Definition
Delamination is the separation of the bonded layers inside a printed circuit board, either between copper and laminate or between the epoxy resin and the glass-fiber weave that reinforces it. It can appear as visible blisters or measling on the board surface, or remain hidden internally as a debonded resin-glass interface. Once layers separate, the mechanical integrity and the insulation properties of the board are compromised.
Causes
Delamination is typically driven by trapped moisture flashing to steam during a hot reflow or rework step (the so-called popcorn effect), by exceeding the laminate's glass transition temperature, or by repeated thermal cycling that stresses the resin-glass bond through expansion mismatch. Hand soldering with excessive heat on a single pad and aggressive rework are common shop-floor triggers.
Why it is dangerous
Beyond the obvious mechanical weakness, a debonded glass-resin interface opens a pathway for conductive anodic filament (CAF) growth: under voltage bias and moisture, copper can migrate along the separated glass bundle and form an internal short between conductors. This makes delamination both a structural and an electrical-reliability problem. Preventive practice includes baking moisture-sensitive boards before reflow, controlling soldering temperature and dwell time, and choosing high-Tg laminate for hot-running assemblies like hashboards.
For related internal-failure topics, see our entries on dendrite growth and reflow profiles.
In Simple Terms
Delamination is the separation of the bonded layers inside a printed circuit board, either between copper and laminate or between the epoxy resin and the…