relying on software blindly is dangerous. Understanding the underlying math in the PDF allows a designer to audit a software-generated footprint and spot anomalies. If a wizard creates a footprint that violates the minimum annular ring or spacing rules defined in IPC-7351C, the PDF serves as the ultimate adjudicator.
Class 3 PCBs are designed and fabricated to meet stringent requirements of medical, aerospace, and military applications. Sierra Circuits ipc-7351c pdf
: Most land protrusion, best for easy soldering and rework. Level B (Median) : Nominal land protrusion for general use. relying on software blindly is dangerous
IPC-A-610 is the "Acceptability of Electronic Assemblies" standard, which outlines specific soldering and mounting criteria. Matric Group PCB Footprint Design Guidelines and IPC Standards Explained Class 3 PCBs are designed and fabricated to
Before 7351C (and its predecessor, IPC-SM-782), many designers used "nominal" footprints. This led to tombstoning, voiding, and fillet failures. The C revision codified the :