites (<100 nm) of lead- bismuth ruthenate in a lead bismuth silicate glass. The 1461 (106 s2/square) material is composed of lead ruthenate crystals in a lead silicate glass along with quartz crystals. For both resistors most crystallites are surrounded by the glassy phase.

OPTICAL ALIGNMENT OF SCREEN PRINTERS FOR LIQUID CRYSTAL DISPLAYS

Jeffrey Green and Richard Myers, Hutchinson Industrial Corporation, 40 West Highland Park, Hutchinson, MN 55350

Electro-optics is having an impact on many conventional microelectronic technologies. As LCDs have grown from wristwatch to control panel size, the costs and risks involved in their processing have also risen. Screen Printing is being used to increase LCD output at reduced costs. But modifications are needed to adapt the process to glass substrates. Mechanical edge-alignment is possible with thick-film hybrid circuits, but LCDs must be positioned to previous thin-film deposits. A top-mounted microscope is sometimes used to locate the substrate on the printer, but parallax is possible and the part may shift before it is printed. A better procedure is to look up through the substrate after it is locked in place under the screen. A video display of the microscope image reduces eyestrain, makes the alignment operation faster, more accurate, simpler, and permits real-time observation of the printing.

A NEW PROCESS FOR PRINTING FINE CONDUCTOR LINES AND SPACINGS ON LARGE AREA SUBSTRATES

H. M. Naguib, K. L. Kavanagh and L. H. Hobbs, Bell-Northern Research, Ottawa., Ontario, Canada

This paper describes a new process that combines the high resolution capability of thin-film technology and the non-vacuum, low-cost and large area capability of thick-film technology. The new technique is called the "Mid-Film" process. The circuit pattern is defined using photolithography as in thin films. The substrate is then fired at high temperature for sintering and bonding the material to the substrate as in thick films. The average thickness of mid-films is 0.2 mil (5 um) and their line resolution is less than 2 mil (50 um) for Au and Ag conductors on large area alumina, glass and porcelain steel substrates. The physical and electrical characteristics of the mid-films are described. The advantages and Iimitations of the new process are discussed.

THE FORMATION OF SPHERICAL LUMP ON GOLD THICK FILM Yoshikazu Nakamura, Department ofMechanical Engineering., National Defense A.cademy, Yokosuka, Kanagawa 239, Japan

The mechanisms of formation and detachment of gold spheres from gold thick films have been studied. The formation process occurs during the sintering of the gold powder. Sphere formation can be reduced by utilizing finer gold powder and higher temperatures of firing. 104 MICROELECTRONICS SYMPOSIUM HYBRIDS WITH TAB AT THE THRESHOLD OF PRODUCTION

William R. Rodrigues de Miranda, Honeywell lnc., Avionics Division, St. Petersburg, FL 33733

Tape automated bonding (TAB) applications for military hybrid microcircuits have seen more than three years of development.* During this time, several material combinations, bump and tape configurations, and bonding techniques have been explored. Small-to-moderate quantities of different configurations have been built and tested. The time has arrived for some fundamental decisions to be made, and several basic issues must be dealt with as the TAB technology is at the threshold of production. The purpose of this paper is to review Honeywell's (Avionics Division (AvD), St. Petersburg, Florida), experience with TAB for military hybrids, today's status of TAB technology including both progress and problems, trade-offs between different approaches to technology details, and areas requiring further development. A review will be made of the known and unknown cost factors. And, finally, the prerequisites for placing TAB into production will be reviewed.

LEAD FRAME BONDER MODIFICATIONS FOR MORE UNIFORM PRODUCTION BONDING

R. J. Blazek and W. A. Piper, The Bendix Corporation, Kansas City Division, P.O. Box 1159, Kansas City, Missouri 64141

Lead frame thermocompression bonding is used for the attachment of external gold and nickel plated copper leads which provide electrical contact to hybrid microcircuits manufactured by The Bendix Corporation, Kansas City Division, for the Department of Energy. Significant modifications, which included substrate heating, were made to a standard lead frame bonder to determine whether bond strengths could be improved and bond delaminations reduced compared to the bond results produced by a conventional bonder. Three conclusions were derived from this study: Substrate thin film and lead frame gold plating properties were a stronger determinant of the resultant bond strength and failure modes than the bonder and were a significant contributor to bond delaminations. Heated substrates alone did not produce better bond results than unheated substrates when using the same modified bonder and previously acceptable substrates and lead frames. A redesigned bonder, with several modifications for more effective heat and pressure control, improved the bond results on marginal substrates.

CHARACTERIZING FINE WIRE FOR THERMOCOMPRESSION AND ULTRASONIC BONDING

Horst P. Thiede and Albrecht Bischoff, W. C. Heraeus, GmbH, D 6450 Hanau, West Germany

The results of an investigation concerning the properties and use of gold and aluminum alloy wire in semi- conductors is given. For gold wire, bonding is mainly carried out by thermocompression techniques; more often in connection with high speed automatic bonders the high-temperature stability is a very important factor, achieved by adding small amounts of elements in connection with a controlled manufacturing process. Another method to improve the high-temperature stability is by using gold sheathed wire which also reduces the cost. For pure aluminum, aluminum silicon, and aluminum alloy wire, bonding is accomplished by ultrasonic techniques. The fatigue strength becomes critically important. Improvements can be achieved by selecting suitable alloys as will be described and illustrated from data obtained in fatigue tests.

AN APPROACH TO IMPROVED SOLDER JOINTS FOR THICK FILM HYBRID MANUFACTURING

Donald H. Daebler, GTE Telecommunications Systems Group, Huntsville, Alabama Various solder joint configurations have been studied in an effort to identify those parameters which might enhance the reliability of soldered hybrid assemblies utilizing discrete components with flat or round wire leads. It has been found that a component having leads formed to permit the component lead to emanate from the center of a solder pad results in lower manufacturing costs and solder joints with higher mechanical strengths than a component having leads formed with large feet covering the entire length or width of the solder pad. Soldered hybrid assemblies designed for maximum surface contact between the wire leads and the solder pad produce solder joints with approximately one half of the maximum solder joint strength that is possible to achieve. MICROELECTRONICS SYMPOSIUM 105 INFLUENCE OF CODEPOSITED IMPURITIES ON THE THERMOCOMPRESSION BONDING OF ELECTROPLATED GOLD

J. W. Dini and H. R. Johnson, Materials Development Division L 8312 Sandia Laboratories, Livermore, CA 94550 The influence of codeposited impurities of Cu, Ni, Cr, and Co on the thermocompression bondability of gold was evaluated before and after heat stabilization. Simulated hybrid microcircuits, plated with deliberately contaminated gold, were bonded to Au-plated Cu lead frames and pulled to destruction in 90-degree peel tests. As the Cu and Ni contents were increased, both the individual and average peel strengths decreased and failure modes changed from heel to substrate failures. Heating the parts (simulated resistor stabilization) improved the strengths and minimized substrate failures. Cr additions resulted in failures at the gold-gold interface for unstabilized films while Co additions reduced bond strengths.

