Power MOSFET Thermal Instability Operation Characterization Support

Metal-oxide semiconductor field-effect transistors (MOSFETs) are used extensively in flight hardware and ground support equipment. In the quest for faster switching times and lower "on resistance," the MOSFETs designed from 1998 to the present have achieved most of their intended goals. In the quest for lower on resistance and higher switching speeds, the designs now being produced allow the charge-carrier dominated region (once small and outside of the area of concern) to become important and inside the safe operating area (SOA). The charge-carrier dominated region allows more current to flow as the temperature increases. The higher temperatures produce more current resulting in the beginning of thermal runaway. Thermal runaway is a problem affecting a wide range of modern MOSFETs from more than one manufacturer. This report contains information on MOSFET failures, their causes and test results and information dissemination

More About Arc-Welding Process for Making Carbon Nanotubes

High-quality batches of carbon nanotubes are produced at relatively low cost in a modified atmospheric-pressure electric-arc welding process that does not include the use of metal catalysts. What would normally be a welding rod and a weldment are replaced by an amorphous carbon anode rod and a wider, hollow graphite cathode rod. Both electrodes are water-cooled. The cathode is immersed in ice water to about 0.5 cm from the surface. The system is shielded from air by flowing helium during arcing. As the anode is consumed during arcing at 20 to 25 A, it is lowered to maintain it at an approximately constant distance above the cathode. The process causes carbon nanotubes to form on the lowest 5 cm of the anode. The arcing process is continued until the anode has been lowered to a specified height. The nanotube-containing material is then harvested. The additional information contained in the instant report consists mostly of illustrations of carbon nanotubes and a schematic diagram of the arc-welding setup, as modified for the production of carbon nanotubes

Risk assessment of metal vapor arcing

A method for assessing metal vapor arcing risk for a component is provided. The method comprises acquiring a current variable value associated with an operation of the component; comparing the current variable value with a threshold value for the variable; evaluating compared variable data to determine the metal vapor arcing risk in the component; and generating a risk assessment status for the component

Tin Whiskers: A History of Documented Electrical System Failures

This viewgraph presentation reviews the history of tin and other metal whiskers, and the damage they have caused equipment. There are pictures of whiskers on various pieces of electronic equipment, and microscopic views of whiskers. There is also a chart with information on the documented failures associated with metal whiskers. There are also examples of on-orbit failures believed to be caused by whiskers

Metal Vapor Arcing Risk Assessment Tool

The Tin Whisker Metal Vapor Arcing Risk Assessment Tool has been designed to evaluate the risk of metal vapor arcing and to help facilitate a decision toward a researched risk disposition. Users can evaluate a system without having to open up the hardware. This process allows for investigating components at risk rather than spending time and money analyzing every component. The tool points to a risk level and provides direction for appropriate action and documentation