HDBK-217 PREDICTION_TEMPERATURE

[felice]

Hello
I am sort of a novice in Reliability Analysis,and would like your help: We are doing reliability analysis on a tactical radio. Radio has many boards in a closed Aluminum chasis. The ambient temperature inside the box (ie radio) will be about 75°C. When we initialize the parameters for the analysis do we set the ambient temperature at 75°C or air ambient temperature outside the box (ie 25°C).
Many tks for your help.

Phil

 

[IRstuff]

Generally, the temperature of interest is the junction temperature, but you'd have to look at the software to see what they want. As a general rule, the ambient temperature is usually higher than 25ºC for the purposes of reliability analysis. On a large enough program, there's an operational scenarios document that will let you figure out the percentage of time at the different temperatures that the system is supposed to see. You would then have a bunch of different conditions to add together.

TTFN

FAQ731-376