I will add one item to Mike's post. White residues are sometimes the interaction between the flux residue and moisture, either from an aqueous cleaning process or more often from the air itself. Heating the residue can drive off the moisture, making the residue clear again, but the white can return after 3-4 days at ambient humidity conditions. Faster if it is more humid. Doug Pauls Rockwell Collins Mike Fenner <[log in to unmask] To: [log in to unmask] om> cc: Sent by: TechNet Subject: Re: [TN] White residue <[log in to unmask]> 03/19/2004 03:10 AM Please respond to mfenner Very neat Bill thanks. May I suggest a refinement, or at least a flag, to test 3 the heat gun? If the residues are partially removed rosin or resin, which can also have a white or off white appearance, the heat gun will melt it to a translucent or clear appearance. Visually this would be similar to the powder disappearing. So the refinement would be to either know the generic flux type in use, or carry out an additional inspection, or pick at the area to see if the resides flake off. Regards Mike Fenner Indium Corporation --------------------------------------------------- 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 847-509-9700 ext.5315 -----------------------------------------------------