How does pH affect PCB cleaning?
Understanding pH levels
pH measures solution acidity or alkalinity. Cleaning chemistries range:
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acidic (pH < 7) for mineral scale and oxide removal;
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neutral (pH ~7) for gentle cleaning;
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alkaline (pH > 7) for saponification and hydrolysis of organic residues.
Most aqueous PCB cleaners are mildly alkaline to attack flux residues without damaging base metals.
Impact on cleaning efficacy
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Alkaline chemistries accelerate removal of rosin and organic flux components by saponification.
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Acidic chemistries help remove metal oxides, but risk dissolving sensitive metals and solder.
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pH also affects surfactant performance, corrosion inhibitors, and chelant activity.
ZESTRON recommends pH control within +/- 0.5 units for consistent performance and provides analytical services to monitor pH trends in production.