From:	NAME: WILLIAM G KENYON              
	FUNC: Chemicals/Electronics           
	TEL: 302-652-4272                     <KENYONWG AT A1 AT ESVAX>
To:	NAME: [log in to unmask] <"[log in to unmask]"@ESDS01@MRGATE@ESVAX>


Many of us would be interested to know how you made your ionic 
contamination measurements; what instrument, what test solution, 
what test time etc.
Northern Telecom had determined that the low ionic results often 
obtained with water washing of water soluble fluxes were in fact 
due to the slow "release rate" of such residues from the PWA 
surfaces.  They determined that 90+% of rosin flux residue was 
released into the 75/25 (v/v) test solution within 15 minutes, 
but that it took almost 120 minutes to achieve the same level of 
extraction of flux residues from water solubles.  Thus the PWA's 
soldered with water soluble flux "appeared" to be cleaner than 
the traditional rosin flux--- when a 15 minute test time was 
used.  You might wish to run a follow-up experiment to determine 
the release rate of your water soluble fluxes and pastes vs. 
ionic test time to check this point out and assure yourself that 
the low ionic readings are indicative of clean PWAs.
W. G. Kenyon