agree. no fun at all ;-) http://extra.ivf.se/eqs/dokument/7%20pet6005.pdf > Joyce, I hate to spoil your fun, but even that Neanderthal Rework Process > will not overly extend the IMF by more than 1 or 2 microns. > When the original IMF is formed during reflow, any additional rework is > simply soldering solder to the solder already present. The IMF does not > increase in thickness appreciably. > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Joyce Koo > Sent: Thursday, September 17, 2015 8:00 AM > To: [log in to unmask] > Subject: Re: [TN] BGA Reworked Intermetallic > > Hot plate and soaking the part intend to repair in flux and walk away > until it was reflowed. remove the defective part and let the PWA cool > down. put back on the hot plate, with additional flux and clean the site, > remove access old solder. add additional solder to address the pad. Cool > down again by remove from the hot plate. position the part using > microscope that is not near the work station with tacker flux, bring back > to the hot plate and reflow again, using tooling to perform minor > adjustment to position the part and final cool down... if you check for > the IMC after such a repair, you get very thick IMC - the overall time > above TL is 5 to 6 x compare to your SMT the least.... (I was told it is > not un-common in some places for "repair"). scary. > jk >> But Vlad - those conditions are so extreme that something is clearly >> incorrect in the process so focusing on the IMC is the wrong root >> cause analysis path. The focus should be on how/why such an extreme >> amount of IMC is being created in the first place. >> >> Dave >> >> On Thu, Sep 17, 2015 at 7:36 AM, <[log in to unmask]> wrote: >> >>> Hi Dave, >>> >>> That what exactly my point. It does happen under certain conditions, >>> so I always advise our customers not to start with a very thick layer >>> of intermetallics. >>> >>> Cheers, >>> >>> Vladimir >>> >>> Sent from my BlackBerry 10 smartphone on the Rogers network. >>> *From: *David Hillman >>> *Sent: *Thursday, September 17, 2015 08:22 >>> *To: *Vladimir Igoshev >>> *Cc: *TechNet E-Mail Forum >>> *Subject: *Re: [TN] BGA Reworked Intermetallic >>> >>> Hi Vlad - the growth rates of IMCs are pretty well known as they >>> follow an Arrhenius equation behavior. The growth of IMCs from 25C >>> -100C is extremely low so unless you have a product service >>> environment that has a high temperature such as 150C for long time >>> periods, you just are not going to "grow" enough IMC thickness to >>> impact solder joint integrity. Having an IMC of 12 microns (400 >>> uinches) is HUGE and clearly not a normal, typical case found in >>> standard electronics production. The biggest issue with having an IMC >>> discussion is that the data doesn't support IMC failure as a typical >>> root cause for solder joints when we start crunching the numbers. I >>> working with one of our industry colleagues and we are pulling >>> together a paper on industry "myths" where we plan on including the >>> topic of IMCs. >>> As >>> you can imagine, its a fun paper to work on and we hope to have it >>> publish in the upcoming year(ish). >>> >>> Dave >>> >>> On Wed, Sep 16, 2015 at 9:52 PM, <[log in to unmask]> wrote: >>> >>>> Hi Dave, >>>> >>>> As far as I remember I said it's a reverie for disaster. As you know >>>> intermetallics will grow over time and a starting point of 10 or so >>>> microns doesn't help. >>>> >>>> I had several cases of failure (cracked intermetallics) after it >>>> grew up to 12-15 microns. >>>> >>>> Does it happen all the time? I don't know May be not, but the cases >>>> I had are good enough "argument" , at least for me. >>>> >>>> Regards, >>>> >>>> Vladimir >>>> >>>> Sent from my BlackBerry 10 smartphone on the Rogers network. >>>> *From: *David Hillman >>>> *Sent: *Wednesday, September 16, 2015 22:44 >>>> *To: *TechNet E-Mail Forum; Vladimir Igoshev >>>> *Subject: *Re: [TN] BGA Reworked Intermetallic >>>> >>>> Hi Vlad - what data do you have that 10 micron thick layer of IMC >>>> results in the failure of the BGA? There is TONS of subjective >>>> comments in the published literature but no hard data of failures. >>>> As a basic materials engineering principle, IMCs are brittle but >>>> that specific material characteristic seems to be the only reason >>>> folks make statements that a "thick" IMC is bad. Should we work to >>>> keep IMC layers minimized? >>>> Absolutely >>>> but I don't believe, as technologists, we should keep propagating >>>> the myth about thick IMC layers without having published, reviewable >>>> data. >>>> >>>> Dave