Vlad - Joyce : 3 - 1 .....aaaahh....wife came with a drink...Famous Grouse+Martini+Dubonnet + ice......see yo 2morrou .. Inge ----- Original Message ----- From: "Vladimir Igoshev" <[log in to unmask]> To: <[log in to unmask]> Sent: Sunday, July 05, 2009 6:51 PM Subject: Re: [TN] Weird solder joints > Joyce, > > First of all there is no "free" Ag in SACs with less than 3.5 Ag and > secondly it is impossible to see ANY segregation at grain boundaries with > the techniques commonly used in the industry. Thirdly, I'm not aware of > any techniques which would allow segregation exclusively at triple > junction (and in essence it's just a dot in 2D !!!!). > > Sunday :-) > > Vladimir > SENTEC > 11 Canadian Road, Unit 7. > Scarborough, ON M1R 5G1 > Tel: (416) 899-1882 > Fax: (905) 882-8812 > www.sentec.ca > > > -----Original Message----- > From: Joyce Koo <[log in to unmask]> > > Date: Sun, 5 Jul 2009 12:12:46 > To: <[log in to unmask]> > Subject: Re: [TN] Weird solder joints > > > Too much brain on grain? SAC has ag sagrigation in grain boundary and > some ppc paticles of minor additives, assume add by vendor as grain growth > inhibitor, in triple junction. To assessing grain structure is possible > in some of the SAC I believe. Silly brain, go back to holiday mode. Left > side is shutting down. Zzzz. > -------------------------- > Sent using BlackBerry > > > ----- Original Message ----- > From: TechNet <[log in to unmask]> > To: [log in to unmask] <[log in to unmask]> > Sent: Sun Jul 05 11:47:18 2009 > Subject: Re: [TN] Weird solder joints > > Vladimir, Gaby, Inge, Mike - People!!! This is Sunday!! Are we trying to > start the work week a day earlier?? > > It is really close for Ingemar already! > > > Maybe this is the weekend troubleshooting crew! Kind of like the weekend > TV > anchor team... > > I can just imagine how Dewey's response to 'grains' might be related to > beverages. > > > Gaby - At least it appears that you have gotten a fair amount of > information > already this weekend - making your Monday a bit more efficient. > > I enjoyed the calm winds and 68-70°F temps to go flying this morning. > From > the micro to the macro. A pleasant change in perspective > > Enjoy the remainder of your Sunday > > Steve C > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Vladimir Igoshev > Sent: Sunday, July 05, 2009 10:20 AM > To: [log in to unmask] > Subject: Re: [TN] Weird solder joints > > Thank you inge, > > Even though I believe I know a few things, a person can not know > everything > :-). That is why I asked the question. > > Honestly, I'm still almost confused every time I hear someone referring to > the grain structure in solder joints. I know it's pain in the neck to > reveal the real grain structure in solders (and even more so in Pb-free > world, than in the eutectic one), meaning it's not a practical thing to > do. > > Therefore I always ask the same question: "what do you mean by "grain > structure" and almost always it turns out to be the phase (not grain) > structure, which makes much more sense to me. > > Honestly, I'm not even sure whether the grain structure (which would > mainly > their size inside the individual phase) plays a role in reliability of > solder joints. > > In fact, a few years ago we deliberately tried to grow Sn grains in one of > the SAC alloys and ended up with nothing - the original grain size (a few > microns) never changed. I thought it was very interesting. > > Regards, > > Vladimir > SENTEC > SENTEC > 11 Canadian Road, Unit 7. > Scarborough, ON M1R 5G1 > Tel: (416) 899-1882 > Fax: (905) 882-8812 > www.sentec.ca > > > -----Original Message----- > From: Inge <[log in to unmask]> > > Date: Sun, 5 Jul 2009 10:42:49 > To: <[log in to unmask]> > Subject: Re: [TN] Weird solder joints > > > Vlad, > > 1. the alloy members have solidified evenly all through the ball > 