环境测试 第 3-12 部分：支持文档和指南 评估可能的无铅焊料回流温度曲线的方法

[中文适用范围]： IEC TR 60068-3-12 技术报告描述了在评估电子元器件组装的无铅回流焊温度曲线时，如何创建特定的温度 - 时间包络线轮廓（Envelope Profiles），同时考虑由测量设备精度、制备方法以及元器件、印刷电路板、焊膏等制造商规格所导致的公差。本文档中给出的包络线轮廓并不代表用于材料资格认证的温度 - 时间曲线，而是定义了电子元器件组装回流焊接的工艺窗口。 [外文原描述]： 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.