Poh: I believe what you are seeing is a reaction between the 245 flux residue and the solvent/carrier in the 955. The 245 core solder leaves behind a rosin/resin encapsulated residue on the board. The 955 flux contains a large amount of 2-propanol, I believe about 90%. This alcohol in the 955 will react with and disturb the 245 resinous flux shell. It will start to break it down but not completely solvate it. It results in a powdery white granular appearance that can be a collection site for contaminants and moisture. To clean the existing assemblies you can use a solvent cleaner and a brush. Typically ones designed for rosin and/or resin removal seem to work best. Some of the Bioact and Flux-off spray cleaners will work but all require mechanical help. Apply cleaner, brush and re-apply cleaner until flux residue is gone. To prevent it on future product you may want to use Kester RF741 auxiliary flux in place of the 955. Regards Michael Barmuta Staff Engineer Fluke Corp. Everett WA 425-446-6076 -----Original Message----- From: Poh Kong Hui [mailto:[log in to unmask]] Sent: Saturday, June 22, 2002 8:17 AM To: [log in to unmask] Subject: [TN] : White residue using Kester flux & wire Hi All, I have problem using the Kester 955 flux with R245 wire. We manually used these material to solder a row of connectors. In term of soldering quality, it is alright, except it turned white after 3 to 4 days. Is there anyone has experience such issue, and what can I do to prevent this from happening. Our customer is not very happy with the white stuffs, but there is not solution to the issue. Thanks. Poh ---------------------------------------------------------------------------- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------- ----- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------