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
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
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Low Temperature Solder Joint Inspection & Defect Guide
Robotic Soldering Guide, Inspection & Defect Guide
0201 & 01005 Chip Component Reflow & Defect Guide