Hi Suzanne -
        I have had white residue problems similar to yours but under 
     different circumstances. We found white residue on the pads/solder 
     fillets after a saponified water wash. The soldering process was RMA 
     wave flux, no nitrogen, wave solder process. The white residue was NOT 
     saponifier (we were using an Alpha product, basically a soap). We 
     found (after an enormously long investigation) that the white residue 
     was due to high water wash temperatures (greater than 150 F). We were 
     getting some type of lead - wash temperature reaction, most likely 
     related to the saponifier chemistry also, due to a run away heater. 
     The problem was corrected by replacing the heaters and improving the 
     temperature controls. You are using a different cleaning system than 
     we did but you may want to check out the temperature issues.
     
     Dave Hillman
     Rockwell Collins
     [log in to unmask]
     


______________________________ Reply Separator _________________________________
Subject: White residue/lead oxide
Author:  [log in to unmask] at ccmgw1
Date:    5/7/96 12:16 PM


We have a white residue problem at another division that has been analyzed 
using FTIR and SEM EDAX that has shown it to be lead oxide.  The white residue 
is located on pads/solder fillets.  The following process is used:
     
a.  Yokota flow solder (preheat 220F topside, 495F solder pot (less than 3 
seconds), conveyor speed 3.5 ft/min) 
b.  Kester 197 foam fluxer (rma)
c.  Cleaner is Bioact EC7R in a Ney spray under immersion or ECD batch 
diswasher.  Temperature of EC7R 90-95F, Rinse waters 130F.
     
The white residue is observed after cleaning and is insoluble in alcohol 
water/EC7R.
     
Any input on things to look for would be greatly appreciated.  We are running 
tests at other divisions with different flux chemistries/board design/process 
parameters.
     
[log in to unmask]