Some of the big guns are away and have not been heard from.What do you think about this 0402 chip problem Moonman? Regards, Ramon > -----Original Message----- > From: Steve Gregory [SMTP:[log in to unmask]] > Sent: Monday, January 12, 2004 3:23 PM > To: [log in to unmask] > Subject: Re: [TN] reflowing 0402 SMT capacitors with underside terminations > > Hi Tom! > > There's a few articles out there that talk about "Phased Reflow Soldering". > Here's a link to one: > > http://www.reed-electronics.com/semiconductor/index.asp?layout=article& > articleid=CA274087&industryid=3026 > > Something I've done in the past that works really well in my opinion, is to > use a 2% > silver solder paste. Sn62/Pb36/Ag2...works in the same way that Phased Reflow > does. > The difference is pretty dramatic when it comes to eliminating tombstones! > > -Steve Gregory- > > > > Greetings All, > > > > I am having my first experience working with an assembly design that > > involves 0402 capacitors with underside solderable terminations (vice > > wrap-around end terminations)... The reflow process seems to cause the > > components to tilt and skew to highly unacceptable levels. Physically it > > looks as if the caps floated to the top of the molten solder volume (as if > > on pontoons) then slid down one way or the other. The vendor made a few > > recommendations including migration to a thinner (4 mil) stencil as well as > > some pad design and nitrogen tweaks and... Even after implementing these > > recommendations we are experiencing the same problems, just to a slightly > > lesser (although still unacceptable) degree... Does anyone out there have > > any additional thoughts on how to remedy this sort of issue? > > > > We do build another part [successfully] with a similar style component, but > > it is a 1206 form factor and is perhaps massive enough to keep from floating > > up the way the 0402 caps do... > > > > Your collective wisdom is greatly appreciated! > > > > Best Regards, > > > > Tom Ochenas > > Process Engineering > > Maxtek Components Corporation > > 2905 SW Hocken Avenue > > Beaverton, OR 97005 > > [log in to unmask] > > desk: 503-627-3078 > > fax: 503-627-4651 > > > > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 1.8e > 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 847-509-9700 ext.5315 > ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 847-509-9700 ext.5315 -----------------------------------------------------