Temperature Limits, Ratings, and Natural Cooling Procedures for Avionic Equipment and Parts

The results of adequate cooling of electronic parts are gains in part life and reliability. An engineering compromise between ideal electronic part temperature and the thermal point of diminishing return must be evaluated not only with respect to desired life, but also in terms of the electronic circuit and cooling efficiencies. This paper outlines the flow of heat within, through, and from heat producing electronic parts in terms of internal thermal limitations, part surface and environmental ratings, and cooling indices. Natural heat flow design data pertinent to conduction cooling of heat sources, tube shields, the placement and mounting of parts, and "sink connectors" are presented.