FINE-WIRE BONDING TO A DIFFICULT-TO-BOND-TO THICK-FILM NETWORK

Robert P. Noble, Model Labs Division, Sandia Laboratories, Livermore, CA 94550

A project has been designed to develop a fine-wiring bonding capability for a difficult-to-bond-to platinum-gold thick film. Two different wire bonding systems were used to accomplish the flying wire bonding" a manually operated system and a programmable automatic system. The project is designed to yield a 95% confidence level at a 99% upper confidence limit. Analytical techniques for examining surface structure and composition included photomicrography, microscopy, surface topography and scanning electron microscopy. Pull tests were employed to assess bond strength. The results were analyzed with a computer program based on a widely accepted theory of wire bond pull testing. The work accomplished to date provides a good basis for processing reliable wire bonds, for upgrading and monitoring bonding processes, and for further bonding studies.

LASER TRIMMING CHARACTERISTICS OF TANTALUM NITRIDE RESISTORS ON SILICON

Ami Kestenbaum, Western Electric Company, Engineering Research Center, Princeton, NJ 08540

The integration of thin resistive films onto silicon IC chips offers numerous economic and technological advantages. Since tantalum nitride (Ta N) material has found extensive use as a thin film resistive material in hybrid technology, it is a logical choice for a similar role in the emerging monolithic technology. Geometries employed in IC technology design make laser trimming the only viable trimming technique. This paper discusses micromachining related aspects of the laser trimming process of Ta N films on silicon. The micromachining process is characterized by two distinct features: (1) interference effects, and (2) potential substrate damage, which combine to create a limited process window. Despite these limitations good trimming can be reliably obtained. Trimming results are presented that show the effect of the heat affected zone (HAZ) on post trim drift as well as correlation between predicted and measured increases in resistance during measure and predict routines that must be employed during trimming of active devices.

ELECTRICAL OVERSTRESS FAILURE IN THIN-FILM RESISTORS Jack S. Smith and William R. Littau, Lockheed Palo Alto Research Laboratories, Palo Alto, California

A study of thin-film resistor failure mechanisms, when subjected to an electrostatic discharge pulse, has led to the development of a predictive model for burn-out. The model offers a closed form prediction of the failure of a thin-film resistor for a given single electrical pulse of known duration. The voltage and current hence the power necessary to cause failure are given as a function of the electrical characteristics of the resistor material and the thermal characteristics of the surrounding material. An interesting result of the model rests with design application. It has been shown that a thin-film resistor can be hardened to virtually any pulsed power desired. The prediction scheme has been tested experimentally in detail on a variety of resistor materials and construction features, and has been shown to be applicable to the general thin-film resistor technology. 106 MICROELECTRONICS SYMPOSIUM PRODUCTION OF THIN FILM NETWORKS WHICH UTILIZE CHROME-GOLD CONDUCTORS

Don A. Rathbun, The Bendix Corporation, Kansas City Division, P.O. Box 1159, Kansas City, Missouri 64141

Thin film networks (TFNs), designed by Sandia Laboratories, Albuquerque, are manufactured by the Bendix Corporation, Kansas City Division, for DOE programs. The majority of the TFNs fabricated at this division utilize gold films 3 to 9 tm thick evaporated over a chromium film. The chromium film is evaporated over sputtered tantalum nitride film, and the substrate material is 0.027 in. (0.686 mm) thick alumina. The TFNs must have high film adhesion characteristics, meet high bondability requirements, and allow stable electrical parameters. Various production techniques ensure these high reliability TFNs.

A HIGH SPEED, HIGH PERFORMANCE, SCANNING THIN FILM THERMAL PRINTHEAD

Edward K. Kanazawa, David M. Gilbert and Kenneth E. Trueba, Hewlett-Packard Company, Data Terminals Division, Cupertino, California

This paper compares the various non-impact printing technologies and describes design considerations and fabrication processes for a thin film printhead. Critical steps in product and process development for a 120 character per second printhead are described. Substrate materials, thermal modeling, processing, metallurgical considerations, and reliability are discussed.

APPLICATION OF LOW TEMPERATURE PHOTOCHEMICAL SILICON NITRIDE TO MICROELECTRONIC PACKAGING J. W. Peters, F. L. Gebhart and T. C. Hall, Hughes Aircraft Company, Culver City, CA 90230

A new low temperature photochemical process for the deposition of silicon nitride films has been developed. Dense, conformal coatings of silicon nitride have been applied to microelectronic devices at temperatures as low as 100 C. The most significant advantage of the photonitride process is the fact that it avoids the generation of charged species and broad band electromagnetic radiation encountered in the plasma and sputtering processes. Data is given on the physical, electrical and mechanical properties of photonitride films deposited on silicon or glass substrates which show this material to be comparable with typical plasma nitride film A production scale reactor has been constructed and employed successfully for the deposition of nitride protective films on monolithic devices and hybrid microcircuits. Results of accelerated environmental tests on monolithic and hybrid devices are presented which show that the photonitride deposition process is compatible with all chip, component and lead bonding operations currently employed in hybrid microcircuit assembly. The photonitdde coating on hybrid microcircuits presents no impediment to repairability.

AN INVESTIGATION ON THE SOLDERABILITY OF NiCr-Pd-Au THIN FILM CONDUCTOR

Susumu Okamoto, Takeshi Nakajima, Yoichi Matsuki and Yoshishige Oda, Nippon Electric Company Ltd. IC Division

The solderability of sputtered and evaporated NiCr-Pd-Au thin film conductor system has been examined from mechanistic stand point. Evaporated films with and without heat treatment have sufficient adhesive force against strength test after soldering. While sputtered films have insufficient adhesive force, if the heat treatment is not done. In order to confirm the origin of adhesion, profiles of each composite element through film were measured using the depth profil,ng technique by AES (Auger Electron Spectroscopy). The measurement of evaporated films showed that Pd distributed uniformly even in the NiCr layer and Cr was segregated at the interface of Ta. This segregation of Cr is due to the difference in vapor pressure of Ni and Cr during evaporation. There was little difference between evaporated films with and without heat treatment. As for sputtered films before heat treatment, Pd was not found in the NiCr layer, distribution of Ni and Cr was uniform and their content was nearly the same as that of source material. The heat treatment of sputtered film changed the distribution of Cr and Pd, and made it similar to those observed with evaporated films. This change was supposed to be caused by the redistribution because of thermal diffusion. MICROELECTRONICS SYMPOSIUM 107 The above results agree with the experiences that the solderability of sputtered films with heat treatment was satisfactory. The proposed mechanism that the solderability depends on the resultant distribution of Cr and Pd through the film makes sputtering applicable to a solderable thin film conductor forming.

THICK FILM CONDUCTORS WITHOUT GLASS OR OXIDE BINDERS FOR IMPROVED WIRE BONDING IN MULTILAYER CIRCUITS

Dietrich E. Riemer, Boeing Aerospace Company, Seattle, Washington

Conventional conductor inks contain bonding agents that accumulate at the surface of the fired film. These metal oxides degrade the wire bondability. Inks made solely with precious metals and no bonding agents will not adhere to a ceramic substrate. However, the critical top conductor of multihyer structures rests on printed dielectric and not on ceramic. If vitreous dielectric is used as the last print prior to the top conductor, the softened dielectric can wet the top metal during firing and on cooling form an adhesive bond. Using unfluxed ink, a noble metal surface without any impurities and with the bondability of vacuum deposited films is achieved. The quality of wire bonds made to these pure precious metal surfaces remains high for a wide range of film thicknesses as they may occur in the fabrication of multilayer substrates in contrast to the behavior of conductor inks containing reactive bonding agents.

