Hi all,

My shop just bought a batch cleaner (dishwasher type); the manual says it is Aqueous Technologies, with an onboard cleanliness tester. This is a resistivity meter that measures the resistance of the rinse water, and I believe it has a range of 2k to 2000k ohm. This unit has both a closed-loop wash and  rinse, and we are using DI water. Does anyone have any experience with this type of cleaner with an "onboard cleanliness tester"?  Is this mostly for process control?  The manual is recommending a baseline cleanliness of 200-400 kOhm. I realize that this tester is not going to provide a level of cleanliness or contamination of each board processed, but I'm not sure what it is good for other than indicating the rinse water needs to be changed.

I was not involved in the selection of this system, but tasked with qualifying it.  My previous experience has been with no-clean processes, so cleaners are new to me!  I should add that currently we process a very small volume of PCBAs for space. All work is hand assembly and cleaning is by hand with Ensolv. The goal is to get away from Ensolv while still achieving clean boards. This shop has never done ionic contamination testing, ROSE, SIR, etc.  I believe some people were sold on the "onboard cleanliness tester" as a cure-all for aqueous cleaning validation, but I'm skeptical as to the benefits.  Any insight is appreciated.


Howard A. Watson


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