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The reliability, testing and evaluation of hybrid microcircuits
World Abstracts on Microelectronics and Reliability fined electron-hole liquid (EHL) in Ge. We find that the change in drop density with uniform stress is insufficient to explain the experimental result. However, we find that the strain gradient in the well acts to compress the liquid 8. T H I C K -
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sufficiently to explain the observed density increases. Densities of twice the equilibrium value can be easily obtained for large enough drop size, but the density should vary by < 10% if the drop radius is < 100 pm.
COMPONENTS,
HYBRID
CIRCUITS
MATERIALS
Economics of thick and thin film hybrid production in Europe. D. BOSWELL and D. S. CAMPBELL. Electrocomp. Sci. Technol. 4, 219 (1977). This paper is a report of a discussion panel held at the First European Conference on Hybrid Microelectronics, concerning the Economics of Hybrid Production. Figures were presented at the discussion showing the sizes of the markets in the U.S.A. and in Europe, demonstrating the percentage of total hybrid markets associated with thin film technology and also the percentage of the market associated with hermetically packaged circuits. It was shown that the growth rate in hybrid technology is similar to that predicted for integrated circuits, a result which can be explained in terms of the interconnection facility which hybrid technology offers. The reliability, testing and evaluation of hybrid microcircuits. A. H. GEORGE. Electrocomp. Sci. Technol. 4, 213 (1977). Reliability aspects of Hybrid Microcircuits are considered, including a prediction model illustrating the detail knowledge of the technology and application necessary. Circuit, part and element data is presented for two different test circuits. Use is made of predicted circuit failure rates to establish an electrical endurance test programme together with the thermal stress levels likely to generate some failures in an acceptable time. Results of testing the circuits at more than one temperature are presented, evaluated and compared with prediction. Failure analysis enables the performance of add-on parts, circuit elements and bonds to be assessed. A second series of test circuits confirms an improved bonding system. The usefulness of reliability modelling prior to endurance testing is justified together with some degree of thermal overstress.
Characterization of thick film capicitors. Y. LERoY, M. DESCAMPS and M. VERNET. Electrocomp. Sci. Technol. 4, 125 (1977). Teaching activities of the "Institut Universitaire de Technologie de Lille" (France) were previously reported The present paper reports measurement results obtained by students during their last training period for about a hundred capacitors made with commercial dielectrics (EMCA CDP 400, EMCA CDP 2000, and ESL K 1000). We examine the following points: reproducibility of capacitors during fabrication, correlation between electrical parameters of components and firing conditions, measurements of capacitiance and loss factor between 10 kHz and 20 MHz for temperatures ranging from 20°C to IO0°C.
A new concept in calculation of thick film resistors. G. STECHER. Electrocomp. Sci. Technol. 4, 163 (1977). Because of interaction of resistor and conductor material and variation of film thickness due to different resistor geometries, square resistance becomes a function of resistor length and width. Additional to the square resistance one paste parameter or two parameters must be introduced if the influence of both length and width on the square resistance is to be taken into account. From resistance measurements of a test pattern all paste parameters can be calculated as numerical functions of resistor length by a computer programme using the method of least squares. Beside the layout of thick film resistors, the data are suitable to give a computer plot of square resistance in relation to length and width. This representation can play an important part in paste evaluation and process control. It shows at a glance what relationship will be present with various combinations of conductor and resistor materials or by changed process conditions. Alloy element additions to gold thick film conductors: Effects on indium/lead soldering and ultrasonic aluminum wire bonding. S. J. HOROWITZ,D. J. GERRY and R. E. COTE. Solid St. TechnoL p. 47 (January 1978). Ultrasonic aluminum wire bonding and lead attachment with indium/ lead solders are common techniques for connecting to gold thick film conductors. In accelerated life tests at elevated temperatures, solid state reactions occur which degrade bond or joint integrity. This paper focuses on the changes in these reactions and in interconnection performance that occur when an alloying element is added to the gold thick film conductor. The ultrasonic aluminum wire bonding performance of a state-of-the-art thick film gold conductor and similar materials containing small amounts of an alloying element are compared. The effect of elevated temperature storage on wire bond resistance has also been determined. Wire bonds on unalloyed controls exhibit large increases in electrical resistance, while the electrical resistance of wire bonds on alloyed metallizations remains constant. An optimum level of alloy element addition has been determined through consideration of initial pull strength and ease of bonding. The effects of alloy element additions on 50 In-50 Pb soldering have been studied for one level of additive. The rate of intermediate layer formation and the rate of loss of peel strength of soldered joints are compared for a modified gold conductor and an unmodified control. Functional test results are supported by optical and scanning electron microscopy and x-ray analysis of the interface metallurgy. A model for the effects of alloy element addition on interface reactions is discussed.
