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 latest guide:

Layer to Layer Registration Tolerances

The accuracy of layer to layer registration is one of the most important parts of the PCB production process.

Get it wrong and the holes may breakout of the copper pads.

Our goal is always to deliver your PCB’s with the layer to layer registration accuracy as close to perfect as possible.

However, there are many factors that influence this accuracy and we use our experience and expertise to compensate for them during production.

One of the latest and most important additions to our factories has been Direct Imaging (DI).

Using DI for the imaging of the copper layers and Soldermask has enabled us to improve our registration capabilities as it eliminates the need for Photo-tools.

Photo-tools are extremely sensitive to temperature and humidity and will distort with the smallest of change in either of these.

DI is digital printing and uses state-if-the-art CCD cameras to detect predefined targets (holes or fiducials).

These are then used to align the image to the panel.

For inner layers it even prints the targets directly on L3 using a UV Marker system whilst it prints L2,

This greatly improves the layer to layer registration accuracy for inner layer cores.

We produce all our boards according to the IPC-A-600 Acceptability of Printed Boards  (Industrial products).

To read more and see our video on how and why these factors influence the final track width & isolation gap on a PCB simply click on the button below.