The New Proportional Land Dimensioning Concept
The difficulties that arise when processing printed circuit boards with connection surfaces that are too large have been the subject of many different working groups for many years.
The current standards for land dimensioning, such as the IPC-7351B or the IEC 61188-5 series, require a fundamental revision, as they do not meet the component types used today with their ever smaller package designs, terminals and pitches.
This volume 18 of the FED publication series "Library of Knowledge" presents a completely new approach to the calculation of SMD land dimensions on circuit boards and offers the user the following advantages:
- Easily scalable
- Only two terminal classes
- Easy adaptation also for future components
- Failure-reduced assembly process
- Risk minimization, e.g. bridging in paste printing
- Higher reliability of the solder joints
- Smaller land areas give more space for routing
The author Rainer Taube discusses the history of the standardization of SMD land pattern and the standards currently in force. This provides the reader with important background knowledge. In the course of his presentation, he explains the widely used IPC calculation model for land pattern. Based on these principles, he presents the New Proportional Land Dimensioning Concept he has developed. This is based on only two terminal classes, which in cover the entire SMD component spectrum. For the calculation of the lands a new IPC / FED reference calculator is available for download. A FED verification project was launched to ensure that the lands calculated according to the new proportional concept lead to acceptable solder joints that meet the requirements of J-STD-001 and IPC-A-610. A specially designed test board has land pattern of common SMD components according to IPC-7351B and the New Proportional Concept. Extensive photo material from the project documents the comparisons and highlights the final positive evaluation.