IPC-7351B refers to a 0.25 Courtyard Excess for Nominal Density Level. However, feedback from our customers indicate 0.20 Courtyard Excess works perfect. The Least Density Courtyard Excess is 0.10, Nominal 0.20 and Most is 0.40. There are 2 courtyard settings. One for the package body and one for the pads. The Package Body uses the Maximum package dimension.
Some Enterprise CAD tools turn the courtyard excess off to contour the courtyard to the maximum package dimensions. Then they use the courtyard for Placement Boundary or use the CAD tool rules for footprint to footprint spacing rules.
The manufacturing zone is intended for assembly shops who need more area around the footprint pattern. Your assembly shop needs to communicate this information.
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