COMPATIBILITY OF COPPER/DIELECTRIC THICK FILM MATERIALS

D. E. Pitkanen, J. P. Cummings and J. A. Sartell, Honeywell Corporate Material Sciences Center, Bloomington, Minnesota

Non-noble thick film materials are receiving increased attention by the hybrid microelectronics industry as substitutes for precious metal pastes. Copper thick films not only provide materials cost benefits but offer performance advantages such as fine line printability, high conductivity, excellent adhesion and compatibility to conventional tin-lead solders. The major concerns associated with the copper based system have been the reliability of non-noble conductors and the absence of compatible nitrogen fireable dielectrics. The purpose of this work is to examine the component interactions and to characterize the phenomena such as interdfffusion, blistering and delamination which are encountered during processing. Presented are the comparative behavior of the interactions for several commercial copper and dielectric thick film pastes and the processing conditions which affect their compatibility. Analytical examination of the copper/ dielectric interaction zones using atomic absorption, SEM, Auger spectroscopy, X-ray diffraction and electron microprobe have identified some of the reaction products and aided in def'ming the critical components involved in the interaction zones. These studies have established that the drying cycle, the firing time and temperature, oxygen content of the firing atmosphere and the composition of the thick film pastes are rehted to the extent of interaction. From these data processing guidelines for the minimization of component interactions are suggested.

VOLTAGE SENSITIVITY OF HIGH OHMIC VALUE THICK FILM RESISTORS

Diane P. H. Williams and Dr. J. E. Sergent, Electrical & Electronic Systems Dept., College of Engineering, University ofSouth Florida, Tampa, Florida 33620

In recent years a number of companies which manufacture thick film paste have introduced a series of high ohmic value resistor pastes which are designed primarily for high voltage applications, such as the high voltage section of television sets. It is well-known that thick film resistors, particuhrly of high ohmic value, are susceptible to static discharge which can cause a permanent lowering of the value of the resistor. This paper extends the work of Himmel to include an evaluation of high ohmic value systems manufactured by Cermalloy, DuPont, ESL, and EMCA, under conditions of high voltage stress. The effects of processing parameters such as thermal annealing on the high voltage susceptibility of thick film resistors will be determined. The method used to produce the voltage pulses was capacitor discharge. The results showed a relatively high degree of stability, with the DuPont 9478 and Cermalloy 2600 being the most insensitive to high voltage discharge. 108 MICROELECTRONICS SYMPOSIUM THICK FILM CAPACITORS WITH HIGH Q FACTORS

Sidney J. Stein, Cornelius Huang and Louis Ugol, Electro-Science Laboratories, lnc., Pennsauken, NJ 08110

This paper deals with several improved and/or new dielectric and overglaze materials capable of solving some of the problems encountered in capacitor fabrication. The dielectric constants ("K") of these materials are in the range of 8 to 15 and 40 to 80. The electrical characteristics of these dielectrics, their variations when fired at different temperatures, and the effect of different electrode materials are reported. The contributions of the non-porous passivation coatings to successful operation under severe moisture, temperature and power stresses have been reported. Intermediate dielectric blends have been made and perform in a predictable fashion. Much higher dielectric constant compositions than those studied here also performed well when protected with the same dense double layer overglaze system. Generally bodies in the K15 to K80 range may require a single overglaze for reliable performance. Results show that it is practical to obtain individual capacitors as well as capacitor networks having Q factors in the 1000 to 10,000 range. Some of the low loss characteristics suggest good high frequency uses into the microwave region. Possible applications may include a variety of low capacitance value applications, including networks, filters, and delay lines. By the use of snap-strates, such capacitors may be utilized for chip fabrication by thick film multilayer techniques. Sheet capacitance values of up to 1500 pF per square centimeter may be designed.

AN EVALUATION OF THICK FILM RESISTORS ON DIELECTRICS Jeffrey S. Williams and Dr. J. E. Sergent, Electrical Engineering, College ofEngineering, University ofSouth Florida, Tampa, Florida 33620

As multi-layer thick film structures become more complex, the necessity for conserving space becomes more and more important. When resistors are to be used in multi-layer circuits, the problem is compounded since resistors must typically be fabricated as the last step of the process, since they are susceptible to refiring. With conventional resistor systems this requires that space be left open in the dielectric so that the resistor may be printed on the substrate. Not only is this wasteful of space, but printing resistors in the vicinity of a thick dielectric layer as found in multilayer circuits results in a deviation from the predicted mean value as well as an increase in the spread of the values. The obvious answer is to print the resistors on top of the dielectric. Appropriately, certain paste manufacturers have introduced systems which they claim are compatible with this process. This paper consists of comparison of the properties of these resistor systems compared with those on alumina to include the mean value, the standard deviation, the TCR, and the noise. The stability properties, both loaded and unloaded, will be evaluated as well as the effects of laser trimming. The degree of interaction between the resistor and the dielectric will be determined by the use of the SEM and EDAX. Resistor systems studied are the EMCA 5500 and the DuPont 1700 Systems.

A NEW GENERATION OF HYBRID PACKAGES FOR LSI DEVICES

N. K. Sha.rma and D. H. Klockow, Bell Telephone Laboratories, Incorporated, 1600 Osgood Street, North Andover, Massachusetts 01845 and N. T. Panousis and D. Jaffe, Bell Telephone Laboratories, Incorporated, 555 Union Boulevard, Allentown, Pennsylvania 18103

A new generation of hybrid packages for LSI devices is described. The existing hybrid technology in the Bell System was developed for beam-leaded bipolar silicon devices. In order to address future applications, it needed an extension to be compatible with non-beam leaded, MOS and bipolar LSI devices. An example is given of a hybrid which provides a functional module of high complexity combining analog and digital functions for telecommunications applications. A unique hybrid packaging approach is utilized to combine the best features of thick and thin-film technologies and various device packaging and attachment technologies. The device technologies used are MOS (for LSI) and bipolar (for MSI). The attachment technologies include die and wire bonding, reflow soldering, TAB, and thermocompression bonding. The MOS device is hermetically sealed in a ceramic chip carrier. The other devices and the remainder of the hybrid are non-hermetically protected with an RTV silicone rubber. Models have been built and have shown satisfactory performance in simulated system testing. MICROELECTRONICS SYMPOSIUM 109 HIGH-DENSITY, LOW-COST MICROELECTRONIC PACKAGING

Dale Williams, Texas Instruments Incorporated Equipment Group, Dallas, TX

Semiconductor technology has increased the density of integrated circuit chips by many orders of magnitude, but tittle progress has been made in improving density. Current advances in device performance and complexity necessitate a major emphasis be placed on high-reliability interconnection and packaging technology. Texas Instruments, under contract with the Air Force Avionics Laboratory, is evaluating the next level of interconnection above the hermetic chip carrier. To demonstrate advanced microelectronic interconnection and packaging structures, this paper will report on Texas Instruments' investigation of substrate interconnection materials, fabrication processes, repair processes, thermal management techniques, mechanical interfacing, and accelerated life test results. In addition, several comparisons will be made among chip and wire hybrids, chip carriers]mother carriers, and DIPs/PWBs that will include packaging density, cost reliability, performance, assembly automation and limits of applicability. This is an ongoing program and results are expected to be reported over the next two years.

INCREASING HYBRID YIELDS WITH MINIBLOCKS

Michael Probstein, Henry F. Liebman, Motorola, lnc.

