Not surprising he's concerned. I would be, too. 200 V/mm is a helluva gradient under normal conditions, let alone at 85/85. You will tear apart all the residual ions in FR-4 under those conditions. I would say the only possible way of ensuring electrical integrity is to make sure that everything is as clean as possible and then underfill/conformally coat with top quality resins. Brian Steve Kelly wrote: > Good Morning, > I need to ask some more questions on this thread. > One of the reasons our customer went to a water soluble paste was the high > voltage/damp heat test requirement on the finished assembly. > The test requirement is 1000 hours of damp heat test at 85C/85RH. The > voltage requirement is 250 volts. BGA pad spacing is .050. The customer was > concerned about passing this test. > Regards Steve Kelly > > Steve Kelly > PFC Flexible Circuits Limited > PH: (416) 750-8433 > Fax: (416) 750-0016 > Cell: (416) 577-8433 > > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Kelly > Sent: Monday, April 14, 2008 1:58 PM > To: [log in to unmask] > Subject: Re: [TN] Possible flux contamination issue > > Thanks everyone for the help. Regards Steve Kelly > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis > Sent: April-11-08 11:50 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 > ----------------------------------------------------- > > --------------------------------------------------- > 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 -----------------------------------------------------