IEC 60539-2 pdf download – Directly heated negative temperature coefficient thermistors – Part 2: Sectional specification – Surface mount negative temperature coefficient thermistors
4.7.2 Recovery
The flux residues shall be removed with a suitable solvent.4.7.3Final inspection, measurements and requirementsSee the detail specification with the following details:
– the surface mount thermistors shall be visually examined under normal lighting and
approximately 10x magnification and there shall be no signs of damage;
both the end face and the contact areas shall be covered with a smooth and bright soldercoating with no more than a small amount of scattered imperfections such as pinholes orun-wetted or de-wetted areas.These imperfections shall not be concentrated in one area.
48Rapid change of temperature
See 4.16 of IEC 60539-1.
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 lEC 60068-2-14,Test Na with the followingconditions:
a) the lower temperature TA shall be the lower category temperature;b) the higher temperature TB shall be the upper category temperature;c) the number of cycles shall be 5;
d) the medium of the test chamber is air.
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 %.
4.9Thermal shock
See 4.21 of lEC 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 lEC 60068-2-14,Test Nc with the following details:a) the lower temperature TA shall be the lower category temperature;
b) the higher temperature Te shall be the upper category temperature;c) the exposure time r i shall be 30 min;
d) the number of cycles 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 10x magnification, there shall be no signs of damagesuch as cracks.
The zero-power resistance change shall not exceed +5 %.
4.10Climatic sequence
See 4.22 of IEC 60539-1 with the following details:- the thermistors shall be mounted according to 4.1;
– the tests and measurements shall be performed in the following order.
4.10.1Initial measurements
The thermistors shall be dried using procedure l of 4.3.1 of IEC 60539-1.
The zero-power resistance shall be measured according to 4.4.1.
4.10.2Dry heat
The thermistors shall be subjected to the test described in 4.24 of lEC 60539-1 for a durationof 16 h.
4.10.3Damp heat (cyclic),first cycle
The thermistors of categories —–/56,—1-/42,–/21,–/10 and —l—/04 shall be subjected totest Db of lEC 60068-2-30 for one cycle of 24 h.
After recovery the thermistors shall be subjected immediately to the cold test.4.10.4cold
The thermistors shall be subjected to the test described in 4.23 of IEC 60539-1 for a durationof 2 h.
4.10.5 Damp heat (cyclic), remaining cycles
The thermistors shall be subjected to Test Db of lEC 60068-2-30 , for the number of cycles of24 h shown in Table 5.
After the test, the thermistors shall be subjected to recovery according to 4.3.2 ofIEC60539-1.
4.10.6 Final measurements
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 15 %
4.11 Damp heat, steady state
See 4.25 of lEC 60539-1.
The thermistors shall be mounted according to 4.1 of lEC 60539-1.
The zero-power resistance shall be measured according to 4.4.1.
The thermistors shall be subjected to Test Cab of lEC 60068-2-78 using the severity
corresponding 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 according to 4.3.2 of IEC 60539-1.
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 %.
4.12Endurance
4.12.1Endurance at 0s and P max.
See 4.26.3 of lEC 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 temperature
03±2 °C for 42 days (1 0o0 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 15 %;
IEC 60539-2 pdf download – Directly heated negative temperature coefficient thermistors – Part 2: Sectional specification – Surface mount negative temperature coefficient thermistors
