> ---------- > From: Ingemar Hernefjord > (EMW)[SMTP:[log in to unmask]] > Reply To: TechNet E-Mail Forum.;Ingemar Hernefjord (EMW) > Sent: ?יום רביעי 24 ינואר 2001? 13:55 > To: [log in to unmask] > Subject: Re: [TN] Increased Phosphorus in Electroless Ni > > Thanks Hans Shin and ya'll hou'wanna help (to use Steve's language), > I'm concentrating on reducing my list on 25 matters that can cause BGA > lift trouble. > > Did this: provoked a soldered 560BGA by installing a separating force in > one end and gradually increase the force until getting a rupture. At first > nothing happened but suddenly there was 'frrritch' and whole row began to > get apart. But several hundreds left with GRADUAL impact, last in row > didn't get any force at all. This way I had the possibility to study > exactly how the rupture occurs. Now a surprise. The classical elongated > rupture structure occurred only on the periphery of the board's solder > pad, and on some, just small strikes here and there. The rest (90%) of the > solder pads were just shiny Nickel. That RING of genuin solder is so > strong that you could hang a 200 pound Texas guy (visit at Mac Donald > included) in the 560BGA package without rupture! I can now omit bad > joints caused by a bleeding solder mask, instead the best adhesion was all > around the solder mask interface. I will be another person after this, > sigh. Double sigh. > > My intricate question: when you guys have real strong BGA solder joints, > do you know how they look like on inside? Do you have 100% adhesion all > over the solder pad? Do you at all have a requirement in your spec on > this? Don't you just rely on tempchange, ageing and other verification. > Perhaps you don't even need verifying. > > Thanks again for all support, will let you know the end...if there is such > a one. > > Ingemar > > -----Original Message----- > From: Hans Shin [mailto:[log in to unmask]] > Sent: den 23 januari 2001 17:20 > To: [log in to unmask] > Subject: Re: [TN] Increased Phosphorus in Electroless Ni > > > I thought Mark was referring to Mike Walsh's article in Circuitree > (January 2001). In either case, Mike Walsh is not "discounting the > previous work or theories," but "offer here a new and novel description of > the black pad problem and its possible elimination." And, they strongly > believe that their "work shows that the problem of black pad and many of > the other plagues of ENIG are traceable to the nickel bath." > > Ingemar, I think any of those instruments would be fine, although I don't > expect that layer to be organic, so you may want to exclude FTIR. XPS > will probably help, because it also gives you the binding energies of the > elements detected. > > Hans Shin > Pacific Testing Laboratories, Inc. > http://www.pacifictesting.com/ > > -----Original Message----- > From: Ingemar Hernefjord (EMW) [SMTP:[log in to unmask]] > Sent: Tuesday, January 23, 2001 3:51 AM > To: [log in to unmask] > Subject: Re: [TN] Increased Phosphorus in Electroless Ni > > Guys, I begin to feel schizo, > one says this and another that, and me being slow thinker, not easy. Mark > you said this: "The cause of the black pad phenomenon has been found and > fixed, > and it has nothing to do with phosphorous!" And you refer to CircuiTree's > article by George M. But he pointed that phosphorous was one of mayor > concerns, didn't he?: " Major factor Effects on black pad formation are > The Structure of Nickel deposit, The Phosphorous Content of the Nickel > deposit, The Uniformity of the Nickel and Gold Coatings and finally The > Corrosion Rate of the Immersion Gold." > > Another one, not Mark, but all of you: Lucent's people have led us back to > the central issue, the dark, thin, brittle and elusive shadow, I mean the > extremly thin layer between ordinary Ni3Sn4 and the Nickel on the lands. I > have asked a lot of people about their experience of compund findings, but > no respons yet. What tool do you recommend for examination the layer? EDS? > FTIR? XPS? SIMS? or what? Cross sectioning with polishing seems to smear > and mislead. Suppose that the BGA falls of, > -------------------------------------------------------------------------- > ------- > 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 the following message: SET > Technet NOMAIL > Search previous postings at: www.ipc.org > On-Line Resources & Databases > > E-mail 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 > -------------------------------------------------------------------------- > ------- > > -------------------------------------------------------------------------- > ------- > 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 the following message: SET > Technet NOMAIL > Search previous postings at: www.ipc.org > On-Line Resources & Databases > > E-mail 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 > -------------------------------------------------------------------------- > ------- >