IEC 60068-2-67-2019 pdf download.Environmental testing — Part 2-67: Tests — Test Cy: Damp heat, steady state, accelerated test primarily intended for components
Essais d’environnement — Partie 2-67: Essais — Essai Cy: Essai continu de chaleur humide, essai accéléré applicable en premier lieu aux composants.
This IEC 60068-2-67 provides a standard test procedure for the purpose of evaluating, in an accelerated manner, the resistance of small electrotechnical products, primarily non hermetically sealed components, to the deteriorative effect of damp heat.
The test is not intended to evaluate external effects such as corrosion and deformation.
2 General description
In this test the specimen is subjected to very high levels of unsaturated damp heat for a relatively long period.
Electrical bias is usually applied.
The test provides a number of preferred durations at a relative humidity of 85 % and a temperature of 85 °C.
In the case of plastic encapsulated components degradation results from absorption of water- vapour by the plastic and penetration of moisture along terminals.
3 Description of test apparatus
3.1 The test chamber
The chamber shall be so constructed that:
a) it can produce the temperature and relative humidity given in table 1 for a minimum period of 2 000 h without interruption;
b) it is capable of providing controlled conditions of temperature and relative humidity during testing, and the ramp-up to and ramp-down from specified test conditions;
c) the temperature and humidity of the chamber can be monitored by means of sensing devices located in the working space and/or other areas giving the same results;
d) any water shall be continuously drained from the working space and not re-used; e) condensed water is not allowed to fall on the specimen:
f) the materials used in the construction shall not cause any significant corrosion of the specimen, or degradation of the quality of the humidifying water (see clause B.1).
The temperature tolerance of ±2 C is intended to take account of absolute errors in the measurement, fluctuations of the chamber temperature at any point and variations between any two points within the working space.
Care shall be exercised in the choice of mounting structure and mounting fixture materials to minimize the effects of contamination and to minimize degradation due to corrosion and other mechanisms (see clause B.1).
7.3 If required by the relevant specification the specimen shall have a bias voltage applied during testing. Guidance on the application of bias is given in clause B.2.
The bias voltage (or bias voltage cycle) shall be applied to the specimen when the temperature and the relative humidity have reached the stable state and continue until the specimen Is under recovery conditions.
7.4 Test cycle
7.4.1 The temperature and relative humidity of the chamber shall be raised to their appropriate values. During this period the temperature and the relative humidity shall not exceed the specified value. Condensed water is not allowed on the specimen at any time during the test cycle. Stabilization of temperature and humidity shall take place within 3 Ii.
7.4.2 The temperature and relative humidity shall be maintained within the prescribed limits for a duration as specified in the relevant specification. The duration shall commence as soon as the conditions have stabilized.
7.4.3 At the end of the specified duration, the chamber temperature and relative humidity shall be restored to standard atmospheric conditions for measurement and tests in not less than 1 h and not more than 4 h.
During this period, the temperature and the relative humidity shall not exceed the specified value. The bias shall be maintained during this period.
7.4.4 On completion of the cooling period the specimen shall be subjected to the recovery procedure.
8 Intermediate measurements
The relevant specification may require electrical and/or mechanical checks during testing.
If it is required to make intermediate measurements, the relevant specification shall define the measurements and period(s) during testing after which they shall be carried out. The measurements shall not cause any change to the test conditions.IEC 60068-2-67-2019 pdf download.Environmental testing