Water spots form when minerals and residues precipitate during drying. They can create insulation issues and degrade solderability.

Impact of water spots on PCB performance

Spots can raise leakage currents, create dendritic growth sites, and lead to cosmetic rejects. In high-voltage and microelectronics, even minor spots can have outsized effects.

Prevention techniques

• use DI or ultra-pure water for final rinse to remove minerals

• control drying to avoid slow evaporation which concentrates residues

• consider isopropyl alcohol or volatile rinses for hydrophilic surfaces

• inspect with UV or optical methods to detect faint spots

ZESTRON recommends final rinse resistivity monitoring and drying practices to eliminate spot formation.