Overview
IEC 61188-5-5:2007 is an international standard for PCB designers and electronics assemblers that defines land pattern geometries for components with gull‑wing leads on four sides (quad packages such as PQFP/CQFP). The document describes appropriate land sizes, shapes and tolerances to ensure adequate solder fillet formation and to allow reliable inspection, testing and rework of surface‑mount solder joints. It is intended to be read in conjunction with IEC 61188-5-1 (generic attachment requirements).
Key topics and requirements
- Component family coverage: Guidance covers four‑sided gull‑wing packages (PQFP, CQFP and variants including PLQFP, PTQFP), with lead pitches typically in the 1.0 mm to 0.30 mm range.
- Land pattern design: Recommended land geometries and identification system for robustness, based on a mathematical model that balances land protrusions and courtyard excesses.
- Three‑level dimensioning: Land patterns are provided at three robustness levels (maximum, median, minimum) to accommodate manufacturing tolerances and different design priorities.
- Solder joint fillet: Guidance on fillet geometry to ensure sufficient wetting and mechanical attachment for various solder alloys (including lead‑free and tin‑lead), emphasizing process compatibility.
- Process considerations: Primarily targeted at reflow soldering and stencil/paste application; notes on wave‑soldering modifications (orientation and solder thieves) where applicable.
- Inspection, testing and rework: Land pattern layouts are specified to permit visual/X‑ray inspection, electrical testing and practical rework processes.
- Reference model: Land pattern dimensions are derived from the generic requirements in IEC 61188-5-1, ensuring consistency across the IEC 61188 series.
Applications
- PCB footprint creation for quad gull‑wing ICs in CAD libraries.
- Design verification to achieve reliable solder fillets and manufacturability for surface‑mount assemblies.
- DFM/DFT checks during PCB layout and assembly process planning.
- Establishing inspection criteria and rework strategies for high‑density quad packages.
- Use by electronics OEMs, contract manufacturers (CMs), and test engineers to align PCB design with assembly process capabilities.
Who should use this standard
- PCB designers and CAD library engineers
- Process engineers (assembly and soldering)
- Quality, inspection and test engineers
- Contract manufacturers and EMS providers
- Product reliability and rework specialists
Related standards
- IEC 61188-5-1 - Printed boards and printed board assemblies - Design and use - Part 5-1: Attachment (land/joint) considerations - Generic requirements
- Other parts of the IEC 61188 series for broader PCB design and use guidance
Keywords: IEC 61188-5-5, land pattern, gull-wing leads, PQFP, surface mount, solder fillet, PCB design, printed boards, reflow soldering, land/joint considerations.
Open preview (PDF)Printed boards and printed board assemblies - Design and use - Part 5-5: Attachment (land/joint) considerations - Components with gull-wing leads on four sides
