A concentration method that works on fresh cleaner may need additional review once the bath contains process residues. Before dosing a working wash tank, confirm that the measurement distinguishes the cleaner concentration from the effects of accumulated contamination.
Identify the method’s demonstrated range
ZESTRON’s concentration-control discussion explains that flux residues can affect refractive-index-based concentration readings. The practical implication is to use the chemistry supplier’s approved method for the actual loaded bath, rather than assuming a fresh-solution chart remains sufficient.
Record cleaner formulation, intended concentration range and measurement procedure. Keep manual and automated methods separately identified when both are used. Agreement should be established under representative working conditions, not only immediately after tank makeup.
Describe the sampled bath state
| Field | Record |
|---|---|
| Bath identity | Tank and chemistry designation |
| Process loading | Relevant use since makeup or maintenance |
| Temperature | Sampling and measurement condition |
| Mixing state | Approved representative sampling condition |
| Recent additions | Water, concentrate or other authorized changes |
Take samples from the defined location and sequence. A stagnant pocket or a sample collected during an incompletely mixed addition may not represent the operating bath. Record the actual event instead of assigning every sample the nominal tank condition.
Resolve disagreement before dosing
If the inline sensor and manual result diverge, follow the approved comparison procedure. Check method applicability, reference materials and sample handling. Do not average incompatible readings and use the result as a dosing instruction.
For example, a gradual change correlated with residue loading may require a review of analytical selectivity. A sudden change after replacing a sensor or reagent may instead begin with a measurement-system check.
Keep a traceable aliquot where appropriate for supplier investigation. Mark the sample’s physical source clearly; unused concentrate or freshly mixed cleaner cannot substitute for the working bath in that comparison.
Record whether a measurement was taken before or after filtration, treatment or tank circulation resumed. Those events can change the sampled condition. When comparing samples, use the same defined route so a location difference is not mistaken for a concentration trend.
Keep concentration separate from bath fitness
A concentration within range does not prove that every aspect of the bath remains acceptable. Follow the supplier’s additional maintenance and contamination criteria, and verify actual cleaning performance on the relevant assemblies.
Document the adjustment and the subsequent verification. If a bath is replaced, preserve the reason so the next cycle can distinguish consumption, contamination and measurement issues.
The rinse-conductivity guide addresses the next process stage, while localized residue analysis evaluates the board rather than the wash tank.
Move from reading to a build-ready project
Use the fabrication and assembly checklists to prepare drawings, production files and test requirements.
Open the DFM checklist