2. the distribution of phases are even > 3. the grains are fine > > you'd know it well, being a guru yaself > > Inge > > > ----- Original Message ----- > From: <[log in to unmask]> > To: "TechNet E-Mail Forum" <[log in to unmask]>; "Inge" > <[log in to unmask]> > Sent: Saturday, July 04, 2009 11:06 PM > Subject: Re: [TN] Weird solder joints > > >> Inge, >> >> Could you elaborate on what you mean by "good grain structure"? >> >> Thanks, >> >> Vladimir >> SENTEC >> SENTEC >> 11 Canadian Road, Unit 7. >> Scarborough, ON M1R 5G1 >> Tel: (416) 899-1882 >> Fax: (905) 882-8812 >> www.sentec.ca >> >> >> -----Original Message----- >> From: Inge <[log in to unmask]> >> >> Date: Sat, 4 Jul 2009 20:48:31 >> To: <[log in to unmask]> >> Subject: Re: [TN] Weird solder joints >> >> >> Gaby, >> solder joints are often expected to be perfect and according to the >> school >> book, but in the real world they are more or less imperfekt. >> Plus: >> good geomtry >> good wetting >> good surface formation >> no big dendrites >> no big voids >> good nickel barrier >> good grain structure >> >> Minus >> flux inclusions wich have not have time enough to withdraw to the >> surface. >> I think you have got a too dry paste. I've seen similar solder joints and >> we had no problems. If we had, some boards ought to show up after years >> of operation. >> >> I can't see any reason to panic, your solder joints are rather normal. Do >> this: take the polished >> crossection samples and put then in a jar with a flux remover. Place the >> jar >> in a water filled ultrasonic tank and let go for a minute. If the 'dark' >> streaks disappear, it's certainly flux. >> >> It's good for all to know how strong and longlasting solder joints can >> be >> despite numerous 'anomalies' as brother Creswick call them.I've tested >> solder joints with up to 50% voids...and they have been nearly as good as >> normal ones. Because the metallurgical properties have been good. >> >> Finally, judging solder joints from light microscope images demands a >> very >> experienced eye. If I were you , i.e. young and sweet and uncertain , I'd >> fine polish the samples, etch in a weak solution for a minute and have >> them >> placed in a SEM. Does not take many minutes to get a safer platform for >> determination. >> >> >> Inge >> >> >> >> ----- Original Message ----- >> From: "Gabriela" <[log in to unmask]> >> To: <[log in to unmask]> >> Sent: Saturday, July 04, 2009 9:54 AM >> Subject: [TN] Weird solder joints >> >> >>> Dear all, >>> By cross sectioning BGA solder joints on a failed assembly, I found that >>> the >>> suspected joints are not uniform and that they contain unusual >>> separation >>> areas. >>> >>> I suspect mixed assembly and/or bad reflow profile. >>> >>> Steve was so kind and enabled me to send the links. >>> Please may I have your opinion? >>> http://stevezeva.homestead.com/files/small.jpg >>> >>> >>> >>> <http://stevezeva.homestead.com/files/small1.jpg> >>> http://stevezeva.homestead.com/files/small1.jpg >>> >>> >>> >>> <http://stevezeva.homestead.com/files/small2.jpg> >>> http://stevezeva.homestead.com/files/small2.jpg >>> >>> http://stevezeva.homestead.com/files/small3.jpg >>> >>> <http://stevezeva.homestead.com/files/small4.jpg> >>> http://stevezeva.homestead.com/files/small4.jpg >>> >>> >>> >>> >>> Gaby >>> >>> >>> --------------------------------------------------- >>> 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 > ----------------------------------------------------- > > --------------------------------------------------------------------- > This transmission (including any attachments) may contain confidential > information, privileged material (including material protected by the > solicitor-client or other applicable privileges), or constitute non-public > information. 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