Many papers have been written about the theoretical aspects of miniblock transistors how they are built, how they should be used, and the benefits they should provide. This paper approaches the subject from a more practical vantage point by addressing the real yield and cost advantages of miniblocks. Most papers of this type just look at the yield and cost factors associated with a hybrid which uses miniblocks. This paper does an actual comparison of hybrids which were originally designed using chip and wire, microtee, and LID technology, and have now been redesigned to use miniblocks. Direct cost and yield comparisons are made on a 1:1 basis for chip and wire vs miniblock, microtee vs miniblock, and LID vs miniblock. Results are summarized and conclusions are drawn based on actual data. Miniblocks lend themselves easily to automated assembly techniques. These automation techniques are discussed, especially as they affect assembly yields and costs.

INCREASE TERMINAL TO PAD-PEEL STRENGTH WITH A STANDARDIZED METALIZATION SYSTEM

Charles J. Trexler and Ernest T. Nicotera, Berg Electronics Division, E. I. Du Pont De Nemours & Company, lnc.

To achieve the standardization of terminal to pad-peel strength, we investigated the variables that influence pad- peel strength. Some of these variables are: the substrates which are either 95% alumina or porcelainized steel; the type of metalization for pads; the base material composition of the terminal that is to be attached to the metallized pad, and the effect of a terminal's "bare edge" vs. a "plated edge". Additional variables are the type of solder flux used and the solder or reflow process being employed. This paper will discuss the interaction of the chemical elements as they apply to the interface of the terminal to the metallized pad. This is of paramount concern for the better this interface is controlled, the more reliable the connection. The use of SEM (Scanning Electron Microscopy) and EDAX (Energy Dispersive Analysis by X-Rays) technology coupled with tensile tests confirmed the type of connection achieved. Environmental conditions such as relative humidity and thermal aging were introduced into the reliability equation. These environmental test results were evaluated as to their influence on a good intermetallic joint between the thermal and metalized conductor pad. The data collected for this study was specific because we were selecting standard components supplied by Du Pont for the micro-electronics industry. Our recommendations for a standardized metalization system will include: the thick-film compositions, the clip-on terminal type and plating, the ratio of terminal pad to terminal width, the optimum soldering or reflow temperature, and the preferred soldering or reflow process. Our recommendations will apply primarily to substrates of 95% alumina. The porcelainized steel data was inconclusive. 110 MICROELECTRONICS SYMPOSIUM AN APPROACH TO A LOW COST, CUSTOM, HERMETIC HYBRID PACKAGE J. R. Sims, P. G. Creter, J. W. Soucy and S. T. Shapiro, Sylvania Systems Group, GTE Sylvania, Inc., Eastern Division, Needham, Massachusetts

An application has resulted in a series of four different metal/ceramic hybrid packages which required no special tooling. The overall process is detailed and depends upon thick film multi-layer processing, solder paste printing, solder reflow, chip and wire assembly techniques, and fluxless solder sealing in a nitrogen atmosphere. Various problems had to be overcome to improve yields and result in a smooth process flow. Specific problem areas encountered and remedied were blisters in the solder seal area, poor temperature resistance of the solder stop, solder ball formation during seal area tinning, poor solder wetting on covers when tinned, and low solder lead adhesion strength. Particular attention was given to establishing criteria for acceptable hermetic seals with high yields. Although the hybrids were designed and built to meet a commercial specification, military specifications and requirements were generally applied. As a consequence, the packages successfully passed leak testing per MIL-STD- 883 and various other requirements according to MIL-M-38510 and MIL-STD-202. The packages were also found to be light weight and reworkable. When evaluated and compared to conventional hybrid packages on a material and labor basis, the new design proved to be competitive in cost. DELIDDING AND RESEALING OF LARGE RESISTANCE SEAM WELD HYBRID PACKAGE ASSEMBLIES Gene A. DiGennaro and Wyatt F. Luce, Westinghouse Electric Corporation, Defense and Electronic Systems Center, Aerospace and Electronic Systems Division, Baltimore, Maryland 21203

In military hybrid applications, the trend in hermetic sealing of large packages is away from solder sealing towards weld sealing. The most common method employs the resistance seam weld technique. A key problem associated with weld sealing is the delid /re seal sequence of operations. Presently, many vendors reluctantly scrap any weld sealed packages which fail. As the complexity and size of hybrid microelectronic packages continue to increase, a level is attained where the package becomes too expensive to be scrapped. It is at this level that the package must be opened, repaired, and hermetically resealed. This paper describes a successful delid/clean/reseal method for weld sealed 1" x 2" metal butterfly packages. Delidding is done by sanding and lapping, and then cutting the lid with a stoppered knife. Dressing and cleaning are required to ensure the packages will be particle free. The new lid is welded directly onto the remaining portion of the original lid. The delid/reseal technique is simple and cost- effective, and results in packages which meet applicable MIL-STD-883 requirements for hermeticity, environmental testing, and PIND testing. MIC PACKAGE USING THICK FILM AND DIRECT BOND COPPER* FOR 100-W L.BAND POWER AMPLIFIER

J. Charles Gioia, General Electric Company, Electronic Systems Division, Syracuse, N. Y.

Based on General Electric's successful experience in implementing the first L-band solid-state radar and having proven its high reliability, a new-generation solid-state radar has been built which makes use of a 100-W MIC amplifier module instead of the original 50 W. This paper deals with the novel features of the package, the concerns which arose in its implementation, and the solutions found which assuage these concerns. PLATINUM/PALLADIUM/GOLD THICK FILMS DECREASE MICROWAVE SOLDER ASSEMBLY COSTS AND IMPROVE RELIABILITY

J. F. Graves, The Bendix Corporation Communications Division, Baltimore, Maryland and M. D. Kline, Westinghouse Electric Corporation Baltimore, Maryland

Certain Microwave Integrated Circuits (MIC's) exhibit surplus gain in operation. This characteristic allows more lossy conductor metalization systems than Au. In these cases, Pt-containing Au metalization having less than approximately .035 ohms per square resistivity is used by itself and in conjunction with Au metalization. This construction allows the use of standard Sn]Pb solder for assembly and eliminates the problems associated with soldering to Au metalization. Dielectric solder dams are used to separate the two conductor materials. The Pt-containing Au metalization can be etched using standard 12/KI etching solutions. Environmental stresses of temperature cycling and humidity cycling do not, affect either the metalization of the solder joints. MICROELECTRONICS SYMPOSIUM 111 MICROWAVE APPLICATIONS OF FERRIMAGNETIC PASTES N. B. Chakrabarti, C. K. Maiti, S. Kal and D. Bhattacharyya, Department of Electronics, Indian Institute of Technology, Kharagpur 721302, India

Thick film ferromagnetic paste (ESL-EX-2000) have been used for the fabrication of delay lines (1,2) and tunable VHF filters (2). But these pastes have not been fully characterized, nor their applications at microwave frequencies examined. This paper reports results of investigations on the development of ferrimagnetic pastes suitable for UHF and microwave components using thick film technique. The electrical and magnetic properties of the ferrite pastes developed have been studied over the range from few MHz to 10 GHz using rectangular spiral inductors at low frequencies, strip and microstrip delay line configuration in the VHF/UHF range and microstrip transmission line setup in the microwave region. The ferrimagnetic thick films are useful in realizing UHF and microwave integrated circuits as they readily permit combination of magnetic and nonmagnetic components on the same substrate. Reciprocal and nonreciprocal microwave components have been realized with these pastes. Special attention has been given to realization of MIC egde guided mode devices as such mode occurring in a wide strip/microstrip transmission line using a ferrimagnetic substrate magnetized perpendicular to the ground plane exhibits unusual broadband behaviour. Egde guided mode isolators have been built completely in thick film technique. Performances of these devices will be described and compared with those realized on YIG/ferrite substrates.

