Manufacturing tolerances are the amount of variation that is allowed in a measurement or other characteristic of an object.
Ref: Collins English Dictionary
We continue with our series on Understanding Tolerances on a PCB with our 5th guide:
Finished PCB Thickness Tolerances
As with all manufacturing processes the Finished PCB Thickness is influenced by various factors and thus there is a tolerance applied to the final thickness.
The process of manufacturing a PCB starts with the Base Materials (e.g. FR4) and these are available in various thicknesses.
Base material thicknesses have a tolerance as defined by the manufacture, for example for FR4 this is ±10%.
Added to this are the various other tolerances accumulated throughout the manufacturing process and this is where the Final PCB Thickness Tolerance is derived from.