If you are using a saponifier, measurements based on PH will be unreliable.
For process monitoring of the sort you are looking for consider monitoring
the conductivity of the rinse water.
You would need to set up an initial investigatory procedure to establish your
own parameters. Basically you would need to plot rinse water conductivity
against actual board quality. For that you need something like an Ionograph
and for final assembly quality SIR to correlate to Ionograph to.....
Your cleaning machine and flux vendors will have been asked this type of
question many times and should be able to answer your questions readily.

Mike Fenner

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################