SURFACE ACOUSTIC WAVE RESONATOR FABRICATION AND PACKAGING WITH EMPHASIS ON CONTAMINATION EFFECTS

S. J. Dolochycki, E. J. Staples, J. S. Schoenwald and T. C. Lim, Rockwell International Electronics Research Center, Thousand Oaks, California 91360 This paper describes the major process steps associated with high Q Surface Acoustic Wave (SAW) resonator fabrication. Because of highly sensitive surface effects, which are inherent in SAW resonator devices, both organic and inorganic surface contamination can influence crystal Q, resistance, and most sensitive of all, the operating frequency of the resonator. Packaging is of primary importance for any electrically active or passive device that requires a moisture-free, inert, hermetically-enclosed environment. This is particularly true for the SAW resonator crystal. A low outgassing polyimide compound for die attaching the resonator chip to the base of a hermetic enclosure, is described. After the die attach process, the resonator is hermetically sealed in a moisture-controlled atmosphere by using capacitive discharge resistance weld under high vacuum. A novel hermeticity testing procedure that uses the SAW resonator is described. The low noise characteristics, including short-term and long-term stability, are presented. Potential applications include low noise frequency sources to be used in high frequency communications systems as well as satellite communications systems. EPOXY FABRICATION TECHNIQUES FOR MICROWAVE HYBRID CIRCUITS

Louis P. Hernandez, Miteq Inc., Hauppauge, New York 11787

Although the use of epoxies in manufacturing hybrid microelectronics at VHF frequencies is well established, their use at microwave frequencies is not widely known. We have developed PIN diode attenuators in MIC configurations at 15 GHz and other MIC's (mixers, oscillators, medium-power amplifiers) in the 2 to 4 GHz range. This paper describes some of the epoxy techniques used to produce and modify hybrid MIC's at microwave frequencies. Conductive epoxies have been used to bond both active and passive devices, insulating epoxies to protect active devices from environmental hazards, and sealing epoxies to meet hermetic sealing requirements. When components are thermally sensitive, epoxy bonding is superior to eutectic die attachment techniques because epoxy bonding can be used at much lower temperatures and prevent DC parameter shift. Epoxy can be dispensed by manual, screen printing, or automated methods. The protection afforded by insulating epoxies permits hybrid MIC devices to be moved out of the white rooms to the laboratories, where normal methods can be used to test particular circuits. Thin-film hybrid MIC's can be modified while they are in test fixtures so that the next circuit evaluation can incorporate the new circuit refinements, eliminating costly and time-consuming trial-and-error procedures. In working with epoxies for microwave MIC's, precautions must be taken. Different coefficients of expansion of the materials used may cause failures of MIC bonded components. When environmental factors are neglected (as they too often are), silver migration may present problems. Epoxy techniques provide several advantages over other bonding techniques at microwave frequencies such as higher yield, lower capital equipment costs, shorter training time for assemblers, flexibility in modifying circuits and compatibility with thermally sensitive components. 112 MICROELECTRONICS SYMPOSIUM SUPERIOR PERFORMANCE OF THICK FILM MICROWAVE CIRCUITS IN HIGH POWER APPLICATIONS AND INDUSTRIAL MEASURING CIRCUITS

W. Funk and W. Schilz, Philips GmbH Forschungslaboratorium, Hamburg 2000 Hamburg 54

Film technologies are well established methods for the manufacture of integrated circuits for frequencies up to about GHz. In this frequency thick film circuits exhibit specific advantages which are well known. In order to test whether thick film can be although applied in a typical microwave region we have investigated transmission lines, components and lumped elements for frequencies up to 16 GHz. Except for a slight increase of attenuation the electrical behaviour of thick film circuits equals that of thin film MIC's. Moreover the power capability of MIC's can be remarkably increased by applying thick film multilayer techniques, e.g. the sparkling level of a phase shifter can be increased by a factor of 10, by overprinting the structure with a dielectric. Additionally the greater mechanical stability as compared to thin film structures is advantageous in industrial measuring systems, where open structures used as applicators are in direct contact with the material to be measured. Here, the structure may have to withstand aggressive environments and abrasive forces. Typical examples of microwave components and selected applications will be discussed.

AUTOMATIC ASSEMBLY AND CHIP COMPONENTS FOR THIN FILM CONSUMER ELECTRONIC PRODUCTS IN JAPAN

Sei-ichi Denda, Sanken Electric Co., Saitama, Japan and Akira Ikegami, Hitachi Ltd., Tokyo, Japan

Newly designed both active and passive chip components to be mounted on printed circuit board were developed and have become popular for Japanese consumer products. They aim at reducing total dimensions, especially the thickness of an electronic equipment, and make an efficient automatic assembling process possible with solder bonding. Mini-mold IC and transistors in a simple plastic package are replacing conventional semiconductor chips for hybrid IC and even discrete transistors. Leadless MELF components were designed for diodes, resistors and capacitors, all in a standard dimension. They are used in an unique automatic system. The use of these chip components reduces the thickness of portable equipments drastically with the help of flat mechanical parks. PROGRESS ON HYBRID TECHNOLOGY IN ITALY

R. Dell'Acqua and F. Forlani, Magneti MarellL Systems and Electronics Division, 27100 Pavia (ltaly)

In the last two years (1977, 1978) the Italian market has been expanded over 20% per year and the same trend is forecastable for the current and next years. Some new manufacturers have begun an operation in this field especially in 1978; however, the real expansion of the market has been supported by very few companies, which have served the booming requirements of the automotive industries and, to a lower extent, of the telecommunications companies. A few examples of realizations in these fields are presented. They show that thick-film technology has dominated the scene of the circuits for automobiles, while in telecommunications thin and thick-films are still competing. Encapsulated and microencapsulated active devices continue to be the choice to a great extent in the hybrid circuits presently manufactured, due to the positive results in reliability accumulated in the past years. Nevertheless, the higher complexity in the circuits merged with requirements of miniaturization, the larger volume per circuit needed in some application field and the increase in the use of microcircuits in biomedics and military applications are forcing the major Italian manufacturers to introduce more and more the use of naked chips, either chip-and-wires or flip-chips. In addition to these industrial developments, significant works on thick-film R & D have been carried out about the studies of conduction mechanisms in screen-and-fired resistors and on possible new fields of application. The main effort is presently directed to the development of thick-film sensors. THE EFFECT OF NITROGEN AND NITROGEN-HYDROGEN ATMOSPHERES ON THE STABILITY OF THICK FILM RESISTORS

Martin V. Coleman, Standard Telecommunication Laboratories Ltd., Harlow, England

Hydrogen has been found to reduce both bismuth ruthenate, present in Du Pont 'Birox' resistors, and ruthenium dioxide causing increases in resistance values of thick film resistors as the conducting network is destroyed. The MICROELECTRONICS SYMPOSIUM 113 resistors based upon ruthenium dioxide are much more susceptible to change than those based upon bismuth ruthenate. A protective overglaze over the resistor can in some cases prevent this reduction occurring but after laser trimming the resistor is exposed around the trim and subject to attack. Changes in resistance in oxygen-free atmospheres have been found to be greater than in air at elevated temperatures for unglazed resistors and the loss of oxygen from the resistor is suggested to be the mechanism. A model is established to explain the raying resistor drifts based upon a combination of varying resistor drifts based upon a combination of stress relaxation, which obeys a cube root of time law, oxygen diffusion out of the resistor, based upon a square root of time law, and hydrogen attack which is linearly time dependent. EFFECTS OF DOPANTS ON THE SHEET RESISTIVITY OF CADMIUM OXIDE THICK FILM RESISTORS