Hillman >>>> Rockwell Collins >>>> [log in to unmask] >>>> >>>> On Wed, Sep 16, 2015 at 9:38 AM, Vladimir Igoshev < >>>> [log in to unmask]> wrote: >>>> >>>>> 10 microns thick layer is a perfect way for a disaster down the >>>>> road :-). >>>>> >>>>> There are no parameters for E-Ni, but the appearance of the >>>>> interface and a P-enriched layer ‎is important. >>>>> >>>>> Vladimir >>>>> >>>>> Sent from my BlackBerry 10 smartphone on the Rogers network. >>>>> Original Message >>>>> From: Victor Hernandez >>>>> Sent: Wednesday, September 16, 2015 10:11 >>>>> To: [log in to unmask] >>>>> Reply To: TechNet E-Mail Forum >>>>> Subject: Re: [TN] BGA Reworked Intermetallic >>>>> >>>>> On ENIG surface I don't see much of an increase in the IMC >>>>> formation thickness. However, on Cu it is a different story. I have >>>>> measured IMC formation greater tham 10 microns. Not sure of the >>>>> below statement about E-NI parameter. Please explain!!! >>>>> >>>>> Victor, >>>>> >>>>> -----Original Message----- >>>>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Vladimir >>>>> Igoshev >>>>> Sent: Wednesday, September 16, 2015 8:12 AM >>>>> To: [log in to unmask] >>>>> Subject: Re: [TN] BGA Reworked Intermetallic >>>>> >>>>> The "magic" Number should stay the same 1-3 micron but you'd also >>>>> have to keep an eye on what happened to the layer of E-Ni underneath. >>>>> >>>>> Regards, >>>>> >>>>> Vladimir >>>>> >>>>> SENTEC >>>>> >>>>> Sent from my BlackBerry 10 smartphone on the Rogers network. >>>>> Original Message >>>>> From: Datacom - Juliano Ribeiro >>>>> Sent: Wednesday, September 16, 2015 09:09 >>>>> To: [log in to unmask] >>>>> Reply To: TechNet E-Mail Forum >>>>> Subject: [TN] BGA Reworked Intermetallic >>>>> >>>>> Hi to all, >>>>> >>>>> >>>>> >>>>> When we reworked the BGA, removed the component of the board and >>>>> replacement another BGA, what's the intermetallic thickness ideal >>>>> after the rework? >>>>> >>>>> >>>>> >>>>> p.s: Our pcb is ENIG finished and the solder is Tin Lead. >>>>> >>>>> >>>>> >>>>> _____________________________ >>>>> >>>>> Juliano Bettim Ribeiro >>>>> >>>>> DATACOM >>>>> >>>>> ENGENHARIA DE PROCESSOS >>>>> Rua América Nº 1000 - Eldorado do Sul - RS CEP: 92990-000 >>>>> +55 (51) 8446-2135 >>>>> >>>>> +55 (51) 3933-3000 >>>>> >>>>> Ramal: 3484 >>>>> [log in to unmask] www.datacom.ind.br >>>>> >>>>> >>>>> >>>>> >>>>> ___________________________________________________________________ >>>>> ___ This email has been scanned by the Symantec Email >>>>> Security.cloud service. >>>>> For more information please contact helpdesk at x2960 or >>>>> [log in to unmask] >>>>> ___________________________________________________________________ >>>>> ___ >>>>> >>>>> ___________________________________________________________________ >>>>> ___ This email has been scanned by the Symantec Email >>>>> Security.cloud service. >>>>> For more information please contact helpdesk at x2960 or >>>>> [log in to unmask] >>>>> ___________________________________________________________________ >>>>> ___ >>>>> >>>>> ___________________________________________________________________ >>>>> ___ This email has been scanned by the Symantec Email >>>>> Security.cloud service. >>>>> For more information please contact helpdesk at x2960 or >>>>> [log in to unmask] >>>>> ___________________________________________________________________ >>>>> ___ >>>>> >>>>> ___________________________________________________________________ >>>>> ___ This email has been scanned by the Symantec Email >>>>> Security.cloud service. >>>>> For more information please contact helpdesk at x2960 or >>>>> [log in to unmask] >>>>> ___________________________________________________________________ >>>>> ___ >>>>> >>>> >>>> >>>> >>> >>> >> >> ______________________________________________________________________ >> This email has been scanned by the Symantec Email Security.cloud >> service. >> For more information please contact helpdesk at x2960 or >> [log in to unmask] >> ______________________________________________________________________ >> > > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > For more information please contact helpdesk at x2960 or [log in to unmask] > ______________________________________________________________________ > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > For more information please contact helpdesk at x2960 or [log in to unmask] > ______________________________________________________________________ > ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. 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