AND
THIN-FILM AND
493
sufficiently to explain the observed density increases. Densities of twice the equilibrium value can be easily obtained for large enough drop size, but the density should vary by < 10% if the drop radius is < 100 pm.
COMPONENTS,
HYBRID
CIRCUITS
MATERIALS
Economics of thick and thin film hybrid production in Europe. D. BOSWELL and D. S. CAMPBELL. Electrocomp. Sci. Technol. 4, 219 (1977). This paper is a report of a discussion panel held at the First European Conference on Hybrid Microelectronics, concerning the Economics of Hybrid Production. Figures were presented at the discussion showing the sizes of the markets in the U.S.A. and in Europe, demonstrating the percentage of total hybrid markets associated with thin film technology and also the percentage of the market associated with hermetically packaged circuits. It was shown that the growth rate in hybrid technology is similar to that predicted for integrated circuits, a result which can be explained in terms of the interconnection facility which hybrid technology offers. The reliability, testing and evaluation of hybrid microcircuits. A. H. GEORGE. Electrocomp. Sci. Technol. 4, 213 (1977). Reliability aspects of Hybrid Microcircuits are considered, including a prediction model illustrating the detail knowledge of the technology and application necessary. Circuit, part and element data is presented for two different test circuits. Use is made of predicted circuit failure rates to establish an electrical endurance test programme together with the thermal stress levels likely to generate some failures in an acceptable time. Results of testing the circuits at more than one temperature are presented, evaluated and compared with prediction. Failure analysis enables the performance of add-on parts, circuit elements and bonds to be assessed. A second series of test circuits confirms an improved bonding system. The usefulness of reliability modelling prior to endurance testing is justified together with some degree of thermal overstress.
Characterization of thick film capicitors. Y. LERoY, M. DESCAMPS and M. VERNET. Electrocomp. Sci. Technol. 4, 125 (1977). Teaching activities of the "Institut Universitaire de Technologie de Lille" (France) were previously reported The present paper reports measurement results obtained by students during their last training period for about a hundred capacitors made with commercial dielectrics (EMCA CDP 400, EMCA CDP 2000, and ESL K 1000). We examine the following points: reproducibility of capacitors during fabrication, correlation between electrical parameters of components and firing conditions, measurements of capacitiance and loss factor between 10 kHz and 20 MHz for temperatures ranging from 20°C to IO0°C.
A new concept in calculation of thick film resistors. G. STECHER. Electrocomp. Sci. Technol. 4, 163 (1977). Because of interaction of resistor and conductor material and variation of film thickness due to different resistor geometries, square resistance becomes a function of resistor length and width. Additional to the square resistance one paste parameter or two parameters must be introduced if the influence of both length and width on the square resistance is to be taken into account. From resistance measurements of a test pattern all paste parameters can be calculated as numerical functions of resistor length by a computer programme using the method of least squares. Beside the layout of thick film resistors, the data are suitable to give a computer plot of square resistance in relation to length and width. This representation can play an important part in paste evaluation and process control. It shows at a glance what relationship will be present with various combinations of conductor and resistor materials or by changed process conditions. Alloy element additions to gold thick film conductors: Effects on indium/lead soldering and ultrasonic aluminum wire bonding. S. J. HOROWITZ,D. J. GERRY and R. E. COTE. Solid St. TechnoL p. 47 (January 1978). Ultrasonic aluminum wire bonding and lead attachment with indium/ lead solders are common techniques for connecting to gold thick film conductors. In accelerated life tests at elevated temperatures, solid state reactions occur which degrade bond or joint integrity. This paper focuses on the changes in these reactions and in interconnection performance that occur when an alloying element is added to the gold thick film conductor. The ultrasonic aluminum wire bonding performance of a state-of-the-art thick film gold conductor and similar materials containing small amounts of an alloying element are compared. The effect of elevated temperature storage on wire bond resistance has also been determined. Wire bonds on unalloyed controls exhibit large increases in electrical resistance, while the electrical resistance of wire bonds on alloyed metallizations remains constant. An optimum level of alloy element addition has been determined through consideration of initial pull strength and ease of bonding. The effects of alloy element additions on 50 In-50 Pb soldering have been studied for one level of additive. The rate of intermediate layer formation and the rate of loss of peel strength of soldered joints are compared for a modified gold conductor and an unmodified control. Functional test results are supported by optical and scanning electron microscopy and x-ray analysis of the interface metallurgy. A model for the effects of alloy element addition on interface reactions is discussed.