Shen-Li Fu and Gi-Chang Lin, Department of Electrical EngineeHng, National Cheng Kung University, Tainan, Taiwan Republic of China

The effects of Dopants as well as the firing atmospheres on the sheet resistivity of CdO thick film resistors have been studied. The dopants include mixed metallic oxides and ion-implanted B 3/ and ps/ ions. The sheet resistivity will be increased when metallic ions of higher valency (Than Cd 2/) are introduced into CdO Resistor, and will be decreased if lower valency metallic ion is introduced. The sheet resistivity will also be increased when fired in N than in open air condition. The reason that sheet resistivity is decreased can be attributed to the valence induction when lower valency metallic ion is added, while the increase in sheet resistivity can be attributed to the introduction of recombination centers by adding higher valency metallic ions into the deficit CdO Resistor. The increase in sheet resistivity when fired in oxygen-reduced atmosphere can be taken as another evidence of considering CdO as a deficit nonstoechiometric semiconductor. CAPABILITIES AND LIMITS OF CERAMIC CHIP CARRIER COMPUTER MODEL FOR THERMAL AND MECHANICAL BEHAVIOUR

Frederic L. Rossi, Thierry E. Vernier and Christian M. Val, Thompson-CSF, Department Circuits Hybrides, B.P. 10, 91401 Orsay, France

The need for LSI circuits leads the manufacturers of hybrid microelectronics to look for tested and burned-in components, in order to obtain high output yield. In our company, we started a working program since 1977 on feasibility of soldering and characterization of micropackages of the chip carrier type and T.A.B. Thermal and mechanical characteristics of the system: chip carrier, solder, substrate are presented and developed. A thermal model was achieved for several configurations. The experimental value of thermal resistance was obtained through infra red measurements and VBE Transistor values. We also investigated the effects of the area of the soldering pads, the soldering or epoxy mounting, and the number of the substrate layers. The soldering of the chip carrier back face on alumina leads to the lowest overall thermal resistance: 12 K/W compared to 19 K/W for back face glued. Theoretically and practically the most sensitive problem is the mechanical behaviour of the overall structure. We developed a computer model of this behaviour for the following configuration: Alumina substrate/chip carrier; Porcelainized steel/chip carrier; Epoxy printed circuit/chip carrier. This model allowed us to find the limits of thermal stresses under life cycle simulation, and we are now verifying its validity. STANDARDIZATION AND CUSTOM HYBRID MICROCIRCUITS Daniel D. Zimmerman, The Johns Hopkins University, Applied Physics Laboratory, Laurel, Maryland

Two years ago, the ISHM symposium theme was, "A Maturing Technology." Can hybrid microeleetronics be considered fully matured without standardization? Last year the symposium theme was, "The Expanding World of Microelectronics." Will this expansion be enhanced by standardization? Since custom circuit design applications are the basis for a large sector of the hybrid microcircuit business, it is not likely that these circuits will be standardized nor will the processes being applied in their production. However, when efforts on 114 MICROELECTRONICS SYMPOSIUM

standardization are focused on packages, substrates, components and interconnections, an enthusiastic response has been experienced. Economic forces suddenly can be seen coming into view in support of standards for hybrid microcircuits. Specific efforts which ISHM has taken to develop these standards are addressed in this paper. Status in current documents, plans for future efforts, and coordination with other societies in rehted areas are also included. The ISHM Technical Workshop method of collecting a consensus data base for a standard is also discussed. HYBRID MICROELECTRONICS SUBCOMMITTEE OF THE MANUFACTURING TECHNOLOGY ADVISORY GROUP-AN OVERVIEW

Joseph L. Ansell, U.S. Army Electronics Research and Development Command, Harry Diamond Laboratories, Adelphi, MD 20783

The Department of Defense sponsors a Manufacturing Technology Program to reduce the costs of defense systems. Projects conducted under the program are aimed at developing or improving manufacturing processes, methods, techniques, and equipment. This report summarizes the operation of that part of the Manufacturing Technology program and of the Manufacturing Technology Advisory Group that is related to hybrid microelectronics. Typical past, present, and future efforts are presented, as is the interface between the Department of Defense and industry.

TEMPERATURE CYCLING OF HIC THIN FILM SOLDER CONNECTIONS

H. N. Keller, Bell Telephone Laboratories, Incorporated, 555 Union Boulevard, Allentown, Pennsylvania 18103

Interconnecting Hybrid Integrated Circuits (HIC's) is one of many applications for soldering in the electronics industry. However, intermetallic compound formation and cyclic fatigue have been reported as factors which can limit solder joint reliability. Identification of intermetallic compounds formed during constant temperature aging and how they affect HIC thin film solder joint reliability has been previously reported. How temperature cycling affects solder joint strength, and whether intermetallic formation or cyclic fatigue is present are described here. The investigation consisted of (1) preparing test circuits using clip-on terminals, a fixed volume of 60Sn-40Pb solder, and resistor-capacitor (RC) and resistor HIC terminations, (2) temperature cycling free standing circuits, (3) measuring solder bond strength, and (4) analyzing weak bond interfaces and solder joint metallographic cross-sections by SEM-EDAX and EMP. Solder joint strength in the range of 5-10 pounds after 1000 temperature cycles from -40 to 130 C is comparable to previous measurements after 1000 hours at 150 C for both resistor and RC type terminations. However, terminations after pull testing show a different failure mode after temperature cycling than after constant temperature aging. Interfacial fractures after temperature aging are related to intermetallic formation. Bond degradation during temperature cycling again appears to result from intermetallic compound formation, but there also appears to be weakening at the interface between the Pd and underlying films. Regardless of this failure mode difference, joint strength, and the 2-4 pound reduction below initial values for free-standing circuits, meet requirements. These results indicate that the thermal expansion coefficients of these terminal-solder-termination-ceramic materials are sufficiently matched to prevent excessive thermal strains.

EFFECT OF SURGE VOLTAGES ON THICK FILM RESISTORS Yutaka Saitoh, Yukio Katsuta and Keiji Suzuki, Nippon Electric Company Ltd., Devices Department, Transmission Division

This paper describes the effect of surge voltages (ex. induced lightning and switching surges) on thick film resistors. Two kinds of phenomena are observed by applying surge voltages (rise time; 0.5-100 sec, decay time-3000 usec and applied peak surge voltage: 50 volts-10 K volts) onto thick film resistors. One is dominant in low resistivity (< K ohms/square) thick film resistors, where permanent change in resistivity is positive. It is brought about by surge voltage discharge and microcracks growth at the terminal end of a laser trimmed kerr. The other is dominant in high resistivity ( 10 K ohms/square) thick film resistors, where permanent change is negative. This phenomenon seems to be brought about by forming current paths inside thick film resistor materials. Relations between surge voltages and 1) sheet resistivities, 2) resistor materials, 3) resistor geometries, 4) trim configurations and 5) aging characteristics, were investigated. MICROELECTRONICS SYMPOSIUM 115 MATERIALS AND BONDING CONSIDERATIONS FOR THIN-FILM GOLD-BEAM HYBRIDS

Dr. Richard A. Glass, Dr. Robert D. Wales and Dr. Henry W. Lavendel, Lockheed Palo Alto Research Laboratory, Palo Alto, California 94304

Lockheed Missiles & Space Company (LMSC) maintains thin and thick film facilities for in-house fabrication of hybrid circuits, including substrate and assembly facilitaties for making thin-film gold-beam-lead hybrids of unique design, A number of considerations involving materials and structures have been discovered that impact quality control in general and bonding reliability in particular, which have led to the development of special tools and techniques for testing and failure analysis. The principal techniques have been pull-strength and microhardness testing methods, which are routinely applied to hybrid production lots. Principal failure problems, which have been the subject of intensive external and destructive-physical analyses, are brittle facture of gold beams, formation of Au-Si eutectic at metallization-to-chip windows, and contamination of bonding surfaces by Vaseline and other contaminants.

