Overview
IEC 61191-4:2017 - "Printed board assemblies - Part 4: Sectional specification - Requirements for terminal soldered assemblies" - is an IEC standard that prescribes workmanship and acceptance requirements specifically for terminal soldered assemblies. It applies to assemblies that are entirely terminal/wire interconnecting structures and to the terminal/wire portions of assemblies that also include other technologies (surface mounting, through‑hole mounting, chip mounting). Edition 2.0 (2017) was revised to align its acceptance criteria with IPC‑A‑610F.
Key topics and technical requirements
The standard complements the generic IEC 61191‑1 requirements and focuses on terminal and wire interconnection specifics. Major topics include:
- Normative references: IEC 61191‑1:2013 (generic soldered assembly requirements) and IEC 60194 (terms/definitions).
- Wire and cable preparation:
- Insulation stripping, avoiding nicks or strand breakage.
- Tinning requirements for stranded wire to ensure solder wetting and penetration.
- Table of allowable nicked/broken strand limits by assembly level (A, B, C) and strand count.
- Terminal installation (mechanical and electrical):
- Acceptable terminal configurations (e.g., rolled or flared flange) and seating criteria.
- Prohibitions on perforations, cracks, or discontinuities that trap flux or contaminants.
- Mounting practices:
- Wire and lead wrap‑around, side/top/bottom route connections, continuous runs, and service loops.
- Insulation clearance, orientation of wire wrap, and stress relief methods.
- Special cases (pierced/perforated terminals, cup/hollow cylindrical terminals).
- Acceptance and inspection:
- Acceptance requirements for terminal soldering and plated through‑holes.
- Control and corrective actions and guidance for rework of unsatisfactory soldered connections.
- Workmanship: Explicit alignment with IPC‑A‑610 workmanship classes and acceptance criteria.
Practical applications and who uses this standard
IEC 61191‑4:2017 is used by:
- PCB assemblers and contract manufacturers implementing reliable terminal soldering processes.
- Quality engineers and inspectors performing acceptance testing and production audits.
- Design and process engineers specifying terminal mounting, clearance, and wire routing to meet manufacturability and serviceability requirements.
- Procurement and compliance teams verifying supplier conformity to international acceptance criteria (including IPC‑A‑610F alignment).
Benefits include improved joint reliability, reduced rework, consistent inspection criteria, and clearer design-to-manufacture requirements for terminal/wire interconnections.
Related standards
- IEC 61191‑1:2013 - Generic specification for soldered electrical/electronic assemblies (mandatory part of IEC 61191‑4).
- IPC‑A‑610F - Industry acceptance standard whose criteria are adopted for workmanship and acceptance in this edition.
- IEC 60194 - Terms and definitions used in PCB design and assembly.
Keywords: IEC 61191-4:2017, terminal soldered assemblies, printed board assemblies, wire preparation, tinning, insulation clearance, IPC‑A‑610F, acceptance criteria, soldering workmanship.