Blistering

Blistering is a specific form of delamination in which the base material of the printed circuit board detaches locally from the copper layers and forms visible blisters or bulges. This phenomenon typically occurs during the soldering process when moisture that has penetrated the material suddenly evaporates and the resulting vapour pressure forces the layers apart. In contrast to flat delamination, blistering is usually localised, but is nevertheless a serious quality feature as it impairs the insulation capability and leads to mechanical stresses in the adjacent conductor tracks. Blistering is detected during quality control.