IEC Technical Report 60068-3-12

IEC TR 60068-3-12:2022(E) which is a Technical Report, describes the creation of temperature-time profiles (in specific envelope profiles) for reflow soldering of electronic assemblies, considering tolerances resulting from the accuracy of the measuring equipment, preparation method and specifications of the manufacturers of components, circuit boards, solder paste, etc.).
This edition includes the following significant technical changes with respect to the previous edition:
a) Extended purpose
Guidance is added on how to create a reflow profile considering the tolerances resulting from the accuracy of the measuring equipment, preparation method and specifications of the component manufacturers (components, PCB, solder paste, etc.).

b) Distinction from existing standards
The envelope profile given in this document does not represent a temperature-time profile for the qualification of materials but defines the reflow process limits for the soldering of electronic assemblies.
The schematic temperature-time-limit curves of the envelope profile are derived from generally valid findings (literature data). Additionally, tolerance considerations are given for all envelope points of the envelope profile.
In contrast to IEC TR 60068-3-12:2014, the creation of the envelope profile is not primarily linked to a concrete example.
c) Subclause 8.2 presents an approach for establishing a possible temperature profile for a lead-free reflow soldering process using SnAgCu solder paste that is taken from IEC TR 60068-3-12:2014.

d) Synergies with existing standards
Limit values and tolerances from standards and guidelines for the qualification of materials are included in this document and are listed as examples in the references.