You have received such excellent advice that there is little to add 
except that you need to look at the process holistically from design to 
finished product, with full qualification procedures. Once qualified, 
you need to have statistical process control to ensure that nothing goes 
off the rails.

Expanding on what Mike said, mechanical removal of rinse water is 
actually a very important part of the cleaning process. Rinsing is a 
successive dilution of the dirty wash water; at the end, you may have a 
concentration of, say, 0.1% of the contaminants in the last rinse water, 
but they are still contaminants. Remove that water mechanically and you 
remove the contaminants with it. Let it evaporate, and your contaminants 
remain on your board, concentrated where surface tension takes them, 
ie., where you least want them, around the solder joints.

Brian

William D. Mengers wrote:
> Can anyone tell me what the latest and greatest "safe-to-the-hardware" PWA 
> cleaning methods and solvents there are these days.  One of my co-workers 
> has been tasked with buying a new cleaning system for PWA's.  Any 
> information will be appreciated.
> 
> Thank you,
> Bill
> 
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