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The reliability of microwave radio-relay systems
ABSTRACTS ON MICROELECTRONICS AND RELIABILITY
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pass these may have latent failure mechanisms that come into play later. Here is where the user's task begins. He has recourse to two basis methods of weeding out latent failures. One way is to produce an actual failure from the latent mechanism by accelerated testing-burn-in, temperature cyelln~, and thermal shock, for example. The other method is to pick out failure-prone ICs before fabrication is completed. This second method is something new for IC buyers. It is effective because many failures are caused by manufacturing defects easily visible through a microscope. Defective units can therefore be identified by visual inspection of the ICs during the manufacturing process. IC manufacturers have done this for years, but visual inspection has not been performed to the customer's specification at low COSt. Boost reliability in your op-amp circuit. Build in redtmdnr~ey and get automntlc compmmation for i a t z r n ~ f a i l u r u . Part I of a two-part series. W. H. HuBs, Electron. Des. 14, July 4 (1968), p. 62. A self-correcting redundant amplifier will provide the extreme reliability you need. Consistln~ of three or more interconnected op amps, it has inherent redundancy that allows satisfactory operation even after one or more of the op amps fails. The range and accuracy of the failure compensation increases as the number of op amps in the circuit is increased. Dodge transducer failures with a RAMP. This highly reliable op mnp autovnat;cally corrects for the failure o f one or more of its redundant inputs. Second in a two-part series. W. H. H u m , Electron. Des. 15, July 18 (1968), p. 70. A multiple-input Redundant Amplifier (RAMP) automatically corrects for transducer failures--and for failures within itself. The cost of this reliability is a few extra components. You will need op amps for the RAMP circuit and extra transducers to provide the redundant inputs. Use of the RAMP circuit in your control system can end that ultimate reliance on a failure-prone transducer. The circuit is similar to the one discussed in Part I of this article but offers tolerance to failures in its redundant inputs as well as to internal failures. Dynamic IC testing m a d e easy. G. C. PADWICK,Electronics, September 30 (1968), p. 74. Static tests of I Ca are fairly simple and straightforward: steady-state voltages and currents are applied to certain terminals of the IC, and at the same time the resulting voltages and currents at the other terminals are measured. For digital ICs, static tests ensure that steady-state fan-out, noise immunity and power dissipation meet the specifications. Dynamic tests on the other hand measure the time-dependent parameters--propagation and transition times in a gate and set-up and release times in a flip-flop, for example. The important dynamic parameters of digital ICs are described, and are related to system functions. Although the examples deal specifically with T T L circuits, most of them are equally applicable to DTL, RTL and CML. The gate and the flip-flop are considered separately. Repairability o f printed wiring boards containing microelectronic devices. J. R. MATZnqOZa, Solid St. Technol., September (1968), p. 39. When a microelectronic device does fall, much valuable information such as vendor process problems and design misapplications can be gained by.studying failure modes and mechanisms. Therefore it is important that we have procedures for remowng these devices quickly and without further mechanical or electrical damage to either the device, adjacent devices, the printed wiring board, or multilayer board On which they are mounted. The purpose of this article is to discuss repair procedures applicable to the various microelectronic package styles. P r o g r a m m i n u and graphics support for infrared thermal plotters. A. D. LZWT, Mater. Eva/., September (1968), p. 180. Programming and graphics support is essential if one hopes to raise the status of laboratory thermal plotters from a curiosity to a significant, useful tool. Computer programs have been written to aid the development of the instrument by testing proposed techniques for data collection. It will be shown how computer programming was used in the investigation of the "one-~.an calibration" hypothesis, which if acceptable to the user, would substantially reduce the amount of time required to obtain me2n~ngful data. Once a system has been established, computer programming can yield a feasible method for data display and interpretation. Computer programs are used to convert "raw data" into the more physically meaningful temperature vs. {x, y) position from an initially established reference point in a plane. To obtain maximum insight into temperature distribution and heat flow, still another program is used to display these data in the form of isothermal contours. The benefits of this system, E
