DIN EN IEC 60539-1:2024-09

This part of IEC 60539 is applicable to directly heated negative temperature coefficient thermistors, typically made from transition metal oxide materials with semiconducting properties. It establishes standard terms, inspection procedures and methods of test for use in sectional and detail specifications of electronic components for quality assessment or any other purpose. A thermistor is a thermally sensitive semiconductor resistor with the basic function that a change in the temperature of the component body results in a significant change in its electrical resistance value. A temperature-dependent resistor with a negative temperature coefficient (NTC resistor) is a thermistor whose resistance value decreases as the temperature rises. The term "NTC resistor" is generally used. A directly heated negative temperature coefficient thermistor is a thermistor whose resistance change is caused by a change in physical conditions. Physical conditions include the current flowing through the thermistor, the ambient temperature, the humidity, the wind speed, gas, and so on. The thermistor shall be clearly marked with the following information, in the order specified, as far as space permits: the nominal value of the no-load resistance, the name and/or logo of the manufacturer, the date of manufacture, the limit deviation for the nominal value of the no-load resistance, and the detail specification and type. The packaging of NTC resistors shall be clearly marked with all of the above information. Any additional markings shall be affixed in such a way that no ambiguity can arise. The clause on general provisions for measurement and test procedures states that the sectional specification and/or the form for detail specification shall contain tables with information on which tests are to be performed, which measurements are to be taken before and after each test or subgroup of tests, and in what order they shall be performed. The steps of each individual test shall be carried out in the specified order. The measurement conditions for initial and final measurements shall be the same. If national specifications within a quality assessment system include procedures other than those specified in the sectional specification and/or the detail specification form, then these shall be described in full. Further clauses deal with electrical tests and measurements, mechanical tests and measurements, environmental and climatic tests, and tests relating to component assembly. Normative Annex A contains rules for the preparation of detail specifications for capacitors and NTC resistors for electronic devices for use in quality assessment systems, informative Annex B contains typical examples of fastenings for the measurement of directly heated thermistors, and informative Annex C contains the quality assessment procedure. There are no restrictions on the scope of application of the document. Its application increases investment security for manufacturers and users, provides testing laboratories and manufacturers with defined information for testing, and increases product compatibility between manufacturers.