Definition of Tolerance for Manufacturing

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.

We always comply with the IPC-A-600 Acceptability of Printed Boards (Industrial products) standards for PCB thickness measurement and tolerance.

The thickness of a PCB must be measured on an area of laminate that is free of Soldermask, copper and legend.

To read more on how and why these factors influence the Finished PCB Thickness, simply click on the button below.