IEC 60539-2:2010 pdf – Directly heated negative temperature coefficient thermistors – Part 2: Sectional specification – Surface mount negative temperature coefficient thermistors.
4.9 Thermal shock
See 4.21 of IEC 60539-1 with the following details:
— the thermistors shall be mounted according to 4.1:
— the zero-power resistance shall be measured according to 4.4.1.
The test shall be carried out according to IEC 60068-2-14. Test Nc with the following details:
a) the lower temperature TA shall be the lower Category temperature:
b) the higher temperature T8 shall be the upper category temperature:
c) the exposure time,, shall be 30 mm;
d) the number of cydes shall be 5:
e) the medium of the test bath shall be oil.
The thermistors shall be visually examined and the zero-power resistance shall be measured. Under normal lighting and approximately lOx magnification, there shall be no signs of damage such as cracks.
The zero-power resistance change shall not exceed ±5 %.
4.10 ClImatic sequence
See 4.22 of IEC 60539-1 with the f 01 lowing details:
— the thermistors shall be mounted according to 4.1;
— the tests and measurements shall be performed in the following order.
4.10.1 Initial measurements
The thermistors shall be dried using procedure I of 4.3.1 of IEC 60539-1.
The zero-power resistance shall be measured according to 4.4.1.
4.10.2 Dry heat
The thermistors shall be subjected to the test described In 4.24 of lEG 60539-1 for a duration of 16 h.
4.10.3 Damp heat (cyclic), first cycle
The thermistors of categories —1—156, —1—142, —1—121, —1—110 and —1—/04 shall be subjected to test Db of IEC 60068-2-30 for one cycle of 24 h.
After recovery the thermistors shall be subjected immediately to the cold test.
4.10.4 Cold
The thermistors shall be subjected to the test described in 4.23 of IEC 60539-1 for a duration of 2 h.
4.10.5 Damp heat (cyclic), remaining cycles
The thermistors shall be subjected to Test Db of IEC 60068-2-30, for the number of cycles of 24 h shown in Table 5.
— after intermediate measurements, the thermistors shall be returned to the conditions of test, The interval between the removal from, and the return to. the conditions of test for any thermistor shall not exceed 12 h;
– after 1 000 h ± 48 h the thermistors shall be removed and allowed to recover under standard 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 lOi magnification, there shall be no signs of damage such as cracks, The zero power resistance change shall not exceed ±5 %.
4.12.2 Endurance at upper category temperature See 4.26.4 of lEG 60539-1 with the following details:
— the thermistors shall be mounted according to 4.1;
— the zero-power resistance shall be measured according to 4.4.1;
— 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 the requirements of that specified for Test Ba of lEG 60068-2-2:
— after 168 h and 500 h the thermistors shall be removed from the chamber and allowed to recover under standard atmospheric conditions of testing for not less than 1 h and not more 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 conditions of test. The interval between the removal from, and the return to. the conditions of test for any thermistor shall not exceed 12 h;
— after 1 000 h ± 48 h the thermistors shall be removed and allowed to recover under standard 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 lOx magnification, there shall be no signs of damage such as cracks. The zero-power resistance change shall not exceed ±5 %.
4.13 Shear (adhesion) test See 4.28 of IEC 60539-I.
4.14 Substrate bending test
See 4.29 of IEC 60539-1 with the following details:
— deflection D and the number of bends shall be specified in the detail specification:
— the zero-power resistance change shall not exceed ±5 %.
4.15 Component solvent resistance See 4.30 of IEC 60539-I with the following details:
— before and after the test, the zero-power resistance shall be measured.
— the thermistors shall be visually examined and the zero-power resistance shall be measured, Under normal lighting and approximately lOx magnification, there shall be no signs of damage such as cracks. The zero-power resistance change shall not exceed ±5 %.
4.16 Solvent resistance ot marking See 4,31 of IEC 60539-1.