Analytical Spectrometry Replenishment Rhythms for High Volume Substrate Electroplating Lines
Analytical spectrometry rhythms must match chemical depletion kinetics to prevent microvia voids and control costs on high-volume substrate plating lines.
Chemical Drag-Out
Meaning
Physical carryover occurs when process solution adheres to the surface of parts and racks as they are lifted out of a treatment tank and transferred to the next step of the production line. This phenomenon, known as chemical drag-out, represents a major source of chemical loss and a significant contributor to rinse water contamination. The volume of liquid carried over is determined by the viscosity of the solution, the geometry of the parts, and the withdrawal speed.
Loss Mechanism
Viscous solutions and complex part geometries with deep recesses retain larger volumes of the bath chemistry during retrieval. This carried liquid is subsequently washed away in the rinse tanks, where it cannot be recovered easily and must be treated as waste. The loss of expensive additives and metal salts directly increases the operating costs of the production line.
Mitigation Strategy
Extended drain times over the process tank and the use of air knives can greatly reduce the volume of liquid carried over. Automated hoist programs can be adjusted to include a pause above the bath to allow excess chemistry to drip back into the tank. These mechanical adjustments preserve chemistry and reduce waste.
Rinse Impact
Dilute contaminants in the rinse water require continuous treatment to meet discharge standards. High carryover rates overload the wastewater treatment system. This impact makes drainage a critical factor.