I wonder how often this problem occurs but nobody realizes it. For example, I am looking back at a shorting issue with power converters manufactured with no-clean flux. The terminal pins used to solder the converter to the motherboard were .010" apart, and were soldered onto the converter with a no-clean solder flux, but when the converter is soldered to the board the same terminals were soldered with water-soluble flux. There are literally hundreds of such examples out there. I do not know if a standard would preclude this from happening, but it could be mentioned in a DfR document. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis Sent: Friday, April 11, 2008 10:50 AM To: [log in to unmask] Subject: Re: [TN] Possible flux contamination issue 24 years ago (yes 24!), I gave a paper at InterNepcon, in Brighton, UK, entitled "Contamination on Components and Small Assemblies". I no longer have a copy, but I'm fairly sure I evoked the need to have all the components supplied clean to avoid just this kind of problem. Brian Steve Kelly wrote: > Good Morning, > > We are assembling a BGA connector onto a flex circuit. The BGA has > leaded balls and the BGA manufacturer uses a no-clean process to > attach the balls to the connector and does not clean afterwards. > > When we assemble the BGA connector to the flex we use water soluble > paste and then we clean. After damp heat cycling we have seen some > shorts. When we take off the connector we see flux residues on the > underside of the connector but not on the flex. So my question is - > what are the concerns about mixing no-clean and water soluble? Is the > failure likely due to inadequate cleaning or is there something else I should be concerned about. > I realize this is probably not the way it should be done but some days > you just do what the customer wants - good or bad. Thanks in advance. > Steve Kelly > > > > Steve Kelly > > (416) 750-8433 (work) > > (416) 750-0016 (fax) > > (416) 577-8433 (cell) > > > > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 15.0 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 15.0 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 -----------------------------------------------------