IDENTIFICATION OF HIV T CELL EPITOPES

Not Available Hermetically sealed microcircuits, such as ceramics, have been used successfully in space, but there are potential cost, size, and weight advantages if plastic encapsulated microcircuits (PEMs) packaging is used for space application. Approximately 98% of all microcircuits manufactured in the world are housed in plastic packages. Ceramics will not be available, or very costly in the future because private industry is moving toward plastic encapsulation. Unless test procedures and acceptance/rejection criteria for space qualification of PEMs are developed, hermetically sealed microcircuits will still be required even though they are very expensive and/or very limited in availability. The problem with plastic packaging is that plastic materials are hygroscopic and contain brittle passivation layers, which are susceptible to stress cracking mainly from thermal cycling. Small amounts of moisture will lead to corrosion and, hence, early failure of the electronics. Because of moisture absorption and package cracking, commercial plastic encapsulated microcircuits manufactured today cannot pass at least five of the MIL STL 883 tests which, currently ceramic packages need to pass. At present there are no standards or requirements for PEMs for use in space stations. This proposed effort will develop test procedures and acceptance/rejection criteria for use of PEMs in space.