IEC 60539-2-2019 pdf free.Directly heated negative temperature coefficient thermistors Part 2: Sectional specification- Surface mount negative temperature coefficient thermistors.
The zero-power resistance shall be measured in accordance with 7.4.1.
The thermistors shall be subjected to Test Cab of IEC 60068-2-78 using the severitycorresponding to the climatic category of the thermistor as given in the detail specification.
At the end of the test,the thermistors shall be removed from the chamber and shall then besubjected to recovery in accordance with 7.3.2.The thermistors shall be visually examined, and the zero-power resistance shall be measured.Under normal lighting and approximately 10x magnification, there shall be no signs of damagesuch as cracks.The zero-power resistance change shall not exceed +5 %.
See lEC 60539-1:2016,5.25.4, with the following details:- the thermistors shall be mounted in accordance with 7.1;
– the zero-power resistance shall be measured in accordance with 7.4.1;
– the thermistors shall be placed in a test chamber and subjected to the temperature
T3± 2°℃ for 42 days (1 000 h) and at dissipation Pmax;
after 168 h and 500 h, the thermistors shall be removed from the chamber and allowed torecover under standard atmospheric conditions of testing for not less than 1 h and notmore than 2 h;
the zero-power resistance shall be measured, and its change shall not exceed ±5 %;
after intermediate measurements, the thermistors shall be returned to the test conditions.The interval between the removal from，and the return to,the test conditions for anythermistor shall not exceed 12 h;
after 1 000 h ± 48 h, the thermistors shall be removed and allowed to recover understandard atmospheric conditions for a period of 1 h to 2 h;
See lEC 60539-1:2016,5.25,with the following details:
the thermistors shall be mounted in accordance with 7.1;
the zero-power resistance shall be measured in accordance with 7.4.1;
the thermistors shall be placed in a test chamber and subjected to the upper category
temperature ±2 °C and zero dissipation for 1 000 h. The chamber shall meet therequirements of that specified for Test Ba of lEC 60068-2-2;
after 168 h and 500 h, the thermistors shall be removed from the chamber and allowed torecover under standard atmospheric conditions of testing for not less than 1 h and notmore than 2 h;
the zero-power resistance shall be measured, and its change shall not exceed ±5 %;
after intermediate measurements, the thermistors shall be returned to the test conditions.The interval between the removal from，and the return to, the test conditions for anythermistor shall not exceed 12 h;
after 1 000 h ± 48 h,the thermistors shall be removed and allowed to recover understandard atmospheric conditions for a period of 1 h to 2 h;
the thermistors shall be visually examined,and the zero-power resistance shall be measured.Under normal lighting and approximately 10x magnification, there shall be no signs of damagesuch as cracks.The zero-power resistance change shall not exceed +5 %.IEC 60539-2 pdf download.