Manufacturing tolerances are the amount of variation that is allowed in a measurement
or other characteristic of an object.
Ref: Collins English Dictionary
Tolerances are everywhere, they are applied to everything that is manufactured whether it is a simple screw, a mobile phone or a spacecraft, they are all affected by tolerances and PCB’s are no different.
Even our domestic electricity has a tolerance, for example in Europe it is approx. +/- 6%.
When you design a new product, you do so with a specific set of dimensions in mind, these are known as the nominal dimensions.
However, these must have a tolerance, no matter how small (or large) they must exist to allow for cost effective manufacture.
We should all know that the smaller (tighter) the tolerance the higher the cost of manufacture will be.
For industrial PCB production there are international standards for these tolerances. We produce all our boards according to the “IPC-A-600 Acceptability of Printed Boards” version F (http://www.ipc.org/TOC/IPC-A-600F.pdf) Class II (Industrial products).
Using the Eurocircuits Insight Technology platform together with Eurocircuits TV we have created a series of informative guides that help explain these manufacturing tolerances.
Our first guide in this series is:
Finished Hole Size Tolerances
The finished hole size on a PCB is affected by the following factors:
Type of Hole – Plated, Non-Plated or Via.
Nominal Hole Size vs available Drill Bit Sizes.
Drill Bit Size Tolerance.
Drill Bit Wear during use.
Hole Cleaning (Desmear).
The Plating Process and Copper Balance.
The Final Surface Finish of the PCB.
To read more on how and why these factors influence the finished hole size on a PCB simply click on the button below.