Improving the Drill Chart

The Drill Chart is an important table on any fabrication drawing. It provides a legend for the many drill sizes, locations, and attributes desired in a PCB, helping bridge the gap from fabrication drawing requirements to the design data files. While always present in the design, there is one critical characteristic of a drill that is seldom addressed in a Drill Chart.

Annular Ring – Consider adding a column to the Drill Chart that lists the smallest Pad size for each drill size in the design. When adding the smallest pad size, please consider the minimum Annular Ring requirements as defined in IPC 2221 for the Class level desired. This will help communicate to Fabricators without even looking into the data files whether the design supports the minimum Annular Ring required for the build and can be identified as early as the Quote stage, avoiding the order being put On Hold and impacting schedule.