Hi Kevin! I could give you the standard Doug Paul's response "it depends" but then I would owe him another Mt. Dew royalty! There are two prevailing groups of thought on flux selection for pretinning and you described both sides of the coin very well. IMHO I think that the water soluble solution is best choice with one very big qualifier- you must absolutely insure that the post pretinning cleaning process effectively neutralizes/removes any non-reacted flux material. There are some component types that you can not insure complete cleaning and therefore the rosin flux choice is more appropriate. I would not recommend using the "stock time-frame" as a screening method to see if corrosion is going to take place. Ion Chromatography is a good way to measure the effectivity of the post pretinning cleaning process. My vote is for the water soluble choice. Ok the count is water soluble: 2, rosin: 1. Next! Dave Hillman Rockwell Collins [log in to unmask] Kevin Glidden <[log in to unmask] COM> To Sent by: TechNet [log in to unmask] <[log in to unmask]> cc Subject 12/02/2005 03:36 [TN] Pre-tinning wire & components PM Please respond to [log in to unmask] om Hello all, Question on pre-tinning of components and wires. We are in a debate here. Is it desirable to pre-tin wires and components with a water soluble (high activity) or an RMA (low activity)? My position is that water soluble (high activity) is the preffered flux type over RMA to provide better pre-tin and also ease of cleaning. Others are arguing that there is significant risk in using the water soluble due to the corrosive residues, particularly if they are able to wick up the wire and under the insulation. They state rosin is to be used for pre-tinning to mitigate that risk. My issue with this method (aside from the lower activity level potentially yielding a lower quality pre-tin) is that our termination process can call for either rosin flux or water soluble flux, depending on the application or product, and I am concerned that any rosin residues from the pre-tin (more difficult to remove than water soluble) could negatively impact the termination solder joint. Another thing to consider is that we stock pre-cut and pre-tinned wires at point-of-use, so there could be a significant time-frame between pre-tinning and termination. Depending on your view, this could be time for the water soluble residue to work it's corrosive magic or for RMA residue to nicely harden. Thoughts? --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------