Core Wash

Process Mechanism

High pressure spray nozzles deliver deionized water or specialized detergents to the board surfaces. A thorough core wash eliminates the chlorides and sulfates left behind by the etching chemistry. Without this removal, the residues react with moisture over time to form conductive anodic filaments.

The mechanical action of the rollers also assists in dislodging physical debris. The rinsing stage follows the chemical application to neutralize the surface pH and prevent the formation of localized corrosion cells during storage.

Assembly Impact

Poor adhesion of the prepreg to the inner layer often stems from inadequate surface preparation during the fabrication of the substrate. If the core wash fails to achieve the required level of cleanliness, the resulting board may pass electrical tests but fail during the thermal stress of lead free soldering. Cleanliness is measured through ionic contamination testing or surface energy analysis.