David, I would be interested in seeing a copy of the paper you refer to in your reply. Would you be kind enough to e-mail a copy to me? Peter Barton Senior Process Engineer ACW Technology Limited Dinas Isaf West Tonypandy Mid Glamorgan CF40 1XX E-mail [log in to unmask] ===== Original Message from [log in to unmask] (TechNet E-Mail Forum.) at 21/06/02 03:10 >You have landed in a very nasty area. You are correct to be concerned >about contamination issues. >Even if the residues from the flux do not create migration/leakage >current problems they may >collect other airborne contaminates that can cause problems. > >Process, shipping, and storage control are critical to the reliability >of the circuitry. > >If you wish I have a paper I presented in May of 2001 titled >"Avionics Systems, Reliability, and Harsh Environments" >that I could e-mail you. The information in the paper will >give you a good idea of what type of airborne contamination >issues you may have to deal with. > >David A. Douthit >Manager >LoCan LLC > >Bogert wrote: > >> 6/20/2002 Folks is anyone manufacturing military PWAs using no-clean >> flux and not cleaning the PWAs prior to shipment? If so, what is your >> reliability experience with this process? We are considering a >> military application (Class 2) where mixed technology (SMT and PTH) >> PWAs will be soldered using no-clean flux and then not conformal >> coated (assuming the uncoated PWAs can pass our temperature/humidity >> qualification testing). Although the no-clean flux we will use should >> be benign (we are having SIR testing performed to confirm this and >> Omegameter testing), I am concerned that contamination may be >> introduced by other shop processes such as mechanical assembly, >> testing, etc., even if one uses gloves or fingere cots during >> handling. One could argue that after shipment, since the PWAs are not >> conformal coated, you can introduce contamination in the field and >> therefore, why not not clean prior to shipment. We may be performing >> board testing (boundry scan, bed-of-nails, etc) on PWAs that have been >> soldered using no-clean flux. I understand that certain noclean flux >> can impede this testing, and also, may cause problems in event we need >> to conformal coat the PWAs. Any comments on this subject will be >> appreciated. ----------------------------------------------------------------------- Peter Barton Senior Process Engineer ACW Technology Ltd Dinas Isaf West Tonypandy Mid Glamorgan. CF40 1XX Wales Tel: 01443 425200 Fax: 01443 436882 International Tel : +44 1443 425200 Fax : +44 1443 436882 E-mail: [log in to unmask] Website/URL: www.acw.co.uk --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------