I'm about to embark on some designs where there'll be resistors in the ballpark of tens of megaohms, and I've been advised that with values that high, oil from one's skins and other typical contaminants can be enough to noticeably shunt the resistors and thereby introduce measurement errors. The test prototypes will also be hand-soldered, so there'll likely be some flux remaining on the boards as well.
Traditionally I've just cleaned boards with things like isopropyl alcohol and (ahem :-) ) Goo Gone, but for really good cleaning... does anyone have additional suggestions?
(I'm told that one of the biggest problems with oils that that they can change radically over time in terms of their impedance; you might calibrate a system one day, and find it woefully out of spec the next.)
Note that my "cleaning machinery" is limited to a couple of ultrasonic cleaners and dishwashers -- no fancy vapor phase degreasers around here. (Although if anyone knows of some relatively inexpensive machinery that's just the cat's meow, it is possible I could buy something.)
Thanks,
---Joel