What is BS EN 61191-4 - Requirements for terminal soldered assemblies about?  
BS EN 61191 is an international standard that discusses printed board assemblies. The main objective of the BS EN 61191 series is to provide manufacturers of printed board assemblies with best industry guidance on ensuring their products play a positive role in the functioning of electronic applications.
BS EN 61191-4 is the fourth part of the IEC 61191 series that prescribes requirements for terminal soldered assemblies. The requirements pertain to those assemblies that are entirely terminal/wire interconnecting structures or to the terminal/wire portions of those assemblies that include other related technologies (i.e. surface mounting, through-hole mounting, chip mounting).
Who is BS EN 61191-4 - Requirements for terminal soldered assemblies for? 
BS EN 61191-4 on requirements for terminal soldered assemblies is useful for: 
- Manufacturers of electronic equipment and components
- Manufacturers of printed board circuits and semiconductors
- Manufacturers of automotive parts
- Manufacturers of surface mounting devices
- Electronic engineers
- Product design engineers
Why should you use BS EN 61191-4 - Requirements for terminal soldered assemblies?  
A PCB works at the heart of every electronic device. However, for its optimal functioning, adopting best industry practices on attaching electrical components to the circuit board via soldering, is vital.
BS EN 61191-4 provides you with best industry requirement and practices for designing and assembling these printed boards. The requirements provided can also aid in better selection of insulation materials, that can withstand higher external stresses.
Terminal and part mounting requirements are also covered in BS EN 61191-4.
BS EN 61191-4 provides guidance on terminal installation and acceptance requirements.
If you are a manufacturer, complying with these requirements can help minimize risks of defects for terminal attachment and soldering defects. These defects could be related to charred wiring insulation or components, nicked or broken strands in excess of limits provided in BS EN 61191-4, and inadequate stress relief on leaded components and wires.
Thus, BS EN 61191-4 can be your guide on ensuring terminal soldered assemblies impart adequate level of bonding between layers. If you are a manufacturer, this can ultimately help ensure that the electrical functions are fully implemented, thus contributing to the overall quality, reliability and performance of the end-use application.
What’s changed since the last update?
BS EN 61191-4:2017 supersedes BS EN 61191‑4:1999, which is withdrawn. BS EN 61191-4:2017 includes the following technical changes with respect to BS EN 61191‑4:1999:
- The requirements have been updated to be compliant with the acceptance criteria in IPC-A-610F