63
pass these may have latent failure mechanisms that come into play later. Here is where the user's task begins. He has recourse to two basis methods of weeding out latent failures. One way is to produce an actual failure from the latent mechanism by accelerated testing-burn-in, temperature cyelln~, and thermal shock, for example. The other method is to pick out failure-prone ICs before fabrication is completed. This second method is something new for IC buyers. It is effective because many failures are caused by manufacturing defects easily visible through a microscope. Defective units can therefore be identified by visual inspection of the ICs during the manufacturing process. IC manufacturers have done this for years, but visual inspection has not been performed to the customer's specification at low COSt. Boost reliability in your op-amp circuit. Build in redtmdnr~ey and get automntlc compmmation for i a t z r n ~ f a i l u r u . Part I of a two-part series. W. H. HuBs, Electron. Des. 14, July 4 (1968), p. 62. A self-correcting redundant amplifier will provide the extreme reliability you need. Consistln~ of three or more interconnected op amps, it has inherent redundancy that allows satisfactory operation even after one or more of the op amps fails. The range and accuracy of the failure compensation increases as the number of op amps in the circuit is increased. Dodge transducer failures with a RAMP. This highly reliable op mnp autovnat;cally corrects for the failure o f one or more of its redundant inputs. Second in a two-part series. W. H. H u m , Electron. Des. 15, July 18 (1968), p. 70. A multiple-input Redundant Amplifier (RAMP) automatically corrects for transducer failures--and for failures within itself. The cost of this reliability is a few extra components. You will need op amps for the RAMP circuit and extra transducers to provide the redundant inputs. Use of the RAMP circuit in your control system can end that ultimate reliance on a failure-prone transducer. The circuit is similar to the one discussed in Part I of this article but offers tolerance to failures in its redundant inputs as well as to internal failures. Dynamic IC testing m a d e easy. G. C. PADWICK,Electronics, September 30 (1968), p. 74. Static tests of I Ca are fairly simple and straightforward: steady-state voltages and currents are applied to certain terminals of the IC, and at the same time the resulting voltages and currents at the other terminals are measured. For digital ICs, static tests ensure that steady-state fan-out, noise immunity and power dissipation meet the specifications. Dynamic tests on the other hand measure the time-dependent parameters--propagation and transition times in a gate and set-up and release times in a flip-flop, for example. The important dynamic parameters of digital ICs are described, and are related to system functions. Although the examples deal specifically with T T L circuits, most of them are equally applicable to DTL, RTL and CML. The gate and the flip-flop are considered separately. Repairability o f printed wiring boards containing microelectronic devices. J. R. MATZnqOZa, Solid St. Technol., September (1968), p. 39. When a microelectronic device does fall, much valuable information such as vendor process problems and design misapplications can be gained by.studying failure modes and mechanisms. Therefore it is important that we have procedures for remowng these devices quickly and without further mechanical or electrical damage to either the device, adjacent devices, the printed wiring board, or multilayer board On which they are mounted. The purpose of this article is to discuss repair procedures applicable to the various microelectronic package styles. P r o g r a m m i n u and graphics support for infrared thermal plotters. A. D. LZWT, Mater. Eva/., September (1968), p. 180. Programming and graphics support is essential if one hopes to raise the status of laboratory thermal plotters from a curiosity to a significant, useful tool. Computer programs have been written to aid the development of the instrument by testing proposed techniques for data collection. It will be shown how computer programming was used in the investigation of the "one-~.an calibration" hypothesis, which if acceptable to the user, would substantially reduce the amount of time required to obtain me2n~ngful data. Once a system has been established, computer programming can yield a feasible method for data display and interpretation. Computer programs are used to convert "raw data" into the more physically meaningful temperature vs. {x, y) position from an initially established reference point in a plane. To obtain maximum insight into temperature distribution and heat flow, still another program is used to display these data in the form of isothermal contours. The benefits of this system, E