MOISTURE EFFECT ON HYBRIDS CONTAINING CMOS CIRCUITS Charles G. Messenger, Rome Air Development Center, Griffiss Air Force Base, NY, Robert E. E. Sulouff, Microelectronics Engineering Corporation, P.O. Box 1209 Auburn, AL, and Dennis Greeley, Martin Marietta Aerospace, Orlando, FL

This paper reports the technical approach and results to-date on an effort to correlate moisture levels in hybrid microelectronic packages to the reliability of CMOS devices. The effects of water contamination has been a topic of intense discussion in the current literature. Failures due to corrosion have typically been the most dramatic and obvious. The more subtle effects of water molecules on the electrical parameters has been difficult to quantify. This paper discusses experimental efforts to evaluate hybrid packages that have been "filled" with different amounts of water vapor. The values of 500, 1000, 5000 and 10,000 ppm water have been sealed into one inch flat packs with circuitry mounted on standard thick film substrates. A CMOS LSI with additional capacitors and test transistors on the chip were evaluated along with standard RCA 4001 CMOS and 4049 CMOS devices. A special environmental cycle was used to accelerate the effect of moisture. The packages were held at 125C without bias for 24 hours to liberate the internal water vapor. The packages were then cooled to -35C to freeze out the water and warmed up to 2 C with bias applied. The total cycle described being 48 hours in duration. The parts were cycled 100 times as an accelerated testing technique. Insufficient data existed at the time of the writing of this paper to describe the results of this accelerated testing. The use of moisture sensors as a technique for moisture analysis was an important phase of the technical effort. Oxide sensors were evaluated and used to correlate the sealed-in moisture values with mass spectrometer measurements. The moisture sensors were calibrated and then sealed inside of each package. The sensors indicated groupings according to the sealed-in moisture levels. Gross leaking packages were detected with the sensor by an indicated change in the sensor readings. A correlation was developed between the room temperature sensor reading and the method 1018 water vapor (mass spectrometer) measurement. Insufficient data and sample size were available at the time of writing to provide an accurate correlation. Evaluation of the experimental data to-date has indicated some trends which are related to higher failures occurring in the higher moisture level packages.

CONTROL OF SEMICONDUCTOR FAILURES CAUSED BY CRATERING OF BONDING PADS Vidyadhar S. Kale, Teledyne Microelectronics Division, Los Angeles., California

Cratering of semiconductor bonding pads is an important problem that has received less attention than it deserves in literature on microelectronics. Cratering can often be serious because there is no visual indication of the presence of such craters when they occur. Diagnosis of the problem becomes possible only when the overlying metallization is etched and the silicon underneath revealed. This investigation deals with the phenomenon of cratering and establishes methods of controlling the bonding process to eliminate current leakage or threshold voltage type failures which are caused by such fractures. In the preliminary discussions, various causes of oxide fractures are outlined. Some theoretical analysis is then performed to calculate contact stresses between the wire and the semiconductor bonding pad. The classical Griffith theory of brittle fracture is invoked to determine what type of forces would be responsible for creation of fractures in silicon. The possibility of die probing as a cause of fracture inducing microcracks is also discussed. 116 MICROELECTRONICS SYMPOSIUM Major experimental work performed in this study consisted of several thousand ultrasonic bonds made on different kinds of dice with controlled variations in major lead bonding parameters. After bonding the parts were carefully etched and the number of pads with craters were counted for each group. The final results were analyzed to determine the effect of each parameter. Additional tests performed to verify the above results and establish optimum bonding conditions indicated the presence of a definite resonance associated with the transfer of ultrasonic power to the bonding site. SEM photographs of major die types were obtained and compared against their performance in the experiments described earlier. It was noted that aluminum thickness and cratering had an inverse relationship. In conclusion a set of guidelines is prescribed to establish optimum bonding parameters and substantially reduce semiconductor failures caused by cratering.

A LARGE HYBRID ELECTRO-OPTICAL ARRAY

Samuel Goldfarb, Princeton, New Jersey, Consultant to Itek Corporation, and Donald Colvin, Optical Systems Division, ltek Corporation, Lexington, Massachusetts

Electro-optical arrays designed to replace film in large-format reconnaissance systems exceed the size limitations of monolithic devices. Several detector chips must be combined to obtain the required field and resolution. The chips must be assembled with photosites in precise relationship to maintain spatial coherence without undesired gap or overlap. Photosites must be nearly coplanar to reduce focus requirements and, finally, the entire assembly must be packaged in a hermetic container with an optical quality window. To satisfy these requirements, a focal plane was developed to cover a 5 inch field with 10240 photosites. The array consists of 5 large CCD chips precisely mounted on a multilayer, thick film printed alumina substrate. Chip-to-chip mounting accuracy provides photosites which are colinear, coplanar and evenly spaced within 0.2 mil (0.0002 inch). Materials, chosen for thermal stability, maintain the required accuracy. The assembled hybrid substrate is hermetically sealed in a custom ceramic package, 2 6.4 inches long with 113 leads. Thermal stresses are minimized by using an alumina body which matches the substrate coefficient of thermal expansion (CTE) and closely approximates the sapphire window CTE. This paper describes the system requirements for chip mounting and packaging and the successful design solutions. Alternative designs and trade-offs are included as well as optical chip alignment techniques and tooling, chip mounting and wire bonding, hermetic package design, fabrication and sealing, accuracy and stability tests. TARNISH GROWTH ON SILVER FILM CONDUCTORS AND ITS RELATION TO POTENTIAL RESISTOR FAILURE IN TELEPHONE CENTRAL OFFICES

F. N. Fuss, R. F. Leach, and W. H. Yocom, Bell Telephone Laboratories, Incorporated, 555 Union Boulevard, Allentown, Pennsylvania 18103

Field failures from sulfiding of silver film conductors prompted studies of tarnishing under laboratory and field conditions. A new, accurate method was developed to determine the sulfiding rate from the resistance change of thin silver films. Results show large variations between and within central office locations, and a strong dependence on protective coatings, sulfur concentration and ambient air flow rates. HYBRID PROGRAMMABLE DRIVER CIRCUIT FOR TESTING HIGH SPEED COMPUTER PRINTED CIRCUIT BOARDS P. L. Moran, Loughborough University of Technology, Loughborough, Leicestershire, U.K. and G. Catlow, International Computers Limited, Wenlock Way, West Gorton, Manchester, U.K.

