SMD components require precisely sized soldering pads during assembly. Many of the footprints created by PCB designers are still based on data sheets and IPC-7351's standard pad and land size calculations as below.
PTH Hole and PAD Size Calculator Refers to IPC-2222
According to IPC-2222 standard, there are three design producibility levels of features, tolerances, measurements, assembly, testing of completion or verification of the manufacturing process that reflect progressive increases in sophisticaltion of tooling, materials or processing and, therefore progressive increases in fabrication cost. These levels are:
Level A : General Design Producibility - Preferred
Level B : Moderate design Producibility - Standard
Level C : High Design Producibility - Reduced.
Below is the calculator for the PTH hole and PAD design.
