@pindac,
Recognizing your issue with local very hard tap-water, your process looks great - try the distilled white vinegar before the Dehyphon final clean and that should improve your results.
I was misunderstanding your term "Ultrasound Solution"; I now realize you are discussing use of an ultrasonic tank (UT) for the final rinse. In this case, since you are doing a pre-clean and final clean, but with only a spray for rinse (I understand your tap-water issue) use of a ultrasonic tank for final rinse may improve the process.
If you proceed down this path, for final rinse using UT, 1st try using only DIW and see how that works. If you are not satisfied then add 2.5% IPA and see if that improves the results. As the final option add 0.005% Dephyon to the UT 2.5% IPA solution. UT results will be very dependent of the orientation of the transducers (side firing vs bottom firing); kHz frequency, tank capacity (Liters) and ultrasonic power. Lower kHz UT (~40kHz) need a lot of power to get good cleaning with just DIW.
Good Luck,
Neil
Recognizing your issue with local very hard tap-water, your process looks great - try the distilled white vinegar before the Dehyphon final clean and that should improve your results.
I was misunderstanding your term "Ultrasound Solution"; I now realize you are discussing use of an ultrasonic tank (UT) for the final rinse. In this case, since you are doing a pre-clean and final clean, but with only a spray for rinse (I understand your tap-water issue) use of a ultrasonic tank for final rinse may improve the process.
If you proceed down this path, for final rinse using UT, 1st try using only DIW and see how that works. If you are not satisfied then add 2.5% IPA and see if that improves the results. As the final option add 0.005% Dephyon to the UT 2.5% IPA solution. UT results will be very dependent of the orientation of the transducers (side firing vs bottom firing); kHz frequency, tank capacity (Liters) and ultrasonic power. Lower kHz UT (~40kHz) need a lot of power to get good cleaning with just DIW.
Good Luck,
Neil

