Dave,
in your neck of the woods, the thick IMC might be produced by
"significantly messed up" process.  However, in the other wild west and
east, when some of the repair are done by high power hair dryer and
manually done few times plus aggressively fluxing, thick IMC might be a
significantly concern.... (the old day maximum allowable repair is 2X per
board with specific repair method, but I don't think that apply to
nowadays... at least I haven't see the design dictate the maximum repair
clause in the hand off documents or MFG readiness review for more than 10
years... contract MFG killed that part of checks and balance).
my 2 cents.
              jk
> Hi folks - I don't have the data (yet, work is in progress) but you would
> have to need to have a significantly messed up process to produce an IMC
> thick enough to result in a solder joint failure in a electronics product.
> I think the "thick IMC" concern is more a myth than a typical industry
> failure mode on printed circuit assemblies.
>
> Dave
>
> On Wed, Sep 16, 2015 at 10:47 AM, Stadem, Richard D. <
> [log in to unmask]> wrote:
>
>> No, that is not possible. The variations in the worldwide electronics
>> soldering industry go far beyond what most of us see with typical ENIG,
>> IAg, IAuCu (flash gold on copper), HASL, Pb-free HASL, OSP, and ten
>> thousand billion different variations of component lead basis metals
>> involved. How could anyone possibly characterize all of the different
>> combinations and put an appropriate IMF thickness for each one? The
>> charted
>> document would be bigger than great-gramma's Bible.
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
>> Sent: Wednesday, September 16, 2015 9:51 AM
>> To: [log in to unmask]
>> Subject: Re: [TN] BGA Reworked Intermetallic
>>
>> Does IPC STD provide a guideline for IMC formation thickness, ENIG or
>> Cu,
>> after 1x, 2x, 3x, 4x, 5x and 6x Forced RW?   IMC formation thickness
>> varies
>> by type of solder, SnPb and LF Solder.   Let’s keep the discussion
>> going!!!
>>
>> Victor,
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Vladimir Igoshev
>> Sent: Wednesday, September 16, 2015 9:38 AM
>> To: [log in to unmask]
>> Subject: Re: [TN] BGA Reworked Intermetallic
>>
>> 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 than 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
>>
>>
>>
>>
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