An optimal cleaning result in the electronics cleaning depends to a large extent also on the optimal working ability of the used detergent. If too many impurities (eg colophony entry) have been taken up, if cleaning temperatures of 50 °C upwards are applied (here the cleaner may lose larger proportions of liquid due to evaporation) or if too much concentrate has been added, the detergent may lose its stability and therefore significantly efficiency.
Therefore, a cyclic examination of the cleaning mixture is necessary to measure the current concentration and (if necessary) by post-dosing / adjusting the cleaner to ensure its effectiveness.
Two common methods are generally used for this purpose:
Cleaner concentration monitoring by ultrasonic measurement
Cleaner concentration monitoring by refraction measurement (measurement scale percent Brix / %Bx)
Applying the concentration / density measurement by ultrasonic waves, the substance-dependent sound propagation time is evaluated for density determination. On this basis, the associated concentration is calculated from each measured sound propagation time value.
Applying the refraction measurement, light waves are sent into the fluid. Depending on the density, these are broken differently. The detection of these refractions makes it possible to determine the concentration of a mixture.
A more detailed report about detergent monitoring you can read and download here.