Bob Willis – Defect of the Month video guide

Welcome to our latest Defect of the Month – Solved, this month we illustrate PCB delamination, which can be very subtle or very obvious. Delamination is caused by expansion of moisture in the PCB laminate during soldering or rework but may not be the root cause. Often eliminating moisture prevents the energy build-up of water vapour that forces different layers apart, but this is not the complete story. Poor bonding during the manufacturing of the multilayer board or some form of contamination results in poor adhesion on inner layers, the ability for moisture to accumulate at these surfaces resulting in inner layer separation

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The first image  shows solder mask cracking around a through via.

The PCB has expanded then contracted during reflow and cooling. This resulted in lifting and cracking of the solder mask, plus intermittent electrical connection. 

The second image on the shows the inner layer surface of the board after separation. The through vias are separated and there is no visible adhesion on this layer

This is just one of the Defect of the Month videos previously featured by IPC, SMTA, SMART Group and Circuits Assembly magazine helping to provide better understanding of process issues and help support training of younger engineers. We have recently celebrated being a 100, that is the number of videos produced not Bob’s age Bob

Sponsor our videos and photographic defect guides

Here is your opportunity to sponsor our regular Defect of the Month videos on materials, soldering, assembly, cleaning and PCB design. Produced by Bob Willis over the years there are many topics which have been covered and are unique to the industry for further information on sponsoring Defect of the Month videos for either 6 or 12 months, contact

Here is a link to an example video

In addition, we also have our popular Photographic Process Defect Guides for engineers to download free after registering. Our first guide featured is the Solder Paste Print Inspection & Defect Guide

Our next two guides will feature: 

Low Temperature Solder Joint Inspection & Defect Guide

Robotic Soldering Guide, Inspection & Defect Guide

0201 & 01005 Chip Component Reflow & Defect Guide