Definition
Blister is a localised swelling of laminate caused by separation between layers or between laminate and copper or solder mask. It is often triggered by heat and trapped moisture.
How It Works
During reflow or rework, absorbed moisture expands into vapour. If trapped, it forces layers apart, forming a blister. Poor storage, contamination or weak lamination processes increase the risk. Inspectors detect blisters as raised or domed areas under oblique light.
Practical Example
After seeing mask bubbles on a BGA site, an assembly team introduces pre‑baking of panels at 110°C to remove absorbed moisture. This prevents recurrence in subsequent builds.
Context & Relevance
Blisters link material handling with reflow and rework conditions, making moisture control and lamination quality essential to PCB reliability.
At Rework, we deliver hands-on training and IPC certification that helps teams understand and manage Blister. Our on-site and virtual courses are designed to improve skills, prevent defects and support reliable electronics assembly. Learn more.
