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Computer applications to the hybrid microelectronic circuit design
214
WORLD
ABSTRACTS
ON MICROELECTRONICS
sium, October-November (1972), p. 2-B-4-1. Monolithic IC manufacturers have employed automatic test systems (ATS) successfully for the past several years. Hybrid circuit manufacturers have been employing such systems relatively recently and may not have attained the same level of success. This paper has made an attempt to investigate that point. T h e paper presents some helpful suggestions for justifying ATS, their selection criteria and examples of their capabilities. The author also presents the results of a nation-wide survey of the use made of automatic test systems by various hybrid circuit manufacturers. A yield analysis m o d e l for hybrid microelectronie circuits. A. LEw. Proceedings I S H M Microelectronics Symposium, October-November (1972), p. 2-B-3-1. Correct yield analysis and projection are paramount to profitable manufacture in today's competitive climate. Yields must be carefully projected in order to generate accurate cost estimates at the proposal stage, and yield attrition must be controlled during the production phase in order to maintain profit levels and schedules. This paper delineates the process flow for various hybrid microelectronic fabrication techniques and develops a mathematical model for the calculation of yield accumulation. T h e model defines the impact of accumulating yield attrition on sequential process steps in terms of labor and material costs. The expressions used in the mathematical model are designed to make it readily adaptable to computerized calculations and to the analysis of more complicated sequential processes.
Computer applications to the hybrid m i c r o e l e c tronic circuit design. V. M. SHUKLA. Proceedings
1SHM Microelectronics Symposium, October-November (1972), p. 2-B-5-1. Computer application in the field of the hybrid cirouit design is described in this paper. The computer has application in each of the following four prime areas of hybrid design: (1) package selection; (2) film resistor design; (3) substrate layout design; and (4) artwork generation. An algorithm used in developing a computer program for package selection for hybrid circuits is described. Resistor design computer program is also discussed. The computerized system flow diagram is presented to illustrate how the computer aids in substrate layout design and generation. Finally, the overall flow chart is presented to discuss computeraided design, and to give complete explanation of the computer as an aid and its application in the hybrid circuit design.
Characterization of a thick-film resistor conduction m e c h a n i s m . A. B. USOWSKI and A. J. VAN ZEELAND. Proceedings I S H M Microelectronics Symposium, October-November (1972), p. 2-A-2-1. A model of the conduction mechanism in a transition metal thickfilm resistor was generated using an experimentally determined relationship between voltage coefficient of resistance and sheet resistivity at low voltage stresses. The equation derived suggests a resistor conduction mechanism of an ohmic d e m e n t in parallel with a field
AND
RELIABILITY
dependent dement. The resistance vs. voltage characteristics over a range of temperatures were also investigated to isolate temperature dependency in the model. A n i n n o v a t i o n i n gold paste. B. R. SMITH and R. L. DIETZ. Proceedings I S H M Microelectronics Symposium, October-November (1972), p. 2-A-5-1. A new glassfree gold paste composition is described and compared with the conventional (fritted) gold paste in bonding mechanisms and properties. Alumina adhesion strengths were measured from two to five times greater than that of conventional golds. Adhesion to beryllia was comparable to Moly M n at about 9000 psi. The absence of a glass thermal barrier at the ceramic interface results in a 20-30 per cent increase in thermal conductivity in a D I P alumina package. The significantly lower thermal resistance of the chip bond allows better utilization of the thermal properties of BeO as well as more efficient use of heat sinking in higher power applications. The T C bondability was shown to be improved, more consistent, and less sensitive to gold thickness and firing temperatures, making it ideal for beam lead bonding. The absence of glass makes available more gold for easier silicon gold eutectic formation. Compatibility was also shown to be improved.
The effect of prolonged elevated temperature exposure on thick-film resistors. K. R. BUBE.
Proceedings I S H M Microelectronics Symposium, OctoberNovember (1972), p. 2-A-6-1. A commercially available resistor system, Cermalloy,* is examined after prolonged exposure to the 875°C processing temperature. The observed increase in sheet resistance is examined as a function of resistor, conductor and substrate composition. Material compositions, microscopic, analytical data and sheet resistance changes are correlated and evaluated. Mechanisms for the sheet resistance increase are discussed and include inter-phase diffusion, devitrification, volatilization, sintering and reduction-oxidation reactions. It is concluded that sintering of the conductive phases is the chief cause for the observed sheet resistance increase and is dependent upon substrate density and termination composition.
