Definition of junction temperature (TJ)

1. in measuring the thermal resistance of semiconductor device packages, the temperature of the semiconductor junction in which the major part of the heat is generated. The measured junction temperature is indicative only of the temperature in the immediate vicinity of the element used to measure the temperature. Junction temperature is measured in degrees Celsius. [SEMI G38-87] Also see integrated circuit (The "J" part of the abbreviation is written with a subscript capital letter.)