IEC 60539-2:20 19作为IEC 60539-2:20 19 RLV提供，其中包含国际标准及其红线版本，显示了与上一版本相比技术内容的所有变化。IEC 60539-2:20 19适用于表面贴装直接加热负温度系数热敏电阻，通常由具有半导体特性的过渡金属氧化物材料制成。这些热敏电阻具有金属化的连接垫或焊带，旨在直接安装在混合电路的衬底上或印刷电路板上。 与上一版相比，此版本包括以下重大技术变更: a)在可行范围内根据ISO/IEC指令第2部分:2016（第七版）对结构进行修订，并与IEC 60539-1:20 16保持一致； b)增加了表1中175℃、200℃、250℃、315℃、400℃的上限温度； c)增加了附录A中0402M的尺寸。

IEC 60539-2:2019 is available as IEC 60539-2:2019 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.

IEC 60539-2:2019 is applicable to surface mount directly heated negative temperature coefficient thermistors, typically made from transition metal oxide materials with semiconducting properties. These thermistors have metallized connecting pads or soldering strips and are intended to be mounted directly on to substrates for hybrid circuits or on to printed boards.
This edition includes the following significant technical changes with respect to the previous edition:
a) revision for the structure in accordance with ISO/IEC Directives, Part 2:2016 (seventh edition) to the extent practicable, and for harmonizing with IEC 60539-1:2016;
b) the upper category temperatures of 175 °C, 200 °C, 250 °C, 315 °C, 400 °C in Table 1 have been added;
c) the dimensions of 0402M in Annex A have been added.