Computer system p.c.b, assemblies can be tested in a variety of ways and one of the methods most commonly adopted is to exercise the board functionally using specialized test equipment which applies and monitors signals entering and leaving the board under test (b.u.t.). It is important therefore that the test equipment should appear electrically similar to the circuitry to which the board will eventually be connected. Each edge finger of the board under test could, depending upon the particular circuit be either an input or an output, and hence a facility should be provided to switch the output of the driver circuit into a state that does not load the b.u.t. In order that the speed of operation shall be as high as possible and as for the particular test equipment described, several hundred drivers are required, the final assembly should be as small as possible. The relatively low quantity of driver circuits required prohibits the design of a custom integrated circuit and so a hybrid approach has been investigated. The paper describes the design of a circuit capable of carrying out these tests on boards containing both ECL MICROELECTRONICS SYMPOSIUM 117 and TTL devices. The final assembly for each driver is a low cost 24 pin dual-in-line plastic encapsulated module constructed using thick film hybrid techniques. A CHEMICAL METHOD FOR THE REMOVAL OF RTV CONFORMAL COATINGS James E. Ireland, Candia S. Schimelfenig, Micro-R el, Division ofMedtronic lnc.

With the increasing use of silicone RTV conformal coating in the hybrid and general semiconductor industries, the need arises for a viable method for removing such coatings to allow for device repair and/or failure analysis. The report outlines the successful development and testing of a chemical method for removing a specific RTV encapsulant, Dow Corning QCF3-6550 from a thick film hybrid circuit. The decapsulation procedure is outlined and electrical and reliability data are presented comparing treated and untreated test ckcuits.

SOLVENT REMOVABLE COATINGS FOR CONTAMINANT PROTECTION OF HYBRID MICROCIRCUITS

Bernard L. Weigand and James J. Licari, Rockwell International Corporation, Electronic Devices Division, Anaheim, CA and Edward J. Morrisey, Air Force Materials Laboratory Systems Support Division, Wright-Patterson Air Force Base, OH

Low to intermediate molecular weight uncrosslinked silicones and halo carbons soluble in Freon TF, toluene, or xylene were evaluated as particle immobilizing coatings for hybrid microcircuits. These coatings can easily be removed by a "hands-off" process for circuit rework. Based on physical, chemical, thermal and electrical charac- terizations of the coating candidates, a silicone block copolymer and a formulation of this copolymer with a halocarbon polymer were selected for further evaluations. A hybrid test circuit containing a variety of devices selected for their sensitivity to surface contamination was designed for this evaluation. Coated test circuits, one- half of which were seeded with conductive particles, and controls were serially subjected to mechanical shock (1500 g) and constant acceleration (10,000 g) in the Y2 axis followed by high temperature storage (1000 hours/150 C). A second set of coated hybrids and controls were subjected to burn-in (1240 hours/125 C). The electrical parameters of all devices, with the exception of Pd/Ag/Pd oxide thick film resistors, remained within the specification requirements on completion of the tests. The changes in the coated thick film resistors were similar to those in the uncoated controls. No wire bond failures occurred in any of the test hybrids. PIND testing of the test circuits seeded with particles showed all of the particles to be immobilized. PIND testing of the control circuits showed two of the sixteen circuits contained particles generated during the test sequences.

ZERO FIRING SHRINKAGE CERAMIC SUBSTRATES

E. Frederick Borchelt and Edward J. Smoke, Rutgers University ofEngineering, Department of Ceramics, 'scataway, NJ

An electrically insulating ceramic substrate has been developed which possesses firing shrinkage and moisture absorption values of less than one percent. A lead alumino-silicate compositions was utilized, to which additions of wollastonite were made. Mass production techniques were employed in fabricating substrates with reproducible properties. Analytical tools such as the SEM, differential thermal analysis and X-ray diffraction helped to identify the fundamental reactions and mechanisms. The characteristic properties were determined for each of three compositions that were formulated. THE SIGNIFICANCE OF GLASS TRANSITION TEMPERATURE ON ELECTRICALLY CONDUCTIVE EPOXY RESINS IN HYBRID MICROELECTRONICS

Frank W. Kulesza and Thomas F. Saunders, Epoxy Technology, lnc., 14 Fortune Drive, Billerica, MA 01821

For thirteen years now, electrically conductive gold and silver filled epoxies have been steadily replacing eutectic bonding of chips in hybrid microelectronics. Along with describing some of the advantages of epoxies, this paper 118 MICROELECTRONICS SYMPOSIUM

will illustrate one of the outstanding characteristics of this family of bonding agents; the glass transition temperature. This thermodynamic and thermomechanical characteristic of epoxy resins is defined as the midpoint of the temperature region where the properties of epoxy resins change from those of a glassy state to a rubbery state. Furthermore, this paper illuminates some of the mystique surrounding Tg, as glass transition temperature is usually abbreviated. Finally, this paper will explain how this sensitive property of epoxies, Tg, can be used in quality control of their manufacture.

RECENT ADVANCES IN LASER HOLE DRILLING: MANUFACTURING EFFICIENCIES AND COST REDUCTIONS IN HYBRID MICROCIRCUIT PRODUCTION James E. Byrum, Spec Industries, Inc., San Marcos, California

The use of laser drilling in the hybrid microcircuit technology has been relegated in the past, for the most part, to low volume circuit manufacture. The reason for this has been the high cost per drilled hole and poor hole quality when compared to holes poached in unfired alumina. However, a recent advance in laser equipment technology has enabled CO2 laser drilling to be more cost effective approach while at the same time significantly improving hole quality. When the resulting improved performance is coupled with the accuracy and versatility inherent in laser processing, it now becomes possible to utilize this technique to fabricate large multi-part arrays to reduce over-all manufacturing costs. In addition, existing microcircuit processing equipment can be utilized with parts made from this technique, normally with little or no modification. This paper describes the basic concepts of the new technique. Also, presented are the circuit layout design factors needed to best utilize this method and other parameters influencing hole cost, position accuracy and part quality. MATERIALS AND CURING CHARACTERISATION OF CONDUCTIVE EPOXIDE ADHESIVES

David M. Shenfield, Standard Telecommunication Laboratories Ltd., Harlow, England

Results are presented of work aimed at a better understanding of the curing mechanisms of conductive organic resin adhesives, their process sensitivity and likely behaviour during life. High performance liquid chromatography and gas chromatography/mass spectrometry were the analytical techniques used to determine the chemical composition, important for quality control, of electrically conductive chip-attach adhesives. A method for monitoring on a routine basis the hydrolysable chlorine content of incoming epoxide adhesives has been established. Data obtained indicates that chloride levels vary considerably from manufacturer to manufacturer, and batch to batch. Measurement of glass transition temperature as a function of curing schedule was shown that in certain cases manufacturers' recommended curing schedules are inadequate to fully cure the material. Measurements of volume resistivity relative to curing schedule have indicated cure dependence. The effects of curing schedule on adhesion strength have been examined using a pull-peel test method, based on the Sergent method proposed for solder joints. International Journal of

Rotating Machinery

International Journal of Journal of The Scientific Journal of Distributed Engineering World Journal Sensors Sensor Networks Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014

Journal of Control Science and Engineering

Advances in Civil Engineering Hindawi Publishing Corporation Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014

Submit your manuscripts at http://www.hindawi.com

Journal of Journal of Electrical and Computer Robotics Engineering Hindawi Publishing Corporation Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014

VLSI Design Advances in OptoElectronics International Journal of Modelling & International Journal of Simulation Aerospace Navigation and in Engineering Observation Engineering

Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2010 http://www.hindawi.com Hindawi Publishing Corporation http://www.hindawi.com Volume 2014

International Journal of International Journal of Antennas and Active and Passive Advances in Chemical Engineering Propagation Electronic Components Shock and Vibration Acoustics and Vibration

Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014