There are 2 types of slots on a PCB.
These Plated and Non-Plated both have the same Finished Slot Size tolerances regardless of size or type.
A slot is basically an elongated hole used for the fixation of components on a PCB and are usually defined in the drill layers.
The Finished Slot Size tolerances are based upon the following factors:Type of Slot – Plated, Non-Plated or Via.
- Nominal Slot Size vs available tool Sizes.
- Tool Bit Size Tolerance.
- Tool Bit Wear during use.
- Slot Cleaning (Desmear).
- The Plating Process and Copper Balance.
- The Final Surface Finish of the PCB.
Plated slots like plated holes are created larger than this required finished size, this is to allow for the manufacturing tolerances and downstream processes.
The amount by which the slot is enlarged is determined by the known accumulated manufacturing tolerances applicable to crating slots in a PCB.
There are 2 types of slots on a PCB, Plated and Non-Plated both have the same Finished Slot Size tolerance.