摘要 :
This is the Final Engineering Report on Phase 2.2 work on the ultrasonic subsystem for the trend inspection station for printed circuit board solder joints. The report discusses activities during this contract period in six major ...
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This is the Final Engineering Report on Phase 2.2 work on the ultrasonic subsystem for the trend inspection station for printed circuit board solder joints. The report discusses activities during this contract period in six major areas. Probe assemblies have been refined by redesigning both receiver and transmitter to permit closer spacing of these probes for inspection of small joints. In addition, transmitter design has resulted in a new style probe. Based in part on the characteristics of ultrasonic spectra of the solder joint types of interest, and in part on the mental processes used in visual evaluation of joint spectra to make a judgment on joint quality, several algorithms have been investigated for computerizing the decision making process. A simple but effective algorithm has been devised for use with the latest probe set in inspecting good lap solder joints and those with heel cracks. A probe manipulator for the pilot model of the ultrasonic subsystem was designed and constructed during this contract period. It was used in some of the later experimentation in this period directed to defining performance capability.
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摘要 :
This is the Final Engineering Report on Phase 2.2 work on the ultrasonic subsystem for the trend inspection station for printed circuit board solder joints. The report discusses activities during this contract period in six major ...
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This is the Final Engineering Report on Phase 2.2 work on the ultrasonic subsystem for the trend inspection station for printed circuit board solder joints. The report discusses activities during this contract period in six major areas. Probe assemblies have been refined by redesigning both receiver and transmitter to permit closer spacing of these probes for inspection of small joints. In addition, transmitter design has resulted in a new style probe. Based in part on the characteristics of ultrasonic spectra of the solder joint types of interest, and in part on the mental processes used in visual evaluation of joint spectra to make a judgment on joint quality, several algorithms have been investigated for computerizing the decision making process. A simple but effective algorithm has been devised for use with the latest probe set in inspecting good lap solder joints and those with heel cracks. A probe manipulator for the pilot model of the ultrasonic subsystem was designed and constructed during this contract period. It was used in some of the later experimentation in this period directed to defining performance capability.
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An accelerated life test is described which was developed to predict the life of the 25 kW photovoltaic array installed near Mead, Nebraska. A quantitative model for accelerating testing using multiple environmental stresses was u...
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An accelerated life test is described which was developed to predict the life of the 25 kW photovoltaic array installed near Mead, Nebraska. A quantitative model for accelerating testing using multiple environmental stresses was used to develop the test design. The model accounts for the effects of thermal stress by a relation of the Arrhenius form. This relation was then corrected for the effects of nonthermal environmental stresses, such as relative humidity, atmospheric pollutants, and ultraviolet radiation. The correction factors for the nonthermal stresses included temperature-dependent exponents to account for the effects of interactions between thermal and nonthermal stresses on the rate of degradation of power output. The test conditions, measurements, and data analyses for the accelerated tests are presented. Constant-temperature, cyclic-temperature, and UV types of tests are specified, incorporating selected levels of relative humidity and chemical contamination and an imposed forward-bias current and static electric field.
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摘要 :
The fifth in a series of annual symposia on the Physics of Failure in Electronics convened at Battelle Memorial Institute in Columbus, Ohio, on November 15, 16, and 17, 1966. It was jointly sponsored by Rome Air Development Center...
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The fifth in a series of annual symposia on the Physics of Failure in Electronics convened at Battelle Memorial Institute in Columbus, Ohio, on November 15, 16, and 17, 1966. It was jointly sponsored by Rome Air Development Center and the Battelle-Columbus Laboratories. There were about 535 individuals in attendance, thirty of them from seven foreign countries. Centering almost exclusively on scientific inquiry into material processes and phenomena influencing the degradation and failure of solid state electronic devices and related structures, the Symposium technical program contained two invited papers, twenty-seven contributed papers, and seven late-news papers.
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