Thick-film resistor production monitoring by m e a n s of a graphical computer printout. J. B. McCLOGHRIE. Proceedings I S H M Microelectronics Symposium, October-November (1972), p. 2-B-2-1. The conventional statistical description of the reproducibility of a production batch of thick-film resistors, as a mean value and standard deviation, or the display of the distribution as a histogram, often conceals such features as long-term trends during production and discontinuities in these trends due to unsuspected changes in process conditions. A computer program has been prepared which prints out an analogue display of the resistance values on each substrate in turn, thus providing a graphic illustration of the way in which the histogram builds up as the batch progresses. This can be used as a method of process monitoring and also as a research tool, which often shows the true significance of the statistical results
WORLD
ABSTRACTS
ON MICROELECTRONICS
sium, October-November (1972), p. 2-B-4-1. Monolithic IC manufacturers have employed automatic test systems (ATS) successfully for the past several years. Hybrid circuit manufacturers have been employing such systems relatively recently and may not have attained the same level of success. This paper has made an attempt to investigate that point. T h e paper presents some helpful suggestions for justifying ATS, their selection criteria and examples of their capabilities. The author also presents the results of a nation-wide survey of the use made of automatic test systems by various hybrid circuit manufacturers. A yield analysis m o d e l for hybrid microelectronie circuits. A. LEw. Proceedings I S H M Microelectronics Symposium, October-November (1972), p. 2-B-3-1. Correct yield analysis and projection are paramount to profitable manufacture in today's competitive climate. Yields must be carefully projected in order to generate accurate cost estimates at the proposal stage, and yield attrition must be controlled during the production phase in order to maintain profit levels and schedules. This paper delineates the process flow for various hybrid microelectronic fabrication techniques and develops a mathematical model for the calculation of yield accumulation. T h e model defines the impact of accumulating yield attrition on sequential process steps in terms of labor and material costs. The expressions used in the mathematical model are designed to make it readily adaptable to computerized calculations and to the analysis of more complicated sequential processes.
Computer applications to the hybrid m i c r o e l e c tronic circuit design. V. M. SHUKLA. Proceedings
1SHM Microelectronics Symposium, October-November (1972), p. 2-B-5-1. Computer application in the field of the hybrid cirouit design is described in this paper. The computer has application in each of the following four prime areas of hybrid design: (1) package selection; (2) film resistor design; (3) substrate layout design; and (4) artwork generation. An algorithm used in developing a computer program for package selection for hybrid circuits is described. Resistor design computer program is also discussed. The computerized system flow diagram is presented to illustrate how the computer aids in substrate layout design and generation. Finally, the overall flow chart is presented to discuss computeraided design, and to give complete explanation of the computer as an aid and its application in the hybrid circuit design.
Characterization of a thick-film resistor conduction m e c h a n i s m . A. B. USOWSKI and A. J. VAN ZEELAND. Proceedings I S H M Microelectronics Symposium, October-November (1972), p. 2-A-2-1. A model of the conduction mechanism in a transition metal thickfilm resistor was generated using an experimentally determined relationship between voltage coefficient of resistance and sheet resistivity at low voltage stresses. The equation derived suggests a resistor conduction mechanism of an ohmic d e m e n t in parallel with a field
AND
RELIABILITY
dependent dement. The resistance vs. voltage characteristics over a range of temperatures were also investigated to isolate temperature dependency in the model. A n i n n o v a t i o n i n gold paste. B. R. SMITH and R. L. DIETZ. Proceedings I S H M Microelectronics Symposium, October-November (1972), p. 2-A-5-1. A new glassfree gold paste composition is described and compared with the conventional (fritted) gold paste in bonding mechanisms and properties. Alumina adhesion strengths were measured from two to five times greater than that of conventional golds. Adhesion to beryllia was comparable to Moly M n at about 9000 psi. The absence of a glass thermal barrier at the ceramic interface results in a 20-30 per cent increase in thermal conductivity in a D I P alumina package. The significantly lower thermal resistance of the chip bond allows better utilization of the thermal properties of BeO as well as more efficient use of heat sinking in higher power applications. The T C bondability was shown to be improved, more consistent, and less sensitive to gold thickness and firing temperatures, making it ideal for beam lead bonding. The absence of glass makes available more gold for easier silicon gold eutectic formation. Compatibility was also shown to be improved.
The effect of prolonged elevated temperature exposure on thick-film resistors. K. R. BUBE.
Proceedings I S H M Microelectronics Symposium, OctoberNovember (1972), p. 2-A-6-1. A commercially available resistor system, Cermalloy,* is examined after prolonged exposure to the 875°C processing temperature. The observed increase in sheet resistance is examined as a function of resistor, conductor and substrate composition. Material compositions, microscopic, analytical data and sheet resistance changes are correlated and evaluated. Mechanisms for the sheet resistance increase are discussed and include inter-phase diffusion, devitrification, volatilization, sintering and reduction-oxidation reactions. It is concluded that sintering of the conductive phases is the chief cause for the observed sheet resistance increase and is dependent upon substrate density and termination composition.
Thick-film resistor production monitoring by m e a n s of a graphical computer printout. J. B. McCLOGHRIE. Proceedings I S H M Microelectronics Symposium, October-November (1972), p. 2-B-2-1. The conventional statistical description of the reproducibility of a production batch of thick-film resistors, as a mean value and standard deviation, or the display of the distribution as a histogram, often conceals such features as long-term trends during production and discontinuities in these trends due to unsuspected changes in process conditions. A computer program has been prepared which prints out an analogue display of the resistance values on each substrate in turn, thus providing a graphic illustration of the way in which the histogram builds up as the batch progresses. This can be used as a method of process monitoring and also as a research tool, which often shows the true significance of the statistical results