Hi Ron -
     
     We have run into the same "opportunity"! As part of our transition 
     from RMA type fluxes to low residue materials there was a point when 
     both materials were on the factory floor (and there are still a few 
     holdouts that still have an RMA flux pen stashed away for use!). As 
     part of our compatibility testing we looked at what would happen if 
     the RMA and low residue materials ended up mixing and found no 
     problems. We have phased in low residue flux pens that perform the 
     same function as the old RMA pens and it was not too tough to get 
     acceptance on the factory floor. The easy test is to run an SIR coupon 
     that has a RMA/low residue mix on it that has seen your process flow 
     (i.e. duplicate the factory situation) - that will give you some proof 
     that there are no compatibility issues
     
     After going through the RMA to low residue conversion I really have to 
     laugh at what we (well, military assemblers anyway) lived with for so 
     long. We could only use RMA type fluxes because the activators were 
     not aggressive enough to cause corrosion and the Rosin portion of the 
     flux would "trap" the activators that didn't decompose during 
     soldering. Yet, there was always a requirement to clean flux off of 
     the assemblies and leave no residue - talk about a strange logic 
     sequence! Low residue materials are more process sensitive but 
     definitely have advantages over RMA's in the assembly process. Good 
     luck with your transition.
     
     
     Dave Hillman
     Rockwell Collins
     [log in to unmask]
     


______________________________ Reply Separator _________________________________
Subject: subject: Flux Marking Pens & No-clean Process
Author:  [log in to unmask] at ccmgw1
Date:    2/11/97 9:17 AM


     Good Morning TechNet!
     
     I would like to submit a question to the forum members using 
     No-clean/Low-residue fluxes.  Are any of you using flux marking pens 
     to identify defects?  If so, how are you removing the flux from the 
     marking pen?  My delimena, I think, is, if I am in the process of 
     removing inline cleaners by moving to No-clean/Low-residue fluxes, 
     yet, I use a RMA type flux pen to mark a defect that will need to be 
     cleaned off, then it would seem I am defeating my purpose of 
     No-clean/Low-residue flux transition.
     
     Has anyone any experience on this?  Can you leave the marks on the 
     CCA?  If so do you have any data to show no electromigration/dendritic 
     growth/fungus growth or problems long term from Hallides ...etc...?
     
     I would appreciate some discussion since I know there is quite a bit 
     of valuable experience out there in cyberspace.
     
     Thanks in advance for your inputs.  
     
     Ron Hollandsworth
     [log in to unmask]
     IR&D Operations Task Leader
     ITT Aerospace/Communication Division
     
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