I would also theorize that the mechanical strength of the parylene strengthens the solder joint. We saw increased resistance to low cycle fatigue on boards coated with this versus over other coatings or a baseline with nothing under the parts. It wasn't as good as underfill but was a slight improvement over nothing at all. Sorry guys, data not available. From: Douglas Pauls <[log in to unmask]> To: [log in to unmask] Date: 07/14/2010 02:44 PM Subject: Re: [TN] Underfill as a Remedy for Electro Migration? Sent by: TechNet <[log in to unmask]> Ken, Yes, the parts were as underfilled as I could get them. There was some voiding and open areas as the liquid coating shrank when the solvents escaped. The forces come from CTE mismatches that accumulate through the bulk of the material. I would not expect Parylene or other chemical vapor deposition coatings to have the same issues. Lesser CTE values and far less bulk. Doug Pauls Ken Harp <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 07/14/2010 12:07 PM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to Ken Harp <[log in to unmask]> To [log in to unmask] cc Subject Re: [TN] Underfill as a Remedy for Electro Migration? I have a tangential question for Doug regarding the BGA thermal cycling performed with conformal coating as underfill...it looks like the BGAs in question were completely underfilled with conformal coating (from the board up to the underside of the BGA package). Is this correct? Any experience(s) with the effects on solder joint fatigue/reliability when using thin film vapor condensate parylene coating in leiu of acrylic or Loctite products for BGA underfill? --------------------------------------------------- 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 ----------------------------------------------------- ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- 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 ----------------------------------------------------- ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- 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 -----------------------------------------------------